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Add a platform OpenGL context.#183715

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auto-submit[bot] merged 2 commits intoflutter:masterfrom
robert-ancell:linux-platform-context
Mar 16, 2026
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Add a platform OpenGL context.#183715
auto-submit[bot] merged 2 commits intoflutter:masterfrom
robert-ancell:linux-platform-context

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@robert-ancell
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Switch the compositor from using the engine OpenGL context to a new context for the platform thread. When creating windows with the new multi-window API (calls come from Dart code) the FlView would try and make shaders but fail since the engine context was already current.

This would show when running the multiple_windows example as: ** (com.example.multiple_windows:1244082): WARNING **: 14:09:30.400: Failed to setup compositor shaders, unable to make OpenGL context current

Switch the compositor from using the engine OpenGL context to a new
context for the platform thread. When creating windows with the new
multi-window API (calls come from Dart code) the FlView would try
and make shaders but fail since the engine context was already current.

This would show when running the multiple_windows example as:
** (com.example.multiple_windows:1244082): WARNING **: 14:09:30.400: Failed to setup compositor shaders, unable to make OpenGL context current
@robert-ancell robert-ancell requested a review from a team as a code owner March 16, 2026 01:10
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It looks like this pull request may not have tests. Please make sure to add tests or get an explicit test exemption before merging.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing. If you believe this PR qualifies for a test exemption, contact "@test-exemption-reviewer" in the #hackers channel in Discord (don't just cc them here, they won't see it!). The test exemption team is a small volunteer group, so all reviewers should feel empowered to ask for tests, without delegating that responsibility entirely to the test exemption group.

@github-actions github-actions bot added engine flutter/engine related. See also e: labels. platform-linux Building on or for Linux specifically a: desktop Running on desktop team-linux Owned by the Linux platform team labels Mar 16, 2026
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Code Review

This pull request introduces a dedicated OpenGL context for the platform thread to address context contention issues in multi-window scenarios. The changes involve creating a new platform_context in FlOpenGLManager, providing a function to make it current, and utilizing this new context within FlCompositorOpenGL for shader operations. The approach is sound and directly resolves the issue described. I have one suggestion to enhance robustness by adding error handling for the new context's creation.

@robert-ancell robert-ancell requested a review from mattkae March 16, 2026 02:04
@mattkae mattkae added the CICD Run CI/CD label Mar 16, 2026
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👍

@robert-ancell robert-ancell added the autosubmit Merge PR when tree becomes green via auto submit App label Mar 16, 2026
@auto-submit auto-submit bot added this pull request to the merge queue Mar 16, 2026
Merged via the queue into flutter:master with commit cbf31c8 Mar 16, 2026
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@flutter-dashboard flutter-dashboard bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Mar 16, 2026
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@robert-ancell Sorry for the late review. On Windows we structured things such that all platform thread work on the engine's OpenGL context is done before the engine is initialized. Is that approach not feasible for Linux?

@robert-ancell robert-ancell deleted the linux-platform-context branch March 17, 2026 00:33
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This is occurring when we make the FFI calls from Dart. The engine has made the render context current, but not cleared it. So when _window_linux.dart creates a view it tries to access the same render context from another thread and fails. Views can be created at any point so this has to be done after the engine is initialized. We have to perform some OpenGL shader setup for each GTK view, I suspect this is not required in the Windows embedder.

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We have to perform some OpenGL shader setup for each GTK view, I suspect this is not required in the Windows embedder.

@robert-ancell Just curious, why can't we use the same shader for all views?

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Mar 17, 2026
auto-submit bot pushed a commit to flutter/packages that referenced this pull request Mar 18, 2026
Roll Flutter from 732e05dd483c to d117642c18e0 (47 revisions)

flutter/flutter@732e05d...d117642

2026-03-17 [email protected] Roll Skia from fa3bb1f60d99 to dba893a44d7a (1 revision) (flutter/flutter#183783)
2026-03-17 [email protected] [ios][pv]fix admob banner scrollable on ios 18.2 (flutter/flutter#183274)
2026-03-17 [email protected] Roll Packages from 0f2eeae to a9d36fb (2 revisions) (flutter/flutter#183782)
2026-03-17 [email protected] Update goldctl version (flutter/flutter#183538)
2026-03-17 [email protected] Roll Skia from 69be1087807b to fa3bb1f60d99 (1 revision) (flutter/flutter#183779)
2026-03-17 [email protected] Roll Dart SDK from 38dedf00c2cd to 30cdd2634429 (1 revision) (flutter/flutter#183778)
2026-03-17 [email protected] Roll Fuchsia Linux SDK from s7rq9m8tH2aZtX-kP... to zYBvfzIH95BY3cCzL... (flutter/flutter#183777)
2026-03-17 [email protected] Roll Skia from 4ea039236580 to 69be1087807b (2 revisions) (flutter/flutter#183772)
2026-03-17 [email protected] Roll Skia from fb402093cfb5 to 4ea039236580 (1 revision) (flutter/flutter#183770)
2026-03-17 [email protected] Roll Skia from d6bc6d17d637 to fb402093cfb5 (8 revisions) (flutter/flutter#183765)
2026-03-17 [email protected] Roll Dart SDK from ff50ab8ecea4 to 38dedf00c2cd (2 revisions) (flutter/flutter#183764)
2026-03-17 [email protected] Wrap EGL image usage in a GObject (flutter/flutter#183539)
2026-03-17 [email protected] Adds platform_view_test_macos_impeller (flutter/flutter#183760)
2026-03-17 [email protected] Adds flush to metal screenshotter. (flutter/flutter#183758)
2026-03-16 [email protected] Add a platform OpenGL context. (flutter/flutter#183715)
2026-03-16 [email protected] Fix formatting, capitalization, and grammar in activation issue template (flutter/flutter#183061)
2026-03-16 [email protected] Roll Dart SDK from 4a6febbf882e to ff50ab8ecea4 (2 revisions) (flutter/flutter#183739)
2026-03-16 [email protected] docs: add code review guidance to CONTRIBUTING.md (flutter/flutter#182778)
2026-03-16 [email protected] Filter 'waiting for customer response' issues from macOS triage (flutter/flutter#183552)
2026-03-16 [email protected] Adds github action to reset cicd when new branches come (flutter/flutter#183675)
2026-03-16 [email protected] Adds macos impeller complex layout performance test (flutter/flutter#183669)
2026-03-16 [email protected] Roll Dart SDK from b74e5b537d71 to 4a6febbf882e (2 revisions) (flutter/flutter#183695)
2026-03-16 [email protected] Use properties to configure leak_tracking and test_randomization_off in .ci.yaml (flutter/flutter#183605)
2026-03-16 [email protected] [flutter_tools] Avoid File.exists and File.stat, as per enforced lint rule (flutter/flutter#183463)
2026-03-16 [email protected] Properly parse URIs for testPath when the host is running on Windows. (flutter/flutter#176881)
2026-03-16 [email protected] Roll Packages from 91f7c33 to 0f2eeae (6 revisions) (flutter/flutter#183730)
2026-03-16 [email protected] Roll Skia from a6ccaf95c6e0 to d6bc6d17d637 (5 revisions) (flutter/flutter#183726)
2026-03-16 [email protected] Roll Fuchsia Linux SDK from WOfyEFkxf9JX26VS-... to s7rq9m8tH2aZtX-kP... (flutter/flutter#183723)
2026-03-15 [email protected] Roll Skia from 34ace196b838 to a6ccaf95c6e0 (2 revisions) (flutter/flutter#183712)
2026-03-14 [email protected] Roll Fuchsia Linux SDK from vAWG8mRvsQHblDBsy... to WOfyEFkxf9JX26VS-... (flutter/flutter#183694)
2026-03-14 [email protected] Roll Skia from 06106120c6bf to 34ace196b838 (1 revision) (flutter/flutter#183677)
2026-03-14 [email protected] Roll Dart SDK from 6a3dc9d4f881 to b74e5b537d71 (2 revisions) (flutter/flutter#183676)
2026-03-14 [email protected] Add some quality of life improvements to the release GitHub workflows. (flutter/flutter#183658)
2026-03-14 [email protected] Fix RouteAware.didPushNext documentation inaccuracy (flutter/flutter#183097)
2026-03-13 [email protected] Adds complex layout impeller startup benchmark (flutter/flutter#183655)
2026-03-13 [email protected] Adds switch for sdf rendering plus golden tests (flutter/flutter#183543)
2026-03-13 [email protected] Made complex_layout_scroll_perf explicitly skia (flutter/flutter#183663)
2026-03-13 [email protected] Update android integration test to match the current android semantics (flutter/flutter#183548)
2026-03-13 [email protected] Roll Skia from 6c0346103c24 to 06106120c6bf (3 revisions) (flutter/flutter#183654)
2026-03-13 [email protected] Roll Dart SDK from d5f6d3c17499 to 6a3dc9d4f881 (1 revision) (flutter/flutter#183652)
2026-03-13 [email protected] Fix PinnedHeaderSliver semantics focus capture (flutter/flutter#179023)
2026-03-13 [email protected] [a11y][android] In Android 16, sendWindowContentChangeEvent when check state changes (flutter/flutter#183606)
2026-03-13 [email protected] Update gradle utils to know about kgp 2.3.10 constraints (flutter/flutter#183416)
2026-03-13 [email protected] Roll Skia from 029229d8be91 to 6c0346103c24 (5 revisions) (flutter/flutter#183648)
2026-03-13 [email protected] Roll Fuchsia Linux SDK from jJbpv4J_tjW-wuKDq... to vAWG8mRvsQHblDBsy... (flutter/flutter#183646)
2026-03-13 [email protected] [flutter_tools] Support flavors and transformers for shaders (flutter/flutter#181889)
...
@robert-ancell
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@robert-ancell Just curious, why can't we use the same shader for all views?

That's a good point - I think we just ended up this way due to the single view history. We should change this: #183911

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