[android_hardware_smoke_test] Synchronize platform view compositing by andywolff · Pull Request #189151 · flutter/flutter

andywolff · 2026-07-08T19:58:44Z

Fixes #189079 - one in 100 runs failed with blank/black golden screenshots on the Vulkan backend for platform view tests in the android_hardware_smoke_test integration test suite.

Previously, the driver tests (goldens.dart) hardcoded a 3 frame wait before screenshotting. In CI, native views occasionally did not paint that quickly, causing blank screenshot failures.

To resolve this, we replace the hardcoded wait with a native drawing synchronization mechanism: the Kotlin TextView subclass overrides onDraw to notify Dart over Method Channels when it paints. I tried a tree-wide OnDrawListener, but it fired too early, so I went with this. Dart awaits this draw signal followed by 1 frame to ensure the compositor submits the frame before capturing coordinates.

Verified on my local device by temporarily marking the native view as invisible for 3 seconds. Tests produced black screens before this change and correct results after this change.

Pre-launch Checklist

Replace the hardcoded 3-frame wait in platform view tests with a native draw event listener to prevent intermittent black screenshot failures.

andywolff · 2026-07-08T20:01:17Z

started staging runs

Vulkan Shard ( Linux_android_emu_vulkan_stable android_hardware_smoke_vulkan_tests ): https://ci.chromium.org/b/8676815650908894593

OpenGL ES Shard ( Linux_android_emu android_hardware_smoke_opengles_tests ): https://ci.chromium.org/b/8676815638421172241

andywolff · 2026-07-08T20:01:26Z

/gemini review

gemini-code-assist

Code Review

This pull request modifies the Android hardware smoke test to synchronize platform view rendering. It introduces an ObservableTextView that triggers an onDraw method channel callback when painted, allowing the Dart side to await this callback and wait only 1 frame rather than a fixed 3 frames. Review feedback suggests using mapKeys for a more idiomatic Kotlin map transformation and storing the posted Runnable as a member variable to safely remove it on disposal, preventing potential race conditions.

gemini-code-assist

Code Review

This pull request updates the Android hardware smoke test to improve synchronization between native platform views and the Dart framework. It introduces an 'ObservableTextView' in Kotlin that overrides 'onDraw' to trigger a method channel callback, allowing the Dart app to wait for the native view to finish painting before proceeding. The 'goldens.dart' file was updated to use this callback for better timing, and the 'MainActivity' was modified to register the new view factory with this callback mechanism. No review comments were provided for this pull request.

gmackall

lgtm aside from removing onCreated from AndroidPlatformView if it is indeed unused now

gmackall · 2026-07-10T18:14:42Z

-      kPlatformViewTextureLayerTest => AndroidPlatformView(
+      kPlatformViewTextureLayerTest => const AndroidPlatformView(
        mode: PlatformViewMode.textureLayer,
-        onCreated: onPlatformViewCreated,


I think this is all of the onCreated uses in AndroidPlatformView (inside dev/integration_tests/android_hardware_smoke_test/lib/platform_view.dart) right? Should we remove the parameter if it's unused now?

whoops forgot to submit the comment before leaving review, this is what I was referring to

Good catch, done in d854cb3

…ngine caching.

auto-submit · 2026-07-10T21:27:09Z

autosubmit label was removed for flutter/flutter/189151, because - The status or check suite Dashboard Checks has failed. Please fix the issues identified (or deflake) before re-applying this label.

andywolff · 2026-07-10T21:54:01Z

I reran dashboard checks flakes and they passed, so I'm adding autosubmit label back

flutter/flutter@f7b66f3...cf9e8af 2026-07-12 [email protected] Flip from deprecated strict analysis modes to lint rules (flutter/flutter#187692) 2026-07-12 [email protected] Roll Skia from 6ecffccd32d5 to 8bf65996caba (5 revisions) (flutter/flutter#189333) 2026-07-11 [email protected] Roll Fuchsia Linux SDK from czpzDg9ABY2oKLAOY... to vhIlDkWIy21IrlB9E... (flutter/flutter#189309) 2026-07-11 [email protected] iOS: clean up swiftc.py after migration to target triples (flutter/flutter#189240) 2026-07-10 [email protected] Increase number of 'Mac tool_integration_tests' subshards from 5 to 10 (flutter/flutter#189040) 2026-07-10 [email protected] Fix PopupWindowControllerLinux missing WindowControllerLinux implementation (flutter/flutter#189189) 2026-07-10 [email protected] [android_hardware_smoke_test] Synchronize platform view compositing (flutter/flutter#189151) 2026-07-10 [email protected] UberSDF thin roundrect handling (flutter/flutter#189224) 2026-07-10 [email protected] Roll Skia from ab3a7b98c94d to 6ecffccd32d5 (15 revisions) (flutter/flutter#189270) 2026-07-10 [email protected] [skwasm][canvaskit] Honor Paint.filterQuality in Canvas.drawAtlas (flutter/flutter#186108) 2026-07-10 [email protected] Android_hardware_smoke_test: Cache flutter engine when running vulkan backend instrumented tests (flutter/flutter#189026) 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

Synchronize platform view compositing

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Replace the hardcoded 3-frame wait in platform view tests with a native draw event listener to prevent intermittent black screenshot failures.

github-actions Bot added the a: text input Entering text in a text field or keyboard related problems label Jul 8, 2026

andywolff added the CICD Run CI/CD label Jul 8, 2026

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Comment thread ...e_test/android/app/src/main/kotlin/com/example/android_hardware_smoke_test/NativeTextView.kt Outdated

Comment thread ...e_test/android/app/src/main/kotlin/com/example/android_hardware_smoke_test/NativeTextView.kt

andywolff added 2 commits July 8, 2026 13:29

review feedback

93514a8

Merge remote-tracking branch 'upstream/main' into sync_composition

73d62fc

andywolff marked this pull request as ready for review July 9, 2026 17:12

andywolff requested a review from flar July 9, 2026 17:12

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andywolff removed the request for review from flar July 10, 2026 17:28

jmagman added the platform-android Android applications specifically label Jul 10, 2026

jmagman requested a review from gmackall July 10, 2026 17:33

gmackall previously approved these changes Jul 10, 2026

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gmackall reviewed Jul 10, 2026

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andywolff added 2 commits July 10, 2026 13:13

clean up unused onCreated parameter

d854cb3

Merge upstream. Resolves one conflict in MainActivity.kt related to e…

92bc666

…ngine caching.

andywolff dismissed gmackall’s stale review via 92bc666 July 10, 2026 20:25

github-actions Bot removed the platform-android Android applications specifically label Jul 10, 2026

andywolff requested a review from gmackall July 10, 2026 20:29

gmackall approved these changes Jul 10, 2026

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andywolff added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 10, 2026

auto-submit Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Jul 10, 2026

andywolff added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 10, 2026

auto-submit Bot added this pull request to the merge queue Jul 10, 2026

Merged via the queue into flutter:master with commit b8690a4 Jul 10, 2026
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flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Jul 10, 2026

andywolff mentioned this pull request Jul 22, 2026

Linux_android_emu_vulkan_stable android_hardware_smoke_vulkan_tests is 2.00% flaky #189843

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[android_hardware_smoke_test] Synchronize platform view compositing#189151

[android_hardware_smoke_test] Synchronize platform view compositing#189151
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