Choose the amiibo folder with the host's folder dialog

The Amiibo tab's folder field took no typing: the menu never passes typed characters to Dear ImGui, so "Open" only
re-read "./amiibo". A missing folder said so at the bottom of the right pane, below its scroll.

"Open" now shows the shell's folder dialog on Windows (IFileOpenDialog on a thread of its own, owned by the game
window) and SDL_ShowOpenFolderDialog on the SDL window thread elsewhere; the tab shows the folder as text and names a
missing one inside the empty list.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

runtime/folder_pick.h

@@ -0,0 +1,18 @@
+// The host's own folder dialog, for menu pages that point at a folder (the Amiibo tab): folder_pick_win.cpp with Win32,
+// folder_pick_sdl.c with SDL. The menu has no text entry, so a folder is chosen here or by walking the page's list.
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// done gets the chosen folder (UTF-8) or NULL when the player cancelled or the host has no dialog.
+typedef void (*FolderPickDone)(const char *path, void *ctx);
+
+// Opens the dialog at start (may be relative or missing) and returns at once; done runs later on another thread, once.
+// The caller keeps one dialog open at a time.
+void folder_pick(const char *start, FolderPickDone done, void *ctx);
+
+#ifdef __cplusplus
+}
+#endif

runtime/folder_pick_sdl.c

@@ -0,0 +1,42 @@
+// The SDL front end of folder_pick.h: SDL_ShowOpenFolderDialog (the desktop portal, else zenity), started on the window
+// thread, which runs SDL's event loop that delivers the portal's answer.
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <SDL3/SDL.h>
+
+#include "folder_pick.h"
+#include "host.h"
+#include "input_sdl.h"
+
+typedef struct {
+    char start[PATH_MAX];                // absolute, or empty: the dialog's own default
+    FolderPickDone done;
+    void *ctx;
+} PickReq;
+
+static void SDLCALL on_pick(void *userdata, const char *const *list, int filter) {
+    (void)filter;
+    PickReq *r = userdata;
+    if (!list) rt_log("folder_pick: the folder dialog failed (%s)", SDL_GetError());
+    r->done(list && list[0] ? list[0] : NULL, r->ctx);
+    free(r);
+}
+
+static void show(void *arg) {
+    PickReq *r = arg;
+    SDL_ShowOpenFolderDialog(on_pick, r, gfx_window_sdl(), r->start[0] ? r->start : NULL, false);
+}
+
+void folder_pick(const char *start, FolderPickDone done, void *ctx) {
+    PickReq *r = calloc(1, sizeof *r);
+    if (!r) {
+        done(NULL, ctx);
+        return;
+    }
+    r->done = done;
+    r->ctx = ctx;
+    if (start && *start && !realpath(start, r->start)) r->start[0] = 0;
+    gfx_window_sdl_run(show, r);
+}

runtime/folder_pick_win.cpp

@@ -0,0 +1,84 @@
+// The Win32 front end of folder_pick.h: the shell's folder dialog (IFileOpenDialog with FOS_PICKFOLDERS), owned by the
+// game window, on a thread of its own so the present thread that draws the menu keeps running.
+#include <windows.h>
+#include <shobjidl.h>
+#include <stdlib.h>
+#include <string>
+
+extern "C" {
+#include "folder_pick.h"
+#include "host.h"
+#include "input_win.h"
+#include "platform/platform.h"
+}
+
+struct PickReq {
+    std::string start;
+    FolderPickDone done;
+    void *ctx;
+};
+
+static std::wstring wide(const std::string &utf8) {
+    int n = MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), -1, NULL, 0);
+    std::wstring w(n > 0 ? n : 1, L'\0');
+    if (n > 0) MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), -1, &w[0], n);
+    w.resize(wcslen(w.c_str()));
+    return w;
+}
+
+static std::string utf8(const wchar_t *w) {
+    int n = WideCharToMultiByte(CP_UTF8, 0, w, -1, NULL, 0, NULL, NULL);
+    std::string s(n > 0 ? n : 1, '\0');
+    if (n > 0) WideCharToMultiByte(CP_UTF8, 0, w, -1, &s[0], n, NULL, NULL);
+    s.resize(strlen(s.c_str()));
+    return s;
+}
+
+// The dialog wants an absolute folder that exists; anything else leaves it at the shell's last folder.
+static void set_start(IFileOpenDialog *d, const std::string &start) {
+    wchar_t full[MAX_PATH * 2];
+    if (start.empty() || !GetFullPathNameW(wide(start).c_str(), MAX_PATH * 2, full, NULL)) return;
+    IShellItem *item = NULL;
+    if (SUCCEEDED(SHCreateItemFromParsingName(full, NULL, IID_PPV_ARGS(&item)))) {
+        d->SetFolder(item);
+        item->Release();
+    }
+}
+
+static void pick_main(void *arg) {
+    PickReq *r = (PickReq *)arg;
+    std::string chosen;
+    HRESULT co = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);
+    IFileOpenDialog *d = NULL;
+    HRESULT hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&d));
+    if (SUCCEEDED(hr)) {
+        FILEOPENDIALOGOPTIONS opt = 0;
+        d->GetOptions(&opt);
+        d->SetOptions(opt | FOS_PICKFOLDERS | FOS_FORCEFILESYSTEM | FOS_PATHMUSTEXIST);
+        set_start(d, r->start);
+        hr = d->Show(gfx_window_handle());
+        IShellItem *item = NULL;
+        if (SUCCEEDED(hr) && SUCCEEDED(hr = d->GetResult(&item))) {
+            PWSTR path = NULL;
+            if (SUCCEEDED(hr = item->GetDisplayName(SIGDN_FILESYSPATH, &path))) {
+                chosen = utf8(path);
+                CoTaskMemFree(path);
+            }
+            item->Release();
+        }
+        d->Release();
+    }
+    if (FAILED(hr) && hr != HRESULT_FROM_WIN32(ERROR_CANCELLED)) rt_log("folder_pick: the folder dialog failed (0x%08lx)", (unsigned long)hr);
+    r->done(chosen.empty() ? NULL : chosen.c_str(), r->ctx);
+    if (SUCCEEDED(co)) CoUninitialize();
+    delete r;
+}
+
+extern "C" void folder_pick(const char *start, FolderPickDone done, void *ctx) {
+    PickReq *r = new PickReq{start ? start : "", done, ctx};
+    if (!plat_thread_spawn(pick_main, r, "folder dialog", 0)) {
+        rt_log("folder_pick: cannot start the dialog thread");
+        done(NULL, ctx);
+        delete r;
+    }
+}

runtime/gfx_window_sdl.c

@@ -64,6 +64,8 @@ double gfx_window_sdl_density(void) { return __atomic_load_n(&g_density_milli, _
 
 SDL_Window *gfx_window_sdl(void) { return g_win; }
 
+void gfx_window_sdl_run(void (*fn)(void *arg), void *arg) { run_on_window(fn, arg); }
+
 // ---- settings: size and fullscreen
 static char g_applied_size[32];
 static int g_applied_fs;

runtime/input_sdl.h

@@ -11,6 +11,7 @@ extern "C" {
 // gfx_window_sdl.c
 SDL_Window *gfx_window_sdl(void);         // the game window, NULL before gfx_window_start; any thread
 double gfx_window_sdl_density(void);      // pixels per window unit (mouse positions are in units); any thread
+void gfx_window_sdl_run(void (*fn)(void *arg), void *arg);   // runs fn on the window thread and waits; any thread
 
 // input_sdl.c
 void input_sdl_window(SDL_Window *w);     // the game window was created

runtime/ui/amiibo_page.cpp

@@ -17,6 +17,7 @@
 extern "C" {
 #include "amiibo.h"
 #include "cfg.h"
+#include "folder_pick.h"
 #include "platform/platform.h"
 #include "ui_text.h"
 }
@@ -30,7 +31,6 @@ struct FileEntry {
 
 static const char kDefaultAmiiboDir[] = "./amiibo";
 static std::string g_current_dir = kDefaultAmiiboDir;
-static char g_dir_input[512] = "./amiibo";
 static std::vector<FileEntry> g_entries;
 static int g_selected_entry = -1;
 // The last action: a catalog id and the file or folder it names, formatted when drawn (the menu language can change)
@@ -61,10 +61,24 @@ static bool iequals(std::string_view a, std::string_view b) {
 
 static void set_current_dir(const std::string &path) {
     g_current_dir = path;
-    snprintf(g_dir_input, sizeof(g_dir_input), "%s", g_current_dir.c_str());
     cfg_set("TOTK_AMIIBO_DIR", g_current_dir.c_str());
 }
 
+// The host's folder dialog (folder_pick.h) answers on its own thread; the page takes the answer when it draws.
+static PlatMutex g_pick_lock = PLAT_MUTEX_INIT;
+static bool g_pick_open;
+static bool g_pick_ready;
+static std::string g_pick_path;
+
+static void on_folder_picked(const char *path, void *ctx) {
+    (void)ctx;
+    plat_mutex_lock(&g_pick_lock);
+    g_pick_ready = path != NULL;
+    if (path) g_pick_path = path;
+    g_pick_open = false;
+    plat_mutex_unlock(&g_pick_lock);
+}
+
 static void refresh_dir(void) {
     g_entries.clear();
     g_selected_entry = -1;
@@ -122,11 +136,21 @@ void tab_amiibo(float scale) {
         } else {
             g_current_dir = kDefaultAmiiboDir;
         }
-        snprintf(g_dir_input, sizeof(g_dir_input), "%s", g_current_dir.c_str());
         refresh_dir();
         s_inited = true;
     }
 
+    plat_mutex_lock(&g_pick_lock);
+    bool picking = g_pick_open;
+    std::string picked;
+    if (g_pick_ready) picked.swap(g_pick_path);
+    g_pick_ready = false;
+    plat_mutex_unlock(&g_pick_lock);
+    if (!picked.empty()) {
+        set_current_dir(picked);
+        refresh_dir();
+    }
+
     // Two panes: Left (Directory Browser & Tag List), Right (Amiibo Tag Details & Controls)
     const float content_h = ImGui::GetContentRegionAvail().y - opt_bottom();   // Continue and Quit stay visible
     const float left_w = ImGui::GetContentRegionAvail().x * 0.58f;
@@ -136,17 +160,17 @@ void tab_amiibo(float scale) {
     ImGui::BeginChild("##amiibo_explorer", ImVec2(left_w, content_h), true);
     ImGui::TextColored(ImVec4(0.93f, 0.76f, 0.33f, 1.0f), "%s", menu_text(UI_MENU_AMIIBO_DIR));
 
-    ImGui::SetNextItemWidth(ImGui::GetContentRegionAvail().x);
-    if (ImGui::InputText("##amiibo_dir_input", g_dir_input, sizeof(g_dir_input), ImGuiInputTextFlags_EnterReturnsTrue)) {
-        set_current_dir(g_dir_input);
-        refresh_dir();
-    }
+    ImGui::TextWrapped("%s", g_current_dir.c_str());
 
     ImGui::Spacing();
+    ImGui::BeginDisabled(picking);
     if (ImGui::Button(menu_text(UI_MENU_AMIIBO_OPEN))) {
-        set_current_dir(g_dir_input);
-        refresh_dir();
+        plat_mutex_lock(&g_pick_lock);
+        g_pick_open = true;
+        plat_mutex_unlock(&g_pick_lock);
+        folder_pick(g_current_dir.c_str(), on_folder_picked, NULL);
     }
+    ImGui::EndDisabled();
     ImGui::SameLine();
     if (ImGui::Button(menu_text(UI_MENU_AMIIBO_DEFAULT_DIR))) {
         set_current_dir(kDefaultAmiiboDir);
@@ -161,6 +185,11 @@ void tab_amiibo(float scale) {
     ImGui::TextDisabled("%s", menu_text(UI_MENU_AMIIBO_PICK));
 
     ImGui::BeginChild("##file_list", ImVec2(0, 0), true);
+    if (g_status_id == UI_MENU_AMIIBO_NO_DIR) {
+        char missing[512];
+        snprintf(missing, sizeof missing, menu_text(UI_MENU_AMIIBO_NO_DIR), g_current_dir.c_str());
+        ImGui::TextWrapped("%s", missing);
+    }
     for (size_t i = 0; i < g_entries.size(); i++) {
         const auto &e = g_entries[i];
         std::string label = e.is_dir ? e.name + "/" : e.name;

tools/build_game.py

@@ -115,7 +115,7 @@ if WIN:
     RT_FLAGS.append('-D_WIN32_WINNT=0x0A00')
     # -Xlinker passes the map path as one argument; -Wl, would split it at any comma in the build dir path
     LINK_FLAGS = ['-fuse-ld=lld', '-Wl,--stack,16777216', '-Xlinker', '"--Map=$builddir/totk.map"']   # the map feeds tools/prof_report.py
-    LINK_LIBS = ['-lpsapi', '-lbcrypt', '-lvulkan-1', '-luser32', '-lgdi32', '-ldwmapi', '-limm32', '-lwinmm', '-lSDL3', '-lopus', '-l:libvpx.a', '-l:libzstd.a', '-l:libstdc++.a', '-l:libwinpthread.a']   # Vulkan back end; libvpx static (movies); libzstd static (resolution.c)
+    LINK_LIBS = ['-lpsapi', '-lbcrypt', '-lvulkan-1', '-luser32', '-lgdi32', '-ldwmapi', '-limm32', '-lwinmm', '-lole32', '-lshell32', '-luuid', '-lSDL3', '-lopus', '-l:libvpx.a', '-l:libzstd.a', '-l:libstdc++.a', '-l:libwinpthread.a']   # Vulkan back end; libvpx static (movies); libzstd static (resolution.c)
     VMA_INCLUDE = UCRT.parent / 'include' / 'vma'   # vk_mem_alloc.h; MSYS2 package vulkan-memory-allocator
 else:
     # -no-pie: the lifted modules' function tables (hundreds of thousands of pointers) need no load-time relocation.
@@ -151,7 +151,7 @@ def vma_include():
 
 
 # --toolchain: an llvm-mingw tree. The libraries, headers and DLLs MSYS2 supplies come from the deps directory instead.
-LLVM_LINK_LIBS = ['-lpsapi', '-lbcrypt', '-luser32', '-lgdi32', '-ldwmapi', '-limm32', '-lwinmm', '-lvulkan-1', '-lSDL3', '-lopus',
+LLVM_LINK_LIBS = ['-lpsapi', '-lbcrypt', '-luser32', '-lgdi32', '-ldwmapi', '-limm32', '-lwinmm', '-lole32', '-lshell32', '-luuid', '-lvulkan-1', '-lSDL3', '-lopus',
                   '-l:libvpx.a', '-l:libzstd.a', '-l:libc++.a', '-l:libc++abi.a', '-l:libunwind.a', '-l:libwinpthread.a']
 DEFAULT_DEPS = ROOT / 'toolchain' / 'deps-mingw'
 # Runtime sources compiled per install, not in the library: romfs.c includes romfs_config.h, patches.c and ov_zstd.c