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Fix black window in the subsurface view renderer - #191850
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FlViewRendererSubsurface is the default renderer on Wayland, so Flutter apps
running with Impeller on Mesa drivers currently show nothing but a black
window.
It picked its framebuffer format from
epoxy_has_gl_extension("GL_EXT_texture_format_BGRA8888"), which asks what the
driver is capable of rather than what the engine actually rendered. The frame
was composited into a BGRA framebuffer while the engine had rendered RGBA, so
nothing reached the screen. The failure is silent: the framebuffer is
complete, no GL errors are raised, and the Wayland surface is committed as
normal.
That check used to be correct, and was invalidated by 5f97c7f ("Fixes MSAA
on the linux embedder", flutter#191379) in two ways:
- It replaced the identical check in fl_opengl_frame.cc with one that reads
the format the engine reported in the layer's backing store, making the
extension check the stale copy of a rule that had moved on.
- It made the engine render RGBA even where the extension is advertised. With
Impeller the backing store is now allocated by
fl_framebuffer_new_multisample(), whose offscreen MSAA path attaches a
multisample renderbuffer of GL_RGBA8 and no texture, and fl_engine.cc
reports GL_RGBA8 for those. Driver capability and rendered format are
therefore no longer the same question.
FlViewRendererSubsurface was written before that landed and merged cleanly
after it, in 706edcd ("Add FlViewRendererSubsurface", flutter#191389), because
the two changes touch different files and so never conflicted textually.
Move the rule into fl_compositor_opengl_get_frame_format() and use it from
both paths so they cannot disagree again. fl_engine.cc remains the only place
that chooses a format; both consumers now follow what it reports. Every
backing store in a frame is created from context-wide capabilities, so they
all share a format, and the first one describes the frame. Take it from the
first backing store rather than the first layer, as platform views carry no
format and would otherwise decide it by being drawn first.
The bug is not reachable from a unit test, as presenting a frame requires a
realized Wayland subsurface and the tests run on X11, so test the shared
function directly, including that an advertised extension does not change its
result.
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This pull request introduces fl_compositor_opengl_get_frame_format to determine the texture format for compositing layers based on their backing stores, replacing ad-hoc format detection in fl_opengl_frame.cc and fl_view_renderer_subsurface.cc. Feedback highlights an issue where open_gl.framebuffer.target is accessed without verifying open_gl.type, which is unsafe when the backing store is a texture. Additionally, the feedback recommends updating the new unit tests to explicitly initialize open_gl.type to match the active union member being tested.
FlutterOpenGLBackingStore is a union discriminated by open_gl.type, so framebuffer.target is only meaningful when that type is kFlutterOpenGLTargetTypeFramebuffer. Check it before reading, and fall back to RGBA otherwise. fl_engine.cc only ever creates framebuffer backing stores, so this does not change behaviour, but it keeps the function from reporting a format read out of an inactive union member. The existing tests built backing stores with a framebuffer but left open_gl.type zeroed, which is kFlutterOpenGLTargetTypeTexture, so they described something the engine never produces. Set the type they mean.
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flutter/flutter@e8dca90...8d8c1aa 2026-08-28 [email protected] Roll Packages from bd3cbc1 to cd4cdd0 (15 revisions) (flutter/flutter#191965) 2026-08-28 [email protected] Bump customer testing version to pick up forui tests (flutter/flutter#191931) 2026-08-28 [email protected] Use leading scroll offset instead of infinite offset to reveal pinned slivers (flutter/flutter#191329) 2026-08-28 [email protected] Roll Skia from 21f71051e749 to fe0b9a5261f9 (1 revision) (flutter/flutter#191960) 2026-08-28 [email protected] Share the common Linux window controller code in mixins (flutter/flutter#191930) 2026-08-28 [email protected] Roll Dart SDK from 2cf2f69fd9f0 to ae63a6eca3f1 (1 revision) (flutter/flutter#191953) 2026-08-28 [email protected] Roll Skia from 11e3a7cb0fd0 to 21f71051e749 (3 revisions) (flutter/flutter#191942) 2026-08-28 [email protected] Roll Dart SDK from e030e77d5413 to 2cf2f69fd9f0 (2 revisions) (flutter/flutter#191934) 2026-08-28 [email protected] Remove no-shuffle in flutter tools overall experience test (flutter/flutter#191861) 2026-08-28 [email protected] [flutter_tools] Gracefully handle Windows Application Control and security policy execution blocks (flutter/flutter#191912) 2026-08-28 [email protected] [tool] Migrate ConfigCommand to modular dependency injection (flutter/flutter#190743) 2026-08-28 [email protected] Roll Skia from 37459da0a755 to 11e3a7cb0fd0 (9 revisions) (flutter/flutter#191929) 2026-08-28 [email protected] Connect to moved-to-rect after the window is realized (flutter/flutter#191773) 2026-08-28 [email protected] macOS: Compare accessibility strings as NSStrings in tests (flutter/flutter#191853) 2026-08-28 [email protected] macOS: Record test accessibility notifications in a dictionary (flutter/flutter#191854) 2026-08-28 [email protected] Roll Fuchsia Test Scripts from 6SXRz6wsA2Zm_rAqP... to u_fSMsPU22VvUsvSo... (flutter/flutter#191927) 2026-08-28 [email protected] Roll Dart SDK from cb4c39d067f3 to e030e77d5413 (3 revisions) (flutter/flutter#191923) 2026-08-27 [email protected] Migrate ios driver tests batch 2 to simulators (flutter/flutter#190930) 2026-08-27 [email protected] [flutter_test] Ensure LiveTestWidgetsFlutterBinding executes frame and pointer callbacks in the test zone (flutter/flutter#191595) 2026-08-27 [email protected] Deprecate legacy gen_defaults tool (flutter/flutter#191911) 2026-08-27 [email protected] Fix black window in the subsurface view renderer (flutter/flutter#191850) 2026-08-27 [email protected] Roll Skia from 82e972ea84b1 to 37459da0a755 (10 revisions) (flutter/flutter#191906) 2026-08-27 [email protected] iOS: Key the platform view factory registries by NSString (flutter/flutter#191855) 2026-08-27 [email protected] Sync CHANGELOG.md from stable (flutter/flutter#191895) 2026-08-27 [email protected] [flutter_tools] Honor configured build-dir across flutter project and build targets (flutter/flutter#191592) 2026-08-27 [email protected] Revert: Handle linear and radial gradients in UberSDF (flutter/flutter#191913) 2026-08-27 [email protected] Explicitly disable HCPP in hybrid_android_views integration test (flutter/flutter#191894) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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…r#12679) flutter/flutter@e8dca90...8d8c1aa 2026-08-28 [email protected] Roll Packages from bd3cbc1 to cd4cdd0 (15 revisions) (flutter/flutter#191965) 2026-08-28 [email protected] Bump customer testing version to pick up forui tests (flutter/flutter#191931) 2026-08-28 [email protected] Use leading scroll offset instead of infinite offset to reveal pinned slivers (flutter/flutter#191329) 2026-08-28 [email protected] Roll Skia from 21f71051e749 to fe0b9a5261f9 (1 revision) (flutter/flutter#191960) 2026-08-28 [email protected] Share the common Linux window controller code in mixins (flutter/flutter#191930) 2026-08-28 [email protected] Roll Dart SDK from 2cf2f69fd9f0 to ae63a6eca3f1 (1 revision) (flutter/flutter#191953) 2026-08-28 [email protected] Roll Skia from 11e3a7cb0fd0 to 21f71051e749 (3 revisions) (flutter/flutter#191942) 2026-08-28 [email protected] Roll Dart SDK from e030e77d5413 to 2cf2f69fd9f0 (2 revisions) (flutter/flutter#191934) 2026-08-28 [email protected] Remove no-shuffle in flutter tools overall experience test (flutter/flutter#191861) 2026-08-28 [email protected] [flutter_tools] Gracefully handle Windows Application Control and security policy execution blocks (flutter/flutter#191912) 2026-08-28 [email protected] [tool] Migrate ConfigCommand to modular dependency injection (flutter/flutter#190743) 2026-08-28 [email protected] Roll Skia from 37459da0a755 to 11e3a7cb0fd0 (9 revisions) (flutter/flutter#191929) 2026-08-28 [email protected] Connect to moved-to-rect after the window is realized (flutter/flutter#191773) 2026-08-28 [email protected] macOS: Compare accessibility strings as NSStrings in tests (flutter/flutter#191853) 2026-08-28 [email protected] macOS: Record test accessibility notifications in a dictionary (flutter/flutter#191854) 2026-08-28 [email protected] Roll Fuchsia Test Scripts from 6SXRz6wsA2Zm_rAqP... to u_fSMsPU22VvUsvSo... (flutter/flutter#191927) 2026-08-28 [email protected] Roll Dart SDK from cb4c39d067f3 to e030e77d5413 (3 revisions) (flutter/flutter#191923) 2026-08-27 [email protected] Migrate ios driver tests batch 2 to simulators (flutter/flutter#190930) 2026-08-27 [email protected] [flutter_test] Ensure LiveTestWidgetsFlutterBinding executes frame and pointer callbacks in the test zone (flutter/flutter#191595) 2026-08-27 [email protected] Deprecate legacy gen_defaults tool (flutter/flutter#191911) 2026-08-27 [email protected] Fix black window in the subsurface view renderer (flutter/flutter#191850) 2026-08-27 [email protected] Roll Skia from 82e972ea84b1 to 37459da0a755 (10 revisions) (flutter/flutter#191906) 2026-08-27 [email protected] iOS: Key the platform view factory registries by NSString (flutter/flutter#191855) 2026-08-27 [email protected] Sync CHANGELOG.md from stable (flutter/flutter#191895) 2026-08-27 [email protected] [flutter_tools] Honor configured build-dir across flutter project and build targets (flutter/flutter#191592) 2026-08-27 [email protected] Revert: Handle linear and radial gradients in UberSDF (flutter/flutter#191913) 2026-08-27 [email protected] Explicitly disable HCPP in hybrid_android_views integration test (flutter/flutter#191894) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
victorsanni
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Sep 9, 2026
…r#12679) flutter/flutter@e8dca90...8d8c1aa 2026-08-28 [email protected] Roll Packages from bd3cbc1 to cd4cdd0 (15 revisions) (flutter/flutter#191965) 2026-08-28 [email protected] Bump customer testing version to pick up forui tests (flutter/flutter#191931) 2026-08-28 [email protected] Use leading scroll offset instead of infinite offset to reveal pinned slivers (flutter/flutter#191329) 2026-08-28 [email protected] Roll Skia from 21f71051e749 to fe0b9a5261f9 (1 revision) (flutter/flutter#191960) 2026-08-28 [email protected] Share the common Linux window controller code in mixins (flutter/flutter#191930) 2026-08-28 [email protected] Roll Dart SDK from 2cf2f69fd9f0 to ae63a6eca3f1 (1 revision) (flutter/flutter#191953) 2026-08-28 [email protected] Roll Skia from 11e3a7cb0fd0 to 21f71051e749 (3 revisions) (flutter/flutter#191942) 2026-08-28 [email protected] Roll Dart SDK from e030e77d5413 to 2cf2f69fd9f0 (2 revisions) (flutter/flutter#191934) 2026-08-28 [email protected] Remove no-shuffle in flutter tools overall experience test (flutter/flutter#191861) 2026-08-28 [email protected] [flutter_tools] Gracefully handle Windows Application Control and security policy execution blocks (flutter/flutter#191912) 2026-08-28 [email protected] [tool] Migrate ConfigCommand to modular dependency injection (flutter/flutter#190743) 2026-08-28 [email protected] Roll Skia from 37459da0a755 to 11e3a7cb0fd0 (9 revisions) (flutter/flutter#191929) 2026-08-28 [email protected] Connect to moved-to-rect after the window is realized (flutter/flutter#191773) 2026-08-28 [email protected] macOS: Compare accessibility strings as NSStrings in tests (flutter/flutter#191853) 2026-08-28 [email protected] macOS: Record test accessibility notifications in a dictionary (flutter/flutter#191854) 2026-08-28 [email protected] Roll Fuchsia Test Scripts from 6SXRz6wsA2Zm_rAqP... to u_fSMsPU22VvUsvSo... (flutter/flutter#191927) 2026-08-28 [email protected] Roll Dart SDK from cb4c39d067f3 to e030e77d5413 (3 revisions) (flutter/flutter#191923) 2026-08-27 [email protected] Migrate ios driver tests batch 2 to simulators (flutter/flutter#190930) 2026-08-27 [email protected] [flutter_test] Ensure LiveTestWidgetsFlutterBinding executes frame and pointer callbacks in the test zone (flutter/flutter#191595) 2026-08-27 [email protected] Deprecate legacy gen_defaults tool (flutter/flutter#191911) 2026-08-27 [email protected] Fix black window in the subsurface view renderer (flutter/flutter#191850) 2026-08-27 [email protected] Roll Skia from 82e972ea84b1 to 37459da0a755 (10 revisions) (flutter/flutter#191906) 2026-08-27 [email protected] iOS: Key the platform view factory registries by NSString (flutter/flutter#191855) 2026-08-27 [email protected] Sync CHANGELOG.md from stable (flutter/flutter#191895) 2026-08-27 [email protected] [flutter_tools] Honor configured build-dir across flutter project and build targets (flutter/flutter#191592) 2026-08-27 [email protected] Revert: Handle linear and radial gradients in UberSDF (flutter/flutter#191913) 2026-08-27 [email protected] Explicitly disable HCPP in hybrid_android_views integration test (flutter/flutter#191894) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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FlViewRendererSubsurface is the default renderer on Wayland, so Flutter apps running with Impeller on Mesa drivers currently show nothing but a black window.
It picked its framebuffer format from
epoxy_has_gl_extension("GL_EXT_texture_format_BGRA8888"), which asks what the driver is capable of rather than what the engine actually rendered. The frame was composited into a BGRA framebuffer while the engine had rendered RGBA, so nothing reached the screen. The failure is silent: the framebuffer is complete, no GL errors are raised, and the Wayland surface is committed as normal.
That check used to be correct, and was invalidated by 5f97c7f ("Fixes MSAA on the linux embedder", #191379) in two ways:
FlViewRendererSubsurface was written before that landed and merged cleanly after it, in 706edcd ("Add FlViewRendererSubsurface", #191389), because the two changes touch different files and so never conflicted textually.
Move the rule into fl_compositor_opengl_get_frame_format() and use it from both paths so they cannot disagree again. fl_engine.cc remains the only place that chooses a format; both consumers now follow what it reports. Every backing store in a frame is created from context-wide capabilities, so they all share a format, and the first one describes the frame. Take it from the first backing store rather than the first layer, as platform views carry no format and would otherwise decide it by being drawn first.
The bug is not reachable from a unit test, as presenting a frame requires a realized Wayland subsurface and the tests run on X11, so test the shared function directly, including that an advertised extension does not change its result.