fix(gamescope): keep Fill scaling and magnification visible (#1634)

* fix(gamescope): preserve signed plane positions * fix(gamescope): pin validated scaling component
2026-11-12 03:21:08 +00:00 · 2026-10-26 16:06:40 -04:00
1 parent aa17b0553d
commit 73daaf7adc
@@ -99,3 +99,25 @@ The patch can keep the result for `DROIDDECK_WSI_BYPASS_CHECK_MS` milliseconds.
 or 0 keeps the per-present check; the app sets 100 only in Performance mode and 0
 otherwise. With 100, a window resize or a flip/obscure change is seen up to 100 ms
 later than before; surface creation and capability queries still check every time.
+
+## 0118 Wayland: preserve signed plane positions
+
+Fill scaling and Steam magnification can place the image at negative x/y coordinates.
+The Wayland backend converted these signed positions through an unsigned size helper:
+at host scale 120, -120 became 35791275 and the image moved off-screen while overlays
+could remain visible. A separate signed conversion uses a 64-bit intermediate and
+retains the existing ceiling convention; viewport sizes keep their original helper.
+
+The component build runs `wayland_scaling` for negative crop offsets, positive/zero
+positions, fractional host scales and wide intermediates. This patch may be worth
+upstreaming: the same unsigned position calls were present in ValveSoftware/gamescope
+3.16.29 and master `d175688ad4ec490dc7b0695c5c62f8807684a1f1` when checked on
+2026-10-26. Carry it here until an upstream release containing the fix is adopted.
+
+Device validation on AYN Thor (1280x720 session, 1920x1080 Android output):
+800x600 and 1600x600 source windows retained their image through Auto, Fit,
+Stretch, Fill, Integer and 2x Steam magnification, including returning to Fit.
+The old component lost the image in Fill and magnification. The tested executable
+matches the pinned p14 archive and the locally assembled APK. Hardware checks used
+native Gamescope properties; the physical Back+LB shortcut was not independently
+confirmed. The original APK and runtime were restored after validation.
@@ -39,7 +39,7 @@ else
 fi
 PREP
 makepkg -A -s --noconfirm --skipchecksums --skippgpcheck
-meson test -C src/build --no-rebuild --print-errorlogs cursor_routing
+meson test -C src/build --no-rebuild --print-errorlogs cursor_routing wayland_scaling
 ls -l *.pkg.tar.*
 "
 cd "$WORK"
@@ -0,0 +1,106 @@
+diff --git a/src/Backends/WaylandBackend.cpp b/src/Backends/WaylandBackend.cpp
+index d00644f..40164ba 100644
+--- a/src/Backends/WaylandBackend.cpp
+++ b/src/Backends/WaylandBackend.cpp
+@@ -11,6 +11,7 @@
+ #include "waitable.h"
+ #include "Utils/TempFiles.h"
+ #include "Utils/CursorRouting.h"
+#include "Utils/WaylandScaling.h"
+ 
+ #include <cstring>
+ #include <unordered_map>
+@@ -1618,8 +1619,8 @@ namespace gamescope
+             {
+                 wl_subsurface_set_position(
+                     m_pSubsurface,
+-                    WaylandScaleToLogical( oState->nDestX, uScale ),
+-                    WaylandScaleToLogical( oState->nDestY, uScale ) );
+                    gamescope::WaylandPositionToLogical( oState->nDestX, uScale ),
+                    gamescope::WaylandPositionToLogical( oState->nDestY, uScale ) );
+             }
+             // The x/y here does nothing? Why? What is it for...
+             // Use the subsurface set_position thing instead.
+diff --git a/src/Utils/WaylandScaling.h b/src/Utils/WaylandScaling.h
+new file mode 100644
+index 0000000..d488e39
+--- /dev/null
+++ b/src/Utils/WaylandScaling.h
+@@ -0,0 +1,12 @@
+#pragma once
+
+#include <cstdint>
+
+namespace gamescope
+{
+    constexpr int32_t WaylandPositionToLogical( int32_t nValue, uint32_t uFactor )
+    {
+        const int64_t nScaled = int64_t( nValue ) * 120;
+        return int32_t( nScaled / uFactor + ( nScaled % uFactor > 0 ) );
+    }
+}
+diff --git a/tests/meson.build b/tests/meson.build
+index 1ccdf7d..d86bf9e 100644
+--- a/tests/meson.build
+++ b/tests/meson.build
+@@ -8,7 +8,7 @@ endforeach
+ 
+ gamescope_tests = executable(
+ 	'gamescope_tests',
+-	unittest_src + ['test_convar.cpp', 'test_cursor_routing.cpp', 'test_focus_placement.cpp', 'test_mangoapp_config.cpp', 'test_mangoapp_control.cpp', 'test_process.cpp', 'test_upscale.cpp', 'test_utils_parsers.cpp', 'test_utils_string.cpp', 'test_vrclient_detect.cpp'],
+	unittest_src + ['test_convar.cpp', 'test_cursor_routing.cpp', 'test_focus_placement.cpp', 'test_mangoapp_config.cpp', 'test_mangoapp_control.cpp', 'test_process.cpp', 'test_upscale.cpp', 'test_utils_parsers.cpp', 'test_utils_string.cpp', 'test_vrclient_detect.cpp', 'test_wayland_scaling.cpp'],
+ 	include_directories: [srcdir, sol2_include],
+ 	dependencies: [catch2_dep, luajit_dep, cap_dep, drm_dep, glm_dep, wlroots_dep],
+ 	cpp_args: gamescope_cpp_args,
+@@ -18,6 +18,7 @@ reaper_test_helper = executable('reaper_test_helper', 'reaper_test_helper.cpp')
+ 
+ test('convar', gamescope_tests, args: ['[convar]'])
+ test('cursor_routing', gamescope_tests, args: ['[cursor_routing]'])
+test('wayland_scaling', gamescope_tests, args: ['[wayland_scaling]'])
+ test('focus_placement', gamescope_tests, args: ['[focus_placement]'])
+ test('mangoapp_config', gamescope_tests, args: ['[mangoapp_config]'])
+ test('mangoapp_control', gamescope_tests, args: ['[mangoapp_control]'])
+diff --git a/tests/test_wayland_scaling.cpp b/tests/test_wayland_scaling.cpp
+new file mode 100644
+index 0000000..498f55b
+--- /dev/null
+++ b/tests/test_wayland_scaling.cpp
+@@ -0,0 +1,38 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "Utils/WaylandScaling.h"
+
+#include <cmath>
+#include <limits>
+
+using namespace gamescope;
+
+TEST_CASE("cropped Wayland planes retain negative positions", "[wayland_scaling]")
+{
+    REQUIRE( WaylandPositionToLogical( -120, 120 ) == -120 );
+    REQUIRE( WaylandPositionToLogical( -640, 120 ) == -640 );
+    REQUIRE( WaylandPositionToLogical( -360, 120 ) == -360 );
+    REQUIRE( WaylandPositionToLogical( 0, 120 ) == 0 );
+    REQUIRE( WaylandPositionToLogical( 160, 120 ) == 160 );
+}
+
+TEST_CASE("Wayland positions round up at fractional host scales", "[wayland_scaling]")
+{
+    const int32_t positions[] = { -100000000, -1000000, -640, -120, -1, 0, 1, 120, 640, 1000000, 100000000 };
+    const uint32_t scales[] = { 120, 150, 180, 240, 360, 480 };
+    for ( uint32_t uScale : scales )
+    {
+        for ( int32_t nPosition : positions )
+        {
+            CAPTURE( nPosition, uScale );
+            const int32_t nExpected = int32_t( std::ceil( (long double)( nPosition ) * 120 / uScale ) );
+            REQUIRE( WaylandPositionToLogical( nPosition, uScale ) == nExpected );
+        }
+    }
+}
+
+TEST_CASE("Wayland position conversion widens before multiplying", "[wayland_scaling]")
+{
+    REQUIRE( WaylandPositionToLogical( std::numeric_limits<int32_t>::min(), 120 ) == std::numeric_limits<int32_t>::min() );
+    REQUIRE( WaylandPositionToLogical( std::numeric_limits<int32_t>::max(), 120 ) == std::numeric_limits<int32_t>::max() );
+}
@@ -1,3 +1,3 @@
 GAMESCOPE_REPO=Droid-Deck/DroidDeck-Components
-GAMESCOPE_TAG=gamescope-3.16.29-p13
-GAMESCOPE_SHA256=93c789dc9e08828496f1caa2849d56acdf205838de723a24b296547a29c0b6af
+GAMESCOPE_TAG=gamescope-3.16.29-p14
+GAMESCOPE_SHA256=f0f2f33767c883bcfe66f28c303fddc1564f91a915fb7cedd31eb823570b254c