Merge storytold/main into feat/model3d-render

# Conflicts:
#	crates/automation/src/lib.rs
#	crates/automation/tests/it/main.rs

CLAUDE.md

@@ -23,7 +23,7 @@ PdfCraft is a clean-room, open-source, Rust-native PDF application targeting Ado
 - **Layering.** Nothing below L7 depends on egui/winit/eframe/rfd (`plan/architecture.md` §3). `cos`/`filters`/`crypt`/`arlington` stay standalone.
 - **Page input.** Page modules read `PagePointer` (`crates/ui-egui/src/page_pointer.rs`), never egui's raw pointer state (`hover_pos`, `interact_pos`, `latest_pos`, `press_origin`, button reads); `page_pointer::tests::page_modules_read_the_pointer_only_through_page_pointer` enforces it.
 - **Page cursor.** Page modules claim the cursor for what is under the pointer (`view.cursor.claim(Layer::…, icon)`, `crates/ui-egui/src/canvas/page_cursor.rs`), never set it (`set_cursor_icon`, `cursor_icon =`, `on_hover_cursor`); `document_area` sets it once, from the claim on the highest layer the active tool reaches. `page_pointer::tests::page_modules_claim_the_cursor_and_never_set_it` enforces it.
-- **Page presses.** A page module decides what of its own is under a point in one hit test, which returns a `Hit` (owner, layer, cursor, tip; `crates/ui-egui/src/canvas/page_router.rs`) and gives its cursor, its tip and its press. It acts on a press only when the router says the press is its own (`view.router.owner(page)`), never by testing the press point again or by asking another module whether it wants it. Escape cancels any press the pages hold (`cancel_on_escape`), and that press is ignored until the button is up. `page_modules_take_presses_from_the_router_without_repeating_hit_tests` guards the centralized hit calls and captured-owner handlers; runtime routing tests cover gesture behavior.
+- **Page presses.** A page module decides what of its own is under a point in one hit test, which returns a `Hit` (owner, layer, cursor, tip; `crates/ui-egui/src/canvas/page_router.rs`) and gives its cursor, its tip and its press. It acts on a press only when the press is its own or, for the active tool, nobody's: the page view tells it which (`PagePress`: its own, nobody's, or another page's), and it never tests the press point again or asks another module whether it wants it. Escape cancels any press the pages hold (`cancel_on_escape`), and that press is ignored until the button is up. `page_pointer::tests::page_modules_act_on_a_press_only_through_the_router` enforces it.
 - **Fidelity.** The PDF object graph is the model. Preserve unknown data. Saves are incremental unless a full rewrite is required. Never silently drop or repair data without recording it.
 - **Never panic.** Every PDF, script, MCP call, settings file and keystroke is untrusted input, and none of it may crash the app or lose the user's work. This outranks feature work. Return `Result` (the crate's error enum) and propagate with `?`, or fall back leniently and record it. In non-test code:
   - No `unwrap`/`expect`/`panic!`/`unreachable!`/`todo!` unless it is provably infallible, with a comment saying why.

ROADMAP.md

@@ -223,12 +223,16 @@ Ranked; detail and the full milestone table in [docs/roadmap.md](docs/roadmap.md
 
 ## Progress log
 
+- **2026-11-03 (M11, shared JBIG2 dictionary):** With Monochrome Images set to JBIG2, Optimize has up to 16 JBIG2 images share one symbol dictionary (`/JBIG2Globals`), the letters found on more than one page stored once, when that is smaller (`pdfcraft_filters::encode_jbig2_shared`). Eight pages of 10 pt text rendered at 300 dpi take 41% less in Helvetica and 42% in Times than coded alone, 10% in Courier; groups of 16 save 45%, of 32 only 47%. Only images redaction can store again without the dictionary share one (image masks and DeviceGray named directly, at most 64 Mi pixels), and redacting one stores the rest of its group so, which the group bounds to 15.
+
 - **2026-11-03 (M5, #5850 review):** Resolve indirect IT when recognizing typewriter contents and Fill & Sign marks. Comment listing and property lookup retain their existing direct-Subtype behavior. A real double-click Edit composer preserves the typewriter’s text as written; ordinary comment edits keep trimming. Regressions cover direct Subtype with indirect intent, save/reopen, raw posted contents and same-index comments on different pages. The existing live-movement test now commits its setup with an outside click rather than Enter. Estimates unchanged.
 
 - **2026-11-03 (M5, #5850):** Fill & Sign Enter inserts a line break in a growing editor; clicking outside commits and Escape cancels. Nonempty text keeps leading, internal and trailing line breaks. The headless fill_sign_add path sizes its typewriter box for the same wrapped lines so saved appearances show every row. Production-order keyboard and engine save/reopen/render regressions exercise the UI and headless callers. Estimates unchanged.
 
 - **2026-11-03 (M7, #5835):** In image crop mode, a right-click on the image, its crop box or its handles keeps the crop and opens no menu, so the menu no longer switches as the pointer moves. A right-click elsewhere clears the selection and opens the page menu. UI tests cover all four page rotations, overlapping images, a 45° image, and a check that the Done/Cancel/Remove Crop pills at a page edge still keep the crop.
 
+- **2026-11-02 (M12, #1297):** `model_add` embeds a U3D or PRC file, recognised by its header, as a 3D annotation with a chosen activation and a poster (an image or PDF page fitted in the box, or a labelled frame); an older file's catalog `/Version` is raised to what the model needs. Views, a rendered poster and a UI command are later steps. Estimates unchanged.
+
 - **2026-11-02 (M10, #5743):** macOS print jobs name their title and owner (`com.apple.print.JobInfo.PMJobName`, `PMJobOwner`), as the system print dialog does, because a Kyocera filter crashes on a job without them. Checked by a test and through `doc_print` against a stand-in `lp`; not yet on a physical printer.
 
 - **2026-11-01 (M7, #5657):** Header/footer, watermark and background additions and replacements stage the complete call before committing. Synthetic later-page failures preserve exact incremental bytes, object count, dirty state and allocation cursor; success controls retain other marks and shared/inherited resources. Estimates unchanged.

crates/annot/src/appearance.rs

@@ -278,7 +278,7 @@ fn ext_gstate(opacity: f64, multiply: bool) -> Option<Dict> {
     Some(res)
 }
 
-fn form(bbox: [f64; 4], content: &[u8], resources: Dict) -> Stream {
+pub(crate) fn form(bbox: [f64; 4], content: &[u8], resources: Dict) -> Stream {
     let mut d = Dict::new();
     d.set(b"Type".to_vec(), Object::name("XObject"));
     d.set(b"Subtype".to_vec(), Object::name("Form"));
@@ -288,6 +288,18 @@ fn form(bbox: [f64; 4], content: &[u8], resources: Dict) -> Stream {
     Stream::flate(d, content)
 }
 
+/// The `cm` that draws a picture into `at`: an image (its unit square) or a form XObject whose
+/// `/Matrix` maps it to `size` points (`None`, or a side that is not positive, draws nothing).
+pub(crate) fn picture_place(at: [f64; 4], image: bool, size: Option<(f64, f64)>) -> Option<String> {
+    let [x0, y0, x1, y1] = at;
+    let (w, h) = (x1 - x0, y1 - y0);
+    if image {
+        return Some(format!("{} 0 0 {} {} {} cm", n(w), n(h), n(x0), n(y0)));
+    }
+    let (sw, sh) = size.filter(|(sw, sh)| *sw > 0.0 && *sh > 0.0)?;
+    Some(format!("{} 0 0 {} {} {} cm", n(w / sw), n(h / sh), n(x0), n(y0)))
+}
+
 /// The page `/Rotate` an image signature's picture is turned back by (`/PCPictureRotate`, written
 /// when the signature is added to a turned page): 0, 90, 180 or 270.
 pub(crate) fn picture_turn(d: &Dict) -> i64 {
@@ -325,7 +337,7 @@ pub fn undrawable_text(d: &Dict) -> Option<(&'static str, char)> {
 }
 
 /// `/Font` resources naming `/Helv`: standard Helvetica with WinAnsiEncoding.
-fn helvetica_resource() -> Object {
+pub(crate) fn helvetica_resource() -> Object {
     let mut font = Dict::new();
     font.set(b"Type".to_vec(), Object::name("Font"));
     font.set(b"Subtype".to_vec(), Object::name("Type1"));
@@ -786,15 +798,12 @@ fn draw_stamp(context: &AppearanceContext<'_>, mut drawing: AppearanceDrawing) -
     // the standard counter-rotation as its form `/Matrix`: viewers fit the turned
     // bounding box to `/Rect` (ISO 32000-2 §12.5.5), so it reads upright as displayed.
     if let Some(pic) = d.get(b"PCPicture").and_then(Object::as_ref) {
-        let [x0, y0, x1, y1] = rect;
-        let (w, h) = (x1 - x0, y1 - y0);
         let image = matches!(d.get(b"PCPictureImage"), Some(Object::Bool(true)));
-        let place = if image {
-            format!("{} 0 0 {} {} {} cm", n(w), n(h), n(x0), n(y0))
-        } else {
-            let size = nums(d, b"PCPictureSize").filter(|s| s.len() == 2 && s[0] > 0.0 && s[1] > 0.0)?;
-            format!("{} 0 0 {} {} {} cm", n(w / size[0]), n(h / size[1]), n(x0), n(y0))
-        };
+        let size = nums(d, b"PCPictureSize").and_then(|s| match s.as_slice() {
+            [w, h] if *w > 0.0 && *h > 0.0 => Some((*w, *h)),
+            _ => None,
+        });
+        let place = picture_place(rect, image, size)?;
         c.push_str(&format!("q {place} /Pic Do Q\n"));
         let mut xo = Dict::new();
         xo.set(b"Pic".to_vec(), Object::Ref(pic));

crates/annot/src/lib.rs

@@ -24,6 +24,7 @@ mod info;
 mod lookup;
 mod model3d;
 mod modify;
+mod threed;
 mod types;
 
 #[cfg(test)]
@@ -43,6 +44,7 @@ pub use modify::{
     add_reply, add_text_replacement, deletable, delete_annotation, erase_ink, fillable, goes_with, lift_annotation, move_annotation, set_contents,
     set_fill, set_font_size, set_locked, set_marked, set_points, set_rect, set_review_state, set_style, with_replies_and_popups,
 };
+pub use threed::{Activation as Activation3d, MAX_MODEL_BYTES, ModelFormat, NewModel3d, PosterPicture, add_3d_model, check_model};
 pub use types::{
     AttachIcon, FillMark, LineEnding, Markup, Meta, NOTE_SIZE, NewAnnotation, NoteIcon, OverlayFont, OverlayLook, ReviewState, Rgb, Shape,
     StampGroup, StampKind, Style, StyleChange, TextReplacement, rect_quad,
@@ -72,6 +74,12 @@ pub enum AnnotError {
     /// with a font that has those characters. The message names the character.
     #[error("{0}")]
     Undrawable(String),
+    /// A 3D model file that is neither U3D (starts with `U3D` and a zero byte) nor PRC (starts `PRC`).
+    #[error("not a 3D model: the file must be U3D (ECMA-363) or PRC (ISO 14739-1)")]
+    NotAModel,
+    /// A 3D model larger than `MAX_MODEL_BYTES`.
+    #[error("the 3D model is {size} bytes; the largest accepted is {max}")]
+    ModelTooLarge { size: usize, max: usize },
     #[error("{0}")]
     Cos(#[from] pdfcraft_cos::CosError),
 }

crates/annot/src/tests.rs

@@ -2251,6 +2251,141 @@ fn freehand_highlight_is_compatible_ink_with_marker_blending() {
     }
 }
 
+/// A 3D annotation is PDF 1.6 and a PRC model 1.7 (ISO 32000-2 §13.6): an older document's
+/// catalog says so, and a newer one is left as it is.
+#[test]
+fn a_3d_model_raises_an_older_document_to_its_version() {
+    let catalog_version = |doc: &Document| {
+        let root = doc.root().unwrap();
+        doc.get(root).as_dict().unwrap().name(b"Version").map(<[u8]>::to_vec)
+    };
+    let add = |doc: &mut Document, model: &[u8]| {
+        let new = NewModel3d { page: 0, rect: [100.0, 100.0, 300.0, 300.0], model, activation: Activation3d::default(), poster: None, contents: "" };
+        add_3d_model(doc, &new, &meta("m")).unwrap();
+    };
+    let mut doc = fixture();
+    add(&mut doc, b"U3D\0rest");
+    assert_eq!(catalog_version(&reopen(&doc)), None, "a 1.7 file needs nothing for U3D");
+    for (model, version) in [(&b"U3D\0rest"[..], &b"1.6"[..]), (b"PRC rest", b"1.7")] {
+        let mut doc = fixture();
+        doc.set_version("1.4");
+        add(&mut doc, model);
+        assert_eq!(catalog_version(&reopen(&doc)).as_deref(), Some(version));
+    }
+    let mut doc = fixture();
+    doc.set_version("2.0");
+    add(&mut doc, b"PRC rest");
+    assert_eq!(catalog_version(&reopen(&doc)), None, "a 2.0 file takes PRC as it is");
+}
+
+/// Before 2.0, PRC is an Adobe extension to PDF 1.7 (§7.12): a PRC model declares it, keeping
+/// other extensions and a later ADBE level; U3D and a 2.0 file need nothing.
+#[test]
+fn a_prc_model_declares_the_adobe_extension_before_pdf_2() {
+    let adbe = |doc: &Document| {
+        let root = doc.root().unwrap();
+        let ext = doc.get(root).as_dict().unwrap().get(b"Extensions").map(|e| doc.resolve(e).as_dict().unwrap().clone());
+        ext.map(|e| {
+            let adbe = e.get(b"ADBE").map(|a| a.as_dict().unwrap().clone());
+            (e.get(b"XYZ").is_some(), adbe.map(|a| (a.name(b"BaseVersion").map(<[u8]>::to_vec), a.get(b"ExtensionLevel").and_then(Object::as_int))))
+        })
+    };
+    let add = |doc: &mut Document, model: &[u8]| {
+        let new = NewModel3d { page: 0, rect: [100.0, 100.0, 300.0, 300.0], model, activation: Activation3d::default(), poster: None, contents: "" };
+        add_3d_model(doc, &new, &meta("m")).unwrap();
+    };
+    let mut doc = fixture();
+    add(&mut doc, b"PRC rest");
+    assert_eq!(adbe(&reopen(&doc)), Some((false, Some((Some(b"1.7".to_vec()), Some(1))))));
+    let mut doc = fixture();
+    add(&mut doc, b"U3Drest");
+    assert_eq!(adbe(&reopen(&doc)), None, "U3D is in ISO 32000-1");
+    let mut doc = fixture();
+    doc.set_version("2.0");
+    add(&mut doc, b"PRC rest");
+    assert_eq!(adbe(&reopen(&doc)), None, "PRC is in ISO 32000-2");
+
+    let mut doc = fixture();
+    let root = doc.root().unwrap();
+    let mut level3 = Dict::new();
+    level3.set(b"BaseVersion".to_vec(), Object::name("1.7"));
+    level3.set(b"ExtensionLevel".to_vec(), Object::Int(3));
+    let mut ext = Dict::new();
+    ext.set(b"ADBE".to_vec(), Object::Dict(level3));
+    ext.set(b"XYZ".to_vec(), Object::Dict(Dict::new()));
+    doc.update_dict(root, |c| c.set(b"Extensions".to_vec(), Object::Dict(ext.clone()))).unwrap();
+    add(&mut doc, b"PRC rest");
+    assert_eq!(adbe(&reopen(&doc)), Some((true, Some((Some(b"1.7".to_vec()), Some(3))))), "a later level is kept");
+    ext.remove(b"ADBE");
+    let mut doc = fixture();
+    doc.update_dict(root, |c| c.set(b"Extensions".to_vec(), Object::Dict(ext))).unwrap();
+    add(&mut doc, b"PRC rest");
+    assert_eq!(adbe(&reopen(&doc)), Some((true, Some((Some(b"1.7".to_vec()), Some(1))))), "other extensions are kept");
+
+    let mut doc = fixture();
+    let mut ext = Dict::new();
+    ext.set(b"ADBE".to_vec(), Object::Array(vec![Object::Dict(Dict::new())]));
+    let ext = doc.add(Object::Dict(ext));
+    doc.update_dict(root, |c| c.set(b"Extensions".to_vec(), Object::Ref(ext))).unwrap();
+    add(&mut doc, b"PRC rest");
+    let doc = reopen(&doc);
+    let ext = doc.resolve(doc.get(doc.root().unwrap()).as_dict().unwrap().get(b"Extensions").unwrap());
+    assert!(ext.as_dict().unwrap().get(b"ADBE").unwrap().as_array().is_some(), "an array of ADBE extensions is left alone");
+}
+
+#[test]
+fn a_picture_is_placed_by_its_box_and_a_form_needs_a_positive_size() {
+    let at = [10.0, 20.0, 110.0, 70.0];
+    assert_eq!(appearance::picture_place(at, true, None).as_deref(), Some("100 0 0 50 10 20 cm"), "an image fills its unit square");
+    assert_eq!(appearance::picture_place(at, false, Some((200.0, 25.0))).as_deref(), Some("0.5 0 0 2 10 20 cm"));
+    for size in [None, Some((0.0, 25.0)), Some((200.0, -1.0))] {
+        assert_eq!(appearance::picture_place(at, false, size), None, "{size:?}");
+    }
+}
+
+/// The poster's box must lie in the rectangle, and a form poster needs a size to scale by.
+#[test]
+fn a_3d_poster_outside_its_rectangle_or_without_a_size_is_refused() {
+    let picture = |at: [f64; 4], size: (f64, f64)| PosterPicture { xobject: ObjRef { num: 6, generation: 0 }, image: false, size, at };
+    for (poster, why) in [
+        (picture([50.0, 100.0, 250.0, 300.0], (10.0, 10.0)), "starts left of the rectangle"),
+        (picture([100.0, 100.0, 300.0, 301.0], (10.0, 10.0)), "ends above it"),
+        (picture([100.0, 100.0, 300.0, 300.0], (0.0, 10.0)), "has no width"),
+        (picture([100.0 - 2e-7, 150.0, 100.0 - 1e-7, 200.0], (10.0, 10.0)), "lies outside within the rounding slack"),
+    ] {
+        let mut doc = fixture();
+        let new = NewModel3d {
+            page: 0,
+            rect: [100.0, 100.0, 300.0, 300.0],
+            model: b"PRC rest",
+            activation: Activation3d::default(),
+            poster: Some(poster),
+            contents: "",
+        };
+        assert!(matches!(add_3d_model(&mut doc, &new, &meta("m")), Err(AnnotError::Invalid(_))), "{why}");
+        assert_eq!(list(&doc, 0).len(), 1, "{why}: nothing added");
+    }
+}
+
+/// A poster box fitted to the rectangle in floating point ends an ulp outside it: a 7×3 picture
+/// centred in [0 100 3.6 110.8] spans -2.2e-16 to 3.6000000000000005. It is taken, inside the
+/// rectangle.
+#[test]
+fn a_3d_poster_fitted_to_its_rectangle_with_rounding_is_taken() {
+    let mut doc = fixture();
+    let at = [-2.220446049250313e-16, 104.62857142857143, 3.6000000000000005, 106.17142857142858];
+    let poster = PosterPicture { xobject: ObjRef { num: 6, generation: 0 }, image: false, size: (7.0, 3.0), at };
+    let new = NewModel3d {
+        page: 0,
+        rect: [0.0, 100.0, 3.6, 110.8],
+        model: b"PRC rest",
+        activation: Activation3d::default(),
+        poster: Some(poster),
+        contents: "",
+    };
+    assert_eq!(add_3d_model(&mut doc, &new, &meta("m")), Ok(1));
+}
+
 #[test]
 fn indirect_typewriter_names_keep_outer_whitespace_in_summaries() {
     let mut doc = fixture();

crates/annot/src/threed.rs

@@ -0,0 +1,292 @@
+//! 3D annotations (ISO 32000-2 §13.6.2): a U3D or PRC model shown in a rectangle on a page,
+//! with a poster (`/AP /N`) for printing, for readers without 3D, and until it is activated.
+
+use super::create::{finite, normalize, num_array};
+use super::lookup::{annots, page_ref, set_annots};
+use super::types::{FLAG_PRINT, Meta};
+use super::{AnnotError, Dict, Document, ObjRef, Object, PdfString, Stream, appearance, n};
+
+/// The largest model accepted, in bytes: well past real U3D/PRC files, and bounded because the
+/// model is held and compressed in memory.
+pub const MAX_MODEL_BYTES: usize = 256 << 20;
+
+/// What the poster says when there is no picture.
+const PLACEHOLDER_LABEL: &str = "3D model";
+
+/// A 3D stream's data format (§13.6.3): ECMA-363 U3D or ISO 14739-1 PRC.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum ModelFormat {
+    U3d,
+    Prc,
+}
+
+impl ModelFormat {
+    /// The format a model file's first bytes declare: U3D files start `U3D\0` (ECMA-363 file
+    /// header block type), PRC files start `PRC`.
+    ///
+    /// # Errors
+    ///
+    /// [`AnnotError::NotAModel`] for anything else.
+    pub fn detect(bytes: &[u8]) -> Result<Self, AnnotError> {
+        if bytes.starts_with(b"U3D\0") {
+            Ok(Self::U3d)
+        } else if bytes.starts_with(b"PRC") {
+            Ok(Self::Prc)
+        } else {
+            Err(AnnotError::NotAModel)
+        }
+    }
+
+    /// The 3D stream's `/Subtype`.
+    pub fn subtype(self) -> &'static str {
+        match self {
+            Self::U3d => "U3D",
+            Self::Prc => "PRC",
+        }
+    }
+
+    /// The PDF version a document holding it needs (§13.6): a 3D annotation is 1.6, a PRC stream
+    /// 1.7 under Adobe's extension, declared by [`add_3d_model`] (PDF 2.0 takes PRC as standard).
+    pub fn version(self) -> &'static str {
+        match self {
+            Self::U3d => "1.6",
+            Self::Prc => "1.7",
+        }
+    }
+}
+
+/// When a reader turns the poster into the live model (§13.6.2, the activation dictionary's
+/// `/A`). The standard's default is [`Self::Click`].
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum Activation {
+    /// `/XA`: when the user clicks it; it prints as its poster.
+    #[default]
+    Click,
+    /// `/PO`: when the page opens.
+    PageOpen,
+    /// `/PV`: when the page becomes visible.
+    PageVisible,
+}
+
+impl Activation {
+    /// Every activation, with the word a tool argument names it by.
+    pub const ALL: [(Self, &'static str); 3] = [(Self::Click, "click"), (Self::PageOpen, "page_open"), (Self::PageVisible, "page_visible")];
+
+    /// The `/A` name.
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Click => "XA",
+            Self::PageOpen => "PO",
+            Self::PageVisible => "PV",
+        }
+    }
+}
+
+/// A picture already in the document (an image XObject, or a form XObject whose `/Matrix` maps it
+/// to `size` points) drawn into `at`, a box inside the annotation's rectangle.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct PosterPicture {
+    pub xobject: ObjRef,
+    pub image: bool,
+    pub size: (f64, f64),
+    pub at: [f64; 4],
+}
+
+/// A 3D model to add on `page` (0-based) in `rect` (user space).
+#[derive(Clone, Debug, PartialEq)]
+pub struct NewModel3d<'a> {
+    pub page: usize,
+    pub rect: [f64; 4],
+    pub model: &'a [u8],
+    pub activation: Activation,
+    /// The poster's picture; `None` draws a labelled frame.
+    pub poster: Option<PosterPicture>,
+    /// `/Contents`: the annotation's alternate description (§12.5.2).
+    pub contents: &'a str,
+}
+
+/// Check a model before anything is added: its size and its format.
+///
+/// # Errors
+///
+/// [`AnnotError::ModelTooLarge`] past [`MAX_MODEL_BYTES`], else as [`ModelFormat::detect`].
+pub fn check_model(model: &[u8]) -> Result<ModelFormat, AnnotError> {
+    check_model_size(model, MAX_MODEL_BYTES)?;
+    ModelFormat::detect(model)
+}
+
+fn check_model_size(model: &[u8], max: usize) -> Result<(), AnnotError> {
+    if model.len() > max {
+        return Err(AnnotError::ModelTooLarge { size: model.len(), max });
+    }
+    Ok(())
+}
+
+/// Add a 3D annotation: the model in a Flate-compressed 3D stream referenced from `/3DD` (so the
+/// annotation has its own instance, §13.6.2), `/3DA` stating only `/A`, and the poster as `/AP /N`.
+/// No view (`/3DV`, `/VA`) is written: readers open on the model's own default view. A document
+/// older than [`ModelFormat::version`] is raised to it. Returns its index in the page's `/Annots`.
+///
+/// # Errors
+///
+/// As [`check_model`]; [`AnnotError::NoSuchPage`]; [`AnnotError::Invalid`] for a rectangle with no
+/// area or a poster box outside it.
+pub fn add_3d_model(doc: &mut Document, new: &NewModel3d<'_>, meta: &Meta) -> Result<usize, AnnotError> {
+    let format = check_model(new.model)?;
+    let page = page_ref(doc, new.page)?;
+    let rect = normalize(new.rect);
+    if !finite(&new.rect) || rect[2] - rect[0] < 1.0 || rect[3] - rect[1] < 1.0 {
+        return Err(AnnotError::Invalid("invalid rectangle for the 3D model (each side at least 1 pt)".into()));
+    }
+    let poster = match &new.poster {
+        Some(p) => picture_poster(rect, p)?,
+        None => placeholder_poster(rect),
+    };
+    let mut stream = Dict::new();
+    stream.set(b"Type".to_vec(), Object::name("3D"));
+    stream.set(b"Subtype".to_vec(), Object::name(format.subtype()));
+    let stream = doc.add(Object::Stream(Stream::flate(stream, new.model)));
+    let poster = doc.add(Object::Stream(poster));
+    let d = annotation_dict(new, rect, page, stream, poster, meta);
+    let r = doc.add(Object::Dict(d));
+    let mut list = annots(doc, page);
+    let index = list.len();
+    list.push(Object::Ref(r));
+    set_annots(doc, page, list)?;
+    at_least_version(doc, format.version())?;
+    if format == ModelFormat::Prc && !at_least(doc, "2.0") {
+        declare_prc_extension(doc)?;
+    }
+    Ok(index)
+}
+
+/// Whether the header or the catalog `/Version` says `min` or later (§7.7.2).
+fn at_least(doc: &Document, min: &str) -> bool {
+    let reached = |v: &[u8]| v.len() >= 3 && v >= min.as_bytes();
+    let catalog = doc.root().and_then(|root| doc.get(root).as_dict().and_then(|c| c.get(b"Version").cloned()));
+    let catalog = catalog.and_then(|v| doc.resolve(&v).as_name().map(<[u8]>::to_vec));
+    reached(doc.version().as_bytes()) || catalog.as_deref().is_some_and(reached)
+}
+
+/// PRC came before PDF 2.0 as an Adobe extension to 1.7: such a file declares
+/// `/Extensions /ADBE` with ExtensionLevel 1 or later (§7.12). Other extensions and an ADBE entry
+/// that already has a level are kept; one that is not a dictionary (an array of them) is left alone.
+fn declare_prc_extension(doc: &mut Document) -> Result<(), AnnotError> {
+    let Some(root) = doc.root() else { return Ok(()) };
+    let catalog = doc.get(root);
+    // `None` when present but not a dictionary; an empty one when absent.
+    let dict_or_new = |o: Option<&Object>| match o.map(|o| doc.resolve(o)) {
+        None => Some(Dict::new()),
+        Some(o) => o.as_dict().cloned(),
+    };
+    let Some(mut extensions) = dict_or_new(catalog.as_dict().and_then(|c| c.get(b"Extensions"))) else { return Ok(()) };
+    let Some(mut adbe) = dict_or_new(extensions.get(b"ADBE")) else { return Ok(()) };
+    if adbe.get(b"ExtensionLevel").map(|l| doc.resolve(l)).and_then(|l| l.as_int()).is_some_and(|l| l >= 1) {
+        return Ok(());
+    }
+    adbe.set(b"BaseVersion".to_vec(), Object::name("1.7"));
+    adbe.set(b"ExtensionLevel".to_vec(), Object::Int(1));
+    extensions.set(b"ADBE".to_vec(), Object::Dict(adbe));
+    doc.update_dict(root, |c| c.set(b"Extensions".to_vec(), Object::Dict(extensions)))?;
+    Ok(())
+}
+
+/// A document whose header and catalog `/Version` both say less than `min` gets `/Version min` in
+/// its catalog (§7.7.2: the later of the two applies).
+fn at_least_version(doc: &mut Document, min: &str) -> Result<(), AnnotError> {
+    let Some(root) = doc.root() else { return Ok(()) };
+    if !at_least(doc, min) {
+        doc.update_dict(root, |c| c.set(b"Version".to_vec(), Object::name(min)))?;
+    }
+    Ok(())
+}
+
+fn annotation_dict(new: &NewModel3d<'_>, rect: [f64; 4], page: ObjRef, stream: ObjRef, poster: ObjRef, meta: &Meta) -> Dict {
+    let mut d = Dict::new();
+    d.set(b"Type".to_vec(), Object::name("Annot"));
+    d.set(b"Subtype".to_vec(), Object::name("3D"));
+    d.set(b"Rect".to_vec(), num_array(&rect));
+    d.set(b"P".to_vec(), Object::Ref(page));
+    d.set(b"F".to_vec(), Object::Int(FLAG_PRINT));
+    if !new.contents.is_empty() {
+        d.set(b"Contents".to_vec(), PdfString::text(new.contents));
+    }
+    if !meta.id.is_empty() {
+        d.set(b"NM".to_vec(), PdfString::text(&meta.id));
+    }
+    if let Some(date) = &meta.date {
+        d.set(b"M".to_vec(), PdfString::literal(date.as_bytes().to_vec()));
+    }
+    d.set(b"3DD".to_vec(), Object::Ref(stream));
+    let mut activation = Dict::new();
+    activation.set(b"A".to_vec(), Object::name(new.activation.name()));
+    d.set(b"3DA".to_vec(), Object::Dict(activation));
+    let mut ap = Dict::new();
+    ap.set(b"N".to_vec(), Object::Ref(poster));
+    d.set(b"AP".to_vec(), Object::Dict(ap));
+    d
+}
+
+/// The poster drawing `p` into its box, which must lie within `rect`.
+fn picture_poster(rect: [f64; 4], p: &PosterPicture) -> Result<Stream, AnnotError> {
+    let at = normalize(p.at);
+    // A box fitted to `rect` in floating point can end a few ulps outside it: allow that, then clamp.
+    let slack = rect.iter().fold(1.0_f64, |m, v| m.max(v.abs())) * 1e-9;
+    let near = finite(&p.at) && at[0] >= rect[0] - slack && at[1] >= rect[1] - slack && at[2] <= rect[2] + slack && at[3] <= rect[3] + slack;
+    let at = [at[0].max(rect[0]), at[1].max(rect[1]), at[2].min(rect[2]), at[3].min(rect[3])];
+    if !(near && at[2] > at[0] && at[3] > at[1]) {
+        return Err(AnnotError::Invalid("the poster must fit inside the 3D model's rectangle".into()));
+    }
+    let place = appearance::picture_place(at, p.image, Some(p.size)).ok_or_else(|| AnnotError::Invalid("the poster picture has no size".into()))?;
+    let mut xobjects = Dict::new();
+    xobjects.set(b"Pic".to_vec(), Object::Ref(p.xobject));
+    let mut resources = Dict::new();
+    resources.set(b"XObject".to_vec(), Object::Dict(xobjects));
+    Ok(appearance::form(rect, format!("q {place} /Pic Do Q\n").as_bytes(), resources))
+}
+
+/// A light frame with "3D model" centred in it, shrunk to fit (left out when even 2 pt won't).
+fn placeholder_poster(rect: [f64; 4]) -> Stream {
+    let [x0, y0, x1, y1] = rect;
+    let (w, h) = (x1 - x0, y1 - y0);
+    let mut c =
+        format!("0.94 g {} {} {} {} re f\n0.45 G 1 w {} {} {} {} re S\n", n(x0), n(y0), n(w), n(h), n(x0 + 0.5), n(y0 + 0.5), n(w - 1.0), n(h - 1.0));
+    let mut resources = Dict::new();
+    let unit = appearance::text_width(PLACEHOLDER_LABEL, 1.0);
+    let size = if unit > 0.0 { (w * 0.8 / unit).min(h * 0.4).min(14.0) } else { 0.0 };
+    if size >= 2.0 {
+        let (tx, ty) = (x0 + (w - unit * size) / 2.0, y0 + (h - size * 0.7) / 2.0);
+        c.push_str(&format!("BT 0.3 g /Helv {} Tf {} {} Td ({PLACEHOLDER_LABEL}) Tj ET\n", n(size), n(tx), n(ty)));
+        resources.set(b"Font".to_vec(), appearance::helvetica_resource());
+    }
+    appearance::form(rect, c.as_bytes(), resources)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn model_size_is_capped() {
+        assert_eq!(check_model_size(&[0; 8], 8), Ok(()));
+        assert_eq!(check_model_size(&[0; 9], 8), Err(AnnotError::ModelTooLarge { size: 9, max: 8 }));
+    }
+
+    #[test]
+    fn the_format_is_read_from_the_header() {
+        assert_eq!(ModelFormat::detect(b"U3D\0rest"), Ok(ModelFormat::U3d));
+        assert_eq!(ModelFormat::detect(b"PRC8800"), Ok(ModelFormat::Prc));
+        for junk in [&b""[..], b"U3D", b"U3DX", b"PR", b"%PDF-1.7", b"prc"] {
+            assert_eq!(ModelFormat::detect(junk), Err(AnnotError::NotAModel), "{junk:?}");
+        }
+    }
+
+    #[test]
+    fn the_placeholder_label_shrinks_to_fit_and_is_dropped_when_it_cannot() {
+        let wide = String::from_utf8(placeholder_poster([0.0, 0.0, 300.0, 200.0]).decoded().unwrap().to_vec()).unwrap();
+        assert!(wide.contains("/Helv 14 Tf") && wide.contains("(3D model) Tj"), "{wide}");
+        let tiny = placeholder_poster([0.0, 0.0, 4.0, 4.0]);
+        assert!(!String::from_utf8(tiny.decoded().unwrap().to_vec()).unwrap().contains("Tj"));
+        assert!(tiny.dict.get(b"Resources").and_then(Object::as_dict).is_none_or(|r| r.get(b"Font").is_none()));
+    }
+}

crates/automation/src/bookmark_io.rs

@@ -0,0 +1,209 @@
+//! Bookmark trees in and out of documents: `bookmark_export`, `bookmark_import`, `bookmark_copy`.
+//!
+//! The portable form is JSON: `{"bookmarks": [node, …]}`, where a node is `title`, `page`
+//! (1-based, or `null` for one that goes nowhere), `view` (`{"type", "values"}`: a destination
+//! type and its values in PDF user space, as the file stores them), `color`, `bold`, `italic`,
+//! `open` and `children`. What export writes, import takes back unchanged. A file also carries
+//! `"truncated": true` when the export left out bookmarks nested past the listing limit.
+use crate::{Args, Automation, Result, ToolError, failed};
+use pdfcraft_engine::{DocId, Edit, OutlineNode};
+use serde_json::{Value, json};
+
+/// Deepest nesting a bookmark tree may have (the listing reaches 33 levels).
+const MAX_DEPTH: usize = 33;
+
+/// The keys a node may have: the ones [`node_json`] writes.
+const NODE_KEYS: [&str; 8] = ["title", "page", "view", "color", "bold", "italic", "open", "children"];
+
+impl Automation {
+    pub(crate) fn bookmark_export(&self, a: &Args) -> Result<Value> {
+        let id = self.doc(a)?.id;
+        let path = a.opt_path("path")?.unwrap_or_default();
+        let tree = self.outline_of(id, &path)?;
+        let mut out = json!({ "bookmarks": tree.nodes.iter().map(node_json).collect::<Vec<_>>(), "truncated": tree.truncated });
+        if let Some(file) = a.opt_str("out")? {
+            let target = self.resolve(file, true)?;
+            let mut saved = json!({ "bookmarks": out["bookmarks"] });
+            if tree.truncated {
+                saved["truncated"] = json!(true);
+            }
+            let text = serde_json::to_vec_pretty(&saved).map_err(failed)?;
+            crate::write_atomic(&target, &text)?;
+            out["path"] = json!(target);
+        }
+        Ok(out)
+    }
+
+    pub(crate) fn bookmark_import(&mut self, a: &Args) -> Result<Value> {
+        let (nodes, truncated) = match (a.get("bookmarks"), a.opt_str("file")?) {
+            (Some(list), None) => (nodes_of(list)?, false),
+            (None, Some(file)) => {
+                let path = self.resolve(file, false)?;
+                let value: Value = serde_json::from_slice(&crate::read_input(&path)?).map_err(|e| failed(format!("not a bookmark file: {e}")))?;
+                let list = value.get("bookmarks").ok_or_else(|| failed("not a bookmark file: it has no \"bookmarks\" list"))?;
+                (nodes_of(list)?, value.get("truncated") == Some(&Value::Bool(true)))
+            }
+            _ => return Err(ToolError::InvalidArgs("give either bookmarks or file".into())),
+        };
+        let mut out = self.write_tree(a, nodes)?;
+        out["truncated"] = json!(truncated);
+        Ok(out)
+    }
+
+    pub(crate) fn bookmark_copy(&mut self, a: &Args) -> Result<Value> {
+        let from = a.int("from")?;
+        let from = DocId(u64::try_from(from).map_err(|_| ToolError::InvalidArgs("from must be positive".into()))?);
+        let path = a.opt_path("path")?.unwrap_or_default();
+        let tree = self.outline_of(from, &path)?;
+        let mut out = self.write_tree(a, tree.nodes)?;
+        out["truncated"] = json!(tree.truncated);
+        Ok(out)
+    }
+
+    fn outline_of(&self, id: DocId, path: &[usize]) -> Result<pdfcraft_engine::OutlineTree> {
+        match self.session.outline_tree(id, path) {
+            // The engine names the path 0-based; the caller gave it 1-based.
+            Some(tree) => tree.map_err(|e| match e {
+                pdfcraft_organize::OutlineError::NoSuchBookmark(_) => failed(format!("there is no bookmark at {:?}", one_based(path))),
+                e => failed(e),
+            }),
+            None => Err(failed(format!("document {} is not open, or its bookmarks can't be read for editing", id.0))),
+        }
+    }
+
+    /// Write `nodes` into `doc` under `parent` at `position` (or in place of the outline with
+    /// `replace`), and say which of them went nowhere because the document lacks their page.
+    fn write_tree(&mut self, a: &Args, bookmarks: Vec<OutlineNode>) -> Result<Value> {
+        let parent = a.opt_path("parent")?.unwrap_or_default();
+        let index = a.opt_int("position")?.map_or(usize::MAX, |p| usize::try_from(p.max(1) - 1).unwrap_or(usize::MAX));
+        let replace = a.opt_bool("replace")?.unwrap_or(false);
+        let count = self.doc(a)?.info.pages.len();
+        let unmapped = pdfcraft_engine::outline_unmapped(&bookmarks, count);
+        let mut out = self.apply(a, Edit::ImportBookmarks { parent, index, bookmarks, replace })?;
+        out["unmapped"] = json!(unmapped.iter().map(|p| one_based(p)).collect::<Vec<_>>());
+        Ok(out)
+    }
+}
+
+fn one_based(path: &[usize]) -> Vec<usize> {
+    path.iter().map(|i| i.saturating_add(1)).collect()
+}
+
+/// A node as JSON, leaving out what is at its default (no view, black, regular, no children).
+fn node_json(n: &OutlineNode) -> Value {
+    let mut v = json!({ "title": n.title, "page": n.page.map(|p| p.saturating_add(1)), "open": n.open });
+    if let Some((kind, values)) = &n.view {
+        v["view"] = json!({ "type": String::from_utf8_lossy(kind), "values": values });
+    }
+    if let Some(c) = n.color {
+        v["color"] = json!(c);
+    }
+    if n.bold {
+        v["bold"] = json!(true);
+    }
+    if n.italic {
+        v["italic"] = json!(true);
+    }
+    if !n.children.is_empty() {
+        v["children"] = json!(n.children.iter().map(node_json).collect::<Vec<_>>());
+    }
+    v
+}
+
+fn nodes_of(list: &Value) -> Result<Vec<OutlineNode>> {
+    let mut count = 0;
+    list_of(list, &[], &mut count)
+}
+
+/// The nodes of one level; `at` is the 1-based path of their parent, for messages.
+fn list_of(list: &Value, at: &[usize], count: &mut usize) -> Result<Vec<OutlineNode>> {
+    let items = list.as_array().ok_or_else(|| bad(at, "children must be a list of bookmarks"))?;
+    if at.len() >= MAX_DEPTH && !items.is_empty() {
+        return Err(bad(at, &format!("bookmarks may nest at most {MAX_DEPTH} levels deep")));
+    }
+    *count = count.saturating_add(items.len());
+    if *count > pdfcraft_engine::MAX_IMPORT_BOOKMARKS {
+        return Err(ToolError::InvalidArgs(format!("at most {} bookmarks can be imported at once", pdfcraft_engine::MAX_IMPORT_BOOKMARKS)));
+    }
+    let mut out = Vec::with_capacity(items.len());
+    for (i, item) in items.iter().enumerate() {
+        let mut path = at.to_vec();
+        path.push(i.saturating_add(1));
+        out.push(node_of(item, &path, count)?);
+    }
+    Ok(out)
+}
+
+/// One node and, through [`list_of`], its children (recursion bounded by `MAX_DEPTH`).
+fn node_of(v: &Value, at: &[usize], count: &mut usize) -> Result<OutlineNode> {
+    let o = v.as_object().ok_or_else(|| bad(at, "must be an object"))?;
+    if let Some(k) = o.keys().find(|k| !NODE_KEYS.contains(&k.as_str())) {
+        return Err(bad(at, &format!("unknown key {k:?} (a bookmark has {})", NODE_KEYS.join(", "))));
+    }
+    let field = |k: &str| o.get(k).filter(|x| !x.is_null());
+    // An empty title is kept: files have them, and export writes them as "".
+    let title = field("title").and_then(Value::as_str).ok_or_else(|| bad(at, "needs a title"))?.to_string();
+    let page = match field("page") {
+        None => None,
+        Some(p) => Some(p.as_u64().filter(|p| *p >= 1).and_then(|p| usize::try_from(p - 1).ok()).ok_or_else(|| bad(at, "page must be 1 or more"))?),
+    };
+    let flag = |k: &str| field(k).map_or(Ok(None), |x| x.as_bool().map(Some).ok_or_else(|| bad(at, &format!("{k} must be true or false"))));
+    let color = match field("color") {
+        None => None,
+        Some(c) => {
+            let rgb: Option<Vec<f32>> = c.as_array().and_then(|c| c.iter().map(|x| x.as_f64().map(|x| x as f32)).collect());
+            match rgb.as_deref() {
+                Some(&[r, g, b]) if [r, g, b].iter().all(|c| (0.0..=1.0).contains(c)) => Some([r, g, b]),
+                _ => return Err(bad(at, "color must be [r, g, b], each from 0 to 1")),
+            }
+        }
+    };
+    let children = match field("children") {
+        None => Vec::new(),
+        Some(list) => list_of(list, at, count)?,
+    };
+    Ok(OutlineNode {
+        title,
+        page,
+        view: field("view").map(|x| view_of(x, at)).transpose()?,
+        color,
+        italic: flag("italic")?.unwrap_or(false),
+        bold: flag("bold")?.unwrap_or(false),
+        open: flag("open")?.unwrap_or(true),
+        children,
+    })
+}
+
+/// `{"type": "XYZ", "values": [left, top, zoom]}`: a destination type with exactly its values.
+fn view_of(v: &Value, at: &[usize]) -> Result<(Vec<u8>, Vec<Option<f64>>)> {
+    let kind = v.get("type").and_then(Value::as_str).ok_or_else(|| bad(at, "view needs a type such as XYZ or Fit"))?;
+    let values = match v.get("values").filter(|x| !x.is_null()) {
+        None => Vec::new(),
+        Some(list) => {
+            let list = list.as_array().filter(|l| l.len() <= 4).ok_or_else(|| bad(at, "view values must be a list of at most 4 numbers or nulls"))?;
+            list.iter()
+                .map(|x| match x {
+                    Value::Null => Ok(None),
+                    x => x.as_f64().map(Some).ok_or_else(|| bad(at, "view values must be numbers or null")),
+                })
+                .collect::<Result<_>>()?
+        }
+    };
+    let arity = pdfcraft_engine::outline_view_arity(kind.as_bytes()).ok_or_else(|| bad(at, VIEW_TYPES))?;
+    if values.len() != arity {
+        return Err(bad(at, &format!("a {kind} view takes {arity} values (numbers, or null to keep the reader's)")));
+    }
+    if kind == "FitR" && values.iter().any(Option::is_none) {
+        return Err(bad(at, "a FitR view needs all four values: left, bottom, right, top"));
+    }
+    Ok((kind.as_bytes().to_vec(), values))
+}
+
+const VIEW_TYPES: &str = "view type must be XYZ (3 values: left, top, zoom), Fit, FitB (none), FitH, FitV, FitBH, FitBV (1) or FitR (4)";
+
+fn bad(at: &[usize], what: &str) -> ToolError {
+    if at.is_empty() {
+        return ToolError::InvalidArgs(format!("bookmarks: {what}"));
+    }
+    ToolError::InvalidArgs(format!("bookmark {at:?}: {what}"))
+}

crates/automation/src/comments.rs

@@ -75,7 +75,7 @@ fn to_user(p: &PageInfo, x: f64, y: f64) -> [f64; 2] {
     [ux as f64, uy as f64]
 }
 
-fn rect_to_user(p: &PageInfo, r: [f64; 4]) -> [f64; 4] {
+pub(crate) fn rect_to_user(p: &PageInfo, r: [f64; 4]) -> [f64; 4] {
     let (a, b) = (to_user(p, r[0], r[1]), to_user(p, r[2], r[3]));
     [a[0].min(b[0]), a[1].min(b[1]), a[0].max(b[0]), a[1].max(b[1])]
 }

crates/automation/src/dispatch.rs

@@ -197,6 +197,9 @@ impl Automation {
                 out
             }
             "bookmark_list" => self.bookmark_listing(&a)?,
+            "bookmark_export" => self.bookmark_export(&a)?,
+            "bookmark_import" => self.bookmark_import(&a)?,
+            "bookmark_copy" => self.bookmark_copy(&a)?,
             "bookmark_add" => {
                 let page = self.page(&a)?;
                 let parent = a.opt_path("parent")?.unwrap_or_default();
@@ -770,6 +773,7 @@ impl Automation {
             "comment_list" => self.comment_list(&a)?,
             "comment_add" => self.comment_add(&a)?,
             "stamp_custom" => self.stamp_custom(&a)?,
+            "model_add" => self.model_add(&a)?,
             "comment_reply" => self.comment_reply(&a)?,
             "comment_set_status" => self.comment_set_status(&a)?,
             "sign_list" => self.sign_list(&a)?,

crates/automation/src/file_access.rs

@@ -394,8 +394,18 @@ mod tests {
         // Helpers that are only called with a resolved path. `doc_batch` (batch.rs) resolves its
         // inputs and out_dir, walks only inside them (skipping links) and resolves every
         // discovered file again before `process` reads it or `publish` writes it.
-        const RESOLVED_BY_CALLER: &[&str] =
-            &["write_atomic", "write_atomic_with", "read_input", "read_input_bytes", "read_review_sidecar", "process", "linked", "walk", "publish"];
+        const RESOLVED_BY_CALLER: &[&str] = &[
+            "write_atomic",
+            "write_atomic_with",
+            "read_input",
+            "read_input_bytes",
+            "read_model",
+            "read_review_sidecar",
+            "process",
+            "linked",
+            "walk",
+            "publish",
+        ];
         let mut dirs = vec![Path::new(env!("CARGO_MANIFEST_DIR")).join("src")];
         let mut files = vec![];
         while let Some(dir) = dirs.pop() {

crates/automation/src/lib.rs

@@ -27,6 +27,7 @@ mod links;
 #[cfg(feature = "mcp")]
 pub mod mcp;
 mod measure;
+mod model3d;
 mod model_render;
 mod printing;
 mod reading;
@@ -51,6 +52,7 @@ use file_access::foreign_share;
 use text_cache::TextCache;
 
 mod assemble;
+mod bookmark_io;
 mod dispatch;
 mod documents;
 mod error;

crates/automation/src/mcp.rs

@@ -557,7 +557,7 @@ fn tool_json(t: &crate::ToolDef) -> Value {
         "title": t.title,
         "description": t.description,
         "inputSchema": t.input_schema,
-        "annotations": { "title": t.title, "readOnlyHint": t.read_only, "destructiveHint": t.destructive, "idempotentHint": t.read_only || matches!(t.name, "doc_save" | "doc_optimize" | "doc_export_data" | "measure_export" | "doc_export_images" | "doc_export_office" | "doc_export_all_images" | "doc_export_text" | "image_save"), "openWorldHint": false },
+        "annotations": { "title": t.title, "readOnlyHint": t.read_only, "destructiveHint": t.destructive, "idempotentHint": t.read_only || matches!(t.name, "doc_save" | "doc_optimize" | "doc_export_data" | "measure_export" | "doc_export_images" | "doc_export_office" | "doc_export_all_images" | "doc_export_text" | "image_save" | "bookmark_export"), "openWorldHint": false },
     })
 }
 

crates/automation/src/model3d.rs

@@ -0,0 +1,114 @@
+//! 3D model tools (Acrobat: Rich Media ▸ Add 3D, AGENTS.md §3).
+
+use std::path::Path;
+
+use pdfcraft_engine::{Activation3d, Edit, MAX_3D_MODEL_BYTES, MarkFile, Model3dFormat};
+use serde_json::Value;
+
+use crate::comments::rect_to_user;
+use crate::{Args, Automation, Result, ToolError, failed};
+
+/// The largest side of a 3D model's box, in points: the largest page PDF allows (ISO 32000-2 Annex C).
+const MAX_MODEL_SIDE: f64 = 14_400.0;
+
+impl Automation {
+    /// A U3D or PRC model in `rect` on `page`, its poster the picture at `poster` (a PDF page or an
+    /// image) fitted inside the box, or a labelled frame.
+    pub(crate) fn model_add(&mut self, a: &Args) -> Result<Value> {
+        let page = self.page(a)?;
+        let info = self.doc(a)?.info.pages.get(page).cloned().ok_or_else(|| ToolError::InvalidArgs(format!("page {} does not exist", page + 1)))?;
+        let r = a.nums::<4>("rect")?.ok_or_else(|| ToolError::InvalidArgs("missing argument rect".into()))?;
+        let (w, h) = ((r[2] - r[0]).abs(), (r[3] - r[1]).abs());
+        if !((1.0..=MAX_MODEL_SIDE).contains(&w) && (1.0..=MAX_MODEL_SIDE).contains(&h)) {
+            return Err(ToolError::InvalidArgs(format!(
+                "rect must be [x0, y0, x1, y1] with each side at least 1 pt and at most {MAX_MODEL_SIDE} pt"
+            )));
+        }
+        let activation = match a.opt_str("activation")? {
+            None => Activation3d::default(),
+            Some(word) => Activation3d::ALL
+                .iter()
+                .find(|(_, w)| *w == word)
+                .map(|(act, _)| *act)
+                .ok_or_else(|| ToolError::InvalidArgs(format!("activation must be one of: {}", Activation3d::ALL.map(|(_, w)| w).join(", "))))?,
+        };
+        let path = self.resolve(a.str("path")?, false)?;
+        let model = read_model(&path, MAX_3D_MODEL_BYTES)?;
+        let file = path.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default();
+        let name = a.opt_str("name")?.map(str::to_owned).unwrap_or_else(|| file.rsplit_once('.').map_or(file.clone(), |(s, _)| s.to_owned()));
+        let poster = match a.opt_str("poster")? {
+            None => None,
+            Some(p) => {
+                let path = self.resolve(p, false)?;
+                let bytes = crate::read_input(&path)?;
+                let name = path.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default();
+                let page = usize::try_from(a.opt_int("poster_page")?.unwrap_or(1).max(1)).unwrap_or(1).saturating_sub(1);
+                Some(MarkFile { name, bytes: std::sync::Arc::new(bytes), page })
+            }
+        };
+        let edit = Edit::AddModel3d { page, rect: rect_to_user(&info, r), model: std::sync::Arc::new(model), poster, activation, name };
+        self.apply(a, edit)
+    }
+}
+
+/// Read a resolved model file of at most `max` bytes. Its size (from the file system) and its first
+/// bytes are checked before the rest is read, so a large file that is not a model is never loaded.
+fn read_model(path: &Path, max: usize) -> Result<Vec<u8>> {
+    use std::io::Read as _;
+    let io = |e: std::io::Error| failed(format!("{}: {e}", path.display()));
+    let too_large = |size: u64| failed(format!("the 3D model is {size} bytes; the largest accepted is {max}"));
+    let cap = u64::try_from(max).unwrap_or(u64::MAX);
+    let mut file = std::fs::File::open(path).map_err(io)?;
+    if let Ok(meta) = file.metadata()
+        && meta.is_file()
+        && meta.len() > cap
+    {
+        return Err(too_large(meta.len()));
+    }
+    let mut bytes = Vec::new();
+    (&mut file).take(4).read_to_end(&mut bytes).map_err(io)?;
+    Model3dFormat::detect(&bytes).map_err(failed)?;
+    let rest = cap.saturating_add(1).saturating_sub(bytes.len() as u64);
+    file.take(rest).read_to_end(&mut bytes).map_err(io)?;
+    if bytes.len() > max {
+        return Err(failed(format!("the 3D model is more than {max} bytes, the largest accepted")));
+    }
+    Ok(bytes)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn file(dir: &Path, name: &str, bytes: &[u8]) -> std::path::PathBuf {
+        let path = dir.join(name);
+        std::fs::write(&path, bytes).unwrap();
+        path
+    }
+
+    #[test]
+    fn a_model_is_read_whole_when_it_fits() {
+        let dir = tempfile::tempdir().unwrap();
+        let mut prc = b"PRC".to_vec();
+        prc.extend_from_slice(&[7; 40]);
+        assert_eq!(read_model(&file(dir.path(), "m.prc", &prc), 64).unwrap(), prc);
+        assert_eq!(read_model(&file(dir.path(), "m.u3d", b"U3D\0x"), 6).unwrap(), b"U3D\0x");
+    }
+
+    #[test]
+    fn a_model_past_the_cap_is_refused_by_its_size_before_it_is_read() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = file(dir.path(), "big.prc", &[b'P', b'R', b'C', 0, 0, 0, 0, 0, 0, 0]);
+        let err = read_model(&path, 4).unwrap_err().to_string();
+        assert!(err.contains("is 10 bytes") && err.contains("largest accepted is 4"), "the file's own size, from the file system: {err}");
+    }
+
+    #[test]
+    fn a_file_that_is_not_a_model_is_refused_by_its_header() {
+        let dir = tempfile::tempdir().unwrap();
+        for junk in [&b"%PDF-1.7 a page"[..], b"PR", b"", b"U3DX and more"] {
+            let err = read_model(&file(dir.path(), "junk.bin", junk), 64).unwrap_err().to_string();
+            assert!(err.contains("not a 3D model"), "{junk:?}: {err}");
+        }
+    }
+}

crates/automation/src/tools.rs

@@ -330,6 +330,50 @@ pub fn tools() -> Vec<ToolDef> {
             }),
             &["doc", "title", "page"],
         )),
+        t(
+            "bookmark_export",
+            "Export bookmarks",
+            "The bookmark tree, or the subtree at path, as a list of nodes bookmark_import takes back unchanged. A node has title, page (1-based, null when it goes nowhere), open, and when set view ({type, values}: a destination type from ISO 32000-2 §12.3.2.2 Table 149 and its values in PDF user space, as the file stores them), color ([r, g, b], 0-1), bold, italic and children. truncated is true when bookmarks nested deeper than 33 levels were left out. With out, the tree is also written there as a JSON file {\"bookmarks\": [...]}, with \"truncated\": true when that is so; out is overwritten.",
+        )
+        .destructive()
+        .with(schema(
+            json!({ "doc": doc(), "path": path("The bookmark whose subtree to export (omit for the whole outline)"), "out": path_arg() }),
+            &["doc"],
+        )),
+        t(
+            "bookmark_import",
+            "Import bookmarks",
+            "Add a tree of bookmarks, as bookmark_export gives it (bookmarks) or as a JSON file it wrote (file), under a parent bookmark (or at the top level) at a position, or with replace in place of the whole outline. A bookmark whose page this document lacks is kept without a destination and listed in unmapped (1-based paths into the given tree). A view takes exactly its type's values (XYZ 3, FitR 4, FitH/FitV/FitBH/FitBV 1, Fit/FitB none). Give exactly one of bookmarks and file. A title may be empty but not missing; a key a node does not have is refused. Every node is checked before anything is written: at most 100000 bookmarks, nested at most 33 levels counting the parent's. truncated is true when the file says its export left bookmarks out. Undoable.",
+        )
+        .destructive()
+        .with(schema(
+            json!({
+                "doc": doc(),
+                "bookmarks": { "type": "array", "items": { "type": "object" }, "minItems": 1, "description": "Nodes as bookmark_export returns them." },
+                "file": path_arg(),
+                "parent": path("Parent bookmark (omit for the top level)"),
+                "position": { "type": "integer", "minimum": 1, "description": "1-based position among the parent's children (default: last)." },
+                "replace": { "type": "boolean", "description": "Replace the document's bookmarks instead of adding to them (default false; leave parent out)." }
+            }),
+            &["doc"],
+        )),
+        t(
+            "bookmark_copy",
+            "Copy bookmarks from another document",
+            "Copy the bookmarks of document from (or the subtree at path) into doc, by page number: under a parent bookmark (or at the top level) at a position, or with replace in place of doc's outline. A bookmark whose page doc lacks is kept without a destination and listed in unmapped (1-based paths into the copied tree). truncated is true when bookmarks nested deeper than 33 levels were left out of the copy. Undoable.",
+        )
+        .destructive()
+        .with(schema(
+            json!({
+                "doc": doc(),
+                "from": { "type": "integer", "minimum": 1, "description": "Id of the document to copy from." },
+                "path": path("The bookmark whose subtree to copy (omit for the whole outline)"),
+                "parent": path("Parent bookmark in doc (omit for the top level)"),
+                "position": { "type": "integer", "minimum": 1, "description": "1-based position among the parent's children (default: last)." },
+                "replace": { "type": "boolean", "description": "Replace doc's bookmarks instead of adding to them (default false; leave parent out)." }
+            }),
+            &["doc", "from"],
+        )),
         t("bookmark_rename", "Rename a bookmark", "Change a bookmark's title. Undoable.")
             .with(schema(json!({ "doc": doc(), "path": path("The bookmark"), "title": { "type": "string", "minLength": 1 } }), &["doc", "path", "title"])),
         t("bookmark_delete", "Delete a bookmark", "Delete a bookmark and the bookmarks under it. Undoable.")
@@ -476,6 +520,20 @@ pub fn tools() -> Vec<ToolDef> {
                 }),
                 &["doc", "page", "path"],
             )),
+        t("model_add", "Add a 3D model", "Add a 3D model (Acrobat: Rich Media ▸ Add 3D): the U3D or PRC file at path, recognised by its first bytes, as a 3D annotation in rect [x0, y0, x1, y1] (points from the top-left of the displayed page; each side 1–14400 pt; at most 256 MiB). Its poster, what prints and what readers show until the model is activated, is the picture at poster (a PDF page, poster_page default 1, or an image) fitted inside rect keeping its shape and centred; without poster, a frame labelled \"3D model\". activation: click (default), page_open or page_visible. name is its description (default: the file name). No views are added: readers open the model on its own default view. Undoable.")
+            .with(schema(
+                json!({
+                    "doc": doc(),
+                    "page": { "type": "integer", "minimum": 1 },
+                    "path": { "type": "string" },
+                    "rect": { "type": "array", "items": { "type": "number" }, "minItems": 4, "maxItems": 4 },
+                    "poster": { "type": "string" },
+                    "poster_page": { "type": "integer", "minimum": 1 },
+                    "activation": { "type": "string", "enum": ["click", "page_open", "page_visible"] },
+                    "name": { "type": "string" },
+                }),
+                &["doc", "page", "path", "rect"],
+            )),
         t("form_set_image", "Set an image field's picture", "Show an image file (PNG, JPEG, TIFF, GIF or BMP) in an image field or button, scaled to fit and centred (what clicking an image field does). On an XFA form the picture is kept in its data too (base64, as Designer saves it) and the form shows it from there. Undoable.")
             .with(schema(json!({ "doc": doc(), "field": { "type": "string" }, "path": { "type": "string" } }), &["doc", "field", "path"])),
         t(
@@ -1466,7 +1524,7 @@ pub fn tools() -> Vec<ToolDef> {
             .with(schema(json!({ "doc": doc() }), &["doc"])),
         t("doc_open_revision", "Open a revision", "Open saved revision `revision` (1 = the oldest) of a document as a new, unsaved document, to see the file as it was then.")
             .with(schema(json!({ "doc": doc(), "revision": { "type": "integer", "minimum": 1 } }), &["doc", "revision"])),
-        t("doc_optimize", "Optimize PDF", "Write an optimized copy to `path` (Acrobat's PDF Optimizer). preset: standard (default; Reduce File Size's choices) or mobile (images to 96 ppi above 144, JPEG high quality); the options below change it. compatibility: retain (default; keeps the document's version, or 1.5 when object streams are written), 1.4, 1.5, 1.6, 1.7 or 2.0. merge_fragments (default true) first puts a page picture drawn as many stacked image strips (as some PDF printers write it) back together into one image, so it can be resampled (merged_images, fragments_merged). color / gray: { downsample, ppi, above_ppi, compression: jpeg|zip|retain, quality 1–100 } (defaults: downsample to 150 ppi above 225, JPEG 60). mono: { downsample, ppi, above_ppi, compression: ccitt_g4|jbig2|retain } for black-and-white images and image masks (default: averaged down to 300 ppi above 450 ppi, counted in images_resampled; stored losslessly as CCITT Group 4 or JBIG2 (or 1-bit Flate, once resampled or packed from more bits) when that is smaller, Group 3 fax images, JBIG2 images, black-and-white RGB and indexed images using only palette entries 0 and 1 among them, counted in images_recompressed; retain resamples only, a CCITT image staying CCITT, a JBIG2 image JBIG2 and any other becoming Flate). Images past what one run may decode stay as they are, counted in images_refused; streams it only stores with Flate past that stay LZW, uncounted. Images are measured where pages draw them and replaced only when smaller. discard_*: thumbnails (default true), alternate_images (true), tags, print_settings; flate_unencoded (true); object_streams (default true; always off for 1.4); lzw_to_flate (true) decodes LZW streams and stores them with Flate instead, leaving any it cannot decode unchanged (lzw_streams counts the streams converted); remove_invalid_links and remove_unreferenced_dests (true); images and forms the pages list but never draw are always dropped (unused_xobjects). discard: Remove Hidden Information categories (metadata, attachments, comments, form-fields, hidden-text, hidden-layers, bookmarks, links-actions-scripts, private-data). Signed documents are refused. The open document is unchanged.")
+        t("doc_optimize", "Optimize PDF", "Write an optimized copy to `path` (Acrobat's PDF Optimizer). preset: standard (default; Reduce File Size's choices) or mobile (images to 96 ppi above 144, JPEG high quality); the options below change it. compatibility: retain (default; keeps the document's version, or 1.5 when object streams are written), 1.4, 1.5, 1.6, 1.7 or 2.0. merge_fragments (default true) first puts a page picture drawn as many stacked image strips (as some PDF printers write it) back together into one image, so it can be resampled (merged_images, fragments_merged). color / gray: { downsample, ppi, above_ppi, compression: jpeg|zip|retain, quality 1–100 } (defaults: downsample to 150 ppi above 225, JPEG 60). mono: { downsample, ppi, above_ppi, compression: ccitt_g4|jbig2|retain } for black-and-white images and image masks (default: averaged down to 300 ppi above 450 ppi, counted in images_resampled; stored losslessly as CCITT Group 4 or JBIG2 (or 1-bit Flate, once resampled or packed from more bits) when that is smaller, up to 16 JBIG2 images sharing one symbol dictionary (/JBIG2Globals) where that is smaller still (image masks and DeviceGray images named directly, of at most 64 Mi pixels, which redaction can store again without it), Group 3 fax images, JBIG2 images, black-and-white RGB and indexed images using only palette entries 0 and 1 among them, counted in images_recompressed; retain resamples only, a CCITT image staying CCITT, a JBIG2 image JBIG2 and any other becoming Flate). Images past what one run may decode stay as they are, counted in images_refused; streams it only stores with Flate past that stay LZW, uncounted. Images are measured where pages draw them and replaced only when smaller. discard_*: thumbnails (default true), alternate_images (true), tags, print_settings; flate_unencoded (true); object_streams (default true; always off for 1.4); lzw_to_flate (true) decodes LZW streams and stores them with Flate instead, leaving any it cannot decode unchanged (lzw_streams counts the streams converted); remove_invalid_links and remove_unreferenced_dests (true); images and forms the pages list but never draw are always dropped (unused_xobjects). discard: Remove Hidden Information categories (metadata, attachments, comments, form-fields, hidden-text, hidden-layers, bookmarks, links-actions-scripts, private-data). Signed documents are refused. The open document is unchanged.")
             .cmd("optimize.advanced")
             .with(schema(
                 json!({

crates/automation/tests/it/automation.rs

@@ -10194,6 +10194,31 @@ fn changing_a_lists_options_through_tools_keeps_its_saved_selection_on_the_same_
     assert_eq!(saved_selection_indices(&dir.join("letters.pdf"), "letters"), Some(vec![0, 1]), "B and C are now items 0 and 1");
 }
 
+/// Clearing a field's length limit through `form_set_props` (`"max_length": 0`) leaves it with
+/// none, even when its parent field has one it would otherwise inherit.
+#[test]
+fn clearing_a_kids_length_limit_through_tools_does_not_bring_back_its_parents() {
+    let objs = [
+        "<< /Type /Catalog /Pages 2 0 R /AcroForm 4 0 R >>",
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 400 300] >>",
+        "<< /Type /Page /Parent 2 0 R /Annots [6 0 R] >>",
+        "<< /Fields [5 0 R] /DA (/Helv 12 Tf 0 g) /DR << /Font << /Helv 7 0 R >> >> >>",
+        "<< /T (address) /FT /Tx /MaxLen 3 /Kids [6 0 R] >>",
+        "<< /Type /Annot /Subtype /Widget /T (city) /Parent 5 0 R /MaxLen 8 /Rect [10 250 150 268] /P 3 0 R >>",
+        "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>",
+    ];
+    let dir = workdir("kid-max-len");
+    std::fs::write(dir.join("form.pdf"), pdf_of(&objs)).unwrap();
+    let mut a = auto(&dir);
+    let doc = ok(&mut a, "doc_open", json!({ "path": "form.pdf" }))["doc"].as_u64().unwrap();
+    ok(&mut a, "form_set_props", json!({ "doc": doc, "field": "address.city", "max_length": 0 }));
+    ok(&mut a, "form_fill", json!({ "doc": doc, "values": { "address.city": "Absalom" } }));
+    let fields = ok(&mut a, "form_fields", json!({ "doc": doc }));
+    let city = fields["fields"].as_array().unwrap().iter().find(|f| f["name"] == "address.city").unwrap().clone();
+    assert!(city.get("max_length").is_none(), "no limit, not the parent's 3: {city}");
+    assert_eq!(city["value"], "Absalom", "the value is not cut to the parent's 3 characters");
+}
+
 /// Clearing a field's default through `form_set_props` (`"default": ""`) leaves it with none,
 /// even when its parent field has one it would otherwise inherit.
 #[test]
@@ -10642,3 +10667,168 @@ fn multiline_fill_sign_engine_round_trip_preserves_lines_and_appearance() {
     assert_eq!(rendered, re.call("page_render", &json!({"doc":reopened,"page":1,"dpi":72})).unwrap(), "saved appearances are identical");
     std::fs::remove_dir_all(dir).unwrap();
 }
+
+/// Export, then import into another document and copy between open documents: the tree comes
+/// back unchanged, a page the target lacks is reported, and the import undoes in one step.
+#[test]
+fn bookmarks_export_import_and_copy_between_documents() {
+    let dir = workdir("bookmark-io");
+    let mut a = auto(&dir);
+    let src = ok(&mut a, "doc_open", json!({ "path": "a.pdf" }))["doc"].as_u64().unwrap();
+    ok(&mut a, "bookmark_add", json!({ "doc": src, "title": "Intro", "page": 1 }));
+    ok(&mut a, "bookmark_add", json!({ "doc": src, "title": "Detail", "page": 3, "parent": [1] }));
+    ok(&mut a, "bookmark_add", json!({ "doc": src, "title": "End", "page": 2 }));
+    ok(&mut a, "bookmark_set_style", json!({ "doc": src, "path": [1], "color": [1, 0, 0], "bold": true }));
+    let exported = ok(&mut a, "bookmark_export", json!({ "doc": src, "out": "marks.json" }));
+    assert_eq!(exported["truncated"], false);
+    let tree = exported["bookmarks"].clone();
+    assert_eq!((tree[0]["title"].clone(), tree[0]["color"].clone(), tree[0]["bold"].clone()), (json!("Intro"), json!([1.0, 0.0, 0.0]), json!(true)));
+    assert_eq!((tree[0]["children"][0]["title"].clone(), tree[0]["children"][0]["page"].clone()), (json!("Detail"), json!(3)));
+    assert_eq!(tree[0]["view"]["type"], "XYZ");
+    let subtree = ok(&mut a, "bookmark_export", json!({ "doc": src, "path": [1, 1] }))["bookmarks"].clone();
+    assert_eq!(subtree, json!([tree[0]["children"][0]]));
+
+    // b.pdf has two pages: Detail goes to the third, so it arrives without a destination.
+    let dst = ok(&mut a, "doc_open", json!({ "path": "b.pdf" }))["doc"].as_u64().unwrap();
+    let imported = ok(&mut a, "bookmark_import", json!({ "doc": dst, "file": "marks.json" }));
+    assert_eq!(imported["unmapped"], json!([[1, 1]]));
+    let back = ok(&mut a, "bookmark_export", json!({ "doc": dst }))["bookmarks"].clone();
+    assert_eq!(back[0]["children"][0]["page"], json!(null));
+    assert_eq!((back[0]["title"].clone(), back[1].clone()), (tree[0]["title"].clone(), tree[1].clone()));
+    ok(&mut a, "edit_undo", json!({ "doc": dst }));
+    assert_eq!(ok(&mut a, "bookmark_list", json!({ "doc": dst }))["bookmarks"], json!([]));
+
+    // Into a document with every page, the tree is unchanged, wherever it is copied from.
+    let same = ok(&mut a, "doc_open", json!({ "path": "a.pdf" }))["doc"].as_u64().unwrap();
+    ok(&mut a, "bookmark_add", json!({ "doc": same, "title": "Old", "page": 1 }));
+    let copied = ok(&mut a, "bookmark_copy", json!({ "doc": same, "from": src, "replace": true }));
+    assert_eq!(copied["unmapped"], json!([]));
+    assert_eq!(ok(&mut a, "bookmark_export", json!({ "doc": same }))["bookmarks"], tree);
+    ok(&mut a, "bookmark_import", json!({ "doc": same, "bookmarks": subtree, "parent": [2], "position": 1 }));
+    assert_eq!(ok(&mut a, "bookmark_list", json!({ "doc": same }))["bookmarks"][1]["children"][0]["title"], "Detail");
+}
+
+/// A one-page document whose outline has an untitled item, a /FitR destination with three of
+/// its four numbers, and a chain nested `deep` levels below them.
+fn odd_outline(deep: usize) -> Vec<u8> {
+    let first_deep = 7;
+    let mut objs = vec![
+        "<< /Type /Catalog /Pages 2 0 R /Outlines 4 0 R >>".to_string(),
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 200 300] >>".into(),
+        "<< /Type /Page /Parent 2 0 R >>".into(),
+        "<< /Type /Outlines /First 5 0 R /Last 6 0 R >>".into(),
+        "<< /Title () /Parent 4 0 R /Next 6 0 R /Dest [3 0 R /Fit] >>".into(),
+        format!(
+            "<< /Title (Short) /Parent 4 0 R /Prev 5 0 R /Dest [3 0 R /FitR 0 0 10]{} >>",
+            if deep > 0 { format!(" /First {first_deep} 0 R /Last {first_deep} 0 R") } else { String::new() }
+        ),
+    ];
+    for i in 0..deep {
+        let (me, parent) = (first_deep + i, if i == 0 { 6 } else { first_deep + i - 1 });
+        let child = if i + 1 < deep { format!(" /First {0} 0 R /Last {0} 0 R", me + 1) } else { String::new() };
+        objs.push(format!("<< /Title (Level) /Parent {parent} 0 R /Dest [3 0 R /Fit]{child} >>"));
+    }
+    pdf_of(&objs.iter().map(String::as_str).collect::<Vec<_>>())
+}
+
+/// What a real file holds and the JSON form can't say exactly still copies and round-trips: an
+/// empty title stays empty, a short /FitR keeps its page and drops the view, and bookmarks past
+/// the listing depth are reported as left out at every step.
+#[test]
+fn odd_bookmarks_round_trip_and_a_cut_tree_says_so() {
+    let dir = workdir("bookmark-io-odd");
+    std::fs::write(dir.join("odd.pdf"), odd_outline(0)).unwrap();
+    std::fs::write(dir.join("deep.pdf"), odd_outline(40)).unwrap();
+    let mut a = auto(&dir);
+    let src = ok(&mut a, "doc_open", json!({ "path": "odd.pdf" }))["doc"].as_u64().unwrap();
+    let tree = ok(&mut a, "bookmark_export", json!({ "doc": src, "out": "odd.json" }))["bookmarks"].clone();
+    assert_eq!((tree[0]["title"].clone(), tree[1]["page"].clone(), tree[1].get("view")), (json!(""), json!(1), None));
+    let dst = ok(&mut a, "doc_open", json!({ "path": "b.pdf" }))["doc"].as_u64().unwrap();
+    assert_eq!(ok(&mut a, "bookmark_import", json!({ "doc": dst, "file": "odd.json", "replace": true }))["truncated"], false);
+    // A destination with no view is written as XYZ with nulls: the same page, the reader's view.
+    let back = ok(&mut a, "bookmark_export", json!({ "doc": dst }))["bookmarks"].clone();
+    assert_eq!((back[0].clone(), back[1]["title"].clone(), back[1]["page"].clone()), (tree[0].clone(), json!("Short"), json!(1)));
+    assert_eq!(back[1]["view"], json!({ "type": "XYZ", "values": [null, null, null] }));
+    let copied = ok(&mut a, "bookmark_copy", json!({ "doc": dst, "from": src, "replace": true }));
+    assert_eq!((copied["unmapped"].clone(), copied["truncated"].clone()), (json!([]), json!(false)));
+    match a.call("bookmark_export", &json!({ "doc": src, "path": [3] })) {
+        Err(ToolError::Failed(m)) => assert!(m.contains("no bookmark at [3]"), "{m}"),
+        other => panic!("expected no bookmark, got {other:?}"),
+    }
+
+    let deep = ok(&mut a, "doc_open", json!({ "path": "deep.pdf" }))["doc"].as_u64().unwrap();
+    assert_eq!(ok(&mut a, "bookmark_export", json!({ "doc": deep, "out": "deep.json" }))["truncated"], true);
+    let saved: Value = serde_json::from_slice(&std::fs::read(dir.join("deep.json")).unwrap()).unwrap();
+    assert_eq!(saved["truncated"], true);
+    assert_eq!(ok(&mut a, "bookmark_import", json!({ "doc": dst, "file": "deep.json", "replace": true }))["truncated"], true);
+    assert_eq!(ok(&mut a, "bookmark_copy", json!({ "doc": dst, "from": deep, "replace": true }))["truncated"], true);
+    let export = tools().into_iter().find(|t| t.name == "bookmark_export").unwrap();
+    assert!(export.destructive && !export.read_only, "bookmark_export overwrites out");
+    std::fs::remove_dir_all(dir).unwrap();
+}
+
+#[test]
+fn a_misspelt_bookmark_key_is_refused_not_dropped() {
+    let dir = workdir("bookmark-io-key");
+    let mut a = auto(&dir);
+    let doc = ok(&mut a, "doc_open", json!({ "path": "a.pdf" }))["doc"].as_u64().unwrap();
+    let tree = json!([{ "title": "Parent", "children": [{ "title": "Red", "page": 1, "colour": [1, 0, 0] }] }]);
+    match a.call("bookmark_import", &json!({ "doc": doc, "bookmarks": tree })) {
+        Err(ToolError::InvalidArgs(m)) => assert!(m.contains("[1, 1]") && m.contains("\"colour\""), "{m}"),
+        other => panic!("expected InvalidArgs, got {other:?}"),
+    }
+    assert_eq!(ok(&mut a, "bookmark_list", json!({ "doc": doc }))["bookmarks"], json!([]));
+    std::fs::remove_dir_all(dir).unwrap();
+}
+
+#[test]
+fn a_bad_bookmark_tree_is_refused_whole_and_names_the_node() {
+    let dir = workdir("bookmark-io-bad");
+    let mut a = auto(&dir);
+    let doc = ok(&mut a, "doc_open", json!({ "path": "a.pdf" }))["doc"].as_u64().unwrap();
+    let refused = |a: &mut Automation, bookmarks: Value| match a.call("bookmark_import", &json!({ "doc": doc, "bookmarks": bookmarks })) {
+        Err(ToolError::InvalidArgs(m)) => m,
+        other => panic!("expected InvalidArgs, got {other:?}"),
+    };
+    let fine = json!({ "title": "Fine", "page": 1 });
+    let m = refused(&mut a, json!([fine, { "title": "Parent", "children": [{ "page": 1 }] }]));
+    assert!(m.contains("[2, 1]") && m.contains("title"), "{m}");
+    let m = refused(&mut a, json!([{ "title": 5 }]));
+    assert!(m.contains("[1]") && m.contains("title"), "{m}");
+    let m = refused(&mut a, json!([fine, { "title": "Bad", "page": 0 }]));
+    assert!(m.contains("[2]") && m.contains("page"), "{m}");
+    let m = refused(&mut a, json!([{ "title": "Bad", "color": [2, 0, 0] }]));
+    assert!(m.contains("color"), "{m}");
+    let m = refused(&mut a, json!([{ "title": "Bad", "view": { "type": "XYZ", "values": [1, 2, 3, 4, 5] } }]));
+    assert!(m.contains("view"), "{m}");
+    let mut deep = json!({ "title": "Leaf" });
+    for _ in 0..40 {
+        deep = json!({ "title": "Level", "children": [deep] });
+    }
+    assert!(refused(&mut a, json!([deep])).contains("33 levels"));
+    let m = refused(&mut a, json!([fine, { "title": "Z", "page": 1, "view": { "type": "Zoom" } }]));
+    assert!(m.contains("[2]") && m.contains("XYZ (3 values"), "{m}");
+    let m = refused(&mut a, json!([fine, { "title": "Z", "page": 1, "view": { "type": "FitH", "values": [1, 2] } }]));
+    assert!(m.contains("[2]") && m.contains("FitH view takes 1"), "{m}");
+    let m = refused(&mut a, json!([{ "title": "R", "view": { "type": "FitR", "values": [0, null, 1, 1] } }]));
+    assert!(m.contains("all four"), "{m}");
+    assert!(matches!(a.call("bookmark_import", &json!({ "doc": doc })), Err(ToolError::InvalidArgs(_))));
+    assert!(matches!(a.call("bookmark_import", &json!({ "doc": doc, "bookmarks": [fine], "file": "x.json" })), Err(ToolError::InvalidArgs(_))));
+    // A real bookmark file outside the root is refused for being outside, not for being missing.
+    let outside = dir.with_extension("outside.json");
+    std::fs::write(&outside, br#"{"bookmarks": [{"title": "Outside", "page": 1}]}"#).unwrap();
+    let name = format!("../{}", outside.file_name().unwrap().to_string_lossy());
+    match a.call("bookmark_import", &json!({ "doc": doc, "file": name })) {
+        Err(ToolError::Failed(m)) => assert!(m.contains("outside the allowed directory"), "{m}"),
+        other => panic!("expected the root to refuse it, got {other:?}"),
+    }
+    let _ = std::fs::remove_file(&outside);
+    let out = dir.with_extension("out.json");
+    let name = format!("../{}", out.file_name().unwrap().to_string_lossy());
+    match a.call("bookmark_export", &json!({ "doc": doc, "out": name })) {
+        Err(ToolError::Failed(m)) => assert!(m.contains("outside the allowed directory"), "{m}"),
+        other => panic!("expected the root to refuse it, got {other:?}"),
+    }
+    assert!(!out.exists());
+    assert_eq!(ok(&mut a, "bookmark_list", json!({ "doc": doc }))["bookmarks"], json!([]));
+}

crates/automation/tests/it/automation_roots.rs

@@ -145,6 +145,8 @@ fn tools_that_read_a_path_are_held_to_the_read_root() {
     ok(&mut server, "doc_open", json!({"path": s(&base.join("in/a.pdf"))}));
     let (secret, pic, gone) = (s(&base.join("outside/secret.pdf")), s(&base.join("outside/pic.png")), s(&base.join("outside/gone.bin")));
     let out = s(&base.join("out/result.pdf"));
+    std::fs::write(base.join("in/m.prc"), b"PRC model").unwrap();
+    let model = s(&base.join("in/m.prc"));
     for (tool, args) in [
         ("page_insert_file", json!({"doc": 1, "path": secret, "at": 1})),
         ("page_replace", json!({"doc": 1, "pages": [1], "path": secret})),
@@ -153,6 +155,8 @@ fn tools_that_read_a_path_are_held_to_the_read_root() {
         ("doc_create", json!({"from": "images", "paths": [pic]})),
         ("stamp_custom", json!({"doc": 1, "page": 1, "path": secret, "at": [10, 10]})),
         ("stamp_custom", json!({"doc": 1, "page": 1, "path": secret, "rect": [10, 10, 493, 300]})),
+        ("model_add", json!({"doc": 1, "page": 1, "path": secret, "rect": [10, 10, 100, 100]})),
+        ("model_add", json!({"doc": 1, "page": 1, "path": model, "rect": [10, 10, 100, 100], "poster": pic})),
         ("page_add_image", json!({"doc": 1, "page": 1, "path": pic})),
         ("image_edit", json!({"doc": 1, "page": 1, "image": 1, "action": "replace", "path": pic})),
         ("comment_add", json!({"doc": 1, "page": 1, "type": "attachment", "at": [10, 10], "path": secret})),

crates/automation/tests/it/main.rs

@@ -8,6 +8,7 @@ mod batch;
 mod button_caption;
 mod form_bulk;
 mod hostile_args;
+mod model_3d;
 mod model_render;
 mod optimize_content_boundaries;
 mod redact_after_stray_q_form;

crates/automation/tests/it/model_3d.rs

@@ -0,0 +1,120 @@
+//! `model_add` embeds a U3D or PRC model as a 3D annotation (ISO 32000-2 §13.6.2) with a poster,
+//! end to end: the tool, the saved file, undo, and the refusals.
+
+use pdfcraft_automation::{Automation, Content, ToolError};
+use pdfcraft_cos::{Dict, Document, Object, Stream};
+use serde_json::{Value, json};
+
+fn tool(a: &mut Automation, name: &str, args: Value) -> Value {
+    match a.call(name, &args).unwrap().remove(0) {
+        Content::Json(value) => value,
+        other => panic!("expected JSON: {other:?}"),
+    }
+}
+
+fn png(w: u32, h: u32) -> Vec<u8> {
+    let mut out = Vec::new();
+    let mut encoder = png::Encoder::new(&mut out, w, h);
+    encoder.set_color(png::ColorType::Rgb);
+    encoder.set_depth(png::BitDepth::Eight);
+    encoder.write_header().unwrap().write_image_data(&vec![90; (w * h * 3) as usize]).unwrap();
+    out
+}
+
+fn stream(doc: &Document, obj: &Object) -> Stream {
+    match doc.resolve(obj).as_ref() {
+        Object::Stream(s) => s.clone(),
+        other => panic!("expected a stream: {other:?}"),
+    }
+}
+
+/// The 3D annotations on the first page of the saved file.
+fn saved_3d(dir: &std::path::Path) -> (Document, Vec<Dict>) {
+    let doc = Document::open(std::sync::Arc::new(std::fs::read(dir.join("out.pdf")).unwrap())).unwrap();
+    let page = &pdfcraft_model::pages(&doc)[0];
+    let list = page.dict.get(b"Annots").map(|a| doc.resolve(a).as_array().cloned().unwrap()).unwrap_or_default();
+    let found = list.iter().map(|o| doc.resolve(o).as_dict().unwrap().clone()).filter(|d| d.name(b"Subtype") == Some(&b"3D"[..])).collect();
+    (doc, found)
+}
+
+#[test]
+fn model_add_embeds_the_model_with_a_fitted_poster() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut prc = b"PRC".to_vec();
+    prc.extend_from_slice(&[7; 200]);
+    std::fs::write(dir.path().join("bracket.prc"), &prc).unwrap();
+    std::fs::write(dir.path().join("poster.png"), png(80, 40)).unwrap();
+    let mut a = Automation::new().with_root(dir.path()).unwrap();
+    let doc = tool(&mut a, "doc_create", json!({ "from": "blank", "width": 600, "height": 800 }))["doc"].as_u64().unwrap();
+    // A 300 × 300 box from the top-left of the page: user space [100, 400, 400, 700].
+    let call =
+        json!({ "doc": doc, "page": 1, "path": "bracket.prc", "rect": [100, 100, 400, 400], "poster": "poster.png", "activation": "page_open" });
+    tool(&mut a, "model_add", call);
+    tool(&mut a, "doc_save", json!({ "doc": doc, "path": "out.pdf" }));
+
+    let (saved, found) = saved_3d(dir.path());
+    let [annot] = found.as_slice() else { panic!("one 3D annotation: {found:?}") };
+    let rect: Vec<f64> = annot.get(b"Rect").unwrap().as_array().unwrap().iter().filter_map(Object::as_f64).collect();
+    assert_eq!(rect, [100.0, 400.0, 400.0, 700.0]);
+    assert_eq!(annot.get(b"Contents").and_then(Object::as_string).map(|s| s.to_text()).as_deref(), Some("bracket"));
+    let model = stream(&saved, annot.get(b"3DD").unwrap());
+    assert_eq!(model.dict.name(b"Type"), Some(&b"3D"[..]));
+    assert_eq!(model.dict.name(b"Subtype"), Some(&b"PRC"[..]));
+    assert_eq!(model.dict.name(b"Filter"), Some(&b"FlateDecode"[..]));
+    assert_eq!(model.decoded().unwrap().to_vec(), prc, "the model is stored unchanged");
+    let activation = saved.resolve(annot.get(b"3DA").unwrap()).as_dict().unwrap().clone();
+    assert_eq!(activation.name(b"A"), Some(&b"PO"[..]));
+    // The 80 × 40 picture fitted in the 300 × 300 box: 300 × 150, centred top to bottom.
+    let ap = saved.resolve(annot.get(b"AP").unwrap()).as_dict().unwrap().clone();
+    let poster = stream(&saved, ap.get(b"N").unwrap());
+    let content = String::from_utf8(poster.decoded().unwrap().to_vec()).unwrap();
+    assert!(content.contains("300 0 0 150 100 475 cm /Pic Do"), "{content}");
+
+    assert_eq!(tool(&mut a, "edit_undo", json!({ "doc": doc }))["undone"], "Add 3D model");
+    tool(&mut a, "doc_save", json!({ "doc": doc, "path": "out.pdf" }));
+    assert!(saved_3d(dir.path()).1.is_empty(), "undo removes it");
+}
+
+#[test]
+fn model_add_without_a_poster_draws_a_labelled_frame_and_activates_on_click() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut u3d = b"U3D\0".to_vec();
+    u3d.extend_from_slice(&[0; 60]);
+    std::fs::write(dir.path().join("part.u3d"), &u3d).unwrap();
+    let mut a = Automation::new().with_root(dir.path()).unwrap();
+    let doc = tool(&mut a, "doc_create", json!({ "from": "blank", "width": 600, "height": 800 }))["doc"].as_u64().unwrap();
+    tool(&mut a, "model_add", json!({ "doc": doc, "page": 1, "path": "part.u3d", "rect": [50, 50, 250, 200], "name": "Part" }));
+    tool(&mut a, "doc_save", json!({ "doc": doc, "path": "out.pdf" }));
+
+    let (saved, found) = saved_3d(dir.path());
+    let [annot] = found.as_slice() else { panic!("one 3D annotation: {found:?}") };
+    assert_eq!(stream(&saved, annot.get(b"3DD").unwrap()).dict.name(b"Subtype"), Some(&b"U3D"[..]));
+    let activation = saved.resolve(annot.get(b"3DA").unwrap()).as_dict().unwrap().clone();
+    assert_eq!(activation.name(b"A"), Some(&b"XA"[..]), "the standard's default, stated");
+    let ap = saved.resolve(annot.get(b"AP").unwrap()).as_dict().unwrap().clone();
+    let content = String::from_utf8(stream(&saved, ap.get(b"N").unwrap()).decoded().unwrap().to_vec()).unwrap();
+    assert!(content.contains("re S") && content.contains("(3D model) Tj"), "{content}");
+}
+
+#[test]
+fn model_add_refuses_what_is_not_a_model_and_adds_nothing() {
+    let dir = tempfile::tempdir().unwrap();
+    std::fs::write(dir.path().join("notes.txt"), b"PR not a model").unwrap();
+    std::fs::write(dir.path().join("part.prc"), b"PRC....").unwrap();
+    let mut a = Automation::new().with_root(dir.path()).unwrap();
+    let doc = tool(&mut a, "doc_create", json!({ "from": "blank", "width": 600, "height": 800 }))["doc"].as_u64().unwrap();
+    let not_a_model = a.call("model_add", &json!({ "doc": doc, "page": 1, "path": "notes.txt", "rect": [10, 10, 100, 100] }));
+    assert!(matches!(&not_a_model, Err(ToolError::Failed(m)) if m.contains("U3D") && m.contains("PRC")), "{not_a_model:?}");
+    for (args, why) in [
+        (json!({ "rect": [10, 10, 10, 100] }), "zero width"),
+        (json!({ "rect": [0, 0, 20000, 100] }), "wider than a PDF page can be"),
+        (json!({}), "no rect"),
+        (json!({ "rect": [10, 10, 100, 100], "activation": "now" }), "an unknown activation"),
+    ] {
+        let mut call = json!({ "doc": doc, "page": 1, "path": "part.prc" });
+        call.as_object_mut().unwrap().extend(args.as_object().unwrap().clone());
+        assert!(matches!(a.call("model_add", &call), Err(ToolError::InvalidArgs(_))), "{why}");
+    }
+    tool(&mut a, "doc_save", json!({ "doc": doc, "path": "out.pdf" }));
+    assert!(saved_3d(dir.path()).1.is_empty());
+}

crates/cos/src/budget.rs

@@ -25,6 +25,12 @@ pub const MAX_PAGE_DECODED: usize = 256 << 20;
 /// Form XObjects one page's content walk may enter, each entry counted again.
 pub const MAX_PAGE_FORMS: usize = 50_000;
 
+/// The most pixels an image redaction decodes, to clear the ones under a mark or to store again
+/// without the `/JBIG2Globals` it shares with a redacted image (`pdfcraft_redact`). Optimize has
+/// JBIG2 images share a dictionary only within it (`pdfcraft_optimize`), so that redaction can
+/// store each of them again: one it couldn't would refuse the redaction.
+pub const MAX_REDACTED_IMAGE_PIXELS: u64 = 64 << 20;
+
 /// The steps a sample of a JPEG costs: a few bytes can hold a page of one grey, and decoding,
 /// resampling and storing it took about 20 to 45 ns a sample.
 const JPEG_WORK: u64 = 2;

crates/cos/src/document.rs

@@ -19,6 +19,7 @@ mod reader;
 mod state;
 mod xref;
 
+pub(crate) use objects::Held;
 #[cfg(test)]
 pub(crate) use reader::find;
 #[cfg(test)]
@@ -62,6 +63,10 @@ pub struct Document {
     security: Option<Arc<pdfcraft_crypt::SecurityHandler>>,
     /// Object number of the `/Encrypt` dictionary (never encrypted itself).
     encrypt_num: Option<u32>,
+    /// What that dictionary and `/ID` refer to, which the key comes from, and so is as stored.
+    encrypt_members: Arc<HashSet<u32>>,
+    /// Object numbers a scan of the file didn't find: the file doesn't change, so it never will.
+    unfound: Arc<Mutex<HashSet<u32>>>,
     /// Encryption was added, changed or removed since opening: only a full save can apply it.
     encryption_changed: bool,
     /// Set by edits that must not leave earlier revisions in the file (redaction).

crates/cos/src/document/objects.rs

@@ -156,12 +156,16 @@ impl Document {
         self.try_get(r.num).unwrap_or_else(|_| Arc::new(Object::Null))
     }
 
-    /// Follow a reference if `o` is one; otherwise return `o` itself.
+    /// Follow a reference if `o` is one; otherwise return `o` itself. An object can be nothing but
+    /// a reference to another, which is followed too, up to [`MAX_REFERENCE_HOPS`] of them.
     pub fn resolve(&self, o: &Object) -> Arc<Object> {
-        match o {
-            Object::Ref(r) => self.get(*r),
-            other => Arc::new(other.clone()),
+        let Object::Ref(r) = o else { return Arc::new(o.clone()) };
+        let mut held = self.get(*r);
+        for _ in 0..MAX_REFERENCE_HOPS {
+            let Object::Ref(r) = &*held else { break };
+            held = self.get(*r);
         }
+        held
     }
 
     /// `s` with the `/DecodeParms` its filters use made direct, so [`Stream::decoded`] reads them:
@@ -218,7 +222,7 @@ impl Document {
     }
 
     /// `o`, or the object it refers to, without copying either.
-    fn held<'o>(&self, o: &'o Object) -> Held<'o> {
+    pub(crate) fn held<'o>(&self, o: &'o Object) -> Held<'o> {
         match o {
             Object::Ref(_) => Held::Resolved(self.resolve(o)),
             o => Held::Direct(o),
@@ -395,6 +399,7 @@ impl Document {
         // cycles such as `6 0 obj << /Length 6 0 R >>`. Bound the nesting on every path.
         let _guard =
             LoadGuard::enter(num).ok_or_else(|| CosError::Syntax { offset: 0, detail: format!("reference cycle while loading object {num}") })?;
+        let _scope = crate::security::FollowScope::enter();
         let obj = self.load(num, 0)?;
         let obj = Arc::new(obj);
         // The editing cache is bounded like the scan reader's: re-parsing a file-backed view
@@ -562,7 +567,11 @@ impl Document {
         let Object::Stream(s) = &*loaded else { return Err(CosError::MissingObject(num)) };
         let n = s.dict.int(b"N").unwrap_or(0).clamp(0, 1_000_000) as usize;
         let first = usize::try_from(s.dict.int(b"First").unwrap_or(0).max(0)).ok();
-        let data = s.decoded_within(self.stream_limit)?;
+        // Its parameters can be given by reference, and can sit in another object stream. A scan of
+        // the file's object streams comes here without a read around it.
+        let _scope = crate::security::FollowScope::enter();
+        let readable = crate::security::following(Cow::Borrowed(s), || self.with_direct_parms(s));
+        let data = readable.decoded_within(self.stream_limit)?;
         let mut lx = Lexer::new(&data, 0);
         let mut index = Vec::with_capacity(n);
         for _ in 0..n {
@@ -577,8 +586,14 @@ impl Document {
         Ok(stm)
     }
 
-    /// Last-resort lookup: scan the file for `num G obj`.
+    /// Last-resort lookup: scan the file for `num G obj`. What isn't there is remembered: each miss
+    /// reads the whole file, and a file can refer to such an object from everywhere.
     fn scan_for(&self, num: u32) -> Option<(ObjRef, Object)> {
+        if self.unfound.lock().is_ok_and(|unfound| unfound.contains(&num)) {
+            return None;
+        }
+        #[cfg(test)]
+        super::tests::FILE_SCANS.with(|scans| scans.set(scans.get() + 1));
         let needle = format!("{num} ");
         let data = &self.data;
         let mut found = None;
@@ -594,6 +609,11 @@ impl Document {
                 found = Some((id, o)); // keep the last (newest) definition
             }
         }
+        if found.is_none()
+            && let Ok(mut unfound) = self.unfound.lock()
+        {
+            unfound.insert(num);
+        }
         found
     }
 
@@ -659,8 +679,9 @@ impl Document {
     ///
     /// Used when the working snapshot was restored from an earlier revision and the next
     /// incremental save must still append to this file (the last saved revision). Objects
-    /// that already match are left untouched. Reads go through private readers so neither
-    /// document's editing cache is filled.
+    /// that already match are left untouched, except members of an object stream of this file
+    /// whose stream number `current` frees or reuses: those are written again on their own.
+    /// Reads go through private readers so neither document's editing cache is filled.
     pub fn overlay_changes_from(&mut self, current: &Document) -> Result<(), CosError> {
         let saved_nums = self.object_numbers();
         let current_nums = current.object_numbers();
@@ -684,6 +705,22 @@ impl Document {
                 }
             }
         }
+        // An object stream of this file that is freed or replaced takes its members with it, so
+        // a member that is otherwise unchanged is written again on its own.
+        let gone = |n: u32| freed.binary_search(&n).is_ok() || changed.binary_search(&n).is_ok();
+        let orphaned: Vec<u32> = current_nums
+            .iter()
+            .copied()
+            .filter(|&num| changed.binary_search(&num).is_err())
+            .filter(|&num| {
+                let packed_in = match self.xref_entry(num) {
+                    Some(XrefEntry::InStream { stream, .. }) => Some(stream),
+                    _ => None,
+                };
+                packed_in.is_some_and(gone)
+            })
+            .collect();
+        changed.extend(orphaned);
         for num in freed {
             let generation = self.generation(num);
             self.free(ObjRef::new(num, generation));
@@ -786,9 +823,13 @@ const DECODE_PARMS_KEYS: [&[u8]; 13] = [
     b"ColorTransform",
 ];
 
+/// How many references in a row [`Document::resolve`] follows: enough for any file, and it ends a
+/// cycle of them.
+const MAX_REFERENCE_HOPS: usize = 32;
+
 /// An object read in place, or the object a reference names as the document holds it: either way
 /// nothing is copied ([`Document::held`]).
-enum Held<'o> {
+pub(crate) enum Held<'o> {
     Direct(&'o Object),
     Resolved(Arc<Object>),
 }

crates/cos/src/document/open.rs

@@ -1,7 +1,11 @@
 use super::reader::find;
 use super::state::Credentials;
 use super::xref::XrefIndex;
-use super::{Arc, BTreeMap, CosError, Dict, Document, ObjRef, Object};
+use super::{Arc, BTreeMap, CosError, Dict, Document, HashSet, ObjRef, Object};
+
+/// More objects than `/Encrypt` and `/ID` refer to in any file, so that one which refers to the page
+/// tree, say, doesn't have a whole document read to open it.
+const MAX_ENCRYPT_MEMBERS: usize = 64;
 
 impl Document {
     /// A new document with an empty page tree (for split / extract / combine). It has no
@@ -27,6 +31,8 @@ impl Document {
             version: "1.7".into(),
             security: None,
             encrypt_num: None,
+            encrypt_members: Arc::default(),
+            unfound: Arc::default(),
             encryption_changed: false,
             full_save: false,
             out_security: None,
@@ -111,6 +117,8 @@ impl Document {
             version,
             security: None,
             encrypt_num: None,
+            encrypt_members: Arc::default(),
+            unfound: Arc::default(),
             encryption_changed: false,
             full_save: false,
             out_security: None,
@@ -185,6 +193,8 @@ impl Document {
         };
         let params = crate::security::encrypt_dict(self, &dict);
         let id0 = self.first_id();
+        // Read here, while nothing is decrypted yet.
+        let members = self.encryption_members(enc);
         let handler = match credentials {
             Credentials::Password(password) => Arc::new(pdfcraft_crypt::SecurityHandler::open(params, &id0, *password).map_err(|e| match e {
                 pdfcraft_crypt::CryptError::WrongPassword if password.is_none() => CosError::NeedsPassword,
@@ -197,6 +207,7 @@ impl Document {
         };
         self.security = Some(handler);
         self.encrypt_num = num;
+        self.encrypt_members = Arc::new(members);
         // Objects read while locating the catalog were read before decryption was possible.
         self.cache = Arc::default();
         self.objstms = Arc::default();
@@ -205,10 +216,42 @@ impl Document {
 
     /// The first file identifier, part of the encryption key (empty when there is none).
     fn first_id(&self) -> Vec<u8> {
-        match self.trailer.get(b"ID") {
-            Some(Object::Array(a)) => a.first().and_then(|s| s.as_string()).map(|s| s.bytes.clone()).unwrap_or_default(),
-            _ => Vec::new(),
+        let id = self.trailer.get(b"ID").map(|id| self.resolve(id));
+        let first = id.as_deref().and_then(Object::as_array).and_then(|a| a.first()).map(|s| self.resolve(s));
+        first.as_deref().and_then(Object::as_string).map(|s| s.bytes.clone()).unwrap_or_default()
+    }
+
+    /// The objects `/Encrypt`, given as `enc`, and `/ID` refer to, the ones they refer to, and so
+    /// on, up to [`MAX_ENCRYPT_MEMBERS`]. Their strings aren't encrypted (ISO 32000-2 §7.6.2): the
+    /// key is made from them, so they have to read as stored, and stay so. A number with no object
+    /// behind it, and a stream, which those dictionaries never hold, isn't one: an object added
+    /// under that number later, or a page's content a hostile `/Encrypt` names, is encrypted.
+    fn encryption_members(&self, enc: &Object) -> HashSet<u32> {
+        let mut pending = Vec::new();
+        crate::writer::collect_refs(enc, &mut |r| pending.push(r));
+        if let Some(id) = self.trailer.get(b"ID") {
+            crate::writer::collect_refs(id, &mut |r| pending.push(r));
         }
+        let mut members = HashSet::new();
+        while let Some(r) = pending.pop() {
+            if members.len() >= MAX_ENCRYPT_MEMBERS || members.contains(&r.num) {
+                continue;
+            }
+            let held = self.get(r);
+            if matches!(&*held, Object::Null | Object::Stream(_)) {
+                continue;
+            }
+            members.insert(r.num);
+            crate::writer::collect_refs(&held, &mut |x| pending.push(x));
+        }
+        members
+    }
+
+    /// Whether object `num` is written as it is held, being one of [`Document::encryption_members`],
+    /// unedited, and the save writing the same `/Encrypt`. What was edited or added is encrypted
+    /// whatever its number.
+    pub(crate) fn stored_as_is(&self, num: u32) -> bool {
+        !self.encryption_changed && !self.is_edited(num) && self.encrypt_members.contains(&num)
     }
 
     /// Lift the restrictions of a document opened with its user password by entering the
@@ -270,8 +313,9 @@ impl Document {
     /// always a full rewrite. Returns the handler (authenticated as owner).
     pub fn set_encryption(&mut self, params: &pdfcraft_crypt::NewEncryption) -> Result<(), CosError> {
         // The file identifier is part of the key; make sure it exists and keep it.
-        let id0 = match self.trailer.get(b"ID") {
-            Some(Object::Array(a)) if a.len() == 2 => a[0].as_string().map(|s| s.bytes.clone()).unwrap_or_default(),
+        let id = self.trailer.get(b"ID").map(|id| self.resolve(id));
+        let id0 = match id.as_deref() {
+            Some(Object::Array(a)) if a.len() == 2 => self.first_id(),
             _ => {
                 let id = pdfcraft_crypt::file_id(&params.seed);
                 let s = Object::String(crate::PdfString { bytes: id.clone(), hex: true });
@@ -338,7 +382,9 @@ impl Document {
     /// Decrypt a freshly parsed indirect object if the document is encrypted.
     pub(super) fn decrypted(&self, id: ObjRef, o: Object) -> Object {
         match &self.security {
-            Some(h) if Some(id.num) != self.encrypt_num => crate::security::transform(h, &o, id.num, id.generation, crate::security::Pass::Decrypt),
+            Some(h) if Some(id.num) != self.encrypt_num && !self.encrypt_members.contains(&id.num) => {
+                crate::security::transform(self, h, &o, id.num, id.generation, crate::security::Pass::Decrypt)
+            }
             _ => o,
         }
     }

crates/cos/src/document/tests.rs

@@ -1,5 +1,147 @@
 use super::*;
 
+std::thread_local! {
+    /// How many times `Document::scan_for` read the file on this thread.
+    pub(super) static FILE_SCANS: std::cell::Cell<usize> = const { std::cell::Cell::new(0) };
+}
+
+/// A scan that doesn't find an object isn't made again: each reads the whole file, and a file can
+/// refer to such an object from every object it has.
+#[test]
+fn what_a_scan_of_the_file_did_not_find_is_remembered() {
+    let body = b"%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n2 0 obj << /Type /Pages /Kids [] /Count 0 >> endobj\n";
+    let mut out = body.to_vec();
+    let xref = out.len();
+    out.extend_from_slice(b"xref\n0 4\n0000000000 65535 f \n");
+    out.extend_from_slice(format!("{:010} 00000 n \n", 9).as_bytes());
+    out.extend_from_slice(format!("{:010} 00000 n \n", body.iter().position(|b| *b == b'\n').unwrap() + 49).as_bytes());
+    out.extend_from_slice(b"0000000001 00000 n \n");
+    out.extend_from_slice(format!("trailer << /Size 4 /Root 1 0 R >>\nstartxref\n{xref}\n%%EOF\n").as_bytes());
+    let doc = Document::open(Arc::new(out)).unwrap();
+    FILE_SCANS.with(|scans| scans.set(0));
+    for _ in 0..5 {
+        assert!(doc.try_get(3).is_err());
+    }
+    assert_eq!(FILE_SCANS.with(std::cell::Cell::get), 1);
+    let clone = doc.clone();
+    assert!(clone.try_get(3).is_err());
+    assert_eq!(FILE_SCANS.with(std::cell::Cell::get), 1, "a clone has the same file");
+}
+
+/// An object can be nothing but a reference to another. A chain of them is followed, and one that
+/// goes round ends in what isn't a dictionary or a name, without hanging.
+#[test]
+fn references_to_references_are_followed() {
+    let mut doc = Document::new_empty();
+    let name = doc.add(Object::name("Target"));
+    let one = doc.add(Object::Ref(name));
+    let two = doc.add(Object::Ref(one));
+    assert_eq!(doc.resolve(&Object::Ref(two)).as_name(), Some(b"Target".as_slice()));
+    let a = doc.add(Object::Null);
+    let b = doc.add(Object::Ref(a));
+    doc.set(a, Object::Ref(b));
+    assert_eq!(doc.resolve(&Object::Ref(a)).as_name(), None);
+}
+
+/// An object stream's `/DecodeParms` can be given by reference: without them a predictor isn't
+/// undone, so its members were lost.
+#[test]
+fn an_object_stream_with_parameters_by_reference_is_read() {
+    let members = b"3 0 << /Hidden (yes) >>";
+    // PNG Sub, one row.
+    let mut rows = vec![1u8];
+    let mut before = 0u8;
+    for b in members {
+        rows.push(b.wrapping_sub(before));
+        before = *b;
+    }
+    let coded = pdfcraft_filters::encode_flate(&rows);
+    let mut out = b"%PDF-1.5\n".to_vec();
+    let mut offs = [0usize; 7];
+    let mut obj = |out: &mut Vec<u8>, n: usize, body: &[u8]| {
+        offs[n] = out.len();
+        out.extend_from_slice(format!("{n} 0 obj\n").as_bytes());
+        out.extend_from_slice(body);
+        out.extend_from_slice(b"\nendobj\n");
+    };
+    obj(&mut out, 1, b"<< /Type /Catalog /Pages 2 0 R >>");
+    obj(&mut out, 2, b"<< /Type /Pages /Kids [] /Count 0 /Extra 3 0 R >>");
+    let mut stm = format!("<< /Type /ObjStm /N 1 /First 4 /Filter /FlateDecode /DecodeParms 6 0 R /Length {} >>\nstream\n", coded.len()).into_bytes();
+    stm.extend_from_slice(&coded);
+    stm.extend_from_slice(b"\nendstream");
+    obj(&mut out, 4, &stm);
+    let data = [2u8, 0, 4, 0];
+    let mut xs = format!("<< /Type /XRef /Size 7 /W [1 2 1] /Index [3 1] /Length {} >>\nstream\n", data.len()).into_bytes();
+    xs.extend_from_slice(&data);
+    xs.extend_from_slice(b"\nendstream");
+    obj(&mut out, 5, &xs);
+    obj(&mut out, 6, format!("<< /Predictor 11 /Columns {} >>", members.len()).as_bytes());
+    let table = out.len();
+    out.extend_from_slice(b"xref\n0 7\n0000000000 65535 f \n");
+    for (n, off) in offs.iter().enumerate().skip(1) {
+        let line = if n == 3 { "0000000000 65535 f \n".to_string() } else { format!("{off:010} 00000 n \n") };
+        out.extend_from_slice(line.as_bytes());
+    }
+    out.extend_from_slice(format!("trailer << /Size 7 /Root 1 0 R /XRefStm {} >>\nstartxref\n{table}\n%%EOF\n", offs[5]).as_bytes());
+    let doc = Document::open(Arc::new(out)).unwrap();
+    let hidden = doc.get(ObjRef::new(3, 0));
+    assert_eq!(hidden.as_dict().and_then(|d| d.get(b"Hidden")).and_then(Object::as_string).map(|s| s.bytes.clone()), Some(b"yes".to_vec()));
+}
+
+/// Each entry of an `/Encrypt` dictionary, and of a crypt filter in it, reads the same by reference.
+/// Read as absent, `/StmF` or `/CFM` was `/Identity`, so a whole file's streams stayed ciphertext.
+#[test]
+fn encrypt_dictionary_entries_read_the_same_by_reference() {
+    let string = |s: &str| Object::String(crate::PdfString::text(s));
+    let mut filter = Dict::new();
+    filter.set(b"CFM".to_vec(), Object::name("AESV2"));
+    filter.set(b"Length".to_vec(), Object::Int(5));
+    let cf = |filter: Dict| {
+        let mut cf = Dict::new();
+        cf.set(b"StdCF".to_vec(), Object::Dict(filter));
+        cf.set(b"Other".to_vec(), Object::Dict(Dict::new()));
+        Object::Dict(cf)
+    };
+    let mut d = Dict::new();
+    let entries = [
+        ("Filter", Object::name("Standard")),
+        ("V", Object::Int(4)),
+        ("R", Object::Int(4)),
+        ("Length", Object::Int(128)),
+        ("P", Object::Int(-44)),
+        ("O", string("owner")),
+        ("U", string("user")),
+        ("EncryptMetadata", Object::Bool(false)),
+        ("CF", cf(filter.clone())),
+        ("StmF", Object::name("StdCF")),
+        ("StrF", Object::name("Other")),
+        ("EFF", Object::name("StdCF")),
+    ];
+    for (key, value) in &entries {
+        d.set(key.as_bytes().to_vec(), value.clone());
+    }
+    let mut doc = Document::new_empty();
+    let direct = crate::security::encrypt_dict(&doc, &d);
+    assert_eq!((direct.stm_f.as_slice(), direct.str_f.as_slice(), direct.ef_f.as_slice()), (&b"StdCF"[..], &b"Other"[..], &b"StdCF"[..]));
+    assert_eq!(direct.length_bits, 40, "the filter's own length, in bytes");
+    assert!(!direct.encrypt_metadata);
+    assert_eq!(direct.crypt_filters.iter().filter(|(_, m)| *m == pdfcraft_crypt::Method::Aes128).count(), 1);
+    for (key, value) in &entries {
+        let mut one = d.clone();
+        let r = doc.add(value.clone());
+        one.set(key.as_bytes().to_vec(), Object::Ref(r));
+        assert_eq!(crate::security::encrypt_dict(&doc, &one), direct, "/{key}");
+    }
+    for key in ["CFM", "Length"] {
+        let mut by_reference = filter.clone();
+        let r = doc.add(filter.get(key.as_bytes()).unwrap().clone());
+        by_reference.set(key.as_bytes().to_vec(), Object::Ref(r));
+        let mut one = d.clone();
+        one.set(b"CF".to_vec(), cf(by_reference));
+        assert_eq!(crate::security::encrypt_dict(&doc, &one), direct, "/{key} in the filter");
+    }
+}
+
 /// /DecodeParms given by reference, whole, as array entries or as the numbers inside, are read
 /// once made direct: here a Flate predictor, which the stream alone doesn't see. Only the entries the filters use are
 /// resolved, and nothing is for a chain longer than a decoder takes.
@@ -1704,6 +1846,32 @@ fn a_stream_whose_length_is_itself_and_never_ends_loads_quickly() {
     rx.recv_timeout(std::time::Duration::from_secs(20)).expect("loading must not retry exponentially");
 }
 
+#[test]
+fn a_restored_revision_keeps_what_the_saved_file_held_in_object_streams() {
+    // The earlier revision: an empty document read back from a file whose catalog and pages
+    // sit in an object stream.
+    let earlier = Document::open(Arc::new(crate::write_full(&Document::new_empty(), &crate::SaveOptions::default()).unwrap())).unwrap();
+    // The saved revision adds an object the catalog links to, so a full save numbers its objects
+    // anew; an undo then returns to the earlier graph.
+    let mut later = earlier.clone();
+    let extra = later.add(Object::Int(7));
+    let root = later.root().unwrap();
+    later.update_dict(root, |c| c.set(b"Extra".to_vec(), Object::Ref(extra))).unwrap();
+    let saved = crate::write_full(&later, &crate::SaveOptions::default()).unwrap();
+    let mut base = Document::open(Arc::new(saved)).unwrap();
+    assert!(
+        base.object_numbers().iter().any(|&n| matches!(base.xref_entry(n), Some(XrefEntry::InStream { .. }))),
+        "the saved file holds objects in a stream"
+    );
+    base.overlay_changes_from(&earlier).unwrap();
+    let file = crate::write_incremental(&base, &crate::SaveOptions::default()).unwrap();
+    let reread = Document::open(Arc::new(file)).unwrap();
+    let catalog = reread.get(reread.root().unwrap()).as_dict().unwrap().clone();
+    assert!(catalog.get(b"Extra").is_none(), "the restored catalog");
+    let pages = reread.resolve(catalog.get(b"Pages").unwrap());
+    assert_eq!(pages.as_dict().and_then(|d| d.name(b"Type")), Some(&b"Pages"[..]), "the pages survive: {pages:?}");
+}
+
 /// The cache keeps the sum of what its objects hold as they come and go, so neither reader has
 /// to measure the cache again on every read (#5873).
 #[test]

crates/cos/src/lib.rs

@@ -22,7 +22,7 @@ mod parser;
 mod security;
 mod writer;
 
-pub use budget::{DecodeBudget, ImageBudget, MAX_PAGE_DECODED, MAX_PAGE_FORMS};
+pub use budget::{DecodeBudget, ImageBudget, MAX_PAGE_DECODED, MAX_PAGE_FORMS, MAX_REDACTED_IMAGE_PIXELS};
 pub use bytes::Bytes;
 pub use document::{Document, ReadState, Revision, SourceIdentity, XrefEntry};
 pub use object::{Dict, MAX_DECODED, MAX_JBIG2_GLOBALS, Name, ObjRef, Object, PdfString, Stream};

crates/cos/src/security.rs

@@ -7,10 +7,69 @@
 //! false. Streams naming a crypt filter (`/Crypt` in `/Filter`) use that filter; embedded files
 //! use `/EFF`.
 
-use pdfcraft_crypt::{EncryptDict, Method, SecurityHandler, StreamKind};
+use std::cell::Cell;
 
+use pdfcraft_crypt::{EncryptDict, Method, SecurityHandler, StreamKind};
+use pdfcraft_filters::MAX_CHAIN;
+
+use crate::document::Held;
 use crate::{Dict, Document, Object, PdfString, Stream};
 
+/// How many references one read or write of an object may follow, with all that it loads on the
+/// way. How an object is treated can be given by reference, and what that loads can do the same: a
+/// file could make one read a tree of them, each object read again once the cache has let it go.
+/// An object takes a few of these, and two dozen if every part of it is given by reference; past
+/// this they read as absent. The parameters of an object stream, read together, count as one.
+const MAX_FOLLOWED: u32 = 32;
+
+std::thread_local! {
+    /// How many [`FollowScope`]s this thread is inside.
+    static SCOPES: Cell<u32> = const { Cell::new(0) };
+    /// The references followed in the outermost of them.
+    static FOLLOWED: Cell<u32> = const { Cell::new(0) };
+    /// The references refused in the outermost of them, past [`MAX_FOLLOWED`].
+    static REFUSED: Cell<u32> = const { Cell::new(0) };
+}
+
+/// One read or write of an object, with everything it loads on the way: what [`MAX_FOLLOWED`] counts.
+pub(crate) struct FollowScope;
+
+impl FollowScope {
+    pub(crate) fn enter() -> Self {
+        if SCOPES.replace(SCOPES.get().saturating_add(1)) == 0 {
+            FOLLOWED.set(0);
+            REFUSED.set(0);
+        }
+        FollowScope
+    }
+}
+
+impl Drop for FollowScope {
+    fn drop(&mut self) {
+        SCOPES.set(SCOPES.get().saturating_sub(1));
+    }
+}
+
+/// What `f` gives, counted against [`MAX_FOLLOWED`], or `spent` past it. Called inside a
+/// [`FollowScope`], which is what starts the count again.
+pub(crate) fn following<T>(spent: T, f: impl FnOnce() -> T) -> T {
+    if FOLLOWED.get() >= MAX_FOLLOWED {
+        REFUSED.set(REFUSED.get().saturating_add(1));
+        return spent;
+    }
+    FOLLOWED.set(FOLLOWED.get() + 1);
+    f()
+}
+
+/// `o`, or the object it refers to, for what decides how a stream or dictionary is treated. Past
+/// [`MAX_FOLLOWED`] a reference reads as absent.
+fn followed<'o>(doc: &Document, o: &'o Object) -> Held<'o> {
+    match o {
+        Object::Ref(_) => following(Held::Direct(&Object::Null), || doc.held(o)),
+        o => Held::Direct(o),
+    }
+}
+
 fn bytes_of(doc: &Document, d: &Dict, key: &[u8]) -> Vec<u8> {
     d.get(key).map(|v| doc.resolve(v)).and_then(|v| v.as_string().map(|s| s.bytes.clone())).unwrap_or_default()
 }
@@ -18,12 +77,12 @@ fn bytes_of(doc: &Document, d: &Dict, key: &[u8]) -> Vec<u8> {
 /// Read the handler parameters from an `/Encrypt` dictionary.
 pub(crate) fn encrypt_dict(doc: &Document, d: &Dict) -> EncryptDict {
     let int = |k: &[u8], default: i64| d.get(k).map(|v| doc.resolve(v)).and_then(|v| v.as_int()).unwrap_or(default);
-    let name = |k: &[u8]| d.get(k).and_then(|v| v.as_name()).map(|n| n.to_vec()).unwrap_or_else(|| b"Identity".to_vec());
+    let name = |d: &Dict, k: &[u8]| d.get(k).and_then(|v| doc.resolve(v).as_name().map(<[u8]>::to_vec));
     let mut crypt_filters = Vec::new();
     if let Some(cf) = d.get(b"CF").map(|c| doc.resolve(c)).and_then(|c| c.as_dict().cloned()) {
         for (k, v) in cf.iter() {
             let Some(f) = doc.resolve(v).as_dict().cloned() else { continue };
-            let method = match f.name(b"CFM") {
+            let method = match name(&f, b"CFM").as_deref() {
                 Some(b"V2") => Method::Rc4,
                 Some(b"AESV2") => Method::Aes128,
                 Some(b"AESV3") => Method::Aes256,
@@ -40,7 +99,8 @@ pub(crate) fn encrypt_dict(doc: &Document, d: &Dict) -> EncryptDict {
         .get(b"CF")
         .map(|c| doc.resolve(c))
         .and_then(|c| c.as_dict().and_then(|c| c.get(b"StdCF").map(|f| doc.resolve(f))))
-        .and_then(|f| f.as_dict().and_then(|f| f.int(b"Length")))
+        .and_then(|f| f.as_dict().and_then(|f| f.get(b"Length").map(|n| doc.resolve(n))))
+        .and_then(|n| n.as_int())
         .filter(|n| *n > 0);
     let length_bits = match (v, cf_len) {
         (5.., _) => 256,
@@ -50,7 +110,7 @@ pub(crate) fn encrypt_dict(doc: &Document, d: &Dict) -> EncryptDict {
         _ => int(b"Length", 40),
     };
     EncryptDict {
-        filter: d.name(b"Filter").map(|n| n.to_vec()).unwrap_or_default(),
+        filter: name(d, b"Filter").unwrap_or_default(),
         v,
         r: int(b"R", 0),
         length_bits,
@@ -60,28 +120,46 @@ pub(crate) fn encrypt_dict(doc: &Document, d: &Dict) -> EncryptDict {
         ue: bytes_of(doc, d, b"UE"),
         perms: bytes_of(doc, d, b"Perms"),
         p: int(b"P", -1) as i32,
-        encrypt_metadata: !matches!(d.get(b"EncryptMetadata"), Some(Object::Bool(false))),
+        encrypt_metadata: !matches!(d.get(b"EncryptMetadata").map(|v| doc.resolve(v)).as_deref(), Some(Object::Bool(false))),
         crypt_filters,
-        stm_f: name(b"StmF"),
-        str_f: name(b"StrF"),
-        ef_f: d.get(b"EFF").and_then(|v| v.as_name()).map(|n| n.to_vec()).unwrap_or_default(),
+        stm_f: name(d, b"StmF").unwrap_or_else(|| b"Identity".to_vec()),
+        str_f: name(d, b"StrF").unwrap_or_else(|| b"Identity".to_vec()),
+        ef_f: name(d, b"EFF").unwrap_or_default(),
     }
 }
 
-/// The crypt filter a stream names in its `/Filter` chain (`/Crypt` + `/DecodeParms /Name`).
-fn named_crypt_filter(dict: &Dict) -> Option<Vec<u8>> {
-    let names: Vec<&[u8]> = match dict.get(b"Filter") {
-        Some(Object::Name(n)) => vec![n],
-        Some(Object::Array(a)) => a.iter().filter_map(Object::as_name).collect(),
+/// Whether `f`, an entry of a `/Filter` chain or its only filter, is `/Crypt`.
+fn is_crypt(doc: &Document, f: &Object) -> bool {
+    followed(doc, f).as_name() == Some(b"Crypt")
+}
+
+/// The crypt filter a stream names in its `/Filter` chain (`/Crypt` + `/DecodeParms /Name`), each
+/// given directly or by reference, in an array or not. A chain longer than any decoder takes names
+/// none: nothing can read that stream anyway, and every stream of a file can share one long array.
+/// A `/Name` that reads as absent means `/Identity`, unless a reference on the way to it was refused
+/// (see [`MAX_FOLLOWED`]): that says nothing about the stream, so it names none, and the document's
+/// own filter is used.
+fn named_crypt_filter(doc: &Document, dict: &Dict) -> Option<Vec<u8>> {
+    let refused = REFUSED.get();
+    let filter = followed(doc, dict.get(b"Filter")?);
+    let i = match &*filter {
+        Object::Array(a) if a.len() <= MAX_CHAIN + 1 => a.iter().position(|f| is_crypt(doc, f))?,
+        f if is_crypt(doc, f) => 0,
         _ => return None,
     };
-    let i = names.iter().position(|n| *n == b"Crypt")?;
-    let parms = match dict.get(b"DecodeParms") {
-        Some(Object::Dict(d)) if i == 0 => Some(d.clone()),
-        Some(Object::Array(a)) => a.get(i).and_then(|p| p.as_dict().cloned()),
+    let parms = dict.get(b"DecodeParms").map(|p| followed(doc, p));
+    let entry = match parms.as_deref() {
+        Some(Object::Array(a)) => a.get(i).map(|p| followed(doc, p)),
+        Some(p) if i == 0 => Some(Held::Direct(p)),
         _ => None,
     };
-    Some(parms.and_then(|p| p.name(b"Name").map(|n| n.to_vec())).unwrap_or_else(|| b"Identity".to_vec()))
+    let name = entry.as_deref().and_then(Object::as_dict).and_then(|p| p.get(b"Name")).map(|n| followed(doc, n));
+    match name.as_deref().and_then(Object::as_name) {
+        Some(name) => Some(name.to_vec()),
+        // /Identity here would read ciphertext as data, and write the stream in the clear.
+        None if REFUSED.get() > refused => None,
+        None => Some(b"Identity".to_vec()),
+    }
 }
 
 /// A signature dictionary (field signature, document timestamp or usage-rights signature),
@@ -91,42 +169,67 @@ fn named_crypt_filter(dict: &Dict) -> Option<Vec<u8>> {
 /// `/Contents` alongside an array `/ByteRange` (`/Type` is optional). A signature dictionary
 /// has no `/Subtype`; a dictionary with one (an annotation, whose `/Contents` is the comment
 /// text) or with another `/Type` is never exempt, whatever else it carries.
-fn is_signature_dict(d: &Dict) -> bool {
-    if d.get(b"Subtype").is_some() {
+/// With `doc` its entries are read through references; a dictionary nested in another object
+/// has none (see [`transform`]).
+fn is_signature_dict(doc: Option<&Document>, d: &Dict) -> bool {
+    // All this decides is what happens to such a /Contents.
+    if !matches!(d.get(b"Contents"), Some(Object::String(_))) {
         return false;
     }
-    match d.get(b"Type") {
-        Some(_) => matches!(d.name(b"Type"), Some(b"Sig" | b"DocTimeStamp")),
-        None => matches!(d.get(b"Contents"), Some(Object::String(_))) && matches!(d.get(b"ByteRange"), Some(Object::Array(_))),
+    // A null entry, or one that refers to nothing, is an absent one (ISO 32000-2 §7.3.7, §7.3.10).
+    let entry = |key: &[u8]| {
+        let value = d.get(key)?;
+        let held = doc.map_or(Held::Direct(value), |doc| followed(doc, value));
+        (!matches!(*held, Object::Null)).then_some(held)
+    };
+    if entry(b"Subtype").is_some() {
+        return false;
+    }
+    match entry(b"Type") {
+        Some(t) => matches!(t.as_name(), Some(b"Sig" | b"DocTimeStamp")),
+        None => matches!(entry(b"ByteRange").as_deref(), Some(Object::Array(_))),
     }
 }
 
-/// Remove the `/Crypt` entry from a stream's filter chain, with its decode parameters.
-fn drop_crypt_filter(dict: &mut Dict) {
-    let i = match dict.get(b"Filter") {
-        Some(Object::Array(a)) => a.iter().position(|n| n.as_name() == Some(b"Crypt")),
-        Some(Object::Name(n)) if n.as_slice() == b"Crypt" => Some(0),
-        _ => None,
+/// Longer than any filter's name. A name can be of any length, and a chain every stream shares can
+/// hold a long one.
+const MAX_FILTER_NAME: usize = 127;
+
+/// The dictionary of `source` without the `/Crypt` entries of its filter chain and their decode
+/// parameters. The two come out direct when given by reference, which every stream of a file can
+/// share, so of what was shared only small values are copied: filter names, and the parameters
+/// decoders read ([`Document::with_direct_parms`]). The chain is short, as [`named_crypt_filter`]
+/// found a filter in it.
+fn drop_crypt_filter(doc: &Document, source: &Stream) -> Dict {
+    let entry = |f: &Object| match f {
+        f if is_crypt(doc, f) => Object::name("Crypt"),
+        Object::Name(n) if n.len() <= MAX_FILTER_NAME => f.clone(),
+        Object::Ref(_) => f.clone(),
+        _ => Object::Null,
     };
-    let Some(i) = i else { return };
-    let mut filters = match dict.get(b"Filter") {
-        Some(Object::Array(a)) => a.clone(),
-        _ => Vec::new(),
+    let filter = source.dict.get(b"Filter").map(|f| followed(doc, f));
+    let chain: Vec<Object> = match filter.as_deref() {
+        Some(Object::Array(a)) => a.iter().map(entry).collect(),
+        Some(f) => vec![entry(f)],
+        None => Vec::new(),
     };
-    if i < filters.len() {
-        filters.remove(i);
-    }
+    let crypt: Vec<bool> = chain.iter().map(|f| f.as_name() == Some(b"Crypt")).collect();
+    let mut chained = Stream::from_raw(source.dict.clone(), Vec::new());
+    chained.dict.set(b"Filter".to_vec(), Object::Array(chain.clone()));
     // A lone parameter dictionary belongs to the first filter (as `named_crypt_filter` reads it).
-    match dict.get(b"DecodeParms").cloned() {
-        Some(Object::Array(mut parms)) if i < parms.len() => {
-            parms.remove(i);
-            dict.set(b"DecodeParms".to_vec(), Object::Array(parms));
-        }
-        Some(Object::Dict(_)) if i == 0 => {
+    let parms = match doc.with_direct_parms(&chained).dict.get(b"DecodeParms") {
+        Some(Object::Array(p)) => Some(Object::Array(p.iter().zip(&crypt).filter(|(_, c)| !**c).map(|(p, _)| p.clone()).collect())),
+        Some(Object::Dict(_)) if crypt.first() == Some(&true) => None,
+        _ => source.dict.get(b"DecodeParms").cloned(),
+    };
+    let mut dict = source.dict.clone();
+    match parms {
+        Some(p) => dict.set(b"DecodeParms".to_vec(), p),
+        None => {
             dict.remove(b"DecodeParms");
         }
-        _ => {}
     }
+    let filters: Vec<Object> = chain.into_iter().zip(&crypt).filter(|(_, c)| !**c).map(|(f, _)| f).collect();
     if filters.is_empty() {
         dict.remove(b"Filter");
         if matches!(dict.get(b"DecodeParms"), Some(Object::Array(p)) if p.is_empty()) {
@@ -135,6 +238,7 @@ fn drop_crypt_filter(dict: &mut Dict) {
     } else {
         dict.set(b"Filter".to_vec(), Object::Array(filters));
     }
+    dict
 }
 
 /// What [`transform`] does to an object.
@@ -152,51 +256,81 @@ pub(crate) enum Pass {
 
 /// Decrypt or encrypt every string and stream in an indirect object, except a signature
 /// dictionary's `/Contents` (see [`is_signature_dict`]).
-pub(crate) fn transform(h: &SecurityHandler, o: &Object, num: u32, generation: u16, pass: Pass) -> Object {
+///
+/// `o` is as `doc` holds it: what a stream's dictionary gives by reference is read from `doc`, so
+/// its references have to be the document's, not a save's renumbered ones.
+pub(crate) fn transform(doc: &Document, h: &SecurityHandler, o: &Object, num: u32, generation: u16, pass: Pass) -> Object {
+    let _scope = FollowScope::enter();
     let decrypt = pass == Pass::Decrypt;
     let strings = |s: &PdfString| {
         let bytes = if decrypt { h.decrypt_string(num, generation, &s.bytes) } else { h.encrypt_string(num, generation, &s.bytes) };
         PdfString { bytes, hex: s.hex || !decrypt }
     };
-    walk(o, &strings, h, num, generation, pass)
+    // References are followed here only, for the object itself, never for what is nested in it.
+    // `walk` goes deep, and a load from down there adds that depth again for each object loaded,
+    // which overflowed the stack on a 10 KB file. A stream can't be nested, and a dictionary that
+    // is reads as it says directly.
+    match o {
+        Object::Stream(s) => stream(doc, s, &strings, h, num, generation, pass),
+        Object::Dict(d) if is_signature_dict(Some(doc), d) => signature_dict(d, &strings),
+        o => walk(o, &strings),
+    }
 }
 
-fn walk(o: &Object, strings: &dyn Fn(&PdfString) -> PdfString, h: &SecurityHandler, num: u32, generation: u16, pass: Pass) -> Object {
-    let decrypt = pass == Pass::Decrypt;
+/// `d`, a signature dictionary, with the strings of everything but its `/Contents` transformed.
+fn signature_dict(d: &Dict, strings: &dyn Fn(&PdfString) -> PdfString) -> Object {
+    Object::Dict(
+        d.iter()
+            .map(|(k, v)| match (k.as_slice(), v) {
+                (b"Contents", Object::String(_)) => (k.clone(), v.clone()),
+                _ => (k.clone(), walk(v, strings)),
+            })
+            .collect(),
+    )
+}
+
+fn walk(o: &Object, strings: &dyn Fn(&PdfString) -> PdfString) -> Object {
     match o {
         Object::String(s) => Object::String(strings(s)),
-        Object::Array(a) => Object::Array(a.iter().map(|x| walk(x, strings, h, num, generation, pass)).collect()),
-        Object::Dict(d) if is_signature_dict(d) => Object::Dict(
-            d.iter()
-                .map(|(k, v)| match (k.as_slice(), v) {
-                    (b"Contents", Object::String(_)) => (k.clone(), v.clone()),
-                    _ => (k.clone(), walk(v, strings, h, num, generation, pass)),
-                })
-                .collect(),
-        ),
-        Object::Dict(d) => Object::Dict(d.iter().map(|(k, v)| (k.clone(), walk(v, strings, h, num, generation, pass))).collect()),
-        Object::Stream(s) => {
-            let mut dict: Dict = s.dict.iter().map(|(k, v)| (k.clone(), walk(v, strings, h, num, generation, pass))).collect();
-            let ty = s.dict.name(b"Type");
-            // Cross-reference streams are never encrypted (§7.5.8), but only reading may trust the
-            // label: a stream a producer calls /XRef stays plaintext if writing believes it, and the
-            // writer builds its own cross-reference streams outside this transform.
-            if (decrypt && ty == Some(b"XRef")) || (ty == Some(b"Metadata") && !h.encrypts_metadata()) {
-                return Object::Stream(Stream { dict, raw: s.raw.clone() });
-            }
-            let mut named = named_crypt_filter(&s.dict);
-            if pass == Pass::EncryptReplacing && named.as_deref().is_some_and(|n| !h.dict().crypt_filters.iter().any(|(f, _)| f == n)) {
-                drop_crypt_filter(&mut dict);
-                named = None;
-            }
-            let kind = match (&named, ty) {
-                (Some(n), _) => StreamKind::Named(n),
-                (None, Some(b"EmbeddedFile")) => StreamKind::EmbeddedFile,
-                _ => StreamKind::Normal,
-            };
-            let raw = if decrypt { h.decrypt_stream(num, generation, &s.raw, kind) } else { h.encrypt_stream(num, generation, &s.raw, kind) };
-            Object::Stream(Stream { dict, raw: raw.into() })
-        }
+        Object::Array(a) => Object::Array(a.iter().map(|x| walk(x, strings)).collect()),
+        Object::Dict(d) if is_signature_dict(None, d) => signature_dict(d, strings),
+        Object::Dict(d) => Object::Dict(d.iter().map(|(k, v)| (k.clone(), walk(v, strings))).collect()),
         other => other.clone(),
     }
 }
+
+fn stream(
+    doc: &Document,
+    s: &Stream,
+    strings: &dyn Fn(&PdfString) -> PdfString,
+    h: &SecurityHandler,
+    num: u32,
+    generation: u16,
+    pass: Pass,
+) -> Object {
+    let decrypt = pass == Pass::Decrypt;
+    let walked = |d: &Dict| -> Dict { d.iter().map(|(k, v)| (k.clone(), walk(v, strings))).collect() };
+    let ty = s.dict.get(b"Type").map(|t| followed(doc, t));
+    let ty = ty.as_deref().and_then(Object::as_name);
+    // Cross-reference streams are never encrypted (§7.5.8), but only reading may trust the
+    // label: a stream a producer calls /XRef stays plaintext if writing believes it, and the
+    // writer builds its own cross-reference streams outside this transform.
+    if (decrypt && ty == Some(b"XRef")) || (ty == Some(b"Metadata") && !h.encrypts_metadata()) {
+        return Object::Stream(Stream { dict: walked(&s.dict), raw: s.raw.clone() });
+    }
+    let mut named = named_crypt_filter(doc, &s.dict);
+    // Before the walk, which then encrypts what is in the dictionary this leaves.
+    let foreign = pass == Pass::EncryptReplacing && named.as_deref().is_some_and(|n| !h.dict().crypt_filters.iter().any(|(f, _)| f == n));
+    let dropped = foreign.then(|| drop_crypt_filter(doc, s));
+    if dropped.is_some() {
+        named = None;
+    }
+    let dict = walked(dropped.as_ref().unwrap_or(&s.dict));
+    let kind = match (&named, ty) {
+        (Some(n), _) => StreamKind::Named(n),
+        (None, Some(b"EmbeddedFile")) => StreamKind::EmbeddedFile,
+        _ => StreamKind::Normal,
+    };
+    let raw = if decrypt { h.decrypt_stream(num, generation, &s.raw, kind) } else { h.encrypt_stream(num, generation, &s.raw, kind) };
+    Object::Stream(Stream { dict, raw: raw.into() })
+}

crates/cos/src/writer.rs

@@ -133,11 +133,12 @@ fn write_stream(s: &Stream, out: &mut Vec<u8>) {
 
 /// The object as written: encrypted with its (output) number when the document is encrypted,
 /// except the `/Encrypt` dictionary itself (`source_num` is its number in the source document).
+/// `o` has the document's numbers in its references ([`crate::security::transform`]).
 fn prepared<'a>(doc: &Document, source_num: u32, num: u32, generation: u16, o: &'a Object) -> Cow<'a, Object> {
     match doc.output_security() {
-        (Some(h), encrypt_num) if Some(source_num) != encrypt_num => {
+        (Some(h), encrypt_num) if Some(source_num) != encrypt_num && !doc.stored_as_is(source_num) => {
             let pass = if doc.encryption_changed() { crate::security::Pass::EncryptReplacing } else { crate::security::Pass::Encrypt };
-            Cow::Owned(crate::security::transform(h, o, num, generation, pass))
+            Cow::Owned(crate::security::transform(doc, h, o, num, generation, pass))
         }
         _ => Cow::Borrowed(o),
     }
@@ -287,6 +288,10 @@ pub fn write_full(doc: &Document, opts: &SaveOptions) -> Result<Vec<u8>, CosErro
             queue.push_back(r);
         }
     }
+    // A direct /Encrypt can refer to objects, /CF or /StmF, say.
+    if let Some(encrypt @ Object::Dict(_)) = trailer_in.get(b"Encrypt") {
+        visit_refs(encrypt, &mut queue);
+    }
     // Unknown trailer entries are document data. Objects they alone reference must be written
     // too, or a full rewrite would keep the key and drop its value.
     for (key, value) in trailer_in.iter() {
@@ -315,7 +320,10 @@ pub fn write_full(doc: &Document, opts: &SaveOptions) -> Result<Vec<u8>, CosErro
     // The /Encrypt dictionary and everything it references (e.g. indirect /CF crypt-filter
     // dictionaries) are needed before anything can be decrypted: never inside object streams.
     let mut encryption_objects: std::collections::HashSet<ObjRef> = std::collections::HashSet::new();
-    let mut pending: Vec<ObjRef> = trailer_in.reference(b"Encrypt").into_iter().collect();
+    let mut pending: Vec<ObjRef> = Vec::new();
+    if let Some(encrypt) = trailer_in.get(b"Encrypt") {
+        collect_refs(encrypt, &mut |r| pending.push(r));
+    }
     while let Some(r) = pending.pop() {
         if encryption_objects.insert(r) {
             collect_refs(&reader.get(r), &mut |x| pending.push(x));
@@ -336,9 +344,10 @@ pub fn write_full(doc: &Document, opts: &SaveOptions) -> Result<Vec<u8>, CosErro
         if in_stream {
             packed.push((num, *r));
         } else {
-            let o = renumber(&*reread(&mut reader, *r, *is_stream)?, &map);
+            let o = reread(&mut reader, *r, *is_stream)?;
+            let o = renumber(&prepared(&reader.document, r.num, num, 0, &o), &map);
             rows.insert(num, Row::InFile(out.len() as u64, 0));
-            write_indirect(num, 0, &prepared(&reader.document, r.num, num, 0, &o), &mut out);
+            write_indirect(num, 0, &o, &mut out);
         }
     }
     // Object streams take the numbers after the last object. Their contents are not encrypted
@@ -368,11 +377,11 @@ pub fn write_full(doc: &Document, opts: &SaveOptions) -> Result<Vec<u8>, CosErro
             trailer.set(key.to_vec(), Object::Ref(ObjRef::new(*r, 0)));
         }
     }
-    if let Some(Object::Dict(d)) = trailer_in.get(b"Encrypt") {
-        trailer.set(b"Encrypt".to_vec(), Object::Dict(d.clone()));
+    if let Some(encrypt @ Object::Dict(_)) = trailer_in.get(b"Encrypt") {
+        trailer.set(b"Encrypt".to_vec(), renumber(encrypt, &map));
     }
     if let Some(id) = trailer_in.get(b"ID") {
-        trailer.set(b"ID".to_vec(), id.clone());
+        trailer.set(b"ID".to_vec(), direct_id(&reader.document, id));
     }
     for (key, value) in trailer_in.iter() {
         if !trailer_key_rewritten(key) {
@@ -442,6 +451,22 @@ impl ObjectStreamBatch {
     }
 }
 
+/// `/ID` for the trailer, direct, as it has to be with `/Encrypt`: nothing else in the file holds
+/// what it refers to now. Given by reference it is two entries at most, however many references a
+/// file gave, so that one large string isn't copied for each. An entry that isn't a string stays in
+/// its place as an empty one, which is how the key read it.
+fn direct_id(doc: &Document, id: &Object) -> Object {
+    if matches!(id, Object::Array(a) if !a.iter().any(|s| matches!(s, Object::Ref(_)))) {
+        return id.clone();
+    }
+    let entry = |s: &Object| match &*doc.resolve(s) {
+        s @ Object::String(_) => s.clone(),
+        _ => Object::String(crate::PdfString { bytes: Vec::new(), hex: true }),
+    };
+    let held = doc.resolve(id);
+    Object::Array(held.as_array().into_iter().flatten().take(2).map(entry).collect())
+}
+
 /// Trailer keys a full rewrite generates itself. Everything else is copied, with references
 /// renumbered, so a save does not drop metadata the reader accepted.
 fn trailer_key_rewritten(key: &[u8]) -> bool {
@@ -486,7 +511,7 @@ pub(crate) fn unlinked_additions(doc: &Document) -> HashSet<u32> {
     pending.into_keys().collect()
 }
 
-fn collect_refs(o: &Object, f: &mut impl FnMut(ObjRef)) {
+pub(crate) fn collect_refs(o: &Object, f: &mut impl FnMut(ObjRef)) {
     match o {
         Object::Ref(r) => f(*r),
         Object::Array(a) => a.iter().for_each(|x| collect_refs(x, f)),
@@ -663,6 +688,15 @@ fn civil_from_days(days: i64) -> (i64, u32, u32) {
 
 #[cfg(test)]
 mod tests {
+    /// `/ID` by reference comes out direct, each entry where it was: the key is made from the first.
+    #[test]
+    fn a_file_identifier_keeps_its_entries_in_their_places() {
+        let doc = Document::new_empty();
+        let string = |bytes: &[u8]| Object::String(crate::PdfString { bytes: bytes.to_vec(), hex: true });
+        let nowhere = Object::Ref(ObjRef::new(9_999, 0));
+        assert_eq!(super::direct_id(&doc, &Object::Array(vec![nowhere, string(b"ab")])), Object::Array(vec![string(b""), string(b"ab")]));
+    }
+
     use proptest::prelude::*;
 
     use super::*;

crates/cos/tests/it/encryption.rs

@@ -494,3 +494,826 @@ fn a_stream_labelled_xref_is_encrypted_when_saved() {
     let bytes = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
     assert!(!bytes.windows(SECRET.len()).any(|w| w == SECRET.as_bytes()), "the labelled stream was written in the clear");
 }
+
+/// The content stream's reference.
+fn contents_of(doc: &Document) -> ObjRef {
+    let catalog = doc.get(doc.root().unwrap()).as_dict().cloned().unwrap();
+    let pages = doc.get(catalog.reference(b"Pages").unwrap()).as_dict().cloned().unwrap();
+    let page = doc.resolve(&pages.get(b"Kids").unwrap().as_array().unwrap()[0]).as_dict().cloned().unwrap();
+    page.reference(b"Contents").unwrap()
+}
+
+/// The content stream's data as loaded, whatever its filters say.
+fn raw_content(doc: &Document) -> String {
+    match &*doc.get(contents_of(doc)) {
+        Object::Stream(s) => String::from_utf8_lossy(&s.raw).trim().to_string(),
+        _ => panic!("no content stream"),
+    }
+}
+
+/// Gives the content stream the `/Filter` and `/DecodeParms` of `selector`.
+fn select(doc: &mut Document, (filter, parms): (Object, Object)) {
+    let contents = contents_of(doc);
+    let Object::Stream(mut s) = doc.get(contents).as_ref().clone() else { panic!("no content stream") };
+    s.dict.set(b"Filter".to_vec(), filter);
+    s.dict.set(b"DecodeParms".to_vec(), parms);
+    doc.set(contents, Object::Stream(s));
+}
+
+/// `/Crypt` naming `name`, in the `form`th spelling: all direct, then each part by reference.
+/// `None` past the last.
+fn selector(doc: &mut Document, form: usize, name: &str) -> Option<(Object, Object)> {
+    let crypt = Object::name("Crypt");
+    let parms = |n: Object| {
+        let mut d = pdfcraft_cos::Dict::new();
+        d.set(b"Name".to_vec(), n);
+        Object::Dict(d)
+    };
+    let named = parms(Object::name(name));
+    Some(match form {
+        0 => (crypt, named),
+        1 => (crypt, Object::Ref(doc.add(named))),
+        2 => (Object::Array(vec![crypt]), Object::Array(vec![Object::Ref(doc.add(named))])),
+        3 => (Object::Array(vec![crypt]), Object::Ref(doc.add(Object::Array(vec![named])))),
+        4 => (crypt, parms(Object::Ref(doc.add(Object::name(name))))),
+        5 => (Object::Ref(doc.add(crypt)), named),
+        6 => (Object::Ref(doc.add(Object::Array(vec![crypt]))), Object::Array(vec![named])),
+        7 => (Object::Array(vec![Object::Ref(doc.add(crypt))]), Object::Array(vec![named])),
+        // Behind a filter given by reference: places in the two arrays pair up all the same.
+        8 => (Object::Array(vec![Object::Ref(doc.add(Object::name("ASCIIHexDecode"))), crypt]), Object::Array(vec![Object::Null, named])),
+        // The two entries in different forms, which is how a lone filter is usually spelled.
+        9 => (Object::Array(vec![crypt]), named),
+        10 => (crypt, Object::Array(vec![named])),
+        // The filter twice, which names the first's.
+        11 => (Object::Array(vec![crypt.clone(), crypt]), Object::Array(vec![named.clone(), named])),
+        // A reference to a reference.
+        12 => {
+            let name = doc.add(Object::name(name));
+            let hop = doc.add(Object::Ref(name));
+            (crypt, parms(Object::Ref(hop)))
+        }
+        _ => return None,
+    })
+}
+
+fn holds(bytes: &[u8], text: &str) -> bool {
+    String::from_utf8_lossy(bytes).contains(text)
+}
+
+/// An object `/Encrypt` names is written as stored only while it is as stored. A file whose
+/// `/Encrypt` names its `/Info` reads that dictionary as stored; once the title is edited, both
+/// saves encrypt it rather than writing the new title in the clear.
+#[test]
+fn an_edited_object_that_encrypt_names_is_encrypted() {
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes128,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [9; 32],
+    })
+    .unwrap();
+    let info = doc.trailer().reference(b"Info").unwrap();
+    let mut dict = doc.get(doc.trailer().reference(b"Encrypt").unwrap()).as_dict().cloned().unwrap();
+    dict.set(b"Junk".to_vec(), Object::Ref(info));
+    doc.trailer_mut().set(b"Encrypt".to_vec(), Object::Dict(dict));
+    let bytes = write_full(&doc, &SaveOptions::default()).unwrap();
+    let mut doc = Document::open(Arc::new(bytes)).unwrap();
+    let info = doc.trailer().reference(b"Info").unwrap();
+    doc.update_dict(info, |d| d.set(b"Title".to_vec(), PdfString::text("Merger plan"))).unwrap();
+    for (save, saved) in [("incremental", write_incremental(&doc, &SaveOptions::default())), ("full", write_full(&doc, &SaveOptions::default()))] {
+        assert!(!holds(&saved.unwrap(), "Merger plan"), "{save}: the edited title was written in the clear");
+    }
+}
+
+/// A stream can select its crypt filter by reference at every step: the chain, an entry of it, the
+/// parameters, an entry of those, the name (ISO 32000-2 §7.3.10, §7.4.10). Read as absent, the
+/// filter was `/Identity`, so such a stream was saved in the clear and, in a file from elsewhere,
+/// its ciphertext read as data. A full save renumbers: what it follows has the document's numbers.
+#[test]
+fn a_crypt_filter_selected_by_reference_is_used() {
+    for alg in [Algorithm::Aes128, Algorithm::Aes256] {
+        for form in 0.. {
+            let mut doc = Document::open(Arc::new(protect(alg, "", "owner", -1))).unwrap();
+            let Some(selected) = selector(&mut doc, form, "StdCF") else { break };
+            select(&mut doc, selected);
+            let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+            assert!(!holds(&saved, "Secret page"), "{alg:?} form {form}: saved encrypted");
+            let back = Document::open(Arc::new(saved)).unwrap();
+            assert_eq!(raw_content(&back), SECRET, "{alg:?} form {form}: read back");
+            let full = write_full(&back, &SaveOptions::default()).unwrap();
+            assert!(!holds(&full, "Secret page"), "{alg:?} form {form}: renumbered, encrypted");
+            assert_eq!(raw_content(&Document::open(Arc::new(full)).unwrap()), SECRET, "{alg:?} form {form}: renumbered");
+        }
+    }
+}
+
+/// A reference to a stream that takes `follows` references to read cold, this one included: its
+/// nine filters are all read, the last leading to the next stream.
+fn spends(doc: &mut Document, follows: usize) -> Object {
+    let left = follows - 1;
+    let mut filters: Vec<Object> = (0..left.min(8)).map(|i| Object::Ref(doc.add(Object::Int(i as i64)))).collect();
+    if left > 8 {
+        filters.push(spends(doc, left - 8));
+    }
+    let mut dict = pdfcraft_cos::Dict::new();
+    dict.set(b"Filter".to_vec(), Object::Array(filters));
+    Object::Ref(doc.add(Object::Stream(pdfcraft_cos::Stream::from_raw(dict, Vec::new()))))
+}
+
+/// Gives the content stream a `/Type` that takes `follows` references to read, ahead of its filter.
+fn spend_first(doc: &mut Document, follows: usize) {
+    let spent = spends(doc, follows);
+    let contents = contents_of(doc);
+    let Object::Stream(mut s) = doc.get(contents).as_ref().clone() else { panic!("no content stream") };
+    s.dict.set(b"Type".to_vec(), spent);
+    doc.set(contents, Object::Stream(s));
+}
+
+/// Past what one read may follow a reference reads as absent, and a crypt filter with no `/Name` is
+/// `/Identity`. Together those would read this stream's ciphertext as data, so what can't be told
+/// is the document's own filter, as a `/Filter` that can't be read is.
+#[test]
+fn a_crypt_filter_past_what_a_read_may_follow_is_the_documents_own() {
+    let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+    let selected = selector(&mut doc, 1, "StdCF").unwrap();
+    select(&mut doc, selected);
+    spend_first(&mut doc, 40);
+    let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+    assert!(!holds(&saved, "Secret page"), "saved encrypted");
+    let back = Document::open(Arc::new(saved)).unwrap();
+    assert_eq!(raw_content(&back), SECRET);
+    let full = write_full(&back, &SaveOptions::default()).unwrap();
+    assert!(!holds(&full, "Secret page"), "renumbered, encrypted");
+    assert_eq!(raw_content(&Document::open(Arc::new(full)).unwrap()), SECRET, "renumbered");
+}
+
+/// A read that takes all it may follow has refused nothing: a crypt filter with no `/Name` after it
+/// is still `/Identity`, and the stream is in the clear.
+#[test]
+fn a_crypt_filter_with_no_name_after_all_a_read_may_follow_is_identity() {
+    let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+    select(&mut doc, (Object::name("Crypt"), Object::Dict(pdfcraft_cos::Dict::new())));
+    spend_first(&mut doc, 32);
+    let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+    assert!(holds(&saved, "Secret page"), "written as the stream asks");
+    assert_eq!(raw_content(&Document::open(Arc::new(saved)).unwrap()), SECRET);
+}
+
+/// `/Identity` selected by reference keeps a stream in the clear in a document that encrypts the
+/// rest, in every spelling, on both saves.
+#[test]
+fn an_identity_crypt_filter_selected_by_reference_leaves_a_stream_alone() {
+    for form in 0.. {
+        let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+        let Some(selected) = selector(&mut doc, form, "Identity") else { break };
+        select(&mut doc, selected);
+        let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+        assert!(holds(&saved, "Secret page"), "form {form}: written as the stream asks");
+        let back = Document::open(Arc::new(saved)).unwrap();
+        assert_eq!(raw_content(&back), SECRET, "form {form}");
+        let full = write_full(&back, &SaveOptions::default()).unwrap();
+        assert!(holds(&full, "Secret page"), "form {form}: renumbered");
+        assert_eq!(raw_content(&Document::open(Arc::new(full)).unwrap()), SECRET, "form {form}: renumbered");
+    }
+}
+
+/// New protection drops a crypt filter it doesn't define, whichever way the stream selected it. The
+/// chain comes out direct. Parameters in the stream's own dictionary stay, encrypted with it; of an
+/// array in an object of its own, which every stream can share, only what decoders read is copied.
+#[test]
+fn protecting_drops_a_crypt_filter_selected_by_reference() {
+    let protected = |doc: &mut Document| {
+        doc.set_encryption(&NewEncryption {
+            algorithm: Algorithm::Aes256,
+            user_password: "",
+            owner_password: "owner",
+            permissions: -1,
+            encrypt_metadata: true,
+            seed: [7; 32],
+        })
+        .unwrap();
+        write_full(doc, &SaveOptions::default()).unwrap()
+    };
+    for form in 0.. {
+        let mut doc = Document::open(Arc::new(fixture())).unwrap();
+        let Some(selected) = selector(&mut doc, form, "MyCF") else { break };
+        select(&mut doc, selected);
+        let bytes = protected(&mut doc);
+        assert!(!holds(&bytes, "Secret page"), "form {form}: encrypted");
+        assert!(!holds(&bytes, "MyCF"), "form {form}: no selector left in the stream");
+        let back = Document::open(Arc::new(bytes.clone())).unwrap();
+        assert_eq!(raw_content(&back), SECRET, "form {form}");
+        let contents = back.get(contents_of(&back));
+        let filter = contents.as_dict().unwrap().get(b"Filter");
+        match form {
+            8 => assert!(
+                matches!(filter, Some(Object::Array(a)) if matches!(a.as_slice(), [Object::Ref(_)])),
+                "form 8: the other filter stays: {filter:?}"
+            ),
+            _ => assert_eq!(filter, None, "form {form}"),
+        }
+        assert!(hayro_syntax::Pdf::new(bytes).is_ok(), "form {form}");
+    }
+    for shared in [false, true] {
+        let mut doc = Document::open(Arc::new(fixture())).unwrap();
+        let mut named = pdfcraft_cos::Dict::new();
+        named.set(b"Name".to_vec(), Object::name("MyCF"));
+        let mut other = pdfcraft_cos::Dict::new();
+        other.set(b"Note".to_vec(), Object::String(PdfString::text("Private note")));
+        other.set(b"Predictor".to_vec(), Object::Int(1));
+        let parms = Object::Array(vec![Object::Dict(named), Object::Dict(other)]);
+        let parms = if shared { Object::Ref(doc.add(parms)) } else { parms };
+        select(&mut doc, (Object::Array(vec![Object::name("Crypt"), Object::name("ASCIIHexDecode")]), parms));
+        let bytes = protected(&mut doc);
+        assert!(!holds(&bytes, "Private note"), "shared: {shared}");
+        let back = Document::open(Arc::new(bytes)).unwrap();
+        let contents = back.get(contents_of(&back));
+        let kept = contents.as_dict().unwrap().get(b"DecodeParms").unwrap().as_array().unwrap();
+        assert_eq!(kept.len(), 1, "one filter left, one entry");
+        let kept = kept[0].as_dict().unwrap();
+        assert_eq!(kept.get(b"Predictor"), Some(&Object::Int(1)), "shared: {shared}");
+        assert_eq!(kept.get(b"Note").is_some(), !shared, "shared: {shared}");
+    }
+}
+
+/// Every stream of a file can share one large object as its `/DecodeParms` or `/Filter`, which
+/// costs nothing until new protection drops a crypt filter from each. Copied whole, a 1 MB file
+/// came out at 1 GB.
+#[test]
+fn protecting_copies_no_large_object_into_every_stream() {
+    let pad = Object::Array(vec![Object::Int(1); 100_000]);
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    let mut large = pdfcraft_cos::Dict::new();
+    large.set(b"Pad".to_vec(), pad.clone());
+    let parms = doc.add(Object::Array(vec![Object::Null, Object::Dict(large)]));
+    let filter = doc.add(Object::Array(vec![Object::name("Crypt"), Object::Name(vec![b'A'; 100_000]), pad]));
+    let mut streams = Vec::new();
+    for _ in 0..200 {
+        let mut by_parms = pdfcraft_cos::Dict::new();
+        by_parms.set(b"Filter".to_vec(), Object::Array(vec![Object::name("Crypt"), Object::name("ASCIIHexDecode")]));
+        by_parms.set(b"DecodeParms".to_vec(), Object::Ref(parms));
+        streams.push(Object::Ref(doc.add(Object::Stream(pdfcraft_cos::Stream::from_raw(by_parms, b"41>".to_vec())))));
+        let mut by_filter = pdfcraft_cos::Dict::new();
+        by_filter.set(b"Filter".to_vec(), Object::Ref(filter));
+        streams.push(Object::Ref(doc.add(Object::Stream(pdfcraft_cos::Stream::from_raw(by_filter, b"41>".to_vec())))));
+    }
+    doc.update_dict(doc.root().unwrap(), |c| c.set(b"Test".to_vec(), Object::Array(streams))).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes256,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [7; 32],
+    })
+    .unwrap();
+    let bytes = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
+    assert!(bytes.len() < 1 << 20, "{} bytes", bytes.len());
+}
+
+/// A file can name one large string thousands of times in `/ID`, which holds two. An encrypted file
+/// keeps its `/ID`, so each copy would be in the file a save writes.
+#[test]
+fn a_file_identifier_of_many_references_is_two_strings() {
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes128,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [9; 32],
+    })
+    .unwrap();
+    let large = doc.add(Object::String(PdfString { bytes: vec![0xAB; 100_000], hex: true }));
+    doc.trailer_mut().set(b"ID".to_vec(), Object::Array(vec![Object::Ref(large); 500]));
+    let bytes = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
+    assert!(bytes.len() < 1 << 20, "{} bytes", bytes.len());
+}
+
+/// What a file can do with those references: point a stream's selector at the stream itself, or at
+/// nothing. They read as absent, so a stream with `/Crypt` is `/Identity` (ISO 32000-2 §7.4.10),
+/// and one that names no filter follows the document's. Loading ends either way.
+#[test]
+fn a_crypt_filter_reference_to_itself_or_nothing_reads_as_absent() {
+    let named = |n: Object| {
+        let mut d = pdfcraft_cos::Dict::new();
+        d.set(b"Name".to_vec(), n);
+        Object::Dict(d)
+    };
+    for (what, encrypted) in [
+        ("/Filter to itself", true),
+        ("/Filter nowhere", true),
+        ("/DecodeParms to itself", false),
+        ("/DecodeParms nowhere", false),
+        ("/Name to itself", false),
+        ("/Name nowhere", false),
+    ] {
+        let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+        let me = Object::Ref(contents_of(&doc));
+        let nowhere = Object::Ref(ObjRef::new(9_999, 0));
+        let crypt = Object::name("Crypt");
+        select(
+            &mut doc,
+            match what {
+                "/Filter to itself" => (me, Object::Null),
+                "/Filter nowhere" => (nowhere, Object::Null),
+                "/DecodeParms to itself" => (crypt, me),
+                "/DecodeParms nowhere" => (crypt, nowhere),
+                "/Name to itself" => (crypt, named(me)),
+                _ => (crypt, named(nowhere)),
+            },
+        );
+        let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+        assert_eq!(!holds(&saved, "Secret page"), encrypted, "{what}");
+        assert_eq!(raw_content(&Document::open(Arc::new(saved)).unwrap()), SECRET, "{what}");
+    }
+}
+
+/// A lone parameter dictionary belongs to the first filter, so `/Crypt` behind another filter has
+/// none of its own and is `/Identity` (ISO 32000-2 §7.4.1), whatever that dictionary says.
+#[test]
+fn a_lone_parameter_dictionary_is_the_first_filters() {
+    let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+    let mut parms = pdfcraft_cos::Dict::new();
+    parms.set(b"Name".to_vec(), Object::name("StdCF"));
+    let first = Object::Array(vec![Object::name("Crypt"), Object::name("ASCIIHexDecode")]);
+    let second = Object::Array(vec![Object::name("ASCIIHexDecode"), Object::name("Crypt")]);
+    select(&mut doc, (first, Object::Dict(parms.clone())));
+    assert!(!holds(&write_incremental(&doc, &SaveOptions::default()).unwrap(), "Secret page"), "first: it names StdCF");
+    select(&mut doc, (second, Object::Dict(parms)));
+    assert!(holds(&write_incremental(&doc, &SaveOptions::default()).unwrap(), "Secret page"), "second: it names nothing");
+}
+
+/// A lone parameter dictionary is the first filter's, so dropping a `/Crypt` behind that filter
+/// leaves it, and dropping one in front of it takes it away.
+#[test]
+fn protecting_keeps_the_parameters_of_the_filter_before_a_crypt_filter() {
+    let protected = |filters: Vec<Object>| {
+        let mut doc = Document::open(Arc::new(fixture())).unwrap();
+        let mut parms = pdfcraft_cos::Dict::new();
+        parms.set(b"Name".to_vec(), Object::name("MyCF"));
+        select(&mut doc, (Object::Array(filters), Object::Dict(parms)));
+        doc.set_encryption(&NewEncryption {
+            algorithm: Algorithm::Aes256,
+            user_password: "",
+            owner_password: "owner",
+            permissions: -1,
+            encrypt_metadata: true,
+            seed: [7; 32],
+        })
+        .unwrap();
+        let back = Document::open(Arc::new(write_full(&doc, &SaveOptions::default()).unwrap())).unwrap();
+        back.get(contents_of(&back)).as_dict().unwrap().contains(b"DecodeParms")
+    };
+    let (hex, crypt) = (Object::name("ASCIIHexDecode"), Object::name("Crypt"));
+    assert!(protected(vec![hex.clone(), crypt.clone()]), "the first filter's, which stays");
+    assert!(!protected(vec![crypt, hex]), "/Crypt's, which goes");
+}
+
+/// Dropping `/Crypt` takes its entry out of `/DecodeParms`, and an array too short to have one is
+/// left as it is, given directly or by reference.
+#[test]
+fn protecting_leaves_a_parameter_array_too_short_for_the_crypt_filter() {
+    for by_reference in [false, true] {
+        let mut doc = Document::open(Arc::new(fixture())).unwrap();
+        let short = Object::Array(vec![Object::Null]);
+        let parms = if by_reference { Object::Ref(doc.add(short)) } else { short };
+        select(&mut doc, (Object::Array(vec![Object::name("ASCIIHexDecode"), Object::name("Crypt")]), parms));
+        doc.set_encryption(&NewEncryption {
+            algorithm: Algorithm::Aes256,
+            user_password: "",
+            owner_password: "owner",
+            permissions: -1,
+            encrypt_metadata: true,
+            seed: [7; 32],
+        })
+        .unwrap();
+        let bytes = write_full(&doc, &SaveOptions::default()).unwrap();
+        assert!(!holds(&bytes, "Secret page"), "by reference: {by_reference}");
+        let back = Document::open(Arc::new(bytes)).unwrap();
+        assert_eq!(raw_content(&back), SECRET, "by reference: {by_reference}");
+        let contents = back.get(contents_of(&back));
+        let filter = contents.as_dict().unwrap().get(b"Filter").unwrap().as_array().unwrap();
+        assert_eq!(filter.len(), 1, "only /Crypt goes");
+        assert_eq!(filter[0].as_name(), Some(b"ASCIIHexDecode".as_slice()), "the other filter stays as it was");
+    }
+}
+
+/// A chain of up to [`pdfcraft_filters::MAX_CHAIN`] filters and `/Crypt` is read; a longer one
+/// names no crypt filter, so its entries aren't followed for every stream sharing it.
+#[test]
+fn a_chain_longer_than_any_decoder_takes_names_no_crypt_filter() {
+    let chain = |others: usize| {
+        let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+        let mut filters = vec![Object::name("ASCIIHexDecode"); others];
+        filters.push(Object::name("Crypt"));
+        let array = doc.add(Object::Array(filters));
+        select(&mut doc, (Object::Ref(array), Object::Null));
+        holds(&write_incremental(&doc, &SaveOptions::default()).unwrap(), "Secret page")
+    };
+    assert!(chain(pdfcraft_filters::MAX_CHAIN), "the longest chain read: /Identity, in the clear");
+    assert!(!chain(pdfcraft_filters::MAX_CHAIN + 1), "one more: the document's filter");
+}
+
+/// A stream's `/Type` by reference picks its handling like one given directly: metadata left
+/// readable under `/EncryptMetadata false`, an embedded file under `/EFF`.
+#[test]
+fn a_stream_type_given_by_reference_picks_its_crypt_filter() {
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    let catalog = doc.get(doc.root().unwrap()).as_dict().cloned().unwrap();
+    let meta = catalog.reference(b"Metadata").unwrap();
+    let ty = doc.add(Object::name("Metadata"));
+    let Object::Stream(mut s) = doc.get(meta).as_ref().clone() else { panic!("no metadata stream") };
+    s.dict.set(b"Type".to_vec(), Object::Ref(ty));
+    doc.set(meta, Object::Stream(s));
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes256,
+        user_password: "",
+        owner_password: "o",
+        permissions: -1,
+        encrypt_metadata: false,
+        seed: [5; 32],
+    })
+    .unwrap();
+    let bytes = write_full(&doc, &SaveOptions::default()).unwrap();
+    assert!(holds(&bytes, "<x:xmpmeta>meta</x:xmpmeta>"), "search engines can read XMP");
+
+    let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+    let encrypt = doc.trailer().reference(b"Encrypt").unwrap();
+    doc.update_dict(encrypt, |e| e.set(b"EFF".to_vec(), Object::name("Identity"))).unwrap();
+    let mut doc = Document::open(Arc::new(write_incremental(&doc, &SaveOptions::default()).unwrap())).unwrap();
+    let contents = contents_of(&doc);
+    let ty = doc.add(Object::name("EmbeddedFile"));
+    let Object::Stream(mut s) = doc.get(contents).as_ref().clone() else { panic!("no content stream") };
+    s.dict.set(b"Type".to_vec(), Object::Ref(ty));
+    doc.set(contents, Object::Stream(s));
+    assert!(holds(&write_incremental(&doc, &SaveOptions::default()).unwrap(), "Secret page"), "/EFF /Identity leaves it alone");
+}
+
+/// What makes a dictionary a signature's can be given by reference, and what is null or refers to
+/// nothing is absent: `/Contents` stays as written in each of these.
+#[test]
+fn a_signature_dictionary_is_known_in_every_form() {
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    let ty = doc.add(Object::name("Sig"));
+    let range = Object::Array([0, 10, 20, 30].into_iter().map(Object::Int).collect());
+    let by_reference = doc.add(range.clone());
+    let nowhere = Object::Ref(ObjRef::new(9_999, 0));
+    let forms: [(Vec<(&str, Object)>, &str); 5] = [
+        (vec![("Type", Object::Ref(ty))], "DEAD"),
+        (vec![("ByteRange", Object::Ref(by_reference))], "BEEF"),
+        (vec![("Type", Object::Null), ("ByteRange", range.clone())], "CAFE"),
+        (vec![("Type", nowhere.clone()), ("ByteRange", range.clone())], "F00D"),
+        (vec![("Subtype", nowhere), ("ByteRange", range)], "D00D"),
+    ];
+    let mut signatures = Vec::new();
+    for (entries, contents) in forms {
+        let mut sig = pdfcraft_cos::Dict::new();
+        for (key, value) in entries {
+            sig.set(key.as_bytes().to_vec(), value);
+        }
+        let bytes = (0..contents.len()).step_by(2).map(|i| u8::from_str_radix(&contents[i..i + 2], 16).unwrap()).collect();
+        sig.set(b"Contents".to_vec(), Object::String(PdfString { bytes, hex: true }));
+        signatures.push(Object::Ref(doc.add(Object::Dict(sig))));
+    }
+    // Nested in another object, it follows nothing, but known directly it is one all the same.
+    let mut nested = pdfcraft_cos::Dict::new();
+    nested.set(b"Type".to_vec(), Object::name("Sig"));
+    nested.set(b"Contents".to_vec(), Object::String(PdfString { bytes: vec![0xAB, 0xBA], hex: true }));
+    let mut field = pdfcraft_cos::Dict::new();
+    field.set(b"V".to_vec(), Object::Dict(nested));
+    signatures.push(Object::Ref(doc.add(Object::Dict(field))));
+    // Neither of what makes one: a string /Contents alone is anybody's, so it's encrypted.
+    let mut other = pdfcraft_cos::Dict::new();
+    other.set(b"Contents".to_vec(), Object::String(PdfString { bytes: vec![0xAB, 0xCD], hex: true }));
+    signatures.push(Object::Ref(doc.add(Object::Dict(other))));
+    doc.update_dict(doc.root().unwrap(), |c| c.set(b"Test".to_vec(), Object::Array(signatures))).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes256,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [3; 32],
+    })
+    .unwrap();
+    let bytes = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
+    for contents in ["DEAD", "BEEF", "CAFE", "F00D", "D00D", "ABBA"] {
+        assert!(holds(&bytes, &format!("<{contents}>")), "{contents}: written as is");
+    }
+    assert!(!holds(&bytes, "<ABCD>"), "without a /ByteRange it is no signature");
+}
+
+/// What a test needs to write an update of a classic file protected with AES-128.
+struct Classic {
+    bytes: Vec<u8>,
+    root: ObjRef,
+    pages: ObjRef,
+    info: ObjRef,
+    encrypt: ObjRef,
+    id: Vec<u8>,
+    dict: pdfcraft_cos::Dict,
+}
+
+fn classic_file() -> Classic {
+    let mut doc = Document::open(Arc::new(fixture())).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes128,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [9; 32],
+    })
+    .unwrap();
+    let bytes = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
+    let doc = Document::open(Arc::new(bytes.clone())).unwrap();
+    let encrypt = doc.trailer().reference(b"Encrypt").unwrap();
+    let id = doc.trailer().get(b"ID").unwrap().as_array().unwrap()[0].as_string().unwrap().bytes.clone();
+    let dict = doc.get(encrypt).as_dict().cloned().unwrap();
+    let pages = doc.get(doc.root().unwrap()).as_dict().unwrap().reference(b"Pages").unwrap();
+    Classic { root: doc.root().unwrap(), pages, info: doc.trailer().reference(b"Info").unwrap(), bytes, encrypt, id, dict }
+}
+
+fn hex(bytes: &[u8]) -> String {
+    bytes.iter().map(|b| format!("{b:02X}")).collect()
+}
+
+/// `bytes` with an update appended: `objects`, and a trailer of `trailer` entries, in which `@n`
+/// stands for the offset of object `n`. An object with nothing in it gets an entry of the
+/// cross-reference table that points at nothing.
+fn updated(bytes: &[u8], objects: &[(u32, Vec<u8>)], trailer: &str) -> Vec<u8> {
+    let at = bytes.windows(9).rposition(|w| w == b"startxref").unwrap();
+    let prev: usize = String::from_utf8_lossy(&bytes[at + 9..]).split_whitespace().next().unwrap().parse().unwrap();
+    let mut out = bytes.to_vec();
+    let mut table = String::from("xref\n");
+    let mut trailer = trailer.to_string();
+    for (num, body) in objects {
+        if body.is_empty() {
+            table.push_str(&format!("{num} 1\n0000000010 00000 n \n"));
+            continue;
+        }
+        trailer = trailer.replace(&format!("@{num}"), &out.len().to_string());
+        table.push_str(&format!("{num} 1\n{:010} 00000 n \n", out.len()));
+        out.extend_from_slice(format!("{num} 0 obj\n").as_bytes());
+        out.extend_from_slice(body);
+        out.extend_from_slice(b"\nendobj\n");
+    }
+    let xref = out.len();
+    out.extend_from_slice(table.as_bytes());
+    out.extend_from_slice(format!("trailer\n<< {trailer} /Size 2000 /Prev {prev} >>\nstartxref\n{xref}\n%%EOF\n").as_bytes());
+    out
+}
+
+/// The `/Encrypt` dictionary of `file`, with `/O`, `/StmF` and `/StrF` as given.
+fn encrypt_with(file: &Classic, o: &str, filter: &str) -> Vec<u8> {
+    let string = |key: &[u8]| hex(&file.dict.get(key).unwrap().as_string().unwrap().bytes);
+    format!(
+        "<< /Filter /Standard /V 4 /R 4 /Length 128 /P {} /O {o} /U <{}> /CF << /StdCF << /CFM /AESV2 /Length 16 /AuthEvent /DocOpen >> >> /StmF /{filter} /StrF /{filter} >>",
+        file.dict.int(b"P").unwrap(),
+        string(b"U")
+    )
+    .into_bytes()
+}
+
+/// An object stream can have its parameters by reference, and a stream's crypt filter can be
+/// selected by a member of it: legal together, though each is rare. What reads the stream first
+/// goes through the object stream, and members must come out of it as they do read directly. They
+/// didn't, while a read made for a selector wasn't allowed to follow its own: the object stream was
+/// kept undecoded, its members lost for good, and a full save wrote nulls without saying so.
+#[test]
+fn an_object_stream_reached_from_a_selector_keeps_its_members() {
+    let file = classic_file();
+    let parms = "[<< /Name /Identity >> null]";
+    let header = format!("902 0 903 {} ", parms.len() + 1);
+    let members = format!("{header}{parms} << /Keep (yes) >>");
+    let (mut rows, mut before) = (vec![1u8], 0u8);
+    for b in members.bytes() {
+        rows.push(b.wrapping_sub(before));
+        before = b;
+    }
+    let coded = pdfcraft_cos::Stream::flate(pdfcraft_cos::Dict::new(), &rows).raw;
+    let mut object_stream =
+        format!("<< /Type /ObjStm /N 2 /First {} /Filter /FlateDecode /DecodeParms 911 0 R /Length {} >>\nstream\n", header.len(), coded.len())
+            .into_bytes();
+    object_stream.extend_from_slice(&coded);
+    object_stream.extend_from_slice(b"\nendstream");
+    let data = [2u8, 0x03, 0x8E, 0, 2, 0x03, 0x8E, 1];
+    let mut xref = format!("<< /Type /XRef /Size 2000 /W [1 2 1] /Index [902 2] /Length {} >>\nstream\n", data.len()).into_bytes();
+    xref.extend_from_slice(&data);
+    xref.extend_from_slice(b"\nendstream");
+    let string = |key: &[u8]| format!("<{}>", hex(&file.dict.get(key).unwrap().as_string().unwrap().bytes));
+    let objects = [
+        (file.root.num, format!("<< /Type /Catalog /Pages {} 0 R /A 900 0 R /B 903 0 R >>", file.pages.num).into_bytes()),
+        (file.encrypt.num, encrypt_with(&file, &string(b"O"), "Identity")),
+        (900, b"<< /Filter [/Crypt /ASCIIHexDecode] /DecodeParms 902 0 R /Length 1 >>\nstream\n>\nendstream".to_vec()),
+        (910, object_stream),
+        (911, format!("<< /Predictor 11 /Columns {} >>", members.len()).into_bytes()),
+        (912, xref),
+    ];
+    let trailer = format!("/Root {} 0 R /Encrypt {} 0 R /ID [<{id}> <{id}>] /XRefStm @912", file.root.num, file.encrypt.num, id = hex(&file.id));
+    let bytes = updated(&file.bytes, &objects, &trailer);
+    let keep =
+        |doc: &Document, r: &Object| doc.resolve(r).as_dict().and_then(|d| d.get(b"Keep")).and_then(Object::as_string).map(|s| s.bytes.clone());
+    let member = Object::Ref(ObjRef::new(903, 0));
+    let doc = Document::open(Arc::new(bytes.clone())).unwrap();
+    assert_eq!(keep(&doc, &member).as_deref(), Some(b"yes".as_slice()), "read first");
+    let doc = Document::open(Arc::new(bytes.clone())).unwrap();
+    let _ = doc.get(ObjRef::new(900, 0));
+    assert_eq!(keep(&doc, &member).as_deref(), Some(b"yes".as_slice()), "read after the stream selecting from it");
+    let saved = write_full(&Document::open(Arc::new(bytes)).unwrap(), &SaveOptions::default()).unwrap();
+    let back = Document::open(Arc::new(saved)).unwrap();
+    let catalog = back.get(back.root().unwrap());
+    assert_eq!(keep(&back, catalog.as_dict().unwrap().get(b"B").unwrap()).as_deref(), Some(b"yes".as_slice()), "after a full save");
+}
+
+/// `walk` goes as deep as an object nests, so following a reference from down there adds that depth
+/// again for each object it loads: this file, under 10 KB, overflowed a 2 MiB stack and took the
+/// process with it. Only the object itself follows references, and it does so in very little stack.
+#[test]
+fn nested_dictionaries_load_nothing_on_a_small_stack() {
+    let file = classic_file();
+    let first = 960u32;
+    let objects: Vec<(u32, Vec<u8>)> = (first..first + 40)
+        .map(|num| {
+            let open = "[".repeat(120);
+            let close = "]".repeat(120);
+            (num, format!("{open}<< /Contents () /Type {} 0 R >>{close}", num + 1).into_bytes())
+        })
+        .collect();
+    let trailer = format!("/Root {} 0 R /Encrypt {} 0 R /ID [<{id}> <{id}>]", file.root.num, file.encrypt.num, id = hex(&file.id));
+    let bytes = updated(&file.bytes, &objects, &trailer);
+    let reading = std::thread::Builder::new().stack_size(1 << 20).spawn(move || {
+        let doc = Document::open(Arc::new(bytes)).unwrap();
+        doc.get(ObjRef::new(first, 0)).as_array().is_some()
+    });
+    assert_eq!(reading.unwrap().join().ok(), Some(true));
+}
+
+/// The object itself can follow references, a ladder of them as long as loading may nest, and that
+/// fits a small stack too.
+#[test]
+fn a_ladder_of_signature_checks_fits_a_small_stack() {
+    let file = classic_file();
+    let first = 960u32;
+    let objects: Vec<(u32, Vec<u8>)> =
+        (first..first + 40).map(|num| (num, format!("<< /Contents () /Type {} 0 R >>", num + 1).into_bytes())).collect();
+    let trailer = format!("/Root {} 0 R /Encrypt {} 0 R /ID [<{id}> <{id}>]", file.root.num, file.encrypt.num, id = hex(&file.id));
+    let bytes = updated(&file.bytes, &objects, &trailer);
+    let reading = std::thread::Builder::new().stack_size(1 << 20).spawn(move || {
+        let doc = Document::open(Arc::new(bytes)).unwrap();
+        doc.get(ObjRef::new(first, 0)).as_dict().is_some()
+    });
+    assert_eq!(reading.unwrap().join().ok(), Some(true));
+}
+
+/// The strings of `/Encrypt` are never encrypted (ISO 32000-2 §7.6.2), and can be objects of their
+/// own. Read as ordinary strings they were decrypted, and a full save encrypted them again under
+/// another number, so the file it wrote no longer opened with its own password.
+#[test]
+fn encrypt_strings_given_by_reference_stay_as_stored() {
+    let file = classic_file();
+    let string = |key: &[u8]| hex(&file.dict.get(key).unwrap().as_string().unwrap().bytes);
+    let replaced = format!(
+        "<< /Filter /Standard /V 4 /R 4 /Length 128 /P {} /O 900 0 R /U 901 0 R /CF << /StdCF << /CFM /AESV2 /Length 16 /AuthEvent /DocOpen >> >> /StmF /StdCF /StrF /StdCF >>",
+        file.dict.int(b"P").unwrap()
+    );
+    let objects = [
+        (file.encrypt.num, replaced.into_bytes()),
+        (900, format!("<{}>", string(b"O")).into_bytes()),
+        (901, format!("<{}>", string(b"U")).into_bytes()),
+    ];
+    let trailer =
+        format!("/Root {} 0 R /Info {} 0 R /Encrypt {} 0 R /ID [<{id}> <{id}>]", file.root.num, file.info.num, file.encrypt.num, id = hex(&file.id));
+    let source = Document::open(Arc::new(updated(&file.bytes, &objects, &trailer))).unwrap();
+    assert_eq!(content(&source), SECRET, "the file reads");
+    assert_eq!(title(&source).as_deref(), Some("Quarterly numbers"));
+    for object_streams in [false, true] {
+        let saved = write_full(&source, &SaveOptions { object_streams, ..SaveOptions::default() }).unwrap();
+        let back = Document::open(Arc::new(saved)).unwrap();
+        assert_eq!(content(&back), SECRET, "object streams: {object_streams}");
+        assert_eq!(title(&back).as_deref(), Some("Quarterly numbers"), "object streams: {object_streams}");
+    }
+}
+
+/// A save keeps what a file is protected with: its `/Encrypt`, which holds the handler and the
+/// permissions, its `/ID`, and so its file key, under every algorithm and by either kind of save.
+#[test]
+fn a_save_keeps_the_handler_the_key_and_the_permissions() {
+    for alg in ALL {
+        let doc = Document::open_with_password(Arc::new(protect(alg, "user", "owner", -1 ^ 0b1_0000)), Some("user")).unwrap();
+        let held = |d: &Document| {
+            let encrypt = d.resolve(d.trailer().get(b"Encrypt").unwrap()).as_dict().unwrap().clone();
+            (encrypt, d.trailer().get(b"ID").cloned(), d.security().unwrap().file_key().to_vec(), format!("{:?}", d.permissions()))
+        };
+        let before = held(&doc);
+        let mut edited = doc.clone();
+        let _ = edited.add(Object::Int(1));
+        for (save, saved) in [
+            ("incremental", write_incremental(&edited, &SaveOptions::default()).unwrap()),
+            ("full", write_full(&doc, &SaveOptions::default()).unwrap()),
+        ] {
+            let back = Document::open_with_password(Arc::new(saved), Some("user")).unwrap();
+            assert!(held(&back) == before, "{alg:?}: a {save} save");
+            assert_eq!(content(&back), SECRET, "{alg:?}: a {save} save");
+        }
+    }
+}
+
+/// `/ID` has to be direct in an encrypted file, but one that isn't has its key made from the same
+/// bytes. A full save writes it direct, and an incremental one leaves it as it was.
+#[test]
+fn a_file_identifier_given_by_reference_is_read() {
+    let file = classic_file();
+    let id = hex(&file.id);
+    let reference = |entries: &str, objects: &[(u32, Vec<u8>)]| {
+        let trailer = format!("/Root {} 0 R /Encrypt {} 0 R /ID {entries}", file.root.num, file.encrypt.num);
+        updated(&file.bytes, objects, &trailer)
+    };
+    let whole = reference("900 0 R", &[(900, format!("[<{id}> <{id}>]").into_bytes())]);
+    let entries = reference("[900 0 R 901 0 R]", &[(900, format!("<{id}>").into_bytes()), (901, format!("<{id}>").into_bytes())]);
+    for file in [whole, entries] {
+        let source = Document::open(Arc::new(file)).unwrap();
+        assert_eq!(content(&source), SECRET);
+        let back = Document::open(Arc::new(write_full(&source, &SaveOptions::default()).unwrap())).unwrap();
+        assert_eq!(content(&back), SECRET);
+        assert!(matches!(back.trailer().get(b"ID"), Some(Object::Array(_))), "written direct");
+        let mut edited = source.clone();
+        let _ = edited.add(Object::Int(1));
+        let back = Document::open(Arc::new(write_incremental(&edited, &SaveOptions::default()).unwrap())).unwrap();
+        assert_eq!(content(&back), SECRET, "an incremental save");
+        assert_eq!(back.trailer().get(b"ID"), edited.trailer().get(b"ID"), "and leaves it as it was");
+    }
+}
+
+/// A direct `/Encrypt` can refer to objects. A full save dropped those it found only there, and kept
+/// its references as they were under the old numbers, so nothing in the file read afterwards.
+#[test]
+fn a_direct_encrypt_dictionary_keeps_what_it_refers_to() {
+    for object_streams in [false, true] {
+        let mut doc = Document::open(Arc::new(fixture())).unwrap();
+        doc.set_encryption(&NewEncryption {
+            algorithm: Algorithm::Aes128,
+            user_password: "",
+            owner_password: "owner",
+            permissions: -1,
+            encrypt_metadata: true,
+            seed: [9; 32],
+        })
+        .unwrap();
+        let mut dict = doc.get(doc.trailer().reference(b"Encrypt").unwrap()).as_dict().cloned().unwrap();
+        let filter = doc.add(Object::name("StdCF"));
+        let filters = doc.add(dict.get(b"CF").unwrap().clone());
+        dict.set(b"StmF".to_vec(), Object::Ref(filter));
+        dict.set(b"CF".to_vec(), Object::Ref(filters));
+        doc.trailer_mut().set(b"Encrypt".to_vec(), Object::Dict(dict));
+        let options = SaveOptions { object_streams, ..SaveOptions::default() };
+        let saved = write_full(&doc, &options).unwrap();
+        let back = Document::open(Arc::new(saved)).unwrap();
+        assert_eq!(content(&back), SECRET, "object streams: {object_streams}");
+        let again = write_full(&back, &options).unwrap();
+        assert_eq!(content(&Document::open(Arc::new(again)).unwrap()), SECRET, "object streams: {object_streams}, saved again");
+    }
+}
+
+/// How a stream is treated can be given by reference, and what that loads can be a stream too. A
+/// file can make a ladder of those, where each rung reads the rung below, then two trees wider than
+/// the object cache, which push that rung out of it, then the rung below again. Each rung would
+/// take twice what the one below does, if one read could follow any number of references.
+#[test]
+fn selectors_that_lead_to_selectors_load_at_once() {
+    let mut doc = Document::open(Arc::new(protect(Algorithm::Aes128, "", "owner", -1))).unwrap();
+    let stream_of = |doc: &mut Document, filters: Vec<Object>| {
+        let mut dict = pdfcraft_cos::Dict::new();
+        dict.set(b"Filter".to_vec(), Object::Array(filters));
+        doc.add(Object::Stream(pdfcraft_cos::Stream::from_raw(dict, Vec::new())))
+    };
+    let tree = |doc: &mut Document| {
+        let mut level: Vec<ObjRef> = (0..6_561).map(|i| doc.add(Object::Int(i))).collect();
+        while level.len() > 1 {
+            let chunks: Vec<Vec<Object>> = level.chunks(9).map(|c| c.iter().map(|r| Object::Ref(*r)).collect()).collect();
+            level = chunks.into_iter().map(|c| stream_of(doc, c)).collect();
+        }
+        Object::Ref(level[0])
+    };
+    let (first, second) = (tree(&mut doc), tree(&mut doc));
+    let mut top = doc.add(Object::Int(0));
+    // Twelve rungs of two, and the trees' five levels, stay inside the 32 that loading may nest.
+    for _ in 0..12 {
+        let (a, b) = (stream_of(&mut doc, vec![Object::Ref(top)]), stream_of(&mut doc, vec![Object::Ref(top)]));
+        top = stream_of(&mut doc, vec![Object::Ref(a), first.clone(), second.clone(), Object::Ref(b)]);
+    }
+    let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+    let (done, finished) = std::sync::mpsc::channel();
+    std::thread::spawn(move || {
+        let doc = Document::open(Arc::new(saved)).unwrap();
+        let _ = done.send(doc.get(top).as_dict().is_some());
+    });
+    // With the budget it takes milliseconds, and without it longer than anyone would wait, so a
+    // margin this wide can't fail on a busy machine.
+    assert_eq!(finished.recv_timeout(std::time::Duration::from_secs(120)), Ok(true), "loading must not fan out");
+}

crates/edit/src/images.rs

@@ -1691,6 +1691,12 @@ pub(crate) fn selectable_images(
         .collect())
 }
 
+/// Whether an XObject drawn at or after operator `from` of the page's joined operators shows
+/// inside `rect` (user space).
+pub(crate) fn painted_over(doc: &Document, page: usize, rect: [f64; 4], from: usize) -> Result<bool, EditError> {
+    Ok(page_images(doc, page)?.iter().any(|i| i.op >= from && i.visible_rect.and_then(|v| intersection(v, rect)).is_some()))
+}
+
 fn transform_image(
     doc: &mut Document,
     page: &pdfcraft_model::Page,

crates/edit/src/lib.rs

@@ -77,7 +77,7 @@ use marks::{matrix_number, n};
 pub(crate) use place::undrawable;
 #[cfg(test)]
 use place::{ISOLATION_MAX_DEPTH, OLD_WRAP_CLOSE, WRAP_CLOSE, WRAP_OPEN, is_wrap_close, page_fonts, stream_bytes, stream_tag, tagged, wrapper_role};
-use place::{check, check_on_top, contents, page_list, place_tagged};
+use place::{Reach, check, check_on_top, contents, draw_on_top, lift_on_top, page_list, place_tagged, revealed_under_paint};
 pub use place::{stamp, undrawable_message};
 
 #[cfg(test)]

crates/edit/src/place.rs

@@ -371,6 +371,76 @@ pub(crate) fn place_tagged(doc: &mut Document, page: &pdfcraft_model::Page, tag:
     Ok(mark_ref)
 }
 
+/// Draw `ops`, written for the space whose CTM is `ctm`, on top of everything on `page`, tagged
+/// `Edited`. A rewritten invisible paragraph goes here when [`revealed_under_paint`]: an OCR
+/// layer written before the scan image it lies under would keep the revealed text hidden (#3973).
+pub(crate) fn draw_on_top(doc: &mut Document, page: &pdfcraft_model::Page, ctm: [f64; 6], ops: &[pdfcraft_content::Op]) -> Result<(), EditError> {
+    if ops.is_empty() {
+        return Ok(());
+    }
+    use pdfcraft_content::Op;
+    let mut all = vec![Op::new("q", vec![]), Op::new("cm", ctm.iter().map(|v| pdfcraft_content::num(*v)).collect())];
+    all.extend_from_slice(ops);
+    all.push(Op::new("Q", vec![]));
+    place_tagged(doc, page, "Edited", pdfcraft_content::serialize_ops(&all), false).map(drop)
+}
+
+/// Where a rewritten paragraph can be drawn, in user space ([`revealed_under_paint`]).
+pub(crate) struct Reach {
+    /// The paragraph's old box, where its cover goes.
+    pub rect: [f64; 4],
+    /// The move asked for (`BlockStyle::offset`).
+    pub offset: [f64; 2],
+    /// The widest line the rewrite may draw, how many lines it has, and how far apart they are.
+    pub width: f64,
+    pub rows: usize,
+    pub pitch: f64,
+    pub upright: bool,
+}
+
+impl Reach {
+    /// The old box and the moved one, grown to `width` either way (alignment may grow a line left
+    /// or right), down to `rows` lines and up one `pitch` above its top (a larger size on the first line, however many lines the old box had); turned text grows by the lines' diagonal every way.
+    /// Unbounded when a number is not finite.
+    pub(crate) fn bounds(&self) -> [f64; 4] {
+        const UNBOUNDED: [f64; 4] = [f64::NEG_INFINITY, f64::NEG_INFINITY, f64::INFINITY, f64::INFINITY];
+        let ([dx, dy], r) = (self.offset, self.rect);
+        if !r.iter().chain(&self.offset).chain([&self.width, &self.pitch]).all(|v| v.is_finite()) {
+            return UNBOUNDED;
+        }
+        let moved = [r[0] + dx, r[1] + dy, r[2] + dx, r[3] + dy];
+        let rows = f64::from(u32::try_from(self.rows).unwrap_or(u32::MAX));
+        let (width, height) = (self.width.abs(), self.pitch.abs() * rows);
+        let grown = if self.upright {
+            [moved[0].min(moved[2] - width), moved[1].min(moved[3] - height), moved[2].max(moved[0] + width), moved[3] + self.pitch.abs()]
+        } else {
+            let d = width.hypot(height);
+            [moved[0] - d, moved[1] - d, moved[2] + d, moved[3] + d]
+        };
+        let b = [r[0].min(grown[0]), r[1].min(grown[1]), r[2].max(grown[2]), r[3].max(grown[3])];
+        if b.iter().all(|v| v.is_finite()) { b } else { UNBOUNDED }
+    }
+}
+
+/// Whether a rewritten paragraph that was `invisible` goes on top of page `page`: something after
+/// operator `at` of the page's joined `ops` paints over `reach` (user space, [`Reach::bounds`]), as the scan image
+/// does over an OCR layer written before it (#3973). XObjects count where they are drawn; an inline
+/// image or a shading after it counts anywhere, and so does any XObject when the page's images
+/// cannot be listed.
+pub(crate) fn revealed_under_paint(doc: &Document, page: usize, invisible: bool, reach: [f64; 4], ops: &[pdfcraft_content::Op], at: usize) -> bool {
+    let later = ops.get(at..).unwrap_or_default();
+    if !invisible || later.iter().any(|op| op.is("BI") || op.is("sh")) {
+        return invisible;
+    }
+    later.iter().any(|op| op.is("Do")) && crate::images::painted_over(doc, page, reach, at).unwrap_or(true)
+}
+
+/// The operators to draw on top of the page ([`draw_on_top`]): all of `paragraph` when `over`,
+/// none otherwise. The page was checked to take them ([`check_on_top`]) before the edit began.
+pub(crate) fn lift_on_top(over: bool, paragraph: &mut Vec<pdfcraft_content::Op>) -> Vec<pdfcraft_content::Op> {
+    if over { std::mem::take(paragraph) } else { Vec::new() }
+}
+
 fn too_deep_on_top() -> EditError {
     EditError::Invalid("the page's marked content is nested too deeply to add anything on top of it".into())
 }

crates/edit/src/tests.rs

@@ -6213,6 +6213,126 @@ fn group_selection_refuses_incomplete_content_and_resource_budget_overruns() {
     assert!(editable_objects(&doc, 0).is_err(), "an undecodable stream is refused");
 }
 
+/// Invisible text moves on top only when something painted after it covers it: an XObject drawn
+/// over its box (an image, or a form holding one), or any inline image or shading. An image
+/// clipped away entirely, or drawn elsewhere, does not move it.
+#[test]
+fn revealed_text_moves_on_top_only_when_painted_over() {
+    let on_top_of = |doc: Document| {
+        let block = text::text_blocks(&doc, 0).unwrap().remove(0);
+        let ops = pdfcraft_content::parse(&page_content_bytes(&doc, 0)).ops;
+        let at = ops.iter().position(|o| o.is("BT")).unwrap();
+        revealed_under_paint(&doc, 0, block.invisible, block.rect, &ops, at)
+    };
+    let on_top = |content: &str| on_top_of(image_page_with(content));
+    let scan = "q 200 0 0 100 100 100 cm /Im0 Do Q";
+    assert!(on_top(&format!("BT /F1 12 Tf 3 Tr 110 150 Td (Under) Tj ET {scan}")), "the scan covers it");
+    assert!(!on_top(&format!("BT /F1 12 Tf 3 Tr 400 600 Td (Away) Tj ET {scan}")), "an image elsewhere");
+    assert!(!on_top(&format!("{scan} BT /F1 12 Tf 3 Tr 110 150 Td (Over) Tj ET")), "the scan is drawn first");
+    assert!(!on_top(&format!("BT /F1 12 Tf 0 Tr 110 150 Td (Shown) Tj ET {scan}")), "visible text stays where it is");
+    assert!(!on_top("BT /F1 12 Tf 3 Tr 110 150 Td (Path) Tj ET 0 0 600 800 re f"), "a filled path does not move it");
+    assert!(on_top("BT /F1 12 Tf 3 Tr 400 600 Td (Shade) Tj ET /Sh sh"), "a shading after it");
+    assert!(on_top("BT /F1 12 Tf 3 Tr 400 600 Td (Inline) Tj ET BI /W 1 /H 1 /CS /G /BPC 8 ID x EI"), "an inline image after it");
+    let under = "BT /F1 12 Tf 3 Tr 110 150 Td (Under) Tj ET";
+    let elsewhere = "q 50 0 0 50 400 600 cm /Im0 Do Q";
+    assert!(!on_top(&format!("{under} q 0 0 10 10 re W n {scan} Q")), "the scan is clipped away entirely");
+    assert!(on_top(&format!("{under} {elsewhere} {scan}")), "two images, the second over it");
+    assert!(on_top(&format!("{under} {scan} {elsewhere}")), "two images, the first over it");
+    assert!(!on_top(&format!("{under} {elsewhere} {elsewhere}")), "two images, neither over it");
+    let in_form = |content: &str| {
+        let page = "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 600 800] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> /XObject << /Fm0 7 0 R >> >> >>";
+        let image = stream("/Type /XObject /Subtype /Image /Width 1 /Height 1 /ColorSpace /DeviceGray /BitsPerComponent 8", "A");
+        let form = stream("/Type /XObject /Subtype /Form /BBox [0 0 1 1] /Resources << /XObject << /Im0 6 0 R >> >>", "/Im0 Do");
+        let objs = [
+            "<< /Type /Catalog /Pages 2 0 R >>".to_string(),
+            "<< /Type /Pages /Kids [3 0 R] /Count 1 >>".into(),
+            page.into(),
+            stream("", content),
+            "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>".into(),
+            image,
+            form,
+        ];
+        on_top_of(build(&objs.iter().map(String::as_str).collect::<Vec<_>>()))
+    };
+    assert!(in_form(&format!("{under} q 200 0 0 100 100 100 cm /Fm0 Do Q")), "a form holding the scan, over it");
+    assert!(!in_form(&format!("{under} q 50 0 0 50 400 600 cm /Fm0 Do Q")), "a form holding an image elsewhere");
+}
+
+/// Revealed OCR text is checked where the rewrite lands, not only where it was: an image drawn
+/// after it over just the moved or grown text still lifts the text on top, on both rewrite paths.
+#[test]
+fn an_ocr_rewrite_goes_on_top_of_paint_over_where_it_lands() {
+    let scan = "q 200 0 0 100 100 100 cm /Im0 Do Q";
+    let moved = text::BlockStyle { offset: Some([-290.0, -450.0]), ..Default::default() };
+    let sized = text::BlockStyle { size: Some(24.0), ..Default::default() };
+    let spaced = text::BlockStyle { line_spacing: Some(3.0), ..Default::default() };
+    let range = text::RangeStyle {
+        range: 0..2,
+        family: None,
+        resource: None,
+        size: Some(120.0),
+        color: None,
+        underline: None,
+        char_spacing: None,
+        scale: None,
+    };
+    let enlarged = text::BlockStyle { ranges: vec![range], ..Default::default() };
+    let above = "q 200 0 0 60 100 200 cm /Im0 Do Q";
+    let cases = [
+        ("BT /F1 12 Tf 3 Tr 400 600 Td (Away) Tj ET", "Moved", &moved),
+        ("BT /F1 12 Tf 3 Tr 400 600 Td (Away) Tj ET", "Moved\nTwice", &moved),
+        ("BT /F1 12 Tf 3 Tr 40 150 Td (Hi) Tj ET", "Hello there, this line now runs well past the scan's left edge", &text::BlockStyle::default()),
+        ("BT /F1 12 Tf 3 Tr 40 150 Td (Hi) Tj ET", "Hello there,\nthis line now runs well past the scan's left edge", &text::BlockStyle::default()),
+        ("BT /F1 12 Tf 3 Tr 110 230 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &text::BlockStyle::default()),
+    ];
+    let low = "q 200 0 0 30 100 300 cm /Im0 Do Q";
+    let cases = cases.into_iter().map(|(c, e, s)| (c, e, s, scan)).chain([
+        ("BT /F1 12 Tf 3 Tr 110 500 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &sized, low),
+        ("BT /F1 12 Tf 3 Tr 110 500 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &spaced, low),
+        ("BT /F1 12 Tf 3 Tr 110 150 Td (Hi there) Tj ET", "Hi there", &enlarged, above),
+    ]);
+    for (content, edit, style, scan) in cases {
+        let mut doc = image_page_with(&format!("{content} {scan}"));
+        let before = text::text_blocks(&doc, 0).unwrap().remove(0);
+        let ops = pdfcraft_content::parse(&page_content_bytes(&doc, 0)).ops;
+        let at = ops.iter().position(|o| o.is("BT")).unwrap();
+        assert!(!revealed_under_paint(&doc, 0, true, before.rect, &ops, at), "{edit:?}: the old box alone is clear of the scan");
+        text::rewrite_block(&mut doc, 0, 0, Some(edit), style).unwrap();
+        let ops = pdfcraft_content::parse(&page_content_bytes(&doc, 0)).ops;
+        let scan_at = ops.iter().position(|o| o.is("Do")).unwrap();
+        let shows = ["Tj", "TJ", "'", "\""];
+        assert!(ops.iter().skip(scan_at).any(|o| shows.iter().any(|s| o.is(s))), "{edit:?}: the rewrite is drawn over the scan");
+    }
+}
+
+/// [`crate::Reach`] grows the old box to the move, the width either way and the lines below.
+#[test]
+fn a_rewrites_reach_covers_its_move_width_and_lines() {
+    let reach = |offset, width, rows, upright| crate::Reach { rect: [10.0, 90.0, 30.0, 100.0], offset, width, rows, pitch: 10.0, upright }.bounds();
+    assert_eq!(reach([0.0, 0.0], 20.0, 1, true), [10.0, 90.0, 30.0, 110.0]);
+    assert_eq!(reach([5.0, -50.0], 20.0, 1, true), [10.0, 40.0, 35.0, 100.0]);
+    assert_eq!(reach([0.0, 0.0], 50.0, 3, true), [-20.0, 70.0, 60.0, 110.0]);
+    assert_eq!(reach([0.0, 0.0], 30.0, 4, false), [-40.0, 40.0, 80.0, 150.0]);
+    assert_eq!(reach([f64::NAN, 0.0], 20.0, 1, true)[0], f64::NEG_INFINITY);
+    let larger = crate::Reach { rect: [10.0, 90.0, 30.0, 100.0], offset: [0.0, 0.0], width: 20.0, rows: 1, pitch: 24.0, upright: true };
+    assert_eq!(larger.bounds(), [10.0, 76.0, 30.0, 124.0], "a larger size grows the line up as well as down");
+}
+
+/// Revealed OCR text may have to go on top of the page; a page whose marked content nests too deep
+/// for that is refused before either rewrite path changes anything.
+#[test]
+fn an_ocr_rewrite_refused_on_top_leaves_the_document_as_it_was() {
+    let content = format!("{} BT /F1 20 Tf 3 Tr 42 44 Td (John) Tj ET /Im Do {}", "/X BMC ".repeat(10_001), "EMC ".repeat(10_001));
+    let mut doc = text_page(&content);
+    assert!(text::text_blocks(&doc, 0).unwrap()[0].invisible);
+    let before = write_full(&doc, &SaveOptions::default()).unwrap();
+    for edit in ["Jane", "Jane\nDoe"] {
+        let error = text::rewrite_block(&mut doc, 0, 0, Some(edit), &text::BlockStyle::default()).unwrap_err();
+        assert!(error.to_string().contains("nested too deeply"), "{edit:?}: {error}");
+        assert!(write_full(&doc, &SaveOptions::default()).unwrap() == before, "{edit:?}: a refused rewrite changes nothing");
+    }
+}
+
 #[test]
 fn group_move_budget_refusals_keep_the_original_page_selectable() {
     let text = text_page(&format!("{} BT /F1 12 Tf 40 400 Td (Target) Tj ET", "n ".repeat(99_995)));

crates/edit/src/text/blocks.rs

@@ -31,7 +31,8 @@ pub struct TextBlock {
     /// Byte ranges in `editor_text` and their source line indexes.
     pub spans: Vec<(std::ops::Range<usize>, usize)>,
     /// Every line is invisible text (rendering mode 3): an OCR layer over a scanned image, whose
-    /// pixels show the words. A rewrite draws the new text visibly (see [`BlockStyle::cover`]).
+    /// pixels show the words. A rewrite draws the new text visibly, on top of the page when
+    /// the scan is drawn after it (see [`BlockStyle::cover`]).
     pub invisible: bool,
 }
 

crates/edit/src/text/interp.rs

@@ -18,13 +18,33 @@ pub(super) struct TextState {
     /// graphics state the text was painted with that [`TextState::ops`] doesn't restate.
     pub(super) stroke: Vec<Op>,
     pub(super) line_width: Option<f64>,
-    ext_gstate: Vec<Vec<u8>>,
+    ext_gstate: Vec<GsSelection>,
     /// The dash pattern and line cap in force (see [`Ts`]): compared, not restated.
     pub(super) dash: Dash,
     pub(super) line_cap: i64,
 }
 
 impl TextState {
+    /// The state a page's content starts in (ISO 32000-2 §8.4.1, §9.3.1): what is in force on
+    /// top of the page, after its content wrapped in `q`/`Q`.
+    pub(crate) fn initial() -> Self {
+        TextState {
+            font: None,
+            char_spacing: 0.0,
+            word_spacing: 0.0,
+            scale: 1.0,
+            leading: 0.0,
+            rise: 0.0,
+            fill: Vec::new(),
+            render_mode: 0,
+            stroke: Vec::new(),
+            line_width: None,
+            ext_gstate: Vec::new(),
+            dash: (Vec::new(), 0.0),
+            line_cap: 0,
+        }
+    }
+
     pub(super) fn of(ts: &Ts) -> Self {
         TextState {
             font: ts.font.as_ref().map(|(n, _)| (String::from_utf8_lossy(n).into_owned(), ts.size)),
@@ -54,13 +74,17 @@ impl TextState {
     ///
     /// A `gs` has no inverse, so a selection `current` has and this state doesn't stays in force:
     /// run these inside a `q`/`Q` that starts from `current`, one per state drawn.
-    pub(crate) fn paint_ops(&self, current: &TextState) -> Vec<Op> {
+    ///
+    /// `ctm` is the CTM where they run. A soft mask is placed by the CTM its `gs` ran at
+    /// (ISO 32000-2 §11.6.5.2), so one selected at another CTM is selected there and the CTM
+    /// set back.
+    pub(crate) fn paint_ops(&self, current: &TextState, ctm: [f64; 6]) -> Vec<Op> {
         let n = pdfcraft_content::num;
         let mut v = Vec::new();
         // The selections both share stay in force; the ones after them are selected again in order.
         let shared = self.ext_gstate.iter().zip(&current.ext_gstate).take_while(|(a, b)| a == b).count();
-        for name in self.ext_gstate.iter().skip(shared) {
-            v.push(Op::new("gs", vec![Object::Name(name.clone())]));
+        for sel in self.ext_gstate.iter().skip(shared) {
+            sel.push_ops(&mut v, ctm);
         }
         // A reselected ExtGState may set `/LW`, so the width (already the effective one) follows it.
         let reselected = !v.is_empty();
@@ -222,7 +246,7 @@ pub(super) struct Ts {
     /// The line width a `w` or an ExtGState's `/LW` set (`None`: the initial 1.0).
     pub(super) line_width: Option<f64>,
     /// The ExtGState resources selected with `gs`, oldest first (see [`select_gs`]).
-    pub(super) ext_gstate: Vec<Vec<u8>>,
+    pub(super) ext_gstate: Vec<GsSelection>,
     /// The dash pattern a `d` or an ExtGState's `/D` set (initially solid: `[] 0`).
     pub(super) dash: Dash,
     /// The line cap a `J` or an ExtGState's `/LC` set (initially 0, butt).
@@ -255,12 +279,38 @@ const MAX_GS: usize = 32;
 /// Record `gs /name` in `list`. A `gs` sets every parameter its dictionary names to an absolute
 /// value, so a later selection of the same dictionary overrides the earlier one completely: the
 /// earlier entry goes, which keeps replaying the list equivalent to replaying the stream.
-fn select_gs(list: &mut Vec<Vec<u8>>, name: &[u8]) {
-    list.retain(|n| n != name);
+fn select_gs(list: &mut Vec<GsSelection>, name: &[u8], anchor: Option<[f64; 6]>) {
+    list.retain(|s| s.name != name);
     if list.len() >= MAX_GS {
         list.remove(0);
     }
-    list.push(name.to_vec());
+    list.push(GsSelection { name: name.to_vec(), anchor });
+}
+
+/// One `gs` selection: the ExtGState's resource name, and the CTM it ran at when the dictionary
+/// has a soft mask, which that CTM places (ISO 32000-2 §11.6.5.2).
+#[derive(Clone, Debug, PartialEq)]
+pub(crate) struct GsSelection {
+    name: Vec<u8>,
+    anchor: Option<[f64; 6]>,
+}
+
+impl GsSelection {
+    /// Select this ExtGState from where the CTM is `ctm`: at its anchor, then back to `ctm`. Both
+    /// moves need an invertible matrix; without one it is selected where it runs.
+    fn push_ops(&self, v: &mut Vec<Op>, ctm: [f64; 6]) {
+        let gs = Op::new("gs", vec![Object::Name(self.name.clone())]);
+        let moves = self.anchor.filter(|a| *a != ctm).and_then(|a| {
+            let (anchor, here) = (Matrix(a), Matrix(ctm));
+            Some((anchor.then(&here.invert()?), here.then(&anchor.invert()?)))
+        });
+        let Some((to, back)) = moves else {
+            v.push(gs);
+            return;
+        };
+        let cm = |m: Matrix| Op::new("cm", m.0.iter().map(|x| pdfcraft_content::num(*x)).collect());
+        v.extend([cm(to), gs, cm(back)]);
+    }
 }
 
 /// The text-showing operators of one stream with their text, font, box and baseline.
@@ -879,14 +929,15 @@ pub(super) fn interpret(
             b"Ts" => ts.rise = op.num(0).unwrap_or(0.0),
             b"Tr" => ts.render_mode = op.operands.first().and_then(Object::as_int).unwrap_or(-1),
             b"gs" => {
-                if let Some(name) = op.name(0) {
-                    select_gs(&mut ts.ext_gstate, name);
-                }
                 let mut held = None;
                 let params = match op.name(0).and_then(|name| states.get(name)) {
                     Some(p) => super::dict_in_place(doc, p, &mut held),
                     None => None,
                 };
+                if let Some(name) = op.name(0) {
+                    let masked = params.and_then(|p| p.get(b"SMask")).is_some_and(|m| doc.resolve(m).as_dict().is_some());
+                    select_gs(&mut ts.ext_gstate, name, masked.then_some(ts.ctm.0));
+                }
                 if let Some(params) = params {
                     ts.gs.apply(doc, params);
                     // `/LW` sets the line width as `w` does (ISO 32000-2 §8.4.5).

crates/edit/src/text/rewrite.rs

@@ -702,11 +702,13 @@ fn block_ops(plan: &BlockPlan<'_>, writer: &LineWriter<'_>, wrapped: &[(String,
     let mut ops = vec![Op::new("q", vec![])];
     ops.extend(reveal_ops(plan.block, plan.lines, plan.style, plan.emit.ctm)?);
     // Moved: a translation inside that state.
+    let mut ctm = Matrix(plan.emit.ctm);
     if let Some((ax, ay)) = plan.movement {
         ops.push(Op::new("cm", vec![n(1.0), n(0.0), n(0.0), n(1.0), n(ax), n(ay)]));
+        ctm = Matrix([1.0, 0.0, 0.0, 1.0, ax, ay]).then(&ctm);
     }
     // Painted as the paragraph was, including what its text object set before the first show.
-    ops.extend(plan.state.paint_ops(plan.after));
+    ops.extend(plan.state.paint_ops(plan.after, ctm.0));
     ops.push(Op::new("BT", vec![]));
     let mut state = plan.state.clone();
     state.word_spacing = 0.0;
@@ -816,6 +818,11 @@ pub(crate) fn rewrite_block_from(
     let first = members.first().copied().ok_or_else(|| EditError::Invalid("the paragraph has no source runs".into()))?;
     members.iter().try_for_each(|line| line.ensure_editable())?;
     let p = page_dict(doc, page)?;
+    // Revealed OCR text may go on top of the page (see `revealed_under_paint`): a page that can't
+    // take that is refused here, before either rewrite path changes anything.
+    if b.invisible {
+        crate::check_on_top(doc, &p)?;
+    }
     let mut res = p.dict.get(b"Resources").map(|r| doc.resolve(r)).and_then(|r| r.as_dict().cloned()).unwrap_or_default();
     let mut fonts_res = res.get(b"Font").map(|f| doc.resolve(f)).and_then(|f| f.as_dict().cloned()).unwrap_or_default();
     let dispatch = choose_rewrite_path(doc, &fonts_res, &b, &members, first, text, style)?;
@@ -930,9 +937,28 @@ pub(crate) fn rewrite_block_from(
         char_spacing: o_state.char_spacing,
         lead,
     };
-    let plan =
-        BlockPlan { block: &b, lines: &lines, style, emit, after, movement, state: o_state, tm, size, underline: style.underline == Some(true) };
+    let at = if split { start } else { emit.bt_op };
+    // Revealed OCR text that something is painted over goes on top of the page, where it starts
+    // from the initial state.
+    let widest = wrapped.iter().map(|(l, _, _)| advance.of(l)).fold(width, f64::max);
+    let reach = crate::Reach { rect: b.rect, offset: [dx, dy], width: widest, rows: wrapped.len(), pitch: lead * k, upright };
+    let over = crate::revealed_under_paint(doc, page, b.invisible, reach.bounds(), &ops, at);
+    let initial = TextState::initial();
+    let drawn_from = if over { &initial } else { after };
+    let plan = BlockPlan {
+        block: &b,
+        lines: &lines,
+        style,
+        emit,
+        after: drawn_from,
+        movement,
+        state: o_state,
+        tm,
+        size,
+        underline: style.underline == Some(true),
+    };
     let mut block_ops = block_ops(&plan, &writer, &wrapped, font.show_font.clone())?;
+    let on_top = crate::lift_on_top(over, &mut block_ops);
     let n = pdfcraft_content::num;
     block_ops.extend(after.ops().into_iter().filter(|op| !op.is("Tf") || after.font.is_some()));
     if split {
@@ -940,7 +966,6 @@ pub(crate) fn rewrite_block_from(
         block_ops.push(Op::new("BT", vec![]));
         block_ops.push(Op::new("Tm", emit.tlm.iter().map(|v| n(*v)).collect()));
     }
-    let at = if split { start } else { emit.bt_op };
     let new_data = splice(&pieces, &ops, |i| {
         let insert = if i == at { std::mem::take(&mut block_ops) } else { Vec::new() };
         (insert, !dropped.contains(&i))
@@ -957,12 +982,14 @@ pub(crate) fn rewrite_block_from(
             d.set(b"Resources".to_vec(), Object::Dict(res));
         }
     })?;
+    crate::draw_on_top(doc, &p, emit.ctm, &on_top)?;
     Ok(LineEdit { substituted: font.substituted })
 }
 
 /// The cover (when [`BlockStyle::cover`] asks for one) and visible rendering that start a
 /// rewritten invisible paragraph, drawn in the space whose CTM is `ctm`. Nothing for visible text.
-/// The paragraph's `q`/`Q` restores the rendering mode for the invisible text after it.
+/// The paragraph's `q`/`Q` restores the rendering mode for the invisible text after it; one
+/// painted over where it was is drawn on top of the page instead ([`crate::draw_on_top`]).
 pub(crate) fn reveal_ops(block: &TextBlock, lines: &[TextLine], style: &BlockStyle, ctm: [f64; 6]) -> Result<Vec<Op>, EditError> {
     if !block.invisible {
         return Ok(Vec::new());

crates/edit/src/text_regions/styled.rs

@@ -1,3 +1,4 @@
+use super::super::interp::TextState;
 use super::grouping::{across, is_centred, row_rect};
 use super::{
     BlockStyle, CraftFont, Dict, Document, EditError, HashMap, LineEdit, MAX_TYPE3_GLYPHS, Matrix, Metrics, Object, Op, PdfString, Pieces,
@@ -401,6 +402,16 @@ fn paragraph_geometry(doc: &Document, page: &pdfcraft_model::Page, block: &TextB
     Ok((dx, dy, style.width.unwrap_or(natural).clamp(1.0, 14_400.0)))
 }
 
+/// How far below a row of `size` the next one is written: the source's leading unless a size
+/// or line spacing is chosen.
+fn row_step(style: &BlockStyle, size: f64, source_leading: f64) -> f64 {
+    if style.line_spacing.is_none() && style.size.is_none() {
+        source_leading
+    } else {
+        style.line_spacing.unwrap_or(1.5).clamp(0.5, 5.0) * style.size.unwrap_or(size)
+    }
+}
+
 type WrappedStyledRows = (StyledRows, RowRanges, Vec<usize>, Vec<bool>, Vec<usize>);
 
 fn wrap_styled_rows(
@@ -976,6 +987,7 @@ pub(crate) fn rewrite_styled_block(
     let o = &lead.origin;
     // What is in force where the rewrite is drawn, and what the text after it expects.
     let after = if split { &o.state } else { &o.bt_state };
+    let at = if split { start } else { o.bt_op };
     validate_contextual_rows(&rows, &kept)?;
     let measured: Vec<_> = rows.iter().map(|row| measure(row)).collect::<Result<_, _>>()?;
     let shaped = prepare_shaped_rows(doc, &fonts, &rows, &kept, advance)?;
@@ -989,6 +1001,7 @@ pub(crate) fn rewrite_styled_block(
         .ok_or_else(|| EditError::Invalid("the paragraph is drawn in a space it cannot be edited in".into()))?;
     let (tx, ty) = back.apply(dx, dy);
     block_ops.push(Op::new("cm", vec![n(1.0), n(0.0), n(0.0), n(1.0), n(tx), n(ty)]));
+    let run_ctm = Matrix([1.0, 0.0, 0.0, 1.0, tx, ty]).then(&Matrix(o.ctm)).0;
     // A new row can land one leading above the next paragraph and look like the same
     // paragraph. When every row is in this rewrite, a paragraph marker keeps them in one
     // scope so the neighbour stays out (#2517). A row left in the source stream cannot share
@@ -1007,6 +1020,19 @@ pub(crate) fn rewrite_styled_block(
         })
         .rfind(|v| *v > 0.0)
         .unwrap_or(first.size * 1.5);
+    // Revealed OCR text that something is painted over goes on top of the page, where it starts
+    // from the initial state.
+    let largest =
+        block.lines.iter().filter_map(|i| lines.get(*i)).map(|l| l.size).chain(style.ranges.iter().filter_map(|r| r.size)).fold(first.size, f64::max);
+    // At least one line of the largest glyphs, so a larger range reaches up as far as it draws.
+    const LINE_EM: f64 = 1.2;
+    let pitch = source_leading.max(row_step(style, largest, source_leading)).max(largest * LINE_EM);
+    let widest = measured.iter().copied().fold(width, f64::max);
+    // This path lays rows out along user-space baselines, so the paragraph is upright here.
+    let reach = crate::Reach { rect: block.rect, offset: [dx, dy], width: widest, rows: rows.len(), pitch, upright: true };
+    let over = crate::revealed_under_paint(doc, page, block.invisible, reach.bounds(), &ops, at);
+    let initial = TextState::initial();
+    let drawn_from = if over { &initial } else { after };
     let mut baseline = first.origin.baseline;
     for (row_index, row) in rows.iter().enumerate() {
         let anchor = block.rows.get(row_index).and_then(|r| r.first()).and_then(|i| lines.get(*i));
@@ -1073,7 +1099,7 @@ pub(crate) fn rewrite_styled_block(
             // object (`gs`, stroke, line width, `Tr`; #3508/#3509) from the state the rewrite is
             // drawn in: a `gs` has no inverse, so one run's ExtGState would stay for the next.
             block_ops.push(Op::new("q", vec![]));
-            block_ops.extend(state.paint_ops(after));
+            block_ops.extend(state.paint_ops(drawn_from, run_ctm));
             if let Some((_, shaped, _)) = shaped_runs.get(&(row_index, pos)) {
                 let resource = glyph_resources.get(&(row_index, pos)).ok_or_else(|| EditError::Invalid("shaped font is missing".into()))?;
                 let mut properties = Dict::new();
@@ -1164,21 +1190,17 @@ pub(crate) fn rewrite_styled_block(
             x += segment_width;
             pos = end;
         }
-        baseline -= if style.line_spacing.is_none() && style.size.is_none() {
-            source_leading
-        } else {
-            style.line_spacing.unwrap_or(1.5).clamp(0.5, 5.0) * style.size.unwrap_or(anchor.size)
-        };
+        baseline -= row_step(style, anchor.size, source_leading);
     }
     push_whole_paragraph_marker(&mut block_ops, marked, "EMC");
     block_ops.push(Op::new("Q", vec![]));
+    let on_top = crate::lift_on_top(over, &mut block_ops);
     block_ops.extend(after.ops());
     if split {
         block_ops.insert(0, Op::new("ET", vec![]));
         block_ops.push(Op::new("BT", vec![]));
         block_ops.push(Op::new("Tm", o.tlm.iter().map(|v| n(*v)).collect()));
     }
-    let at = if split { start } else { o.bt_op };
     // A kept source row sits outside `block_ops`. Bound the whole paragraph when a marker is
     // safe. The close is not part of `block_ops`: that vector can end inside a text object
     // when the rewrite splits one, and a kept row's operators come later in the stream.
@@ -1190,5 +1212,6 @@ pub(crate) fn rewrite_styled_block(
         d.set(b"Contents".to_vec(), contents);
         d.set(b"Resources".to_vec(), Object::Dict(res));
     })?;
+    crate::draw_on_top(doc, &p, o.ctm, &on_top)?;
     Ok(LineEdit { substituted })
 }

crates/engine/src/edit.rs

@@ -6,7 +6,7 @@ use crate::{
     AddedContent, AddedText, Background, BoxSpec, EditError, FieldProps, FieldValue, FillMark, HeaderFooter, Hidden, ImageEdit, InitialView, Label,
     LineEnding, LinkAction, LinkStyle, MarkFile, MarkKind, Markup, NewAnnotation, NewField, NoteIcon, ObjectTarget, PageBox, Protection, ReviewState,
     Rgb, Shape, Standard, Style, TabOrder, TransitionSpec, Watermark, a11y, copy_image, decode_data_file, embed_image, field_table, fit_picture,
-    image_content_type, is_xfa_data_file, js, mark_source, measure, open_source, strip_xfa, unrestricted, xfa, xfa_after_data_change,
+    image_content_type, is_xfa_data_file, js, mark_source, measure, model_poster, open_source, strip_xfa, unrestricted, xfa, xfa_after_data_change,
 };
 
 mod labels;
@@ -119,6 +119,15 @@ pub enum Edit {
         bold: Option<bool>,
         italic: Option<bool>,
     },
+    /// Write `bookmarks` as children of `parent` from child `index` on, or with `replace` in
+    /// place of the whole outline (`parent` must then be `[]`). A bookmark whose page this
+    /// document lacks is kept without a destination (see [`pdfcraft_organize::import_outline`]).
+    ImportBookmarks {
+        parent: Vec<usize>,
+        index: usize,
+        bookmarks: Vec<pdfcraft_organize::OutlineNode>,
+        replace: bool,
+    },
     /// Bookmarks for the tagged headings (H, H1–H6), nested by level under a new first
     /// "Untitled" bookmark (New Bookmarks from Structure).
     BookmarksFromStructure,
@@ -157,6 +166,17 @@ pub enum Edit {
         file: MarkFile,
         author: String,
     },
+    /// Rich Media ▸ Add 3D: a U3D or PRC `model` as a 3D annotation in `rect` on `page`, named
+    /// `name` (its alternate description). Its poster is the picture in `poster` (a PDF page or an
+    /// image) fitted inside `rect`, keeping its shape and centred, or a labelled frame without one.
+    AddModel3d {
+        page: usize,
+        rect: [f64; 4],
+        model: Arc<Vec<u8>>,
+        poster: Option<MarkFile>,
+        activation: pdfcraft_annot::Activation3d,
+        name: String,
+    },
     /// Delete the comment at `index` in the page's `/Annots`, with its pop-up and replies.
     DeleteAnnotation {
         page: usize,

crates/engine/src/edit/labels.rs

@@ -38,6 +38,7 @@ pub const EDIT_LABELS: &[&str] = &[
     "Set bookmark destination",
     "Colour",
     "Style",
+    "Import bookmarks",
     "New bookmarks from structure",
     "New bookmarks from text styles",
     "Number pages",
@@ -68,6 +69,7 @@ pub const EDIT_LABELS: &[&str] = &[
     "Add inserted text",
     "Add file attachment",
     "Add stamp",
+    "Add 3D model",
     "Delete comment",
     "Edit comment",
     "Reply",
@@ -193,6 +195,7 @@ impl Edit {
             // The bookmark Style and Colour menus' own names, already said in every language.
             Edit::SetBookmarkColor { .. } => Label::of("Colour"),
             Edit::SetBookmarkStyle { .. } => Label::of("Style"),
+            Edit::ImportBookmarks { .. } => Label::of("Import bookmarks"),
             Edit::BookmarksFromStructure => Label::of("New bookmarks from structure"),
             Edit::BookmarksFromTextStyles { .. } => Label::of("New bookmarks from text styles"),
             Edit::NumberPages { .. } => Label::of("Number pages"),
@@ -205,6 +208,7 @@ impl Edit {
             Edit::SetMeasurementScale { .. } => Label::of("Set measurement scale"),
             Edit::AddAnnotation(a) => Label::of(add_annotation(&a.shape)),
             Edit::AddCustomStamp { .. } => Label::of("Add stamp"),
+            Edit::AddModel3d { .. } => Label::of("Add 3D model"),
             Edit::DeleteAnnotation { .. } => Label::of("Delete comment"),
             Edit::SetAnnotationContents { .. } => Label::of("Edit comment"),
             Edit::ReplyToAnnotation { .. } => Label::of("Reply"),

crates/engine/src/edit/run.rs

@@ -1,6 +1,6 @@
 use super::{
     AddedContent, Arc, Edit, EditError, FieldValue, ImageEdit, NewAnnotation, Shape, a11y, copy_image, decode_data_file, embed_image, fit_picture,
-    image_content_type, is_xfa_data_file, js, mark_source, measure, open_source, strip_xfa, unrestricted, xfa, xfa_after_data_change,
+    image_content_type, is_xfa_data_file, js, mark_source, measure, model_poster, open_source, strip_xfa, unrestricted, xfa, xfa_after_data_change,
 };
 use crate::SourceProblem;
 use crate::sources::{comment_source, import_pdf_comments};
@@ -27,6 +27,7 @@ pub(crate) fn check_permission(edit: &Edit, p: &pdfcraft_cos::Permissions) -> Re
         | Edit::SetBookmarkPage { .. }
         | Edit::SetBookmarkColor { .. }
         | Edit::SetBookmarkStyle { .. }
+        | Edit::ImportBookmarks { .. }
         | Edit::BookmarksFromStructure
         | Edit::NumberPages { .. } => {
             if p.assemble() {
@@ -49,6 +50,7 @@ pub(crate) fn check_permission(edit: &Edit, p: &pdfcraft_cos::Permissions) -> Re
         Edit::AddMeasurement(_)
         | Edit::AddAnnotation(_)
         | Edit::AddCustomStamp { .. }
+        | Edit::AddModel3d { .. }
         | Edit::DeleteAnnotation { .. }
         | Edit::SetAnnotationContents { .. }
         | Edit::ReplyToAnnotation { .. }
@@ -454,6 +456,9 @@ pub(crate) fn run_edit(doc: &mut pdfcraft_cos::Document, edit: &Edit, cx: &mut E
         Edit::SetBookmarkPage { path, page } => pdfcraft_organize::set_bookmark_page(doc, path, *page)?,
         Edit::SetBookmarkColor { path, color } => pdfcraft_organize::set_bookmark_color(doc, path, *color)?,
         Edit::SetBookmarkStyle { path, bold, italic } => pdfcraft_organize::set_bookmark_style(doc, path, *bold, *italic)?,
+        Edit::ImportBookmarks { parent, index, bookmarks, replace } => {
+            pdfcraft_organize::import_outline(doc, parent, *index, bookmarks, *replace)?;
+        }
         Edit::BookmarksFromStructure => {
             let entries: Vec<_> = pdfcraft_a11y::headings(doc)
                 .into_iter()
@@ -509,6 +514,16 @@ pub(crate) fn run_edit(doc: &mut pdfcraft_cos::Document, edit: &Edit, cx: &mut E
             let index = pdfcraft_annot::add_annotation(doc, &new, &cx.meta())?;
             pdfcraft_annot::orient_image_stamp(doc, *page, index, rotation)?;
         }
+        Edit::AddModel3d { page, rect, model, poster, activation, name } => {
+            // A file that is not a model is refused before its poster is brought in.
+            pdfcraft_annot::check_model(model)?;
+            let poster = match poster {
+                Some(file) => Some(model_poster(doc, *rect, file)?),
+                None => None,
+            };
+            let new = pdfcraft_annot::NewModel3d { page: *page, rect: *rect, model, activation: *activation, poster, contents: name };
+            pdfcraft_annot::add_3d_model(doc, &new, &cx.meta())?;
+        }
         Edit::DeleteAnnotation { page, index } => pdfcraft_annot::delete_annotation(doc, *page, *index)?,
         Edit::SetAnnotationContents { page, index, text } => pdfcraft_annot::set_contents(doc, *page, *index, text, &cx.meta())?,
         Edit::ReplyToAnnotation { page, index, text, author } => {

crates/engine/src/history.rs

@@ -54,6 +54,7 @@ pub(crate) fn scope_of(edit: &Edit) -> Scope {
         Edit::AddMeasurement(_)
         | Edit::AddAnnotation(_)
         | Edit::AddCustomStamp { .. }
+        | Edit::AddModel3d { .. }
         | Edit::DeleteAnnotation { .. }
         | Edit::SetAnnotationContents { .. }
         | Edit::ReplyToAnnotation { .. }

crates/engine/src/lib.rs

@@ -72,7 +72,10 @@ pub use signature_scan::{PhotoRect, ScanError, SignaturePhoto, Turn};
 pub use stamp_preview::{CommentLayer, StampPreview};
 pub use text_preview::{TextEditPreview, UnmarkedPages};
 
-pub use pdfcraft_organize::{BoxSpec, FieldConflicts, PageBox, SplitBy, Transition, TransitionSpec, mime_for_name, split_ranges};
+pub use pdfcraft_organize::{
+    BoxSpec, FieldConflicts, MAX_IMPORT_BOOKMARKS, OutlineNode, OutlineTree, PageBox, SplitBy, Transition, TransitionSpec, mime_for_name,
+    split_ranges, unmapped as outline_unmapped, view_arity as outline_view_arity,
+};
 
 pub use pdfcraft_organize::LabelStyle;
 pub use pdfcraft_organize::Standard;
@@ -109,9 +112,10 @@ pub use pdfcraft_fonts::{MAX_SIGNATURE_CHARS, ScriptOutline, script_missing, scr
 pub use pdfcraft_annot::appearance as annot_text;
 pub use pdfcraft_annot::links::{Highlight as LinkHighlight, LinkAction, LinkItem, LinkStyle};
 pub use pdfcraft_annot::{
-    AppearanceCache, AttachIcon, FillMark, LineEnding, Markup, NOTE_SIZE, NewAnnotation, NoteIcon, OverlayFont, OverlayLook, Props as CommentProps,
-    ReviewState, Rgb, Shape, StampGroup, StampKind, Style, rect_quad,
+    Activation3d, AppearanceCache, AttachIcon, FillMark, LineEnding, Markup, NOTE_SIZE, NewAnnotation, NoteIcon, OverlayFont, OverlayLook,
+    Props as CommentProps, ReviewState, Rgb, Shape, StampGroup, StampKind, Style, rect_quad,
 };
+pub use pdfcraft_annot::{MAX_MODEL_BYTES as MAX_3D_MODEL_BYTES, ModelFormat as Model3dFormat};
 pub use pdfcraft_forms::detect;
 pub use pdfcraft_optimize as optimize;
 pub use pdfcraft_preflight as pdfa;
@@ -141,7 +145,7 @@ use layers::{apply_layer_state, set_default_layer_state, use_layer_choices};
 pub use open::{OpenContext, PreparedDocument};
 pub use page_filter::{PageOrientation, PageParity, filter_pages};
 pub use pictures::{MarkFile, image_dimensions};
-use pictures::{embed_image, fit_picture, mark_source};
+use pictures::{embed_image, fit_picture, mark_source, model_poster};
 use protection::unrestricted;
 pub use protection::{Changes, Printing, Protection, SecuritySummary};
 pub use session::Session;

crates/engine/src/pictures.rs

@@ -60,6 +60,18 @@ pub(crate) fn mark_source(doc: &mut pdfcraft_cos::Document, f: &MarkFile) -> Res
     }
 }
 
+/// A 3D model's poster: the picture in `file` brought into `doc` and fitted inside `rect`
+/// (user space), keeping its shape, and centred. It is drawn in user space and not counter-rotated
+/// (unlike a stamp), so on a page with `/Rotate` it turns with the page, as the model does.
+pub(crate) fn model_poster(doc: &mut pdfcraft_cos::Document, rect: [f64; 4], file: &MarkFile) -> Result<pdfcraft_annot::PosterPicture, EditError> {
+    let src = mark_source(doc, file)?;
+    let (sw, sh) = src.size;
+    if !(sw.is_finite() && sh.is_finite() && sw > 0.0 && sh > 0.0) {
+        return Err(EditError::Source(format!("{}: the poster has no area", file.name)));
+    }
+    Ok(pdfcraft_annot::PosterPicture { xobject: src.xobject, image: src.image, size: (sw, sh), at: fit_picture(rect, sw, sh) })
+}
+
 /// The dimensions of an image from its bytes (JPEG, PNG, TIFF), without decoding the full raster.
 pub fn image_dimensions(bytes: &[u8]) -> Option<(u32, u32)> {
     let format = image::guess_format(bytes).ok()?;

crates/engine/src/session/view.rs

@@ -168,6 +168,14 @@ impl Session {
         Some(BookmarkPage { rows, next: (end < all.len()).then_some(end), truncated: doc.info.outline_more })
     }
 
+    /// The bookmark at `path` with everything under it, or the whole outline for `[]`, as a tree
+    /// another document can take ([`crate::Edit::ImportBookmarks`]). `None` when no document has
+    /// `id`, or its structure could not be read for editing.
+    pub fn outline_tree(&self, id: DocId, path: &[usize]) -> Option<Result<pdfcraft_organize::OutlineTree, pdfcraft_organize::OutlineError>> {
+        let editor = self.get(id)?.editor.as_ref()?;
+        Some(pdfcraft_organize::outline_tree(&editor.cos, path))
+    }
+
     /// Top-level bookmarks as split points: (first page of each part, its bookmark's title).
     pub fn bookmark_splits(&self, id: DocId) -> Vec<(usize, String)> {
         let Some(doc) = self.get(id) else { return Vec::new() };

crates/engine/src/tests.rs

@@ -549,6 +549,85 @@ fn pdf_page_stamps_fit_inside_an_explicit_box() {
     assert!(content.contains("/Pic Do") && !content.contains("BI"), "{content}");
 }
 
+/// #1297: a 3D model on a page keeps the whole box as its rectangle and draws a PDF poster as a
+/// form XObject fitted inside it, keeping its shape and centred.
+#[test]
+fn a_3d_model_gets_a_fitted_vector_poster_and_a_file_that_is_not_one_is_refused() {
+    let mut session = Session::new().with_clock(|| 1_700_000_000);
+    let blank = session.create_blank(595.0, 842.0, 1).unwrap();
+    let id = session.open_new("model.pdf", blank).unwrap();
+    let mut prc = b"PRC".to_vec();
+    prc.extend_from_slice(&[1; 64]);
+    let add = |model: Vec<u8>| Edit::AddModel3d {
+        page: 0,
+        rect: [56.0, 400.0, 539.0, 700.0],
+        model: Arc::new(model),
+        poster: Some(MarkFile { name: "poster.pdf".into(), bytes: Arc::new(half_red_page()), page: 0 }),
+        activation: Activation3d::default(),
+        name: "Bracket".into(),
+    };
+    assert!(session.apply(id, add(b"%PDF-1.7 not a model".to_vec())).is_err());
+    session.apply(id, add(prc)).unwrap();
+
+    let doc = pdfcraft_cos::Document::open(session.save_bytes(id).unwrap()).unwrap();
+    let page = &pdfcraft_model::pages(&doc)[0];
+    let annots = doc.resolve(page.dict.get(b"Annots").unwrap());
+    let [only] = annots.as_array().unwrap().as_slice() else { panic!("the refused model added nothing: {annots:?}") };
+    let annot = doc.get(only.as_ref().unwrap());
+    let annot = annot.as_dict().unwrap();
+    assert_eq!(annot.name(b"Subtype"), Some(&b"3D"[..]));
+    let rect: Vec<f64> = annot.get(b"Rect").unwrap().as_array().unwrap().iter().filter_map(pdfcraft_cos::Object::as_f64).collect();
+    assert_eq!(rect, [56.0, 400.0, 539.0, 700.0], "the whole box, not the fitted picture");
+    assert_eq!(doc.resolve(annot.get(b"3DA").unwrap()).as_dict().unwrap().name(b"A"), Some(&b"XA"[..]));
+    let ap = doc.resolve(annot.get(b"AP").unwrap());
+    let pdfcraft_cos::Object::Stream(normal) = doc.get(ap.as_dict().unwrap().reference(b"N").unwrap()).as_ref().clone() else {
+        panic!("an appearance stream")
+    };
+    let pic = doc.resolve(normal.dict.get(b"Resources").unwrap()).as_dict().unwrap().clone();
+    let pic = doc.resolve(pic.get(b"XObject").unwrap()).as_dict().unwrap().reference(b"Pic").unwrap();
+    let pdfcraft_cos::Object::Stream(picture) = doc.get(pic).as_ref().clone() else { panic!("the picture is a stream") };
+    assert_eq!(picture.dict.name(b"Subtype"), Some(&b"Form"[..]), "the page is kept as a form XObject");
+    // The 80 × 40 page in the 483 × 300 box: 483 × 241.5 from y 429.25.
+    let content = String::from_utf8(normal.decoded().unwrap().to_vec()).unwrap();
+    assert!(content.contains(" 56 429.25 cm /Pic Do"), "{content}");
+}
+
+/// A PDF poster whose page has no area is refused rather than drawn as nothing.
+#[test]
+fn a_3d_poster_page_without_area_is_refused() {
+    let mut session = Session::new().with_clock(|| 1_700_000_000);
+    let blank = session.create_blank(595.0, 842.0, 1).unwrap();
+    let id = session.open_new("model.pdf", blank).unwrap();
+    let flat = String::from_utf8(half_red_page()).unwrap().replace("[0 0 80 40]", "[0 0 80 0 ]");
+    let add = Edit::AddModel3d {
+        page: 0,
+        rect: [56.0, 400.0, 539.0, 700.0],
+        model: Arc::new(b"PRC rest".to_vec()),
+        poster: Some(MarkFile { name: "flat.pdf".into(), bytes: Arc::new(flat.into_bytes()), page: 0 }),
+        activation: Activation3d::default(),
+        name: "Bracket".into(),
+    };
+    assert!(matches!(session.apply(id, add), Err(EditError::Source(_))));
+    assert!(session.get(id).unwrap().info.annotations.is_empty(), "nothing was added");
+}
+
+/// Adding a 3D model is a comment change: refused without the comments permission, and only the
+/// comments are rebuilt after it.
+#[test]
+fn a_3d_model_needs_the_comments_permission_and_changes_the_comments() {
+    let edit = Edit::AddModel3d {
+        page: 0,
+        rect: [0.0, 0.0, 100.0, 100.0],
+        model: Arc::new(b"PRC rest".to_vec()),
+        poster: None,
+        activation: Activation3d::default(),
+        name: String::new(),
+    };
+    let p = pdfcraft_cos::Permissions { bits: 0, owner: false };
+    assert_eq!(check_permission(&edit, &p), Err(EditError::NotPermitted("comments")));
+    assert_eq!(crate::history::scope_of(&edit), crate::history::Scope::Comments);
+}
+
 fn page_texts(s: &Session, id: DocId) -> Vec<String> {
     let doc = s.get(id).unwrap();
     let config = pdfcraft_render::RenderConfig { password: doc.password.as_deref().map(Arc::from), ..Default::default() };
@@ -10252,6 +10331,107 @@ fn image_transform_engine_refuses_singular_matrices_without_mutation() {
     }
 }
 
+/// Optimize has JBIG2 images share a symbol dictionary only where redaction can store each again
+/// without it. Of four pages of the same scan, the two in DeviceGray and the image mask share one;
+/// the one in a DeviceN of one colourant, which redaction doesn't store again, is coded alone.
+/// Redacting the first page then stores the second and the mask again without the dictionary,
+/// which leaves the file.
+#[test]
+fn redacting_an_optimized_jbig2_page_stores_the_rest_of_its_group_again() {
+    use pdfcraft_cos::{Dict, Document, ObjRef, Object, SaveOptions, Stream, write_full};
+    let (w, h) = (600usize, 480usize);
+    // Lines of 26 letters, each 32 rows of a run from a stem down its left side, of 2 to 24 pixels,
+    // the same to the pixel wherever it is, picked and spaced at random.
+    let mut seed = 0x2545_F491_4F6C_DD1Du64;
+    let mut next = move || {
+        seed ^= seed << 13;
+        seed ^= seed >> 7;
+        seed ^= seed << 17;
+        seed as usize
+    };
+    let letters: Vec<Vec<usize>> = (0..26).map(|_| (0..16).map(|_| 1 + next() % 12).collect()).collect();
+    let stride = w.div_ceil(8);
+    let mut bits = vec![0xFFu8; stride * h];
+    for top in (8..h - 40).step_by(44) {
+        let mut x = 8 + next() % 8;
+        while x + 32 < w {
+            let letter = &letters[next() % 26];
+            for (row, run) in letter.iter().enumerate() {
+                for (px, py) in (x..x + 2 * run).flat_map(|px| [(px, top + 2 * row), (px, top + 2 * row + 1)]) {
+                    bits[py * stride + px / 8] &= !(0x80 >> (px % 8));
+                }
+            }
+            x += 2 * letter.iter().max().unwrap_or(&1) + 4 + next() % 5;
+        }
+    }
+    let mut doc = Document::new_empty();
+    let pages = doc.root().and_then(|r| doc.get(r).as_dict().and_then(|d| d.reference(b"Pages"))).unwrap();
+    let device_n = Object::Array(vec![Object::name("DeviceN"), Object::Array(vec![Object::name("Black")]), Object::name("DeviceGray"), {
+        let mut tint = Dict::new();
+        tint.set(b"FunctionType".to_vec(), Object::Int(2));
+        tint.set(b"Domain".to_vec(), Object::Array(vec![Object::Int(0), Object::Int(1)]));
+        tint.set(b"N".to_vec(), Object::Int(1));
+        Object::Dict(tint)
+    }]);
+    let mut images: Vec<ObjRef> = Vec::new();
+    let grey = || ("ColorSpace", Object::name("DeviceGray"));
+    for (k, (key, value)) in [grey(), grey(), ("ColorSpace", device_n), ("ImageMask", Object::Bool(true))].into_iter().enumerate() {
+        let mut d = Dict::new();
+        d.set(b"Type".to_vec(), Object::name("XObject"));
+        d.set(b"Subtype".to_vec(), Object::name("Image"));
+        d.set(b"Width".to_vec(), Object::Int(w as i64));
+        d.set(b"Height".to_vec(), Object::Int(h as i64));
+        d.set(b"BitsPerComponent".to_vec(), Object::Int(1));
+        d.set(key.as_bytes().to_vec(), value);
+        let image = doc.add(Object::Stream(Stream::flate(d, &bits)));
+        images.push(image);
+        let content = doc.add(Object::Stream(Stream::from_raw(Dict::new(), b"q 144 0 0 115.2 36 600 cm /Im Do Q".to_vec())));
+        let mut xobjects = Dict::new();
+        xobjects.set(b"Im".to_vec(), Object::Ref(image));
+        let mut resources = Dict::new();
+        resources.set(b"XObject".to_vec(), Object::Dict(xobjects));
+        let mut page = Dict::new();
+        page.set(b"Type".to_vec(), Object::name("Page"));
+        page.set(b"Parent".to_vec(), Object::Ref(pages));
+        page.set(b"MediaBox".to_vec(), Object::Array(vec![0.into(), 0.into(), 612.into(), 792.into()]));
+        page.set(b"Resources".to_vec(), Object::Dict(resources));
+        page.set(b"Contents".to_vec(), Object::Ref(content));
+        if k == 0 {
+            let mut mark = Dict::new();
+            mark.set(b"Type".to_vec(), Object::name("Annot"));
+            mark.set(b"Subtype".to_vec(), Object::name("Redact"));
+            mark.set(b"Rect".to_vec(), Object::Array(vec![40.into(), 610.into(), 100.into(), 650.into()]));
+            let mark = doc.add(Object::Dict(mark));
+            page.set(b"Annots".to_vec(), Object::Array(vec![Object::Ref(mark)]));
+        }
+        let page = doc.add(Object::Dict(page));
+        doc.update_dict(pages, |d| {
+            let mut kids = d.get(b"Kids").and_then(|k| k.as_array().cloned()).unwrap_or_default();
+            kids.push(Object::Ref(page));
+            d.set(b"Count".to_vec(), Object::Int(kids.len() as i64));
+            d.set(b"Kids".to_vec(), Object::Array(kids));
+        })
+        .unwrap();
+    }
+    let mono = pdfcraft_optimize::MonoSettings {
+        compression: pdfcraft_optimize::MonoCompression::Jbig2,
+        downsample: false,
+        ..pdfcraft_optimize::MonoSettings::REDUCE
+    };
+    pdfcraft_optimize::optimize(&mut doc, &pdfcraft_optimize::Settings { mono, ..Default::default() }).unwrap();
+    let globals = |doc: &Document, image: ObjRef| match &*doc.get(image) {
+        Object::Stream(s) => s.dict.get(b"DecodeParms").and_then(Object::as_dict).and_then(|d| d.reference(b"JBIG2Globals")),
+        _ => None,
+    };
+    let shared = globals(&doc, images[0]);
+    assert!(shared.is_some() && globals(&doc, images[1]) == shared && globals(&doc, images[3]) == shared, "DeviceGray and the mask share");
+    assert_eq!(globals(&doc, images[2]), None, "the DeviceN page is coded alone");
+    pdfcraft_redact::apply(&mut doc, None).unwrap();
+    let saved = Document::open(Arc::new(write_full(&doc, &SaveOptions::default()).unwrap())).unwrap();
+    let named = saved.scan_objects().filter(|(_, o)| matches!(&**o, Object::Stream(s) if saved.jbig2_globals_ref(s).is_some())).count();
+    assert_eq!(named, 0, "no image names the dictionary, which left with them");
+}
+
 #[test]
 fn fill_sign_multiline_text_survives_engine_save_reopen_and_render() {
     let (mut session, id) = rotated_blank(0);
@@ -10268,3 +10448,35 @@ fn fill_sign_multiline_text_survives_engine_save_reopen_and_render() {
     assert_eq!(reopened.get(again).unwrap().info.annotations[0].contents.as_deref(), Some(text), "reopening preserves all blank lines");
     assert_eq!(before.rgba, render_page(&reopened, again).rgba, "the saved appearance is identical");
 }
+
+/// A whole tree goes in as one undoable step, and a refused tree changes nothing.
+#[test]
+fn imported_bookmarks_undo_in_one_step() {
+    let (mut s, id) = session_with(2);
+    let node = |title: &str, page, children| pdfcraft_organize::OutlineNode {
+        title: title.into(),
+        page,
+        view: None,
+        color: None,
+        italic: false,
+        bold: false,
+        open: true,
+        children,
+    };
+    let bookmarks = vec![node("Intro", Some(0), vec![node("Detail", Some(5), vec![])]), node("End", Some(1), vec![])];
+    s.apply(id, Edit::ImportBookmarks { parent: vec![], index: 0, bookmarks: bookmarks.clone(), replace: false }).unwrap();
+    assert_eq!(outline_titles(&s.get(id).unwrap().info.outline), ["Intro→1[Detail→0]", "End→2"]);
+    assert_eq!(s.get(id).unwrap().can_undo(), Some("Import bookmarks"));
+    assert_eq!(s.outline_tree(id, &[]).unwrap().unwrap().nodes[0].title, "Intro");
+    s.undo(id).unwrap();
+    assert!(s.get(id).unwrap().info.outline.is_empty());
+    s.apply(id, Edit::ImportBookmarks { parent: vec![], index: 0, bookmarks: bookmarks.clone(), replace: false }).unwrap();
+    s.apply(id, Edit::ImportBookmarks { parent: vec![], index: 0, bookmarks: vec![node("New", Some(1), vec![])], replace: true }).unwrap();
+    assert_eq!(outline_titles(&s.get(id).unwrap().info.outline), ["New→2"]);
+    s.undo(id).unwrap();
+    assert_eq!(outline_titles(&s.get(id).unwrap().info.outline), ["Intro→1[Detail→0]", "End→2"]);
+    s.undo(id).unwrap();
+    let err = s.apply(id, Edit::ImportBookmarks { parent: vec![4], index: 0, bookmarks, replace: false }).unwrap_err();
+    assert!(err.to_string().contains("no bookmark"), "{err}");
+    assert!(s.get(id).unwrap().info.outline.is_empty());
+}

crates/engine/tests/it/ocr_edit.rs

@@ -207,3 +207,192 @@ fn visible_stretched_text_rewrites_unchanged() {
     let i = ((y * out.width + x) * 4) as usize;
     assert_eq!(&out.rgba[i..i + 3], &[255, 255, 255]);
 }
+
+/// A scan whose OCR layer is drawn first and the opaque page image over it, as some OCR tools
+/// write it (#3973): invisible Helvetica `text` on the scanned word, then the image.
+fn ocr_under_scan(text: &str) -> std::sync::Arc<Vec<u8>> {
+    under_scan(&format!("BT /F1 20 Tf 3 Tr 42 44 Td ({text}) Tj ET"))
+}
+
+/// A page whose `text` content is followed by the opaque 200 × 100 scan image.
+fn under_scan(text: &str) -> std::sync::Arc<Vec<u8>> {
+    under_scan_with(text, |_| pdfcraft_cos::Dict::new())
+}
+
+/// As [`under_scan`], with the page's ExtGState resources made by `ext_gstates`.
+fn under_scan_with(text: &str, ext_gstates: impl FnOnce(&mut pdfcraft_cos::Document) -> pdfcraft_cos::Dict) -> std::sync::Arc<Vec<u8>> {
+    use pdfcraft_cos::{Dict, Document, Object, SaveOptions, Stream};
+    let (w, h) = (200u32, 100u32);
+    let mut rgb = Vec::new();
+    for y in 0..h {
+        for x in 0..w {
+            let ink = (WORD[0]..WORD[2]).contains(&x) && (WORD[1]..WORD[3]).contains(&y);
+            rgb.extend(if ink { INK } else { PAPER });
+        }
+    }
+    let mut d = Document::new_empty();
+    let pages = d.add(Object::Dict(Dict::new()));
+    let content = format!("{text} q 200 0 0 100 0 0 cm /Im Do Q");
+    let contents = d.add(Object::Stream(Stream::flate(Dict::new(), content.as_bytes())));
+    let mut image = Dict::new();
+    image.set(b"Type".to_vec(), Object::name("XObject"));
+    image.set(b"Subtype".to_vec(), Object::name("Image"));
+    image.set(b"Width".to_vec(), Object::Int(i64::from(w)));
+    image.set(b"Height".to_vec(), Object::Int(i64::from(h)));
+    image.set(b"ColorSpace".to_vec(), Object::name("DeviceRGB"));
+    image.set(b"BitsPerComponent".to_vec(), Object::Int(8));
+    let image = d.add(Object::Stream(Stream::flate(image, &rgb)));
+    let mut font = Dict::new();
+    font.set(b"Type".to_vec(), Object::name("Font"));
+    font.set(b"Subtype".to_vec(), Object::name("Type1"));
+    font.set(b"BaseFont".to_vec(), Object::name("Helvetica"));
+    let mut fonts = Dict::new();
+    fonts.set(b"F1".to_vec(), Object::Dict(font));
+    let mut xobjects = Dict::new();
+    xobjects.set(b"Im".to_vec(), Object::Ref(image));
+    let mut res = Dict::new();
+    res.set(b"Font".to_vec(), Object::Dict(fonts));
+    res.set(b"XObject".to_vec(), Object::Dict(xobjects));
+    res.set(b"ExtGState".to_vec(), Object::Dict(ext_gstates(&mut d)));
+    let mut p = Dict::new();
+    p.set(b"Type".to_vec(), Object::name("Page"));
+    p.set(b"Parent".to_vec(), Object::Ref(pages));
+    p.set(b"Contents".to_vec(), Object::Ref(contents));
+    p.set(b"Resources".to_vec(), Object::Dict(res));
+    p.set(b"MediaBox".to_vec(), Object::Array([0, 0, 200, 100].map(Object::Int).to_vec()));
+    let page = d.add(Object::Dict(p));
+    d.update_dict(pages, |p| {
+        p.set(b"Type".to_vec(), Object::name("Pages"));
+        p.set(b"Kids".to_vec(), Object::Array(vec![Object::Ref(page)]));
+        p.set(b"Count".to_vec(), Object::Int(1));
+    })
+    .unwrap();
+    let mut root = Dict::new();
+    root.set(b"Type".to_vec(), Object::name("Catalog"));
+    root.set(b"Pages".to_vec(), Object::Ref(pages));
+    let root = d.add(Object::Dict(root));
+    d.trailer_mut().set(b"Root".to_vec(), Object::Ref(root));
+    std::sync::Arc::new(pdfcraft_cos::write_full(&d, &SaveOptions::default()).unwrap())
+}
+
+/// The scanned word's box shows the cover and new ink, not the scan.
+fn assert_edit_shows(s: &Session, id: pdfcraft_engine::DocId, label: &str) {
+    let px = word_pixels(s, id);
+    let paper = px.iter().filter(|p| near(**p, PAPER)).count();
+    let ink = px.iter().filter(|p| near(**p, INK)).count();
+    assert!(paper * 10 > px.len() * 4, "{label}: the cover is drawn over the scan: {paper} of {} paper", px.len());
+    assert!(ink * 100 > px.len() * 3, "{label}: the new text shows: {ink} of {} ink", px.len());
+}
+
+fn texts(s: &Session, id: pdfcraft_engine::DocId) -> Vec<String> {
+    s.get(id).unwrap().text_blocks(0).iter().map(|b| b.text.replace('\n', " ")).collect()
+}
+
+fn edit_block(s: &mut Session, id: pdfcraft_engine::DocId, block: usize, text: &str) {
+    s.apply(id, Edit::EditTextBlock { page: 0, block, text: text.into(), style: Default::default() }).unwrap();
+}
+
+/// The OCR layer is under the scan image: the rewritten paragraph is drawn on top of the image,
+/// not in the OCR text's place where the image would hide it (#3973). One line takes the
+/// single-style rewrite, a typed line break the styled one. Undo restores the hidden layer, and
+/// the edit survives redo, a save and reopen, and being edited again.
+#[test]
+fn an_ocr_layer_under_the_scan_image_shows_its_edit() {
+    for edit in ["Jane", "Jane\nDoe"] {
+        let mut s = Session::new();
+        let id = s.open("ocr-under-scan.pdf", None, ocr_under_scan("John"), None).unwrap();
+        let blocks = s.get(id).unwrap().text_blocks(0);
+        assert_eq!(blocks.len(), 1);
+        assert!(blocks[0].invisible, "the OCR layer is invisible text");
+        assert!(word_pixels(&s, id).iter().all(|p| near(*p, INK)), "the scanned word fills its box");
+
+        edit_block(&mut s, id, 0, edit);
+        assert_eq!(texts(&s, id), [edit.replace('\n', " ")], "{edit:?}");
+        assert_edit_shows(&s, id, edit);
+
+        s.undo(id).unwrap();
+        assert_eq!(texts(&s, id), ["John"], "{edit:?}: undo");
+        assert!(s.get(id).unwrap().text_blocks(0)[0].invisible, "{edit:?}: undo hides the layer again");
+        assert!(word_pixels(&s, id).iter().all(|p| near(*p, INK)), "{edit:?}: undo shows the scan again");
+        s.redo(id).unwrap();
+        assert_edit_shows(&s, id, &format!("{edit:?} redo"));
+
+        let saved = s.save_bytes(id).unwrap();
+        let mut reopened = Session::new();
+        let id = reopened.open("saved.pdf", None, saved, None).unwrap();
+        assert_eq!(texts(&reopened, id), [edit.replace('\n', " ")], "{edit:?}: reopened");
+        assert_edit_shows(&reopened, id, &format!("{edit:?} reopened"));
+
+        edit_block(&mut reopened, id, 0, "Ann");
+        assert_eq!(texts(&reopened, id), ["Ann"], "{edit:?}: edited again");
+        assert_edit_shows(&reopened, id, &format!("{edit:?} edited again"));
+    }
+}
+
+/// Visible text earlier in the same text object makes the rewrite split it; the OCR phrase still
+/// goes on top of the scan, and the visible text stays.
+#[test]
+fn an_ocr_phrase_split_from_visible_text_under_the_scan_shows_its_edit() {
+    for edit in ["Jane", "Jane\nDoe"] {
+        let mut s = Session::new();
+        let page = under_scan("BT /F1 20 Tf 10 80 Td (Head) Tj 3 Tr 32 -36 Td (John) Tj ET");
+        let id = s.open("split.pdf", None, page, None).unwrap();
+        let blocks = s.get(id).unwrap().text_blocks(0);
+        let john = blocks.iter().position(|b| b.text == "John").unwrap();
+        assert!(blocks[john].invisible && blocks.iter().any(|b| b.text == "Head" && !b.invisible), "{blocks:?}");
+        edit_block(&mut s, id, john, edit);
+        let mut after = texts(&s, id);
+        after.sort();
+        let mut want = vec!["Head".to_string(), edit.replace('\n', " ")];
+        want.sort();
+        assert_eq!(after, want, "{edit:?}");
+        assert_edit_shows(&s, id, &format!("{edit:?} split"));
+    }
+}
+
+/// `/SM`: a luminosity soft mask that is white over 30..110 × 30..70 in the space it is selected
+/// in, black elsewhere.
+fn soft_mask_state(d: &mut pdfcraft_cos::Document) -> pdfcraft_cos::Dict {
+    use pdfcraft_cos::{Dict, Object, Stream};
+    let mut group = Dict::new();
+    group.set(b"S".to_vec(), Object::name("Transparency"));
+    group.set(b"CS".to_vec(), Object::name("DeviceRGB"));
+    let mut form = Dict::new();
+    form.set(b"Type".to_vec(), Object::name("XObject"));
+    form.set(b"Subtype".to_vec(), Object::name("Form"));
+    form.set(b"BBox".to_vec(), Object::Array([0, 0, 200, 100].map(Object::Int).to_vec()));
+    form.set(b"Group".to_vec(), Object::Dict(group));
+    let mut mask = Dict::new();
+    mask.set(b"Type".to_vec(), Object::name("Mask"));
+    mask.set(b"S".to_vec(), Object::name("Luminosity"));
+    mask.set(b"G".to_vec(), Object::Ref(d.add(Object::Stream(Stream::flate(form, b"1 g 30 30 80 40 re f")))));
+    let mut state = Dict::new();
+    state.set(b"Type".to_vec(), Object::name("ExtGState"));
+    state.set(b"SMask".to_vec(), Object::Dict(mask));
+    let mut states = Dict::new();
+    states.set(b"SM".to_vec(), Object::Dict(state));
+    states
+}
+
+/// The soft mask is selected before a translation, so it is placed by the CTM before it. The
+/// paragraph lifted over the scan selects it again after its own `cm`: there it must be placed
+/// as it was, not 100 pt to the right where it would hide the new text, so the edit renders
+/// exactly as the same edit on the page without the mask. Both rewrite paths.
+#[test]
+fn a_soft_mask_selected_before_a_cm_stays_put_when_the_edit_is_lifted() {
+    for edit in ["Jane", "Jane\nDoe"] {
+        let mut plain = Session::new();
+        let page = under_scan("q 1 0 0 1 100 0 cm BT /F1 20 Tf 3 Tr -58 44 Td (John) Tj ET Q");
+        let plain_id = plain.open("plain.pdf", None, page, None).unwrap();
+        edit_block(&mut plain, plain_id, 0, edit);
+        let mut s = Session::new();
+        let page = under_scan_with("q /SM gs 1 0 0 1 100 0 cm BT /F1 20 Tf 3 Tr -58 44 Td (John) Tj ET Q", soft_mask_state);
+        let id = s.open("masked.pdf", None, page, None).unwrap();
+        assert_eq!(texts(&s, id), ["John"]);
+        edit_block(&mut s, id, 0, edit);
+        assert_eq!(texts(&s, id), [edit.replace('\n', " ")], "{edit:?}");
+        assert_edit_shows(&s, id, &format!("{edit:?} masked"));
+        let ink = |s: &Session, id| word_pixels(s, id).iter().filter(|p| near(**p, INK)).count();
+        assert_eq!(ink(&s, id), ink(&plain, plain_id), "{edit:?}: the mask does not hide the new text");
+    }
+}

crates/filters/README.md

@@ -27,10 +27,11 @@ encode(filter, params, data) -> Result<Vec<u8>, FilterError>
 encode_flate(data) -> Vec<u8>   // zlib, level 6
 encode_g4(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit rows as CCITT Group 4; columns <= MAX_G4_COLUMNS
 pub struct CcittParams { k, columns, rows, end_of_line, encoded_byte_align, end_of_block, black_is_1 }  // Table 11; Default = its defaults
-decode_ccitt(data, &params, max_rows) -> Result<Vec<u8>, FilterError>   // CCITT fax as CCITTFaxDecode gives it; columns <= MAX_CCITT_COLUMNS
-decode_jbig2(data, globals, columns, rows, max) -> Result<Vec<u8>, FilterError>   // JBIG2 as JBIG2Decode gives it; a page of columns × rows, within max and MAX_JBIG2_PIXELS
-encode_jbig2_generic(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit rows as lossless JBIG2 for JBIG2Decode; columns <= MAX_JBIG2_COLUMNS
-encode_jbig2(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit rows as lossless JBIG2 for JBIG2Decode, symbol coded when that is smaller; columns <= MAX_JBIG2_COLUMNS
+decode_ccitt_within(data, &params, max_rows, work: &mut u64) -> Result<Vec<u8>, FilterError>   // CCITT fax as CCITTFaxDecode gives it; columns <= MAX_CCITT_COLUMNS; its rows paid for from work before they are decoded
+decode_jbig2_within(data, globals, columns, rows, max, work: &mut u64) -> Result<Vec<u8>, FilterError>   // JBIG2 as JBIG2Decode gives it; a page of columns × rows, within max and MAX_JBIG2_PIXELS; reading and decoding it spend from work, in the decoder's steps
+encode_jbig2_generic(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit rows as lossless JBIG2 for JBIG2Decode; columns and rows <= MAX_JBIG2_COLUMNS (65,535) and MAX_JBIG2_PIXELS (2^28) samples, what the decoder takes
+encode_jbig2(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit rows as lossless JBIG2 for JBIG2Decode, symbol coded when that is smaller; the same limits
+encode_jbig2_shared(&[(data, columns, rows)]) -> Result<Option<SharedJbig2>, FilterError>   // images symbol coded sharing one dictionary: the /JBIG2Globals data, and each image's stream or None; the same limits
 ```
 
 - `chain` is applied first to last, as in a `/Filter` array.
@@ -50,8 +51,8 @@ encode_jbig2(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit row
 | ASCIIHexDecode | white space ignored, odd digit padded with 0, `>` EOD (optional), other characters → Corrupt | upper case, newline every 64 digits, `>` |
 | ASCII85Decode | `<~` prefix, `z`, white space, `~>` (or bare `~`, or none) EOD, final partial group; `z` inside a group, a 1-char final group, overflow or bad characters → Corrupt | `z` for zero groups, newline every 75 characters, `~>` |
 | RunLengthDecode | 0–127 literal, 129–255 repeat, 128 EOD (optional); truncated run → Corrupt | runs of ≥2 repeat, literals up to 128, 128 |
-| CCITTFaxDecode | not in a chain (`Unsupported`); `decode_ccitt` decodes Group 3 and Group 4 on its own, as rows of 1-bit samples each on a new byte, black 0 unless `black_is_1`, at most `max_rows` rows (fewer with `/Rows`), the rows before any damage, up to 1,048,576 samples a row; Group 3 rows on bytes are read by their end-of-line codes when the data starts with one and on bytes otherwise, whatever `end_of_line` says, so data with codes but none before the first row (not as T.4 sends them) is read on bytes, as the renderer draws it, and at `k` 0 may come out as other rows (`pdfcraft_cos::Document::decoded_image` calls it for a fax image, after the filters before it) | `encode_g4`: Group 4 (`/K -1`) with an end-of-block mark, 0 bits coded black so `/BlackIs1 false` decodes the same bits; rows packed MSB first, each on a new byte, padding bits and trailing bytes ignored; up to 32,767 samples a row (the encoder counts positions in 16 bits); no rows or columns, or too wide → Unsupported, too few bytes → Corrupt |
-| JBIG2Decode | not in a chain (`Unsupported`); `decode_jbig2` decodes it on its own with `hayro-jbig2`, given what its `/JBIG2Globals` decode to, as rows of 1-bit samples each on a new byte, black 0; the page has to be `columns` × `rows` (PdfCraft's renderer draws the whole page into the image), within `max` bytes as such rows and 2^28 pixels (`MAX_JBIG2_PIXELS`, about the most the decoder takes), checked before it is decoded; regions inside it are bounded by the decoder alone (a region may claim more pixels than its page); damaged data, or globals that don't decode, are `Corrupt` (`pdfcraft_cos::Document::decoded_image` calls it for a JBIG2 image, after the filters before it) | `encode_jbig2_generic`: the embedded organisation (D.3) with a page information segment and an immediate lossless generic region (7.4.6), no `/JBIG2Globals`; template 0 with its nominal AT pixels and typical prediction (6.2.5), coded with the MQ arithmetic coder (Annex E, Table E.1) and ended by its 0xFF 0xAC marker. A 0 sample is coded as a JBIG2 1 (black), since `JBIG2Decode` gives black as 0, so the stream decodes to the same bits; rows packed MSB first, each on a new byte, padding bits and trailing bytes ignored; up to 1,048,576 samples a row; no rows or columns, or too wide → Unsupported, too few bytes → Corrupt. `encode_jbig2`: the smaller of that and symbol coding (`jbig2/symbols.rs`): each distinct mark (8-connected black pixels, at most 256 a side) stored once in a symbol dictionary (7.4.2; arithmetic coded, each bitmap a template 0 generic region without typical prediction, the bitmaps sharing their contexts) and placed by immediate lossless text regions referring to it (7.4.3; bottom-left reference corner, strips of 1, 2, 4 or 8 rows, whichever is smallest), each of at most 10,000 instances over a band of rows, as the decoder PdfCraft renders with (`hayro-jbig2`) takes no more in one region, with larger marks, and in a second plan marks that occur once, in a generic region over their box. Only exact copies share a symbol (no refinement), so the stream decodes to the same bits; fewer than two symbols, more than 2^20 black runs, 65,536 distinct marks or 16 MiB of their pixels, or more than 2^24 rows, and the generic coding is used; a plan of more than 32,767 symbols (that decoder refuses more) isn't made |
+| CCITTFaxDecode | not in a chain (`Unsupported`); `decode_ccitt_within` decodes Group 3 and Group 4 on its own, as rows of 1-bit samples each on a new byte, black 0 unless `black_is_1`, at most `max_rows` rows (fewer with `/Rows`), the rows before any damage, up to 1,048,576 samples a row; Group 3 rows on bytes are read by their end-of-line codes when the data starts with one and on bytes otherwise, whatever `end_of_line` says, so data with codes but none before the first row (not as T.4 sends them) is read on bytes, as the renderer draws it, and at `k` 0 may come out as other rows (`pdfcraft_cos::ImageBudget::decode` calls it for a fax image, after the filters before it) | `encode_g4`: Group 4 (`/K -1`) with an end-of-block mark, 0 bits coded black so `/BlackIs1 false` decodes the same bits; rows packed MSB first, each on a new byte, padding bits and trailing bytes ignored; up to 32,767 samples a row (the encoder counts positions in 16 bits); no rows or columns, or too wide → Unsupported, too few bytes → Corrupt |
+| JBIG2Decode | not in a chain (`Unsupported`); `decode_jbig2_within` decodes it on its own with `hayro-jbig2`, given what its `/JBIG2Globals` decode to, as rows of 1-bit samples each on a new byte, black 0; the page has to be `columns` × `rows` (PdfCraft's renderer draws the whole page into the image), within `max` bytes as such rows and 2^28 pixels (`MAX_JBIG2_PIXELS`, the most the decoder takes), checked before it is decoded; regions inside it are bounded by the decoder alone (a region may claim more pixels than its page); damaged data, or globals that don't decode, are `Corrupt` (`pdfcraft_cos::ImageBudget::decode` calls it for a JBIG2 image, after the filters before it) | `encode_jbig2_generic`: the embedded organisation (D.3) with a page information segment and an immediate lossless generic region (7.4.6), no `/JBIG2Globals`; template 0 with its nominal AT pixels and typical prediction (6.2.5), coded with the MQ arithmetic coder (Annex E, Table E.1) and ended by its 0xFF 0xAC marker. A 0 sample is coded as a JBIG2 1 (black), since `JBIG2Decode` gives black as 0, so the stream decodes to the same bits; rows packed MSB first, each on a new byte, padding bits and trailing bytes ignored; up to 65,535 samples on a side and 2^28 in all, where `hayro-jbig2` stops; no rows or columns, or too large → Unsupported, too few bytes → Corrupt. `encode_jbig2`: the smaller of that and symbol coding (`jbig2/symbols.rs`): each distinct mark (8-connected black pixels, at most 256 a side) stored once in a symbol dictionary (7.4.2; arithmetic coded, each bitmap a template 0 generic region without typical prediction, the bitmaps sharing their contexts) and placed by immediate lossless text regions referring to it (7.4.3; bottom-left reference corner, strips of 1, 2, 4 or 8 rows, whichever is smallest), each of at most 10,000 instances over a band of rows, as the decoder PdfCraft renders with (`hayro-jbig2`) takes no more in one region, with larger marks, and in a second plan marks that occur once, in a generic region over their box. Only exact copies share a symbol (no refinement), so the stream decodes to the same bits; fewer than two symbols, more than 2^20 black runs, 65,536 distinct marks or 16 MiB of their pixels, and the generic coding is used; a plan of more than 32,767 symbols (that decoder refuses more) isn't made. `encode_jbig2_shared`: the marks found in more than one image of a group (at most 16,383, those in the most images first, within the same limits on distinct marks and their pixels as one image's) go once in a symbol dictionary segment associated with no page, number 0, which is the `/JBIG2Globals` data (7.2.6, D.3); each image's stream numbers its segments from 1 (a segment refers only to lower numbers, 7.2.5) and its text regions refer to that dictionary first, then to one of its own for the marks only it repeats, so the shared symbols' IDs come first (Table 31's SBSYMS); the rest is coded as `encode_jbig2`'s symbol coding codes it, the smaller of its two plans. An image that places none of the shared marks gets no stream, to be stored alone; whether the rest save more than the globals take is the caller's to weigh |
 
 ## Tests
 
@@ -61,8 +62,8 @@ encode_jbig2(data, columns, rows) -> Result<Vec<u8>, FilterError>   // 1-bit row
 - `ccitt.rs`: `decode_ccitt` gives back the rows `encode_g4` was given (with `/BlackIs1`, `/Rows` and a row limit), refuses bad widths, and bounds its output for any input; byte-aligned Group 3 in each layout, over 32 seeded pictures, decodes to its picture, and a byte short to fewer rows. Group 4 output decoded by `hayro-ccitt` (an independent decoder) matches the input bits: a text-like page, padding bits, the widest row, and property tests over bitmaps of noise and of runs; any input returns rather than panics.
 - `mq.rs`: the arithmetic coder reproduces Annex H.2's 30 bytes from its 256 decisions.
 - `jbig2.rs`: output decoded by `hayro-jbig2` (dev-dependency, an independent decoder) matches the input bits: a text-like page (smaller than Group 4), edges, padding, all-white and all-black regions (typical rows), and property tests over bitmaps of noise and of runs; any input returns rather than panics.
-- `jbig2/decode.rs`: `decode_jbig2` gives back the rows of both codings, padding bits 0; refuses a page of another width or height, past `max` or past `MAX_JBIG2_PIXELS` before decoding it (2^28 pixels take about 34 MB, a bit each), globals that aren't JBIG2 and damaged data, and returns rather than panics on every prefix of a stream.
-- `jbig2/symbols.rs`: the integer coders against Annex A's example and Table A.1; symbol-coded output decoded by `hayro-jbig2` matches the input bits for every plan and strip size: text whose letters repeat (under half the generic coding's size, the dictionary retained and referred to), large and lone marks left to a generic region, marks on the edges, touching at corners and inside each other's boxes, and property tests over glyphs scattered over each other and the edges with stray pixels (never larger than the generic coding); one shape, a blank page and noise are coded generically; marks joined at a corner, either way, are one mark, and 256 pixels a side is a symbol while 257 wide or tall is left out; black padding bits are ignored; coordinates past 4,435 use Annex A's 32-bit range and PREV stays below 512; past 2^20 runs, 2^24 rows, 65,536 distinct marks or 2^24 symbol pixels the image is coded generically, and at each cap it is still looked at; a plan codes at most 32,767 symbols, which decode, and past that the second plan still codes the repeated ones; more than 10,000 marks are placed by several text regions, numbered in turn, the dictionary retained for each but the last; any input returns rather than panics.
+- `jbig2/decode.rs`: `decode_jbig2_within` gives back the rows of both codings, padding bits 0; refuses a page of another width or height, past `max` or past `MAX_JBIG2_PIXELS` before decoding it (2^28 pixels take about 34 MB, a bit each), globals that aren't JBIG2 and damaged data, and returns rather than panics on every prefix of a stream.
+- `jbig2/symbols.rs`: the integer coders against Annex A's example and Table A.1; symbol-coded output decoded by `hayro-jbig2` matches the input bits for every plan and strip size: text whose letters repeat (under half the generic coding's size, the dictionary retained and referred to), large and lone marks left to a generic region, marks on the edges, touching at corners and inside each other's boxes, and property tests over glyphs scattered over each other and the edges with stray pixels (never larger than the generic coding); one shape, a blank page and noise are coded generically; marks joined at a corner, either way, are one mark, and 256 pixels a side is a symbol while 257 wide or tall is left out; black padding bits are ignored; coordinates past 4,435 use Annex A's 32-bit range and PREV stays below 512; past 2^20 runs, 65,536 distinct marks or 2^24 symbol pixels the image is coded generically, and at each cap it is still looked at; a plan codes at most 32,767 symbols, which decode, and past that the second plan still codes the repeated ones; more than 10,000 marks are placed by several text regions, numbered in turn, the dictionary retained for each but the last; pages in one font share one dictionary, segment 0 of no page, retained, which each page's text regions refer to first, taking less together than alone, a page's own repeated marks in a dictionary referred to after it, a page sharing nothing left alone, images with fewer than two marks in common sharing nothing, and past 16,383 shared marks those in the most images kept, with a property test over groups of scattered pages; any input returns rather than panics.
 - `fuzz/`: a detached cargo-fuzz crate (`cargo +nightly fuzz run decode`, run from `crates/filters/`).
 
 ## Status

crates/filters/src/jbig2.rs

@@ -1,8 +1,9 @@
 //! JBIG2 encoding (ITU-T T.88 | ISO/IEC 14492), for `JBIG2Decode` (ISO 32000-2 §7.4.7), lossless:
 //! a generic region, template 0 with its nominal adaptive pixels, typical prediction on, MQ
-//! arithmetic coding ([`crate::mq`]); or the image's marks as symbols ([`symbols`]). Written from
-//! the standard's 6.2.5 (coding a generic region), 7.2 (segment headers), 7.4.1, 7.4.6 and 7.4.8
-//! (the segments) and D.3 (the embedded organisation PDF uses). Decoding is in [`decode`].
+//! arithmetic coding ([`crate::mq`]); or the image's marks as symbols ([`symbols`]), which a group
+//! of images may share through `/JBIG2Globals`. Written from the standard's 6.2.5 (coding a generic
+//! region), 7.2 (segment headers), 7.4.1, 7.4.6 and 7.4.8 (the segments) and D.3 (the embedded
+//! organisation PDF uses). Decoding is in [`decode`].
 
 mod decode;
 mod symbols;
@@ -12,9 +13,11 @@ pub use decode::{MAX_JBIG2_PIXELS, decode_jbig2_within};
 use crate::FilterError;
 use crate::mq::{Context, MqEncoder};
 
-/// The widest row [`encode_jbig2_generic`] encodes. JBIG2 allows 32-bit widths; this keeps a
-/// row's buffers small and its positions in range.
-pub const MAX_JBIG2_COLUMNS: u32 = 1 << 20;
+/// The widest row, and the most rows, [`encode_jbig2_generic`] encodes: what `hayro-jbig2`, the
+/// decoder behind `JBIG2Decode` here, takes on a side. JBIG2 allows 32-bit sizes, but past this
+/// nothing here could read the stream, and the optimizer, which doesn't read back what it stores,
+/// replaced such an image with one that draws nothing.
+pub const MAX_JBIG2_COLUMNS: u32 = 65_535;
 
 /// Template 0's pixels (Figure 3), as (x, y) offsets from the pixel being coded, each a bit of the
 /// context in this order: the four on the current row, the five fixed ones on the row above, the
@@ -54,9 +57,7 @@ const PAD: usize = 4;
 /// Errors: as [`encode_jbig2_generic`].
 pub fn encode_jbig2(data: &[u8], columns: u32, rows: u32) -> Result<Vec<u8>, FilterError> {
     let generic = encode_jbig2_generic(data, columns, rows)?;
-    // `encode_jbig2_generic` checked that the rows are there.
-    let stride = (columns as usize).div_ceil(8);
-    let samples = usize::try_from(rows).ok().and_then(|r| r.checked_mul(stride)).and_then(|n| data.get(..n));
+    let samples = rows_to_encode(data, columns, rows).ok();
     Ok(match samples.and_then(|s| symbols::encode(s, columns, rows)) {
         Some(coded) if coded.len() < generic.len() => coded,
         _ => generic,
@@ -72,18 +73,13 @@ pub fn encode_jbig2(data: &[u8], columns: u32, rows: u32) -> Result<Vec<u8>, Fil
 /// samples have it. Bytes after the last row are ignored, as are the bits that pad a row to a whole
 /// byte.
 ///
-/// Errors: no rows or columns, or rows wider than [`MAX_JBIG2_COLUMNS`]
-/// ([`FilterError::Unsupported`]); fewer bytes than the rows need ([`FilterError::Corrupt`]).
+/// Errors: no rows or columns, more of either than [`MAX_JBIG2_COLUMNS`], or more samples than
+/// [`MAX_JBIG2_PIXELS`], what the decoder takes ([`FilterError::Unsupported`]); fewer bytes than the
+/// rows need ([`FilterError::Corrupt`]).
 pub fn encode_jbig2_generic(data: &[u8], columns: u32, rows: u32) -> Result<Vec<u8>, FilterError> {
-    if columns == 0 || rows == 0 || columns > MAX_JBIG2_COLUMNS {
-        return Err(FilterError::Unsupported(format!("JBIG2 encoding of {columns} × {rows} samples")));
-    }
+    let samples = rows_to_encode(data, columns, rows)?;
     let width = columns as usize;
     let stride = width.div_ceil(8);
-    let samples = usize::try_from(rows).ok().and_then(|r| r.checked_mul(stride)).and_then(|n| data.get(..n)).ok_or_else(|| FilterError::Corrupt {
-        filter: "JBIG2Decode",
-        detail: format!("{} bytes for {rows} rows of {columns} samples", data.len()),
-    })?;
     let mut contexts: Vec<Context> = vec![0; 1 << 16];
     let mut mq = MqEncoder::new();
     let height = samples.len() / stride;
@@ -101,6 +97,48 @@ pub fn encode_jbig2_generic(data: &[u8], columns: u32, rows: u32) -> Result<Vec<
     Ok(out)
 }
 
+/// The samples of `rows` rows of `columns` 1-bit samples in `data`, when the encoders here take
+/// that size; the errors are [`encode_jbig2_generic`]'s.
+fn rows_to_encode(data: &[u8], columns: u32, rows: u32) -> Result<&[u8], FilterError> {
+    let too_large = columns > MAX_JBIG2_COLUMNS || rows > MAX_JBIG2_COLUMNS || u64::from(columns) * u64::from(rows) > MAX_JBIG2_PIXELS;
+    if columns == 0 || rows == 0 || too_large {
+        return Err(FilterError::Unsupported(format!("JBIG2 encoding of {columns} × {rows} samples")));
+    }
+    let stride = (columns as usize).div_ceil(8);
+    usize::try_from(rows)
+        .ok()
+        .and_then(|r| r.checked_mul(stride))
+        .and_then(|n| data.get(..n))
+        .ok_or_else(|| FilterError::Corrupt { filter: "JBIG2Decode", detail: format!("{} bytes for {rows} rows of {columns} samples", data.len()) })
+}
+
+/// A group of images coded by [`encode_jbig2_shared`]: the data of the `/JBIG2Globals` stream
+/// they share, and each image's own stream, in the order given, or `None` for one that shares
+/// nothing with the others.
+#[derive(Debug)]
+pub struct SharedJbig2 {
+    pub globals: Vec<u8>,
+    pub images: Vec<Option<Vec<u8>>>,
+}
+
+/// Images, each `rows` rows of `columns` 1-bit PDF samples, as lossless JBIG2 sharing one symbol
+/// dictionary: the marks found in more than one of them are stored once, in a symbol dictionary
+/// segment not associated with a page, which is the `/JBIG2Globals` stream's data, and each image's
+/// stream, in the embedded organisation, places them from there, with its other marks coded as
+/// [`encode_jbig2`]'s symbol coding codes them (see [`symbols`]). With the globals, each decodes to
+/// its own bits. An image that holds none of those marks, or that symbol coding doesn't take, has
+/// no stream here; it is stored alone. `None` when the images share fewer than two marks.
+///
+/// What each image's stream saves is left for the caller to weigh against what the globals take,
+/// which the images that use them share.
+///
+/// Errors: as [`encode_jbig2_generic`], for the first image it would refuse.
+pub fn encode_jbig2_shared(images: &[(&[u8], u32, u32)]) -> Result<Option<SharedJbig2>, FilterError> {
+    let images =
+        images.iter().map(|(data, columns, rows)| Ok((rows_to_encode(data, *columns, *rows)?, *columns, *rows))).collect::<Result<Vec<_>, _>>()?;
+    Ok(symbols::encode_shared(&images).map(|(globals, images)| SharedJbig2 { globals, images }))
+}
+
 /// A page information segment's data (7.4.8): the page's size, resolution unknown, eventually
 /// lossless, default pixel 0 (white), OR combination, not striped.
 fn page_information(columns: u32, rows: u32) -> Vec<u8> {
@@ -141,12 +179,18 @@ fn at_pixels(out: &mut Vec<u8>) {
     }
 }
 
-/// A segment (7.2): its header (number, type, the segments it refers to, page 1, data length),
-/// then its data. `retained`: a later segment refers to this one. `refers_to` holds each
+/// A segment (7.2) of page 1: its header (number, type, the segments it refers to, the page, data
+/// length), then its data. `retained`: a later segment refers to this one. `refers_to` holds each
 /// referred-to segment's number and whether a segment after this one refers to it too (its
 /// retain bit, 7.2.4). Segment numbers here stay below 256, so each referred-to one takes a byte
 /// (7.2.5); a segment refers to at most four, so their count and retain bits take one byte too.
 fn segment(out: &mut Vec<u8>, number: u32, kind: u8, refers_to: &[(u8, bool)], retained: bool, data: &[u8]) {
+    segment_of(out, 1, number, kind, refers_to, retained, data);
+}
+
+/// [`segment`], of page `page`: 0 for a segment associated with no page (7.2.6), such as the
+/// global ones `/JBIG2Globals` holds, which a page's segments may refer to.
+fn segment_of(out: &mut Vec<u8>, page: u8, number: u32, kind: u8, refers_to: &[(u8, bool)], retained: bool, data: &[u8]) {
     out.extend_from_slice(&number.to_be_bytes());
     out.push(kind);
     // At most four, so the count fits its three bits.
@@ -154,8 +198,8 @@ fn segment(out: &mut Vec<u8>, number: u32, kind: u8, refers_to: &[(u8, bool)], r
     let kept = refers_to.iter().enumerate().fold(0u8, |bits, (k, (_, kept))| bits | u8::from(*kept) << (k + 1));
     out.push((refers_to.len() as u8) << 5 | kept | u8::from(retained));
     out.extend(refers_to.iter().map(|(n, _)| *n));
-    out.push(1);
-    // A segment's data never comes near 4 GiB here: a row is at most 1 MiB wide.
+    out.push(page);
+    // A segment's data never comes near 4 GiB here: an image is at most 2^28 samples.
     out.extend_from_slice(&u32::try_from(data.len()).unwrap_or(u32::MAX).to_be_bytes());
     out.extend_from_slice(data);
 }
@@ -212,6 +256,11 @@ mod tests {
     /// The rows an independent decoder (`hayro-jbig2`) reads from `data`, as PDF samples: true
     /// for white (a JBIG2 0).
     pub(super) fn decode(data: &[u8]) -> Vec<Vec<bool>> {
+        decode_with(data, None)
+    }
+
+    /// [`decode`], with `/JBIG2Globals`.
+    pub(super) fn decode_with(data: &[u8], globals: Option<&[u8]>) -> Vec<Vec<bool>> {
         struct Rows(Vec<Vec<bool>>, Vec<bool>, usize);
         impl hayro_jbig2::Decoder for Rows {
             fn push_pixel(&mut self, black: bool) {
@@ -226,7 +275,7 @@ mod tests {
                 self.0.push(row);
             }
         }
-        let image = hayro_jbig2::Image::new_embedded(data, None).unwrap();
+        let image = hayro_jbig2::Image::new_embedded(data, globals).unwrap();
         let mut rows = Rows(Vec::new(), Vec::new(), image.width() as usize);
         image.decode(&mut rows).unwrap();
         rows.0
@@ -343,9 +392,56 @@ mod tests {
     fn what_it_cannot_encode_is_an_error() {
         assert!(matches!(encode_jbig2_generic(&[0; 8], 0, 1), Err(FilterError::Unsupported(_))));
         assert!(matches!(encode_jbig2_generic(&[0; 8], 8, 0), Err(FilterError::Unsupported(_))));
-        assert!(matches!(encode_jbig2_generic(&[0; 8], MAX_JBIG2_COLUMNS + 1, 1), Err(FilterError::Unsupported(_))));
         assert!(matches!(encode_jbig2_generic(&[0; 3], 16, 2), Err(FilterError::Corrupt { .. })), "two rows of 16 need 4 bytes");
-        assert!(matches!(encode_jbig2_generic(&[], 1, u32::MAX), Err(FilterError::Corrupt { .. })));
+        assert!(matches!(encode_jbig2_generic(&[], 1, 2), Err(FilterError::Corrupt { .. })));
+    }
+
+    /// The encoder stops where the decoder does, on each side and in total: past that it would
+    /// write a stream nothing here can read. 16,384 squared is exactly the bound on samples.
+    /// `encode_jbig2_shared` refuses what `encode_jbig2_generic` refuses: an image taller than
+    /// the decoder takes is `Unsupported`, one at the bound isn't refused. (Its one tall mark is
+    /// too large to be a symbol, so nothing is shared: `Ok(None)`.)
+    #[test]
+    fn shared_coding_takes_only_what_the_decoder_takes() {
+        let past = vec![0x7F; MAX_JBIG2_COLUMNS as usize + 1];
+        let tall = (&past[..], 1, MAX_JBIG2_COLUMNS + 1);
+        assert!(matches!(encode_jbig2_shared(&[tall, tall]), Err(FilterError::Unsupported(_))), "too tall");
+        let at = (&past[..MAX_JBIG2_COLUMNS as usize], 1, MAX_JBIG2_COLUMNS);
+        assert!(matches!(encode_jbig2_shared(&[at, at]), Ok(None)), "at the bound");
+    }
+
+    #[test]
+    fn it_encodes_only_what_the_decoder_takes() {
+        let unsupported = |columns, rows| matches!(encode_jbig2_generic(&[], columns, rows), Err(FilterError::Unsupported(_)));
+        assert!(unsupported(MAX_JBIG2_COLUMNS + 1, 1), "too wide");
+        assert!(unsupported(1, MAX_JBIG2_COLUMNS + 1), "too tall");
+        assert!(unsupported(16_385, 16_384), "too many samples, each side within the bound");
+        assert!(unsupported(u32::MAX, u32::MAX), "the product doesn't overflow");
+        // At the bounds what it writes reads back, through the decoder that has to read it.
+        let wide = vec![0x0F; (MAX_JBIG2_COLUMNS as usize).div_ceil(8) * 4];
+        assert_eq!(decode(&encode_jbig2_generic(&wide, MAX_JBIG2_COLUMNS, 4).unwrap()), unpack(&wide, MAX_JBIG2_COLUMNS, 4));
+        let tall = vec![0x7F; MAX_JBIG2_COLUMNS as usize];
+        assert_eq!(decode(&encode_jbig2_generic(&tall, 1, MAX_JBIG2_COLUMNS).unwrap()), unpack(&tall, 1, MAX_JBIG2_COLUMNS));
+        struct Rows(u32, u64);
+        impl hayro_jbig2::Decoder for Rows {
+            fn push_pixel(&mut self, black: bool) {
+                self.1 += u64::from(black);
+            }
+            fn push_pixel_chunk(&mut self, black: bool, chunks: u32) {
+                self.1 += u64::from(black) * u64::from(chunks) * 8;
+            }
+            fn next_line(&mut self) {
+                self.0 += 1;
+            }
+        }
+        // One black pixel, so a page that came back blank wouldn't pass.
+        let mut largest = vec![0xFF; 2_048 * 16_384];
+        largest[0] = 0x7F;
+        let largest = encode_jbig2_generic(&largest, 16_384, 16_384).unwrap();
+        let mut rows = Rows(0, 0);
+        hayro_jbig2::Image::new_embedded(&largest, None).unwrap().decode(&mut rows).unwrap();
+        assert_eq!(rows.0, 16_384);
+        assert_eq!(rows.1, 1);
     }
 
     proptest::proptest! {

crates/filters/src/jbig2/decode.rs

@@ -4,7 +4,8 @@ use crate::FilterError;
 use crate::ccitt::Rows;
 
 /// The largest JBIG2 page [`decode_jbig2_within`] decodes, in pixels. The decoder decodes a page whole,
-/// and takes pages of up to about this many (20,000 × 10,000 decodes).
+/// and takes pages of up to this many (20,000 × 10,000 decodes). It is also the most
+/// [`encode_jbig2_generic`](crate::encode_jbig2_generic) encodes, so what it stores reads back.
 pub const MAX_JBIG2_PIXELS: u64 = 1 << 28;
 
 /// A `JBIG2Decode` stream's `data`, with what its `/JBIG2Globals` stream decodes to, decoded as the
@@ -143,6 +144,143 @@ mod tests {
         assert_eq!(decode_jbig2(&symbols, None, w, h, usize::MAX).unwrap(), marks);
     }
 
+    /// A region's location is unsigned (ISO/IEC 14492 5.4.4), so one past `i32::MAX` is off the
+    /// page. The decoder took it for a signed one: a region at 0xFFFFFFFC came back onto the page
+    /// four pixels left of it, and a refinement anywhere past `i32::MAX` was refused, and the page
+    /// with it. Each stream is a page of 16 × 12 covered by a generic region, then a region of 8 × 6
+    /// of one kind past `i32::MAX`, coded by the standard's procedures, and decodes to that page
+    /// alone; moved onto the page, the region draws. Vendored hayro-jbig2 patch 14.
+    #[test]
+    fn a_region_located_past_i32_max_is_off_the_page() {
+        const PAGE: &str = "0000000030000100000013000000100000000c00000000000000004200000000000126000100000035000000100000000c0000000000000000040003fffdff02fefefed906aa2cb6ee4ccb4bc975d02669ca7a9c14c20c638f5a5e1bffac";
+        let cases = [
+            // At 0xFFFFFFFC, 1.
+            ("generic", "00000002260001000000220000000800000006fffffffc00000001000003fffdff02fefefe17c876ae6f77ffac"),
+            // At 1, 0xFFFFFFFE, with its symbol dictionary.
+            (
+                "text",
+                "000000020000010000001e000003fffdff02fefefe00000001000000014fdda14149cec477ed5fffac00000003062002010000001b000000080000000600000001fffffffe00001000000001a943ffac",
+            ),
+            // At 0xFFFFFFFC, 1, with its pattern dictionary.
+            (
+                "halftone",
+                "000000021000010000000a000101000000011fffac00000003162002010000002e0000000800000006fffffffc0000000100000000000800000006000000000000000001000000d09301774485ffac",
+            ),
+            // At 0xFFFFFFFC, 1, reading the page there (7.4.7.4): 0s.
+            ("refinement of the page", "000000022a00010000001e0000000800000006fffffffc000000010400ffffffff0bd98f188428ffac"),
+            // Of an intermediate region at the same place (7.4.7.5), 1, 0xFFFFFFFE.
+            (
+                "refinement of a region",
+                "0000000224000100000023000000080000000600000001fffffffe000003fffdff02fefefe3d81322da16b7fffac000000032a2002010000001e000000080000000600000001fffffffe0000ffffffffe29946b82229ffac",
+            ),
+            // Of an intermediate refinement of an intermediate region, all at 0xFFFFFFFC, 1.
+            (
+                "refinement of a refinement",
+                "00000002240001000000230000000800000006fffffffc00000001000003fffdff02fefefecdfd921ec8c47fffac00000003282002010000001e0000000800000006fffffffc000000010000ffffffff903cdb447a47ffac000000042a2003010000001e0000000800000006fffffffc000000010000ffffffffdcd6078cab86ffac",
+            ),
+        ];
+        let hex = |text: &str| (0..text.len() / 2).map(|i| u8::from_str_radix(&text[i * 2..i * 2 + 2], 16).unwrap()).collect::<Vec<u8>>();
+        let decode = |segments: &str| decode_jbig2(&[hex(PAGE), hex(segments)].concat(), None, 16, 12, usize::MAX).unwrap();
+        let page = decode("");
+        assert!(page.iter().any(|&byte| byte != 0xFF), "the page has ink");
+        for (kind, segments) in cases {
+            assert_eq!(decode(segments), page, "{kind}");
+            // Moved onto the page, to 4, 1 or 1, 2, the same regions draw: they decode, and are
+            // left out for where they are.
+            let (off, on) = [("fffffffc00000001", "0000000400000001"), ("00000001fffffffe", "0000000100000002")]
+                .into_iter()
+                .find(|(off, _)| segments.contains(off))
+                .unwrap();
+            assert_ne!(decode(&segments.replace(off, on)), page, "{kind} on the page");
+        }
+
+        // A refinement at 2, 0 of an intermediate region at 0x80000000, 0. A refinement of a
+        // region refines it where it is, "GRREFERENCEDX 0, GRREFERENCEDY 0" (Table 35), and the two
+        // should be at one place (7.4.7.5). Where they aren't, it decodes as it does where they are.
+        const ELSEWHERE: &str = "000000022400010000002300000008000000068000000000000000000003fffdff02fefefe1bca3149568cdfffac000000032a2002010000001e000000080000000600000002000000000000ffffffff784a909cc761ffac";
+        let refined = decode(ELSEWHERE);
+        assert_eq!(refined, decode(&ELSEWHERE.replace("8000000000000000", "0000000200000000")), "the region at 2, 0 too");
+        assert_ne!(refined, page, "drawn");
+    }
+
+    /// A refinement of the page refines "the current contents of the page buffer, restricted to the
+    /// area of the page buffer specified by this segment's region segment information field"
+    /// (ISO/IEC 14492 7.4.7.4), at an offset of 0 (Table 35), and reads 0 outside that area
+    /// (6.3.5.2). The decoder read the page around the area too, and refused a refinement wider or
+    /// taller than the page. A refinement of another region refines that region, not the page. And
+    /// a reference 32 or more left of a refinement (GRREFERENCEDX below −31, as a symbol refined
+    /// with an RDX below −31 has, Table 18) is read from where each row starts in it: each row's
+    /// first context read 0 for the reference column it starts at, and from 33 left for the one
+    /// before it too. Each stream is coded by the standard's procedures and decodes to its
+    /// picture, `#` for black. Vendored hayro-jbig2 patch 16.
+    #[test]
+    fn a_refinement_refines_the_page_in_its_area_and_any_reference_where_it_is() {
+        let cases: [(&str, &str, &[&str]); 5] = [
+            (
+                "a 48 × 6 page a generic region has inked, refined at 33: ink on both sides of the area, template 0",
+                "000000003000010000001300000030000000060000000000000000420000000000012600010000004100000030000000060000000000000000040003fffdff02fefefe331433558a5c5056cf412003ec9a38164df39bd4463b9331502c4fb1c267ab77b665aa5962ffac000000022a0001000000210000000c0000000600000021000000000400ffffffff9a6c35bbeee221f687ffac",
+                &[
+                    ".#..##.######..#.#..#####.##..#........##.##..##",
+                    ".#..####.####.#...###.##.##.#.#.....#.#.####.###",
+                    "##.#......#..#....#..#.###.#..#.#####.###.######",
+                    "......#....###.#.##..#.##........#.#.#...#####..",
+                    "#.##..###.#.#.##.....#...#.#..#.##.#..#...#...#.",
+                    ".###...#..#..#..##..#.#..#####.#.##.......###.##",
+                ],
+            ),
+            (
+                "a 24 × 8 inked page refined at 5, 1, template 1",
+                "000000003000010000001300000018000000080000000000000000420000000000012600010000003500000018000000080000000000000000040003fffdff02fefefeb1e133cb8bcbb8510e81d219bb880dfb40a311dc5c298819efffac000000022a00010000001b0000000a0000000500000005000000010401e55c0078dcd30fffac",
+                &[
+                    "#.##.##...##....##.##..#",
+                    "#.##.##...#.####..##..#.",
+                    "##..##.##...#...###..#.#",
+                    ".....#.#.##.#...###....#",
+                    "..#.#...#.#...#.#...##.#",
+                    "....######...#.####....#",
+                    "..######..##.#.#..##.#..",
+                    "...#..##.####.#..##...#.",
+                ],
+            ),
+            (
+                "a 16 × 5 inked page refined by a region 4 wider than it, template 0",
+                "000000003000010000001300000010000000050000000000000000420000000000012600010000002600000010000000050000000000000000040003fffdff02fefefe22e5e253a429cbf2c701ffac000000022a000100000023000000140000000500000000000000000400ffffffff3afa516532bbe3d481926fffac",
+                &[".#.#.#.#..#.#.#.", "##.####..###...#", "..####.#..####.#", ".###.#.....#..#.", "#.###..#########"],
+            ),
+            (
+                "an intermediate region at 4, 1 on an inked 20 × 8 page, refined there (OR): the region, not the page, template 0",
+                "000000003000010000001300000014000000080000000000000000420000000000012600010000003000000014000000080000000000000000040003fffdff02fefefeb91e434e1726ca89ed06c2bffb0fe5fa7fccc80fffac00000002240001000000230000000a000000050000000400000001000003fffdff02fefefece7a9826ba81bfffac000000032a2002010000001e0000000a0000000500000004000000010000ffffffffd046ee6f6190ffac",
+                &[
+                    "#.#.#....#.#...#....",
+                    "##..#.#.#.##.....##.",
+                    "##.#.#.#.#.###.##...",
+                    "###.##.####..###.#.#",
+                    "...#.###..###.#.#..#",
+                    "#...#######.#...####",
+                    "..##.##...#..##..#.#",
+                    "#...##...#.##....#..",
+                ],
+            ),
+            (
+                "a symbol refined in a symbol dictionary from a 40 × 6 one, RDX −33: 33 left, template 1",
+                "0000000030000100000013000000070000000600000000000000004200000000000100000100000036000003fffdff02fefefe00000001000000014f913296209e2187f37bddb8589c8beb7d70109de7124ebe47d04914ef7e655c3c4cffac00000002002001010000001f100203fffdff02fefefe00000001000000014fe451a27bddf49f7ef7e7ffac00000003062002010000001b0000000700000006000000000000000004001000000001a943ffac",
+                &[".####.#", ".##..##", "......#", "...#..#", "#.#.###", "....##."],
+            ),
+        ];
+        let hex = |text: &str| (0..text.len() / 2).map(|i| u8::from_str_radix(&text[i * 2..i * 2 + 2], 16).unwrap()).collect::<Vec<u8>>();
+        for (form, stream, picture) in cases {
+            let (w, h) = (picture[0].len(), picture.len());
+            // As the filter gives it: black as 0, each row padded to a byte with 0s.
+            let mut rows = vec![0u8; w.div_ceil(8) * h];
+            for (y, row) in picture.iter().enumerate() {
+                for (x, _) in row.bytes().enumerate().filter(|(_, c)| *c == b'.') {
+                    rows[y * w.div_ceil(8) + x / 8] |= 0x80 >> (x % 8);
+                }
+            }
+            assert_eq!(decode_jbig2(&hex(stream), None, w as u32, h as u32, usize::MAX).unwrap(), rows, "{form}");
+        }
+    }
+
     /// What a page costs is the same however much a run has left. Given exactly that it decodes,
     /// and less stops it: spending all that's left, and what comes after isn't read. A page that
     /// fails still spends what it took.
@@ -182,6 +320,57 @@ mod tests {
         assert_eq!(u64::MAX - work, 4 * 14);
     }
 
+    /// A refinement whose reference is offset right of it (GRREFERENCEDX above 0, as a refined text
+    /// instance has from a wider bitmap, ISO/IEC 14492 Table 12, and a refined symbol from an RDX
+    /// above 0, Table 18) reads the reference from its first column. Left of the reference the
+    /// decoder emptied what it had read of it, and at its first column didn't read it again, so its
+    /// first 32 columns read as 0: such a refinement decoded to other pixels than were coded, or
+    /// failed. Each stream is a refinement coded by the standard's procedures on a page of its own
+    /// size, and decodes to its picture, `#` for black. Vendored hayro-jbig2 patch 15.
+    #[test]
+    fn a_refinement_reads_a_reference_right_of_it_from_its_first_column() {
+        let cases: [(&str, &str, &[&str]); 4] = [
+            (
+                "a text instance of an 8 × 6 symbol refined 6 wider: 3 right, template 0",
+                "00000000300001000000130000000e000000060000000000000000420000000000010000010000001d000003fffdff02fefefe00000001000000014fdd3dba48bdddde35ffac00000002062001010000002c0000000e000000060000000000000000040012ffffffff00000001a96b4a6b78b7fc094fadde1b3e881fffac",
+                &[".#.#.#....#...", "##.###....##.#", ".###...###..#.", "#.......#...#.", "#.####.#...#..", "#.##...###.#.."],
+            ),
+            (
+                "refined 2 wider and 2 taller, RDX and RDY 1: 2 right, 2 down, template 1",
+                "00000000300001000000130000000a000000080000000000000000420000000000010000010000001d000003fffdff02fefefe00000001000000014fdd9c52d3ea827a43ffac0000000206200101000000280000000a00000008000000000000000004801200000001a96c00cdac6dd5f6f848ce872411cfffac",
+                &["####.##...", "####..####", "####..##..", "...##...#.", "#......#..", "..#.....#.", "##....####", ".#........"],
+            ),
+            (
+                "a symbol refined in a symbol dictionary, RDX 5, RDY −1, template 0 with its AT pixels moved",
+                "00000000300001000000130000000c000000060000000000000000420000000000010000010000001e000003fffdff02fefefe00000001000000014fdda13efc4029efc95fffac000000020020010100000027000203fffdff02fefefefeff010100000001000000014fc98c352dd84a906f120ffb49793fffac00000003062002010000001b0000000c00000006000000000000000004001000000001a943ffac",
+                &["#.#.##.#.###", "..#.#.....##", "##..#...#...", "..##....##..", "##.#.##.####", ".#..#####..#"],
+            ),
+            (
+                "a text instance of a 40 × 5 symbol refined 2 wider, RDX 1: 2 right, across a word, template 0",
+                "00000000300001000000130000002a0000000500000000000000004200000000000100000100000031000003fffdff02fefefe00000001000000015240f590d953ae3f4069dede672090d4d61b377906d3f41aafa4f77107ffac00000002062001010000003c0000002a000000050000000000000000040012ffffffff00000001a96c0b9386d4b140486bdc3673dbd031490e468c7f7813d19068ab04a79cbfffac",
+                &[
+                    "##.#.#..##.##.#####.#....#.#.#..#..######.",
+                    ".#.#..###....#..##.#..#.####.#..#.###...##",
+                    ".#.#......#....#####....#...###...#####...",
+                    "#...##.##.......#...###.###...##..##.###.#",
+                    "..#..###..###..#...#.......##.#........##.",
+                ],
+            ),
+        ];
+        let hex = |text: &str| (0..text.len() / 2).map(|i| u8::from_str_radix(&text[i * 2..i * 2 + 2], 16).unwrap()).collect::<Vec<u8>>();
+        for (form, stream, picture) in cases {
+            let (w, h) = (picture[0].len(), picture.len());
+            // As the filter gives it: black as 0, each row padded to a byte with 0s.
+            let mut rows = vec![0u8; w.div_ceil(8) * h];
+            for (y, row) in picture.iter().enumerate() {
+                for (x, _) in row.bytes().enumerate().filter(|(_, c)| *c == b'.') {
+                    rows[y * w.div_ceil(8) + x / 8] |= 0x80 >> (x % 8);
+                }
+            }
+            assert_eq!(decode_jbig2(&hex(stream), None, w as u32, h as u32, usize::MAX).unwrap(), rows, "{form}");
+        }
+    }
+
     /// The page has to be the image's size, and is bounded before it is decoded, being decoded
     /// whole: within `max` as rows of one bit, and within [`MAX_JBIG2_PIXELS`]. Globals are given
     /// to the decoder: ones it skips decode, ones that aren't JBIG2 are an error, as is damaged
@@ -213,4 +402,87 @@ mod tests {
             let _ = decode_jbig2(&data[..end], None, w, h, usize::MAX);
         }
     }
+
+    /// Pixels past a bitmap's edge are 0 (ISO/IEC 14492 6.3.5.2). A page whose default pixel is 1,
+    /// and an intermediate text or halftone region whose default pixel is 1, kept 1s past their
+    /// width in their last word of each row, and a refinement, which reads its reference a word at
+    /// a time, read them as pixels: of rows not a multiple of 32 wide, it decoded to other pixels
+    /// than were coded. Each stream is a refinement coded by the standard's procedures from a
+    /// reference read as 0 past its edge, and decodes to the picture given, `#` for black.
+    /// Vendored hayro-jbig2 patch 13.
+    #[test]
+    fn a_refinement_reads_nothing_past_its_references_width() {
+        // A page of 7 × 6, then of 33 × 6, whose default pixel is 1, refined whole.
+        const PAGE_7: &str = "000000003000010000001300000007000000060000000000000000460000000000012a00010000001e000000070000000600000000000000000400ffffffffe42d7e889ebcffac";
+        const PAGE_33: &str = "000000003000010000001300000021000000060000000000000000460000000000012a000100000034000000210000000600000000000000000400ffffffff314a8d598037eb3f915ab3d526ccae915ad6a6a7b814111b124ae60fffac";
+        // An intermediate text region of 31 × 6 whose default pixel is 1, then one of 7 × 6 on a
+        // page of 40, each refined into the page.
+        const TEXT_31: &str = "00000000300001000000130000001f0000000600000000000000004200000000000100000100000030000003fffdff02fefefe00000001000000014f96dceb76c7f1ff585971969cd9f88e538261a6f713be68d77e8e1fffac00000002042001010000001b0000001f00000006000000000000000000029000000001a943ffac000000032a2002010000002f0000001f0000000600000000000000000400ffffffff9ac311688adbc8f570a2f96aef93d332e3b1f4b27b704bffac";
+        const TEXT_7: &str = "000000003000010000001300000028000000060000000000000000420000000000010000010000001d000003fffdff02fefefe00000001000000014fe1f79f4a95c5b77fffac00000002042001010000001b0000000700000006000000000000000000029000000001a943ffac000000032a2002010000001e000000070000000600000000000000000400ffffffffa71dae12bd7fffac";
+        // An intermediate halftone region of 33 × 6 whose default pixel is 1, refined into the page.
+        const HALFTONE_33: &str = "000000003000010000001300000021000000060000000000000000420000000000011000010000000a000101000000011fffac00000002142001010000004100000021000000060000000000000000009000000021000000060000000000000000010000004ea6618f551d48ff24c2c5c98124d449f2adea6fca76e4297fffac000000032a20020100000032000000210000000600000000000000000400ffffffffe87db809393a3251e565e7a749e6470ab37f7aef186ceaf5167bffac";
+        let cases: [(&str, &str, [&str; 6]); 5] = [
+            ("page 7", PAGE_7, ["###.#.#", ".......", "#.####.", "######.", "#.#...#", ".#...##"]),
+            (
+                "page 33",
+                PAGE_33,
+                [
+                    ".#..##........###..####....#.##.#",
+                    ".#.###.###.##.##..#..#...#.....##",
+                    ".....##..#....#.##.######.###..#.",
+                    "##...#..##.###..###.##..#.#.#.#.#",
+                    ".##.#........##.#.#.....###......",
+                    "...#.#####.#..#.###......###..###",
+                ],
+            ),
+            (
+                "text 31",
+                TEXT_31,
+                [
+                    "....##....###......#.##.#.#....",
+                    ".#.....##.......##..###.#...#..",
+                    ".#.#.#.####...#####.####...#.#.",
+                    "......#...#...#.##...##...#..#.",
+                    ".#..##.###.#.###..####...#...#.",
+                    "#...#...#..#.#....#.##.#.....#.",
+                ],
+            ),
+            (
+                "text 7 on a page of 40",
+                TEXT_7,
+                [
+                    "......#.................................",
+                    ".....##.................................",
+                    "##...##.................................",
+                    "..#.....................................",
+                    "##......................................",
+                    "..#.....................................",
+                ],
+            ),
+            (
+                "halftone 33",
+                HALFTONE_33,
+                [
+                    "##...#.###.#.###.....#.####..####",
+                    "##.##.#...#.##.##.##.#...#.#.###.",
+                    "###..#.#....##.###...#..##.##..##",
+                    "##..#...###...##..#.####.###.#...",
+                    "####.###.###.#..#..#.#.####...###",
+                    "#.#..#........#....#.#.##.##..#.#",
+                ],
+            ),
+        ];
+        let hex = |text: &str| (0..text.len() / 2).map(|i| u8::from_str_radix(&text[i * 2..i * 2 + 2], 16).unwrap()).collect::<Vec<u8>>();
+        for (form, stream, picture) in cases {
+            let w = picture[0].len();
+            // As the filter gives it: black as 0, each row padded to a byte with 0s.
+            let mut rows = vec![0u8; w.div_ceil(8) * picture.len()];
+            for (y, row) in picture.iter().enumerate() {
+                for (x, _) in row.bytes().enumerate().filter(|(_, c)| *c == b'.') {
+                    rows[y * w.div_ceil(8) + x / 8] |= 0x80 >> (x % 8);
+                }
+            }
+            assert_eq!(decode_jbig2(&hex(stream), None, w as u32, 6, usize::MAX).unwrap(), rows, "{form}");
+        }
+    }
 }

crates/filters/src/jbig2/symbols.rs

@@ -11,7 +11,7 @@ use std::collections::HashMap;
 use std::hash::{DefaultHasher, Hash, Hasher};
 use std::ops::Range;
 
-use super::{at_pixels, code_generic, generic_region, page_information, region_information, segment};
+use super::{at_pixels, code_generic, generic_region, page_information, region_information, segment, segment_of};
 use crate::mq::{Context, MqEncoder};
 
 /// The longest side of a mark stored as a symbol. A larger one is left to the generic region.
@@ -27,7 +27,9 @@ const MAX_SYMBOLS: usize = 1 << 16;
 const MAX_SYMBOL_PIXELS: usize = 1 << 24;
 
 /// The most symbols one plan codes. The decoder PdfCraft renders JBIG2 with (`hayro-jbig2`)
-/// refuses 32,768 symbols or more, and others may too, so a plan with more isn't made.
+/// refuses a dictionary whose new and exported symbols pass 65,535 together, and a plan exports
+/// every symbol it codes, so it refuses 32,768 or more; others may too, so a plan with more isn't
+/// made.
 const MAX_CODED_SYMBOLS: usize = (1 << 15) - 1;
 
 /// The most symbol instances one text region places. The decoder PdfCraft renders JBIG2 with
@@ -35,14 +37,14 @@ const MAX_CODED_SYMBOLS: usize = (1 << 15) - 1;
 /// placed by several regions, each over a band of rows, all referring to the one dictionary.
 const MAX_REGION_INSTANCES: usize = 10_000;
 
-// Segment numbers stay at most 256, so a referred-to one takes a byte (7.2.5): the page, the
-// dictionary, a text region for each MAX_REGION_INSTANCES of at most MAX_RUNS marks, and the
-// generic region.
-const _: () = assert!(MAX_RUNS.div_ceil(MAX_REGION_INSTANCES) + 3 <= 256);
+/// The most symbols a group's shared dictionary holds ([`encode_shared`]): half of what a page may
+/// place, so each page keeps room for its own.
+const MAX_SHARED_SYMBOLS: usize = MAX_CODED_SYMBOLS / 2;
 
-/// The most rows symbol coded. With rows at most 2^20 samples wide, every coordinate and
-/// difference coded then fits the 32-bit integers Annex A codes.
-const MAX_ROWS: u32 = 1 << 24;
+// Segment numbers stay at most 256, so a referred-to one takes a byte (7.2.5): the shared
+// dictionary, the page, its own dictionary, a text region for each MAX_REGION_INSTANCES of at most
+// MAX_RUNS marks, and the generic region.
+const _: () = assert!(MAX_RUNS.div_ceil(MAX_REGION_INSTANCES) + 4 <= 256);
 
 /// The integer coders' ranges (Table A.1): how many 1 bits pick the range, how many bits give the
 /// offset into it, and its first value. The last range has no 0 after its prefix.
@@ -99,20 +101,111 @@ struct Instance {
     height: u32,
 }
 
+/// A group of images coded by [`encode_shared`]: the globals' data, and each image's stream.
+type SharedCoding = (Vec<u8>, Vec<Option<Vec<u8>>>);
+
+/// The symbols of a group's shared dictionary, as one image's [`plan`] places them: the ID each of
+/// the image's symbols has there, if it is there, and how many symbols that dictionary exports.
+struct Shared {
+    ids: Vec<Option<u32>>,
+    count: u32,
+}
+
 /// `rows` rows of `columns` 1-bit PDF samples (black 0), symbol coded: the smaller of two plans,
 /// every mark of at most [`MAX_SYMBOL_SIDE`] a side as a symbol, or only those with a copy.
 /// `None` when neither plan has from two to [`MAX_CODED_SYMBOLS`] symbols, or the image is too
 /// large or too busy to look at.
 pub(super) fn encode(samples: &[u8], columns: u32, rows: u32) -> Option<Vec<u8>> {
-    let page = page(samples, columns, rows)?;
-    [1, 2].into_iter().filter_map(|copies| plan(&page, columns, rows, copies, None)).min_by_key(Vec::len)
+    let page = page(samples, columns)?;
+    [1, 2].into_iter().filter_map(|copies| plan(&page, columns, rows, copies, None, None)).min_by_key(Vec::len)
+}
+
+/// Images, each as [`encode`] takes one, symbol coded sharing one dictionary: the globals' data, a
+/// symbol dictionary segment associated with no page (number 0) holding the distinct marks found
+/// in more than one image, and each image's stream placing them from there, the smaller of
+/// [`encode`]'s two plans for its other marks. The group's marks are held within the limits one
+/// image's are ([`MAX_SYMBOLS`], [`MAX_SYMBOL_PIXELS`]): past them, later marks aren't shared. Past
+/// [`MAX_SHARED_SYMBOLS`] shared marks, those in the most images are kept.
+///
+/// An image too large or too busy to look at, or that places none of the shared marks, gets `None`;
+/// `None` overall when fewer than two marks are shared.
+pub(super) fn encode_shared(images: &[(&[u8], u32, u32)]) -> Option<SharedCoding> {
+    // The group's distinct marks, each with how many images hold it (as its uses), looked at an
+    // image at a time.
+    let mut table: Vec<Symbol> = Vec::new();
+    let mut by_hash: HashMap<u64, Vec<u32>> = HashMap::new();
+    let mut held = 0usize;
+    for (samples, columns, _) in images {
+        let Some(page) = page(samples, *columns) else { continue };
+        // An image's symbols are distinct, so each counts an image once.
+        for symbol in page.symbols {
+            match find(&table, &by_hash, &symbol) {
+                Some(t) => {
+                    if let Some(s) = table.get_mut(t as usize) {
+                        s.uses = s.uses.saturating_add(1);
+                    }
+                }
+                None => {
+                    let Some(more) = held.checked_add(symbol.pixels.len()).filter(|h| *h <= MAX_SYMBOL_PIXELS && table.len() < MAX_SYMBOLS) else {
+                        continue;
+                    };
+                    held = more;
+                    let t = u32::try_from(table.len()).ok()?;
+                    by_hash.entry(fingerprint(&symbol)).or_default().push(t);
+                    table.push(Symbol { uses: 1, ..symbol });
+                }
+            }
+        }
+    }
+    let uses = |t: &u32| table.get(*t as usize).map_or(0, |s| s.uses);
+    let mut shared: Vec<u32> = (0..u32::try_from(table.len()).ok()?).filter(|t| uses(t) >= 2).collect();
+    if shared.len() < 2 {
+        return None;
+    }
+    shared.sort_by_key(|t| std::cmp::Reverse(uses(t)));
+    shared.truncate(MAX_SHARED_SYMBOLS);
+    // The dictionary's order, as `plan` keeps it.
+    shared.sort_by_key(|t| table.get(*t as usize).map(|s| (s.height, s.width)));
+    let mut global = vec![None; table.len()];
+    for (k, t) in shared.iter().enumerate() {
+        if let Some(slot) = global.get_mut(*t as usize) {
+            *slot = u32::try_from(k).ok();
+        }
+    }
+    let symbols: Vec<&Symbol> = shared.iter().filter_map(|t| table.get(*t as usize)).collect();
+    let mut globals = Vec::new();
+    segment_of(&mut globals, 0, 0, 0, &[], true, &symbol_dictionary(&symbols)?);
+    let count = u32::try_from(symbols.len()).ok()?;
+    let streams = images
+        .iter()
+        .map(|(samples, columns, rows)| {
+            let page = page(samples, *columns)?;
+            let ids = page.symbols.iter().map(|s| find(&table, &by_hash, s).and_then(|t| global.get(t as usize).copied().flatten())).collect();
+            let shared = Shared { ids, count };
+            [1, 2].into_iter().filter_map(|copies| plan(&page, *columns, *rows, copies, None, Some(&shared))).min_by_key(Vec::len)
+        })
+        .collect();
+    Some((globals, streams))
+}
+
+/// What sorts a symbol's bitmap ([`symbols`] and [`encode_shared`] look exact copies up by it).
+fn fingerprint(s: &Symbol) -> u64 {
+    let mut hasher = DefaultHasher::new();
+    (s.width, s.height, &s.pixels).hash(&mut hasher);
+    hasher.finish()
+}
+
+/// The index in `table` of the symbol with `s`'s bitmap, looked up by its [`fingerprint`].
+fn find(table: &[Symbol], by_hash: &HashMap<u64, Vec<u32>>, s: &Symbol) -> Option<u32> {
+    by_hash
+        .get(&fingerprint(s))?
+        .iter()
+        .copied()
+        .find(|t| table.get(*t as usize).is_some_and(|t| (t.width, t.height) == (s.width, s.height) && t.pixels == s.pixels))
 }
 
 /// The image's marks and symbols; `None` past the limits above.
-fn page(samples: &[u8], columns: u32, rows: u32) -> Option<Page> {
-    if rows > MAX_ROWS {
-        return None;
-    }
+fn page(samples: &[u8], columns: u32) -> Option<Page> {
     let width = usize::try_from(columns).ok()?;
     let stride = width.div_ceil(8);
     if stride == 0 {
@@ -272,23 +365,18 @@ fn symbols(page: &mut Page) -> Option<()> {
             page.large.push(m);
             continue;
         }
-        let pixels = pixels(mark, &page.runs, &page.order);
-        let mut hasher = DefaultHasher::new();
-        (width, height, &pixels).hash(&mut hasher);
-        let same = by_hash.entry(hasher.finish()).or_default();
+        let symbol = Symbol { width, height, pixels: pixels(mark, &page.runs, &page.order), uses: 0 };
         let symbols = &mut page.symbols;
-        let known =
-            same.iter().copied().find(|s| symbols.get(*s as usize).is_some_and(|s| (s.width, s.height) == (width, height) && s.pixels == pixels));
-        let id = match known {
+        let id = match find(symbols, &by_hash, &symbol) {
             Some(id) => id,
             None => {
-                kept = kept.checked_add(pixels.len())?;
+                kept = kept.checked_add(symbol.pixels.len())?;
                 if kept > MAX_SYMBOL_PIXELS || symbols.len() == MAX_SYMBOLS {
                     return None;
                 }
                 let id = u32::try_from(symbols.len()).ok()?;
-                symbols.push(Symbol { width, height, pixels, uses: 0 });
-                same.push(id);
+                by_hash.entry(fingerprint(&symbol)).or_default().push(id);
+                symbols.push(symbol);
                 id
             }
         };
@@ -305,18 +393,28 @@ fn symbols(page: &mut Page) -> Option<()> {
 /// the other marks in a generic region. `None` with fewer than two such symbols (their IDs would
 /// take no bits at all, SBSYMCODELEN 0, a corner of the standard left alone here) or more than
 /// [`MAX_CODED_SYMBOLS`].
-fn plan(page: &Page, columns: u32, rows: u32, copies: u32, log_strips: Option<u32>) -> Option<Vec<u8>> {
+///
+/// With `shared`, the symbols a group's dictionary holds are placed from there, whatever their uses
+/// here, and the page's own dictionary holds only the others (none, when it has none), as
+/// [`encode_shared`] writes them; `None` too for a page that places none of the shared ones.
+fn plan(page: &Page, columns: u32, rows: u32, copies: u32, log_strips: Option<u32>, shared: Option<&Shared>) -> Option<Vec<u8>> {
     let symbol = |s: u32| page.symbols.get(s as usize);
+    let global = |s: u32| shared.and_then(|g| g.ids.get(s as usize).copied().flatten());
+    let globals = shared.map_or(0, |g| g.count);
     // The dictionary's order (6.5.5): height classes from the shortest, each narrowest first.
-    let mut kept: Vec<u32> = (0..page.symbols.len() as u32).filter(|s| symbol(*s).is_some_and(|s| s.uses >= copies)).collect();
-    if kept.len() < 2 || kept.len() > MAX_CODED_SYMBOLS {
+    let mut kept: Vec<u32> =
+        (0..page.symbols.len() as u32).filter(|s| global(*s).is_none() && symbol(*s).is_some_and(|s| s.uses >= copies)).collect();
+    let count = usize::try_from(globals).ok()?.checked_add(kept.len())?;
+    if !(2..=MAX_CODED_SYMBOLS).contains(&count) {
         return None;
     }
     kept.sort_by_key(|s| symbol(*s).map(|s| (s.height, s.width)));
-    let mut id = vec![None; page.symbols.len()];
+    // The shared symbols' IDs come first, as their dictionary is referred to first (Table 31's
+    // SBSYMS).
+    let mut id: Vec<Option<u32>> = (0..page.symbols.len() as u32).map(global).collect();
     for (k, s) in kept.iter().enumerate() {
         if let Some(slot) = id.get_mut(*s as usize) {
-            *slot = u32::try_from(k).ok();
+            *slot = u32::try_from(k).ok().and_then(|k| k.checked_add(globals));
         }
     }
     let mut instances = Vec::new();
@@ -329,9 +427,12 @@ fn plan(page: &Page, columns: u32, rows: u32, copies: u32, log_strips: Option<u3
             _ => left.push(*m),
         }
     }
+    if shared.is_some() && !instances.iter().any(|i| i.id < globals) {
+        return None;
+    }
     let kept: Vec<&Symbol> = kept.iter().filter_map(|s| symbol(*s)).collect();
-    let dictionary = symbol_dictionary(&kept)?;
-    let count = u32::try_from(kept.len()).ok()?;
+    let dictionary = if kept.is_empty() { None } else { Some(symbol_dictionary(&kept)?) };
+    let count = u32::try_from(count).ok()?;
     // Bands of at most MAX_REGION_INSTANCES, from the top.
     instances.sort_by_key(|i| (i.t, i.s));
     let mut regions = Vec::new();
@@ -344,12 +445,21 @@ fn plan(page: &Page, columns: u32, rows: u32, copies: u32, log_strips: Option<u3
         });
     }
     let mut out = Vec::new();
-    segment(&mut out, 0, 48, &[], false, &page_information(columns, rows));
-    segment(&mut out, 1, 0, &[], true, &dictionary);
-    let mut number = 2;
+    // The shared dictionary is segment 0, in the globals, and a segment refers only to lower
+    // numbers (7.2.5): the page's own follow it.
+    let mut number = u32::from(shared.is_some());
+    segment(&mut out, number, 48, &[], false, &page_information(columns, rows));
+    number += 1;
+    let mut dictionaries: Vec<u8> = shared.map(|_| 0).into_iter().collect();
+    if let Some(dictionary) = &dictionary {
+        segment(&mut out, number, 0, &[], true, dictionary);
+        dictionaries.push(u8::try_from(number).ok()?);
+        number += 1;
+    }
     for (k, text) in regions.iter().enumerate() {
-        // The dictionary stays retained for the next region, until the last (7.2.4).
-        segment(&mut out, number, 7, &[(1, k + 1 < regions.len())], false, text);
+        // The dictionaries stay retained for the next region, until the last (7.2.4).
+        let refers_to: Vec<(u8, bool)> = dictionaries.iter().map(|n| (*n, k + 1 < regions.len())).collect();
+        segment(&mut out, number, 7, &refers_to, false, text);
         number += 1;
     }
     if !left.is_empty() {
@@ -543,8 +653,9 @@ fn encode_id(mq: &mut MqEncoder, contexts: &mut [Context], length: u32, id: u32)
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::jbig2::tests::{decode, samples, unpack};
-    use crate::jbig2::{encode_jbig2, encode_jbig2_generic};
+    use crate::FilterError;
+    use crate::jbig2::tests::{decode, decode_with, samples, unpack};
+    use crate::jbig2::{encode_jbig2, encode_jbig2_generic, encode_jbig2_shared};
 
     type Bitmap = Vec<Vec<u8>>;
 
@@ -665,11 +776,11 @@ mod tests {
     fn every_plan_round_trips(picture: &Bitmap) -> usize {
         let (columns, rows) = (picture[0].len() as u32, picture.len() as u32);
         let data = samples(picture);
-        let page = page(&data, columns, rows).unwrap();
+        let page = page(&data, columns).unwrap();
         let mut plans = 0;
         for copies in [1, 2] {
             for log_strips in 0..4 {
-                if let Some(coded) = plan(&page, columns, rows, copies, Some(log_strips)) {
+                if let Some(coded) = plan(&page, columns, rows, copies, Some(log_strips), None) {
                     assert_eq!(decode(&coded), unpack(&data, columns, rows), "{copies} copies, strips of {}", 1 << log_strips);
                     plans += 1;
                 }
@@ -735,10 +846,10 @@ mod tests {
                 row[stride - 1] &= 0xFF << (8 * stride - columns);
             }
             let (c, r) = (columns as u32, 120);
-            let page = page(&data, c, r).unwrap();
+            let page = page(&data, c).unwrap();
             assert!(page.marks.iter().all(|m| m.x1 as usize <= columns), "{columns} columns");
             for copies in [1, 2] {
-                if let Some(coded) = plan(&page, c, r, copies, None) {
+                if let Some(coded) = plan(&page, c, r, copies, None, None) {
                     assert_eq!(decode(&coded), unpack(&data, c, r), "{columns} columns");
                 }
             }
@@ -771,7 +882,7 @@ mod tests {
             row[290] = 1;
         }
         let data = samples(&picture);
-        let page = page(&data, 300, 300).unwrap();
+        let page = page(&data, 300).unwrap();
         let boxes: Vec<(u32, u32, u32, u32)> = page.marks.iter().map(|m| (m.x0, m.y0, m.x1 - m.x0, m.y1 - m.y0)).collect();
         assert_eq!(
             boxes,
@@ -792,18 +903,14 @@ mod tests {
         assert_eq!(every_plan_round_trips(&picture), 8);
     }
 
-    /// Past 2^20 black runs or 2^24 rows the image is left to generic coding; at either cap it is
-    /// still looked at.
+    /// Past 2^20 black runs the image is left to generic coding; at the cap it is still looked at.
     #[test]
-    fn busy_or_tall_images_are_left_to_generic_coding() {
+    fn busy_images_are_left_to_generic_coding() {
         // 0x55: four black pixels a byte, each its own run, under the same ones on the next row.
         let columns = 1 << 20;
         let row = vec![0x55u8; columns / 8];
-        assert!(page(&row.repeat(2), columns as u32, 2).is_some(), "2^20 runs");
-        assert!(page(&row.repeat(3), columns as u32, 3).is_none(), "1.5 × 2^20 runs");
-        let tall = vec![0xFFu8; MAX_ROWS as usize + 1];
-        assert!(page(&tall, 1, MAX_ROWS + 1).is_none());
-        assert!(page(&tall, 1, MAX_ROWS).is_some());
+        assert!(page(&row.repeat(2), columns as u32).is_some(), "2^20 runs");
+        assert!(page(&row.repeat(3), columns as u32).is_none(), "1.5 × 2^20 runs");
     }
 
     /// A plan codes at most 32,767 symbols, which an independent decoder reads back; with more,
@@ -828,18 +935,18 @@ mod tests {
             (samples(&picture), columns as u32, rows as u32)
         };
         let (data, columns, rows) = codes(MAX_CODED_SYMBOLS, 0);
-        let at_cap = page(&data, columns, rows).unwrap();
-        assert_eq!(decode(&plan(&at_cap, columns, rows, 1, None).unwrap()), unpack(&data, columns, rows));
+        let at_cap = page(&data, columns).unwrap();
+        assert_eq!(decode(&plan(&at_cap, columns, rows, 1, None, None).unwrap()), unpack(&data, columns, rows));
         // One more distinct mark, each once: neither plan is made.
         let (data, columns, rows) = codes(MAX_CODED_SYMBOLS + 1, 0);
-        let past = page(&data, columns, rows).unwrap();
-        assert!(plan(&past, columns, rows, 1, None).is_none() && plan(&past, columns, rows, 2, None).is_none());
+        let past = page(&data, columns).unwrap();
+        assert!(plan(&past, columns, rows, 1, None, None).is_none() && plan(&past, columns, rows, 2, None, None).is_none());
         assert_eq!(encode_jbig2(&data, columns, rows).unwrap(), encode_jbig2_generic(&data, columns, rows).unwrap());
         // With two of them repeated, the second plan codes those two.
         let (data, columns, rows) = codes(MAX_CODED_SYMBOLS + 1, 200);
-        let past = page(&data, columns, rows).unwrap();
-        assert!(plan(&past, columns, rows, 1, None).is_none());
-        assert_eq!(decode(&plan(&past, columns, rows, 2, None).unwrap()), unpack(&data, columns, rows));
+        let past = page(&data, columns).unwrap();
+        assert!(plan(&past, columns, rows, 1, None, None).is_none());
+        assert_eq!(decode(&plan(&past, columns, rows, 2, None, None).unwrap()), unpack(&data, columns, rows));
         // Above a page of text whose letters repeat, that second plan is the one `encode_jbig2`
         // keeps: the first, of every mark, would code too many symbols.
         let mut picture: Bitmap = vec![vec![0u8; 256 * 18]; 512];
@@ -857,10 +964,10 @@ mod tests {
         let coded = encode_jbig2(&data, columns, rows).unwrap();
         assert_eq!(segment_types(&coded)[1], 0, "symbol coded");
         assert_eq!(decode(&coded), unpack(&data, columns, rows));
-        let (data, columns, rows) = codes(MAX_SYMBOLS, 0);
-        assert_eq!(page(&data, columns, rows).map(|p| p.symbols.len()), Some(MAX_SYMBOLS));
-        let (data, columns, rows) = codes(MAX_SYMBOLS + 1, 0);
-        assert!(page(&data, columns, rows).is_none());
+        let (data, columns, _) = codes(MAX_SYMBOLS, 0);
+        assert_eq!(page(&data, columns).map(|p| p.symbols.len()), Some(MAX_SYMBOLS));
+        let (data, columns, _) = codes(MAX_SYMBOLS + 1, 0);
+        assert!(page(&data, columns).is_none());
         // `n` black squares of 256 × 256, each with a white pixel in a different place: 2^16
         // pixels a symbol, so 256 of them are exactly the cap.
         let squares = |n: usize| {
@@ -876,11 +983,11 @@ mod tests {
             (samples(&picture), columns as u32, rows as u32)
         };
         let (data, columns, rows) = squares(256);
-        let at_cap = page(&data, columns, rows).unwrap();
+        let at_cap = page(&data, columns).unwrap();
         assert_eq!(at_cap.symbols.len(), 256);
-        assert_eq!(decode(&plan(&at_cap, columns, rows, 1, None).unwrap()), unpack(&data, columns, rows));
-        let (data, columns, rows) = squares(257);
-        assert!(page(&data, columns, rows).is_none());
+        assert_eq!(decode(&plan(&at_cap, columns, rows, 1, None, None).unwrap()), unpack(&data, columns, rows));
+        let (data, columns, _) = squares(257);
+        assert!(page(&data, columns).is_none());
     }
 
     /// More than 10,000 marks are placed by several text regions, each of at most 10,000 (more
@@ -993,7 +1100,199 @@ mod tests {
         }
     }
 
+    /// Each segment's page association (7.2.6): the byte after the numbers it refers to.
+    fn associations(data: &[u8]) -> Vec<u8> {
+        let (mut pages, mut at) = (Vec::new(), 0);
+        while at < data.len() {
+            let refers = usize::from(data[at + 5] >> 5);
+            pages.push(data[at + 6 + refers]);
+            let length_at = at + 6 + refers + 1;
+            at = length_at + 4 + u32::from_be_bytes(data[length_at..length_at + 4].try_into().unwrap()) as usize;
+        }
+        pages
+    }
+
+    /// `pictures`, `columns` × `rows` each, coded sharing a dictionary; each image's stream, which
+    /// has to be there, decodes with the globals to its picture.
+    fn shared_round_trip(pictures: &[Bitmap]) -> (Vec<u8>, Vec<Vec<u8>>) {
+        let (columns, rows) = (pictures[0][0].len() as u32, pictures[0].len() as u32);
+        let data: Vec<Vec<u8>> = pictures.iter().map(|p| samples(p)).collect();
+        let images: Vec<(&[u8], u32, u32)> = data.iter().map(|d| (&d[..], columns, rows)).collect();
+        let shared = encode_jbig2_shared(&images).unwrap().unwrap();
+        let (globals, coded) = (shared.globals, shared.images);
+        let coded: Vec<Vec<u8>> = coded.into_iter().map(Option::unwrap).collect();
+        for (d, c) in data.iter().zip(&coded) {
+            assert_eq!(decode_with(c, Some(&globals)), unpack(d, columns, rows));
+        }
+        (globals, coded)
+    }
+
+    /// `font` with a stem 20 pixels tall down each glyph's left side: a font sharing no glyph with
+    /// any [`glyphs`] gives, whose glyphs are at most 18 pixels tall.
+    fn stemmed(font: &[Bitmap]) -> Vec<Bitmap> {
+        font.iter()
+            .map(|g| {
+                (0..g.len().max(20)).map(|y| std::iter::once(1).chain(g.get(y).cloned().unwrap_or_else(|| vec![0; g[0].len()])).collect()).collect()
+            })
+            .collect()
+    }
+
+    /// Mark `k` of a set of distinct ones: a stroke 33 pixels long with a pixel above every other
+    /// column for each 1 bit of `k`, below 2^17.
+    fn comb(k: usize) -> Bitmap {
+        let mut g = vec![vec![0u8; 33]; 2];
+        g[1].fill(1);
+        for bit in 0..17 {
+            g[0][2 * bit] = u8::from(k >> bit & 1 == 1);
+        }
+        g
+    }
+
+    /// The combs `ks`, 120 a row, the rows four pixels apart.
+    fn combs(ks: impl ExactSizeIterator<Item = usize>) -> Bitmap {
+        let mut page = vec![vec![0u8; 120 * 36]; ks.len().div_ceil(120) * 4];
+        for (i, k) in ks.enumerate() {
+            draw(&mut page, &comb(k), (i % 120 * 36) as i64, (i / 120 * 4) as i64);
+        }
+        page
+    }
+
+    /// The symbols a symbol dictionary segment exports (SDNUMEXSYMS, 7.4.2.1.4), in a stream
+    /// that is that segment alone: after its header, flags and adaptive pixels.
+    fn exported(globals: &[u8]) -> usize {
+        u32::from_be_bytes(globals[21..25].try_into().unwrap()) as usize
+    }
+
+    /// Pages in one font share its letters: one symbol dictionary, segment 0, associated with no
+    /// page and retained (7.2.4, 7.2.6), which each page's text region refers to first, its own
+    /// segments numbered after it (7.2.5). Together they take less than they take alone.
+    #[test]
+    fn pages_in_one_font_share_one_dictionary() {
+        let font = glyphs(40, 7);
+        let pictures: Vec<Bitmap> = (0..4).map(|seed| text(1200, 300, &font, 20 + seed)).collect();
+        let (globals, coded) = shared_round_trip(&pictures);
+        assert_eq!(segments(&globals), [(0, 0, true, vec![])]);
+        assert_eq!(associations(&globals), [0]);
+        let (mut shared, mut alone) = (globals.len(), 0);
+        for (picture, c) in pictures.iter().zip(&coded) {
+            let segments = segments(c);
+            assert_eq!(segments.first().map(|s| s.0), Some(1), "the page's own segments follow");
+            assert!(segments.iter().filter(|s| s.1 == 7).all(|s| s.3.first() == Some(&(0, false))), "{segments:?}");
+            assert!(associations(c).iter().all(|page| *page == 1));
+            shared += c.len();
+            alone += encode_jbig2(&samples(picture), 1200, 300).unwrap().len();
+        }
+        assert!(shared < alone, "shared {shared} bytes, alone {alone}");
+    }
+
+    /// Two pages alike place every mark from the shared dictionary and have none of their own; a
+    /// page with letters of its own as well keeps them in its own dictionary, referred to after the
+    /// shared one (its symbols' IDs follow), and the page with nothing shared has no stream.
+    #[test]
+    fn what_a_page_has_alone_stays_its_own() {
+        let (font, other) = (glyphs(30, 7), stemmed(&glyphs(20, 99)));
+        let same = text(900, 240, &font, 3);
+        let mut more = text(900, 240, &font, 4);
+        more.extend(text(900, 120, &other, 5));
+        let (globals, coded) = shared_round_trip(&[same.clone(), same.clone()]);
+        assert!(!globals.is_empty());
+        assert!(coded.iter().all(|c| segment_types(c) == [48, 7]), "{:?}", coded.iter().map(|c| segment_types(c)).collect::<Vec<_>>());
+        let with_more = |p: &Bitmap| p.iter().cloned().chain(std::iter::repeat_n(vec![0u8; 900], 120)).collect::<Bitmap>();
+        let (_, coded) = shared_round_trip(&[with_more(&same), more]);
+        assert_eq!(segment_types(&coded[1])[..3], [48, 0, 7]);
+        assert_eq!(segments(&coded[1])[2].3, [(0, false), (2, false)]);
+        let alone = text(900, 360, &other, 6);
+        let data: Vec<Vec<u8>> = [&same, &same, &alone].iter().map(|p| samples(p)).collect();
+        let images: Vec<(&[u8], u32, u32)> = vec![(&data[0], 900, 240), (&data[1], 900, 240), (&data[2], 900, 360)];
+        let (_, coded) = encode_shared(&images).unwrap();
+        assert!(coded[0].is_some() && coded[1].is_some() && coded[2].is_none());
+    }
+
+    /// Images that share fewer than two marks share nothing; two are enough.
+    #[test]
+    fn images_with_nothing_in_common_share_nothing() {
+        let font = glyphs(30, 7);
+        let (a, b) = (samples(&text(600, 200, &font, 1)), samples(&text(600, 200, &stemmed(&font), 1)));
+        assert!(encode_shared(&[(&a, 600, 200), (&b, 600, 200)]).is_none());
+        assert!(encode_shared(&[(&a, 600, 200)]).is_none(), "one image");
+        assert!(encode_shared(&[]).is_none());
+        // The two commonest letters of the first page, below the last line of the second.
+        let mut two = text(600, 200, &stemmed(&font), 1);
+        draw(&mut two, &font[0], 10, 180);
+        draw(&mut two, &font[1], 100, 180);
+        let two = samples(&two);
+        let (globals, coded) = encode_shared(&[(&a, 600, 200), (&two, 600, 200)]).unwrap();
+        assert_eq!(exported(&globals), 2);
+        assert_eq!(decode_with(coded[1].as_ref().unwrap(), Some(&globals)), unpack(&two, 600, 200));
+    }
+
+    /// The images of a group are checked as `encode_jbig2_generic` checks one, and an image it
+    /// would refuse refuses the group.
+    #[test]
+    fn a_group_with_an_image_the_encoder_refuses_is_refused() {
+        let page = samples(&text(600, 200, &glyphs(30, 7), 1));
+        assert!(matches!(encode_jbig2_shared(&[(&page, 600, 200), (&page[..10], 600, 200)]), Err(FilterError::Corrupt { .. })));
+        assert!(matches!(encode_jbig2_shared(&[(&page, 600, 200), (&page, 0, 200)]), Err(FilterError::Unsupported(_))));
+        assert!(encode_jbig2_shared(&[(&page, 600, 200), (&page, 600, 200)]).unwrap().is_some());
+    }
+
+    /// A group holds its distinct marks within what one image's are held to: past 65,536 a mark
+    /// first seen later isn't held, so isn't shared, while those held count every image they're
+    /// in. Ten marks of the first image are in two images after it, with 464 first seen there.
+    #[test]
+    fn past_the_marks_a_group_holds_later_ones_arent_shared() {
+        let (a, b) = (samples(&combs(0..40_000)), samples(&combs(40_000..65_536)));
+        let late = combs((0..10).chain(65_536..66_000).collect::<Vec<_>>().into_iter());
+        let (rows, late) = (late.len() as u32, samples(&late));
+        let (columns, a_rows, b_rows) = (120 * 36, 40_000u32.div_ceil(120) * 4, 25_536u32.div_ceil(120) * 4);
+        let images = [(&a[..], columns, a_rows), (&b[..], columns, b_rows), (&late[..], columns, rows), (&late[..], columns, rows)];
+        let (globals, coded) = encode_shared(&images).unwrap();
+        assert_eq!(exported(&globals), 10);
+        for c in &coded[2..] {
+            assert_eq!(decode_with(c.as_ref().unwrap(), Some(&globals)), unpack(&late, columns, rows));
+        }
+    }
+
+    /// Past what one dictionary shares, it keeps the marks the most images hold: 20,000 shared,
+    /// the first 10,000 in all three images and the rest in two. The third image then places all
+    /// its marks from it, and the other two code the rest themselves (in a dictionary of their own
+    /// or a generic region, whichever is smaller).
+    #[test]
+    fn past_the_shared_limit_the_most_widely_held_marks_are_shared() {
+        let (both, first) = (combs(0..20_000), combs(0..10_000));
+        let rows = both.len();
+        let first: Bitmap = first.iter().cloned().chain(std::iter::repeat_n(vec![0u8; 120 * 36], rows - first.len())).collect();
+        let (globals, coded) = shared_round_trip(&[both.clone(), both, first]);
+        assert_eq!(exported(&globals), MAX_SHARED_SYMBOLS);
+        assert_eq!(segment_types(&coded[2]), [48, 7]);
+        assert!(segment_types(&coded[0]).iter().any(|t| *t == 0 || *t == 39), "{:?}", segment_types(&coded[0]));
+    }
+
     proptest::proptest! {
+        /// Glyphs scattered over pages of one font: whatever is shared, every page with a stream
+        /// decodes with the globals to its picture.
+        #[test]
+        fn shared_groups_round_trip(
+            columns in 1usize..200,
+            rows in 1usize..100,
+            shapes in 2usize..8,
+            n in 0usize..60,
+            pages in 2usize..5,
+            seed in proptest::num::u64::ANY,
+        ) {
+            let font = glyphs(shapes, seed);
+            let data: Vec<Vec<u8>> = (0..pages).map(|p| samples(&scatter(columns, rows, &font, seed ^ p as u64, n))).collect();
+            let (c, r) = (columns as u32, rows as u32);
+            let images: Vec<(&[u8], u32, u32)> = data.iter().map(|d| (&d[..], c, r)).collect();
+            if let Some((globals, coded)) = encode_shared(&images) {
+                for (d, coded) in data.iter().zip(coded) {
+                    if let Some(coded) = coded {
+                        proptest::prop_assert_eq!(decode_with(&coded, Some(&globals)), unpack(d, c, r));
+                    }
+                }
+            }
+        }
+
         /// Glyphs anywhere, over the edges and each other, with stray pixels: every plan decodes to
         /// the picture, and `encode_jbig2` is never larger than the generic coding.
         #[test]
@@ -1024,6 +1323,7 @@ mod tests {
         fn any_input_returns(data in proptest::collection::vec(0u8..=255, 0..600), columns in 0u32..5000, rows in 0u32..80) {
             let _ = encode_jbig2(&data, columns, rows);
             let _ = encode(&data, columns, rows);
+            let _ = encode_shared(&[(&data, columns, rows), (&data, columns, rows.saturating_sub(1))]);
         }
     }
 }

crates/filters/src/lib.rs

@@ -27,7 +27,8 @@
 //! ```
 //!
 //! 1-bit samples can be encoded as CCITT Group 4 ([`encode_g4`]) or lossless JBIG2
-//! ([`encode_jbig2`]).
+//! ([`encode_jbig2`]), a group of images sharing their marks through `/JBIG2Globals`
+//! ([`encode_jbig2_shared`]).
 //!
 //! Every decoder is bounded by a caller-supplied `max_output` (decompression-bomb
 //! defence) and never panics on malformed input.
@@ -47,7 +48,7 @@ mod runlength;
 use std::borrow::Cow;
 
 pub use ccitt::{CcittParams, MAX_CCITT_COLUMNS, MAX_G4_COLUMNS, decode_ccitt_within, encode_g4};
-pub use jbig2::{MAX_JBIG2_COLUMNS, MAX_JBIG2_PIXELS, decode_jbig2_within, encode_jbig2, encode_jbig2_generic};
+pub use jbig2::{MAX_JBIG2_COLUMNS, MAX_JBIG2_PIXELS, SharedJbig2, decode_jbig2_within, encode_jbig2, encode_jbig2_generic, encode_jbig2_shared};
 
 /// A PDF stream filter, identified by its `/Filter` name.
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]

crates/forms/README.md

@@ -50,7 +50,10 @@ let cells: Vec<table::Cell> = grid.cells_for(names)?;      // "Table1_1", "Table
   keeps it: `/V` is stored as typed, the appearance draws `?` for those characters, the widget is
   marked with the first one (`pdfcraft_fonts::UNDRAWN_MARK`, cleared once all of it can be drawn)
   and the form sets `/NeedAppearances`, so other viewers draw the field from its value with fonts
-  that have them. Not in a document that declares PDF/A, which forbids that flag (`declares_pdfa`).
+  that have them. Not in a document that declares PDF/A, which forbids that flag (`declares_pdfa`:
+  the bytes `pdfaid:part` in XMP metadata each filter stage of which decodes within 8 MiB, the cap
+  preflight's Standards panel reads it with; preflight reads the identifier by its namespace, so a
+  packet that gives that namespace another prefix declares PDF/A there and not here).
   `undrawn_fields` lists the marked fields; the engine reports each edit that draws one, and
   flattening refuses to make that `?` permanent.
 - Displaying a form that leaves its appearances to the viewer (`/NeedAppearances`, or a text or

crates/forms/src/appearances.rs

@@ -212,13 +212,24 @@ impl FieldAppearanceCache {
     }
 }
 
-/// Whether the document's XMP metadata declares PDF/A conformance (`pdfaid:part`).
+/// The most each filter stage of the XMP metadata stream may decode for its PDF/A declaration to
+/// be read, the cap preflight's Standards panel reads it with: past it, metadata declares nothing
+/// there either.
+pub(crate) const MAX_XMP_BYTES: usize = 8 << 20;
+
+/// Whether the document's XMP metadata declares PDF/A conformance (the bytes `pdfaid:part`).
+/// Metadata a filter stage of which decodes past [`MAX_XMP_BYTES`] doesn't.
 pub fn declares_pdfa(doc: &Document) -> bool {
     let Some(root) = doc.root() else { return false };
     let Some(m) = doc.get(root).as_dict().and_then(|c| c.get(b"Metadata").cloned()) else { return false };
     let m = doc.resolve(&m);
     match &*m {
-        Object::Stream(s) => s.decoded().is_ok_and(|b| b.windows(11).any(|w| w == b"pdfaid:part")),
+        // Not a `DecodeBudget`, which counts every stage against one allowance: preflight bounds
+        // each stage, and the two must agree on metadata stored through a chain of filters.
+        // `/DecodeParms` is read only when direct, as preflight and organize read metadata too:
+        // PDF/A asks for it unfiltered, so only a file that breaks that reaches parameters here,
+        // and the readers go to `with_direct_parms` together or they disagree.
+        Object::Stream(s) => s.decoded_within(MAX_XMP_BYTES).is_ok_and(|b| b.windows(11).any(|w| w == b"pdfaid:part")),
         _ => false,
     }
 }

crates/forms/src/author/edit.rs

@@ -234,6 +234,7 @@ pub fn set_props(doc: &mut Document, name: &str, props: &FieldProps) -> Result<S
     let mut list_picked = None;
     let (sort_items, old_selection) = items_to_sort(doc, &f, props);
     let parent_default = ancestor_sets(doc, f.obj, b"DV");
+    let parent_limit = ancestor_sets(doc, f.obj, b"MaxLen");
     doc.update_dict(f.obj, |d| {
         d.set(b"Ff".to_vec(), Object::Int(ff as i64));
         if let Some(t) = &props.tooltip {
@@ -246,6 +247,8 @@ pub fn set_props(doc: &mut Document, name: &str, props: &FieldProps) -> Result<S
         if let Some(m) = props.max_len {
             match m {
                 Some(m) => d.set(b"MaxLen".to_vec(), Object::Int(m as i64)),
+                // An absent key would inherit the parent's limit; zero is "no limit" (`read.rs`).
+                None if parent_limit => d.set(b"MaxLen".to_vec(), Object::Int(0)),
                 None => {
                     d.remove(b"MaxLen");
                 }
@@ -583,10 +586,15 @@ fn apply_late_widget_props(
 }
 
 /// Name field `old` `new` in each field's Calculate script that reads it
-/// ([`crate::af::rename_in_calculation`]).
+/// ([`crate::af::rename_in_calculation`]). Script streams share one budget, as a reading of the
+/// form's scripts does, however many fields name the same stream; past it, a script is left as
+/// it is, like one that won't decode. A Calculate action several fields share by reference is
+/// read and rewritten once, in place, so they all read the new name.
 fn rename_in_calculations(doc: &mut Document, all: &[Field], old: &str, new: &str) -> Result<(), FormError> {
     let aa_of =
         |doc: &Document, r: ObjRef| doc.get(r).as_dict().and_then(|d| d.get(b"AA").map(|a| doc.resolve(a))).and_then(|a| a.as_dict().cloned());
+    let mut scripts = crate::script_budget();
+    let mut shared = std::collections::HashSet::new();
     for f in all {
         // The script is the field's, or its only widget's when the field has none, as
         // `actions_of` reads it.
@@ -595,12 +603,16 @@ fn rename_in_calculations(doc: &mut Document, all: &[Field], old: &str, new: &st
             _ => None,
         };
         let Some((owner, mut aa)) = aa_of(doc, f.obj).map(|aa| (f.obj, aa)).or_else(only_widget) else { continue };
+        let by_ref = aa.get(b"C").and_then(Object::as_ref);
+        if by_ref.is_some_and(|r| !shared.insert(r)) {
+            continue;
+        }
         let Some(mut action) = aa.get(b"C").and_then(|a| doc.resolve(a).as_dict().cloned()) else { continue };
         let js = match action.get(b"JS").map(|js| doc.resolve(js)).as_deref() {
             Some(Object::String(s)) => s.to_text(),
             // A stream that isn't UTF-8 reads with replacement characters, which must not be
             // written back in place of what it holds.
-            Some(Object::Stream(s)) => match s.decoded().ok().and_then(|b| String::from_utf8(b).ok()) {
+            Some(Object::Stream(s)) => match scripts.decode(s).ok().and_then(|b| String::from_utf8(b).ok()) {
                 Some(js) => js,
                 None => continue,
             },
@@ -608,6 +620,10 @@ fn rename_in_calculations(doc: &mut Document, all: &[Field], old: &str, new: &st
         };
         let Some(js) = crate::af::rename_in_calculation(&js, old, new) else { continue };
         action.set(b"JS".to_vec(), PdfString::text(&js));
+        if let Some(r) = by_ref {
+            doc.update_dict(r, |d| *d = action)?;
+            continue;
+        }
         aa.set(b"C".to_vec(), Object::Dict(action));
         doc.update_dict(owner, |d| d.set(b"AA".to_vec(), Object::Dict(aa)))?;
     }

crates/forms/src/detect.rs

@@ -6,7 +6,7 @@
 //! the shapes from a page's content, [`raster::shapes`] from a picture of the page (a scan).
 
 use pdfcraft_content::{Matrix, Pieces};
-use pdfcraft_cos::{Document, Object};
+use pdfcraft_cos::{DecodeBudget, Document, Object};
 
 pub mod raster;
 
@@ -49,6 +49,60 @@ pub struct Candidate {
 /// points along its sides (#2942: a cell drawn with a midpoint on each vertical side).
 const MAX_RECT_POINTS: usize = 16;
 
+/// Graphics states saved (`q`) and kept at once while detecting; deeper saves are counted, not kept.
+const MAX_SAVES: usize = 256;
+
+/// The graphics states a page saves (`q`) as detection follows its matrix: at most [`MAX_SAVES`]
+/// kept, deeper ones counted so each `Q` still closes its own. Of those not kept: the matrix when
+/// the first was made, which closing the last restores; the shallowest a `cm` changed the matrix
+/// in; and whether a `Q` has closed that one, so the matrix isn't known until the last closes.
+struct Saves {
+    kept: Vec<Matrix>,
+    lost: usize,
+    lost_base: Matrix,
+    moved_at: usize,
+    unknown: bool,
+}
+
+impl Default for Saves {
+    fn default() -> Self {
+        Saves { kept: Vec::new(), lost: 0, lost_base: Matrix::IDENTITY, moved_at: usize::MAX, unknown: false }
+    }
+}
+
+impl Saves {
+    fn save(&mut self, ctm: Matrix) {
+        if self.kept.len() < MAX_SAVES && self.lost == 0 {
+            self.kept.push(ctm);
+        } else {
+            if self.lost == 0 {
+                self.lost_base = ctm;
+            }
+            self.lost = self.lost.saturating_add(1);
+        }
+    }
+
+    fn restore(&mut self, ctm: &mut Matrix) {
+        if self.lost == 0 {
+            *ctm = self.kept.pop().unwrap_or(*ctm);
+            return;
+        }
+        self.lost -= 1;
+        if self.lost == 0 {
+            (*ctm, self.moved_at, self.unknown) = (self.lost_base, usize::MAX, false);
+        } else if self.lost < self.moved_at {
+            self.unknown = true;
+        }
+    }
+
+    /// A `cm` changed the matrix at the current depth.
+    fn moved(&mut self) {
+        if self.lost > 0 {
+            self.moved_at = self.moved_at.min(self.lost);
+        }
+    }
+}
+
 /// The rectangles and horizontal segments a page draws (stroked or filled), in user space.
 #[derive(Default)]
 struct DetectionPath {
@@ -125,7 +179,15 @@ impl DetectionPath {
     }
 }
 
+/// The shapes page `page`'s content draws, its streams decoded within one page's allowance
+/// ([`DecodeBudget::page`]), however often `/Contents` lists the same stream.
 pub fn page_shapes(doc: &Document, page: usize) -> Shapes {
+    shapes_within(doc, page, &mut DecodeBudget::page())
+}
+
+/// [`page_shapes`], decoding against `budget`: a stream `/Contents` lists again is charged again,
+/// and one past what is left reads as empty.
+pub(crate) fn shapes_within(doc: &Document, page: usize, budget: &mut DecodeBudget) -> Shapes {
     let mut out = Shapes::default();
     let Some(p) = pdfcraft_model::pages(doc).into_iter().nth(page) else { return out };
     let list: Vec<Object> = match p.dict.get(b"Contents").map(|c| doc.resolve(c)) {
@@ -139,24 +201,36 @@ pub fn page_shapes(doc: &Document, page: usize) -> Shapes {
     let mut pieces = Vec::new();
     for o in list {
         if let Object::Stream(s) = &*doc.resolve(&o) {
-            pieces.push(s.decoded().unwrap_or_default());
+            pieces.push(budget.decode(s).unwrap_or_default());
         }
     }
     let mut ctm = Matrix::IDENTITY;
-    let mut stack = Vec::new();
+    let mut saves = Saves::default();
     let mut path_boxes: Vec<[f64; 4]> = Vec::new();
     let mut subpaths: Vec<DetectionPath> = Vec::new();
     let mut path = DetectionPath::default();
     let mut cur: Option<[f64; 2]> = None;
-    for op in Pieces::join(&pieces).parse().ops {
+    let joined = Pieces::join(&pieces);
+    drop(pieces);
+    // An operator at a time: dense content (`n n n …`) parsed whole holds about 80 bytes for each
+    // byte it decoded.
+    for op in pdfcraft_content::ops(joined.data()) {
         match op.op.as_slice() {
-            b"q" => stack.push(ctm),
-            b"Q" => ctm = stack.pop().unwrap_or(ctm),
+            b"q" => saves.save(ctm),
+            b"Q" => saves.restore(&mut ctm),
             b"cm" => {
                 if let Some(m) = op.nums::<6>() {
                     ctm = Matrix(m).then(&ctm);
+                    saves.moved();
                 }
             }
+            // Painted where the matrix isn't known: dropped, as `n` drops a path.
+            b"S" | b"s" | b"f" | b"F" | b"f*" | b"B" | b"B*" | b"b" | b"b*" if saves.unknown => {
+                path_boxes.clear();
+                subpaths.clear();
+                path = DetectionPath::default();
+                cur = None;
+            }
             b"re" => {
                 path.finish(&mut subpaths);
                 if let Some([x, y, w, h]) = op.nums::<4>() {

crates/forms/src/read.rs

@@ -192,11 +192,17 @@ fn actions_of(doc: &Document, d: &Dict, widgets: &[ObjRef], scripts: &mut Decode
     out
 }
 
-fn values_of(doc: &Document, o: Option<&Object>) -> Vec<String> {
+/// Text streams of field values (`/V`, `/DV`) one reading of the form may decode in all, however
+/// many fields name the same stream.
+pub(crate) const MAX_VALUE_BYTES: usize = 64 << 20;
+
+/// A field's value or default value (`/V`, `/DV`). A text stream is decoded against `budget`, and
+/// reads as no value once it is spent, as one that won't decode does.
+fn values_of(doc: &Document, o: Option<&Object>, budget: &mut DecodeBudget) -> Vec<String> {
     let Some(o) = o else { return Vec::new() };
     match &*doc.resolve(o) {
         Object::Array(a) => a.iter().filter_map(|x| text_of(&doc.resolve(x))).collect(),
-        Object::Stream(s) => s.decoded().ok().map(|b| PdfString::literal(b).to_text()).into_iter().collect(),
+        Object::Stream(s) => budget.decode(s).ok().map(|b| PdfString::literal(b).to_text()).into_iter().collect(),
         other => text_of(other).filter(|s| s != "Off" && !s.is_empty()).into_iter().collect(),
     }
 }
@@ -345,7 +351,12 @@ pub(crate) fn enumerate(doc: &Document) -> (Vec<Field>, usize) {
         None => Inherited::default(),
     };
     let mut out = Vec::new();
-    let mut seen = Seen { fields: std::collections::HashSet::new(), widgets: std::collections::HashSet::new(), scripts: script_budget() };
+    let mut seen = Seen {
+        fields: std::collections::HashSet::new(),
+        widgets: std::collections::HashSet::new(),
+        scripts: script_budget(),
+        values: DecodeBudget::new(MAX_VALUE_BYTES, 0),
+    };
     if let Some(af) = &af {
         for f in af.get(b"Fields").map(|o| doc.resolve(o)).and_then(|o| o.as_array().cloned()).unwrap_or_default() {
             if let Some(r) = f.as_ref() {
@@ -416,13 +427,14 @@ fn unlisted_root(doc: &Document, r: ObjRef, seen: &std::collections::HashSet<Obj
     }
 }
 
-/// What one reading of the form's fields has used: the field and widget dictionaries read, and
-/// the script budget their actions share.
+/// What one reading of the form's fields has used: the field and widget dictionaries read, the
+/// script budget their actions share, and the budget their value streams share.
 struct Seen {
     fields: std::collections::HashSet<ObjRef>,
     /// A widget belongs to the first field that lists it, however often it is listed.
     widgets: std::collections::HashSet<ObjRef>,
     scripts: DecodeBudget,
+    values: DecodeBudget,
 }
 
 /// Read the field at `r` and the fields under it into `out`, with what they inherit from
@@ -549,8 +561,8 @@ fn walk(
         name: inh.name.clone(),
         obj: r,
         kind,
-        value: values_of(doc, inh.v.as_ref()),
-        default: values_of(doc, inh.dv.as_ref()),
+        value: values_of(doc, inh.v.as_ref(), &mut seen.values),
+        default: values_of(doc, inh.dv.as_ref(), &mut seen.values),
         flags: ff,
         max_len: inh.max_len,
         options,

crates/forms/src/tests.rs

@@ -3575,6 +3575,149 @@ fn repeated_script_references_share_one_decode_budget() {
     assert!(calculate > 0 && calculate <= limit, "{calculate} bytes of field scripts");
 }
 
+/// An unfiltered stream of `body`, as an object of [`document`].
+fn raw_stream(body: &str) -> String {
+    format!("<< /Length {} >>\nstream\n{body}\nendstream", body.len())
+}
+
+/// 300 fields whose value is one 1 MiB text stream: a reading of the form decodes their values
+/// within one budget, not 300 MiB.
+#[test]
+fn repeated_value_streams_share_one_decode_budget() {
+    let fields_list: String = (0..300).map(|i| format!("{} 0 R ", i + 3)).collect();
+    let mut objs = vec![format!("<< /Type /Catalog /AcroForm << /Fields [{fields_list}] >> >>"), raw_stream(&"x".repeat(1 << 20))];
+    objs.extend((0..300).map(|i| format!("<< /FT /Tx /T (f{i}) /V 2 0 R /DV 2 0 R >>")));
+    let all = fields(&document(&objs));
+    assert_eq!(all.len(), 300);
+    let read: usize = all.iter().flat_map(|f| f.value.iter().chain(&f.default)).map(String::len).sum();
+    assert!(read > 0 && read <= crate::read::MAX_VALUE_BYTES, "{read} bytes of values");
+    assert_eq!(all[0].value, ["x".repeat(1 << 20)], "the first field still reads its value");
+}
+
+/// Clear form leaves a field as it is when its default is a stream the value budget didn't reach:
+/// 70 fields typed in, whose default is one 1 MiB text stream, keep a value, the first ones
+/// their default and the rest what was typed, none of them emptied.
+#[test]
+fn clear_form_keeps_a_field_whose_default_was_not_read() {
+    let n = 70;
+    let fields_list: String = (0..n).map(|i| format!("{} 0 R ", i + 3)).collect();
+    let mut objs = vec![format!("<< /Type /Catalog /AcroForm << /Fields [{fields_list}] >> >>"), raw_stream(&"d".repeat(1 << 20))];
+    objs.extend((0..n).map(|i| format!("<< /FT /Tx /T (f{i}) /V (typed) /DV 2 0 R >>")));
+    let mut doc = document(&objs);
+    reset(&mut doc, None).unwrap();
+    let values: Vec<String> = (0..n)
+        .map(|i| {
+            let field = doc.get(ObjRef::new(i as u32 + 3, 0));
+            field.as_dict().and_then(|d| d.get(b"V")).and_then(|v| v.as_string().map(PdfString::to_text)).unwrap_or_default()
+        })
+        .collect();
+    assert!(values.iter().all(|v| !v.is_empty()), "no field is emptied");
+    assert_eq!(values[0], "d".repeat(1 << 20), "the first field goes back to its default");
+    assert_eq!(values[n - 1], "typed", "the last field, whose default wasn't read, keeps its value");
+    // A value the reading didn't decode, with no default, is cleared: it isn't known to be empty.
+    let mut objs = vec![format!("<< /Type /Catalog /AcroForm << /Fields [{fields_list}] >> >>"), raw_stream(&"v".repeat(1 << 20))];
+    objs.extend((0..n).map(|i| format!("<< /FT /Tx /T (f{i}) /V 2 0 R >>")));
+    let mut doc = document(&objs);
+    reset(&mut doc, None).unwrap();
+    let last = doc.get(ObjRef::new(n as u32 + 2, 0));
+    assert!(last.as_dict().and_then(|d| d.get(b"V")).is_none_or(|v| !matches!(v, Object::Ref(_))), "the last field's unread value is cleared");
+}
+
+/// Renaming a field that 300 calculations read through one shared Calculate action, whose script
+/// is a 256 KiB stream, decodes and rewrites that action once, in place: every calculation reads
+/// the new name, and nothing is decoded or written 300 times.
+#[test]
+fn a_rename_rewrites_a_shared_calculation_once() {
+    let n = 300;
+    let refs = |from: usize| -> String { (from..from + n).map(|i| format!("{i} 0 R ")).collect() };
+    let js = format!("AFSimple_Calculate(\"SUM\", new Array (\"a\"));{}", " ".repeat(256 << 10));
+    let mut objs = vec![
+        "<< /Type /Catalog /Pages 2 0 R /AcroForm 4 0 R >>".into(),
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(),
+        format!("<< /Type /Page /Parent 2 0 R /Annots [5 0 R {}] >>", refs(8)),
+        format!("<< /Fields [5 0 R {}] /DA (/Helv 0 Tf 0 g) >>", refs(8)),
+        "<< /Type /Annot /Subtype /Widget /FT /Tx /T (a) /Rect [50 700 250 720] /P 3 0 R >>".into(),
+        "<< /S /JavaScript /JS 7 0 R >>".into(),
+        raw_stream(&js),
+    ];
+    objs.extend((0..n).map(|i| format!("<< /Type /Annot /Subtype /Widget /FT /Tx /T (c{i}) /Rect [50 10 250 30] /P 3 0 R /AA << /C 6 0 R >> >>")));
+    let mut doc = document(&objs);
+    set_props(&mut doc, "a", &FieldProps { name: Some("qty".into()), ..FieldProps::default() }).unwrap();
+    let action = ObjRef::new(6, 0);
+    let renamed = (8..8 + n).all(|i| {
+        let field = doc.get(ObjRef::new(i as u32, 0));
+        field.as_dict().and_then(|d| d.get(b"AA")).and_then(|aa| aa.as_dict()?.get(b"C")?.as_ref()) == Some(action)
+    });
+    assert!(renamed, "every calculation still names the one shared action");
+    let js = doc.get(action).as_dict().and_then(|d| d.get(b"JS")?.as_string().map(PdfString::to_text)).unwrap_or_default();
+    assert!(js.contains("\"qty\"") && !js.contains("\"a\""), "the shared action reads the new name");
+    assert!(js.len() <= MAX_SCRIPT_BYTES, "{} bytes written once", js.len());
+}
+
+/// A page whose `/Contents` lists one 1 MiB stream ten times is read within the budget given:
+/// pieces past it read as empty, so their rectangles aren't found.
+#[test]
+fn page_shapes_decode_a_repeated_content_stream_within_the_budget() {
+    let piece = format!("%{}\n10 10 20 20 re S\n", "x".repeat(1 << 20));
+    let doc = document(&[
+        "<< /Type /Catalog /Pages 2 0 R >>".into(),
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(),
+        format!("<< /Type /Page /Parent 2 0 R /Contents [{}] >>", "4 0 R ".repeat(10)),
+        raw_stream(&piece),
+    ]);
+    assert_eq!(crate::detect::page_shapes(&doc, 0).boxes.len(), 10, "one page's allowance reads them all");
+    let mut budget = DecodeBudget::new(4 << 20, 0);
+    let boxes = crate::detect::shapes_within(&doc, 0, &mut budget).boxes.len();
+    assert!((1..=4).contains(&boxes), "{boxes} rectangles read within 4 MiB");
+    assert_eq!(budget.remaining(), 0, "the budget is spent");
+}
+
+/// Field detection keeps at most 256 saved graphics states, and each `Q` still restores its own
+/// `q` past that: a scale set 300 saves deep is gone once they are all restored.
+#[test]
+fn page_shapes_restore_saves_past_the_cap() {
+    let content = format!("{} 2 0 0 2 0 0 cm {} 10 10 20 20 re S", "q ".repeat(300), "Q ".repeat(300));
+    let doc = document(&[
+        "<< /Type /Catalog /Pages 2 0 R >>".into(),
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(),
+        "<< /Type /Page /Parent 2 0 R /Contents 4 0 R >>".into(),
+        raw_stream(&content),
+    ]);
+    assert_eq!(crate::detect::page_shapes(&doc, 0).boxes, [[10.0, 10.0, 30.0, 30.0]]);
+    // A scale set past the cap and closed by its own `Q` leaves a matrix that can't be known until
+    // the last lost save closes: what is drawn in between isn't reported at the scaled place.
+    let content = format!("{} q 2 0 0 2 0 0 cm Q 10 10 20 20 re S {} 40 40 10 10 re S", "q ".repeat(257), "Q ".repeat(257));
+    let doc = document(&[
+        "<< /Type /Catalog /Pages 2 0 R >>".into(),
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(),
+        "<< /Type /Page /Parent 2 0 R /Contents 4 0 R >>".into(),
+        raw_stream(&content),
+    ]);
+    assert_eq!(crate::detect::page_shapes(&doc, 0).boxes, [[40.0, 40.0, 50.0, 50.0]]);
+}
+
+/// The PDF/A declaration is read from metadata each filter stage of which decodes within
+/// [`crate::appearances::MAX_XMP_BYTES`], as preflight decodes it: a field drawn with characters its
+/// font lacks decodes no more than that a stage.
+#[test]
+fn a_pdfa_declaration_is_read_from_metadata_within_its_cap() {
+    let declared = |xmp: String| declares_pdfa(&document(&["<< /Type /Catalog /Metadata 2 0 R >>".into(), raw_stream(&xmp)]));
+    let pdfa = |padding: usize| format!("<x:xmpmeta><pdfaid:part>2</pdfaid:part>{}</x:xmpmeta>", " ".repeat(padding));
+    assert!(declared(pdfa(1 << 20)));
+    assert!(!declared(pdfa(crate::appearances::MAX_XMP_BYTES)), "metadata past the cap declares nothing");
+    assert!(!declared("<x:xmpmeta><dc:title>pdfaid</dc:title></x:xmpmeta>".into()), "metadata without pdfaid:part declares nothing");
+    // 3.5 MiB stored as hex, then Flate: its stages decode 7 and 3.5 MiB, each within the cap.
+    let xmp = pdfa(7 << 19);
+    let hex: Vec<u8> = xmp.bytes().flat_map(|b| [b"0123456789ABCDEF"[usize::from(b >> 4)], b"0123456789ABCDEF"[usize::from(b & 15)]]).collect();
+    let mut stream = pdfcraft_cos::Stream::flate(pdfcraft_cos::Dict::new(), &hex);
+    stream.dict.set(b"Filter".to_vec(), Object::Array(vec![Object::name("FlateDecode"), Object::name("ASCIIHexDecode")]));
+    let mut doc = Document::new_empty();
+    let metadata = doc.add(Object::Stream(stream));
+    let catalog = doc.add(Object::Dict([(b"Metadata".to_vec(), Object::Ref(metadata))].into_iter().collect()));
+    doc.trailer_mut().set(b"Root".to_vec(), Object::Ref(catalog));
+    assert!(declares_pdfa(&doc), "metadata through a chain of filters declares PDF/A, as preflight decodes it");
+}
+
 /// A widget listed many times, by one field's `/Kids` or by a `/Kids` array several fields share,
 /// is read once: the first field to list it owns it.
 #[test]
@@ -5344,6 +5487,29 @@ fn sorting_keeps_which_of_two_items_with_one_export_value_is_selected() {
     assert_eq!(selection_indices(&doc, &list), Some(vec![2]));
 }
 
+#[test]
+fn clearing_a_kids_length_limit_does_not_bring_back_its_parents() {
+    let mut doc = fixture();
+    let city = field(&fields(&doc), "address.city").clone();
+    let parent = doc.get(city.obj).as_dict().unwrap().reference(b"Parent").unwrap();
+    doc.update_dict(parent, |d| d.set(b"MaxLen".to_vec(), Object::Int(3))).unwrap();
+    set_props(&mut doc, "address.city", &FieldProps { max_len: Some(Some(8)), ..FieldProps::default() }).unwrap();
+    assert_eq!(field(&fields(&doc), "address.city").max_len, Some(8));
+    set_props(&mut doc, "address.city", &FieldProps { max_len: Some(None), ..FieldProps::default() }).unwrap();
+    let mut doc = reopen(&doc);
+    let f = field(&fields(&doc), "address.city").clone();
+    assert_eq!(f.max_len, None, "no limit, not the parent's 3");
+    let own = doc.get(f.obj).as_dict().and_then(|d| d.get(b"MaxLen")).and_then(Object::as_int);
+    assert_eq!(own, Some(0), "the kid holds an explicit unlimited of its own");
+    set_value(&mut doc, "address.city", &FieldValue::Text("Absalom".into())).unwrap();
+    assert_eq!(field(&fields(&reopen(&doc)), "address.city").value, ["Absalom"], "not cut to 3 characters");
+    // Without a parent limit, clearing still removes the key.
+    set_props(&mut doc, "name", &FieldProps { max_len: Some(Some(4)), ..FieldProps::default() }).unwrap();
+    set_props(&mut doc, "name", &FieldProps { max_len: Some(None), ..FieldProps::default() }).unwrap();
+    let name = field(&fields(&doc), "name").clone();
+    assert!(doc.get(name.obj).as_dict().unwrap().get(b"MaxLen").is_none());
+}
+
 #[test]
 fn clearing_a_kids_default_does_not_bring_back_its_parents() {
     let mut doc = fixture();

crates/forms/src/values.rs

@@ -470,7 +470,9 @@ fn redraw(doc: &mut Document, f: &Field, values: &[String], scripts: &mut dyn Sc
 /// document that declares PDF/A, which forbids it: there the widget's mark
 /// (`pdfcraft_fonts::UNDRAWN_MARK`) is all, and the edit's report says the `?` shows everywhere.
 pub(crate) fn ask_viewers_to_redraw(doc: &mut Document) -> Result<(), FormError> {
-    if declares_pdfa(doc) || need_appearances(doc) {
+    // The form's own flag first: once it is set, the metadata needn't be decoded again for each
+    // field drawn after.
+    if need_appearances(doc) || declares_pdfa(doc) {
         return Ok(());
     }
     let Some(root) = doc.root() else { return Ok(()) };
@@ -625,6 +627,22 @@ pub fn clear_password_values(doc: &mut Document) -> Result<usize, FormError> {
     Ok(targets.len())
 }
 
+/// Whether `field`'s `key` (`/V` or `/DV`, its own or inherited) is a stream with data, which
+/// [`fields`] reads as empty once its value budget is spent.
+fn unread_stream(doc: &Document, field: ObjRef, key: &[u8]) -> bool {
+    let mut node = Some(field);
+    for _ in 0..64 {
+        let Some(r) = node else { break };
+        let obj = doc.get(r);
+        let Some(d) = obj.as_dict() else { break };
+        if let Some(value) = d.get(key) {
+            return matches!(&*doc.resolve(value), Object::Stream(s) if !s.raw.is_empty());
+        }
+        node = d.reference(b"Parent");
+    }
+    false
+}
+
 /// Acrobat's Clear form: every field (or the named ones) back to its default value.
 pub fn reset(doc: &mut Document, names: Option<&[String]>) -> Result<usize, FormError> {
     let all = fields(doc);
@@ -638,7 +656,11 @@ pub fn reset(doc: &mut Document, names: Option<&[String]>) -> Result<usize, Form
     }
     let mut changed = 0;
     for f in all.iter().filter(|f| names.is_none_or(|n| n.contains(&f.name))) {
-        if f.value == f.default {
+        // A default the reading didn't decode (its budget spent) is unknown, not empty: clearing
+        // the field to nothing would lose the value it should go back to. A value it didn't decode
+        // isn't known to be the default, so it is reset.
+        let unread = |key: &[u8], read: &[String]| read.is_empty() && unread_stream(doc, f.obj, key);
+        if unread(b"DV", &f.default) || (f.value == f.default && !unread(b"V", &f.value)) {
             continue;
         }
         let v = match f.kind {

crates/optimize/README.md

@@ -30,7 +30,9 @@ let report = optimize_with_progress(&mut doc, &settings, &mut |stage| keep_going
   threshold are resampled with a bicubic (Catmull-Rom) filter to a target resolution and
   stored as JPEG (Acrobat's quality steps) or ZIP; soft masks are resampled with their image. A
   stencil `/Mask` has its own resolution, so the picture changes under it and it stays as it is.
-  An image is replaced only if the result is smaller. Left alone by these colour and grey
+  An image is replaced only if the result is smaller. Images over 80 million pixels are left
+  alone by the image steps, here and below, whatever their settings (memory); Clean Up may still
+  Flate an unfiltered or LZW one. Left alone by these colour and grey
   settings: CMYK and other colour spaces, image masks, colour-key masks, decode arrays, more than 8 bits, JPEG 2000,
   JBIG2 and CCITT (black-and-white images, CCITT and JBIG2 among them, are below). A JPEG is read with
   its colour transform (an Adobe marker's, else `/ColorTransform`, ISO 32000-2 §7.4.8), so one
@@ -87,7 +89,15 @@ let report = optimize_with_progress(&mut doc, &settings, &mut |stage| keep_going
     alone when JBIG2 is asked for, is stored again as the compression asks when that is smaller (as JBIG2 symbols where
     its own coding is a generic region, say); a symbol-coded scan, averaged, loses its exact
     repeats and often comes out larger, and then stays as it is. A JBIG2 image stored again refers to no
-    `/JBIG2Globals`, and one whose page isn't its size (PdfCraft's
+    `/JBIG2Globals` of its own. With JBIG2 asked for, the images stored as JBIG2, up to 16 at a
+    time, then share one symbol dictionary in a new `/JBIG2Globals` stream, holding the marks found
+    in more than one of them: those that come out smaller that way, when together they save more
+    than it takes. Only images that redaction can store again without it share one: image masks
+    and DeviceGray images named directly, of at most 64 Mi pixels (redaction's limit,
+    `pdfcraft_cos::MAX_REDACTED_IMAGE_PIXELS`); others are coded alone.
+    Redacting one of them stores the others of its group again without it, so the group keeps that
+    to 15 images, and each image's decode reads the dictionary of 16 at most. A
+    JBIG2 image whose page isn't its size (PdfCraft's
     renderer draws the whole page into the image) is left alone. With Retain, a resampled image
     keeps its kind of compression (CCITT, JBIG2, or Flate) and nothing else changes; an image of
     more bits is then left to the grey or colour settings. Every change is kept only when it is
@@ -96,11 +106,12 @@ let report = optimize_with_progress(&mut doc, &settings, &mut |stage| keep_going
     space, decode array and `/Mask` stay, but for packed RGB, which becomes grey with one decode
     pair. Group 4 wins on scans, whose ragged edges defeat Flate; on clean computer-drawn 1-bit
     art Flate can be smaller. Not yet: inline images, an image's own `/SMask` or `/Mask`
-    image (only images drawn on a page are visited), and Group 4 for rows wider than 32,767
-    samples.
+    image (only images drawn on a page are visited), Group 4 for rows wider than 32,767
+    samples, and JBIG2 past 65,535 samples on a side, where the decoder stops (its 2^28 in all
+    is past the 80 million pixels above).
 
   - Lossless JBIG2 uses bounded generic-region encoding or exact-copy symbol dictionaries when
-    smaller. No lossy symbol substitution is used. Export, redaction and this step read JBIG2
+    smaller, a dictionary shared by up to 16 images when that is smaller still. No lossy symbol substitution is used. Export, redaction and this step read JBIG2
     images, with bounded shared globals. All of a run's images share one allowance of decoding
     (`pdfcraft_cos::ImageBudget`), filters, decoders and pixels alike, JPEG samples and merged
     pictures too: about

crates/optimize/src/images.rs

@@ -1117,12 +1117,23 @@ fn downsample_bits_checked(data: &[u8], w: u32, h: u32, nw: u32, nh: u32, dark_i
 ///   to be resampled, and so is JBIG2 alone when Group 4 is asked for; Group 3, Group 4 inside
 ///   another filter, and JBIG2 otherwise are stored again like any other. With `Retain`, a resampled image keeps its kind of compression (CCITT, JBIG2, or
 ///   Flate), and nothing else changes: an image of more bits stays as it is, for the grey or
-///   colour settings. A JBIG2 image stored again refers to no `/JBIG2Globals`.
+///   colour settings. A JBIG2 image stored again refers to no `/JBIG2Globals`; with `Jbig2`, [`share`]
+///   may then have a group of them share one.
 ///
 /// The samples keep their meaning, so the colour space, decode array and `/Mask` stay, but for
 /// black-and-white RGB, which becomes grey with one decode pair, and an indexed image's default
 /// decode array, which goes as the default at one bit.
-fn mono(doc: &Document, s: &Stream, ppi: f64, defaults: bool, settings: &MonoSettings, budget: &mut ImageBudget) -> Option<(Stream, bool)> {
+///
+/// Stored as JBIG2 with `Jbig2`, it comes with the 1-bit samples it was coded from, for [`share`]
+/// to code again with the run's other JBIG2 images.
+fn mono(
+    doc: &Document,
+    s: &Stream,
+    ppi: f64,
+    defaults: bool,
+    settings: &MonoSettings,
+    budget: &mut ImageBudget,
+) -> Option<(Stream, bool, Option<Vec<u8>>)> {
     let d = &s.dict;
     let downsample = settings.downsample && ppi.is_finite() && ppi > settings.above_ppi && settings.target_ppi > 0.0 && !d.contains(b"SMask");
     let retain = settings.compression == MonoCompression::Retain;
@@ -1206,7 +1217,106 @@ fn mono(doc: &Document, s: &Stream, ppi: f64, defaults: bool, settings: &MonoSet
     let flate = ((resampled || packed_from_more) && !(retain && (ccitt || jbig2))).then(|| Stream::flate(dict, &data));
     // Smaller as stored, counting the dictionary: a tiny image can lose by Group 4's parameters.
     let best = [g4, jbig, flate].into_iter().flatten().filter_map(|c| Some((crate::stored_len(&c)?, c))).min_by_key(|(len, _)| *len)?;
-    (best.0 < crate::stored_len(s)?).then_some((best.1, resampled))
+    let shareable = settings.compression == MonoCompression::Jbig2 && best.1.dict.name(b"Filter") == Some(b"JBIG2Decode");
+    (best.0 < crate::stored_len(s)?).then(|| (best.1, resampled, shareable.then_some(data)))
+}
+
+/// The most images that share one symbol dictionary ([`share`]). Redaction stores again every
+/// image that shares a redacted one's dictionary, and each image's decode reads all of it, so a
+/// group keeps both to that many; most of what sharing saves comes with the first few images.
+const SHARED_IMAGES: usize = 16;
+
+/// The most bytes of 1-bit samples a group holds: a group is coded before it would pass them
+/// ([`hold_in`]). An image that shares has at most [`SHARED_PIXELS`], and as its rows are whole
+/// bytes, at most that many bytes, which is this: one always fits a group with nothing in it.
+const SHARED_BYTES: usize = 64 << 20;
+
+/// What the globals cost as an object of their own besides their dictionary and data: `N 0 obj`,
+/// `stream`, `endstream` and `endobj`, a cross-reference entry, and an encrypted file's IV and
+/// padding. A group is shared only when it saves more than that as well.
+const NEW_OBJECT: usize = 96;
+
+/// Adds `image` to `group`, coding the group (`share`, which empties it) first when the image's
+/// samples would take it past `cap` bytes, and after when it has [`SHARED_IMAGES`].
+fn hold_in(group: &mut Vec<Held>, image: Held, cap: usize, mut share: impl FnMut(&mut Vec<Held>)) {
+    if group.iter().map(|h| h.bits.len()).fold(image.bits.len(), usize::saturating_add) > cap {
+        share(group);
+    }
+    group.push(image);
+    if group.len() == SHARED_IMAGES {
+        share(group);
+    }
+}
+
+/// The most pixels an image sharing a dictionary has: redaction's own limit on the images it
+/// stores again (see [`shares`]).
+const SHARED_PIXELS: u64 = pdfcraft_cos::MAX_REDACTED_IMAGE_PIXELS;
+
+/// Whether an image stored as JBIG2 (its dictionary `d`) may share a dictionary: only one that
+/// redaction can store again without it, an image mask or a DeviceGray image, named directly, of
+/// at most [`SHARED_PIXELS`]. Redacting one image of a group stores the others so, as the
+/// dictionary can hold the shapes of marks under the area, and refuses the redaction for one it
+/// can't; an image of another colour space, though redaction may take it, is coded alone.
+fn shares(d: &Dict) -> bool {
+    let side = |key: &[u8]| d.int(key).and_then(|v| u64::try_from(v).ok());
+    let within = side(b"Width").zip(side(b"Height")).is_some_and(|(w, h)| w.saturating_mul(h) <= SHARED_PIXELS);
+    within && (matches!(d.get(b"ImageMask"), Some(Object::Bool(true))) || d.name(b"ColorSpace") == Some(b"DeviceGray"))
+}
+
+/// An image the run stored as JBIG2, held to be stored again sharing a dictionary ([`share`]): its
+/// 1-bit samples, `width` × `height`.
+struct Held {
+    image: ObjRef,
+    bits: Vec<u8>,
+    width: u32,
+    height: u32,
+}
+
+/// Stores the images of `group`, each JBIG2 already, again sharing one symbol dictionary in a
+/// `/JBIG2Globals` stream ([`pdfcraft_filters::encode_jbig2_shared`]): those that come out smaller
+/// that way, if together they save more than the globals take. The others stay as they are, and
+/// so do all of them when that saves nothing. `report` counts the bytes as they end up, the globals
+/// included.
+fn share(doc: &mut Document, group: &mut Vec<Held>, report: &mut Report) {
+    let held = std::mem::take(group);
+    if held.len() < 2 {
+        return;
+    }
+    let images: Vec<(&[u8], u32, u32)> = held.iter().map(|h| (&h.bits[..], h.width, h.height)).collect();
+    let Ok(Some(shared)) = pdfcraft_filters::encode_jbig2_shared(&images) else { return };
+    let with_globals = |s: &Stream, coded: Vec<u8>, globals: ObjRef| {
+        let mut dict = s.dict.clone();
+        let mut parms = Dict::new();
+        parms.set(b"JBIG2Globals".to_vec(), Object::Ref(globals));
+        dict.set(b"DecodeParms".to_vec(), Object::Dict(parms));
+        Stream::from_raw(dict, coded)
+    };
+    // Weighed naming the globals with the longest reference there is: the real one is no longer.
+    let longest = ObjRef { num: u32::MAX, generation: u16::MAX };
+    let (mut chosen, mut saved) = (Vec::new(), 0usize);
+    for (h, coded) in held.iter().zip(shared.images) {
+        let Some(coded) = coded else { continue };
+        let object = doc.get(h.image);
+        let Object::Stream(alone) = &*object else { continue };
+        let shorter = crate::stored_len(alone).zip(crate::stored_len(&with_globals(alone, coded.clone(), longest))).filter(|(a, b)| b < a);
+        if let Some((before, after)) = shorter {
+            saved = saved.saturating_add(before - after);
+            chosen.push((h.image, coded));
+        }
+    }
+    let globals = Stream::from_raw(Dict::new(), shared.globals);
+    if chosen.is_empty() || crate::stored_len(&globals).is_none_or(|takes| saved <= takes.saturating_add(NEW_OBJECT)) {
+        return;
+    }
+    report.image_bytes_after = report.image_bytes_after.saturating_add(globals.raw.len());
+    let globals = doc.add(Object::Stream(globals));
+    for (image, coded) in chosen {
+        let object = doc.get(image);
+        let Object::Stream(alone) = &*object else { continue };
+        report.image_bytes_after = report.image_bytes_after.saturating_sub(alone.raw.len()).saturating_add(coded.len());
+        let new = with_globals(alone, coded, globals);
+        doc.set(image, Object::Stream(new));
+    }
 }
 
 /// One pass over the document's images, within `budget`. An image past it stays as it is, and is
@@ -1239,6 +1349,13 @@ pub(crate) fn run(
     refs.sort_by_key(|(r, _)| r.num);
     let total = refs.len();
     let mut jbig2 = false;
+    let mut group: Vec<Held> = Vec::new();
+    // Holds a JBIG2 image for `share`, which codes the group once it is full.
+    let mut hold = |doc: &mut Document, image: ObjRef, size: (Option<i64>, Option<i64>), bits: Option<Vec<u8>>, report: &mut Report| {
+        let side = |v: Option<i64>| v.and_then(|v| u32::try_from(v).ok());
+        let (Some(bits), Some(width), Some(height)) = (bits, side(size.0), side(size.1)) else { return };
+        hold_in(&mut group, Held { image, bits, width, height }, SHARED_BYTES, |group| share(doc, group, report));
+    };
     for (done, (r, ppi)) in refs.into_iter().enumerate() {
         if !progress(Stage::Images { done, total }) {
             return Err(OptimizeError::Cancelled);
@@ -1254,7 +1371,7 @@ pub(crate) fn run(
             Some(m) if packed_from_more => (Some(m), None),
             m => (None, m),
         };
-        if let Some((new, resampled)) = mono {
+        if let Some((new, resampled, bits)) = mono {
             report.image_bytes_before += s.raw.len();
             report.image_bytes_after += new.raw.len();
             if resampled {
@@ -1263,7 +1380,10 @@ pub(crate) fn run(
                 report.images_recompressed += 1;
             }
             jbig2 |= new.dict.name(b"Filter") == Some(b"JBIG2Decode");
+            let size = (new.dict.int(b"Width"), new.dict.int(b"Height"));
+            let bits = bits.filter(|_| shares(&new.dict));
             doc.set(r, Object::Stream(new));
+            hold(doc, r, size, bits, report);
             continue;
         }
         let n = s.dict.get(b"ColorSpace").and_then(|cs| components(doc, cs));
@@ -1278,10 +1398,10 @@ pub(crate) fn run(
             }),
         };
         let total = |new: &Stream, smask: Option<&(ObjRef, Stream)>| Some(crate::stored_len(new)?.saturating_add(smask_len(smask).unwrap_or(0)));
-        let packed_wins = packed.as_ref().is_some_and(|(p, _)| {
+        let packed_wins = packed.as_ref().is_some_and(|(p, _, _)| {
             processed.as_ref().is_none_or(|(new, smask)| total(p, None).zip(total(new, smask.as_ref())).is_some_and(|(a, b)| a <= b))
         });
-        if let Some((new, resampled)) = packed.filter(|_| packed_wins) {
+        if let Some((new, resampled, bits)) = packed.filter(|_| packed_wins) {
             jbig2 |= new.dict.name(b"Filter") == Some(b"JBIG2Decode");
             report.image_bytes_before += s.raw.len();
             report.image_bytes_after += new.raw.len();
@@ -1290,7 +1410,10 @@ pub(crate) fn run(
             } else {
                 report.images_recompressed += 1;
             }
+            let size = (new.dict.int(b"Width"), new.dict.int(b"Height"));
+            let bits = bits.filter(|_| shares(&new.dict));
             doc.set(r, Object::Stream(new));
+            hold(doc, r, size, bits, report);
             continue;
         }
         let Some((new, smask)) = processed else {
@@ -1311,6 +1434,7 @@ pub(crate) fn run(
             doc.set(mr, Object::Stream(m));
         }
     }
+    share(doc, &mut group, report);
     if !progress(Stage::Images { done: total, total }) {
         return Err(OptimizeError::Cancelled);
     }
@@ -1338,6 +1462,58 @@ fn at_least_pdf_1_4(doc: &mut Document) -> Result<(), OptimizeError> {
 mod dimension_tests {
     use super::*;
 
+    /// A group is coded before an image's samples would take it past its limit, and once it has
+    /// [`SHARED_IMAGES`]: with room for 10 bytes, images of 4 go two to a group, never three, and
+    /// with room for 8, two of 4 fill one exactly; one of exactly the limit joins a group with
+    /// nothing in it.
+    #[test]
+    fn a_group_is_coded_before_its_samples_would_pass_the_limit() {
+        let held = |bytes: usize| Held { image: ObjRef { num: 1, generation: 0 }, bits: vec![0; bytes], width: 8, height: 8 };
+        let mut coded: Vec<Vec<usize>> = Vec::new();
+        let mut group = Vec::new();
+        let mut code = |g: &mut Vec<Held>| coded.push(std::mem::take(g).iter().map(|h| h.bits.len()).collect());
+        for _ in 0..5 {
+            hold_in(&mut group, held(4), 10, &mut code);
+        }
+        hold_in(&mut group, held(10), 10, &mut code);
+        assert_eq!(coded, [vec![4, 4], vec![4, 4], vec![4]]);
+        assert_eq!(group.iter().map(|h| h.bits.len()).collect::<Vec<_>>(), [10]);
+        // Exactly the limit is within it: with room for 8, two images of 4 stay together.
+        let (mut count, mut group) = (0, Vec::new());
+        let mut code = |g: &mut Vec<Held>| count += std::mem::take(g).len();
+        hold_in(&mut group, held(4), 8, &mut code);
+        hold_in(&mut group, held(4), 8, &mut code);
+        assert_eq!((count, group.len()), (0, 2));
+        let (mut count, mut group) = (0, Vec::new());
+        for _ in 0..SHARED_IMAGES {
+            hold_in(&mut group, held(1), usize::MAX, |g| count += std::mem::take(g).len());
+        }
+        assert_eq!((count, group.len()), (SHARED_IMAGES, 0), "coded on the 16th");
+    }
+
+    /// Only what redaction can store again without the dictionary shares one: an image mask, or
+    /// DeviceGray named directly, of at most 2^26 pixels.
+    #[test]
+    fn only_what_redaction_can_store_again_shares_a_dictionary() {
+        let dict = |entries: Vec<(&str, Object)>| {
+            let mut d = Dict::new();
+            for (k, v) in entries {
+                d.set(k.as_bytes().to_vec(), v);
+            }
+            d
+        };
+        let sized = |w: i64, h: i64, cs: Object| dict(vec![("Width", Object::Int(w)), ("Height", Object::Int(h)), ("ColorSpace", cs)]);
+        assert!(shares(&sized(8192, 8192, Object::name("DeviceGray"))));
+        assert!(!shares(&sized(8192, 8193, Object::name("DeviceGray"))), "a row past 2^26 pixels");
+        assert!(shares(&dict(vec![("Width", Object::Int(8)), ("Height", Object::Int(8)), ("ImageMask", Object::Bool(true))])));
+        let device_n =
+            Object::Array(vec![Object::name("DeviceN"), Object::Array(vec![Object::name("Black")]), Object::name("DeviceGray"), Object::Null]);
+        assert!(!shares(&sized(8, 8, device_n)));
+        assert!(!shares(&sized(8, 8, Object::name("CalGray"))));
+        assert!(!shares(&sized(8, 8, Object::Ref(ObjRef { num: 3, generation: 0 }))), "a colour space by reference");
+        assert!(!shares(&dict(vec![("ColorSpace", Object::name("DeviceGray"))])), "no size");
+    }
+
     #[test]
     fn pixel_reader_rejects_hostile_dimensions_before_decoding() {
         for (width, height, channels) in [(-1, 1, 1), (0, 1, 1), (i64::from(u32::MAX) + 101, 1, 1), (80_000_001, 1, 1), (2, 2, usize::MAX)] {

crates/optimize/tests/optimize.rs

@@ -1951,8 +1951,17 @@ fn black_and_white_images_become_jbig2() {
     assert!(r.image_bytes_after < as_g4.image_bytes_after, "JBIG2 {} bytes, Group 4 {}", r.image_bytes_after, as_g4.image_bytes_after);
     let images: Vec<Stream> = image_refs(&jbig2).into_iter().map(|i| stream(&jbig2, i)).collect();
     assert_eq!(images.len(), 3);
+    // The same text three times: the grey image and the mask share one symbol dictionary, and the
+    // indexed image, which only those share, is coded alone.
+    let globals_of = |s: &Stream| s.dict.get(b"DecodeParms").and_then(Object::as_dict).map(|d| (d.len(), d.reference(b"JBIG2Globals")));
+    let is_indexed = |s: &Stream| s.dict.get(b"ColorSpace").and_then(Object::as_array).is_some();
+    let shared: Vec<_> = images.iter().filter(|s| !is_indexed(s)).map(globals_of).collect();
+    assert!(shared.len() == 2 && shared[0].is_some_and(|(n, g)| n == 1 && g.is_some()) && shared[0] == shared[1], "{shared:?}");
     for s in &images {
-        assert_eq!((s.dict.name(b"Filter"), s.dict.contains(b"DecodeParms")), (Some(&b"JBIG2Decode"[..]), false));
+        assert_eq!(s.dict.name(b"Filter"), Some(&b"JBIG2Decode"[..]));
+        if is_indexed(s) {
+            assert!(!s.dict.contains(b"DecodeParms"));
+        }
     }
     assert!(images.iter().any(|s| s.dict.get(b"Decode") == Some(&decode)), "the decode array stays");
     let indexed_kept =
@@ -1999,6 +2008,11 @@ fn a_catalog_version_given_by_reference_is_read() {
 /// `#` a 3 × 3 block, three columns apart with a wider gap between words, every copy of a letter
 /// the same to the pixel.
 fn rendered_text(w: u32, h: u32) -> Vec<u8> {
+    rendered_text_from(w, h, 0x2545_F491_4F6C_DD1D)
+}
+
+/// [`rendered_text`], its letters picked from `seed`, which isn't 0.
+fn rendered_text_from(w: u32, h: u32, mut seed: u64) -> Vec<u8> {
     const LETTERS: [&[&str]; 5] = [
         &["##", "##", "##", "##", "##", "##", "##", "##", "##", "##"],
         &["......", ".####.", "##..##", "##..##", "##..##", "##..##", ".####."],
@@ -2008,7 +2022,6 @@ fn rendered_text(w: u32, h: u32) -> Vec<u8> {
     ];
     let stride = (w as usize).div_ceil(8);
     let mut data = vec![0xFF; stride * h as usize];
-    let mut seed = 0x2545_F491_4F6C_DD1Du64;
     let mut next = move || {
         seed ^= seed << 13;
         seed ^= seed >> 7;
@@ -2053,9 +2066,194 @@ fn rendered_text_becomes_jbig2_symbols() {
     assert_eq!(s.dict.name(b"Filter"), Some(&b"JBIG2Decode"[..]));
     let generic = pdfcraft_filters::encode_jbig2_generic(&text, w, h).unwrap();
     assert!(s.raw.len() * 2 < generic.len(), "symbols {} bytes, generic {}", s.raw.len(), generic.len());
+    assert!(!s.dict.contains(b"DecodeParms"), "alone, it shares no dictionary");
     assert!(render(&doc) == before, "the page looks the same");
 }
 
+/// Page `index` of `doc`, saved and opened again, rendered at scale 1.
+fn render_page(doc: &Document, index: usize) -> Vec<u8> {
+    let bytes = write_full(doc, &SaveOptions::default()).unwrap();
+    let mut r = pdfcraft_render::PageRenderer::new(Arc::new(bytes), pdfcraft_render::RenderConfig::default());
+    let out = r.render(pdfcraft_render::RenderRequest { page: index, scale: 1.0, ..Default::default() });
+    assert!(out.error.is_none(), "{:?}", out.error);
+    out.rgba.to_vec()
+}
+
+/// Text in a font of 26 letters, about 10 pt at 300 dpi: each letter 32 rows of a run from a stem
+/// down its left side, of 2 to 24 pixels, every copy the same to the pixel; lines 44 rows apart,
+/// the letters picked from `seed`, which isn't 0.
+fn font_text(w: u32, h: u32, mut seed: u64) -> Vec<u8> {
+    let mut font_seed = 0x2545_F491_4F6C_DD1Du64;
+    let next = |seed: &mut u64| {
+        *seed ^= *seed << 13;
+        *seed ^= *seed >> 7;
+        *seed ^= *seed << 17;
+        *seed
+    };
+    let letters: Vec<Vec<usize>> = (0..26).map(|_| (0..16).map(|_| 1 + (next(&mut font_seed) % 12) as usize).collect()).collect();
+    let stride = (w as usize).div_ceil(8);
+    let mut data = vec![0xFF; stride * h as usize];
+    for top in (8..(h as usize).saturating_sub(40)).step_by(44) {
+        let mut x = 8;
+        while x + 32 < w as usize {
+            let letter = &letters[(next(&mut seed) % 26) as usize];
+            for (row, run) in letter.iter().enumerate() {
+                for y in [top + 2 * row, top + 2 * row + 1] {
+                    for px in x..x + 2 * run {
+                        data[y * stride + px / 8] &= !(0x80 >> (px % 8));
+                    }
+                }
+            }
+            x += 2 * letter.iter().max().unwrap() + 4 + if next(&mut seed) % 6 == 0 { 14 } else { 0 };
+        }
+    }
+    data
+}
+
+/// The `/JBIG2Globals` an image names in its `/DecodeParms`.
+fn globals_of(doc: &Document, image: ObjRef) -> Option<ObjRef> {
+    stream(doc, image).dict.get(b"DecodeParms")?.as_dict()?.reference(b"JBIG2Globals")
+}
+
+/// Pages of text in one font, each letter the same to the pixel on every page, stored as JBIG2
+/// share one symbol dictionary (`/JBIG2Globals`): together they take less than each page coded
+/// alone, and every page looks the same, the last one, whose crosses no other page has, placing
+/// them from a dictionary of its own beside the shared one. The report counts the bytes they
+/// take, the globals once.
+#[test]
+fn jbig2_pages_share_one_symbol_dictionary() {
+    let mut doc = Document::new_empty();
+    let (w, h) = (600u32, 480u32);
+    let stride = (w as usize).div_ceil(8);
+    let pages: Vec<Vec<u8>> = (1..=4u64)
+        .map(|k| {
+            let mut text = font_text(w, h, k.wrapping_mul(0x9E37_79B9_7F4A_7C15));
+            if k == 4 {
+                // Crosses down the right margin, three pixels a stroke.
+                for top in (40..440).step_by(40) {
+                    for (dx, dy) in (0..9).map(|i| (i, 4)).chain((0..9).map(|i| (4, i))) {
+                        let (x, y) = (580 + dx, top + dy);
+                        text[y * stride + x / 8] &= !(0x80 >> (x % 8));
+                    }
+                }
+            }
+            text
+        })
+        .collect();
+    let images: Vec<ObjRef> = pages
+        .iter()
+        .map(|text| {
+            let im = mono_image(&mut doc, w, h, text, None, &[("BitsPerComponent", 1.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+            page(&mut doc, &[("Im", im)], "q 600 0 0 480 6 300 cm /Im Do Q");
+            im
+        })
+        .collect();
+    let before: Vec<Vec<u8>> = (0..pages.len()).map(|p| render_page(&doc, p)).collect();
+    let alone: usize = pages.iter().map(|text| pdfcraft_filters::encode_jbig2(text, w, h).unwrap().len()).sum();
+    let settings = Settings { mono: MonoSettings { compression: MonoCompression::Jbig2, ..MonoSettings::REDUCE }, ..Settings::default() };
+    let report = optimize(&mut doc, &settings).unwrap();
+    let globals = globals_of(&doc, images[0]).expect("the first page names the globals");
+    assert!(images.iter().all(|im| globals_of(&doc, *im) == Some(globals)), "every page names the same globals");
+    let shared = stream(&doc, globals).raw.len() + images.iter().map(|im| stream(&doc, *im).raw.len()).sum::<usize>();
+    assert!(shared * 4 < alone * 3, "shared {shared} bytes, alone {alone}");
+    assert_eq!(report.image_bytes_after, shared);
+    for (p, before) in before.iter().enumerate() {
+        assert!(render_page(&doc, p) == *before, "page {p} looks the same");
+        let s = stream(&doc, images[p]);
+        assert_eq!(decoded_image(&doc, &s).unwrap(), pages[p], "page {p} decodes to its samples");
+    }
+    // Optimized again, each page would come out larger alone than it is beside the globals: the
+    // sharing stays.
+    let streams: Vec<Stream> = images.iter().map(|im| stream(&doc, *im)).collect();
+    let again = optimize(&mut doc, &settings).unwrap();
+    assert_eq!((again.images_recompressed, again.images_resampled), (0, 0));
+    assert!(images.iter().zip(&streams).all(|(im, s)| stream(&doc, *im) == *s));
+}
+
+/// Images share a dictionary only where that saves more than it takes: two pages of five small
+/// letters save less than their globals would take, and stay as they are coded alone.
+#[test]
+fn a_dictionary_that_saves_less_than_it_takes_isnt_shared() {
+    let mut doc = Document::new_empty();
+    let (w, h) = (600u32, 480u32);
+    let images: Vec<ObjRef> = (1..=2u64)
+        .map(|k| {
+            let text = rendered_text_from(w, h, k.wrapping_mul(0x9E37_79B9_7F4A_7C15));
+            let im = mono_image(&mut doc, w, h, &text, None, &[("BitsPerComponent", 1.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+            page(&mut doc, &[("Im", im)], "q 600 0 0 480 6 300 cm /Im Do Q");
+            im
+        })
+        .collect();
+    let settings = Settings { mono: MonoSettings { compression: MonoCompression::Jbig2, ..MonoSettings::REDUCE }, ..Settings::default() };
+    let report = optimize(&mut doc, &settings).unwrap();
+    assert_eq!(report.images_recompressed, 2);
+    for im in &images {
+        let s = stream(&doc, *im);
+        assert_eq!((s.dict.name(b"Filter"), s.dict.contains(b"DecodeParms")), (Some(&b"JBIG2Decode"[..]), false));
+    }
+    // Optimized again, they code to what they are, no smaller: they stay.
+    let streams: Vec<Stream> = images.iter().map(|im| stream(&doc, *im)).collect();
+    assert_eq!(optimize(&mut doc, &settings).unwrap().images_recompressed, 0);
+    assert!(images.iter().zip(&streams).all(|(im, s)| stream(&doc, *im) == *s));
+}
+
+/// Only JBIG2 asked for shares: under Retain, JBIG2 pages drawn at 600 ppi are averaged and stored
+/// as JBIG2 again, each alone, as Retain changes nothing but their resolution.
+#[test]
+fn retained_jbig2_shares_nothing() {
+    let mut doc = Document::new_empty();
+    let (w, h) = (1200u32, 960u32);
+    let images: Vec<ObjRef> = (1..=4u64)
+        .map(|k| {
+            let text = font_text(w, h, k.wrapping_mul(0x9E37_79B9_7F4A_7C15));
+            let mut d = Dict::new();
+            for (key, value) in [("Type", Object::name("XObject")), ("Subtype", Object::name("Image")), ("ColorSpace", Object::name("DeviceGray"))] {
+                d.set(key.as_bytes().to_vec(), value);
+            }
+            for (key, value) in [("Width", i64::from(w)), ("Height", i64::from(h)), ("BitsPerComponent", 1)] {
+                d.set(key.as_bytes().to_vec(), Object::Int(value));
+            }
+            d.set(b"Filter".to_vec(), Object::name("JBIG2Decode"));
+            let im = doc.add(Object::Stream(Stream::from_raw(d, pdfcraft_filters::encode_jbig2(&text, w, h).unwrap())));
+            // 1200 samples over 144 pt: 600 ppi.
+            page(&mut doc, &[("Im", im)], "q 144 0 0 115.2 6 300 cm /Im Do Q");
+            im
+        })
+        .collect();
+    let settings = Settings { mono: MonoSettings { compression: MonoCompression::Retain, ..MonoSettings::REDUCE }, ..Settings::default() };
+    assert_eq!(optimize(&mut doc, &settings).unwrap().images_resampled, 4);
+    for im in images {
+        let s = stream(&doc, im);
+        assert_eq!((s.dict.name(b"Filter"), s.dict.contains(b"DecodeParms")), (Some(&b"JBIG2Decode"[..]), false));
+    }
+}
+
+/// Sixteen images at most share one dictionary, and two are enough: of eighteen, the first
+/// sixteen share one and the other two another.
+#[test]
+fn sixteen_images_at_most_share_a_dictionary() {
+    let mut doc = Document::new_empty();
+    let (w, h) = (600u32, 480u32);
+    let texts: Vec<Vec<u8>> = (1..=18u64).map(|k| font_text(w, h, k.wrapping_mul(0x9E37_79B9_7F4A_7C15))).collect();
+    let images: Vec<ObjRef> = texts
+        .iter()
+        .map(|text| {
+            let im = mono_image(&mut doc, w, h, text, None, &[("BitsPerComponent", 1.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+            page(&mut doc, &[("Im", im)], "q 600 0 0 480 6 300 cm /Im Do Q");
+            im
+        })
+        .collect();
+    let settings = Settings { mono: MonoSettings { compression: MonoCompression::Jbig2, ..MonoSettings::REDUCE }, ..Settings::default() };
+    optimize(&mut doc, &settings).unwrap();
+    let globals: Vec<Option<ObjRef>> = images.iter().map(|im| globals_of(&doc, *im)).collect();
+    assert!(globals.iter().all(Option::is_some), "{globals:?}");
+    assert!(globals[..16].iter().all(|g| *g == globals[0]) && globals[16..].iter().all(|g| *g == globals[16]), "{globals:?}");
+    assert_ne!(globals[0], globals[16]);
+    for (k, (im, text)) in images.iter().zip(&texts).enumerate() {
+        assert!(decoded_image(&doc, &stream(&doc, *im)).unwrap() == *text, "image {k} decodes to its samples");
+    }
+}
+
 /// A JBIG2 scan goes through Monochrome Images like any black-and-white image. Above 450 ppi it
 /// is averaged as its Flate copy is, to the same samples, and stored as each compression asks:
 /// Group 4 or JBIG2, or Flate when that is smaller, or under Retain JBIG2 again; alone or behind another
@@ -3621,6 +3819,129 @@ fn indexed_thin_rules_survive_averaging_for_both_palette_orders_and_decodes() {
     }
 }
 
+/// An image past what the JBIG2 decoder takes on a side stays as it is: JBIG2 can state the size,
+/// but PdfCraft's decoder refuses such a stream, so stored as JBIG2 it drew nothing here. At 65,535
+/// on a side, the same bars do become JBIG2, so the fixture does reach that choice, and the coding
+/// stored (symbols, here) reads back through that decoder.
+#[test]
+fn an_image_too_large_for_the_jbig2_decoder_stays_as_it_is() {
+    for (w, h, stored) in
+        [(65_535u32, 16u32, &b"JBIG2Decode"[..]), (16, 65_535, b"JBIG2Decode"), (65_536, 16, b"FlateDecode"), (16, 65_536, b"FlateDecode")]
+    {
+        let mut doc = Document::new_empty();
+        let image = mono_image(&mut doc, w, h, &bars(w, h), None, &[("BitsPerComponent", 1.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+        page(&mut doc, &[("Im", image)], &format!("q {w} 0 0 {h} 0 0 cm /Im Do Q"));
+        let before = stream(&doc, image).raw.clone();
+        let settings =
+            Settings { mono: MonoSettings { compression: MonoCompression::Jbig2, downsample: false, ..MonoSettings::REDUCE }, ..Settings::default() };
+        optimize(&mut doc, &settings).unwrap();
+        let s = stream(&doc, image);
+        assert_eq!(s.dict.name(b"Filter"), Some(stored), "{w} × {h}");
+        if stored == b"FlateDecode" {
+            assert_eq!(s.raw, before, "{w} × {h}");
+        } else {
+            // The decoder gives padding bits as 0; the bars have them 1.
+            let mut bits = bars(w, h);
+            if w % 8 != 0 {
+                for row in bits.chunks_mut((w as usize).div_ceil(8)) {
+                    if let Some(last) = row.last_mut() {
+                        *last &= 0xFFu8 << (8 - w % 8);
+                    }
+                }
+            }
+            assert!(decoded_image(&doc, &s).unwrap() == bits, "{w} × {h} reads back");
+        }
+    }
+}
+
+/// The colour and grey steps leave an image over 80 million pixels as it is, whatever their settings
+/// (memory): 10,000 × 8,000 grey, the limit itself, drawn at 600 ppi, is resampled, and a row more
+/// stays as it is.
+#[test]
+fn grey_images_are_resampled_up_to_the_pixel_limit() {
+    for (h, resampled) in [(8_000u32, true), (8_001, false)] {
+        let mut doc = Document::new_empty();
+        let grey = image(&mut doc, 10_000, h, 1, false, None);
+        let before = stream(&doc, grey).raw.clone();
+        let (pw, ph) = (10_000.0 * 72.0 / 600.0, f64::from(h) * 72.0 / 600.0);
+        page(&mut doc, &[("G", grey)], &format!("q {pw} 0 0 {ph} 0 0 cm /G Do Q"));
+        let report = optimize(&mut doc, &Settings::default()).unwrap();
+        assert_eq!(report.images_resampled, usize::from(resampled), "10,000 × {h}: {report:?}");
+        let s = stream(&doc, grey);
+        if resampled {
+            assert_eq!(s.dict.int(b"Width"), Some(2_500), "10,000 × {h}");
+        } else {
+            assert!(s.dict.int(b"Width") == Some(10_000) && s.raw == before, "10,000 × {h} stays as it is");
+        }
+    }
+}
+
+/// Dark bars of irregular lengths across the long side of a `w` × `h` 1-bit image, which Flate
+/// shrinks less than JBIG2.
+fn bars(w: u32, h: u32) -> Vec<u8> {
+    let stride = (w as usize).div_ceil(8);
+    let mut data = vec![0xFF; stride * h as usize];
+    let mut state = 0x1234_5678u32;
+    let mut next = move || {
+        state ^= state << 13;
+        state ^= state >> 17;
+        state ^= state << 5;
+        state as usize
+    };
+    let long = w.max(h) as usize;
+    let mut at = 10;
+    while at + 60 < long {
+        let len = 5 + next() % 50;
+        for along in at..at + len {
+            for across in 0..12 {
+                let (x, y) = if w > h { (along, across) } else { (across, along) };
+                data[y * stride + x / 8] &= !(0x80 >> (x % 8));
+            }
+        }
+        at += len + 5 + next() % 50;
+    }
+    data
+}
+
+/// Past what the JBIG2 decoder takes on either side, an image packed from more bits, or one
+/// averaged to a size still past it, isn't stored as JBIG2 either: it becomes 1-bit Flate. Within
+/// the bound the same pictures do become JBIG2, so the fixtures reach that choice.
+#[test]
+fn what_is_too_large_for_jbig2_is_stored_another_way() {
+    let settings = |downsample| Settings {
+        mono: MonoSettings { compression: MonoCompression::Jbig2, downsample, ..MonoSettings::REDUCE },
+        ..Settings::default()
+    };
+    let (jbig2, flate) = (&b"JBIG2Decode"[..], &b"FlateDecode"[..]);
+    // Eight-bit grey of only black and white, packed to one bit first, wide and tall.
+    for (w, h, stored) in [(65_535u32, 16u32, jbig2), (65_536, 16, flate), (16, 65_535, jbig2), (16, 65_536, flate)] {
+        let (bits, stride) = (bars(w, h), (w as usize).div_ceil(8));
+        let grey: Vec<u8> = (0..h as usize)
+            .flat_map(|y| (0..w as usize).map(move |x| (y, x)))
+            .map(|(y, x)| if bits[y * stride + x / 8] & (0x80 >> (x % 8)) == 0 { 0 } else { 255 })
+            .collect();
+        let mut doc = Document::new_empty();
+        let image = mono_image(&mut doc, w, h, &grey, None, &[("BitsPerComponent", 8.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+        page(&mut doc, &[("Im", image)], &format!("q {w} 0 0 {h} 0 0 cm /Im Do Q"));
+        optimize(&mut doc, &settings(false)).unwrap();
+        let s = stream(&doc, image);
+        assert_eq!(s.dict.name(b"Filter"), Some(stored), "{w} × {h}, packed");
+        assert_eq!(s.dict.int(b"BitsPerComponent"), Some(1), "{w} × {h}, packed");
+    }
+    // One bit, drawn at 600 ppi and averaged to 300: half the size, so 140,000 is still past it.
+    for (w, h, stored) in [(70_000u32, 16u32, jbig2), (140_000, 16, flate), (16, 70_000, jbig2), (16, 140_000, flate)] {
+        let mut doc = Document::new_empty();
+        let image = mono_image(&mut doc, w, h, &bars(w, h), None, &[("BitsPerComponent", 1.into()), ("ColorSpace", Object::name("DeviceGray"))]);
+        let (pw, ph) = (f64::from(w) * 72.0 / 600.0, f64::from(h) * 72.0 / 600.0);
+        page(&mut doc, &[("Im", image)], &format!("q {pw} 0 0 {ph} 0 0 cm /Im Do Q"));
+        optimize(&mut doc, &settings(true)).unwrap();
+        let s = stream(&doc, image);
+        assert_eq!(s.dict.name(b"Filter"), Some(stored), "{w} × {h}, averaged");
+        assert_eq!(s.dict.int(b"BitsPerComponent"), Some(1), "{w} × {h}, averaged");
+        assert_eq!((s.dict.int(b"Width"), s.dict.int(b"Height")), (Some(i64::from(w / 2)), Some(i64::from(h / 2))), "{w} × {h}, averaged");
+    }
+}
+
 /// An indexed image also drawn where the optimizer doesn't read (an annotation's appearance, where
 /// other default colour spaces may be in force and change which palette entry is darker) keeps its
 /// resolution, as black-and-white RGB keeps its colour space; drawn only on the page, it is

crates/organize/src/lib.rs

@@ -20,6 +20,7 @@ mod dedupe;
 mod import;
 mod labels;
 mod outline;
+mod outline_io;
 mod pdfx;
 mod prune;
 mod transition;
@@ -40,6 +41,7 @@ pub use outline::{
     Bookmark, BookmarkPage, OutlineEntry, OutlineError, add_bookmark, add_bookmark_at, add_bookmark_tree, bookmark_page, bookmarks, delete_bookmark,
     move_bookmark, rename_bookmark, set_bookmark_color, set_bookmark_open, set_bookmark_page, set_bookmark_style, top_level_bookmarks,
 };
+pub use outline_io::{MAX_IMPORT_BOOKMARKS, OutlineNode, OutlineTree, import_outline, outline_tree, unmapped, view_arity};
 pub use transition::{TRANSITION_DIRECTIONS, TRANSITION_STYLES, Transition, TransitionSpec, set_transition};
 pub use view::{InitialView, displays_doc_title, initial_view, set_initial_view};
 

crates/organize/src/outline.rs

@@ -19,7 +19,7 @@ use crate::{OrganizeError, walk};
 
 /// Deepest level a listing enters (the top level is 0). Bookmarks deeper than this are not
 /// listed; edits still reach them by path.
-const LIST_DEPTH: usize = 32;
+pub(crate) const LIST_DEPTH: usize = 32;
 
 /// Deepest name-tree node read when looking up named destinations.
 const NAME_TREE_DEPTH: usize = 32;
@@ -72,6 +72,14 @@ pub enum OutlineError {
     BadColor,
     #[error("this document has no tagged headings to make bookmarks from")]
     NoEntries,
+    #[error("there are no bookmarks to add")]
+    NothingToImport,
+    #[error("the bookmark at {0:?} has a view that is not a known destination type with its values")]
+    BadView(Vec<usize>),
+    #[error("bookmarks may nest at most {0} levels deep")]
+    TooDeep(usize),
+    #[error("at most {0} bookmarks can be added at once")]
+    TooManyBookmarks(usize),
     #[error("{0}")]
     Organize(#[from] OrganizeError),
     #[error("{0}")]
@@ -449,7 +457,7 @@ impl From<OutlineError> for OrganizeError {
 
 /// Make `kids` the children of `parent`, in order: rewires `/Parent`, `/Prev`, `/Next`,
 /// `/First` and `/Last`.
-fn relink(doc: &mut Document, parent: ObjRef, kids: &[ObjRef]) -> Result<()> {
+pub(crate) fn relink(doc: &mut Document, parent: ObjRef, kids: &[ObjRef]) -> Result<()> {
     for (i, k) in kids.iter().enumerate() {
         put(doc, *k, b"Parent", Some(Object::Ref(parent)))?;
         put(doc, *k, b"Prev", i.checked_sub(1).map(|p| Object::Ref(kids[p])))?;
@@ -473,7 +481,7 @@ struct Counting {
 
 /// Recompute every `/Count` (§12.3.3: open items count their visible descendants, closed items
 /// the negative of what opening them would show; the root counts all visible items).
-fn recount(doc: &mut Document) -> Result<()> {
+pub(crate) fn recount(doc: &mut Document) -> Result<()> {
     let Some(root) = outline_root(doc) else { return Ok(()) };
     let mut seen = HashSet::from([root]);
     let kids = children_of(doc, root, &mut seen);
@@ -714,7 +722,7 @@ pub fn move_bookmark(doc: &mut Document, from: &[usize], to_parent: &[usize], in
 
 /// Open `parent` so a bookmark just added or moved into it shows (the root is always open).
 /// Only the sign of `/Count` matters here: [`recount`] sets its value.
-fn show_children(doc: &mut Document, parent: ObjRef, parent_path: &[usize]) -> Result<()> {
+pub(crate) fn show_children(doc: &mut Document, parent: ObjRef, parent_path: &[usize]) -> Result<()> {
     if !parent_path.is_empty() && doc.get(parent).as_dict().and_then(|d| d.int(b"Count")).is_none_or(|c| c <= 0) {
         put(doc, parent, b"Count", Some(Object::Int(1)))?;
     }

crates/organize/src/outline_io.rs

@@ -0,0 +1,261 @@
+//! Moving a whole outline (or one bookmark's subtree) out of a document and into another
+//! (ISO 32000-2 §12.3.3 outlines, §12.3.2.2 explicit destinations).
+//!
+//! [`outline_tree`] reads bookmarks as a portable tree of [`OutlineNode`]s: titles, nesting, open
+//! state, colour, style and destinations as page index plus view in the file's own user space,
+//! so writing a tree back with [`import_outline`] gives the same structure. A node whose page the
+//! target lacks keeps its place in the tree without a destination, and [`unmapped`] names it, so
+//! nothing is dropped silently. Not carried: actions other than a GoTo, named destinations (they
+//! travel resolved to their page), and structure links (`/SE`).
+
+use pdfcraft_cos::{Dict, Document, ObjRef, Object, PdfString};
+
+use crate::outline::{LIST_DEPTH, children, container, recount, relink, show_children};
+use crate::{OrganizeError, OutlineError, walk};
+
+/// Most bookmarks one import writes.
+pub const MAX_IMPORT_BOOKMARKS: usize = 100_000;
+
+/// The destination types (Table 149) and how many numbers follow each.
+const VIEWS: [(&[u8], usize); 8] = [(b"XYZ", 3), (b"Fit", 0), (b"FitH", 1), (b"FitV", 1), (b"FitR", 4), (b"FitB", 0), (b"FitBH", 1), (b"FitBV", 1)];
+
+/// One bookmark and the bookmarks under it, independent of any document.
+#[derive(Clone, Debug, PartialEq)]
+pub struct OutlineNode {
+    pub title: String,
+    /// The 0-based page it goes to; `None` for a bookmark that goes nowhere in its document.
+    pub page: Option<usize>,
+    /// Where on the page: a destination type from Table 149 and exactly as many values as that
+    /// type takes, in PDF user space (`None` keeps the reader's value). `None` goes to the page at
+    /// the reader's position and zoom.
+    pub view: Option<(Vec<u8>, Vec<Option<f64>>)>,
+    /// The title's colour (`/C`), each component from 0 to 1; `None` is the default black.
+    pub color: Option<[f32; 3]>,
+    pub italic: bool,
+    pub bold: bool,
+    /// Shown expanded, when it has children.
+    pub open: bool,
+    pub children: Vec<OutlineNode>,
+}
+
+/// The tree [`outline_tree`] read.
+#[derive(Clone, Debug, PartialEq)]
+pub struct OutlineTree {
+    pub nodes: Vec<OutlineNode>,
+    /// Bookmarks nested deeper than the listing reaches (32 levels) were left out.
+    pub truncated: bool,
+}
+
+/// The bookmark at `path` with everything under it, or the whole outline for `[]`.
+pub fn outline_tree(doc: &Document, path: &[usize]) -> Result<OutlineTree, OutlineError> {
+    // A whole outline's top level sits at depth 0; a subtree's root is the bookmark at `path`.
+    let base = path.len().max(1);
+    let mut truncated = false;
+    // The open nodes, outermost first, each with its depth.
+    let mut open: Vec<(usize, OutlineNode)> = Vec::new();
+    let mut roots = Vec::new();
+    for b in crate::bookmarks(doc).into_iter().filter(|b| b.path.starts_with(path) && !b.path.is_empty()) {
+        let depth = b.path.len().saturating_sub(base);
+        if b.path.len() > LIST_DEPTH && has_children(doc, b.obj) {
+            truncated = true;
+        }
+        while open.last().is_some_and(|(d, _)| *d >= depth) {
+            close(&mut open, &mut roots);
+        }
+        let view = b.view.and_then(|(kind, values)| portable_view(kind, values));
+        let node =
+            OutlineNode { title: b.title, page: b.page, view, color: b.color, italic: b.italic, bold: b.bold, open: b.open, children: Vec::new() };
+        open.push((depth, node));
+    }
+    while !open.is_empty() {
+        close(&mut open, &mut roots);
+    }
+    if !path.is_empty() && roots.is_empty() {
+        return Err(OutlineError::NoSuchBookmark(path.to_vec()));
+    }
+    Ok(OutlineTree { nodes: roots, truncated })
+}
+
+fn close(open: &mut Vec<(usize, OutlineNode)>, roots: &mut Vec<OutlineNode>) {
+    if let Some((_, node)) = open.pop() {
+        match open.last_mut() {
+            Some((_, parent)) => parent.children.push(node),
+            None => roots.push(node),
+        }
+    }
+}
+
+fn has_children(doc: &Document, r: ObjRef) -> bool {
+    doc.get(r).as_dict().is_some_and(|d| d.reference(b"First").is_some())
+}
+
+/// A destination's view as [`import_outline`] takes it: a known type with exactly its number of
+/// values (extra ones dropped, missing ones `None`). An unknown type, or a FitR missing one of
+/// its four values (the rectangle can't be kept), gives `None`.
+fn portable_view(kind: Vec<u8>, mut values: Vec<Option<f64>>) -> Option<(Vec<u8>, Vec<Option<f64>>)> {
+    let (_, arity) = VIEWS.iter().find(|(k, _)| *k == kind.as_slice())?;
+    values.resize(*arity, None);
+    if kind.as_slice() == b"FitR" && values.iter().any(Option::is_none) {
+        return None;
+    }
+    Some((kind, values))
+}
+
+/// The nodes of `nodes` whose page `page_count` pages don't have, as paths into `nodes`
+/// (0-based child indices), in tree order. [`import_outline`] keeps these without a destination.
+pub fn unmapped(nodes: &[OutlineNode], page_count: usize) -> Vec<Vec<usize>> {
+    let mut out = Vec::new();
+    visit(nodes, |path, node| {
+        if node.page.is_some_and(|p| p >= page_count) {
+            out.push(path.to_vec());
+        }
+    });
+    out
+}
+
+/// How many values a view of destination type `kind` takes (Table 149), or `None` for a type
+/// that is not one of them.
+pub fn view_arity(kind: &[u8]) -> Option<usize> {
+    VIEWS.iter().find(|(k, _)| *k == kind).map(|(_, arity)| *arity)
+}
+
+/// Call `f` with each node's path and the node, parents first. Iterative.
+fn visit<'a>(nodes: &'a [OutlineNode], mut f: impl FnMut(&[usize], &'a OutlineNode)) {
+    // One entry per open level: its nodes and how many of them have been visited.
+    let mut stack: Vec<(&'a [OutlineNode], usize)> = vec![(nodes, 0)];
+    // The visited node's path, kept in step with the stack rather than rebuilt per node.
+    let mut path: Vec<usize> = Vec::new();
+    while let Some(level) = stack.last_mut() {
+        let list = level.0;
+        let index = level.1;
+        let Some(node) = list.get(index) else {
+            stack.pop();
+            continue;
+        };
+        level.1 = index.saturating_add(1);
+        path.truncate(stack.len().saturating_sub(1));
+        path.push(index);
+        f(&path, node);
+        if !node.children.is_empty() {
+            stack.push((&node.children, 0));
+        }
+    }
+}
+
+/// Check every node before anything is written: depth (counting the `base` levels above the
+/// tree), count, colour and view.
+fn check(nodes: &[OutlineNode], base: usize) -> Result<(), OutlineError> {
+    let mut problem = None;
+    let mut count = 0usize;
+    visit(nodes, |path, node| {
+        count = count.saturating_add(1);
+        if problem.is_some() {
+            return;
+        }
+        if base.saturating_add(path.len()) > LIST_DEPTH.saturating_add(1) {
+            problem = Some(OutlineError::TooDeep(LIST_DEPTH.saturating_add(1)));
+        } else if node.color.is_some_and(|c| !c.iter().all(|v| (0.0..=1.0).contains(v))) {
+            problem = Some(OutlineError::BadColor);
+        } else if node.view.as_ref().is_some_and(|v| !view_is_valid(v)) {
+            problem = Some(OutlineError::BadView(path.to_vec()));
+        }
+    });
+    if count > MAX_IMPORT_BOOKMARKS {
+        return Err(OutlineError::TooManyBookmarks(MAX_IMPORT_BOOKMARKS));
+    }
+    problem.map_or(Ok(()), Err)
+}
+
+/// A known type with its number of values, each finite; `/FitR` needs all four.
+fn view_is_valid((kind, values): &(Vec<u8>, Vec<Option<f64>>)) -> bool {
+    VIEWS.iter().any(|(k, arity)| *k == kind.as_slice() && *arity == values.len())
+        && values.iter().flatten().all(|v| v.is_finite())
+        && (kind.as_slice() != b"FitR" || values.iter().all(Option::is_some))
+}
+
+/// Write `nodes` as children of the bookmark at `parent_path` (`[]` = top level), starting at
+/// child `index` (past the end appends), or, with `replace`, in place of the outline's
+/// top-level bookmarks (then `parent_path` must be `[]`). Nodes whose page this document lacks
+/// are written without a destination (see [`unmapped`]). Everything is checked before anything
+/// is written. Returns the path of the first node written.
+pub fn import_outline(
+    doc: &mut Document,
+    parent_path: &[usize],
+    index: usize,
+    nodes: &[OutlineNode],
+    replace: bool,
+) -> Result<Vec<usize>, OutlineError> {
+    if nodes.is_empty() {
+        return Err(OutlineError::NothingToImport);
+    }
+    if replace && !parent_path.is_empty() {
+        return Err(OrganizeError::Invalid("replace applies to the whole outline: leave the parent out".into()).into());
+    }
+    check(nodes, parent_path.len())?;
+    let pages: Vec<ObjRef> = walk(doc)?.into_iter().map(|(r, _)| r).collect();
+    let parent = container(doc, parent_path)?;
+    let top = write_nodes(doc, &pages, nodes)?;
+    let mut kids = if replace { Vec::new() } else { children(doc, parent) };
+    let at = index.min(kids.len());
+    kids.splice(at..at, top);
+    relink(doc, parent, &kids)?;
+    show_children(doc, parent, parent_path)?;
+    recount(doc)?;
+    let mut path = parent_path.to_vec();
+    path.push(at);
+    Ok(path)
+}
+
+/// Add one item per node, linked under each other, and return the top-level items in order.
+fn write_nodes(doc: &mut Document, pages: &[ObjRef], nodes: &[OutlineNode]) -> Result<Vec<ObjRef>, OutlineError> {
+    // Each written item with its node, then its children's items once they are written.
+    let mut written: Vec<(ObjRef, Vec<ObjRef>)> = Vec::new();
+    let mut top = Vec::new();
+    // (the nodes of one level, the next to write, the index in `written` of their parent)
+    let mut stack: Vec<(&[OutlineNode], usize, Option<usize>)> = vec![(nodes, 0, None)];
+    while let Some(level) = stack.last_mut() {
+        let (list, parent) = (level.0, level.2);
+        let Some(node) = list.get(level.1) else {
+            stack.pop();
+            continue;
+        };
+        level.1 = level.1.saturating_add(1);
+        let item = doc.add(Object::Dict(item_dict(node, pages)));
+        match parent.and_then(|p| written.get_mut(p)) {
+            Some((_, kids)) => kids.push(item),
+            None => top.push(item),
+        }
+        written.push((item, Vec::new()));
+        if !node.children.is_empty() {
+            stack.push((&node.children, 0, Some(written.len().saturating_sub(1))));
+        }
+    }
+    for (item, kids) in &written {
+        relink(doc, *item, kids)?;
+    }
+    Ok(top)
+}
+
+/// The item's own entries; the links and `/Count`'s value come from [`relink`] and [`recount`]
+/// (only the sign of the `/Count` written here matters: it keeps the open state).
+fn item_dict(node: &OutlineNode, pages: &[ObjRef]) -> Dict {
+    let mut d = Dict::new();
+    d.set(b"Title".to_vec(), Object::String(PdfString::text(&node.title)));
+    if let Some(page) = node.page.and_then(|p| pages.get(p)) {
+        let (kind, values) = node.view.clone().unwrap_or_else(|| (b"XYZ".to_vec(), vec![None; 3]));
+        let mut dest = vec![Object::Ref(*page), Object::Name(kind)];
+        dest.extend(values.into_iter().map(|v| v.map_or(Object::Null, Object::Real)));
+        d.set(b"Dest".to_vec(), Object::Array(dest));
+    }
+    if let Some(c) = node.color.filter(|c| *c != [0.0; 3]) {
+        d.set(b"C".to_vec(), Object::Array(c.iter().map(|v| Object::Real(f64::from(*v))).collect()));
+    }
+    let flags = i64::from(node.italic) | i64::from(node.bold) << 1;
+    if flags != 0 {
+        d.set(b"F".to_vec(), Object::Int(flags));
+    }
+    if !node.children.is_empty() {
+        d.set(b"Count".to_vec(), Object::Int(if node.open { 1 } else { -1 }));
+    }
+    d
+}

crates/organize/src/tests.rs

@@ -3813,3 +3813,175 @@ fn contents_pieces_join_with_a_space_across_a_trailing_comment() {
     ctrl_names.sort();
     assert_eq!(ctrl_names, [b"ImHidden".to_vec(), b"ImShown".to_vec()]);
 }
+
+/// Intro (closed, red bold, at a point) > [Part (italic, FitH), Figure (FitR)], then Results.
+fn outline_source() -> Document {
+    let mut d = doc_a();
+    crate::add_bookmark_at(&mut d, &[], 0, "Intro", 0, Some(20.0), Some(380.0)).unwrap();
+    crate::add_bookmark(&mut d, &[0], 0, "Part", 1).unwrap();
+    crate::add_bookmark(&mut d, &[0], 1, "Figure", 2).unwrap();
+    crate::add_bookmark(&mut d, &[], 1, "Results", 2).unwrap();
+    crate::set_bookmark_color(&mut d, &[0], Some([1.0, 0.0, 0.0])).unwrap();
+    crate::set_bookmark_style(&mut d, &[0], Some(true), None).unwrap();
+    crate::set_bookmark_style(&mut d, &[0, 0], None, Some(true)).unwrap();
+    let pages = crate::walk(&d).unwrap();
+    let (part, figure) = (crate::bookmarks(&d)[1].obj, crate::bookmarks(&d)[2].obj);
+    let dest = |p: usize, rest: Vec<Object>| Object::Array([vec![Object::Ref(pages[p].0)], rest].concat());
+    d.update_dict(part, |x| x.set(b"Dest".to_vec(), dest(1, vec![Object::name("FitH"), Object::Real(300.0)]))).unwrap();
+    let fit_r = vec![Object::name("FitR"), Object::Int(10), Object::Int(20), Object::Int(110), Object::Int(220)];
+    d.update_dict(figure, |x| x.set(b"Dest".to_vec(), dest(2, fit_r))).unwrap();
+    crate::set_bookmark_open(&mut d, &[0], false).unwrap();
+    d
+}
+
+fn node(title: &str, page: Option<usize>, children: Vec<crate::OutlineNode>) -> crate::OutlineNode {
+    crate::OutlineNode { title: title.into(), page, view: None, color: None, italic: false, bold: false, open: true, children }
+}
+
+/// The `/Prev`, `/Last` and `/Parent` links agree with `/First`–`/Next` at every level.
+fn assert_back_links(doc: &Document) {
+    let root = doc.get(doc.root().unwrap()).as_dict().unwrap().reference(b"Outlines").unwrap();
+    let mut stack = vec![root];
+    while let Some(parent) = stack.pop() {
+        let kids = crate::outline::children(doc, parent);
+        let d = doc.get(parent).as_dict().cloned().unwrap();
+        assert_eq!(d.reference(b"Last"), kids.last().copied());
+        for (i, k) in kids.iter().enumerate() {
+            let kd = doc.get(*k).as_dict().cloned().unwrap();
+            assert_eq!(kd.reference(b"Prev"), i.checked_sub(1).map(|p| kids[p]));
+            assert_eq!(kd.reference(b"Parent"), Some(parent));
+        }
+        stack.extend(kids);
+    }
+}
+
+#[test]
+fn an_exported_outline_imports_into_another_document_unchanged() {
+    let source = outline_source();
+    let tree = crate::outline_tree(&source, &[]).unwrap();
+    assert!(!tree.truncated);
+    let intro = &tree.nodes[0];
+    assert_eq!((intro.title.as_str(), intro.page, intro.open, intro.bold, intro.color), ("Intro", Some(0), false, true, Some([1.0, 0.0, 0.0])));
+    assert_eq!(intro.view, Some((b"XYZ".to_vec(), vec![Some(20.0), Some(380.0), None])));
+    assert_eq!(intro.children[0].view, Some((b"FitH".to_vec(), vec![Some(300.0)])));
+    assert!(intro.children[0].italic);
+    assert_eq!(intro.children[1].view, Some((b"FitR".to_vec(), vec![Some(10.0), Some(20.0), Some(110.0), Some(220.0)])));
+
+    let mut target = doc_a();
+    assert_eq!(crate::import_outline(&mut target, &[], 0, &tree.nodes, false).unwrap(), vec![0]);
+    assert_back_links(&target);
+    let back = full_roundtrip(&target);
+    assert_eq!(crate::outline_tree(&back, &[]).unwrap(), tree);
+    // The closed parent stays closed: its count is negative and the root counts only what shows.
+    let first = crate::bookmarks(&back)[0].obj;
+    let root = back.get(back.root().unwrap()).as_dict().unwrap().reference(b"Outlines").unwrap();
+    assert_eq!((count_of(&back, first), count_of(&back, root)), (Some(-2), Some(2)));
+}
+
+#[test]
+fn a_subtree_exports_alone_and_a_missing_path_is_refused() {
+    let source = outline_source();
+    let tree = crate::outline_tree(&source, &[0]).unwrap();
+    assert_eq!(tree.nodes.len(), 1);
+    assert_eq!(tree.nodes[0].title, "Intro");
+    assert_eq!(tree.nodes[0].children.iter().map(|n| n.title.as_str()).collect::<Vec<_>>(), ["Part", "Figure"]);
+    let leaf = crate::outline_tree(&source, &[0, 1]).unwrap();
+    assert_eq!((leaf.nodes.len(), leaf.nodes[0].title.as_str()), (1, "Figure"));
+    assert_eq!(crate::outline_tree(&source, &[5]), Err(crate::OutlineError::NoSuchBookmark(vec![5])));
+    assert_eq!(crate::outline_tree(&doc_a(), &[]).unwrap().nodes, []);
+}
+
+#[test]
+fn a_page_the_target_lacks_keeps_its_bookmark_without_a_destination() {
+    let tree = crate::outline_tree(&outline_source(), &[]).unwrap();
+    // doc_b has two pages: Figure and Results go to the third.
+    assert_eq!(crate::unmapped(&tree.nodes, 2), [vec![0, 1], vec![1]]);
+    let mut target = doc_b();
+    crate::import_outline(&mut target, &[], 0, &tree.nodes, false).unwrap();
+    let listed = crate::bookmarks(&target);
+    assert_eq!(titles(&listed), ["Intro[Part,Figure]", "Results"]);
+    assert_eq!(listed.iter().map(|b| b.page).collect::<Vec<_>>(), [Some(0), Some(1), None, None]);
+    assert!(target.get(listed[2].obj).as_dict().unwrap().get(b"Dest").is_none());
+}
+
+#[test]
+fn a_fit_r_missing_a_value_copies_with_its_page_and_no_view() {
+    let mut src = outline_source();
+    let pages = crate::walk(&src).unwrap();
+    let figure = crate::bookmarks(&src)[2].obj;
+    let short = vec![Object::Ref(pages[2].0), Object::name("FitR"), Object::Int(10), Object::Int(20), Object::Int(110)];
+    src.update_dict(figure, |x| x.set(b"Dest".to_vec(), Object::Array(short))).unwrap();
+    let tree = crate::outline_tree(&src, &[]).unwrap();
+    let copied = &tree.nodes[0].children[1];
+    assert_eq!((copied.page, copied.view.clone()), (Some(2), None));
+    let mut target = doc_a();
+    crate::import_outline(&mut target, &[], 0, &tree.nodes, false).unwrap();
+    assert_eq!(titles(&crate::bookmarks(&target)), ["Intro[Part,Figure]", "Results"]);
+}
+
+#[test]
+fn an_import_appends_inserts_or_replaces() {
+    let mut d = doc_a();
+    crate::add_bookmark(&mut d, &[], 0, "Old A", 0).unwrap();
+    crate::add_bookmark(&mut d, &[], 1, "Old B", 1).unwrap();
+    let new = [node("New", Some(2), vec![node("Child", Some(1), vec![])])];
+    assert_eq!(crate::import_outline(&mut d, &[], 1, &new, false).unwrap(), vec![1]);
+    assert_eq!(titles(&crate::bookmarks(&d)), ["Old A", "New[Child]", "Old B"]);
+    assert_eq!(crate::import_outline(&mut d, &[2], 9, &new, false).unwrap(), vec![2, 0]);
+    assert_eq!(titles(&crate::bookmarks(&d)), ["Old A", "New[Child]", "Old B[New[Child]]"]);
+    assert_back_links(&d);
+    assert_eq!(crate::import_outline(&mut d, &[], 5, &new, true).unwrap(), vec![0]);
+    assert_eq!(titles(&crate::bookmarks(&d)), ["New[Child]"]);
+    assert_back_links(&d);
+    let refused = crate::import_outline(&mut d, &[0], 0, &new, true);
+    assert!(matches!(refused, Err(crate::OutlineError::Organize(crate::OrganizeError::Invalid(_)))));
+    assert_eq!(crate::import_outline(&mut d, &[], 0, &[], false), Err(crate::OutlineError::NothingToImport));
+    assert_eq!(crate::import_outline(&mut d, &[7], 0, &new, false), Err(crate::OutlineError::NoSuchBookmark(vec![7])));
+}
+
+#[test]
+fn a_bad_node_anywhere_refuses_the_whole_import() {
+    let mut d = doc_a();
+    crate::add_bookmark(&mut d, &[], 0, "Kept", 0).unwrap();
+    let before = crate::bookmarks(&d);
+    let with = |f: &dyn Fn(&mut crate::OutlineNode)| {
+        let mut child = node("Child", Some(0), vec![]);
+        f(&mut child);
+        vec![node("Fine", Some(0), vec![]), node("Parent", Some(0), vec![child])]
+    };
+    let bad_views: [(&[u8], Vec<Option<f64>>); 4] =
+        [(b"XYZ", vec![Some(1.0)]), (b"Zoom", vec![]), (b"FitH", vec![Some(f64::NAN)]), (b"FitR", vec![Some(0.0), None, Some(1.0), Some(1.0)])];
+    for (kind, values) in bad_views {
+        let nodes = with(&|n| n.view = Some((kind.to_vec(), values.clone())));
+        assert_eq!(crate::import_outline(&mut d, &[], 0, &nodes, false), Err(crate::OutlineError::BadView(vec![1, 0])), "{kind:?}");
+    }
+    let nodes = with(&|n| n.color = Some([0.5, 1.5, 0.0]));
+    assert_eq!(crate::import_outline(&mut d, &[], 0, &nodes, false), Err(crate::OutlineError::BadColor));
+    let nodes = with(&|n| n.color = Some([f32::NAN, 0.0, 0.0]));
+    assert_eq!(crate::import_outline(&mut d, &[], 0, &nodes, false), Err(crate::OutlineError::BadColor));
+    let mut deep = node("Leaf", None, vec![]);
+    for _ in 0..33 {
+        deep = node("Level", None, vec![deep]);
+    }
+    assert_eq!(crate::import_outline(&mut d, &[], 0, &[deep], false), Err(crate::OutlineError::TooDeep(33)));
+    // 33 levels fit at the top, but not under a bookmark: the deepest would be past the listing.
+    let mut chain = node("Leaf", None, vec![]);
+    for _ in 0..32 {
+        chain = node("Level", None, vec![chain]);
+    }
+    assert_eq!(crate::import_outline(&mut d, &[0], 0, std::slice::from_ref(&chain), false), Err(crate::OutlineError::TooDeep(33)));
+    let many = vec![node("Item", None, vec![]); crate::MAX_IMPORT_BOOKMARKS + 1];
+    assert_eq!(crate::import_outline(&mut d, &[], 0, &many, false), Err(crate::OutlineError::TooManyBookmarks(crate::MAX_IMPORT_BOOKMARKS)));
+    assert_eq!(crate::bookmarks(&d), before);
+}
+
+#[test]
+fn an_outline_deeper_than_the_listing_is_exported_as_truncated() {
+    let tree = crate::outline_tree(&open(deep_outline(40)), &[]).unwrap();
+    assert!(tree.truncated);
+    assert!(!crate::outline_tree(&open(deep_outline(33)), &[]).unwrap().truncated);
+    // What was exported imports back: 33 levels is the deepest an import takes.
+    let mut target = doc_a();
+    crate::import_outline(&mut target, &[], 0, &tree.nodes, false).unwrap();
+    assert_eq!(crate::bookmarks(&target).len(), 33);
+}

crates/redact/src/image.rs

@@ -10,8 +10,9 @@
 use pdfcraft_content::{Matrix, overlaps};
 use pdfcraft_cos::{Dict, Document, ImageBudget, Object, Stream};
 
-/// Most pixels an image may have to be cleared in place (larger ones are removed).
-const MAX_PIXELS: u64 = 64 << 20;
+/// Most pixels an image may have to be cleared in place (larger ones are removed), or to be stored
+/// again without shared `/JBIG2Globals` (see [`without_globals`]).
+const MAX_PIXELS: u64 = pdfcraft_cos::MAX_REDACTED_IMAGE_PIXELS;
 
 fn components(doc: &Document, s: &Stream) -> Option<usize> {
     let cs = doc.resolve(s.dict.get(b"ColorSpace")?);

crates/render/src/raster/tests.rs

@@ -8756,6 +8756,9 @@ mod default_colour_spaces;
 // (vendored hayro-syntax patch 28, hayro-interpret patch 55).
 mod devicen_inks;
 
+// #5430: PNG-predicted Flate images are undone byte by byte (vendored hayro-syntax patch 35).
+mod png_predicted_images;
+
 // #3776: isolated DeviceCMYK groups blend in CMYK (vendored hayro-interpret patch 70, hayro
 // patch 27).
 mod isolated_cmyk_groups;
@@ -9127,3 +9130,271 @@ fn content_after_an_inline_image_holding_ei_is_still_read() {
     // `EI` inside the data was not taken for the end.
     assert!(page.contains("AFTER"), "the content after the image was lost: {page:?}");
 }
+
+/// `/Crypt` has nothing to undo, so a chain naming it thousands of times costs no copy of the data
+/// for each. A chain of filters that does work has its own cost, which this isn't about.
+#[test]
+fn a_long_chain_of_crypt_filters_takes_no_time() {
+    use super::*;
+    let content = format!("1 0 0 rg 0 0 200 200 re f\n{}", " ".repeat(16 << 20));
+    let chain = "/Crypt ".repeat(100_000);
+    let pdf = format!(
+        "%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n\
+             2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj\n\
+             3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] /Contents 4 0 R >> endobj\n\
+             4 0 obj << /Filter [{chain}] /Length {} >> stream\n{content}\nendstream endobj\n\
+             trailer << /Root 1 0 R >>\n%%EOF",
+        content.len()
+    );
+    let (done, finished) = std::sync::mpsc::channel();
+    std::thread::spawn(move || {
+        let page = PageRenderer::new(Arc::new(pdf.into_bytes()), RenderConfig::default()).render(RenderRequest {
+            page: 0,
+            kind: RequestKind::Pixels,
+            tile: None,
+            scale: 1.0,
+            tag: 0,
+            preview: false,
+        });
+        let start = (100 * page.width as usize + 100) * 4;
+        let _ = done.send(page.rgba.get(start..start + 4).map(<[u8]>::to_vec));
+    });
+    // Skipped, this takes a moment; copied, 1.6 TB, which a margin this wide tells apart however
+    // busy the machine.
+    let pixel = finished.recv_timeout(std::time::Duration::from_secs(120)).expect("the chain costs no copy for each entry");
+    assert_eq!(pixel, Some(vec![255, 0, 0, 255]));
+}
+
+/// A lone filter takes its parameters as a dictionary or as an array of one, and given as an array
+/// of one itself it takes either too. The form of `/Filter` decided which was read, so a predictor
+/// in the other form was lost and the content came out as noise. `/StmF` and `/StrF` are optional,
+/// meaning `/Identity`: such a file didn't open at all, though a stream can still name a filter.
+#[test]
+fn a_filters_parameters_are_read_in_either_form() {
+    use super::*;
+    use pdfcraft_cos::{Algorithm, Dict, Document, NewEncryption, Object, SaveOptions, Stream, write_full, write_incremental};
+    let content = b"1 0 0 rg 0 0 200 200 re f";
+    let centre = |bytes: Vec<u8>| -> [u8; 4] {
+        let page = PageRenderer::new(Arc::new(bytes), RenderConfig::default()).render(RenderRequest {
+            page: 0,
+            kind: RequestKind::Pixels,
+            tile: None,
+            scale: 1.0,
+            tag: 0,
+            preview: false,
+        });
+        let start = (100 * page.width as usize + 100) * 4;
+        let mut pixel = [0; 4];
+        pixel.copy_from_slice(page.rgba.get(start..start + 4).expect("centre pixel"));
+        pixel
+    };
+    let page = |stream: &[u8]| {
+        let mut pdf = b"%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj\n3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] /Contents 4 0 R >> endobj\n".to_vec();
+        pdf.extend_from_slice(stream);
+        pdf.extend_from_slice(b"\ntrailer << /Root 1 0 R >>\n%%EOF\n");
+        pdf
+    };
+    // PNG Sub over one row, which reads as noise if it isn't undone.
+    let mut rows = vec![1u8];
+    let mut before = 0u8;
+    for b in content {
+        rows.push(b.wrapping_sub(before));
+        before = *b;
+    }
+    let coded = Stream::flate(Dict::new(), &rows).raw;
+    let parms = format!("<< /Predictor 11 /Columns {} >>", content.len());
+    for (filter, decode_parms) in [
+        ("/FlateDecode", parms.clone()),
+        ("/FlateDecode", format!("[{parms}]")),
+        ("[/FlateDecode]", parms.clone()),
+        ("[/FlateDecode]", format!("[{parms}]")),
+    ] {
+        let mut stream = format!("4 0 obj << /Filter {filter} /DecodeParms {decode_parms} /Length {} >> stream\n", coded.len()).into_bytes();
+        stream.extend_from_slice(&coded);
+        stream.extend_from_slice(b"\nendstream endobj");
+        assert_eq!(centre(page(&stream)), [255, 0, 0, 255], "{filter} with {decode_parms}");
+    }
+
+    let plain = format!("4 0 obj << /Length {} >> stream\n{}\nendstream endobj", content.len(), String::from_utf8_lossy(content));
+    let mut doc = Document::open(Arc::new(page(plain.as_bytes()))).unwrap();
+    doc.set_encryption(&NewEncryption {
+        algorithm: Algorithm::Aes128,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -1,
+        encrypt_metadata: true,
+        seed: [9; 32],
+    })
+    .unwrap();
+    // No object streams: they would be encrypted under the /StmF about to go.
+    let saved = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
+    let mut doc = Document::open(Arc::new(saved)).unwrap();
+    let encrypt = doc.trailer().reference(b"Encrypt").unwrap();
+    doc.update_dict(encrypt, |e| {
+        e.remove(b"StmF");
+        e.remove(b"StrF");
+    })
+    .unwrap();
+    let mut doc = Document::open(Arc::new(write_incremental(&doc, &SaveOptions::default()).unwrap())).unwrap();
+    let catalog = doc.get(doc.root().unwrap());
+    let pages = doc.get(catalog.as_dict().unwrap().reference(b"Pages").unwrap());
+    let first = doc.resolve(&pages.as_dict().unwrap().get(b"Kids").unwrap().as_array().unwrap()[0]);
+    let contents = first.as_dict().unwrap().reference(b"Contents").unwrap();
+    let mut named = Dict::new();
+    named.set(b"Name".to_vec(), Object::name("StdCF"));
+    let mut dict = Dict::new();
+    dict.set(b"Filter".to_vec(), Object::name("Crypt"));
+    dict.set(b"DecodeParms".to_vec(), Object::Dict(named));
+    doc.set(contents, Object::Stream(Stream::from_raw(dict, content.to_vec())));
+    assert_eq!(centre(write_incremental(&doc, &SaveOptions::default()).unwrap()), [255, 0, 0, 255], "no /StmF, and a stream naming StdCF");
+}
+
+/// A stream can pick its own crypt filter: `/Crypt` in `/Filter`, with the filter's name in
+/// `/DecodeParms`, or `/Identity` without one (ISO 32000-2 §7.4.10). The renderer used the
+/// document's filter for every stream, and then couldn't decode `/Crypt`, so the page stayed blank.
+#[test]
+fn a_stream_with_a_crypt_filter_of_its_own_is_drawn() {
+    use super::*;
+    use pdfcraft_cos::{Algorithm, Dict, Document, NewEncryption, Object, SaveOptions, Stream, write_full, write_incremental};
+    let content = "1 0 0 rg 0 0 200 200 re f";
+    let page = format!(
+        "%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n\
+             2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj\n\
+             3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] /Contents 4 0 R >> endobj\n\
+             4 0 obj << /Length {} >> stream\n{content}\nendstream endobj\n\
+             trailer << /Root 1 0 R >>\n%%EOF",
+        content.len()
+    );
+    let centre = |bytes: Vec<u8>| -> [u8; 4] {
+        let page = PageRenderer::new(Arc::new(bytes), RenderConfig::default()).render(RenderRequest {
+            page: 0,
+            kind: RequestKind::Pixels,
+            tile: None,
+            scale: 1.0,
+            tag: 0,
+            preview: false,
+        });
+        let start = (100 * page.width as usize + 100) * 4;
+        let mut pixel = [0; 4];
+        pixel.copy_from_slice(page.rgba.get(start..start + 4).expect("centre pixel"));
+        pixel
+    };
+    let name = |n: &str| {
+        let mut parms = Dict::new();
+        parms.set(b"Name".to_vec(), Object::name(n));
+        Object::Dict(parms)
+    };
+    let hex: String = content.bytes().map(|b| format!("{b:02X}")).chain([">".to_string()]).collect();
+    let crypt = || Object::name("Crypt");
+    let contents_of = |doc: &Document| {
+        let catalog = doc.get(doc.root().unwrap());
+        let pages = doc.get(catalog.as_dict().unwrap().reference(b"Pages").unwrap());
+        let page = doc.resolve(&pages.as_dict().unwrap().get(b"Kids").unwrap().as_array().unwrap()[0]);
+        page.as_dict().unwrap().reference(b"Contents").unwrap()
+    };
+    for (algorithm, filters) in [(Algorithm::Rc4_128, false), (Algorithm::Aes128, true), (Algorithm::Aes256, true)] {
+        let mut doc = Document::open(Arc::new(page.clone().into_bytes())).unwrap();
+        doc.set_encryption(&NewEncryption {
+            algorithm,
+            user_password: "",
+            owner_password: "owner",
+            permissions: -1,
+            encrypt_metadata: true,
+            seed: [9; 32],
+        })
+        .unwrap();
+        let protected = write_full(&doc, &SaveOptions::default()).unwrap();
+        assert_eq!(centre(protected.clone()), [255, 0, 0, 255], "{algorithm:?}: the document's own filter");
+        // A filter of its own name that stores streams as they are, beside the document's.
+        let mut doc = Document::open(Arc::new(protected)).unwrap();
+        if filters {
+            let encrypt = doc.trailer().reference(b"Encrypt").unwrap();
+            doc.update_dict(encrypt, |e| {
+                let Some(Object::Dict(cf)) = e.get(b"CF") else { panic!("no /CF") };
+                let mut cf = cf.clone();
+                let mut stored = Dict::new();
+                stored.set(b"CFM".to_vec(), Object::name("None"));
+                cf.set(b"Stored".to_vec(), Object::Dict(stored));
+                // `/Identity` is never one of these, whatever a file says.
+                let mut named = Dict::new();
+                named.set(b"CFM".to_vec(), Object::name("AESV2"));
+                cf.set(b"Identity".to_vec(), Object::Dict(named));
+                e.set(b"CF".to_vec(), Object::Dict(cf));
+            })
+            .unwrap();
+        }
+        let protected = write_incremental(&doc, &SaveOptions::default()).unwrap();
+        let spellings = [
+            "no name",
+            "/Identity",
+            "StdCF",
+            "Stored",
+            "/DecodeParms by reference",
+            "/Filter by reference",
+            "an entry of /Filter by reference",
+            "an entry of /DecodeParms by reference",
+            "/Name by reference",
+            "before another filter",
+            "a lone dictionary for an array of one",
+            "an array of one for a name",
+            "a dictionary by reference for an array of one",
+            "an array of one by reference for a dictionary",
+            "a name by reference for an array",
+            "a lone dictionary before another filter",
+            "past the longest chain",
+        ];
+        for what in spellings {
+            let mut doc = Document::open(Arc::new(protected.clone())).unwrap();
+            let (filter, parms) = match what {
+                "no name" => (crypt(), None),
+                "/Identity" => (crypt(), Some(name("Identity"))),
+                "StdCF" => (crypt(), Some(name("StdCF"))),
+                "Stored" => (crypt(), Some(name("Stored"))),
+                "/DecodeParms by reference" => (crypt(), Some(Object::Ref(doc.add(name("StdCF"))))),
+                "/Filter by reference" => (Object::Ref(doc.add(crypt())), Some(name("StdCF"))),
+                "an entry of /Filter by reference" => (Object::Array(vec![Object::Ref(doc.add(crypt()))]), Some(Object::Array(vec![name("StdCF")]))),
+                "an entry of /DecodeParms by reference" => {
+                    (Object::Array(vec![crypt()]), Some(Object::Array(vec![Object::Ref(doc.add(name("StdCF")))])))
+                }
+                "/Name by reference" => {
+                    let mut parms = Dict::new();
+                    parms.set(b"Name".to_vec(), Object::Ref(doc.add(Object::name("StdCF"))));
+                    (crypt(), Some(Object::Dict(parms)))
+                }
+                "a lone dictionary for an array of one" => (Object::Array(vec![crypt()]), Some(name("StdCF"))),
+                "an array of one for a name" => (crypt(), Some(Object::Array(vec![name("StdCF")]))),
+                "a dictionary by reference for an array of one" => (Object::Array(vec![crypt()]), Some(Object::Ref(doc.add(name("StdCF"))))),
+                "an array of one by reference for a dictionary" => (Object::Ref(doc.add(Object::Array(vec![crypt()]))), Some(name("StdCF"))),
+                "a name by reference for an array" => (Object::Ref(doc.add(crypt())), Some(Object::Array(vec![name("StdCF")]))),
+                "a lone dictionary before another filter" => (Object::Array(vec![crypt(), Object::name("ASCIIHexDecode")]), Some(name("StdCF"))),
+                // One filter more than cos decodes: it names none there, so here neither, and the
+                // stream is read with the document's filter, not the `Stored` it says.
+                "past the longest chain" => {
+                    let mut chain = vec![crypt()];
+                    chain.extend(std::iter::repeat_n(Object::name("ASCIIHexDecode"), 9));
+                    (Object::Array(chain), Some(Object::Array(vec![name("Stored")])))
+                }
+                _ => (Object::Array(vec![crypt(), Object::name("ASCIIHexDecode")]), Some(Object::Array(vec![name("StdCF"), Object::Null]))),
+            };
+            let contents = contents_of(&doc);
+            let Object::Stream(s) = doc.get(contents).as_ref().clone() else { panic!("no content stream") };
+            let mut dict = s.dict.clone();
+            dict.set(b"Filter".to_vec(), filter);
+            if let Some(parms) = parms {
+                dict.set(b"DecodeParms".to_vec(), parms);
+            }
+            let raw = match what {
+                "before another filter" | "a lone dictionary before another filter" => hex.clone().into_bytes(),
+                "past the longest chain" => (0..9).fold(content.as_bytes().to_vec(), |data, _| {
+                    let mut coded: Vec<u8> = data.iter().flat_map(|b| format!("{b:02X}").into_bytes()).collect();
+                    coded.push(b'>');
+                    coded
+                }),
+                _ => content.as_bytes().to_vec(),
+            };
+            doc.set(contents, Object::Stream(Stream::from_raw(dict, raw)));
+            let saved = write_incremental(&doc, &SaveOptions::default()).unwrap();
+            assert_eq!(centre(saved), [255, 0, 0, 255], "{algorithm:?}: {what}");
+        }
+    }
+}

crates/render/src/raster/tests/png_predicted_images.rs

@@ -0,0 +1,69 @@
+//! #5430: Flate images with PNG predictors (ISO 32000-2 §7.4.4.4) are undone a byte row at a
+//! time (vendored hayro-syntax patch 35). The bit-level decoder they went through before dropped
+//! the last byte of each filtered row that ends part-way through a pixel, so every later row
+//! started a byte early and the picture came out sheared.
+
+use super::rgb_at;
+use crate::{PageRenderer, RenderConfig, RenderRequest, RequestKind};
+use flate2::{Compression, write::ZlibEncoder};
+use std::io::Write;
+use std::sync::Arc;
+
+/// The page is 150 × 200 pt, drawn at 72 dpi; the image fills it.
+const WIDTH: usize = 150;
+const HEIGHT: usize = 200;
+
+/// The colour of each of the image's four rows, top first, as 4-bit samples.
+const ROWS: [[u8; 3]; 4] = [[15, 0, 0], [0, 15, 0], [0, 0, 15], [15, 15, 0]];
+
+#[test]
+fn a_four_bit_rgb_image_of_odd_width_with_up_predicted_rows_is_not_sheared() {
+    // Three 4-bit RGB pixels are 4.5 bytes, so each row is five bytes and ends half-way through a
+    // two-byte pixel.
+    let rows: Vec<Vec<u8>> = ROWS
+        .iter()
+        .map(|rgb| {
+            let nibbles: Vec<u8> = (0..3).flat_map(|_| rgb.iter().copied()).chain([0]).collect();
+            nibbles.chunks(2).map(|pair| (pair[0] << 4) | pair[1]).collect()
+        })
+        .collect();
+    let mut predicted = Vec::new();
+    let mut above = vec![0u8; 5];
+    for row in &rows {
+        predicted.push(2);
+        predicted.extend(row.iter().zip(&above).map(|(b, a)| b.wrapping_sub(*a)));
+        above.clone_from(row);
+    }
+    let mut encoder = ZlibEncoder::new(Vec::new(), Compression::default());
+    encoder.write_all(&predicted).unwrap();
+    let data = encoder.finish().unwrap();
+
+    let content = "q 150 0 0 200 0 0 cm /Im0 Do Q";
+    let mut pdf = format!(
+        "%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n\
+         2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj\n\
+         3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 150 200] /Resources << /XObject << /Im0 5 0 R >> >> /Contents 4 0 R >> endobj\n\
+         4 0 obj << /Length {} >> stream\n{content}\nendstream endobj\n\
+         5 0 obj << /Type /XObject /Subtype /Image /Width 3 /Height 4 /ColorSpace /DeviceRGB /BitsPerComponent 4 \
+         /Filter /FlateDecode /DecodeParms << /Predictor 15 /Colors 3 /BitsPerComponent 4 /Columns 3 >> /Length {} >> stream\n",
+        content.len(),
+        data.len()
+    )
+    .into_bytes();
+    pdf.extend_from_slice(&data);
+    pdf.extend_from_slice(b"\nendstream endobj\ntrailer << /Root 1 0 R >>\n%%EOF");
+
+    let mut renderer = PageRenderer::new(Arc::new(pdf), RenderConfig::default());
+    let page = renderer.render(RenderRequest { page: 0, kind: RequestKind::Pixels, tile: None, scale: 1.0, tag: 0, preview: false });
+    assert!(page.error.is_none(), "{:?}", page.error);
+    assert_eq!((page.width, page.height), (WIDTH as u32, HEIGHT as u32));
+
+    // Each image pixel is 50 pt square; look at the middle of each.
+    for (row, rgb) in ROWS.iter().enumerate() {
+        let expected = rgb.map(|sample| sample * 17);
+        for column in 0..3 {
+            let (x, y) = (column * 50 + 25, row * 50 + 25);
+            assert_eq!(rgb_at(&page.rgba, WIDTH, x, y), expected, "image row {row}, column {column}");
+        }
+    }
+}

crates/ui-egui/src/app.rs

@@ -260,6 +260,7 @@ impl PdfCraftApp {
             fonts_cjk: theme::CjkPreference::Default,
             control: None,
             bookmark_rename: None,
+            bookmark_clipboard: None,
             last_opened_url: None,
             community_card_closed: false,
             pending_link: None,

crates/ui-egui/src/app/files.rs

@@ -1,4 +1,5 @@
 use super::*;
+use crate::file_filter::AddFilterAnyCase as _;
 
 /// Whether `a` and `b` name the same file: equal, or equal once made absolute against the
 /// current directory (links are not resolved, as in `last_session`).
@@ -705,7 +706,9 @@ impl PdfCraftApp {
     /// The File ▸ Open picker: PDFs, and images and text that become PDFs.
     #[cfg(not(target_arch = "wasm32"))]
     pub(super) fn open_picker() -> rfd::AsyncFileDialog {
-        rfd::AsyncFileDialog::new().add_filter("PDF", &["pdf"]).add_filter(tl!("Images and text (converted to PDF)"), &create_ui::CONVERTIBLE)
+        rfd::AsyncFileDialog::new()
+            .add_filter_any_case("PDF", &["pdf"])
+            .add_filter_any_case(tl!("Images and text (converted to PDF)"), &create_ui::CONVERTIBLE)
     }
 
     pub fn open_dialog(&mut self) {
@@ -713,7 +716,9 @@ impl PdfCraftApp {
         #[cfg(not(target_arch = "wasm32"))]
         self.pick(
             pickers::PickFor::Open,
-            rfd::AsyncFileDialog::new().add_filter("PDF", &["pdf"]).add_filter(tl!("Images and text (converted to PDF)"), &create_ui::CONVERTIBLE),
+            rfd::AsyncFileDialog::new()
+                .add_filter_any_case("PDF", &["pdf"])
+                .add_filter_any_case(tl!("Images and text (converted to PDF)"), &create_ui::CONVERTIBLE),
             true,
         );
         // Browsers pick files asynchronously; the bytes arrive through `inbox`.
@@ -723,8 +728,8 @@ impl PdfCraftApp {
             let ctx = self.ctx.clone();
             wasm_bindgen_futures::spawn_local(async move {
                 if let Some(h) = rfd::AsyncFileDialog::new()
-                    .add_filter("PDF", &["pdf"])
-                    .add_filter(tl!("Images and text"), &create_ui::CONVERTIBLE)
+                    .add_filter_any_case("PDF", &["pdf"])
+                    .add_filter_any_case(tl!("Images and text"), &create_ui::CONVERTIBLE)
                     .pick_file()
                     .await
                 {

crates/ui-egui/src/canvas.rs

@@ -12,7 +12,7 @@ use egui::{Align2, Color32, CornerRadius, Pos2, Rect, Sense, Stroke, TextureHand
 use pdfcraft_engine::{DocId, Edit};
 use pdfcraft_render::{DestView, DocInfo, LayerOp, LinkTarget, PRINT_TAG, PageText, RenderPool, RenderRequest, RequestKind, Tile, device_pixels};
 
-use crate::page_cursor::{Layer, Subject};
+use crate::page_cursor::Layer;
 use crate::page_pointer::PagePointer;
 use crate::theme::{self, Tokens};
 use crate::{PdfCraftApp, QuickTool, RightPanel, comments, icons, widgets};
@@ -28,6 +28,7 @@ pub(super) mod image_pick;
 mod navigation;
 mod organize;
 pub(super) mod page_cursor;
+mod page_input;
 pub(super) mod page_pointer;
 pub(super) mod page_router;
 pub mod scroll_speed;
@@ -62,6 +63,8 @@ pub(crate) use organize::grid_page_rect;
 use organize::organize_grid;
 #[cfg(test)]
 use organize::sharp_enough;
+pub(crate) use page_input::PageToolContext;
+use page_input::{PageInput, cancel_on_escape, page_overlays, page_tool_input, text_layer};
 use selection::{Selection, Span, click_unit, selection_actions};
 pub use xform::PageXform;
 use xform::snap_to_pixels;
@@ -883,6 +886,9 @@ impl DocView {
         self.sign.drag = None;
         self.redact_drag = None;
         self.crop_drag = None;
+        if let Some(q) = &mut self.camera {
+            q.grab = None;
+        }
         self.block_drag = None;
         self.org_drag = None;
         self.panel_drag = None;
@@ -1229,6 +1235,19 @@ struct PageFrame<'a> {
     current_height: f32,
     pressed_page: Option<usize>,
     calc_hover: Option<crate::calc_order_ui::Focus>,
+    /// A page took this frame's right-click.
+    right_clicked: bool,
+}
+
+impl PageFrame<'_> {
+    /// Where this frame's right-click is, on the page at `rect`, for the first page it is on: pages
+    /// that touch (the gaps hidden) can share a row of pixels, and a right-click there is one
+    /// page's, as a press is.
+    fn right_click_on(&mut self, rect: Rect) -> Option<Pos2> {
+        let p = self.pointer.filter(|p| !self.right_clicked && self.resp.secondary_clicked() && rect.contains(*p))?;
+        self.right_clicked = true;
+        Some(p)
+    }
 }
 
 /// Visible heights (points) closer than this are equal: one page size can meet the viewport a
@@ -1472,308 +1491,6 @@ fn paint_page_tiles(
     }
 }
 
-/// What the page's tools did with the pointer this frame.
-struct PageInput {
-    /// A tool, a field or a comment took the pointer: text selection must leave it alone.
-    consumed: bool,
-    /// Redact or Highlight draws boxes off text.
-    area_tool: bool,
-}
-
-/// Common geometry and pointer state for a tool acting on one page.
-#[derive(Clone, Copy)]
-pub(crate) struct PageToolContext<'a> {
-    pub ui: &'a egui::Ui,
-    pub resp: &'a egui::Response,
-    pub xf: &'a PageXform,
-    pub ptr: &'a PagePointer,
-    pub page: usize,
-    pub doc: &'a pdfcraft_engine::Document,
-    pub info: &'a DocInfo,
-}
-
-/// Comments: tools, selection, moving and resizing come before text selection. Form fields take
-/// clicks first with the Select tool (as Acrobat fills fields in every viewing mode); then
-/// comments; then text selection.
-fn page_tool_input(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot) -> PageInput {
-    let PageEnv {
-        added,
-        allowed,
-        author,
-        by_line,
-        can_crop,
-        can_fill,
-        can_modify,
-        comments_hidden,
-        custom_stamp,
-        date_text,
-        doc,
-        doc_links,
-        editing_content,
-        form,
-        info,
-        initials,
-        prefs,
-        preparing,
-        redact_mark,
-        signature,
-        table_preview,
-        text_style,
-        tool,
-        units,
-        fill_text_size,
-        fill_text_color,
-        ..
-    } = frame.env;
-    let PageSlot { i, xf, .. } = *slot;
-    let PageFrame { resp, ptr, pointer, .. } = *frame;
-    let cx = PageToolContext { ui, resp, xf: &xf, ptr, page: i, doc, info };
-    let pcx = comments::PageCx { page: i, xf: &xf, ptr, info, tool, prefs, allowed, hidden: comments_hidden, redact_mark };
-    let (lines, images) =
-        if matches!(tool, QuickTool::AddText | QuickTool::EditText) && can_modify { edit_inventory(view, doc, i) } else { Default::default() };
-    let field_tool = match tool {
-        QuickTool::Field(f) => Some(f),
-        _ => None,
-    };
-    // While a table is being set up, nothing else is drawn or moved.
-    let prepare_allowed = can_modify && table_preview.is_none() && frame.out.open_table.is_none();
-    let hits = PageHits {
-        page: i,
-        xf: &xf,
-        info,
-        tool,
-        pcx: &pcx,
-        form,
-        can_fill,
-        can_modify,
-        editing_content,
-        preparing,
-        field_tool,
-        prepare_allowed,
-        added,
-        lines: &lines,
-        images: &images,
-        clip: ui.clip_rect(),
-    };
-    if let Some(o) = ptr.pressed().filter(|o| xf.rect.contains(*o)) {
-        let at = hits.at(view, o);
-        view.router.press(i, at, tool);
-    }
-    if let QuickTool::Measure(measure_tool) = tool {
-        crate::measure_ui::page_input(ui, resp, doc, view, &pcx, measure_tool, units);
-    }
-
-    // Form fields take clicks first with the Select tool (as Acrobat fills fields in
-    // every viewing mode); then comments; then text selection.
-    if let QuickTool::Stamp(kind) = tool
-        && allowed
-        && let Some(p) = ptr.within(xf.rect)
-    {
-        view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
-        // The tool's own click: nothing drawn over the page here holds the press.
-        if resp.clicked() && view.router.owner(i).is_none() {
-            // Centred on the click, upright as the page is shown.
-            let (vx, vy) = xf.screen_to_view(p);
-            let (w, h) = kind.size();
-            let corners = [(vx as f64 - w / 2.0, vy as f64 - h / 2.0), (vx as f64 + w / 2.0, vy as f64 + h / 2.0)];
-            let u: Vec<[f32; 2]> = corners.iter().map(|(x, y)| info.pages[i].view_to_user(*x as f32, *y as f32)).collect();
-            let rect = [u[0][0].min(u[1][0]) as f64, u[0][1].min(u[1][1]) as f64, u[0][0].max(u[1][0]) as f64, u[0][1].max(u[1][1]) as f64];
-            let by = (kind.group() == pdfcraft_engine::StampGroup::Dynamic).then(|| by_line.clone());
-            let shape = pdfcraft_engine::Shape::Stamp { rect, stamp: kind, by };
-            view.pending_edit = Some(pdfcraft_engine::Edit::AddAnnotation(pdfcraft_engine::NewAnnotation {
-                page: i,
-                style: pdfcraft_engine::Style::default_for(&shape),
-                shape,
-                contents: String::new(),
-                author: author.clone(),
-            }));
-            frame.out.stamp_placed = true;
-        }
-    }
-    if let Some(cs) = custom_stamp.as_ref()
-        && allowed
-        && let Some(p) = ptr.within(xf.rect)
-    {
-        view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
-        // The tool's own click: nothing drawn over the page here holds the press.
-        if resp.clicked() && view.router.owner(i).is_none() {
-            // Centred on the click at its natural size (the engine sizes it).
-            let (vx, vy) = xf.screen_to_view(p);
-            let u = info.pages[i].view_to_user(vx, vy);
-            let (x, y) = (u[0] as f64, u[1] as f64);
-            view.pending_edit = Some(pdfcraft_engine::Edit::AddCustomStamp {
-                page: i,
-                rect: [x, y, x, y],
-                name: cs.name.clone(),
-                file: pdfcraft_engine::MarkFile { name: cs.file.clone(), bytes: cs.data.clone(), page: cs.page },
-                author: author.clone(),
-            });
-            frame.out.stamp_placed = true;
-        }
-    }
-    // Over a mark already placed, the Fill & Sign tool picks it up (comments, below).
-    if let QuickTool::Fill(ft) = tool
-        && allowed
-        && !comments::fill_grabs(&pcx, view)
-    {
-        match crate::fill_sign::page_input(
-            cx,
-            crate::fill_sign::PageInput {
-                tool: ft,
-                text_size: fill_text_size,
-                text_color: fill_text_color,
-                signature: signature.as_ref(),
-                initials: initials.as_ref(),
-                preview: frame.signature_preview,
-                author,
-                date_text,
-            },
-            view,
-        ) {
-            Some(crate::fill_sign::FillAction::Edit(e)) => view.pending_edit = Some(*e),
-            Some(crate::fill_sign::FillAction::Signature(e)) => {
-                view.pending_edit = Some(*e);
-                view.fill_signature_page = Some(i);
-            }
-            Some(crate::fill_sign::FillAction::CreateSignature) => frame.out.open_signature = true,
-            Some(crate::fill_sign::FillAction::CreateInitials) => frame.out.open_initials = true,
-            Some(crate::fill_sign::FillAction::Refused(why)) => frame.out.refused = Some(why),
-            None => {}
-        }
-    }
-    if matches!(tool, QuickTool::SignArea { .. }) {
-        crate::sign_ui::page_input(ui, resp, &xf, ptr, i, info, view);
-    }
-    if matches!(tool, QuickTool::MarqueeZoom | QuickTool::Snapshot) {
-        crate::zoom_snap::page_input(ui, resp, &xf, ptr, i, view);
-    }
-    if tool == QuickTool::EnhanceCamera {
-        crate::camera_ui::page_input(resp, &xf, ptr, i, view, can_modify);
-    }
-    if tool == QuickTool::Crop
-        && crate::crop::page_input(ui, crate::crop::CropPageInput { resp, xf: &xf, ptr, page: i, info, view, allowed: can_crop })
-    {
-        view.current = i;
-        frame.out.open_boxes = true;
-    }
-    let on_field = if preparing {
-        let o = crate::prepare::page_input(cx, form, field_tool, prepare_allowed, view);
-        frame.out.field_props |= o.properties;
-        frame.out.field_placed |= o.placed;
-        frame.out.open_table = frame.out.open_table.or(o.table);
-        o.consumed || field_tool.is_some()
-    } else {
-        tool == QuickTool::Select && crate::forms_ui::page_input(cx, form, can_fill, view)
-    };
-    // Redact draws boxes off text; so does Highlight (an area highlight, as in Acrobat).
-    let area_tool = tool == QuickTool::Redact && can_modify || tool == QuickTool::Comment(comments::CommentTool::Highlight) && allowed;
-    let boxing = area_tool && {
-        let text = view.page_text(i);
-        let over_text = |p: Pos2| {
-            let (vx, vy) = xf.screen_to_view(p);
-            text.as_ref().is_some_and(|t| t.glyphs.iter().any(|g| vx >= g.rect[0] && vx <= g.rect[2] && vy >= g.rect[1] && vy <= g.rect[3]))
-        };
-        crate::redact_ui::page_input(cx, over_text, view)
-    };
-    let on_objects = tool == QuickTool::EditText && can_modify && crate::object_ui::page_input(cx, view);
-    // Add text acts on the page's own paragraphs over them, and on the one its press was on until
-    // the button is up: a drag that leaves the box still ends, and no new box takes it over.
-    let over_source = tool == QuickTool::AddText
-        && (matches!(view.router.owner(i), Some(crate::page_router::Owner::Paragraph { .. }))
-            || pointer.is_some_and(|p| {
-                !crate::content_ui::hits_added(&xf, info, i, added, p) && crate::edit_text_ui::over_paragraph(&xf, info, i, &lines, p)
-            }));
-    let source_blocked = over_source && view.content.hold_blocked();
-    if over_source && resp.clicked() && !source_blocked {
-        if let Some(edit) = view.content.finish_draft(added) {
-            view.pending_edit = Some(edit);
-        }
-        view.content.selected = None;
-    }
-    let on_content = !on_objects && editing_content && can_modify && {
-        source_blocked
-            || crate::content_ui::page_input(
-                cx,
-                added,
-                tool == QuickTool::AddText && !over_source,
-                matches!(tool, QuickTool::AddText | QuickTool::EditText),
-                text_style,
-                view,
-            )
-            || tool == QuickTool::AddText && !over_source
-    };
-    // Added content owns its gesture; its source text must not queue a second edit.
-    // Edit text & images boxes every paragraph and image whenever the tool is on. Only the
-    // input waits while selected objects or added content own the pointer, or while page
-    // input is blocked (another tab, a dialog, the window unfocused): the boxes stay drawn
-    // instead of vanishing until the pointer comes back.
-    let others_own_pointer = on_objects || on_content;
-    let on_edit_text = (tool == QuickTool::EditText || over_source) && can_modify && {
-        // Editable text takes precedence over background/overlapping artwork. Both
-        // inventories are painted every frame, even when text owns the pointer.
-        let text_used = crate::edit_text_ui::page_input(cx, &lines, view, !others_own_pointer);
-        let image_cx = crate::edit_text_ui::ImageCx {
-            ui,
-            resp,
-            xf: &xf,
-            ptr,
-            page: i,
-            info,
-            allow_interaction: !others_own_pointer && (matches!(view.router.owner(i), Some(crate::page_router::Owner::Picture { .. })) || !text_used),
-        };
-        let image_used = crate::edit_text_ui::image_input(&image_cx, &images, view);
-        !others_own_pointer && (text_used || image_used)
-    };
-    if tool == QuickTool::EditText {
-        if others_own_pointer {
-            if ptr.pressed().is_some() || resp.clicked() || resp.secondary_clicked() {
-                view.image_selection = None;
-            }
-        } else {
-            crate::content_ui::sync_image_selection(view, i, &images, added);
-        }
-    }
-    let on_link = tool == QuickTool::Link && can_modify && crate::link_ui::page_input(cx, doc_links, view);
-    if tool == QuickTool::Select
-        && resp.secondary_clicked()
-        && can_modify
-        && let Some(p) = pointer.filter(|p| xf.rect.contains(*p))
-        && let Some(l) = doc.links().iter().find(|l| l.page == i && crate::link_ui::screen_rect(&xf, info, i, l.rect).expand(2.0).contains(p))
-    {
-        view.links.context = Some((i, l.index));
-    }
-    let consumed = on_objects || on_edit_text || on_link || on_content || boxing || on_field || comments::page_input(ui, resp, &pcx, view);
-    // The cursor and the tip from what lies under the pointer, after the tools claimed theirs (the
-    // last claim on a layer stands).
-    if frame.env.unobstructed
-        && let Some(p) = pointer
-    {
-        for h in hits.at(view, p) {
-            view.cursor.claim_with_tip(h.layer, h.icon, h.tip);
-        }
-    }
-    PageInput { consumed, area_tool }
-}
-
-/// Edit text's paragraphs and pictures on page `i`, kept while the document is unchanged.
-fn edit_inventory(
-    view: &mut DocView,
-    doc: &pdfcraft_engine::Document,
-    i: usize,
-) -> (Vec<pdfcraft_engine::TextBlock>, Vec<pdfcraft_engine::PageImage>) {
-    let generation = doc.edit_generation();
-    let lines = match view.edit_lines.get(&i) {
-        Some((g, l)) if *g == generation => l.clone(),
-        _ => {
-            let l = doc.text_blocks(i);
-            view.edit_lines.insert(i, (generation, l.clone()));
-            l
-        }
-    };
-    let images = cached_edit_images(view, doc, i).to_vec();
-    (lines, images)
-}
-
 /// Images parsed once per page and document edit generation, shared by painting and menus.
 fn cached_edit_images<'a>(view: &'a mut DocView, doc: &pdfcraft_engine::Document, page: usize) -> &'a [pdfcraft_engine::PageImage] {
     let generation = doc.edit_generation();
@@ -1784,478 +1501,6 @@ fn cached_edit_images<'a>(view: &'a mut DocView, doc: &pdfcraft_engine::Document
     &entry.1
 }
 
-/// What the page modules have under a point on one page, for the page router.
-struct PageHits<'a> {
-    page: usize,
-    xf: &'a PageXform,
-    info: &'a DocInfo,
-    tool: QuickTool,
-    pcx: &'a comments::PageCx<'a>,
-    form: &'a [pdfcraft_engine::FormField],
-    can_fill: bool,
-    can_modify: bool,
-    /// Edit a PDF is open: added text and pictures can be picked up.
-    editing_content: bool,
-    preparing: bool,
-    field_tool: Option<crate::prepare::FieldTool>,
-    /// Prepare may draw and move fields (not while a table is being set up).
-    prepare_allowed: bool,
-    added: &'a [pdfcraft_engine::Added],
-    lines: &'a [pdfcraft_engine::TextBlock],
-    images: &'a [pdfcraft_engine::PageImage],
-    /// The pages' visible area (the picture's rotate knob stays inside it).
-    clip: Rect,
-}
-
-impl PageHits<'_> {
-    /// The hits at `p`, bottom up: links, comments; Edit text's pictures under its paragraphs (text
-    /// on top of artwork takes the press), added content, the objects selected together and the
-    /// open paragraph's frame, the selected picture's grips over them all; then form fields
-    /// (Prepare's, being moved, over the comments; filled ones under added content and the
-    /// comments that move).
-    fn at(&self, view: &DocView, p: Pos2) -> Vec<crate::page_router::Hit> {
-        let PageHits {
-            page,
-            xf,
-            info,
-            tool,
-            pcx,
-            form,
-            can_fill,
-            can_modify,
-            editing_content,
-            preparing,
-            field_tool,
-            prepare_allowed,
-            added,
-            lines,
-            images,
-            clip,
-        } = *self;
-        // Crop mode owns presses on its page, including the controls beside its
-        // frame. Underlying paragraphs and the empty-page marquee must not take
-        // a crop button's press before the image module receives it.
-        if tool == QuickTool::EditText
-            && can_modify
-            && let Some(selection) = view.image_selection.as_ref().filter(|s| s.page == page && s.crop.is_some())
-        {
-            return vec![crate::page_router::Hit::new(
-                crate::page_router::Owner::Picture { index: selection.index, part: crate::page_router::PicturePart::Body },
-                crate::page_cursor::Layer::Handle,
-                egui::CursorIcon::Default,
-            )];
-        }
-        let fields = if preparing {
-            crate::prepare::hit(xf, info, page, form, field_tool, prepare_allowed, &view.prepare, p)
-        } else if tool == QuickTool::Select {
-            crate::forms_ui::hit(xf, info, page, form, can_fill, p)
-        } else {
-            None
-        };
-        // With Add text, only the paragraphs and pictures not under added content.
-        let editing =
-            can_modify && (tool == QuickTool::EditText || tool == QuickTool::AddText && !crate::content_ui::hits_added(xf, info, page, added, p));
-        let (pictures, paragraphs, objects, grips) = if editing {
-            let open = view.line_editor.as_ref().filter(|e| e.page == page);
-            let frame = open
-                .filter(|e| !e.has_changes())
-                .and_then(|e| lines.get(e.block))
-                .map(|l| xf.user_rect(info, page, l.rect.map(|v| v as f32)).expand(2.0));
-            // Add text acts on the page's paragraphs only in their boxes, edges included (it
-            // finishes the box being typed there, `over_source`): not on pictures, nor beside a
-            // paragraph, where a click starts a new box.
-            let edit_text = tool == QuickTool::EditText;
-            let on_paragraphs = edit_text || crate::edit_text_ui::over_paragraph(xf, info, page, lines, p);
-            (
-                edit_text.then(|| crate::edit_text_ui::picture_hit(xf, page, info, images, view, p)).flatten(),
-                on_paragraphs.then(|| crate::edit_text_ui::hit(xf, info, page, lines, open.map(|e| e.block), p)).flatten(),
-                edit_text.then(|| crate::object_ui::hit(view, xf, info, page, frame, p)).flatten(),
-                edit_text.then(|| crate::edit_text_ui::picture_handle_hit(clip, xf, page, info, images, view, p)).flatten(),
-            )
-        } else {
-            (None, None, None, None)
-        };
-        // Added text and pictures, over the page's own paragraphs and under the objects selected
-        // together.
-        let picks_up = matches!(tool, QuickTool::Select | QuickTool::AddText | QuickTool::EditText);
-        let added = (editing_content && can_modify && picks_up).then(|| crate::content_ui::hit(xf, info, page, added, view, p)).flatten();
-        [link_hit(info, xf, page, p), comments::hit(pcx, view, p), pictures, paragraphs, added, objects, grips, fields]
-            .into_iter()
-            .flatten()
-            .collect()
-    }
-}
-
-/// Text layer: find matches, selection, I-beam and drag-to-select.
-fn text_layer(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot, input: &PageInput) {
-    let PageEnv { info, selects_text, tool, .. } = frame.env;
-    let PageSlot { i, r, xf } = *slot;
-    let PageFrame { resp, ptr, pointer, .. } = *frame;
-    if let Some(text) = view.texts.get(&i).cloned() {
-        paint_text_marks(ui, view, &text, i, xf, resp.dragged());
-        if selects_text
-            && !input.consumed
-            && let Some(p) = pointer.filter(|p| r.contains(*p))
-        {
-            text_pointer_input(ui, view, &text, TextPointer { page: i, xf, rect: r, info, tool, resp, ptr: ptr.clone(), pointer: p });
-        }
-    }
-}
-
-fn paint_text_marks(ui: &egui::Ui, view: &DocView, text: &PageText, page: usize, xf: PageXform, dragging: bool) {
-    let painter = ui.painter();
-    let to_screen = |g: [f32; 4]| xf.view_rect(g);
-    if let Some(find) = &view.find {
-        for (index, (match_page, range)) in find.matches.iter().enumerate() {
-            if *match_page != page {
-                continue;
-            }
-            let fill = if find.current == Some(index) {
-                Color32::from_rgba_unmultiplied(255, 140, 0, 110)
-            } else {
-                Color32::from_rgba_unmultiplied(255, 214, 0, 90)
-            };
-            for line_rect in text.line_rects(range.clone()) {
-                painter.rect_filled(to_screen(line_rect).expand(1.0), CornerRadius::same(2), fill);
-            }
-        }
-    }
-    if view.all_text {
-        for line_rect in text.line_rects(0..text.glyphs.len()) {
-            painter.rect_filled(to_screen(line_rect), CornerRadius::same(1), Color32::from_rgba_unmultiplied(0x3A, 0x7B, 0xF0, 70));
-        }
-    }
-    if let Some(selection) = view.selection.filter(|selection| selection.page == page) {
-        for line_rect in selection.rects(text) {
-            painter.rect_filled(to_screen(line_rect), CornerRadius::same(1), Color32::from_rgba_unmultiplied(0x3A, 0x7B, 0xF0, 70));
-        }
-        if let Span::Column { rect } = selection.span
-            && dragging
-        {
-            let outline = Stroke::new(1.0, Color32::from_rgb(0x3A, 0x7B, 0xF0));
-            painter.rect_stroke(to_screen(rect), CornerRadius::ZERO, outline, egui::StrokeKind::Middle);
-        }
-    }
-}
-
-struct TextPointer<'a> {
-    page: usize,
-    xf: PageXform,
-    rect: Rect,
-    info: &'a DocInfo,
-    tool: QuickTool,
-    resp: &'a egui::Response,
-    ptr: PagePointer,
-    pointer: Pos2,
-}
-
-struct TextGesture<'a> {
-    page: usize,
-    xf: PageXform,
-    rect: Rect,
-    tool: QuickTool,
-    ptr: PagePointer,
-    resp: &'a egui::Response,
-    pointer: Pos2,
-    vx: f32,
-    vy: f32,
-    over_text: bool,
-    over_link: bool,
-    column: bool,
-}
-
-fn text_pointer_input(ui: &mut egui::Ui, view: &mut DocView, text: &PageText, pointer: TextPointer<'_>) {
-    let TextPointer { page, xf, rect, info, tool, resp, ptr, pointer: screen_pointer } = pointer;
-    let (vx, vy) = xf.screen_to_view(screen_pointer);
-    let over_text = text.glyphs.iter().any(|glyph| vx >= glyph.rect[0] && vx <= glyph.rect[2] && vy >= glyph.rect[1] && vy <= glyph.rect[3]);
-    let over_link = info.links.iter().any(|link| link.page == page && xf.user_rect(info, page, link.rect).contains(screen_pointer));
-    let column = tool == QuickTool::ColumnSelect || ui.input(|input| input.modifiers.alt);
-    let gesture = TextGesture { page, xf, rect, tool, ptr, resp, pointer: screen_pointer, vx, vy, over_text, over_link, column };
-    update_text_cursor(view, &gesture);
-    update_selection_on_press(ui, view, text, &gesture);
-    update_dragged_selection(view, text, &gesture);
-    finish_text_pointer_gesture(ui, view, text, &gesture);
-}
-
-fn update_text_cursor(view: &mut DocView, gesture: &TextGesture<'_>) {
-    // A press on a link selects nothing (it is the link's), so no cursor here says it would.
-    if gesture.column && !gesture.over_link {
-        view.cursor.claim(Layer::Text, egui::CursorIcon::Crosshair);
-    } else if gesture.over_text && !gesture.over_link {
-        view.cursor.claim(Layer::Text, egui::CursorIcon::Text);
-    }
-}
-
-fn update_selection_on_press(ui: &egui::Ui, view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
-    // A press held by what keeps its drag (a link, a comment that moves) selects no text; one on
-    // text markup lets its drag select the text underneath.
-    let press_here = gesture.ptr.origin.is_some_and(|origin| gesture.rect.contains(origin));
-    if gesture.ptr.pressed().is_some() && press_here && !view.router.keeps_drag() {
-        let now = ui.input(|input| input.time);
-        let (max_delay, max_dist) = ui.ctx().options(|options| (options.input_options.max_double_click_delay, options.input_options.max_click_dist));
-        let consecutive = now - view.last_press_time <= max_delay && view.last_press_pos.is_some_and(|pos| pos.distance(gesture.pointer) <= max_dist);
-        view.clicks = if consecutive { view.clicks.saturating_add(1) } else { 1 };
-        view.last_press_time = now;
-        view.last_press_pos = Some(gesture.pointer);
-        let clicks = selection_click_count(view.clicks, gesture.tool);
-        if clicks >= 2
-            && gesture.over_text
-            && let Some((first, last)) = text.nearest(gesture.vx, gesture.vy).and_then(|anchor| click_unit(text, clicks, anchor))
-        {
-            view.selection = Some(Selection::run(gesture.page, first, last));
-        }
-    }
-    if gesture.resp.drag_started() && press_here && !view.router.keeps_drag() {
-        view.actions_dismissed = None;
-        view.selection_drag = true;
-        let origin = gesture.ptr.origin.unwrap_or(gesture.pointer);
-        let (ox, oy) = gesture.xf.screen_to_view(origin);
-        if view.clicks < 2 {
-            view.selection = if gesture.column {
-                Some(Selection { page: gesture.page, span: Span::Column { rect: [ox, oy, gesture.vx, gesture.vy] } })
-            } else {
-                text.nearest(ox, oy).map(|anchor| Selection::run(gesture.page, anchor, anchor))
-            };
-        }
-    }
-}
-
-fn selection_click_count(clicks: u32, tool: QuickTool) -> u32 {
-    if clicks > 2 && tool != QuickTool::Select { 1 } else { clicks }
-}
-
-fn update_dragged_selection(view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
-    let clicks = selection_click_count(view.clicks, gesture.tool);
-    if gesture.resp.dragged()
-        && let Some(selection) = view.selection.as_mut().filter(|selection| selection.page == gesture.page)
-    {
-        match &mut selection.span {
-            Span::Run { anchor, head } if clicks >= 2 => {
-                if let Some(hit) = text.nearest(gesture.vx, gesture.vy)
-                    && let Some((first, last)) = click_unit(text, clicks, *anchor)
-                {
-                    let (to_first, to_last) = click_unit(text, clicks, hit).unwrap_or((hit, hit));
-                    (*anchor, *head) = if to_first < first { (last, to_first) } else { (first, to_last.max(last)) };
-                }
-            }
-            Span::Run { head, .. } => {
-                if let Some(hit) = text.nearest(gesture.vx, gesture.vy) {
-                    *head = hit;
-                }
-            }
-            Span::Column { rect } => {
-                rect[2] = gesture.vx;
-                rect[3] = gesture.vy;
-            }
-        }
-    }
-    if gesture.resp.drag_stopped()
-        && view.selection.is_some_and(|selection| {
-            selection.page == gesture.page && matches!(selection.span, Span::Column { .. }) && selection.text(text).is_empty()
-        })
-    {
-        view.selection = None;
-    }
-}
-
-fn finish_text_pointer_gesture(ui: &egui::Ui, view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
-    let release_clicks = if gesture.resp.triple_clicked() {
-        view.clicks.max(2).saturating_add(1)
-    } else if gesture.resp.double_clicked() {
-        view.clicks.max(2)
-    } else {
-        0
-    };
-    if release_clicks > 0 {
-        view.clicks = release_clicks;
-    }
-    let clicks = selection_click_count(view.clicks, gesture.tool);
-    if release_clicks > 0
-        && clicks >= 2
-        && gesture.over_text
-        && view.selection.is_none()
-        && let Some((first, last)) = text.nearest(gesture.vx, gesture.vy).and_then(|anchor| click_unit(text, clicks, anchor))
-    {
-        view.selection = Some(Selection::run(gesture.page, first, last));
-    } else if gesture.resp.clicked() && view.clicks < 2 && !view.router.keeps_drag() {
-        let shift = ui.input(|input| input.modifiers.shift);
-        match (
-            view.selection.as_mut().filter(|selection| shift && selection.page == gesture.page).map(|selection| &mut selection.span),
-            text.nearest(gesture.vx, gesture.vy),
-        ) {
-            (Some(Span::Run { head, .. }), Some(hit)) => *head = hit,
-            _ => view.selection = None,
-        }
-    }
-}
-
-/// Everything drawn over the page after its text: pictures, comments, content, links, fields, marks
-/// and badges.
-fn page_overlays(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot, input: &PageInput) {
-    let PageEnv {
-        added,
-        allowed,
-        calc_order,
-        can_modify,
-        comments_hidden,
-        doc,
-        doc_links,
-        editing_content,
-        form,
-        generation,
-        info,
-        prefs,
-        preparing,
-        redact_mark,
-        table_preview,
-        tool,
-        unobstructed,
-        ..
-    } = frame.env;
-    let PageSlot { i, xf, .. } = *slot;
-    let PageFrame { resp, ptr, pointer, .. } = *frame;
-    let painter = ui.painter();
-    let tool_cx = PageToolContext { ui, resp, xf: &xf, ptr, page: i, doc, info };
-    let pcx = comments::PageCx { page: i, xf: &xf, ptr, info, tool, prefs, allowed, hidden: comments_hidden, redact_mark };
-    if tool == QuickTool::Select && !input.consumed {
-        crate::image_pick::page_input(resp, &xf, i, info, doc, pointer, view);
-    }
-    crate::image_pick::drop_stale(doc, view);
-    crate::image_pick::paint(painter, &xf, i, info, view);
-    // A cancelled press ends no selection: no markup or redaction is made from it.
-    if !view.press_cancelled {
-        comments::page_after_text(resp, &pcx, view);
-        if tool == QuickTool::Redact && can_modify {
-            crate::redact_ui::after_text(resp, i, info, view);
-        }
-    }
-    if input.area_tool {
-        crate::redact_ui::paint(painter, i, view, pointer);
-    }
-    comments::paint_page(ui, painter, &pcx, view);
-    if editing_content {
-        crate::content_ui::paint_page(painter, &xf, i, info, added, view, pointer);
-    }
-    if tool == QuickTool::EditText {
-        crate::object_ui::paint(painter, &xf, i, info, &view.objects);
-    }
-    if tool == QuickTool::EnhanceCamera {
-        crate::camera_ui::paint(painter, &xf, i, view);
-    }
-    if tool == QuickTool::Link {
-        crate::link_ui::paint(painter, &xf, i, info, doc_links, view, pointer);
-    }
-    if preparing {
-        crate::prepare::paint_page(tool_cx, form, view);
-        if let Some(preview) = &table_preview {
-            crate::field_table_ui::paint_preview(painter, &xf, i, preview);
-        }
-        if calc_order {
-            let selected = view.prepare.selected.as_ref().map(|(name, _)| name.as_str());
-            if let Some(field) = crate::calc_order_ui::paint_page(tool_cx, form, &view.calc_order, generation, selected) {
-                frame.calc_hover = Some(field);
-            }
-        }
-    } else {
-        crate::forms_ui::paint_page(painter, &xf, i, info, form, view, pointer);
-    }
-
-    // Form-field highlight (Acrobat's "Highlight existing fields"); required fields get a
-    // red border. Radio buttons and round XFA check boxes are round, and so is theirs (as
-    // in Acrobat). Only what can be filled is marked: a read-only widget (its field's, or a
-    // radio button's own) is left as it is drawn.
-    paint_field_highlights(painter, &xf, info, form.as_slice(), i, view.highlight_fields);
-    // Links: the hand and the link's target, which count only for the tools that follow or
-    // edit links (`Layer::reached_by`). Tips draw above the palette, so none shows while it is
-    // open, even beside it. A click follows the link its press was on, released over it: one that
-    // slips off the link first follows nothing, as a button's does.
-    if unobstructed
-        && resp.clicked()
-        && tool == QuickTool::Select
-        && !input.consumed
-        && let Some(owner @ crate::page_router::Owner::Link { index }) = view.router.owner(i)
-        && pointer.and_then(|p| link_hit(info, &xf, i, p)).is_some_and(|h| h.owner == owner)
-        && let Some(l) = info.links.get(index)
-    {
-        frame.out.clicked_link = Some(l.target.clone());
-    }
-    // Comments say what they are with any tool, beside its cursor, as Acrobat's do.
-    comments::describe(&pcx, view);
-    for (mp, mr, mc) in &view.compare_marks {
-        if *mp == i {
-            let sr = xf.user_rect(info, i, *mr).expand(1.5);
-            painter.rect_filled(sr, CornerRadius::same(2), mc.gamma_multiply(0.28));
-        }
-    }
-    if let Some((fp, fr, t0)) = view.flash
-        && fp == i
-    {
-        let now = ui.input(|inp| inp.time);
-        let t0 = if t0 == 0.0 { now } else { t0 };
-        view.flash = Some((fp, fr, t0));
-        let age = (now - t0) as f32;
-        if age < 1.6 {
-            let a = ((1.6 - age) / 1.6 * 255.0) as u8;
-            let sr = xf.user_rect(info, i, fr).expand(4.0);
-            painter.rect_stroke(
-                sr,
-                CornerRadius::same(3),
-                Stroke::new(2.5, Color32::from_rgba_unmultiplied(0x1B, 0x63, 0xE0, a)),
-                egui::StrokeKind::Outside,
-            );
-            ui.ctx().request_repaint();
-        } else {
-            view.flash = None;
-        }
-    }
-    // Validation is viewer chrome over the signer's original artwork, which
-    // may still say "Signature Not Verified". These badges never enter document
-    // streams, image/text exports, vector printing or Print as Image.
-    for badge in signature_badges(&doc.signatures, i) {
-        let [x0, y0, x1, y1] = badge.rect;
-        let sr = xf.user_rect(info, i, [x0 as f32, y0 as f32, x1 as f32, y1 as f32]);
-        let (icon, color) = crate::sign_ui::signature_status_style(badge.status);
-        painter.rect_stroke(sr, CornerRadius::same(2), Stroke::new(1.5, color), egui::StrokeKind::Outside);
-        // A widget too small for the mark keeps its outline: the verdict still shows.
-        if sr.width() < 4.0 || sr.height() < 4.0 {
-            continue;
-        }
-        // Big enough to read at a glance, small enough to leave the signer's own
-        // text visible around it.
-        let side = (sr.width().min(sr.height()) * 0.8).clamp(24.0, 192.0);
-        let mark = Rect::from_center_size(sr.center(), vec2(side, side));
-        icons::paint(ui, mark, icon, side * 0.64, color);
-        // Overlapping widgets paint in order, so the topmost badge's verdict is the tip, with
-        // any tool; a link's or a comment's tip wins over any badge.
-        if pointer.is_some_and(|p| mark.expand(2.0).contains(p)) {
-            view.cursor.describe(Subject::SignatureBadge, badge.summary.to_string());
-        }
-    }
-}
-
-fn paint_field_highlights(painter: &egui::Painter, xf: &PageXform, info: &DocInfo, form: &[pdfcraft_engine::FormField], page: usize, enabled: bool) {
-    if !enabled {
-        return;
-    }
-    for field in form.iter() {
-        let required = field.has(pdfcraft_engine::field_flags::REQUIRED);
-        for widget in field.widgets.iter().filter(|widget| widget.page == Some(page) && !widget.hidden && !widget.read_only) {
-            let rect = widget.rect;
-            let screen_rect = xf.user_rect(info, page, [rect[0] as f32, rect[1] as f32, rect[2] as f32, rect[3] as f32]);
-            let tint = Color32::from_rgba_unmultiplied(0x6E, 0x8E, 0xF5, 48);
-            let (width, color) = if required { (2.0, Color32::from_rgb(0xE3, 0x22, 0x22)) } else { (1.0, Color32::from_rgb(0x6E, 0x8E, 0xF5)) };
-            if widget.round {
-                let radius = screen_rect.width().min(screen_rect.height()) / 2.0;
-                painter.circle_filled(screen_rect.center(), radius, tint);
-                painter.circle_stroke(screen_rect.center(), radius - width / 2.0, Stroke::new(width, color));
-            } else {
-                painter.rect_filled(screen_rect, CornerRadius::same(1), tint);
-                painter.rect_stroke(screen_rect, CornerRadius::same(1), Stroke::new(width, color), egui::StrokeKind::Inside);
-            }
-        }
-    }
-}
-
 fn draw_page(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, i: usize) {
     let PageEnv { allowed, comments_hidden, doc, editing_content, info, ppp, prefs, rects, redact_mark, scale, t, tool, .. } = frame.env;
     let PageFrame { ptr, origin, visible, pressed, pointer, .. } = *frame;
@@ -2294,10 +1539,18 @@ fn draw_page(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, i
     }
 
     let slot = PageSlot { i, r, xf };
-    // A cancelled press takes nothing until the button is up.
-    let input = if view.press_cancelled { PageInput { consumed: true, area_tool: false } } else { page_tool_input(ui, view, frame, &slot) };
-    let painter = ui.painter();
     let pcx = comments::PageCx { page: i, xf: &xf, ptr, info, tool, prefs, allowed, hidden: comments_hidden, redact_mark };
+    // A cancelled press takes nothing until the button is up, though the page's menu still opens
+    // where a right-click is.
+    let input = if view.press_cancelled {
+        if let Some(p) = frame.right_click_on(xf.rect) {
+            comments::anchor(&pcx, p, view);
+        }
+        PageInput { consumed: true, area_tool: false, hover: None, released_over: false }
+    } else {
+        page_tool_input(ui, view, frame, &slot)
+    };
+    let painter = ui.painter();
     let preview_target = (matches!(tool, QuickTool::Select | QuickTool::Fill(_)) && !comments_hidden).then_some(view.comments.selected).flatten();
     view.signature_drag.prepare(ui.ctx(), doc, preview_target, scale);
     view.signature_drag.paint(painter, &pcx, &view.comments, view.pending_edit.as_ref());
@@ -2317,43 +1570,6 @@ fn draw_page(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, i
     page_overlays(ui, view, frame, &slot, &input);
 }
 
-/// The link under `p` on `page`: the hand, and where a click goes. Only the Select tool follows
-/// links and the Link tool edits them (`Layer::reached_by`).
-fn link_hit(info: &DocInfo, xf: &PageXform, page: usize, p: Pos2) -> Option<crate::page_router::Hit> {
-    let (index, l) = info.links.iter().enumerate().rfind(|(_, l)| l.page == page && xf.user_rect(info, page, l.rect).contains(p))?;
-    let label = match &l.target {
-        LinkTarget::Page(n, _) => crate::i18n::fmt(tl!("Go to page {p}"), &[("p", info.pages.get(*n).map(|p| p.label.as_str()).unwrap_or("?"))]),
-        LinkTarget::Uri(u) => u.clone(),
-        LinkTarget::SetLayers { .. } => tl!("Set layer visibility").to_string(),
-        LinkTarget::RemoteGoTo { file, .. } => file.clone(),
-        LinkTarget::Other(s) => crate::i18n::fmt(tl!("{s} action"), &[("s", s)]),
-    };
-    let owner = crate::page_router::Owner::Link { index };
-    Some(crate::page_router::Hit { tip: Some(label), ..crate::page_router::Hit::new(owner, Layer::Link, egui::CursorIcon::PointingHand) })
-}
-
-/// Escape while the pages hold a press abandons the gesture it drives, whichever tool's: nothing is
-/// placed, drawn, moved, resized or opened, and the press is ignored until the button is up. The
-/// frame of the release still belongs to the cancelled press.
-fn cancel_on_escape(ctx: &egui::Context, view: &mut DocView, ptr: &PagePointer) {
-    // Over once the button is up and its release seen, or when a new press comes (its release and
-    // the next press can share a frame).
-    let new_press = matches!(ptr.edges.last(), Some(crate::page_pointer::Edge::Press(_)));
-    if view.press_cancelled && (new_press || !ptr.any_down && ptr.edges.is_empty()) {
-        view.press_cancelled = false;
-    }
-    if !view.press_cancelled && ptr.origin.is_some() && ptr.primary_down && ctx.input_mut(|i| i.consume_key(egui::Modifiers::NONE, egui::Key::Escape))
-    {
-        // A text selection being dragged goes with its drag: the markup, redaction or Replace
-        // Text that its end would make is not made.
-        if view.selection_drag {
-            view.clear_selection();
-        }
-        view.cancel_pointer_gestures();
-        view.press_cancelled = true;
-    }
-}
-
 #[allow(clippy::cognitive_complexity)]
 fn draw_pages(
     ui: &mut egui::Ui,
@@ -2439,9 +1655,9 @@ fn draw_pages(
     cancel_on_escape(ui.ctx(), view, &ptr);
     view.router.settle(ptr.any_down, !ptr.edges.is_empty());
     // A new press is no longer the last one's, wherever it lands (the page it is on gives it
-    // its owner; in the gap between pages it has none).
+    // its owner; in the gap between pages it is no page's).
     if ptr.pressed().is_some() {
-        view.router.cancel();
+        view.router.begin();
         // The page widget is not focusable. Explicitly return keyboard ownership from Pages
         // when the user presses the document, without stealing focus through a modal.
         if let Some(id) = view.pages_focus_id {
@@ -2456,6 +1672,11 @@ fn draw_pages(
     if resp.secondary_clicked() {
         // Set again below when the right-click lands on a link.
         view.links.context = None;
+        // Set again below by the page right-clicked: a right-click off the pages (between them,
+        // beside one) anchors no page's menu, which then acts on the current page. It deselects the
+        // comment too (below), as one on a page's empty part does. A selected Prepare field keeps
+        // its menu, off the pages as on them.
+        view.comments.context_at = None;
         let mut over_image = false;
         if tool == QuickTool::EditText {
             let pointer_pos = ptr.pos;
@@ -2520,13 +1741,28 @@ fn draw_pages(
         current_height: f32::INFINITY,
         pressed_page: None,
         calc_hover: None,
+        right_clicked: false,
     };
     for &i in visible_pages {
         draw_page(ui, view, &mut frame, i);
     }
     let PageFrame {
-        wanted, visible_now, mut current, best_overlap, current_overlap, current_height, pressed_page, calc_hover, out: page_out, ..
+        wanted,
+        visible_now,
+        mut current,
+        best_overlap,
+        current_overlap,
+        current_height,
+        pressed_page,
+        calc_hover,
+        out: page_out,
+        right_clicked,
+        ..
     } = frame;
+    // A right-click no page took deselects the comment, so the page's menu opens, not the comment's.
+    if resp.secondary_clicked() && !right_clicked {
+        view.comments.selected = None;
+    }
     let PageOut {
         mut canvas_action,
         clicked_link,
@@ -2695,7 +1931,9 @@ fn draw_pages(
                 }));
         if is_image_menu && let Some(sel) = view.image_selection.clone() {
             let images = cached_edit_images(view, doc, sel.page).to_vec();
-            let at = view.comments.context_at.map(|(_, at)| at);
+            // Paste lands where the menu opened only on the picture's page: where pages touch, the
+            // first page takes the right-click, and its point means nothing on the second.
+            let at = view.comments.context_at.filter(|(page, _)| *page == sel.page).map(|(_, at)| at);
             let rotation = (view.rotation % 360 + info.pages.get(sel.page).map_or(0, |p| p.rotation % 360)) % 360;
             crate::edit_text_ui::image_context_menu(ui, view, &images, sel.page, sel.index, can_paste_image, &mut image_action, at, rotation);
             return;

crates/ui-egui/src/canvas/crop.rs

@@ -27,10 +27,12 @@ pub(crate) struct CropPageInput<'a> {
     pub(crate) info: &'a DocInfo,
     pub(crate) view: &'a mut DocView,
     pub(crate) allowed: bool,
+    /// Nobody holds the press, and it began on this page: the tool's.
+    pub(crate) free: bool,
 }
 
 pub(crate) fn page_input(ui: &egui::Ui, input: CropPageInput<'_>) -> bool {
-    let CropPageInput { resp, xf, ptr, page, info, view, allowed } = input;
+    let CropPageInput { resp, xf, ptr, page, info, view, allowed, free } = input;
     let (pointer, origin) = (ptr.pos, ptr.origin);
     if pointer.is_some_and(|p| xf.rect.contains(p)) {
         view.cursor.claim(Layer::ToolArea, if allowed { egui::CursorIcon::Crosshair } else { egui::CursorIcon::NotAllowed });
@@ -38,9 +40,9 @@ pub(crate) fn page_input(ui: &egui::Ui, input: CropPageInput<'_>) -> bool {
     if !allowed {
         return false;
     }
-    // The tool's own press, of the primary button: nothing drawn over the page here holds it.
+    // The tool's own press, of the primary button: one nobody holds.
     if resp.drag_started_by(egui::PointerButton::Primary)
-        && view.router.owner(page).is_none()
+        && free
         && let Some(o) = origin.filter(|o| xf.rect.contains(*o))
     {
         view.crop_drag = Some((page, o));

crates/ui-egui/src/canvas/page_input.rs

@@ -0,0 +1,900 @@
+//! Page input: what the tools do with the pointer on one page, what lies under it for the page
+//! router, the text layer, and what is drawn over the page after its text.
+
+use egui::{Color32, CornerRadius, Pos2, Rect, Stroke, vec2};
+use pdfcraft_render::{DocInfo, PageText};
+
+use super::{DocView, PageEnv, PageFrame, PageSlot, PageXform, Selection, Span, cached_edit_images, click_unit, signature_badges};
+use crate::page_cursor::{Layer, Subject};
+use crate::page_pointer::PagePointer;
+use crate::page_router::{Owner, PagePress, top};
+use crate::{QuickTool, comments, icons};
+
+/// What the page's tools did with the pointer this frame.
+pub(super) struct PageInput {
+    /// A tool, a field or a comment took the pointer: text selection must leave it alone.
+    pub(super) consumed: bool,
+    /// Redact or Highlight draws boxes off text.
+    pub(super) area_tool: bool,
+    /// What a press under the pointer would take (the top hit there), for hover painting.
+    pub(super) hover: Option<crate::page_router::Hit>,
+    /// The press's click came up over what the press began on: a link's or a field's click counts
+    /// only then, as a button's does.
+    pub(super) released_over: bool,
+}
+
+/// Common geometry and pointer state for a tool acting on one page.
+#[derive(Clone, Copy)]
+pub(crate) struct PageToolContext<'a> {
+    pub ui: &'a egui::Ui,
+    pub resp: &'a egui::Response,
+    pub xf: &'a PageXform,
+    pub ptr: &'a PagePointer,
+    pub page: usize,
+    pub doc: &'a pdfcraft_engine::Document,
+    pub info: &'a DocInfo,
+}
+
+/// The tools' input on one page. The hits at the press point decide who holds the press, and the
+/// modules are told what the press is to this page (`PagePress`): their own, nobody's (the active
+/// tool's: `tool_input`, and the tools still called here), or another page's. The Edit text group
+/// still asks the router, until it is told too. Text selection runs after, on what nobody took.
+pub(super) fn page_tool_input(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot) -> PageInput {
+    let PageEnv {
+        added,
+        allowed,
+        can_fill,
+        can_modify,
+        comments_hidden,
+        doc,
+        doc_links,
+        editing_content,
+        form,
+        info,
+        prefs,
+        preparing,
+        redact_mark,
+        table_preview,
+        text_style,
+        tool,
+        ..
+    } = frame.env;
+    let PageSlot { i, xf, .. } = *slot;
+    let PageFrame { resp, ptr, pointer, .. } = *frame;
+    let cx = PageToolContext { ui, resp, xf: &xf, ptr, page: i, doc, info };
+    let pcx = comments::PageCx { page: i, xf: &xf, ptr, info, tool, prefs, allowed, hidden: comments_hidden, redact_mark };
+    let (lines, images) =
+        if matches!(tool, QuickTool::AddText | QuickTool::EditText) && can_modify { edit_inventory(view, doc, i) } else { Default::default() };
+    let field_tool = match tool {
+        QuickTool::Field(f) => Some(f),
+        _ => None,
+    };
+    // While a table is being set up, nothing else is drawn or moved.
+    let prepare_allowed = can_modify && table_preview.is_none() && frame.out.open_table.is_none();
+    let hits = PageHits {
+        page: i,
+        xf: &xf,
+        info,
+        tool,
+        pcx: &pcx,
+        form,
+        can_fill,
+        can_modify,
+        editing_content,
+        preparing,
+        field_tool,
+        prepare_allowed,
+        added,
+        doc_links,
+        lines: &lines,
+        images: &images,
+        clip: ui.clip_rect(),
+    };
+    if let Some(o) = ptr.pressed().filter(|o| xf.rect.contains(*o)) {
+        let at = hits.at(view, o);
+        view.router.press(i, at, tool);
+    }
+    // What this page has to do with the press: its owner's, the active tool's, or another page's.
+    let press = view.router.press_for(i);
+    // What lies under the pointer before the tools act, on the frames that need it: for a click's
+    // release, a right-click's tool checks, and Fill & Sign's preview.
+    let wants_under = resp.clicked() || resp.secondary_clicked() || matches!(tool, QuickTool::Fill(_)) && !ptr.any_down;
+    let under = pointer.filter(|p| wants_under && xf.rect.contains(*p)).map(|p| hits.at(view, p)).unwrap_or_default();
+    let released_over = match press {
+        PagePress::Mine(owner) if resp.clicked() => under.iter().any(|h| h.owner == owner),
+        _ => false,
+    };
+    // A right-click while the primary button is held (a comment moved, a box drawn) leaves the
+    // selections that press acts on alone. egui ends the press's own interaction when any button is
+    // released, the right-click's own frame included, so the button is what tells. A touch's long
+    // press, which egui reports as a right-click with the finger still down, opens its menu.
+    let press_held = ptr.primary_down && !resp.long_touched();
+    let context = frame.right_click_on(xf.rect).and_then(|p| right_click(&hits, &under, view, p, press_held));
+    // A mark already placed takes its own press (comments, below), as does one being moved on this
+    // page until its move ends; with no button down the Fill & Sign tool's preview hides where a
+    // press would be taken (a mark, its handles, a Prepare field).
+    let over_mark = matches!(tool, QuickTool::Fill(_))
+        && (matches!(press, PagePress::Mine(_)) || comments::moving_on(view, i) || !ptr.any_down && top(under.iter().cloned(), tool).is_some());
+    tool_input(ui, view, frame, slot, &pcx, press, over_mark);
+    let on_field = if preparing {
+        let o = crate::prepare::page_input(cx, form, field_tool, prepare_allowed, press, view);
+        frame.out.field_props |= o.properties;
+        frame.out.field_placed |= o.placed;
+        frame.out.open_table = frame.out.open_table.or(o.table);
+        o.consumed || field_tool.is_some()
+    } else {
+        tool == QuickTool::Select && crate::forms_ui::page_input(cx, form, can_fill, press, released_over, view)
+    };
+    // Redact draws boxes off text; so does Highlight (an area highlight, as in Acrobat).
+    let area_tool = tool == QuickTool::Redact && can_modify || tool == QuickTool::Comment(comments::CommentTool::Highlight) && allowed;
+    let boxing = area_tool && {
+        let text = view.page_text(i);
+        let over_text = |p: Pos2| {
+            let (vx, vy) = xf.screen_to_view(p);
+            text.as_ref().is_some_and(|t| t.glyphs.iter().any(|g| vx >= g.rect[0] && vx <= g.rect[2] && vy >= g.rect[1] && vy <= g.rect[3]))
+        };
+        crate::redact_ui::page_input(cx, over_text, press == PagePress::Free, view)
+    };
+    let on_objects = tool == QuickTool::EditText && can_modify && crate::object_ui::page_input(cx, view);
+    // Add text acts on the page's own paragraphs over them, and on the one its press was on until
+    // the button is up: a drag that leaves the box still ends, and no new box takes it over.
+    let over_source = tool == QuickTool::AddText
+        && (matches!(view.router.owner(i), Some(crate::page_router::Owner::Paragraph { .. }))
+            || pointer.is_some_and(|p| {
+                !crate::content_ui::hits_added(&xf, info, i, added, p) && crate::edit_text_ui::over_paragraph(&xf, info, i, &lines, p)
+            }));
+    let source_blocked = over_source && view.content.hold_blocked();
+    if over_source && resp.clicked() && !source_blocked {
+        if let Some(edit) = view.content.finish_draft(added) {
+            view.pending_edit = Some(edit);
+        }
+        view.content.selected = None;
+    }
+    let on_content = !on_objects && editing_content && can_modify && {
+        source_blocked
+            || crate::content_ui::page_input(
+                cx,
+                added,
+                tool == QuickTool::AddText && !over_source,
+                matches!(tool, QuickTool::AddText | QuickTool::EditText),
+                text_style,
+                view,
+            )
+            || tool == QuickTool::AddText && !over_source
+    };
+    // Added content owns its gesture; its source text must not queue a second edit.
+    // Edit text & images boxes every paragraph and image whenever the tool is on. Only the
+    // input waits while selected objects or added content own the pointer, or while page
+    // input is blocked (another tab, a dialog, the window unfocused): the boxes stay drawn
+    // instead of vanishing until the pointer comes back.
+    let others_own_pointer = on_objects || on_content;
+    let on_edit_text = (tool == QuickTool::EditText || over_source) && can_modify && {
+        // Editable text takes precedence over background/overlapping artwork. Both
+        // inventories are painted every frame, even when text owns the pointer.
+        let text_used = crate::edit_text_ui::page_input(cx, &lines, view, !others_own_pointer);
+        let image_cx = crate::edit_text_ui::ImageCx {
+            ui,
+            resp,
+            xf: &xf,
+            ptr,
+            page: i,
+            info,
+            allow_interaction: !others_own_pointer && (matches!(view.router.owner(i), Some(crate::page_router::Owner::Picture { .. })) || !text_used),
+        };
+        let image_used = crate::edit_text_ui::image_input(&image_cx, &images, view);
+        !others_own_pointer && (text_used || image_used)
+    };
+    if tool == QuickTool::EditText {
+        if others_own_pointer {
+            if ptr.pressed().is_some() || resp.clicked() || resp.secondary_clicked() {
+                view.image_selection = None;
+            }
+        } else {
+            crate::content_ui::sync_image_selection(view, i, &images, added);
+        }
+    }
+    let (link_owner, link_context) = (link_of(press.owner()), link_of(context));
+    let on_link = tool == QuickTool::Link && can_modify && crate::link_ui::page_input(cx, press == PagePress::Free, link_owner, link_context, view);
+    if tool == QuickTool::Select
+        && can_modify
+        && let Some(index) = link_context
+    {
+        view.links.context = Some((i, index));
+    }
+    // Comments, every frame: their own presses, a commenting tool's, and a click elsewhere that
+    // leaves them unselected. A press nobody holds that another tool took this frame (Prepare's
+    // selection rectangle, added content, which still decide for themselves) is not also a
+    // commenting tool's, as before.
+    let taken = on_objects || on_edit_text || on_link || on_content || boxing || on_field;
+    let on_comment = comments::page_input(ui, resp, &pcx, press, taken, view);
+    let consumed = taken || on_comment;
+    let hover = pointer.and_then(|p| claim_under(&hits, view, p, frame.env.unobstructed));
+    PageInput { consumed, area_tool, hover, released_over }
+}
+
+/// What lies under the pointer at `p`, after the tools act: its top, what a press there would take,
+/// for hover painting. With `claim` (nothing drawn over the pages, such as the palette), its cursor
+/// and tip too, after the tools claimed theirs (the last claim on a layer stands).
+fn claim_under(hits: &PageHits<'_>, view: &mut DocView, p: Pos2, claim: bool) -> Option<crate::page_router::Hit> {
+    let under = hits.at(view, p);
+    if claim {
+        for h in &under {
+            view.cursor.claim_with_tip(h.layer, h.icon, h.tip.clone());
+        }
+    }
+    top(under, hits.tool)
+}
+
+/// The link `owner` is, by its `/Annots` index.
+fn link_of(owner: Option<Owner>) -> Option<usize> {
+    match owner {
+        Some(Owner::Link { index }) => Some(index),
+        _ => None,
+    }
+}
+
+/// The active tool's own input on page `i`: the one gate for presses nobody holds. Measure, the
+/// stamps, Fill & Sign, Sign area, zoom and snapshot, the camera's quadrilateral and crop act only
+/// on a press that began on this page and that no hit won (`press` is Free), and keep their cursor
+/// and gestures. The camera also drags a corner whose press it holds, and crop's double-click
+/// opens Set Page Boxes wherever it is. `over_mark`: with Fill & Sign, a hit holds the press (a
+/// mark's, or a Prepare field's), a mark is being moved on this page, or with no button down a press
+/// under the pointer would be taken (a mark, its handles, a Prepare field).
+fn tool_input(
+    ui: &egui::Ui,
+    view: &mut DocView,
+    frame: &mut PageFrame<'_>,
+    slot: &PageSlot,
+    pcx: &comments::PageCx<'_>,
+    press: PagePress,
+    over_mark: bool,
+) {
+    let PageEnv {
+        allowed,
+        author,
+        by_line,
+        can_crop,
+        can_modify,
+        custom_stamp,
+        date_text,
+        doc,
+        info,
+        initials,
+        signature,
+        tool,
+        units,
+        fill_text_size,
+        fill_text_color,
+        ..
+    } = frame.env;
+    let PageSlot { i, xf, .. } = *slot;
+    let PageFrame { resp, ptr, .. } = *frame;
+    let cx = PageToolContext { ui, resp, xf: &xf, ptr, page: i, doc, info };
+    let free = press == PagePress::Free;
+    if let QuickTool::Measure(measure_tool) = tool {
+        crate::measure_ui::page_input(ui, crate::measure_ui::Clicks::of(resp, free), doc, view, pcx, measure_tool, units);
+    }
+    if let QuickTool::Stamp(kind) = tool
+        && allowed
+        && crate::stamps_ui::place(cx, kind, by_line, author, free, view)
+    {
+        frame.out.stamp_placed = true;
+    }
+    if let Some(cs) = custom_stamp.as_ref()
+        && allowed
+        && crate::stamps_ui::place_custom(cx, cs, author, free, view)
+    {
+        frame.out.stamp_placed = true;
+    }
+    if let QuickTool::Fill(ft) = tool
+        && allowed
+        && !over_mark
+    {
+        let input = crate::fill_sign::PageInput {
+            tool: ft,
+            text_size: fill_text_size,
+            text_color: fill_text_color,
+            signature: signature.as_ref(),
+            initials: initials.as_ref(),
+            preview: frame.signature_preview,
+            author,
+            date_text,
+        };
+        match crate::fill_sign::page_input(cx, input, free, view) {
+            Some(crate::fill_sign::FillAction::Edit(e)) => view.pending_edit = Some(*e),
+            Some(crate::fill_sign::FillAction::Signature(e)) => {
+                view.pending_edit = Some(*e);
+                view.fill_signature_page = Some(i);
+            }
+            Some(crate::fill_sign::FillAction::CreateSignature) => frame.out.open_signature = true,
+            Some(crate::fill_sign::FillAction::CreateInitials) => frame.out.open_initials = true,
+            Some(crate::fill_sign::FillAction::Refused(why)) => frame.out.refused = Some(why),
+            None => {}
+        }
+    }
+    if matches!(tool, QuickTool::SignArea { .. }) {
+        crate::sign_ui::page_input(cx, free, view);
+    }
+    if matches!(tool, QuickTool::MarqueeZoom | QuickTool::Snapshot) {
+        crate::zoom_snap::page_input(ui, resp, &xf, ptr, i, free, view);
+    }
+    if tool == QuickTool::EnhanceCamera {
+        crate::camera_ui::page_input(resp, &xf, ptr, i, view, can_modify, press);
+    }
+    if tool == QuickTool::Crop
+        && crate::crop::page_input(ui, crate::crop::CropPageInput { resp, xf: &xf, ptr, page: i, info, view, allowed: can_crop, free })
+    {
+        view.current = i;
+        frame.out.open_boxes = true;
+    }
+}
+
+/// A right-click at `p`: the page's menu opens there, and it goes to what lies on top there
+/// ([`PageHits::context_at`]), which the menu then acts on. A comment there is selected, and none
+/// elsewhere; a Prepare field is selected; links take theirs from what this returns.
+/// `under`: the hits at `p` before the tools act. `press_held`: the primary button is held, and the
+/// comment and Prepare selections its press acts on are left alone until its release; links still
+/// take theirs, as before.
+fn right_click(hits: &PageHits<'_>, under: &[crate::page_router::Hit], view: &mut DocView, p: Pos2, press_held: bool) -> Option<Owner> {
+    let context = hits.context_at(view, p, under);
+    // Delete page, Paste and Copy Image act where the menu opened, whoever takes the right-click.
+    comments::anchor(hits.pcx, p, view);
+    if press_held {
+        return context;
+    }
+    // Add text takes every right-click on a page it can change, Edit text those on its own
+    // paragraphs and pictures (the objects selected together, and crop mode's picture, among them),
+    // the Link tool those on a link, and a Prepare field tool the whole page, as before: comments
+    // see none of them.
+    let tool_takes_it = match hits.tool {
+        QuickTool::AddText => hits.can_modify,
+        QuickTool::EditText => under.iter().any(|h| matches!(h.owner, Owner::Paragraph { .. } | Owner::Picture { .. } | Owner::Objects { .. })),
+        QuickTool::Link => hits.can_modify && matches!(context, Some(Owner::Link { .. })),
+        _ => hits.field_tool.is_some(),
+    };
+    if !tool_takes_it {
+        let comment = match context {
+            Some(Owner::Comment { index, .. }) => Some(index),
+            _ => None,
+        };
+        comments::context(hits.pcx, comment, view);
+    }
+    if let Some(Owner::PrepareField { field, widget }) = context {
+        crate::prepare::context(hits.form, field, widget, view);
+    }
+    context
+}
+
+/// Edit text's paragraphs and pictures on page `i`, kept while the document is unchanged.
+fn edit_inventory(
+    view: &mut DocView,
+    doc: &pdfcraft_engine::Document,
+    i: usize,
+) -> (Vec<pdfcraft_engine::TextBlock>, Vec<pdfcraft_engine::PageImage>) {
+    let generation = doc.edit_generation();
+    let lines = match view.edit_lines.get(&i) {
+        Some((g, l)) if *g == generation => l.clone(),
+        _ => {
+            let l = doc.text_blocks(i);
+            view.edit_lines.insert(i, (generation, l.clone()));
+            l
+        }
+    };
+    let images = cached_edit_images(view, doc, i).to_vec();
+    (lines, images)
+}
+
+/// What the page modules have under a point on one page, for the page router.
+struct PageHits<'a> {
+    page: usize,
+    xf: &'a PageXform,
+    info: &'a DocInfo,
+    tool: QuickTool,
+    pcx: &'a comments::PageCx<'a>,
+    form: &'a [pdfcraft_engine::FormField],
+    can_fill: bool,
+    can_modify: bool,
+    /// Edit a PDF is open: added text and pictures can be picked up.
+    editing_content: bool,
+    preparing: bool,
+    field_tool: Option<crate::prepare::FieldTool>,
+    /// Prepare may draw and move fields (not while a table is being set up).
+    prepare_allowed: bool,
+    added: &'a [pdfcraft_engine::Added],
+    /// The document's links, as the engine lists them (the Link tool edits every one).
+    doc_links: &'a [pdfcraft_engine::LinkItem],
+    lines: &'a [pdfcraft_engine::TextBlock],
+    images: &'a [pdfcraft_engine::PageImage],
+    /// The pages' visible area (the picture's rotate knob stays inside it).
+    clip: Rect,
+}
+
+impl PageHits<'_> {
+    /// The hits at `p`, bottom up ([`Self::hits`]).
+    fn at(&self, view: &DocView, p: Pos2) -> Vec<crate::page_router::Hit> {
+        self.hits(view, p, false)
+    }
+
+    /// What a right-click at `p` is on: what lies on top there, as for a press, but with every
+    /// tool reaching comments and links, as a comment's menu shows whatever the tool. A highlight
+    /// over a link is the highlight's ([`comments::context_hit`]).
+    /// The Link tool edits links and reaches no comment: on a document it can change, its
+    /// right-click is what its press there would take (`under`, the hits at `p`), when that is
+    /// anything.
+    fn context_at(&self, view: &DocView, p: Pos2, under: &[crate::page_router::Hit]) -> Option<Owner> {
+        if self.tool == QuickTool::Link
+            && self.can_modify
+            && let Some(press) = top(under.iter().cloned(), QuickTool::Link)
+        {
+            return Some(press.owner);
+        }
+        top(self.hits(view, p, true), QuickTool::Select).map(|h| h.owner)
+    }
+
+    /// The hits at `p`, bottom up: links, comments; Edit text's pictures under its paragraphs (text
+    /// on top of artwork takes the press), added content, the objects selected together and the
+    /// open paragraph's frame, the selected picture's grips over them all; the camera tool's corners;
+    /// then form fields (Prepare's, being moved, over the comments; filled ones under added content
+    /// and the comments that move). In crop mode, only the picture being cropped.
+    /// For a right-click (`context`), comments by [`comments::context_hit`], and no camera corner (it
+    /// has no menu).
+    fn hits(&self, view: &DocView, p: Pos2, context: bool) -> Vec<crate::page_router::Hit> {
+        let PageHits {
+            page,
+            xf,
+            info,
+            tool,
+            pcx,
+            form,
+            can_fill,
+            can_modify,
+            editing_content,
+            preparing,
+            field_tool,
+            prepare_allowed,
+            added,
+            doc_links,
+            lines,
+            images,
+            clip,
+        } = *self;
+        // Crop mode owns every press on its page (`edit_text_ui::crop_hit`).
+        if tool == QuickTool::EditText
+            && can_modify
+            && let Some(crop) = crate::edit_text_ui::crop_hit(view, page)
+        {
+            return vec![crop];
+        }
+        let fields = if preparing {
+            crate::prepare::hit(xf, info, page, form, field_tool, prepare_allowed, &view.prepare, p)
+        } else if tool == QuickTool::Select {
+            crate::forms_ui::hit(xf, info, page, form, can_fill, p)
+        } else {
+            None
+        };
+        // With Add text, only the paragraphs and pictures not under added content.
+        let editing =
+            can_modify && (tool == QuickTool::EditText || tool == QuickTool::AddText && !crate::content_ui::hits_added(xf, info, page, added, p));
+        let (pictures, paragraphs, objects, grips) = if editing {
+            let open = view.line_editor.as_ref().filter(|e| e.page == page);
+            let frame = open
+                .filter(|e| !e.has_changes())
+                .and_then(|e| lines.get(e.block))
+                .map(|l| xf.user_rect(info, page, l.rect.map(|v| v as f32)).expand(2.0));
+            // Add text acts on the page's paragraphs only in their boxes, edges included (it
+            // finishes the box being typed there, `over_source`): not on pictures, nor beside a
+            // paragraph, where a click starts a new box.
+            let edit_text = tool == QuickTool::EditText;
+            let on_paragraphs = edit_text || crate::edit_text_ui::over_paragraph(xf, info, page, lines, p);
+            (
+                edit_text.then(|| crate::edit_text_ui::picture_hit(xf, page, info, images, view, p)).flatten(),
+                on_paragraphs.then(|| crate::edit_text_ui::hit(xf, info, page, lines, open.map(|e| e.block), p)).flatten(),
+                edit_text.then(|| crate::object_ui::hit(view, xf, info, page, frame, p)).flatten(),
+                edit_text.then(|| crate::edit_text_ui::picture_handle_hit(clip, xf, page, info, images, view, p)).flatten(),
+            )
+        } else {
+            (None, None, None, None)
+        };
+        // Added text and pictures, over the page's own paragraphs and under the objects selected
+        // together.
+        let picks_up = matches!(tool, QuickTool::Select | QuickTool::AddText | QuickTool::EditText);
+        let added = (editing_content && can_modify && picks_up).then(|| crate::content_ui::hit(xf, info, page, added, view, p)).flatten();
+        let corner = (!context && tool == QuickTool::EnhanceCamera && can_modify).then(|| crate::camera_ui::hit(xf, page, view, p)).flatten();
+        let link = crate::link_ui::hit(xf, info, page, doc_links, tool, p);
+        let comment = if context { comments::context_hit(pcx, p) } else { comments::hit(pcx, view, p, link.is_some()) };
+        [link, comment, pictures, paragraphs, added, objects, grips, corner, fields].into_iter().flatten().collect()
+    }
+}
+
+/// Text layer: find matches, selection, I-beam and drag-to-select.
+pub(super) fn text_layer(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot, input: &PageInput) {
+    let PageEnv { info, selects_text, tool, .. } = frame.env;
+    let PageSlot { i, r, xf } = *slot;
+    let PageFrame { resp, ptr, pointer, .. } = *frame;
+    if let Some(text) = view.texts.get(&i).cloned() {
+        paint_text_marks(ui, view, &text, i, xf, resp.dragged());
+        if selects_text
+            && !input.consumed
+            && let Some(p) = pointer.filter(|p| r.contains(*p))
+        {
+            text_pointer_input(ui, view, &text, TextPointer { page: i, xf, rect: r, info, tool, resp, ptr: ptr.clone(), pointer: p });
+        }
+    }
+}
+
+fn paint_text_marks(ui: &egui::Ui, view: &DocView, text: &PageText, page: usize, xf: PageXform, dragging: bool) {
+    let painter = ui.painter();
+    let to_screen = |g: [f32; 4]| xf.view_rect(g);
+    if let Some(find) = &view.find {
+        for (index, (match_page, range)) in find.matches.iter().enumerate() {
+            if *match_page != page {
+                continue;
+            }
+            let fill = if find.current == Some(index) {
+                Color32::from_rgba_unmultiplied(255, 140, 0, 110)
+            } else {
+                Color32::from_rgba_unmultiplied(255, 214, 0, 90)
+            };
+            for line_rect in text.line_rects(range.clone()) {
+                painter.rect_filled(to_screen(line_rect).expand(1.0), CornerRadius::same(2), fill);
+            }
+        }
+    }
+    if view.all_text {
+        for line_rect in text.line_rects(0..text.glyphs.len()) {
+            painter.rect_filled(to_screen(line_rect), CornerRadius::same(1), Color32::from_rgba_unmultiplied(0x3A, 0x7B, 0xF0, 70));
+        }
+    }
+    if let Some(selection) = view.selection.filter(|selection| selection.page == page) {
+        for line_rect in selection.rects(text) {
+            painter.rect_filled(to_screen(line_rect), CornerRadius::same(1), Color32::from_rgba_unmultiplied(0x3A, 0x7B, 0xF0, 70));
+        }
+        if let Span::Column { rect } = selection.span
+            && dragging
+        {
+            let outline = Stroke::new(1.0, Color32::from_rgb(0x3A, 0x7B, 0xF0));
+            painter.rect_stroke(to_screen(rect), CornerRadius::ZERO, outline, egui::StrokeKind::Middle);
+        }
+    }
+}
+
+struct TextPointer<'a> {
+    page: usize,
+    xf: PageXform,
+    rect: Rect,
+    info: &'a DocInfo,
+    tool: QuickTool,
+    resp: &'a egui::Response,
+    ptr: PagePointer,
+    pointer: Pos2,
+}
+
+struct TextGesture<'a> {
+    page: usize,
+    xf: PageXform,
+    rect: Rect,
+    tool: QuickTool,
+    ptr: PagePointer,
+    resp: &'a egui::Response,
+    pointer: Pos2,
+    vx: f32,
+    vy: f32,
+    over_text: bool,
+    over_link: bool,
+    column: bool,
+}
+
+fn text_pointer_input(ui: &mut egui::Ui, view: &mut DocView, text: &PageText, pointer: TextPointer<'_>) {
+    let TextPointer { page, xf, rect, info, tool, resp, ptr, pointer: screen_pointer } = pointer;
+    let (vx, vy) = xf.screen_to_view(screen_pointer);
+    let over_text = text.glyphs.iter().any(|glyph| vx >= glyph.rect[0] && vx <= glyph.rect[2] && vy >= glyph.rect[1] && vy <= glyph.rect[3]);
+    let over_link = info.links.iter().any(|link| link.page == page && xf.user_rect(info, page, link.rect).contains(screen_pointer));
+    let column = tool == QuickTool::ColumnSelect || ui.input(|input| input.modifiers.alt);
+    let gesture = TextGesture { page, xf, rect, tool, ptr, resp, pointer: screen_pointer, vx, vy, over_text, over_link, column };
+    update_text_cursor(view, &gesture);
+    update_selection_on_press(ui, view, text, &gesture);
+    update_dragged_selection(view, text, &gesture);
+    finish_text_pointer_gesture(ui, view, text, &gesture);
+}
+
+fn update_text_cursor(view: &mut DocView, gesture: &TextGesture<'_>) {
+    // A press on a link selects nothing (it is the link's), so no cursor here says it would.
+    if gesture.column && !gesture.over_link {
+        view.cursor.claim(Layer::Text, egui::CursorIcon::Crosshair);
+    } else if gesture.over_text && !gesture.over_link {
+        view.cursor.claim(Layer::Text, egui::CursorIcon::Text);
+    }
+}
+
+fn update_selection_on_press(ui: &egui::Ui, view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
+    // A press held by what keeps its drag (a link, a comment that moves) selects no text; one on
+    // text markup lets its drag select the text underneath.
+    let press_here = gesture.ptr.origin.is_some_and(|origin| gesture.rect.contains(origin));
+    if gesture.ptr.pressed().is_some() && press_here && !view.router.keeps_drag() {
+        let now = ui.input(|input| input.time);
+        let (max_delay, max_dist) = ui.ctx().options(|options| (options.input_options.max_double_click_delay, options.input_options.max_click_dist));
+        let consecutive = now - view.last_press_time <= max_delay && view.last_press_pos.is_some_and(|pos| pos.distance(gesture.pointer) <= max_dist);
+        view.clicks = if consecutive { view.clicks.saturating_add(1) } else { 1 };
+        view.last_press_time = now;
+        view.last_press_pos = Some(gesture.pointer);
+        let clicks = selection_click_count(view.clicks, gesture.tool);
+        if clicks >= 2
+            && gesture.over_text
+            && let Some((first, last)) = text.nearest(gesture.vx, gesture.vy).and_then(|anchor| click_unit(text, clicks, anchor))
+        {
+            view.selection = Some(Selection::run(gesture.page, first, last));
+        }
+    }
+    if gesture.resp.drag_started() && press_here && !view.router.keeps_drag() {
+        view.actions_dismissed = None;
+        view.selection_drag = true;
+        let origin = gesture.ptr.origin.unwrap_or(gesture.pointer);
+        let (ox, oy) = gesture.xf.screen_to_view(origin);
+        if view.clicks < 2 {
+            view.selection = if gesture.column {
+                Some(Selection { page: gesture.page, span: Span::Column { rect: [ox, oy, gesture.vx, gesture.vy] } })
+            } else {
+                text.nearest(ox, oy).map(|anchor| Selection::run(gesture.page, anchor, anchor))
+            };
+        }
+    }
+}
+
+fn selection_click_count(clicks: u32, tool: QuickTool) -> u32 {
+    if clicks > 2 && tool != QuickTool::Select { 1 } else { clicks }
+}
+
+fn update_dragged_selection(view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
+    let clicks = selection_click_count(view.clicks, gesture.tool);
+    if gesture.resp.dragged()
+        && let Some(selection) = view.selection.as_mut().filter(|selection| selection.page == gesture.page)
+    {
+        match &mut selection.span {
+            Span::Run { anchor, head } if clicks >= 2 => {
+                if let Some(hit) = text.nearest(gesture.vx, gesture.vy)
+                    && let Some((first, last)) = click_unit(text, clicks, *anchor)
+                {
+                    let (to_first, to_last) = click_unit(text, clicks, hit).unwrap_or((hit, hit));
+                    (*anchor, *head) = if to_first < first { (last, to_first) } else { (first, to_last.max(last)) };
+                }
+            }
+            Span::Run { head, .. } => {
+                if let Some(hit) = text.nearest(gesture.vx, gesture.vy) {
+                    *head = hit;
+                }
+            }
+            Span::Column { rect } => {
+                rect[2] = gesture.vx;
+                rect[3] = gesture.vy;
+            }
+        }
+    }
+    if gesture.resp.drag_stopped()
+        && view.selection.is_some_and(|selection| {
+            selection.page == gesture.page && matches!(selection.span, Span::Column { .. }) && selection.text(text).is_empty()
+        })
+    {
+        view.selection = None;
+    }
+}
+
+fn finish_text_pointer_gesture(ui: &egui::Ui, view: &mut DocView, text: &PageText, gesture: &TextGesture<'_>) {
+    let release_clicks = if gesture.resp.triple_clicked() {
+        view.clicks.max(2).saturating_add(1)
+    } else if gesture.resp.double_clicked() {
+        view.clicks.max(2)
+    } else {
+        0
+    };
+    if release_clicks > 0 {
+        view.clicks = release_clicks;
+    }
+    let clicks = selection_click_count(view.clicks, gesture.tool);
+    if release_clicks > 0
+        && clicks >= 2
+        && gesture.over_text
+        && view.selection.is_none()
+        && let Some((first, last)) = text.nearest(gesture.vx, gesture.vy).and_then(|anchor| click_unit(text, clicks, anchor))
+    {
+        view.selection = Some(Selection::run(gesture.page, first, last));
+    } else if gesture.resp.clicked() && view.clicks < 2 && !view.router.keeps_drag() {
+        let shift = ui.input(|input| input.modifiers.shift);
+        match (
+            view.selection.as_mut().filter(|selection| shift && selection.page == gesture.page).map(|selection| &mut selection.span),
+            text.nearest(gesture.vx, gesture.vy),
+        ) {
+            (Some(Span::Run { head, .. }), Some(hit)) => *head = hit,
+            _ => view.selection = None,
+        }
+    }
+}
+
+/// Everything drawn over the page after its text: pictures, comments, content, links, fields, marks
+/// and badges.
+pub(super) fn page_overlays(ui: &mut egui::Ui, view: &mut DocView, frame: &mut PageFrame<'_>, slot: &PageSlot, input: &PageInput) {
+    let PageEnv {
+        added,
+        allowed,
+        calc_order,
+        can_modify,
+        comments_hidden,
+        doc,
+        doc_links,
+        editing_content,
+        form,
+        generation,
+        info,
+        prefs,
+        preparing,
+        redact_mark,
+        table_preview,
+        tool,
+        unobstructed,
+        ..
+    } = frame.env;
+    let PageSlot { i, xf, .. } = *slot;
+    let PageFrame { resp, ptr, pointer, .. } = *frame;
+    let painter = ui.painter();
+    let tool_cx = PageToolContext { ui, resp, xf: &xf, ptr, page: i, doc, info };
+    let pcx = comments::PageCx { page: i, xf: &xf, ptr, info, tool, prefs, allowed, hidden: comments_hidden, redact_mark };
+    if tool == QuickTool::Select && !input.consumed {
+        crate::image_pick::page_input(resp, &xf, i, info, doc, pointer, view);
+    }
+    crate::image_pick::drop_stale(doc, view);
+    crate::image_pick::paint(painter, &xf, i, info, view);
+    // A cancelled press ends no selection: no markup or redaction is made from it.
+    if !view.press_cancelled {
+        comments::page_after_text(resp, &pcx, view);
+        if tool == QuickTool::Redact && can_modify {
+            crate::redact_ui::after_text(resp, i, info, view);
+        }
+    }
+    if input.area_tool {
+        crate::redact_ui::paint(painter, i, view, pointer);
+    }
+    comments::paint_page(ui, painter, &pcx, view, input.hover.as_ref());
+    if editing_content {
+        crate::content_ui::paint_page(painter, &xf, i, info, added, view, pointer);
+    }
+    if tool == QuickTool::EditText {
+        crate::object_ui::paint(painter, &xf, i, info, &view.objects);
+    }
+    if tool == QuickTool::EnhanceCamera {
+        crate::camera_ui::paint(painter, &xf, i, view);
+    }
+    if tool == QuickTool::Link {
+        crate::link_ui::paint(painter, &xf, i, info, doc_links, view, pointer);
+    }
+    if preparing {
+        crate::prepare::paint_page(tool_cx, form, view);
+        if let Some(preview) = &table_preview {
+            crate::field_table_ui::paint_preview(painter, &xf, i, preview);
+        }
+        if calc_order {
+            let selected = view.prepare.selected.as_ref().map(|(name, _)| name.as_str());
+            if let Some(field) = crate::calc_order_ui::paint_page(tool_cx, form, &view.calc_order, generation, selected) {
+                frame.calc_hover = Some(field);
+            }
+        }
+    } else {
+        crate::forms_ui::paint_page(painter, &xf, i, info, form, view, input.hover.as_ref());
+        crate::forms_ui::tooltip(resp, form, input.hover.as_ref());
+    }
+
+    // Form-field highlight (Acrobat's "Highlight existing fields"); required fields get a
+    // red border. Radio buttons and round XFA check boxes are round, and so is theirs (as
+    // in Acrobat). Only what can be filled is marked: a read-only widget (its field's, or a
+    // radio button's own) is left as it is drawn.
+    paint_field_highlights(painter, &xf, info, form.as_slice(), i, view.highlight_fields);
+    // Links: the hand and the link's target, which count only for the tools that follow or
+    // edit links (`Layer::reached_by`). Tips draw above the palette, so none shows while it is
+    // open, even beside it. A click follows the link its press was on, released over it: one that
+    // slips off the link first follows nothing, as a button's does.
+    if unobstructed
+        && resp.clicked()
+        && tool == QuickTool::Select
+        && !input.consumed
+        && let Some(Owner::Link { index }) = view.router.owner(i)
+        && input.released_over
+        && let Some(l) = info.links.iter().find(|l| l.page == i && l.index == index)
+    {
+        frame.out.clicked_link = Some(l.target.clone());
+    }
+    // Comments say what they are with any tool, beside its cursor, as Acrobat's do.
+    comments::describe(&pcx, view);
+    for (mp, mr, mc) in &view.compare_marks {
+        if *mp == i {
+            let sr = xf.user_rect(info, i, *mr).expand(1.5);
+            painter.rect_filled(sr, CornerRadius::same(2), mc.gamma_multiply(0.28));
+        }
+    }
+    if let Some((fp, fr, t0)) = view.flash
+        && fp == i
+    {
+        let now = ui.input(|inp| inp.time);
+        let t0 = if t0 == 0.0 { now } else { t0 };
+        view.flash = Some((fp, fr, t0));
+        let age = (now - t0) as f32;
+        if age < 1.6 {
+            let a = ((1.6 - age) / 1.6 * 255.0) as u8;
+            let sr = xf.user_rect(info, i, fr).expand(4.0);
+            painter.rect_stroke(
+                sr,
+                CornerRadius::same(3),
+                Stroke::new(2.5, Color32::from_rgba_unmultiplied(0x1B, 0x63, 0xE0, a)),
+                egui::StrokeKind::Outside,
+            );
+            ui.ctx().request_repaint();
+        } else {
+            view.flash = None;
+        }
+    }
+    // Validation is viewer chrome over the signer's original artwork, which
+    // may still say "Signature Not Verified". These badges never enter document
+    // streams, image/text exports, vector printing or Print as Image.
+    for badge in signature_badges(&doc.signatures, i) {
+        let [x0, y0, x1, y1] = badge.rect;
+        let sr = xf.user_rect(info, i, [x0 as f32, y0 as f32, x1 as f32, y1 as f32]);
+        let (icon, color) = crate::sign_ui::signature_status_style(badge.status);
+        painter.rect_stroke(sr, CornerRadius::same(2), Stroke::new(1.5, color), egui::StrokeKind::Outside);
+        // A widget too small for the mark keeps its outline: the verdict still shows.
+        if sr.width() < 4.0 || sr.height() < 4.0 {
+            continue;
+        }
+        // Big enough to read at a glance, small enough to leave the signer's own
+        // text visible around it.
+        let side = (sr.width().min(sr.height()) * 0.8).clamp(24.0, 192.0);
+        let mark = Rect::from_center_size(sr.center(), vec2(side, side));
+        icons::paint(ui, mark, icon, side * 0.64, color);
+        // Overlapping widgets paint in order, so the topmost badge's verdict is the tip, with
+        // any tool; a link's or a comment's tip wins over any badge.
+        if pointer.is_some_and(|p| mark.expand(2.0).contains(p)) {
+            view.cursor.describe(Subject::SignatureBadge, badge.summary.to_string());
+        }
+    }
+}
+
+fn paint_field_highlights(painter: &egui::Painter, xf: &PageXform, info: &DocInfo, form: &[pdfcraft_engine::FormField], page: usize, enabled: bool) {
+    if !enabled {
+        return;
+    }
+    for field in form.iter() {
+        let required = field.has(pdfcraft_engine::field_flags::REQUIRED);
+        for widget in field.widgets.iter().filter(|widget| widget.page == Some(page) && !widget.hidden && !widget.read_only) {
+            let rect = widget.rect;
+            let screen_rect = xf.user_rect(info, page, [rect[0] as f32, rect[1] as f32, rect[2] as f32, rect[3] as f32]);
+            let tint = Color32::from_rgba_unmultiplied(0x6E, 0x8E, 0xF5, 48);
+            let (width, color) = if required { (2.0, Color32::from_rgb(0xE3, 0x22, 0x22)) } else { (1.0, Color32::from_rgb(0x6E, 0x8E, 0xF5)) };
+            if widget.round {
+                let radius = screen_rect.width().min(screen_rect.height()) / 2.0;
+                painter.circle_filled(screen_rect.center(), radius, tint);
+                painter.circle_stroke(screen_rect.center(), radius - width / 2.0, Stroke::new(width, color));
+            } else {
+                painter.rect_filled(screen_rect, CornerRadius::same(1), tint);
+                painter.rect_stroke(screen_rect, CornerRadius::same(1), Stroke::new(width, color), egui::StrokeKind::Inside);
+            }
+        }
+    }
+}
+
+/// Escape while the pages hold a press abandons the gesture it drives, whichever tool's: nothing is
+/// placed, drawn, moved, resized or opened, and the press is ignored until the button is up. The
+/// frame of the release still belongs to the cancelled press.
+pub(super) fn cancel_on_escape(ctx: &egui::Context, view: &mut DocView, ptr: &PagePointer) {
+    // Over once the button is up and its release seen, or when a new press comes (its release and
+    // the next press can share a frame).
+    let new_press = matches!(ptr.edges.last(), Some(crate::page_pointer::Edge::Press(_)));
+    if view.press_cancelled && (new_press || !ptr.any_down && ptr.edges.is_empty()) {
+        view.press_cancelled = false;
+    }
+    if !view.press_cancelled && ptr.origin.is_some() && ptr.primary_down && ctx.input_mut(|i| i.consume_key(egui::Modifiers::NONE, egui::Key::Escape))
+    {
+        // A text selection being dragged goes with its drag: the markup, redaction or Replace
+        // Text that its end would make is not made.
+        if view.selection_drag {
+            view.clear_selection();
+        }
+        view.cancel_pointer_gestures();
+        view.press_cancelled = true;
+    }
+}

crates/ui-egui/src/canvas/page_pointer.rs

@@ -39,6 +39,9 @@ pub(crate) struct PagePointer {
     pub origin: Option<Pos2>,
     /// This frame's primary presses and releases of a press the pages hold, in order.
     pub edges: Vec<Edge>,
+    /// Where this frame's last primary release of a press the pages hold was: where a click came
+    /// up, which the pointer may have left by the frame's end. Kept past the cap on `edges`.
+    pub released: Option<Pos2>,
     /// The primary button is down, wherever it was pressed: a gesture ends once it is up.
     pub primary_down: bool,
     /// Some button is down, wherever it was pressed.
@@ -49,8 +52,16 @@ impl PagePointer {
     /// The pointer for `resp`, the content widget that holds every page, allocated in `ui`, while
     /// a dialog is open over the window or not (`modal`).
     pub(crate) fn read(ui: &egui::Ui, resp: &egui::Response, modal: bool) -> Self {
-        let (at, origin, edges, primary_down, any_down) =
-            ui.input(|i| (i.pointer.interact_pos(), i.pointer.press_origin(), edges(&i.events), i.pointer.primary_down(), i.pointer.any_down()));
+        let (at, origin, edges, released, primary_down, any_down) = ui.input(|i| {
+            (
+                i.pointer.interact_pos(),
+                i.pointer.press_origin(),
+                edges(&i.events),
+                last_release(&i.events),
+                i.pointer.primary_down(),
+                i.pointer.any_down(),
+            )
+        });
         // egui's own answer to "do the pages hold a press?": from the press on until the frame
         // of its click, release or drag stop. A drag can outlive egui's press while the
         // pointer is outside the window. With a dialog open only a drag counts, up to the frame
@@ -64,9 +75,9 @@ impl PagePointer {
             resp.dragged() || resp.drag_stopped() || (!modal && (resp.interact_pointer_pos().is_some() || press_origin.is_some_and(|p| on_top(&p))));
         let pos = at.filter(|p| held || on_top(p));
         if !held {
-            return Self { pos, origin: None, edges: Vec::new(), primary_down, any_down };
+            return Self { pos, origin: None, edges: Vec::new(), released: None, primary_down, any_down };
         }
-        Self { pos, origin: press_origin, edges, primary_down, any_down }
+        Self { pos, origin: press_origin, edges, released, primary_down, any_down }
     }
 
     /// Where the pointer is, when it is inside `r`.
@@ -97,6 +108,14 @@ fn first_press(edges: &[Edge]) -> Option<Pos2> {
     })
 }
 
+/// Where the last primary release among `events` was, however many came before it.
+fn last_release(events: &[Event]) -> Option<Pos2> {
+    events.iter().rev().find_map(|e| match e {
+        Event::PointerButton { pos, button: PointerButton::Primary, pressed: false, .. } if pos.is_finite() => Some(*pos),
+        _ => None,
+    })
+}
+
 /// The first [`MAX_EDGES`] primary presses and releases among `events`, in order.
 fn edges(events: &[Event]) -> Vec<Edge> {
     events

crates/ui-egui/src/canvas/page_pointer/tests.rs

@@ -53,6 +53,20 @@ fn a_touch_tap_keeps_its_position_on_the_frame_it_lifts() {
     assert_eq!(frame(&ctx, vec![], false), PagePointer::default(), "and forget it the frame after");
 }
 
+/// A click is located where it came up even after a stall's many presses and releases, past the
+/// cap on a frame's edges. Read from the edges kept, it was an earlier release's.
+#[test]
+fn a_frames_last_release_is_kept_past_the_cap_on_its_edges() {
+    let ctx = Context::default();
+    let (p, q) = (pos2(50.0, 60.0), pos2(80.0, 90.0));
+    frame(&ctx, vec![Event::PointerMoved(p)], false);
+    let mut events: Vec<Event> = (0..2 * MAX_EDGES).map(|i| button(p, PointerButton::Primary, i % 2 == 0)).collect();
+    events.extend([button(q, PointerButton::Primary, true), button(q, PointerButton::Primary, false)]);
+    let stall = frame(&ctx, events, false);
+    assert_eq!(stall.edges.len(), MAX_EDGES);
+    assert_eq!(stall.released, Some(q));
+}
+
 #[test]
 fn a_press_and_release_in_one_frame_keep_the_press() {
     let ctx = Context::default();
@@ -150,8 +164,9 @@ fn edges_are_primary_finite_in_order_and_capped() {
 }
 
 /// The page modules: the per-page chain in `canvas::document_area` and what it calls.
-const PAGE_MODULES: [&str; 35] = [
+const PAGE_MODULES: [&str; 37] = [
     "canvas.rs",
+    "canvas/page_input.rs",
     "canvas/area.rs",
     "canvas/bars.rs",
     "canvas/cache.rs",
@@ -186,8 +201,18 @@ const PAGE_MODULES: [&str; 35] = [
     "canvas/image_pick.rs",
     "canvas/signature_drag.rs",
     "tools/calc_order_ui.rs",
+    "tools/stamps_ui.rs",
 ];
 
+/// What a file that acts on the pages uses: the pointer, a tool's or the comments' page context,
+/// what a press is to a page, the router's hits and owners, or the router itself. Such a file is a
+/// page module. One that acts on the pages through the page view's response and a bare point alone
+/// uses none of them (`canvas/image_pick.rs`): PAGE_MODULES lists it by hand.
+const PAGE_MODULE_MARKS: [&str; 6] = ["PagePointer", "PageToolContext", "PageCx", "PagePress", "page_router::", ".router."];
+
+/// The router's own files, which define what page modules use.
+const ROUTER_FILES: [&str; 3] = ["canvas/page_pointer.rs", "canvas/page_router.rs", "canvas/page_cursor.rs"];
+
 /// egui's raw pointer state: where the pointer is, and which buttons are down or went down.
 const RAW_READS: [&str; 21] = [
     "hover_pos()",
@@ -216,14 +241,13 @@ const RAW_READS: [&str; 21] = [
 
 /// Functions in the page modules that are not page input and read egui's pointer state
 /// themselves: (file, function, why).
-const NOT_PAGE_INPUT: [(&str, &str, &str); 11] = [
+const NOT_PAGE_INPUT: [(&str, &str, &str); 10] = [
     ("canvas/area.rs", "zoom_anchor", "a pinch zooms the whole view, and is read before the pages' widget exists"),
     ("canvas/area.rs", "drawing_edge_pointer", "scrolls the view at its edges, read before the pages' widget exists"),
     ("canvas/area.rs", "glide_interrupted", "a press anywhere stops the touchpad's glide"),
     ("canvas/area.rs", "presentation_click", "full screen's click to turn the page, read before the pages' widget exists"),
     ("canvas/bars.rs", "page_size_hint", "the page size hint sits in the view's corner, not on a page"),
     ("canvas/organize.rs", "organize_grid", "Organize Pages shows thumbnails, not pages"),
-    ("tools/comments/input.rs", "keys", "keyboard handling after the pages: a drag cancelled with Escape ends once no button is down"),
     ("tools/forms_ui.rs", "overlay", "the field editor is an Area of its own over the page"),
     ("tools/content_ui.rs", "editor", "the added-text editor is an Area of its own over the page"),
     ("tools/edit_text_ui.rs", "overlay", "the paragraph editor is an Area of its own over the page"),
@@ -263,36 +287,131 @@ fn uses(line: &str, name: &str) -> bool {
     line.match_indices(name).any(|(at, _)| name.starts_with('.') || !line[..at].ends_with(|c: char| c.is_alphanumeric() || c == '_'))
 }
 
+/// The lines of `source` outside its test modules, numbered from 1. Tests drive egui's input and
+/// read its output themselves. A test module (`#[cfg(test)]` then `mod name {`) ends at the first
+/// line that is a lone `}`, as rustfmt lays a top-level item out, so the code after a test module
+/// in the middle of a file is still read; `#[cfg(test)]` then `mod name;` is one line.
+fn outside_test_modules(source: &str) -> Vec<(usize, &str)> {
+    let mut kept = Vec::new();
+    let mut lines = source.lines().enumerate().map(|(n, line)| (n + 1, line)).peekable();
+    while let Some((n, line)) = lines.next() {
+        if line == "#[cfg(test)]" && lines.peek().is_some_and(|(_, next)| next.starts_with("mod ")) {
+            if lines.next().is_some_and(|(_, module)| module.ends_with('{')) {
+                lines.by_ref().find(|(_, line)| *line == "}");
+            }
+            continue;
+        }
+        kept.push((n, line));
+    }
+    kept
+}
+
+/// The lines of code in `source` outside its test modules, numbered from 1, each with the
+/// top-level function or `impl` method it is in; comment lines are left out. A line rustfmt
+/// continued (a method chain split as `view` / `.router` / `.owner(i)`) is read with the one it
+/// continues, under that one's number.
+fn code_lines(source: &str) -> Vec<(usize, Option<&str>, String)> {
+    let (mut function, mut in_impl) = (None, false);
+    let mut lines: Vec<(usize, Option<&str>, String)> = Vec::new();
+    for (n, line) in outside_test_modules(source) {
+        if line.starts_with("impl") {
+            (function, in_impl) = (None, true);
+        } else if line == "}" {
+            (function, in_impl) = (None, false);
+        } else if let Some(name) = declares(line).or_else(|| line.strip_prefix("    ").filter(|_| in_impl).and_then(declares)) {
+            function = Some(name);
+        }
+        if line.trim_start().starts_with("//") {
+            continue;
+        }
+        match lines.last_mut() {
+            Some((_, _, text)) if line.trim_start().starts_with('.') => text.push_str(line.trim_start()),
+            _ => lines.push((n, function, line.to_owned())),
+        }
+    }
+    lines
+}
+
+/// Each name `find` finds in a line of the page modules' code (their tests left out), as (file,
+/// the top-level function or `impl` method it is in, line, name) ([`code_lines`]).
+fn page_module_matches(find: impl Fn(&str) -> Vec<String>) -> Vec<(&'static str, Option<String>, usize, String)> {
+    let src = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
+    let mut found = Vec::new();
+    for file in PAGE_MODULES {
+        let source = std::fs::read_to_string(src.join(file)).expect("page module").replace("\r\n", "\n");
+        for (n, function, text) in code_lines(&source) {
+            for name in find(&text) {
+                found.push((file, function.map(str::to_owned), n, name));
+            }
+        }
+    }
+    found
+}
+
+/// Each hit test `source` imports under a name that is not a hit test's (`use …::hit as under;`),
+/// as (name, alias), from each `use` statement, from its first line to its `;`, wherever it is.
+fn aliased_hit_tests(source: &str) -> Vec<(String, String)> {
+    let mut found = Vec::new();
+    let mut statement: Option<String> = None;
+    for line in source.lines().map(str::trim) {
+        if statement.is_none() && ["use ", "pub use ", "pub(crate) use ", "pub(super) use "].iter().any(|start| line.starts_with(start)) {
+            statement = Some(String::new());
+        }
+        let Some(text) = statement.as_mut() else { continue };
+        text.push_str(line);
+        text.push(' ');
+        if !line.ends_with(';') {
+            continue;
+        }
+        for part in text.split([',', '{', '}', ';']) {
+            let Some((path, alias)) = part.split_once(" as ") else { continue };
+            let (name, alias) = (path.trim().rsplit("::").next().unwrap_or_default(), alias.trim());
+            if is_hit_test(name) && !is_hit_test(alias) {
+                found.push((name.to_owned(), alias.to_owned()));
+            }
+        }
+        statement = None;
+    }
+    found
+}
+
+/// Each hit test a page module imports under a name that is not a hit test's, which the checks by
+/// name would not see ([`aliased_hit_tests`]).
+fn hit_test_aliases() -> Vec<String> {
+    let src = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
+    let mut found = Vec::new();
+    for file in PAGE_MODULES {
+        let source = std::fs::read_to_string(src.join(file)).expect("page module");
+        for (name, alias) in aliased_hit_tests(&source) {
+            found.push(format!(
+                "src/{file}: `{name} as {alias}` imports a hit test under another name, which the checks by name miss: name \
+                 it `hit` or `…_hit`."
+            ));
+        }
+    }
+    found
+}
+
+/// Each use of one of `names` in the page modules' code (their tests left out).
+fn page_module_uses(names: &[&str]) -> Vec<(&'static str, Option<String>, usize, String)> {
+    page_module_matches(|line| names.iter().filter(|name| uses(line, name)).map(|name| (*name).to_owned()).collect())
+}
+
 /// Each use of one of `names` in the page modules' code (their tests left out) outside the
 /// functions `allowed` to, as "src/file:line: `name` why"; then each allowed function that uses
 /// none of them any more, as "src/file: fn function unused".
 fn misuses(names: &[&str], allowed: &[(&str, &str, &str)], why: &str, unused: &str) -> Vec<String> {
-    let src = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
+    misuses_in(page_module_uses(names), allowed, why, unused)
+}
+
+/// [`misuses`], of what was `found`.
+fn misuses_in(found: Vec<(&str, Option<String>, usize, String)>, allowed: &[(&str, &str, &str)], why: &str, unused: &str) -> Vec<String> {
     let mut problems = Vec::new();
     let mut needed = vec![false; allowed.len()];
-    for file in PAGE_MODULES {
-        let source = std::fs::read_to_string(src.join(file)).expect("page module").replace("\r\n", "\n");
-        // Tests drive egui's input and read its output themselves.
-        let code = source.split("#[cfg(test)]\nmod ").next().unwrap_or_default();
-        // The top-level function, or method of an `impl`, that each line is in.
-        let (mut function, mut in_impl) = (None, false);
-        for (n, line) in code.lines().enumerate() {
-            if line.starts_with("impl") {
-                (function, in_impl) = (None, true);
-            } else if line == "}" {
-                (function, in_impl) = (None, false);
-            } else if let Some(name) = declares(line).or_else(|| line.strip_prefix("    ").filter(|_| in_impl).and_then(declares)) {
-                function = Some(name);
-            }
-            if line.trim_start().starts_with("//") {
-                continue;
-            }
-            for name in names.iter().filter(|name| uses(line, name)) {
-                match allowed.iter().position(|(f, function_name, _)| *f == file && function == Some(*function_name)) {
-                    Some(k) => needed[k] = true,
-                    None => problems.push(format!("src/{file}:{}: `{name}` {why}", n + 1)),
-                }
-            }
+    for (file, function, n, name) in found {
+        match allowed.iter().position(|(f, function_name, _)| *f == file && function.as_deref() == Some(*function_name)) {
+            Some(k) => needed[k] = true,
+            None => problems.push(format!("src/{file}:{n}: `{name}` {why}")),
         }
     }
     for ((file, name, _), needed) in allowed.iter().zip(needed) {
@@ -317,7 +436,7 @@ fn page_modules_read_the_pointer_only_through_page_pointer() {
          NOT_PAGE_INPUT there, with why.",
         "reads no pointer state any more: remove it from NOT_PAGE_INPUT.",
     );
-    // A module that takes the page pointer is a page module, so it is checked too.
+    // A module that acts on the pages is a page module, so it is checked too.
     let mut dirs = vec![src.clone()];
     while let Some(dir) = dirs.pop() {
         for entry in std::fs::read_dir(dir).expect("source directory") {
@@ -337,8 +456,9 @@ fn page_modules_read_the_pointer_only_through_page_pointer() {
             let file =
                 path.strip_prefix(&src).expect("under src").components().map(|c| c.as_os_str().to_string_lossy()).collect::<Vec<_>>().join("/");
             let source = std::fs::read_to_string(&path).expect("source file");
-            if file != "canvas/page_pointer.rs" && source.contains("PagePointer") && !PAGE_MODULES.contains(&file.as_str()) {
-                problems.push(format!("src/{file} takes the page pointer: add it to PAGE_MODULES."));
+            let marks = PAGE_MODULE_MARKS.iter().filter(|mark| source.contains(**mark)).collect::<Vec<_>>();
+            if !ROUTER_FILES.contains(&file.as_str()) && !marks.is_empty() && !PAGE_MODULES.contains(&file.as_str()) {
+                problems.push(format!("src/{file} uses {marks:?}, so it acts on the pages: add it to PAGE_MODULES."));
             }
         }
     }
@@ -362,18 +482,138 @@ fn page_modules_claim_the_cursor_and_never_set_it() {
     assert!(problems.is_empty(), "{}", problems.join("\n"));
 }
 
-/// Hit producers are called only by the central routing table, not again by an input handler.
-const PAGE_HIT_CALLS: [&str; 8] = [
+/// What decides, keeps or drops the press the pages hold.
+const ROUTER_WRITES: [&str; 8] = [
+    "router.begin(",
+    "router.press(",
+    "router.settle(",
+    "router.cancel(",
+    "PageRouter::begin(",
+    "PageRouter::press(",
+    "PageRouter::settle(",
+    "PageRouter::cancel(",
+];
+
+/// The functions that decide, keep or drop the press the pages hold: (file, function, why).
+const ROUTER_WRITERS: [(&str, &str, &str); 3] = [
+    ("canvas/page_input.rs", "page_tool_input", "the hits at the press point decide its owner, once per press"),
+    ("canvas.rs", "draw_pages", "the press is over once the button is up and its release seen, and a new one drops the last owner"),
+    ("canvas.rs", "cancel_pointer_gestures", "every pointer gesture's cancel: Escape, automation's cancel"),
+];
+
+/// Ways to make a `Hit`.
+const HIT_BUILDS: [&str; 2] = ["Hit::new(", "Hit {"];
+
+/// Whether `name` is a hit test's: `hit`, or `…_hit`.
+fn is_hit_test(name: &str) -> bool {
+    name == "hit" || name.ends_with("_hit")
+}
+
+/// The hit tests `line` calls: by path, bare or as a method.
+fn hit_test_calls(line: &str) -> Vec<String> {
+    line.match_indices("hit(")
+        .filter_map(|(at, _)| {
+            let end = at + "hit".len();
+            let start = line[..end].char_indices().rev().find(|(_, c)| !(c.is_alphanumeric() || *c == '_')).map_or(0, |(i, c)| i + c.len_utf8());
+            let (before, name) = (&line[..start], &line[start..end]);
+            (is_hit_test(name) && !before.ends_with("fn ")).then(|| name.to_owned())
+        })
+        .collect()
+}
+
+/// The functions that call a hit test: (file, function, why). Hit tests are found by name (a
+/// function named `hit` or `…_hit`, called by path, bare or as a method). The comments' point test
+/// has a list of its own (`COMMENT_POINT_TESTERS`); the others by other names (added content's,
+/// Edit text's paragraphs', Redact's text test, the text layer's links) are not listed yet, and
+/// most are PR 4b's. `PageHits::hits` is the one: the hits
+/// at the press point decide its owner, and those under the pointer give its cursor, its tip, hover
+/// painting and a right-click.
+const HIT_TESTERS: [(&str, &str, &str); 1] = [(
+    "canvas/page_input.rs",
+    "hits",
+    "`PageHits::hits`: every module's hits at a point, for the pointer's cursor and tip, a right-click and, once, the press's owner",
+)];
+
+/// The page view's asks for every module's hits at a point (`PageHits::hits`, and `at` and
+/// `context_at`, which wrap it).
+const PAGE_HITS_ASKS: [&str; 6] = [".hits(", ".at(", ".context_at(", "PageHits::hits(", "PageHits::at(", "PageHits::context_at("];
+
+/// The functions that ask the page view's hits at a point: (file, function, why). `PageHits` is
+/// private to `page_input.rs`, so this keeps a new function there from asking; a second ask inside
+/// a listed function is for review to catch. The method names are matched in every page module,
+/// so an `at` of another type there would need them narrowed.
+const PAGE_HITS_ASKERS: [(&str, &str, &str); 5] = [
+    ("canvas/page_input.rs", "at", "`PageHits::at`: the hits at a point, as a press there would take them"),
+    ("canvas/page_input.rs", "context_at", "`PageHits::context_at`: what a right-click at a point is on"),
+    (
+        "canvas/page_input.rs",
+        "page_tool_input",
+        "the hits at the press point decide its owner, once per press; those under the pointer before the tools act, once a \
+         frame, serve a click's release, a right-click and Fill & Sign's preview",
+    ),
+    ("canvas/page_input.rs", "claim_under", "what lies under the pointer after the tools act: its cursor, its tip and hover painting"),
+    ("canvas/page_input.rs", "right_click", "what a right-click is on"),
+];
+
+/// The comments' point test, which their hit tests are built on: which comment lies under a point.
+const COMMENT_POINT_TESTS: [&str; 2] = [".comment_at(", "PageCx::comment_at("];
+
+/// The functions that ask which comment lies under a point: (file, function, why).
+const COMMENT_POINT_TESTERS: [(&str, &str, &str); 3] = [
+    ("tools/comments/input.rs", "hit", "the comments' hit test"),
+    ("tools/comments/input.rs", "context_hit", "the comments' hit test for a right-click"),
+    ("tools/comments/paint.rs", "paint_page", "a redaction mark shows its fill under the pointer with every tool, as comments' tips show"),
+];
+
+/// What reads who holds the press the pages hold.
+const ROUTER_READS: [&str; 6] =
+    ["router.press_for(", "router.owner(", "router.keeps_drag(", "PageRouter::press_for(", "PageRouter::owner(", "PageRouter::keeps_drag("];
+
+/// The functions that read who holds the press: (file, function, why). The page view asks once per
+/// page and tells each module what the press is to its page (`PagePress`); the Edit text group, the
+/// text layer and link following still ask, until they are told too (PR 4b), and an unused entry
+/// fails the test.
+const ROUTER_READERS: [(&str, &str, &str); 8] = [
+    (
+        "canvas/page_input.rs",
+        "page_tool_input",
+        "the page view: what the press is to each page (`press_for`); Add text's paragraph and the pictures until 4b",
+    ),
+    ("canvas/page_input.rs", "update_selection_on_press", "the text layer selects no text under a press held by what keeps its drag (4b)"),
+    ("canvas/page_input.rs", "finish_text_pointer_gesture", "a click held by what keeps its drag leaves the text selection alone (4b)"),
+    ("canvas/page_input.rs", "page_overlays", "a click follows the link that holds its press (4b)"),
+    ("tools/content_ui.rs", "page_input", "added text and pictures, until they are told (4b)"),
+    ("tools/edit_text_ui.rs", "page_input", "Edit text's paragraphs, until they are told (4b)"),
+    ("tools/edit_text_ui/image.rs", "image_input", "Edit text's pictures, until they are told (4b)"),
+    ("tools/object_ui.rs", "input", "the objects selected together, until they are told (4b)"),
+];
+
+/// What ignores the press the pages hold until the button is up.
+const PRESS_IGNORES: [&str; 1] = ["press_cancelled = true"];
+
+/// The one function that ignores a press until the button is up: (file, function, why).
+const PRESS_IGNORERS: [(&str, &str, &str); 1] =
+    [("canvas/page_input.rs", "cancel_on_escape", "Escape abandons the gesture the press drives, whichever tool's")];
+
+/// The module hit tests, called by path: a press handler calls none of them (HIT_TESTERS says who
+/// may).
+const PAGE_HIT_CALLS: [&str; 12] = [
+    "link_ui::hit(",
     "prepare::hit(",
     "forms_ui::hit(",
     "comments::hit(",
+    "comments::context_hit(",
+    "camera_ui::hit(",
     "edit_text_ui::hit(",
     "edit_text_ui::picture_hit(",
     "edit_text_ui::picture_handle_hit(",
+    "edit_text_ui::crop_hit(",
     "object_ui::hit(",
     "content_ui::hit(",
 ];
 
+/// Whether a press handler's `code` acts on the owner the router captured, and calls no hit test
+/// of its own to choose one.
 fn routed_press_handler(code: &str) -> bool {
     let code = code.lines().filter(|line| !line.trim_start().starts_with("//")).collect::<Vec<_>>().join("\n");
     code.contains("router.owner(")
@@ -383,51 +623,161 @@ fn routed_press_handler(code: &str) -> bool {
         && !uses(&code, "handle_hit(")
 }
 
-/// Source-level guard for the Page presses rule, alongside the raw-pointer and cursor guards.
-/// Runtime routing, capture lifetime and Escape behavior have separate behavioral tests.
+/// Page modules act on a press only when the router says it is theirs. The hits at the press
+/// point decide its owner once, in one place, and a `Hit` comes only from a module's hit test,
+/// so what the cursor promised is what the press does. Where each module tested the press
+/// point again, or asked another whether it wanted the press, the answers disagreed: a press on
+/// one check box released over the next ticked the second, and a drag could be taken over
+/// halfway. Only `PageHits::hits` asks the hit tests. Escape is the one way to
+/// drop a press and ignore it until the button is up.
 #[test]
-fn page_modules_take_presses_from_the_router_without_repeating_hit_tests() {
+fn page_modules_act_on_a_press_only_through_the_router() {
     let mut problems = misuses(
-        &PAGE_HIT_CALLS,
-        &[("canvas.rs", "at", "the central PageHits table")],
-        "repeats a module hit test outside PageHits::at; use the captured router owner",
-        "no longer collects module hits",
+        &ROUTER_WRITES,
+        &ROUTER_WRITERS,
+        "decides, keeps or drops the press the pages hold. Only the hits at the press point decide its owner, once \
+         (src/canvas/page_router.rs), and the page view tells each module what the press is to its page (`PagePress`). Drop a press with \
+         `DocView::cancel_pointer_gestures`. A new place that must? Add the function to ROUTER_WRITERS in \
+         src/canvas/page_pointer/tests.rs, with why.",
+        "no longer decides, keeps or drops the press: remove it from ROUTER_WRITERS.",
     );
     problems.extend(misuses(
-        &["router.press("],
-        &[("canvas.rs", "page_tool_input", "the central press capture")],
-        "captures a page press outside the central routing path",
-        "no longer captures page presses",
+        &ROUTER_READS,
+        &ROUTER_READERS,
+        "reads who holds the press the pages hold. The page view asks the router once per page and tells each module \
+         what the press is to its page: take a `PagePress` (src/canvas/page_router.rs) instead. A new place that must? \
+         Add the function to ROUTER_READERS in src/canvas/page_pointer/tests.rs, with why.",
+        "no longer reads who holds the press: remove it from ROUTER_READERS.",
+    ));
+    // A router method the lists above don't name yet is the router's all the same: only their
+    // functions use it.
+    let known: Vec<&str> = ROUTER_WRITES.iter().chain(ROUTER_READS.iter()).copied().collect();
+    let unlisted = page_module_matches(|line| {
+        let router = uses(line, ".router.") || uses(line, "PageRouter::");
+        if router && !known.iter().any(|name| uses(line, name)) { vec!["router".to_owned()] } else { Vec::new() }
+    });
+    problems.extend(
+        unlisted
+            .into_iter()
+            .filter(|(file, function, _, _)| {
+                !ROUTER_WRITERS.iter().chain(ROUTER_READERS.iter()).any(|(f, name, _)| f == file && function.as_deref() == Some(*name))
+            })
+            .map(|(file, _, n, _)| {
+                format!(
+                    "src/{file}:{n}: uses the router by a method ROUTER_WRITES and ROUTER_READS don't name. The page view \
+                     decides the press and tells each module what it is to its page (`PagePress`): add the method to \
+                     ROUTER_WRITES or ROUTER_READS in src/canvas/page_pointer/tests.rs, and the function to their lists \
+                     only if it must."
+                )
+            }),
+    );
+    problems.extend(misuses(
+        &COMMENT_POINT_TESTS,
+        &COMMENT_POINT_TESTERS,
+        "asks which comment lies under a point. The comments' hit tests answer that for a press and a right-click: \
+         act on what the page view tells you, rather than testing the point again. A new place that must? Add the \
+         function to COMMENT_POINT_TESTERS in src/canvas/page_pointer/tests.rs, with why.",
+        "no longer asks which comment lies under a point: remove it from COMMENT_POINT_TESTERS.",
+    ));
+    problems.extend(misuses(
+        &PAGE_HITS_ASKS,
+        &PAGE_HITS_ASKERS,
+        "asks the page view's hits at a point. The hits at the press point decide its owner once, and those under the \
+         pointer are taken once before the tools act and once after: use those (`under`, `PageInput.hover`). A new \
+         place that must ask? Add the function to PAGE_HITS_ASKERS in src/canvas/page_pointer/tests.rs, with why.",
+        "no longer asks the page view's hits: remove it from PAGE_HITS_ASKERS.",
+    ));
+    problems.extend(misuses(
+        &PRESS_IGNORES,
+        &PRESS_IGNORERS,
+        "ignores the press the pages hold. Escape cancels a press, in `cancel_on_escape`: drop a gesture with \
+         `DocView::cancel_pointer_gestures` instead.",
+        "no longer ignores a press: remove it from PRESS_IGNORERS.",
     ));
     let src = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
     for (file, function) in [
-        ("tools/forms_ui.rs", "page_input"),
-        ("tools/prepare.rs", "page_input"),
         ("tools/content_ui.rs", "page_input"),
         ("tools/edit_text_ui.rs", "page_input"),
         ("tools/edit_text_ui/image.rs", "image_input"),
         ("tools/object_ui.rs", "input"),
-        ("tools/comments/input.rs", "select_input"),
     ] {
         let source = std::fs::read_to_string(src.join(file)).expect("page input module");
         let body = source.lines().skip_while(|line| declares(line) != Some(function)).take_while(|line| *line != "}").collect::<Vec<_>>().join("\n");
-        // Forms reuse their hit test for hover text and to require release over the captured
-        // widget. Neither chooses the press owner. Pin both calls to the current pointer `p`,
-        // not the press origin, and reject an additional call or a changed argument.
-        let body = if file == "tools/forms_ui.rs" {
-            let call = "hit(xf, info, page, form, allowed, p)";
-            assert_eq!(body.matches(call).count(), 2, "only the existing hover and release checks are exempt");
-            body.replace(call, "hover_or_release_check")
-        } else {
-            body
-        };
         if !routed_press_handler(&body) {
             problems.push(format!("src/{file}: {function} must consume the captured router owner without repeating a hit test"));
         }
     }
+    // A hit test is a function named `hit` or `…_hit`: one answer to "what of mine is here?",
+    // which gives the module's cursor, its tip and its press.
+    problems.extend(misuses_in(
+        page_module_matches(hit_test_calls),
+        &HIT_TESTERS,
+        "calls a hit test. The hits at the press point decide its owner once, in `PageHits::hits`: act on the press when \
+         the page view tells you it is yours (`PagePress::Mine`), rather than testing its point again. What lies under \
+         the pointer comes from the page view's own hits: hover painting and tips (`PageInput.hover`), a click released \
+         over what it was pressed on (`released_over`). A new place that must ask? Add the function to HIT_TESTERS in \
+         src/canvas/page_pointer/tests.rs, with why.",
+        "calls no hit test any more: remove it from HIT_TESTERS.",
+    ));
+    problems.extend(hit_test_aliases());
+    // An entry no page module calls any more no longer guards anything.
+    let called = page_module_uses(&PAGE_HIT_CALLS);
+    problems.extend(
+        PAGE_HIT_CALLS
+            .iter()
+            .filter(|call| !called.iter().any(|(_, _, _, name)| name == *call))
+            .map(|call| format!("no page module calls `{call}` any more: remove it from PAGE_HIT_CALLS.")),
+    );
+    let builds = page_module_uses(&HIT_BUILDS);
+    assert!(!builds.is_empty(), "no page module makes a `Hit` any more: update HIT_BUILDS");
+    problems.extend(builds.into_iter().filter(|(_, function, _, _)| !function.as_deref().is_some_and(is_hit_test)).map(|(file, _, n, name)| {
+        format!(
+            "src/{file}:{n}: `{name}` makes a hit outside a hit test. A page module answers \"what of mine is \
+                     here?\" in one function, named `hit` or `…_hit`, so its cursor, its tip and its press agree."
+        )
+    }));
     assert!(problems.is_empty(), "{}", problems.join("\n"));
 }
 
+/// A test module in the middle of a file hides only itself from the page guards: the code after
+/// it is read too. The guards used to stop at the first test module.
+#[test]
+fn the_page_guards_read_past_a_test_module_in_the_middle_of_a_file() {
+    let source = "fn before() {}\n#[cfg(test)]\nmod tests {\n    fn inside() {}\n}\n\nfn after() {}\n#[cfg(test)]\nmod more;\nfn last() {}\n";
+    let kept: Vec<(usize, &str)> = outside_test_modules(source);
+    assert_eq!(kept, [(1, "fn before() {}"), (6, ""), (7, "fn after() {}"), (10, "fn last() {}")]);
+}
+
+/// The guard's readers: hit tests by name, the function a line declares, a call rustfmt split,
+/// and a hit test imported as another name.
+#[test]
+fn the_page_guards_read_hit_tests_split_calls_and_aliases() {
+    assert_eq!(hit_test_calls("let h = crate::forms_ui::hit(xf, p);"), ["hit"]);
+    assert_eq!(hit_test_calls("cx.comment_hit(p) && picture_hit(p)"), ["comment_hit", "picture_hit"]);
+    assert!(hit_test_calls("pub(crate) fn hit(xf: &PageXform) -> Option<Hit> {").is_empty());
+    assert!(hit_test_calls("let all = self.hits(view, p, false);").is_empty());
+    assert_eq!(declares("pub(crate) const fn crop_hit<'a>(view: &DocView) {"), Some("crop_hit"));
+    assert_eq!(declares("let hit = 1;"), None);
+    let source = "impl PageHits<'_> {\n    fn at(&self) {\n        self\n            .hits(view, p, false)\n    }\n}\nfn after() {\n    // view.router.owner(0)\n    let _ = view\n        .router\n        .owner(0);\n}\n";
+    assert_eq!(
+        code_lines(source),
+        [
+            (1, None, "impl PageHits<'_> {".to_owned()),
+            (2, Some("at"), "    fn at(&self) {".to_owned()),
+            (3, Some("at"), "        self.hits(view, p, false)".to_owned()),
+            (5, Some("at"), "    }".to_owned()),
+            (6, None, "}".to_owned()),
+            (7, Some("after"), "fn after() {".to_owned()),
+            (9, Some("after"), "    let _ = view.router.owner(0);".to_owned()),
+            (12, None, "}".to_owned()),
+        ]
+    );
+    let source =
+        "fn a() {}\n\n#[cfg(any())]\nuse crate::camera_ui::hit as corner_under;\nuse crate::x::{\n    hit as x_hit,\n    picture_hit as under,\n};\n";
+    let aliases: Vec<(String, String)> = [("hit", "corner_under"), ("picture_hit", "under")].map(|(a, b)| (a.to_owned(), b.to_owned())).to_vec();
+    assert_eq!(aliased_hit_tests(source), aliases);
+}
+
 #[test]
 fn the_page_press_guard_rejects_missing_owners_and_second_hit_tests() {
     assert!(routed_press_handler("let owner = view.router.owner(page);"));

crates/ui-egui/src/canvas/page_router.rs

@@ -6,7 +6,8 @@
 //! press point decide who captures it ([`PageRouter::press`]), by the same table: the highest layer
 //! the active tool reaches. Until the button is up only the owner acts on the press, its drag and
 //! its release, so what the cursor promised is what the press does, and nothing takes a gesture
-//! back halfway.
+//! back halfway. Each page is told what it has to do with the press ([`PagePress`]): its owner's,
+//! the active tool's, or none of its business.
 
 use egui::CursorIcon;
 
@@ -18,7 +19,7 @@ use crate::page_cursor::Layer;
 pub(crate) enum Owner {
     /// A comment (or a Fill & Sign mark), by its `/Annots` index, and the part of it.
     Comment { index: usize, part: CommentPart },
-    /// A link, by its index in the document's links.
+    /// A link, by its index in its page's `/Annots`.
     Link { index: usize },
     /// A form field's widget, by the field's index in the form and the widget's in the field.
     Field { field: usize, widget: usize },
@@ -35,6 +36,8 @@ pub(crate) enum Owner {
     /// Added text or a picture placed on the page, by its index among the page's, and a corner of
     /// the selected one (left, top) or the item itself.
     Added { index: usize, corner: Option<(bool, bool)> },
+    /// Enhance ▸ Camera image: a corner of the quadrilateral (0 left top, then clockwise).
+    CameraCorner { corner: usize },
 }
 
 /// The part of a picture a hit is on.
@@ -87,7 +90,7 @@ pub(crate) struct Hit {
     /// Beside the pointer where this hit wins (a link's target).
     pub tip: Option<String>,
     /// A drag from here is not this owner's: a click on a highlight selects it, a drag across it
-    /// selects the text underneath.
+    /// selects the text underneath; with the Link tool, a drag from a link draws a new one.
     pub declines_drag: bool,
 }
 
@@ -106,10 +109,35 @@ pub(crate) fn top(hits: impl IntoIterator<Item = Hit>, tool: QuickTool) -> Optio
     })
 }
 
+/// What one page has to do with the press the pages hold.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum PagePress {
+    /// The press began on this page, and the owner's hit won it: its module acts on it. Others
+    /// only let go of their own state (a click on anything but the selected comment unselects it).
+    Mine(Owner),
+    /// No button is down, or the press began on this page and nobody's hit won it: the active
+    /// tool's. Also every page's while a press the page view does not hold is down (one that began
+    /// over a panel), and after the press was dropped ([`PageRouter::cancel`]) until the button is
+    /// up (`Elsewhere` instead when Escape came in the press's own frame; page input skips a
+    /// cancelled press either way).
+    Free,
+    /// The press began on another page, or off the pages (between them, or beside one).
+    Elsewhere,
+}
+
+impl PagePress {
+    /// Who holds the press on this page, if anyone.
+    pub(crate) fn owner(self) -> Option<Owner> {
+        match self {
+            PagePress::Mine(owner) => Some(owner),
+            PagePress::Free | PagePress::Elsewhere => None,
+        }
+    }
+}
+
 /// A press the pages hold, and who it belongs to.
 #[derive(Clone, Debug, PartialEq)]
 pub(crate) struct Capture {
-    pub page: usize,
     pub owner: Owner,
     pub declines_drag: bool,
 }
@@ -118,18 +146,43 @@ pub(crate) struct Capture {
 #[derive(Debug, Default)]
 pub(crate) struct PageRouter {
     capture: Option<Capture>,
+    /// A press is held, and the page it began on (`None`: off the pages, between them or beside one).
+    began: Option<Option<usize>>,
 }
 
 impl PageRouter {
+    /// A new press on the pages: the last one's owner goes, and until a page claims it the press is
+    /// between the pages.
+    pub(crate) fn begin(&mut self) {
+        self.capture = None;
+        self.began = Some(None);
+    }
+
     /// A press on `page`: `hits` at the press point decide who it belongs to. A press nobody's
     /// hit claims is held by nobody (the page's text, or a tool that acts anywhere on the page).
+    /// Only a press just begun ([`Self::begin`]) is claimed, by the first page that does: pages
+    /// that touch (the gaps hidden) can share a row of pixels, and a press there is one page's.
     pub(crate) fn press(&mut self, page: usize, hits: impl IntoIterator<Item = Hit>, tool: QuickTool) {
-        self.capture = top(hits, tool).map(|h| Capture { page, owner: h.owner, declines_drag: h.declines_drag });
+        if self.began != Some(None) {
+            return;
+        }
+        self.capture = top(hits, tool).map(|h| Capture { owner: h.owner, declines_drag: h.declines_drag });
+        self.began = Some(Some(page));
+    }
+
+    /// What `page` has to do with the press the pages hold.
+    pub(crate) fn press_for(&self, page: usize) -> PagePress {
+        match (self.began, &self.capture) {
+            (None, _) => PagePress::Free,
+            (Some(Some(p)), Some(capture)) if p == page => PagePress::Mine(capture.owner),
+            (Some(Some(p)), None) if p == page => PagePress::Free,
+            _ => PagePress::Elsewhere,
+        }
     }
 
     /// Who holds the press on `page`.
     pub(crate) fn owner(&self, page: usize) -> Option<Owner> {
-        self.capture.as_ref().filter(|c| c.page == page).map(|c| c.owner)
+        self.press_for(page).owner()
     }
 
     /// Whether the press is held by someone who keeps its drag: then the page's text is not
@@ -142,12 +195,15 @@ impl PageRouter {
     pub(crate) fn settle(&mut self, any_down: bool, edges: bool) {
         if !any_down && !edges {
             self.capture = None;
+            self.began = None;
         }
     }
 
-    /// Drops the press (Escape, a dialog, automation's cancel).
+    /// Drops the press (Escape, automation's cancel): every page is the active tool's again
+    /// ([`PagePress::Free`]). Page input skips a press Escape cancelled until the button is up.
     pub(crate) fn cancel(&mut self) {
         self.capture = None;
+        self.began = None;
     }
 }
 
@@ -172,6 +228,7 @@ mod tests {
     #[test]
     fn a_press_is_held_until_the_button_is_up_and_its_release_seen() {
         let mut r = PageRouter::default();
+        r.begin();
         r.press(2, [hit(Layer::Comment, 7)], QuickTool::Select);
         assert_eq!(r.owner(2), Some(hit(Layer::Comment, 7).owner));
         assert_eq!(r.owner(1), None, "only on its page");
@@ -180,14 +237,49 @@ mod tests {
         assert!(r.owner(2).is_some(), "the release frame still belongs to the press");
         r.settle(false, false);
         assert_eq!(r.owner(2), None);
+        r.begin();
         r.press(0, [], QuickTool::Select);
         assert_eq!(r.owner(0), None, "a press nobody claims is held by nobody");
         assert!(!r.keeps_drag());
     }
 
+    /// A page is told whether the press is its owner's, the active tool's, or another page's.
+    #[test]
+    fn each_page_is_told_whether_the_press_is_its_own() {
+        let mut r = PageRouter::default();
+        assert_eq!(r.press_for(3), PagePress::Free, "no button down: every page is the tool's");
+        r.begin();
+        assert_eq!(r.press_for(0), PagePress::Elsewhere, "a press between the pages is no page's");
+        r.press(2, [], QuickTool::Select);
+        assert_eq!((r.press_for(2), r.press_for(1)), (PagePress::Free, PagePress::Elsewhere), "nobody's, on page 2");
+        r.begin();
+        r.press(1, [hit(Layer::Comment, 4)], QuickTool::Select);
+        assert_eq!((r.press_for(1), r.press_for(2)), (PagePress::Mine(hit(Layer::Comment, 4).owner), PagePress::Elsewhere));
+        r.settle(false, true);
+        assert_eq!(r.press_for(2), PagePress::Elsewhere, "until its release has been seen");
+        r.settle(false, false);
+        assert_eq!((r.press_for(1), r.press_for(2)), (PagePress::Free, PagePress::Free));
+        r.begin();
+        r.cancel();
+        // Page input skips a press Escape cancelled until the button is up (`press_cancelled`).
+        assert_eq!(r.press_for(0), PagePress::Free, "a cancelled press leaves every page to the tool");
+    }
+
+    /// Pages that touch (the gaps hidden) can share a row of pixels: a press there is the first
+    /// page's to claim it, and the next page's claim is ignored.
+    #[test]
+    fn a_press_where_two_pages_touch_is_the_first_pages() {
+        let mut r = PageRouter::default();
+        r.begin();
+        r.press(0, [hit(Layer::Comment, 1)], QuickTool::Select);
+        r.press(1, [hit(Layer::Comment, 2)], QuickTool::Select);
+        assert_eq!((r.press_for(0), r.press_for(1)), (PagePress::Mine(hit(Layer::Comment, 1).owner), PagePress::Elsewhere));
+    }
+
     #[test]
     fn a_highlight_lets_its_drag_go_to_the_text() {
         let mut r = PageRouter::default();
+        r.begin();
         r.press(0, [Hit { declines_drag: true, ..hit(Layer::Comment, 0) }], QuickTool::Select);
         assert!(r.owner(0).is_some() && !r.keeps_drag());
         r.cancel();

crates/ui-egui/src/canvas/signature_drag.rs

@@ -402,8 +402,7 @@ mod tests {
         let doc = session.get(id).expect("open");
         let index = doc.info.annotations.iter().find(|a| a.subtype == "Sound").expect("listed").index;
         let ctx = egui::Context::default();
-        let mut cv = CommentView::default();
-        cv.gesture = Some(Gesture::Move { page: 0, index, from: pos2(0.0, 0.0) });
+        let mut cv = CommentView { gesture: Some(Gesture::Move { page: 0, index, from: pos2(0.0, 0.0) }), ..CommentView::default() };
         let mut drag = SignatureDrag::default();
         let key = Some((doc.edit_generation(), 0, index));
         drag.prepare_move(&ctx, doc, &cv, None, false, 1.0);

crates/ui-egui/src/canvas/tests.rs

@@ -2359,3 +2359,24 @@ fn image_handles_account_for_document_and_view_rotation() {
         }
     }
 }
+
+/// Cancelling the pages' pointer gestures (Escape, automation's cancel) lets go of a
+/// camera corner being dragged: the quadrilateral stays, and no corner follows the pointer.
+#[test]
+fn cancelling_pointer_gestures_lets_go_of_a_camera_corner() {
+    let mut v = view(1, PageLayout::Single, true);
+    v.camera = Some(crate::camera_ui::CameraQuad { grab: Some(2), ..crate::camera_ui::CameraQuad::inset(0, 300.0, 400.0) });
+    v.cancel_pointer_gestures();
+    assert_eq!(v.camera.map(|q| q.grab), Some(None));
+}
+
+/// A camera corner at the page's edge is hit on the page only: a press off the page is no page's,
+/// so its grab cursor does not show there.
+#[test]
+fn a_camera_corner_at_the_page_edge_is_hit_on_the_page_only() {
+    let mut v = view(1, PageLayout::Single, true);
+    v.camera = Some(crate::camera_ui::CameraQuad { page: 0, corners: [[0.0, 0.0], [300.0, 0.0], [300.0, 400.0], [0.0, 400.0]], grab: None });
+    let xf = PageXform { rect: Rect::from_min_size(pos2(10.0, 20.0), egui::vec2(300.0, 400.0)), rot: 0, pw: 300.0, ph: 400.0 };
+    assert!(crate::camera_ui::hit(&xf, 0, &v, pos2(14.0, 24.0)).is_some(), "on the page");
+    assert!(crate::camera_ui::hit(&xf, 0, &v, pos2(6.0, 16.0)).is_none(), "just off it");
+}

crates/ui-egui/src/canvas/zoom_snap.rs

@@ -13,15 +13,15 @@ use crate::{PdfCraftApp, QuickTool};
 /// [x0, y0, x1, y1]); a plain click has an empty rectangle.
 pub type Marquee = (usize, Rect, [f32; 4]);
 
-/// Drag a rectangle on page `page` (Marquee Zoom, Snapshot).
-pub(crate) fn page_input(ui: &egui::Ui, resp: &egui::Response, xf: &PageXform, ptr: &PagePointer, page: usize, view: &mut DocView) {
+/// Drag a rectangle on page `page` (Marquee Zoom, Snapshot), with a press nobody holds (`free`).
+pub(crate) fn page_input(ui: &egui::Ui, resp: &egui::Response, xf: &PageXform, ptr: &PagePointer, page: usize, free: bool, view: &mut DocView) {
     let (pointer, origin) = (ptr.pos, ptr.origin);
     if pointer.is_some_and(|p| xf.rect.contains(p)) {
         view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
     }
-    // The tool's own press, of the primary button: nothing drawn over the page here holds it.
+    // The tool's own press, of the primary button: one nobody holds.
     if resp.drag_started_by(egui::PointerButton::Primary)
-        && view.router.owner(page).is_none()
+        && free
         && let Some(o) = origin.filter(|o| xf.rect.contains(*o))
     {
         view.marquee = Some((page, o));
@@ -40,7 +40,8 @@ pub(crate) fn page_input(ui: &egui::Ui, resp: &egui::Response, xf: &PageXform, p
             view.marquee_done = Some((page, r, [a.0.min(b.0), a.1.min(b.1), a.0.max(b.0), a.1.max(b.1)]));
         }
     }
-    if resp.clicked()
+    if free
+        && resp.clicked()
         && let Some(p) = pointer.filter(|p| xf.rect.contains(*p))
     {
         let v = xf.screen_to_view(p);

crates/ui-egui/src/dialogs/marks_ui.rs

@@ -3,6 +3,8 @@
 //! page the range selects, with the marks laid out on it. "Update" opens the same dialog in
 //! replace mode.
 
+#[cfg(not(target_arch = "wasm32"))]
+use crate::file_filter::AddFilterAnyCase as _;
 use std::collections::{HashMap, HashSet};
 
 use egui::{Align, Color32, CornerRadius, Layout, Rect, Stroke, pos2, vec2};
@@ -777,7 +779,7 @@ pub(crate) fn body(ui: &mut egui::Ui, app: &mut PdfCraftApp, t: &Tokens, kind: M
     #[cfg(not(target_arch = "wasm32"))]
     if browse {
         let dialog = rfd::AsyncFileDialog::new()
-            .add_filter(tl!("PDF or image"), &["pdf", "png", "jpg", "jpeg", "tif", "tiff", "gif", "bmp", "jp2", "j2k", "jpx"]);
+            .add_filter_any_case(tl!("PDF or image"), &["pdf", "png", "jpg", "jpeg", "tif", "tiff", "gif", "bmp", "jp2", "j2k", "jpx"]);
         let epoch = app.dialog_epoch();
         app.ask_one(crate::pickers::Ask::File(dialog), None, move |app, p| {
             // Only into the dialog that asked: not one closed meanwhile, or opened again since.

crates/ui-egui/src/editing.rs

@@ -977,6 +977,23 @@ impl PdfCraftApp {
                 let at = parent[parent.len() - 1] + 1;
                 Edit::MoveBookmark { from: path, to_parent: grand, index: at }
             }
+            A::Copy(path) => {
+                self.copy_bookmark(id, &path);
+                return;
+            }
+            A::Cut(path) => match self.copy_bookmark(id, &path) {
+                Some(false) => Edit::DeleteBookmark { path },
+                // Paste could not bring back what the copy left out, so the bookmarks stay.
+                Some(true) => {
+                    self.notify_tr("Bookmarks nested too deep to list could not be copied, so nothing was cut.");
+                    return;
+                }
+                None => return,
+            },
+            A::Paste { parent, index } => {
+                self.paste_bookmarks(id, parent, index);
+                return;
+            }
             A::FromStructure => {
                 self.right = Some(crate::RightPanel::Bookmarks);
                 Edit::BookmarksFromStructure
@@ -991,6 +1008,45 @@ impl PdfCraftApp {
     }
 }
 
+impl PdfCraftApp {
+    /// Put the bookmark at `path` and its subtree on the bookmark clipboard. `Some(true)` when
+    /// bookmarks nested too deep to list were left out; `None` if it could not be read (the reason
+    /// is shown).
+    fn copy_bookmark(&mut self, id: pdfcraft_engine::DocId, path: &[usize]) -> Option<bool> {
+        match self.session.outline_tree(id, path) {
+            Some(Ok(tree)) => {
+                if tree.truncated {
+                    self.notify_tr("Bookmarks nested too deep to list were left out of the copy.");
+                }
+                self.bookmark_clipboard = Some(tree.nodes);
+                Some(tree.truncated)
+            }
+            Some(Err(e)) => {
+                self.notify_error(e);
+                None
+            }
+            None => None,
+        }
+    }
+
+    /// Paste the bookmark clipboard as one undoable edit. Bookmarks whose page this document lacks
+    /// arrive without a destination, and the toast says how many.
+    fn paste_bookmarks(&mut self, id: pdfcraft_engine::DocId, parent: Vec<usize>, index: usize) {
+        let Some(bookmarks) = self.bookmark_clipboard.clone() else { return };
+        let pages = self.session.get(id).map_or(0, |d| d.info.pages.len());
+        let unmapped = pdfcraft_engine::outline_unmapped(&bookmarks, pages).len();
+        if self.apply_edit(Edit::ImportBookmarks { parent, index, bookmarks, replace: false }) && unmapped > 0 {
+            let n = u64::try_from(unmapped).unwrap_or(u64::MAX);
+            self.notify(crate::i18n::trn(
+                crate::i18n::current(),
+                n,
+                "{n} pasted bookmark points past the last page of this document and has no destination.",
+                "{n} pasted bookmarks point past the last page of this document and have no destination.",
+            ));
+        }
+    }
+}
+
 fn bookmark_at<'a>(items: &'a [pdfcraft_render::OutlineItem], path: &[usize]) -> Option<&'a pdfcraft_render::OutlineItem> {
     let (first, rest) = path.split_first()?;
     let item = items.get(*first)?;

crates/ui-egui/src/editing/save.rs

@@ -1,4 +1,6 @@
 use super::{PdfCraftApp, StagingName, staging_suffixes};
+#[cfg(not(target_arch = "wasm32"))]
+use crate::file_filter::AddFilterAnyCase as _;
 
 /// A save held back by [`Dialog::OverwriteChanged`](crate::Dialog::OverwriteChanged): the file
 /// on disk is another version than the document came from (#2166).
@@ -58,7 +60,7 @@ impl PdfCraftApp {
                 (SaveTarget::InPlace, Some(p), _) if !is_mail_temp_copy(&p) => p,
                 _ => {
                     let name = if name.to_ascii_lowercase().ends_with(".pdf") { name } else { format!("{name}.pdf") };
-                    let dialog = rfd::AsyncFileDialog::new().add_filter("PDF", &["pdf"]).set_file_name(name);
+                    let dialog = rfd::AsyncFileDialog::new().add_filter_any_case("PDF", &["pdf"]).set_file_name(name);
                     let dialog = in_document_folder(dialog, doc_path.as_deref());
                     // The bytes are taken once the user has chosen, so edits made meanwhile are saved too.
                     self.ask_one(crate::pickers::Ask::Save(dialog), None, move |app, dest| {

crates/ui-egui/src/lib.rs

@@ -126,6 +126,7 @@ pub use persist::units;
 #[cfg(not(target_arch = "wasm32"))]
 pub use persist::window_state;
 use platform::drag_pointer;
+use platform::file_filter;
 #[cfg(not(target_arch = "wasm32"))]
 pub use platform::file_watch;
 #[cfg(target_os = "macos")]
@@ -611,6 +612,9 @@ pub struct PdfCraftApp {
     control: Option<control::Control>,
     /// A bookmark being renamed in the Bookmarks panel: (path, text so far).
     pub bookmark_rename: Option<(Vec<usize>, String)>,
+    /// Bookmarks copied or cut in the Bookmarks panel, with their subtrees, ready to paste into
+    /// any document. Destinations are page indices.
+    pub bookmark_clipboard: Option<Vec<pdfcraft_engine::OutlineNode>>,
     /// Number pages dialog settings (1-based pages).
     pub number_draft: NumberDraft,
     pub(crate) word_count_draft: word_count_ui::Draft,

crates/ui-egui/src/panels/bookmarks.rs

@@ -19,6 +19,15 @@ pub enum BmAction {
     Indent(Vec<usize>),
     /// Move it out to follow its parent.
     Outdent(Vec<usize>),
+    /// Copy the bookmark and everything under it to the bookmark clipboard.
+    Copy(Vec<usize>),
+    /// Copy it, then delete it (one undo step: only the delete changes the document).
+    Cut(Vec<usize>),
+    /// Paste the bookmark clipboard under `parent` at `index` (past the end appends).
+    Paste {
+        parent: Vec<usize>,
+        index: usize,
+    },
     /// Bookmarks from the tagged headings, under a new first "Untitled" bookmark.
     FromStructure,
     /// Open New bookmarks from text styles, to choose a style per bookmark level (#1693).
@@ -55,6 +64,8 @@ pub(super) struct OutlineCtx<'a> {
     pub(super) action: &'a mut Option<BmAction>,
     pub(super) rename: &'a mut Option<(Vec<usize>, String)>,
     pub(super) editable: bool,
+    /// The bookmark clipboard holds something to paste.
+    pub(super) can_paste: bool,
     pub(super) current: usize,
     /// Expand all (`Some(usize::MAX)`), collapse all (`Some(0)`) or expand to a depth, this frame.
     pub(super) expand: Option<usize>,
@@ -242,6 +253,11 @@ pub(super) fn outline_item(
                 pick(ui, tl!("Indent"), i > 0, BmAction::Indent(path.to_vec()));
                 pick(ui, tl!("Outdent"), depth > 0, BmAction::Outdent(path.to_vec()));
                 ui.separator();
+                pick(ui, tl!("Cut"), true, BmAction::Cut(path.to_vec()));
+                pick(ui, tl!("Copy"), true, BmAction::Copy(path.to_vec()));
+                let parent = path.get(..depth).unwrap_or_default().to_vec();
+                pick(ui, tl!("Paste"), cx.can_paste, BmAction::Paste { parent, index: i.saturating_add(1) });
+                ui.separator();
                 pick(ui, tl!("Delete"), true, BmAction::Delete(path.to_vec()));
                 if let Some(a) = styled {
                     *cx.action = Some(a);

crates/ui-egui/src/panels/right.rs

@@ -24,6 +24,7 @@ pub fn right_panel(app: &mut PdfCraftApp, ui: &mut egui::Ui) {
     let mut compare_action: Option<crate::compare_ui::PanelAction> = None;
     let mut bm_rename = app.bookmark_rename.clone();
     let bm_editable = app.session.get(id).is_some_and(|d| d.allows_assembly() && d.read_only_reason.is_none());
+    let bm_can_paste = app.bookmark_clipboard.is_some();
     // Prepare a form is open: the Fields panel orders tabs.
     let preparing = app.is_preparing();
     {
@@ -111,6 +112,10 @@ pub fn right_panel(app: &mut PdfCraftApp, ui: &mut egui::Ui) {
                                     bm_action = Some(BmAction::FromTextStyles);
                                     ui.close();
                                 }
+                                if bm_editable && ui.add_enabled(bm_can_paste, egui::Button::new(tl!("Paste bookmarks"))).clicked() {
+                                    bm_action = Some(BmAction::Paste { parent: Vec::new(), index: usize::MAX });
+                                    ui.close();
+                                }
                                 if !info.outline.is_empty() {
                                     for (levels, label) in [
                                         (usize::MAX, tl!("Expand all bookmarks")),
@@ -195,6 +200,7 @@ pub fn right_panel(app: &mut PdfCraftApp, ui: &mut egui::Ui) {
                             action: &mut bm_action,
                             rename: &mut bm_rename,
                             editable: bm_editable,
+                            can_paste: bm_can_paste,
                             current: view.current,
                             expand: bm_expand,
                             matches: &bookmark_matches,

crates/ui-egui/src/platform.rs

@@ -1,4 +1,5 @@
 pub(super) mod drag_pointer;
+pub(super) mod file_filter;
 #[cfg(not(target_arch = "wasm32"))]
 pub mod file_watch;
 #[cfg(target_os = "macos")]

crates/ui-egui/src/platform/file_filter.rs

@@ -0,0 +1,50 @@
+//! Picker filters that list a file whatever the letter case of its extension.
+//!
+//! On Linux and the BSDs, rfd gives each extension to the XDG portal, GTK or Zenity as the glob
+//! `*.<ext>`, and those match it case-sensitively: a "PDF" filter of `pdf` hid `Report.PDF`.
+//! Windows, macOS and the browser already ignore case, so there the extension passes unchanged.
+
+/// Whether the platform's pickers match filter globs case-sensitively.
+const CASE_SENSITIVE_GLOBS: bool = cfg!(all(unix, not(target_os = "macos")));
+
+/// [`rfd::AsyncFileDialog::add_filter`], with each extension matched in any letter case.
+pub(crate) trait AddFilterAnyCase {
+    #[must_use]
+    fn add_filter_any_case(self, name: impl Into<String>, extensions: &[impl AsRef<str>]) -> Self;
+}
+
+impl AddFilterAnyCase for rfd::AsyncFileDialog {
+    fn add_filter_any_case(self, name: impl Into<String>, extensions: &[impl AsRef<str>]) -> Self {
+        let globs: Vec<String> = extensions.iter().map(|e| any_case(e.as_ref(), CASE_SENSITIVE_GLOBS)).collect();
+        self.add_filter(name, &globs)
+    }
+}
+
+/// `ext` as a glob fragment matching any letter case: `pdf` becomes `[pP][dD][fF]`.
+fn any_case(ext: &str, case_sensitive: bool) -> String {
+    if !case_sensitive {
+        return ext.to_owned();
+    }
+    ext.chars()
+        .map(|c| if c.is_ascii_alphabetic() { format!("[{}{}]", c.to_ascii_lowercase(), c.to_ascii_uppercase()) } else { c.to_string() })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::any_case;
+
+    #[test]
+    fn a_case_sensitive_picker_gets_a_glob_matching_every_case() {
+        assert_eq!(any_case("pdf", true), "[pP][dD][fF]");
+        assert_eq!(any_case("PDF", true), "[pP][dD][fF]");
+        assert_eq!(any_case("jp2", true), "[jJ][pP]2");
+        assert_eq!(any_case("*", true), "*");
+    }
+
+    #[test]
+    fn a_case_blind_picker_gets_the_extension_unchanged() {
+        assert_eq!(any_case("pdf", false), "pdf");
+        assert_eq!(any_case("*", false), "*");
+    }
+}

crates/ui-egui/src/tools/camera_ui.rs

@@ -7,6 +7,7 @@ use egui::{Align2, Color32, CornerRadius, Pos2, Rect, Shape, Stroke, vec2};
 use crate::canvas::{DocView, PageXform, ViewAction};
 use crate::page_cursor::Layer;
 use crate::page_pointer::PagePointer;
+use crate::page_router::{Hit, Owner, PagePress};
 use crate::theme::Tokens;
 pub use pdfcraft_engine::camera_clean::Look;
 
@@ -59,8 +60,29 @@ fn screen(xf: &PageXform, c: [f32; 2]) -> Pos2 {
     xf.norm_to_screen(c[0] / xf.pw.max(1e-3), c[1] / xf.ph.max(1e-3))
 }
 
-/// Corner dragging on one page. A press on a page without the quadrilateral moves it there.
-pub(crate) fn page_input(resp: &egui::Response, xf: &PageXform, ptr: &PagePointer, page: usize, view: &mut DocView, allowed: bool) {
+/// The corner of the quadrilateral under `p` on `page`, the nearest within reach: the one hit test
+/// of the camera tool, for the cursor and the press. `None` once the page is enhanced, on a page
+/// without the quadrilateral, or off the page (a press there is no page's), even where a corner at
+/// its edge would reach past it.
+pub(crate) fn hit(xf: &PageXform, page: usize, view: &DocView, p: Pos2) -> Option<Hit> {
+    if view.camera_done.is_some() || !xf.rect.contains(p) {
+        return None;
+    }
+    let q = view.camera.filter(|q| q.page == page)?;
+    let corner = q
+        .corners
+        .iter()
+        .enumerate()
+        .map(|(i, &c)| (i, screen(xf, c).distance(p)))
+        .filter(|(_, d)| *d <= GRAB)
+        .min_by(|a, b| a.1.total_cmp(&b.1))
+        .map(|(i, _)| i)?;
+    Some(Hit::new(Owner::CameraCorner { corner }, Layer::Handle, egui::CursorIcon::Grab))
+}
+
+/// Corner dragging on one page: a corner's own press ([`hit`]) drags it, and a press nobody holds
+/// on a page without the quadrilateral moves it there.
+pub(crate) fn page_input(resp: &egui::Response, xf: &PageXform, ptr: &PagePointer, page: usize, view: &mut DocView, allowed: bool, press: PagePress) {
     let (pointer, origin) = (ptr.pos, ptr.origin);
     if !allowed {
         if pointer.is_some_and(|p| xf.rect.contains(p)) {
@@ -76,23 +98,25 @@ pub(crate) fn page_input(resp: &egui::Response, xf: &PageXform, ptr: &PagePointe
     if view.camera.is_none() && page == view.current {
         view.camera = Some(CameraQuad::inset(page, xf.pw, xf.ph));
     }
-    if resp.drag_started() || resp.clicked() {
-        let pressed = origin.filter(|o| xf.rect.contains(*o));
-        if pressed.is_some() && view.camera.is_none_or(|q| q.page != page) {
-            view.camera = Some(CameraQuad::inset(page, xf.pw, xf.ph));
-        }
-        if resp.drag_started()
-            && let (Some(o), Some(q)) = (pressed, view.camera.as_mut())
-        {
-            q.grab = (0..4)
-                .map(|i| (i, screen(xf, q.corners[i]).distance(o)))
-                .filter(|(_, d)| *d <= GRAB)
-                .min_by(|a, b| a.1.total_cmp(&b.1))
-                .map(|(i, _)| i);
-        }
+    // A press nobody holds on a page without the quadrilateral moves it there: a drag from where it
+    // began, a click where it came up (egui has cleared the press's origin by its release, and the
+    // pointer may have moved on in the same frame).
+    let at = if resp.clicked() { ptr.released } else { origin };
+    if (resp.drag_started() || resp.clicked())
+        && press == PagePress::Free
+        && at.is_some_and(|p| xf.rect.contains(p))
+        && view.camera.is_none_or(|q| q.page != page)
+    {
+        view.camera = Some(CameraQuad::inset(page, xf.pw, xf.ph));
+    }
+    if resp.drag_started()
+        && let PagePress::Mine(Owner::CameraCorner { corner }) = press
+        && let Some(q) = view.camera.as_mut().filter(|q| q.page == page)
+    {
+        q.grab = Some(corner);
     }
     let Some(q) = view.camera.as_mut().filter(|q| q.page == page) else { return };
-    let near = pointer.is_some_and(|p| q.corners.iter().any(|&c| screen(xf, c).distance(p) <= GRAB));
+    // Over a corner, its hit claims the grab cursor.
     if let Some(i) = q.grab {
         view.cursor.claim(Layer::Drag, egui::CursorIcon::Grabbing);
         if let Some(p) = pointer {
@@ -101,11 +125,9 @@ pub(crate) fn page_input(resp: &egui::Response, xf: &PageXform, ptr: &PagePointe
                 *c = [x.clamp(0.0, xf.pw), y.clamp(0.0, xf.ph)];
             }
         }
-        if resp.drag_stopped() {
+        if resp.drag_stopped() || !ptr.primary_down {
             q.grab = None;
         }
-    } else if near {
-        view.cursor.claim(Layer::Handle, egui::CursorIcon::Grab);
     }
 }
 

crates/ui-egui/src/tools/comments.rs

@@ -37,7 +37,7 @@ pub(crate) use geometry::{corner_ratio, page_rotation, resized};
 pub use geometry::{drawn_text_box_rect, text_box_rect};
 #[cfg(test)]
 use input::hover_tip;
-pub(crate) use input::{describe, fill_grabs, hit, keys, nudge_keys, page_after_text, page_input};
+pub(crate) use input::{anchor, context, context_hit, describe, hit, keys, moving_on, nudge_keys, page_after_text, page_input};
 pub use menu::{CanvasAction, fill_picker, recent_custom_colours, remember_custom_colour, status_badge, swatch_grid};
 #[cfg(test)]
 use menu::{RECENT_CUSTOM, same_colour};

crates/ui-egui/src/tools/comments/geometry.rs

@@ -20,10 +20,10 @@ pub(super) fn reshapable(a: &Annotation) -> bool {
         && !a.intent.as_deref().is_some_and(|i| i.ends_with("Dimension"))
 }
 
-/// Whether `tool` picks up a line's end and corner handles: the Select and Fill & Sign tools.
+/// Whether `tool` reaches a line's end and corner handles: the Select and Fill & Sign tools.
 /// The drawing tools draw from where they are pressed, so a new line starts at the end of the
 /// one just drawn rather than dragging it.
-pub(super) fn grabs_points(tool: QuickTool) -> bool {
+pub(super) fn reaches_points(tool: QuickTool) -> bool {
     !matches!(tool, QuickTool::Comment(t) if t.draws() || t.clicks_points())
 }
 

crates/ui-egui/src/tools/comments/input.rs

@@ -1,61 +1,69 @@
 use super::geometry::{
-    CARET_SIZE, HANDLES, clamp_to, corner_ratio, drawn_box, grabs_points, handle_pos, is_markup, point_handle, reshapable, reshaped, resizable,
+    CARET_SIZE, HANDLES, clamp_to, corner_ratio, drawn_box, handle_pos, is_markup, point_handle, reaches_points, reshapable, reshaped, resizable,
     resized, snapped_caret,
 };
 use super::paint::{drawn_shape, edit_anchor, erase, new_comment};
 use super::state::{Composer, ComposerKind, Gesture, PageCx};
 use super::{Annotation, CommentPrefs, CommentTool, DocInfo, DocView, Edit, Pos2, QuickTool, Rect, Shape, vec2};
 use crate::page_cursor::{Layer, Subject};
-use crate::page_router::{CommentPart, Hit, Owner};
+use crate::page_router::{CommentPart, Hit, Owner, PagePress};
 
-/// Comment input on one page, before text selection runs. Returns `true` when the pointer
-/// gesture belongs to commenting (text selection must ignore it).
-pub(crate) fn page_input(ui: &egui::Ui, resp: &egui::Response, cx: &PageCx<'_>, view: &mut DocView) -> bool {
+/// Comment input on one page, before text selection runs. `press` is what this page has to do with
+/// the press the pages hold: a press on a comment where the tool reaches it ([`hit`]: the Select
+/// tool, Fill & Sign over its marks, a shape tool over the selected shape's handles) is that
+/// comment's, and one nobody holds is a commenting tool's. When another tool took this frame
+/// (`taken`: Prepare, added content, which still decide for themselves), the commenting tools leave
+/// it to that tool, as before; the Select tool's click there still unselects. Returns `true` when
+/// the pointer gesture belongs to commenting (text selection must ignore it).
+pub(crate) fn page_input(ui: &egui::Ui, resp: &egui::Response, cx: &PageCx<'_>, press: PagePress, taken: bool, view: &mut DocView) -> bool {
     let (pointer, origin) = (cx.ptr.pos, cx.ptr.origin);
     let page_rect = cx.xf.rect;
-    let pressed_here = origin.is_some_and(|o| page_rect.contains(o));
+    let free = press == PagePress::Free;
+    let pressed_here = free && origin.is_some_and(|o| page_rect.contains(o));
     let over_page = pointer.is_some_and(|p| page_rect.contains(p));
-    let fill_grab = fill_grabs(cx, view);
-    let draw_grab = draw_grabs(cx, view);
+    let owned = match press {
+        PagePress::Mine(Owner::Comment { index, part }) => Some((index, part)),
+        _ => None,
+    };
     let caret_text = if cx.tool == QuickTool::Comment(CommentTool::Caret) { view.page_text(cx.page) } else { None };
     let cv = &mut view.comments;
     if cv.gesture.is_some() && ui.input_mut(|i| i.consume_key(egui::Modifiers::NONE, egui::Key::Escape)) {
         cv.gesture = None;
-        cv.cancelled_drag = true;
         return true;
     }
-    if cv.cancelled_drag {
-        return true;
-    }
-    if resp.secondary_clicked()
-        && let Some(p) = pointer.filter(|p| page_rect.contains(*p))
-    {
-        cv.context_at = Some((cx.page, cx.to_user(p)));
-        cv.selected = cx.hit(p).map(|a| (cx.page, a.index));
-    }
-    let gestures = Gestures { ui, resp, cx, pointer, origin, page_rect, pressed_here, over_page };
+    let moving = moving_on(view, cx.page);
+    let gestures = Gestures { ui, resp, cx, pointer, origin, page_rect, pressed_here, over_page, free };
     match cx.tool {
-        QuickTool::Comment(_) if draw_grab => select_input(ui, resp, cx, view, pointer, origin),
+        // The selected shape's handles, and Fill & Sign's marks, take their own presses.
+        QuickTool::Comment(_) | QuickTool::Fill(_) if owned.is_some() || moving => select_input(ui, resp, cx, view, press, pointer, origin),
+        // Neither a press nor a double-click or a key another tool took this frame.
+        QuickTool::Comment(_) if taken => false,
         QuickTool::Comment(tool) if tool.draws() => gestures.draw_shape(view, tool),
         QuickTool::Comment(tool) if tool.clicks_points() => gestures.click_points(view, tool),
         QuickTool::Comment(CommentTool::Callout) => gestures.callout(view),
         QuickTool::Comment(CommentTool::Attach) => gestures.attach(view),
         QuickTool::Comment(CommentTool::Caret) => gestures.caret(view, caret_text.as_deref()),
         QuickTool::Comment(tool @ (CommentTool::Note | CommentTool::TextBox)) => gestures.note_or_box(view, tool),
-        QuickTool::Select => select_input(ui, resp, cx, view, pointer, origin),
-        QuickTool::Fill(_) if fill_grab => select_input(ui, resp, cx, view, pointer, origin),
+        QuickTool::Select => select_input(ui, resp, cx, view, press, pointer, origin),
         _ => false,
     }
 }
 
+/// A comment (a Fill & Sign mark included) is being moved, resized or reshaped on `page`: it keeps
+/// the page's frames until its gesture ends.
+pub(crate) fn moving_on(view: &DocView, page: usize) -> bool {
+    matches!(view.comments.gesture, Some(Gesture::Move { page: p, .. } | Gesture::Resize { page: p, .. } | Gesture::Reshape { page: p, .. }) if p == page)
+}
+
 /// What of the comments lies under `p`, for the cursor, the tip and the press: the one hit test
 /// of this module. With the Select tool, the selected comment's point handles, then its resize
 /// handles, then the topmost comment. With a Fill & Sign tool, the same over Fill & Sign's marks
 /// only, as Acrobat picks them up: a press anywhere else places the tool's mark. With a shape
 /// tool (rectangle, oval, line, polygon…), only the selected comment's handles, so the shape just
 /// drawn can be resized straight away (#2338); a press anywhere else, the shape itself included,
-/// draws. `None` with other tools, off the page, or with comments hidden.
-pub(crate) fn hit(cx: &PageCx<'_>, view: &DocView, p: Pos2) -> Option<Hit> {
+/// draws. `None` with other tools, off the page, or with comments hidden. `on_link`: a link lies
+/// under `p` ([`crate::link_ui::hit`]).
+pub(crate) fn hit(cx: &PageCx<'_>, view: &DocView, p: Pos2, on_link: bool) -> Option<Hit> {
     if cx.hidden || !cx.xf.rect.contains(p) {
         return None;
     }
@@ -73,7 +81,7 @@ pub(crate) fn hit(cx: &PageCx<'_>, view: &DocView, p: Pos2) -> Option<Hit> {
     };
     let bodies = matches!(cx.tool, QuickTool::Select | QuickTool::Fill(_));
     if let Some(a) = view.comments.selected.filter(|(page, _)| *page == cx.page).and_then(|(_, i)| cx.get(i)).filter(|a| pick(a) && cx.allowed) {
-        if grabs_points(cx.tool)
+        if reaches_points(cx.tool)
             && reshapable(a)
             && let Some(point) = point_handle(cx, a, p)
         {
@@ -91,48 +99,45 @@ pub(crate) fn hit(cx: &PageCx<'_>, view: &DocView, p: Pos2) -> Option<Hit> {
             return Some(Hit::new(Owner::Comment { index: a.index, part: CommentPart::Handle(x, y) }, Layer::Handle, icon));
         }
     }
-    let a = cx.hit(p).filter(|a| bodies && pick(a))?;
+    let a = cx.comment_at(p).filter(|a| bodies && pick(a))?;
     // A click on a highlight over a link follows the link, so the link's hand and tip show there.
-    if cx.tool == QuickTool::Select && a.subtype == "Highlight" && on_link(cx, p) {
+    if cx.tool == QuickTool::Select && a.subtype == "Highlight" && on_link {
         return None;
     }
     let markup = is_markup(&a.subtype);
     let icon = if cx.allowed && !markup { egui::CursorIcon::Move } else { egui::CursorIcon::PointingHand };
-    // What a drag moves whole (a note, a shape, a signature, a Fill & Sign mark) is placed on the
-    // page, over a form field; text markup lies on the text, under one.
-    let layer = if a.fill_sign || !markup { Layer::Placed } else { Layer::Comment };
     // Text markup does not move: a click selects it, a drag across it selects the text.
-    Some(Hit { declines_drag: markup, ..Hit::new(Owner::Comment { index: a.index, part: CommentPart::Body }, layer, icon) })
+    Some(Hit { declines_drag: markup, ..Hit::new(Owner::Comment { index: a.index, part: CommentPart::Body }, layer(a), icon) })
 }
 
-/// Whether the comments take the press on this page (or, with no button down, would take one
-/// under the pointer), so the tools beneath leave it: a live move, resize or reshape, or a press
-/// held by a comment that keeps its drag.
-fn grabs(cx: &PageCx<'_>, view: &DocView) -> bool {
-    if matches!(view.comments.gesture, Some(Gesture::Move { page, .. } | Gesture::Resize { page, .. } | Gesture::Reshape { page, .. }) if page == cx.page)
-    {
-        return true;
+/// The layer a comment's body lies on: what a drag moves whole (a note, a shape, a signature, a
+/// Fill & Sign mark) is placed on the page, over a form field; text markup lies on the text, under
+/// one.
+fn layer(a: &Annotation) -> Layer {
+    if a.fill_sign || !is_markup(&a.subtype) { Layer::Placed } else { Layer::Comment }
+}
+
+/// The comment a right-click at `p` is on: the topmost, with every tool, as a comment's menu shows
+/// whatever tool is active. A highlight over a link is the highlight's here (a left click on it
+/// follows the link, [`hit`]). `None` off the page or with comments hidden.
+pub(crate) fn context_hit(cx: &PageCx<'_>, p: Pos2) -> Option<Hit> {
+    if cx.hidden || !cx.xf.rect.contains(p) {
+        return None;
     }
-    if cx.ptr.any_down {
-        return matches!(view.router.owner(cx.page), Some(Owner::Comment { .. })) && view.router.keeps_drag();
-    }
-    cx.ptr.pos.and_then(|p| hit(cx, view, p)).is_some_and(|h| !h.declines_drag)
+    let a = cx.comment_at(p)?;
+    Some(Hit::new(Owner::Comment { index: a.index, part: CommentPart::Body }, layer(a), egui::CursorIcon::Default))
 }
 
-/// With a Fill & Sign tool, a Fill & Sign mark already on the page is picked up as with the Select
-/// tool ([`hit`]), so the tool does not place a mark there.
-pub(crate) fn fill_grabs(cx: &PageCx<'_>, view: &DocView) -> bool {
-    matches!(cx.tool, QuickTool::Fill(_)) && grabs(cx, view)
+/// A right-click at `p` on this page: the page's menu is anchored there (Delete page, Paste, Copy
+/// Image, a note added here).
+pub(crate) fn anchor(cx: &PageCx<'_>, p: Pos2, view: &mut DocView) {
+    view.comments.context_at = Some((cx.page, cx.to_user(p)));
 }
 
-/// With a shape tool, the selected comment's handles are picked up ([`hit`]).
-fn draw_grabs(cx: &PageCx<'_>, view: &DocView) -> bool {
-    matches!(cx.tool, QuickTool::Comment(_)) && grabs(cx, view)
-}
-
-/// Whether `p` is on one of this page's links.
-fn on_link(cx: &PageCx<'_>, p: Pos2) -> bool {
-    cx.info.links.iter().any(|link| link.page == cx.page && cx.xf.user_rect(cx.info, cx.page, link.rect).contains(p))
+/// A right-click on comment `index` of this page ([`context_hit`], when it wins there) selects it,
+/// and one on anything else selects none.
+pub(crate) fn context(cx: &PageCx<'_>, index: Option<usize>, view: &mut DocView) {
+    view.comments.selected = index.map(|i| (cx.page, i));
 }
 
 /// The tip for the comment under the pointer, with any tool, beside that tool's own cursor: Acrobat
@@ -170,11 +175,21 @@ pub(super) fn hover_tip(a: &Annotation, prefs: &CommentPrefs) -> Option<String>
     Some(if body.is_empty() { who } else { format!("{who}\n{body}") })
 }
 
-/// The Select tool: select, move, resize, edit, delete, on the comment the press was on (its
-/// owner, from [`hit`]). The cursor comes from [`hit`] too.
-fn select_input(ui: &egui::Ui, resp: &egui::Response, cx: &PageCx<'_>, view: &mut DocView, pointer: Option<Pos2>, origin: Option<Pos2>) -> bool {
-    let owner = match view.router.owner(cx.page) {
-        Some(Owner::Comment { index, part }) => cx.get(index).map(|a| (a, part)),
+/// The Select tool: select, move, resize, edit, delete, on the comment the press is on and the
+/// part of it (`press`, from [`hit`]). The cursor comes from [`hit`] too. A click on this page on
+/// anything else (a link, a field, added text, the page) leaves comments unselected; one that
+/// began off the pages is no page's.
+fn select_input(
+    ui: &egui::Ui,
+    resp: &egui::Response,
+    cx: &PageCx<'_>,
+    view: &mut DocView,
+    press: PagePress,
+    pointer: Option<Pos2>,
+    origin: Option<Pos2>,
+) -> bool {
+    let owner = match press {
+        PagePress::Mine(Owner::Comment { index, part }) => cx.get(index).map(|a| (a, part)),
         _ => None,
     };
     let cv = &mut view.comments;
@@ -252,15 +267,16 @@ fn select_input(ui: &egui::Ui, resp: &egui::Response, cx: &PageCx<'_>, view: &mu
     // (egui clears the press origin on release, so clicks are located by the pointer.)
     let on_page = pointer.is_some_and(|p| cx.xf.rect.contains(p));
     if resp.clicked() && on_page {
-        // A click elsewhere (a link beneath text highlighting included: it follows the link)
-        // leaves comments unselected.
+        // A click elsewhere (a link beneath text highlighting included: it follows the link; a
+        // form field; added text) leaves comments unselected.
         match owner {
             Some((a, _)) => {
                 cv.selected = Some((cx.page, a.index));
                 cv.reveal = true;
                 consumed = true;
             }
-            None => cv.selected = None,
+            None if press != PagePress::Elsewhere => cv.selected = None,
+            None => {}
         }
     }
     if resp.double_clicked()
@@ -316,13 +332,21 @@ struct Gestures<'a> {
     pointer: Option<Pos2>,
     origin: Option<Pos2>,
     page_rect: Rect,
+    /// The press began on this page, and nobody holds it: the tool's.
     pressed_here: bool,
     over_page: bool,
+    /// Nobody holds the press, and it began on this page, or no button is down.
+    free: bool,
 }
 
 impl Gestures<'_> {
+    /// The tool's own click: one nobody holds.
+    fn clicked(&self) -> bool {
+        self.free && self.resp.clicked()
+    }
+
     fn draw_shape(&self, view: &mut DocView, tool: CommentTool) -> bool {
-        let Self { ui, resp, cx, pointer, origin, page_rect, pressed_here, over_page } = *self;
+        let Self { ui, resp, cx, pointer, origin, page_rect, pressed_here, over_page, .. } = *self;
         let cv = &mut view.comments;
         if !cx.allowed {
             return false;
@@ -370,7 +394,7 @@ impl Gestures<'_> {
         // it as a one-point ink stroke (a dot). The appearance uses round line caps, so a
         // single PDF point is visible and remains editable like any other drawing.
         if matches!(tool, CommentTool::Ink | CommentTool::FreehandHighlight)
-            && resp.clicked()
+            && self.clicked()
             && over_page
             && let Some(p) = pointer
             && let Some(shape) = drawn_shape(tool, &[cx.to_user(p)])
@@ -402,7 +426,7 @@ impl Gestures<'_> {
             cv.undo_point();
             return true;
         }
-        if resp.clicked()
+        if self.clicked()
             && over_page
             && let Some(p) = pointer
         {
@@ -482,7 +506,7 @@ impl Gestures<'_> {
     }
 
     fn attach(&self, view: &mut DocView) -> bool {
-        let Self { resp, cx, pointer, over_page, .. } = *self;
+        let Self { cx, pointer, over_page, .. } = *self;
         let cv = &mut view.comments;
         if !cx.allowed {
             return false;
@@ -490,7 +514,7 @@ impl Gestures<'_> {
         if over_page {
             view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
         }
-        if resp.clicked()
+        if self.clicked()
             && over_page
             && let Some(p) = pointer
         {
@@ -501,7 +525,7 @@ impl Gestures<'_> {
     }
 
     fn caret(&self, view: &mut DocView, caret_text: Option<&pdfcraft_render::PageText>) -> bool {
-        let Self { resp, cx, pointer, over_page, .. } = *self;
+        let Self { cx, pointer, over_page, .. } = *self;
         let cv = &mut view.comments;
         if !cx.allowed {
             return false;
@@ -509,7 +533,7 @@ impl Gestures<'_> {
         if over_page {
             view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Text);
         }
-        if resp.clicked()
+        if self.clicked()
             && over_page
             && let Some(p) = pointer
         {
@@ -563,7 +587,7 @@ impl Gestures<'_> {
                 }
             }
         }
-        if resp.clicked()
+        if self.clicked()
             && over_page
             && let Some(p) = pointer
         {
@@ -577,9 +601,6 @@ impl Gestures<'_> {
 
 /// Delete / Escape handling for comments (only while no text field has focus).
 pub(crate) fn keys(ctx: &egui::Context, view: &mut DocView, tool: &mut QuickTool, allowed: bool) {
-    if !ctx.input(|i| i.pointer.any_down()) {
-        view.comments.cancelled_drag = false;
-    }
     if ctx.egui_wants_keyboard_input() {
         return;
     }

crates/ui-egui/src/tools/comments/paint.rs

@@ -1,18 +1,30 @@
-use super::geometry::{HANDLES, grabs_points, handle_pos, is_markup, reshapable, reshaped, resizable};
-use super::state::{Gesture, PageCx, SETTLE_SECS};
+use super::geometry::{HANDLES, handle_pos, is_markup, reaches_points, reshapable, reshaped, resizable};
+use super::state::{CommentView, Gesture, PageCx, SETTLE_SECS};
 use super::{
     Annotation, Color32, CommentTool, CornerRadius, DocInfo, DocView, Edit, LineEnding, NewAnnotation, Pos2, QuickTool, Rect, SELECT_BLUE, Shape,
     Stroke, color32, vec2,
 };
+use crate::page_router::{CommentPart, Hit, Owner};
 
-/// Paint comment selection, hover and gesture previews on a page.
-pub(crate) fn paint_page(ui: &egui::Ui, painter: &egui::Painter, cx: &PageCx<'_>, view: &DocView) {
+/// The comment outlined under the pointer: the one a press there would take (`hover`, the top hit),
+/// with the Select tool or, over its own marks, Fill & Sign. Not the selected comment, nor while a
+/// comment is moved, resized or drawn, nor one under a form field or added text that would take
+/// the press.
+pub(super) fn hover_outline<'c>(cx: &'c PageCx<'_>, cv: &CommentView, hover: Option<&Hit>) -> Option<&'c Annotation> {
+    let Some(Owner::Comment { index, part: CommentPart::Body }) = hover.map(|h| h.owner) else { return None };
+    let tool_outlines = matches!(cx.tool, QuickTool::Select | QuickTool::Fill(_));
+    (cv.gesture.is_none() && tool_outlines && cv.selected != Some((cx.page, index))).then(|| cx.get(index)).flatten()
+}
+
+/// Paint comment selection, hover and gesture previews on a page. `hover` is the top hit under the
+/// pointer.
+pub(crate) fn paint_page(ui: &egui::Ui, painter: &egui::Painter, cx: &PageCx<'_>, view: &DocView, hover: Option<&Hit>) {
     let cv = &view.comments;
     let pointer = cx.ptr.pos;
     // A redaction mark shows its fill while the pointer is over it, as Acrobat's does, so the
     // marked area reads before anything is applied.
     if cv.gesture.is_none()
-        && let Some(a) = pointer.and_then(|p| cx.hit(p))
+        && let Some(a) = pointer.and_then(|p| cx.comment_at(p))
         && a.subtype == "Redact"
     {
         let ([r, g, b], opacity) = cx.redact_mark;
@@ -21,11 +33,7 @@ pub(crate) fn paint_page(ui: &egui::Ui, painter: &egui::Painter, cx: &PageCx<'_>
             painter.rect_filled(rect, CornerRadius::ZERO, fill);
         }
     }
-    if cv.gesture.is_none()
-        && let Some(a) = pointer.and_then(|p| cx.hit(p))
-        && (cx.tool == QuickTool::Select || matches!(cx.tool, QuickTool::Fill(_)) && a.fill_sign)
-        && cv.selected != Some((cx.page, a.index))
-    {
+    if let Some(a) = hover_outline(cx, cv, hover) {
         for r in cx.screen_rects(a) {
             painter.rect_stroke(r.expand(2.0), CornerRadius::same(2), Stroke::new(1.0, SELECT_BLUE.gamma_multiply(0.7)), egui::StrokeKind::Outside);
         }
@@ -45,7 +53,7 @@ pub(crate) fn paint_page(ui: &egui::Ui, painter: &egui::Painter, cx: &PageCx<'_>
             return paint_gesture(painter, cx, view);
         }
         let shift = ui.input(|i| i.modifiers.shift);
-        if cx.allowed && grabs_points(cx.tool) && reshapable(a) {
+        if cx.allowed && reaches_points(cx.tool) && reshapable(a) {
             return paint_points(painter, cx, view, a, pointer, shift);
         }
         let r = cx.adjusted_rect(a, cv.gesture.as_ref(), pointer, shift, view.pending_edit.as_ref()).expand(2.0);

crates/ui-egui/src/tools/comments/state.rs

@@ -133,8 +133,6 @@ pub struct CommentView {
     /// Drawings just released: shown from their points until the page raster that includes the
     /// committed annotation arrives, so the stroke never vanishes in between (#1858).
     pub(crate) settling: Vec<Settling>,
-    /// Escape ends egui's drag too; ignore its synthetic release until the mouse is up.
-    pub(super) cancelled_drag: bool,
     pub composer: Option<Composer>,
     /// Reply being typed under the selected card.
     pub reply: String,
@@ -386,7 +384,7 @@ impl PageCx<'_> {
 
     /// The topmost comment under `p`: the one drawn last, in `/Annots` order (inspection lists
     /// comments by position, not in paint order).
-    pub(super) fn hit(&self, p: Pos2) -> Option<&Annotation> {
+    pub(super) fn comment_at(&self, p: Pos2) -> Option<&Annotation> {
         self.comments().filter(|a| self.screen_rects(a).any(|r| r.expand(3.0).contains(p))).max_by_key(|a| a.index)
     }
 

crates/ui-egui/src/tools/comments/tests.rs

@@ -499,3 +499,39 @@ fn text_boxes_fit_their_text() {
     assert_eq!(long[2], 300.0);
     assert!(long[3] - long[1] > 50.0);
 }
+
+/// The hover outline goes round the comment a press under the pointer would take (the top hit
+/// there): not a highlight under a form field, which takes the press.
+#[test]
+fn the_hover_outline_goes_round_what_a_press_would_take() {
+    use super::paint::hover_outline;
+    use crate::page_cursor::Layer;
+    use crate::page_router::{CommentPart, Hit, Owner};
+    let page = PageInfo { width: 200.0, height: 200.0, label: String::new(), crop: [0.0, 0.0, 200.0, 200.0], rotation: 0 };
+    let xf = PageXform { rect: Rect::from_min_size(Pos2::ZERO, vec2(200.0, 200.0)), rot: 0, pw: 200.0, ph: 200.0 };
+    let highlight = Annotation { rect: [50.0, 50.0, 150.0, 150.0], ..annotation("Highlight", None, false) };
+    let info = DocInfo { pages: vec![page], annotations: vec![highlight], ..Default::default() };
+    let prefs = CommentPrefs::default();
+    // The pointer is over the highlight.
+    let ptr = PagePointer { pos: Some(pos2(100.0, 100.0)), ..PagePointer::default() };
+    let cx = PageCx {
+        page: 0,
+        xf: &xf,
+        ptr: &ptr,
+        info: &info,
+        tool: QuickTool::Select,
+        prefs: &prefs,
+        allowed: true,
+        hidden: false,
+        redact_mark: ([0.0; 3], 1.0),
+    };
+    let on = |owner, layer| Hit::new(owner, layer, egui::CursorIcon::PointingHand);
+    let comment = on(Owner::Comment { index: 0, part: CommentPart::Body }, Layer::Comment);
+    let field = on(Owner::Field { field: 0, widget: 0 }, Layer::Field);
+    let cv = CommentView::default();
+    assert!(hover_outline(&cx, &cv, Some(&comment)).is_some(), "the highlight a press there selects");
+    assert!(hover_outline(&cx, &cv, Some(&field)).is_none(), "not under a field that takes the press");
+    assert!(hover_outline(&cx, &cv, None).is_none(), "nor where nothing would take it");
+    let selected = CommentView { selected: Some((0, 0)), ..CommentView::default() };
+    assert!(hover_outline(&cx, &selected, Some(&comment)).is_none(), "the selected comment has its own frame");
+}

crates/ui-egui/src/tools/content_ui.rs

@@ -3,6 +3,8 @@
 //! (images keep their proportions), double-click text to retype it, format it from the panel,
 //! Delete to remove it. Each change is one undoable engine edit.
 
+#[cfg(not(target_arch = "wasm32"))]
+use crate::file_filter::AddFilterAnyCase as _;
 use egui::{Color32, CornerRadius, Pos2, Rect, Stroke};
 use pdfcraft_engine::{Added, AddedContent, AddedText, Edit};
 use pdfcraft_render::DocInfo;
@@ -897,7 +899,7 @@ impl crate::PdfCraftApp {
             Some(_) => {}
             None => {
                 let dialog = rfd::AsyncFileDialog::new()
-                    .add_filter(tl!("Images"), &["png", "jpg", "jpeg", "tif", "tiff", "gif", "bmp", "jp2", "j2k", "jpx"])
+                    .add_filter_any_case(tl!("Images"), &["png", "jpg", "jpeg", "tif", "tiff", "gif", "bmp", "jp2", "j2k", "jpx"])
                     .set_title(title);
                 let target = self.active_ids().map(|(_, id)| id);
                 self.ask_one(crate::pickers::Ask::File(dialog), target, read);

crates/ui-egui/src/tools/edit_text_ui.rs

@@ -23,7 +23,7 @@ mod layout;
 pub(crate) use background::TextBackground;
 pub use image::{CropMode, DragTarget, ImageAction, ImageDrag, ImageHandle, ImageSelection, image_menu_id};
 pub(crate) use image::{
-    ImageCx, Matrix, body_hit as picture_hit, crop_controls_contain, handle_hit as picture_handle_hit, image_context_menu, image_input,
+    ImageCx, Matrix, body_hit as picture_hit, crop_controls_contain, crop_hit, handle_hit as picture_handle_hit, image_context_menu, image_input,
     quad_contains, user_to_screen,
 };
 #[cfg(test)]

crates/ui-egui/src/tools/edit_text_ui/image.rs

@@ -541,6 +541,14 @@ pub(crate) fn handle_hit(
     Some(Hit::new(picture(PicturePart::Corner(grip)), Layer::Handle, obb.handle_cursor(handle)))
 }
 
+/// The picture being cropped on `page`: crop mode owns every press there, the controls beside its
+/// frame included, so the paragraphs under it and the empty page's marquee never take a crop
+/// button's press before the picture does. `None` when no picture on `page` is being cropped.
+pub(crate) fn crop_hit(view: &DocView, page: usize) -> Option<Hit> {
+    let selection = view.image_selection.as_ref().filter(|s| s.page == page && s.crop.is_some())?;
+    Some(Hit::new(Owner::Picture { index: selection.index, part: PicturePart::Body }, Layer::Handle, egui::CursorIcon::Default))
+}
+
 /// The picture under `p` (its shape, not only its box): a click selects it, a drag moves the
 /// selected one. On the text layer, asked before the paragraphs: editable text on top of a
 /// picture takes the press.

crates/ui-egui/src/tools/fill_sign.rs

@@ -3,6 +3,7 @@
 //! signature. Everything is an annotation (typewriter text, PdfCraft-drawn stamps, ink), so it
 //! can be moved, deleted and undone like any comment.
 
+use crate::file_filter::AddFilterAnyCase as _;
 use egui::{Color32, CornerRadius, Pos2, Sense, Stroke, pos2, vec2};
 use pdfcraft_engine::signature_scan::{DEFAULT_SENSITIVITY, PREVIEW_MAX_SIDE, SCAN_MAX_SIDE, ScanError};
 use pdfcraft_engine::{Edit, FillMark, NewAnnotation, PhotoRect, Shape, SignatureImage, SignaturePhoto, Style, Turn};
@@ -455,7 +456,7 @@ pub(crate) struct PageInput<'a> {
 }
 
 /// Preview and clicks with a Fill & Sign tool on one page.
-pub(crate) fn page_input(cx: PageToolContext<'_>, input: PageInput<'_>, view: &mut DocView) -> Option<FillAction> {
+pub(crate) fn page_input(cx: PageToolContext<'_>, input: PageInput<'_>, free: bool, view: &mut DocView) -> Option<FillAction> {
     let PageToolContext { ui, resp, xf, ptr, page, info, .. } = cx;
     let PageInput { tool, text_size, text_color, signature, initials, preview, author, date_text } = input;
     let pointer = ptr.within(xf.rect)?;
@@ -475,7 +476,8 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, input: PageInput<'_>, view: &m
     } else {
         view.cursor.claim(Layer::ToolArea, if tool == FillTool::Text { egui::CursorIcon::Text } else { egui::CursorIcon::Crosshair });
     }
-    if !resp.clicked() {
+    // The tool's own click: one nobody holds.
+    if !(free && resp.clicked()) {
         return None;
     }
     // Typed text starts a little above the click, as displayed.
@@ -786,7 +788,7 @@ impl crate::PdfCraftApp {
         let epoch = self.dialog_epoch();
         let initials = self.signature_draft.initials;
         let scan = self.signature_draft.scan_mode;
-        let dialog = rfd::AsyncFileDialog::new().add_filter(tl!(if scan { "Photo" } else { "Image" }), &["png", "jpg", "jpeg"]);
+        let dialog = rfd::AsyncFileDialog::new().add_filter_any_case(tl!(if scan { "Photo" } else { "Image" }), &["png", "jpg", "jpeg"]);
         #[cfg(not(target_arch = "wasm32"))]
         self.ask_one(crate::pickers::Ask::File(dialog), None, move |app, path| {
             if app.dialog_epoch() != epoch

crates/ui-egui/src/tools/forms_ui.rs

@@ -15,7 +15,7 @@ use pdfcraft_render::DocInfo;
 
 use crate::canvas::{DocView, PageToolContext, PageXform};
 use crate::page_cursor::Layer;
-use crate::page_router::{Hit, Owner};
+use crate::page_router::{Hit, Owner, PagePress};
 use crate::theme::Tokens;
 
 const FOCUS_BLUE: Color32 = Color32::from_rgb(0x14, 0x73, 0xE6);
@@ -182,19 +182,30 @@ pub(crate) fn hit(xf: &PageXform, info: &DocInfo, page: usize, form: &[FormField
     Some(Hit::new(Owner::Field { field, widget }, Layer::Field, icon))
 }
 
-/// Presses and clicks on form widgets of one page, on the field the press was on ([`hit`]).
-/// `true` while a field holds the press.
-pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], allowed: bool, view: &mut DocView) -> bool {
-    let PageToolContext { ui, resp, xf, ptr, page, info, .. } = cx;
-    // The field's tooltip (`/TU`) under the pointer, as Acrobat shows it on hover (#3854). ISO
-    // 32000-2 Table 226 makes it the name the user interface identifies the field by.
-    if let Some(p) = ptr.within(xf.rect)
-        && let Some(Owner::Field { field, .. }) = hit(xf, info, page, form, allowed, p).map(|h| h.owner)
+/// The tooltip (`/TU`) of the field under the pointer, as Acrobat shows it on hover (#3854): only
+/// where the field is what a press would take (`hover`, the top hit there). ISO 32000-2 Table 226
+/// makes it the name the user interface identifies the field by.
+pub(crate) fn tooltip(resp: &egui::Response, form: &[FormField], hover: Option<&Hit>) {
+    if let Some(Owner::Field { field, .. }) = hover.map(|h| h.owner)
         && let Some(tip) = form.get(field).and_then(|f| f.tooltip.as_deref()).filter(|t| !t.trim().is_empty())
     {
         resp.clone().on_hover_text_at_pointer(tip);
     }
-    let Some(Owner::Field { field, widget: wi }) = view.router.owner(page) else { return false };
+}
+
+/// Presses and clicks on form widgets of one page, on the field the press is on (`press`, from
+/// [`hit`]). `released_over`: the press's click came up over the widget it began on. `true` while a
+/// field holds the press.
+pub(crate) fn page_input(
+    cx: PageToolContext<'_>,
+    form: &[FormField],
+    allowed: bool,
+    press: PagePress,
+    released_over: bool,
+    view: &mut DocView,
+) -> bool {
+    let PageToolContext { ui, resp, xf, ptr, page, info, .. } = cx;
+    let PagePress::Mine(Owner::Field { field, widget: wi }) = press else { return false };
     let Some((f, w)) = form.get(field).and_then(|f| f.widgets.get(wi).map(|w| (f, w))) else { return false };
     let usable = usable(f, w, allowed);
     // A text field opens on the press rather than the click, so a drag that starts on it
@@ -210,8 +221,7 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], allowed: b
     }
     // A click counts released over the widget its press was on, as a button's does: one that slips
     // off it first does nothing (a check box's overlay closes on it too).
-    if !resp.clicked() || !ptr.pos.and_then(|p| hit(xf, info, page, form, allowed, p)).is_some_and(|h| h.owner == Owner::Field { field, widget: wi })
-    {
+    if !resp.clicked() || !released_over {
         return true;
     }
     if !allowed {
@@ -489,7 +499,8 @@ fn calendar(ctx: &egui::Context, view: &mut DocView, field: egui::Rect, fmt: &st
     picked
 }
 
-/// Paint focus and hover frames on a page, the pages' `pointer` over it.
+/// Paint focus and hover frames on a page: the hover frame round the widget a press under the
+/// pointer would take (`hover`, the top hit there).
 pub(crate) fn paint_page(
     painter: &egui::Painter,
     xf: &PageXform,
@@ -497,9 +508,13 @@ pub(crate) fn paint_page(
     info: &DocInfo,
     form: &[FormField],
     view: &DocView,
-    pointer: Option<Pos2>,
+    hover: Option<&Hit>,
 ) {
-    for f in form {
+    let hovered = match hover.map(|h| h.owner) {
+        Some(Owner::Field { field, widget }) => Some((field, widget)),
+        _ => None,
+    };
+    for (fi, f) in form.iter().enumerate() {
         for (wi, w) in f.widgets.iter().enumerate().filter(|(_, w)| w.page == Some(page) && !w.hidden) {
             let r = widget_rect(xf, info, page, w.rect);
             let focused = view.forms.focus.as_ref().is_some_and(|x| x.name == f.name && x.widget == wi);
@@ -508,7 +523,7 @@ pub(crate) fn paint_page(
             }
             if view.forms.unbaked.contains(&(f.name.clone(), page)) {
                 paint_unbaked_widget(painter, xf, f, w, r);
-            } else if fillable(f) && pointer.is_some_and(|p| r.contains(p)) {
+            } else if fillable(f) && hovered == Some((fi, wi)) {
                 painter.rect_stroke(r, CornerRadius::same(1), Stroke::new(1.0, FOCUS_BLUE.gamma_multiply(0.8)), egui::StrokeKind::Outside);
             }
         }

crates/ui-egui/src/tools/link_ui.rs

@@ -4,14 +4,17 @@
 
 use egui::{Color32, CornerRadius, Pos2, Rect, Stroke};
 use pdfcraft_engine::{Edit, LinkAction, LinkHighlight, LinkItem, LinkStyle};
-use pdfcraft_render::DocInfo;
+use pdfcraft_render::{DocInfo, LinkTarget};
 
 use crate::canvas::{DocView, PageToolContext, PageXform};
 use crate::page_cursor::Layer;
+use crate::page_router::{Hit, Owner};
 use crate::theme::{self, Tokens};
-use crate::{PdfCraftApp, widgets};
+use crate::{PdfCraftApp, QuickTool, widgets};
 
 const LINK_BLUE: Color32 = Color32::from_rgb(0x14, 0x73, 0xE6);
+/// How far around a link (screen points) the Link tool finds it, so a thin one can be picked.
+const LINK_TOOL_MARGIN: f32 = 2.0;
 
 #[derive(Clone, Debug, Default, PartialEq)]
 pub struct LinkView {
@@ -46,7 +49,7 @@ pub struct LinkDraft {
     pub style: LinkStyle,
 }
 
-pub(crate) fn screen_rect(xf: &PageXform, info: &DocInfo, page: usize, r: [f64; 4]) -> Rect {
+fn screen_rect(xf: &PageXform, info: &DocInfo, page: usize, r: [f64; 4]) -> Rect {
     xf.user_rect(info, page, [r[0] as f32, r[1] as f32, r[2] as f32, r[3] as f32])
 }
 
@@ -56,8 +59,44 @@ fn to_user(xf: &PageXform, info: &DocInfo, page: usize, p: Pos2) -> [f64; 2] {
     [u[0] as f64, u[1] as f64]
 }
 
-/// Link tool input on one page. Returns `true` when the gesture belongs to the tool.
-pub(crate) fn page_input(cx: PageToolContext<'_>, links: &[LinkItem], view: &mut DocView) -> bool {
+/// The link under `p` on `page`: the one hit test of links, for the hand, the tip and the press.
+/// Of stacked links, the topmost (the last in `/Annots`, drawn on top). Only the Select tool
+/// follows links and the Link tool edits them (`Layer::reached_by`). The Link tool finds every link
+/// the document has (`links`, the engine's), with a margin around each so a thin one can be
+/// picked, and a drag from one draws a new link. The other tools find the links the renderer can
+/// follow, which have a target (`info.links`). The tip is the link's target.
+pub(crate) fn hit(xf: &PageXform, info: &DocInfo, page: usize, links: &[LinkItem], tool: QuickTool, p: Pos2) -> Option<Hit> {
+    // A press off the page is no page's, so nothing there is a link's, the margin included.
+    if !xf.rect.contains(p) {
+        return None;
+    }
+    let (index, link) = if tool == QuickTool::Link {
+        let index = links.iter().rfind(|l| l.page == page && screen_rect(xf, info, page, l.rect).expand(LINK_TOOL_MARGIN).contains(p))?.index;
+        (index, info.links.iter().find(|l| l.page == page && l.index == index))
+    } else {
+        let link = info.links.iter().rfind(|l| l.page == page && xf.user_rect(info, page, l.rect).contains(p))?;
+        (link.index, Some(link))
+    };
+    let tip = link.map(|l| target_label(info, &l.target));
+    let declines_drag = tool == QuickTool::Link;
+    Some(Hit { tip, declines_drag, ..Hit::new(Owner::Link { index }, Layer::Link, egui::CursorIcon::PointingHand) })
+}
+
+/// What a link's tip says it goes to.
+fn target_label(info: &DocInfo, target: &LinkTarget) -> String {
+    match target {
+        LinkTarget::Page(n, _) => crate::i18n::fmt(tl!("Go to page {p}"), &[("p", info.pages.get(*n).map(|p| p.label.as_str()).unwrap_or("?"))]),
+        LinkTarget::Uri(u) => u.clone(),
+        LinkTarget::SetLayers { .. } => tl!("Set layer visibility").to_string(),
+        LinkTarget::RemoteGoTo { file, .. } => file.clone(),
+        LinkTarget::Other(s) => crate::i18n::fmt(tl!("{s} action"), &[("s", s)]),
+    }
+}
+
+/// Link tool input on one page: `free` when nobody holds the press and it began on this page,
+/// `owner` the link that holds it (by its `/Annots` index), and `context` the link a right-click is
+/// on. A drag from either draws a new link. Returns `true` when the gesture belongs to the tool.
+pub(crate) fn page_input(cx: PageToolContext<'_>, free: bool, owner: Option<usize>, context: Option<usize>, view: &mut DocView) -> bool {
     let PageToolContext { ui, resp, xf, ptr, page, info, .. } = cx;
     let pointer = ptr.pos;
     let lv = &mut view.links;
@@ -75,36 +114,39 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, links: &[LinkItem], view: &mut
         }
         return true;
     }
-    let Some(p) = pointer.filter(|p| xf.rect.contains(*p)) else { return false };
-    let hit = links.iter().filter(|l| l.page == page).find(|l| screen_rect(xf, info, page, l.rect).expand(2.0).contains(p));
-    match hit {
-        Some(_) => view.cursor.claim(Layer::Link, egui::CursorIcon::PointingHand),
-        None => view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair),
-    }
-    if resp.secondary_clicked()
-        && let Some(l) = hit
+    // A drag that nobody holds, or from a link (whose hit lets the drag go), draws a new link from
+    // where its press began on this page. egui may see the drag only once the pointer is past the
+    // page's edge.
+    if resp.drag_started()
+        && (free || owner.is_some())
+        && let Some(origin) = ptr.origin.filter(|o| xf.rect.contains(*o))
     {
-        lv.selected = Some((page, l.index));
-        lv.context = Some((page, l.index));
+        lv.drag = Some((page, origin));
         return true;
     }
-    if resp.clicked() || resp.double_clicked() {
+    if !pointer.is_some_and(|p| xf.rect.contains(p)) {
+        return false;
+    }
+    // Over a link, its hit claims the hand.
+    view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
+    if let Some(index) = context {
+        lv.selected = Some((page, index));
+        lv.context = Some((page, index));
+        return true;
+    }
+    // The tool's own click: on a link, or one nobody holds.
+    if (resp.clicked() || resp.double_clicked()) && (free || owner.is_some()) {
         let now = ui.input(|i| i.time);
         // A second click on the same link soon after the first is a double-click.
-        let double = resp.double_clicked() || hit.is_some_and(|l| lv.last_click.is_some_and(|(t, p, k)| p == page && k == l.index && now - t < 0.5));
-        lv.last_click = hit.map(|l| (now, page, l.index));
-        lv.selected = hit.map(|l| (page, l.index));
-        if double && let Some(l) = hit {
-            lv.open_existing = Some((page, l.index));
+        let double = resp.double_clicked() || owner.is_some_and(|k| lv.last_click.is_some_and(|(t, p, l)| p == page && l == k && now - t < 0.5));
+        lv.last_click = owner.map(|k| (now, page, k));
+        lv.selected = owner.map(|k| (page, k));
+        if double && let Some(k) = owner {
+            lv.open_existing = Some((page, k));
             lv.last_click = None;
         }
         return true;
     }
-    if resp.drag_started() {
-        let origin = ptr.origin.unwrap_or(p);
-        lv.drag = Some((page, origin));
-        return true;
-    }
     resp.is_pointer_button_down_on()
 }
 

crates/ui-egui/src/tools/measure_ui.rs

@@ -1,4 +1,6 @@
 //! Measure objects: page-space clicks, live readings and persistent drawing scales.
+#[cfg(not(target_arch = "wasm32"))]
+use crate::file_filter::AddFilterAnyCase as _;
 use crate::{LeftPanel, PdfCraftApp, QuickTool, canvas::DocView, page_cursor::Layer, theme::Tokens, widgets};
 use egui::{Color32, Pos2, Stroke};
 use pdfcraft_engine::{
@@ -202,9 +204,23 @@ fn snap_to_content(
     None
 }
 
+/// The Measure tools' own clicks this frame: those of a press nobody holds.
+#[derive(Clone, Copy)]
+pub(crate) struct Clicks {
+    pub single: bool,
+    pub double: bool,
+}
+
+impl Clicks {
+    /// `resp`'s clicks, when the press is the tool's (`free`).
+    pub(crate) fn of(resp: &egui::Response, free: bool) -> Self {
+        Clicks { single: free && resp.clicked(), double: free && resp.double_clicked() }
+    }
+}
+
 pub(crate) fn page_input(
     ui: &egui::Ui,
-    resp: &egui::Response,
+    clicks: Clicks,
     doc: &Document,
     view: &mut DocView,
     cx: &crate::comments::PageCx<'_>,
@@ -254,7 +270,7 @@ pub(crate) fn page_input(
             point = measure::snap::constrain(*last, point);
         }
         hover = Some(point);
-        if resp.clicked() {
+        if clicks.single {
             if state.page != Some(page) {
                 state.cancel();
                 state.page = Some(page);
@@ -284,7 +300,7 @@ pub(crate) fn page_input(
         }
     }
     if state.page == Some(page) && !state.points.is_empty() {
-        if (resp.double_clicked() || !typing && ui.input(|i| i.key_pressed(egui::Key::Enter))) && matches!(tool, Tool::Perimeter | Tool::Area) {
+        if (clicks.double || !typing && ui.input(|i| i.key_pressed(egui::Key::Enter))) && matches!(tool, Tool::Perimeter | Tool::Area) {
             finish(state, &mut view.pending_edit, doc, page, tool, author, units);
         }
         if !typing && ui.input(|i| i.key_pressed(egui::Key::Backspace)) {
@@ -613,7 +629,7 @@ fn export_csv(app: &mut PdfCraftApp) {
                 match app.export_dir_override.as_ref().map(|d| std::path::PathBuf::from(d).join("measurements.csv")) {
                     Some(path) => write(app, path),
                     None => {
-                        let dialog = rfd::AsyncFileDialog::new().set_file_name("measurements.csv").add_filter("CSV", &["csv"]);
+                        let dialog = rfd::AsyncFileDialog::new().set_file_name("measurements.csv").add_filter_any_case("CSV", &["csv"]);
                         app.ask_one(crate::pickers::Ask::Save(dialog), None, write);
                     }
                 }

crates/ui-egui/src/tools/prepare.rs

@@ -13,7 +13,7 @@ use pdfcraft_render::DocInfo;
 use crate::canvas::{DocView, PageToolContext, PageXform};
 use crate::comments;
 use crate::page_cursor::Layer;
-use crate::page_router::{Hit, Owner};
+use crate::page_router::{Hit, Owner, PagePress};
 use crate::theme;
 use crate::widgets;
 
@@ -285,8 +285,17 @@ pub(crate) fn hit(
     Some(Hit::new(Owner::PrepareField { field, widget }, Layer::Placed, egui::CursorIcon::Move))
 }
 
-/// Pointer input on one page while preparing a form.
-pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], tool: Option<FieldTool>, allowed: bool, view: &mut DocView) -> Outcome {
+/// Pointer input on one page while preparing a form: `press` says whether the press is a field's
+/// or a corner's ([`hit`]), nobody's (a field tool draws, the Select tool draws a selection
+/// rectangle), or another page's.
+pub(crate) fn page_input(
+    cx: PageToolContext<'_>,
+    form: &[FormField],
+    tool: Option<FieldTool>,
+    allowed: bool,
+    press: PagePress,
+    view: &mut DocView,
+) -> Outcome {
     let PageToolContext { ui, resp, xf, ptr, page, info, .. } = cx;
     let mut out = Outcome { consumed: false, properties: false, placed: false, table: None };
     let pointer = ptr.pos;
@@ -369,71 +378,30 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], tool: Opti
         return out;
     }
 
-    let Some(p) = pointer.filter(|p| xf.rect.contains(*p)) else { return out };
-    if !allowed {
-        return out;
-    }
-    if let Some(tool) = tool {
-        view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
-        if resp.drag_started() || resp.clicked() {
-            let origin = ptr.origin.filter(|o| xf.rect.contains(*o)).unwrap_or(p);
-            prep.grab = Some((page, Grab::Draw(origin), origin));
-            out.consumed = true;
-            if resp.clicked() {
-                // A click without a drag: finish at once.
-                prep.grab = None;
-                if tool == FieldTool::TextTable {
-                    out.table = Some((page, table_rect(xf, Rect::from_min_size(p, egui::Vec2::ZERO))));
-                    out.placed = true;
-                    return out;
-                }
-                let at = to_user(xf, info, page, p);
-                let (w, h) = tool.default_size();
-                let join = prep.selected.as_ref().and_then(|(n, _)| form.iter().find(|f| &f.name == n));
-                prep.select_added = Some(form.len());
-                view.pending_edit = Some(Edit::AddField { page, rect: [at[0], at[1] - h, at[0] + w, at[1]], kind: tool.new_field(join), name: None });
-                out.placed = true;
-            }
-        }
-        return out;
-    }
-
-    // Right-click a field: select it (the context menu acts on it).
-    if resp.secondary_clicked()
-        && let Some((f, wi)) = form.iter().find_map(|f| {
-            f.widgets.iter().enumerate().find(|(_, w)| w.page == Some(page) && screen_rect(xf, info, page, w.rect).contains(p)).map(|(i, _)| (f, i))
-        })
-    {
-        let key = (f.name.clone(), wi);
-        if let Some(i) = prep.also.iter().position(|k| *k == key) {
-            // Part of the selection: it becomes the anchor the others line up with.
-            prep.also.remove(i);
-            if let Some(old) = prep.selected.replace(key) {
-                prep.also.push(old);
-            }
-        } else if prep.selected.as_ref() != Some(&key) {
-            prep.selected = Some(key);
-            prep.also.clear();
-        }
-    }
-    // The Select tool: what the press was on ([`hit`]), a corner handle or a field; elsewhere a
-    // drag draws a selection rectangle. A press held by something drawn over the fields (a
-    // comment) is not Prepare's.
-    let owner = view.router.owner(page);
-    let held = matches!(owner, Some(Owner::PrepareField { .. } | Owner::PrepareCorner { .. }));
-    let hit = match owner {
-        Some(Owner::PrepareField { field, widget }) => form.get(field).map(|f| (f, widget)),
+    // The Select tool: what the press is on ([`hit`]), a corner handle or a field; a press nobody
+    // holds draws a selection rectangle, or a field with a field tool. A press held by something
+    // drawn over the fields (a comment) is not Prepare's.
+    let free = press == PagePress::Free;
+    let held = matches!(press, PagePress::Mine(Owner::PrepareField { .. } | Owner::PrepareCorner { .. }));
+    let hit = match press {
+        PagePress::Mine(Owner::PrepareField { field, widget }) => form.get(field).map(|f| (f, widget)),
         _ => None,
     };
-    if resp.drag_started() && (held || owner.is_none()) {
-        let origin = ptr.origin.unwrap_or(p);
-        if let Some(Owner::PrepareCorner { left, top }) = owner {
+    // A drag starts from where its press began on this page: egui may see it only once the pointer
+    // is past the page's edge.
+    if allowed
+        && resp.drag_started()
+        && (held || free)
+        && let Some(origin) = ptr.origin.filter(|o| xf.rect.contains(*o))
+    {
+        out.consumed = true;
+        if tool.is_some() {
+            prep.grab = Some((page, Grab::Draw(origin), origin));
+        } else if let PagePress::Mine(Owner::PrepareCorner { left, top }) = press {
             prep.grab = Some((page, Grab::Corner(left, top), origin));
-            out.consumed = true;
         } else if let Some((f, wi)) = hit {
             prep.selected = Some((f.name.clone(), wi));
             prep.grab = Some((page, Grab::Move, origin));
-            out.consumed = true;
         } else {
             prep.marquee_before = Some(prep.selected.iter().chain(prep.also.iter()).cloned().collect());
             if !ui.input(|i| i.modifiers.shift || i.modifiers.command) {
@@ -441,7 +409,29 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], tool: Opti
                 prep.also.clear();
             }
             prep.grab = Some((page, Grab::Select(origin), origin));
+        }
+        return out;
+    }
+    let Some(p) = pointer.filter(|p| xf.rect.contains(*p)) else { return out };
+    if !allowed {
+        return out;
+    }
+    if let Some(tool) = tool {
+        view.cursor.claim(Layer::ToolArea, egui::CursorIcon::Crosshair);
+        // A click without a drag places the field at once.
+        if free && resp.clicked() {
             out.consumed = true;
+            if tool == FieldTool::TextTable {
+                out.table = Some((page, table_rect(xf, Rect::from_min_size(p, egui::Vec2::ZERO))));
+                out.placed = true;
+                return out;
+            }
+            let at = to_user(xf, info, page, p);
+            let (w, h) = tool.default_size();
+            let join = prep.selected.as_ref().and_then(|(n, _)| form.iter().find(|f| &f.name == n));
+            prep.select_added = Some(form.len());
+            view.pending_edit = Some(Edit::AddField { page, rect: [at[0], at[1] - h, at[0] + w, at[1]], kind: tool.new_field(join), name: None });
+            out.placed = true;
         }
         return out;
     }
@@ -450,7 +440,7 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], tool: Opti
         out.properties = true;
         return out;
     }
-    if resp.clicked() && (held || owner.is_none()) {
+    if resp.clicked() && (held || free) {
         let extend = ui.input(|i| i.modifiers.shift || i.modifiers.command);
         match hit {
             // Shift/⌘-click adds or removes a field from the selection.
@@ -469,6 +459,28 @@ pub(crate) fn page_input(cx: PageToolContext<'_>, form: &[FormField], tool: Opti
     out
 }
 
+/// A right-click on widget `widget` of field `field` (the top hit there, [`hit`]): the field is
+/// selected, so the menu acts on it. Part of a selection of several, it becomes the anchor the
+/// others line up with. Not while a field is dragged or a rectangle drawn: the release acts on
+/// the selection the drag began with.
+pub(crate) fn context(form: &[FormField], field: usize, widget: usize, view: &mut DocView) {
+    let Some(f) = form.get(field) else { return };
+    let key = (f.name.clone(), widget);
+    let prep = &mut view.prepare;
+    if prep.grab.is_some() || prep.ignore_release {
+        return;
+    }
+    if let Some(i) = prep.also.iter().position(|k| *k == key) {
+        prep.also.remove(i);
+        if let Some(old) = prep.selected.replace(key) {
+            prep.also.push(old);
+        }
+    } else if prep.selected.as_ref() != Some(&key) {
+        prep.selected = Some(key);
+        prep.also.clear();
+    }
+}
+
 /// Align, Center, Distribute and Set Fields to Same Size (Prepare a form, several fields
 /// selected).
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]