web_ui: avoid crash for showPerformanceOverlay; log 'not supported' once #173518

muradhossin · 2025-08-10T16:32:42Z

On Flutter Web, calling MaterialApp(showPerformanceOverlay: true) reaches
SceneBuilder.addPerformanceOverlay, which previously threw UnimplementedError
and crashed apps. This change makes the method a no-op on Web and logs a one-time
warning:

"showPerformanceOverlay is not supported on Flutter Web. Use DevTools
Performance (Timeline) instead."

Rationale: Avoid crashes and guide developers to the supported tooling on Web.

Testing:

Relied on CI for web_ui builds and tests.
(Manual reproduction before fix) Enabling showPerformanceOverlay on Web produced
UnimplementedError from canvaskit/layer_scene_builder.dart.

…nce (fixes flutter#172405)

flutter-dashboard · 2025-08-10T16:32:46Z

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.

google-cla · 2025-08-10T16:32:47Z

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Code Review

This pull request effectively resolves a crash on Flutter Web when showPerformanceOverlay is enabled. Instead of throwing an UnimplementedError, the method now logs a helpful, one-time warning to the console guiding developers to the correct tools. The change is simple and correct. I've added one suggestion to improve code clarity by marking unused parameters according to Dart conventions.

engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart

mdebbar

Looks good, thanks for the contribution!

Would you mind adding a simple test that does something like this:

final LayerSceneBuilder sb = LayerSceneBuilder();
expect(
  () => sb.addPerformanceOverlay(0, ui.Rect.zero),
  returnsNormally,
);

engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart

mdebbar · 2025-08-21T15:30:21Z

Would you mind adding a simple test that does something like this:
final LayerSceneBuilder sb = LayerSceneBuilder();
expect(
  () => sb.addPerformanceOverlay(0, ui.Rect.zero),
  returnsNormally,
);

Bonus points if you also check for the warning message being printed 😃 Here's an example you could copy from:

flutter/engine/src/flutter/lib/web_ui/test/engine/profiler_test.dart

Lines 31 to 34 in 6ddbb81

    
           oldPrintWarning = printWarning; 
        
           printWarning = (String warning) { 
        
             warnings.add(warning); 
        
           };

engine/src/flutter/lib/web_ui/test/engine/performance_overlay_test.dart

engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart

…lay warning

…ormance-overlay

mdebbar · 2025-08-28T15:55:27Z

Sorry for the confusion. I didn't mean that you should move the file. The file has moved in master, so I wanted you to rebase to pick up the file move.

I fixed it and merged latest master into this PR.

mdebbar

The change looks good to me!

I think the test may fail until #174588 lands. Let's wait for that PR to land, and then let's update this PR and submit it.

…ormance-overlay

harryterkelsen

LGTM

auto-submit · 2025-08-28T19:43:55Z

autosubmit label was removed for flutter/flutter/173518, because - The status or check suite Windows windows_unopt has failed. Please fix the issues identified (or deflake) before re-applying this label.

auto-submit · 2025-08-28T21:46:43Z

autosubmit label was removed for flutter/flutter/173518, because - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label.

mdebbar · 2025-09-17T18:14:13Z

Waiting for #175392 to land.

auto-submit · 2025-09-24T18:35:01Z

autosubmit label was removed for flutter/flutter/173518, because - The status or check suite Linux linux_android_debug_engine_ddm has failed. Please fix the issues identified (or deflake) before re-applying this label.

auto-submit · 2025-09-24T21:03:00Z

autosubmit label was removed for flutter/flutter/173518, because - The status or check suite Mac mac_ios_engine has failed. Please fix the issues identified (or deflake) before re-applying this label.

auto-submit · 2025-09-24T22:48:29Z

autosubmit label was removed for flutter/flutter/173518, because - The status or check suite Linux linux_fuchsia_tests has failed. Please fix the issues identified (or deflake) before re-applying this label.

…pported' once (flutter/flutter#173518)

Roll Flutter from 4a042046a0f1 to b1a28bc065b0 (44 revisions) flutter/flutter@4a04204...b1a28bc 2025-09-25 [email protected] web_ui: avoid crash for showPerformanceOverlay; log 'not supported' once (flutter/flutter#173518) 2025-09-25 [email protected] Ignore upcoming `experimental_member_use` warnings. (flutter/flutter#175969) 2025-09-25 [email protected] Roll Skia from 753ce2221ce7 to 55436d87e414 (16 revisions) (flutter/flutter#176004) 2025-09-25 [email protected] Add google_fonts to team-framework triage guidelines (flutter/flutter#175675) 2025-09-25 [email protected] Add tests for InputDecoration borders (M3 and theme normalization) (flutter/flutter#175838) 2025-09-24 [email protected] Update Flutter's templates to use dot shorthands (flutter/flutter#175891) 2025-09-24 [email protected] In Gradle Flutter task, correctly replace '\ ' with ' '. (flutter/flutter#175815) 2025-09-24 [email protected] Cleans up navigator pop and remove logic (flutter/flutter#175612) 2025-09-24 [email protected] Fix docs in `EditableText` (flutter/flutter#175787) 2025-09-24 [email protected] Fixes SemanticsFlags.isLink mis-translated in dart ui ffi (flutter/flutter#175812) 2025-09-24 [email protected] Update AGP/Java/Gradle comparison when using analyze --suggestions (flutter/flutter#175808) 2025-09-24 [email protected] Fix SliverMainAxisGroup SliverEnsureSemantics support (flutter/flutter#175671) 2025-09-24 [email protected] Migrate to `WidgetStateColor` (flutter/flutter#175573) 2025-09-24 [email protected] Make sure that a FlexibleSpaceBar doesn't crash in 0x0 environment (flutter/flutter#175228) 2025-09-24 [email protected] Roll Fuchsia Test Scripts from BWj3yYC74ud58QhN0... to APSBP-sS-3FX69Ihf... (flutter/flutter#175944) 2025-09-24 [email protected] Make sure that a MaterialApp doesn't crash in 0x0 environment (flutter/flutter#173090) 2025-09-24 [email protected] feat(cupertino): Add selectableDayPredicate parameter to CupertinoDatePicker for selectable day control #171332 (flutter/flutter#171334) 2025-09-24 [email protected] Refactor `FlutterInjectorTest` to use lambdas/method reference (flutter/flutter#175777) 2025-09-24 [email protected] Replace curly braces with lambdas in `KeyEventChannelTest` (flutter/flutter#175729) 2025-09-24 [email protected] [ Widget Preview ] Fix filter by file on Windows (flutter/flutter#175783) 2025-09-24 [email protected] use lambda expressions /method reference to fix linter issue in `DartMessengerTest.java` (flutter/flutter#175733) 2025-09-24 [email protected] Roll Packages from 3413b65 to 117bf63 (9 revisions) (flutter/flutter#175935) 2025-09-24 [email protected] refactor code to use method reference and lambdas in `DartMessengerTest.java` (flutter/flutter#175731) 2025-09-24 [email protected] Simplify/fix ordering of asserts in `TextInputPluginTest` (flutter/flutter#175784) 2025-09-24 [email protected] Introduce a getter for `Project` to get `gradle-wrapper.properties` directly (flutter/flutter#175485) 2025-09-24 [email protected] Change the arguments order in `assertEquals` to fix linter issues (flutter/flutter#175719) 2025-09-24 [email protected] Broken link in NavigationRail documentation (flutter/flutter#175852) 2025-09-24 [email protected] Updates to flutter web triage links (flutter/flutter#175791) 2025-09-24 [email protected] Do not present textures in FlutterMetalLayer if the drawable size changed and the texture's size does not match the new drawable size (flutter/flutter#175450) 2025-09-24 [email protected] Remove comment about trailing commas from templates (flutter/flutter#175864) 2025-09-24 [email protected] Roll Skia from 1c1b19f2ffc3 to 753ce2221ce7 (4 revisions) (flutter/flutter#175909) 2025-09-24 [email protected] Roll Skia from 3191a822cf10 to 1c1b19f2ffc3 (2 revisions) (flutter/flutter#175896) 2025-09-24 [email protected] Roll Skia from cabeab8cb22c to 3191a822cf10 (14 revisions) (flutter/flutter#175894) 2025-09-24 [email protected] Roll Dart SDK from 14b4ced3022a to 899c7340cc4c (4 revisions) (flutter/flutter#175893) 2025-09-24 [email protected] Roll `package:analyzer` forward to `8.2.0`. (flutter/flutter#175849) 2025-09-24 [email protected] Make sure that a VerticalDivider doesn't crash at 0x0 environment (flutter/flutter#174761) 2025-09-24 [email protected] Make sure that Drawer & DrawerHeader don't crash in 0x0 environment (flutter/flutter#174772) 2025-09-24 [email protected] Add an assertion for the relationship between `Visibility.maintainState` and `Visibility.maintainFocusability` (flutter/flutter#175552) 2025-09-24 [email protected] fix: remove final class modifier on MenuController (flutter/flutter#174490) 2025-09-24 [email protected] fix: cupertino sheet broken example with programatic pop (flutter/flutter#175709) 2025-09-24 [email protected] [web] Fix assertion thrown when hot restarting during animation (flutter/flutter#175856) 2025-09-24 [email protected] Add non uniform TableBorder (flutter/flutter#175773) 2025-09-23 [email protected] fix small typo in test docs (flutter/flutter#175776) 2025-09-23 [email protected] Use `assertNull` to simplify code (flutter/flutter#175720) If this roll has caused a breakage, revert this CL and stop the roller ...

…pported' once (flutter/flutter#173518)

…nce (flutter#173518) Fixes flutter#172405 On Flutter Web, calling `MaterialApp(showPerformanceOverlay: true)` reaches `SceneBuilder.addPerformanceOverlay`, which previously threw `UnimplementedError` and crashed apps. This change makes the method a no-op on Web and logs a one-time warning: "showPerformanceOverlay is not supported on Flutter Web. Use DevTools Performance (Timeline) instead." Rationale: Avoid crashes and guide developers to the supported tooling on Web. Testing: - Relied on CI for web_ui builds and tests. - (Manual reproduction before fix) Enabling `showPerformanceOverlay` on Web produced UnimplementedError from `canvaskit/layer_scene_builder.dart`. --------- Co-authored-by: Mouad Debbar <[email protected]>

web_ui: avoid crash for showPerformanceOverlay; log 'not supported' o…

cd91caa

…nce (fixes flutter#172405)

github-actions bot added engine flutter/engine related. See also e: labels. platform-web Web applications specifically labels Aug 10, 2025

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mdebbar self-requested a review August 20, 2025 18:27

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web_ui: improve performance overlay warning and add tests

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muradhossin requested a review from mdebbar August 21, 2025 18:07

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refactor: reorganize layer scene builder and improve performance over…

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…lay warning

muradhossin requested a review from mdebbar August 28, 2025 15:27

mdebbar added 3 commits August 28, 2025 11:48

undo file move

2079e43

Merge remote-tracking branch 'upstream/master' into fix/web-noop-perf…

e2cbb9c

…ormance-overlay

dart format

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mdebbar approved these changes Aug 28, 2025

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mdebbar added 2 commits August 28, 2025 14:17

generalize test

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Merge remote-tracking branch 'upstream/master' into fix/web-noop-perf…

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…ormance-overlay

harryterkelsen approved these changes Aug 28, 2025

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Merge branch 'master' into fix/web-noop-performance-overlay

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Roll Flutter from 4a042046a0f1 to b1a28bc065b0 (44 revisions) flutter/packages#10077

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b1a28bc06 web_ui: avoid crash for showPerformanceOverlay; log 'not su…

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…pported' once (flutter/flutter#173518)

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b1a28bc06 web_ui: avoid crash for showPerformanceOverlay; log 'not su…

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…pported' once (flutter/flutter#173518)

web_ui: avoid crash for showPerformanceOverlay; log 'not supported' once #173518

web_ui: avoid crash for showPerformanceOverlay; log 'not supported' once #173518

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