Fixes translated bounded blurs by gaaclarke · Pull Request #191615 · flutter/flutter

gaaclarke · 2026-08-24T21:37:39Z

before

impeller_Play_AiksTest_CanRenderBoundedBlurWithTranslation_Metal

after

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gemini-code-assist

Code Review

This pull request introduces a new unit test for rendering bounded blurs with translation and updates Canvas::SaveLayer to pass the full transform instead of just the basis to SetEffectTransform. Additionally, it updates BorderMaskBlurFilterContents to use TransformDirection when scaling the sigma vector. However, passing the full transform (including translation) will cause regressions in other FilterContents subclasses (such as GaussianBlurFilterContents and DirectionalGaussianBlurFilterContents) that still multiply effect_transform directly with a vector, incorrectly applying the translation to the blur sigma/radius. These subclasses must also be updated to use TransformDirection to prevent this issue.

flutter-dashboard · 2026-08-24T21:46:01Z

This pull request has been changed to a draft. The currently pending flutter-gold status will not be able to resolve until a new commit is pushed or the change is marked ready for review again.

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flutter-dashboard · 2026-08-24T23:13:23Z

CI had a failure that stopped further tests from running. We need to investigate to determine the root cause.

SHA at time of execution: a3cac69.

Possible causes:

Configuration Changes: The .ci.yaml file might have been modified between the creation of this pull request and the start of this test run. This can lead to ci yaml validation errors.
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A blank commit, or merging to head, will be required to resume running CI for this PR.

Error Details:

FormatException: ERROR: Mac_arm64_ios integration_test_test_ios is a new builder added. it needs to be marked bringup: true
If ci.yaml wasn't changed, try `git fetch upstream && git merge upstream/master`

Stack trace:

#0      CiYaml._validate (package:cocoon_service/src/model/ci_yaml/ci_yaml.dart:395:7)
#1      new CiYaml (package:cocoon_service/src/model/ci_yaml/ci_yaml.dart:128:7)
#2      new CiYamlSet (package:cocoon_service/src/model/ci_yaml/ci_yaml.dart:48:23)
#3      CiYamlFetcher._getCiYaml (package:cocoon_service/src/service/scheduler/ci_yaml_fetcher.dart:124:12)
<asynchronous suspension>
#4      Scheduler.getPresubmitTargets (package:cocoon_service/src/service/scheduler.dart:1088:20)
<asynchronous suspension>
#5      Scheduler._getTestsForStage (package:cocoon_service/src/service/scheduler.dart:1404:14)
<asynchronous suspension>
#6      Scheduler._runCiTestingStage (package:cocoon_service/src/service/scheduler.dart:1445:30)
<asynchronous suspension>
#7      Scheduler.proceedToCiTestingStage (package:cocoon_service/src/service/scheduler.dart:1554:7)
<asynchronous suspension>
#8      Scheduler._closeSuccessfulEngineBuildStage (package:cocoon_service/src/service/scheduler.dart:1351:5)
<asynchronous suspension>
#9      Scheduler.processCheckRunCompleted (package:cocoon_service/src/service/scheduler.dart:1277:11)
<asynchronous suspension>
#10     PresubmitSubscription._processBuild (package:cocoon_service/src/request_handlers/presubmit_subscription.dart:226:7)
<asynchronous suspension>
#11     PresubmitSubscription.post (package:cocoon_service/src/request_handlers/presubmit_subscription.dart:119:5)
<asynchronous suspension>
#12     RequestHandler.service (package:cocoon_service/src/request_handling/request_handler.dart:42:20)
<asynchronous suspension>
#13     SubscriptionHandler.service (package:cocoon_service/src/request_handling/subscription_handler.dart:134:5)
<asynchronous suspension>
#14     createServer.<anonymous closure> (package:cocoon_service/server.dart:462:7)
<asynchronous suspension>
#15     main.<anonymous closure>.<anonymous closure> (file:///app/app_dart/bin/gae_server.dart:192:9)
<asynchronous suspension>

(adds test)

gemini-code-assist

Code Review

This pull request modifies Impeller's backdrop filter processing to use the full transform instead of only its basis, and updates BorderMaskBlurFilterContents to compute the sigma vector using TransformDirection. Additionally, a unit test is added to verify bounded blurs under translation, scale, and rotation. Feedback suggests taking the absolute value of the transformed direction to prevent negative sigma values when the transform includes a negative scale.

gemini-code-assist · 2026-08-24T23:35:58Z

+  auto sigma = effect_transform.TransformDirection(
+      Vector2(sigma_x_.sigma, sigma_y_.sigma));


If the effect_transform contains a negative scale (which is common when mirroring or flipping widgets), TransformDirection will produce negative components for sigma. Negative sigma values can lead to rendering artifacts or undefined behavior in the blur shaders. Taking the absolute value of the transformed direction ensures the sigma remains non-negative.

Suggested change

auto sigma = effect_transform.TransformDirection(

Vector2(sigma_x_.sigma, sigma_y_.sigma));

auto sigma = effect_transform.TransformDirection(

Vector2(sigma_x_.sigma, sigma_y_.sigma)).Abs();

dkwingsmt

Wow, thank you! LGTM.

flutter-dashboard · 2026-08-25T01:44:15Z

Golden file changes have been found for this pull request. Click here to view and triage (e.g. because this is an intentional change).

If you are still iterating on this change and are not ready to resolve the images on the Flutter Gold dashboard, consider marking this PR as a draft pull request above. You will still be able to view image results on the dashboard, commenting will be silenced, and the check will not try to resolve itself until marked ready for review.

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Changes reported for pull request #191615 at sha 6b5b15e

gaaclarke · 2026-08-25T16:24:00Z

It's not quite right yet. All the impeller golden tests passed, but I think I broke some magnifier tests. =T

gaaclarke · 2026-08-25T20:39:56Z

Okay, I had to tweak this to make it work. We just didn't have the correct information to translate the blur's bounds into the correct place. The effect transform stripped out the translation information, which we needed. I can't see an alternative other than providing that as an different matrix.

flutter-dashboard · 2026-08-25T22:31:44Z

Golden file changes are available for triage from new commit, Click here to view.

For more guidance, visit Writing a golden file test for package:flutter.

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Changes reported for pull request #191615 at sha f5f3bbb

gaaclarke · 2026-08-25T22:33:30Z

Goldens are looking good now. There were those 2 flakey goldens only which are driving me cuckoo

dkwingsmt

What a rabbit hole!

dkwingsmt · 2026-08-25T22:44:10Z

@@ -1886,6 +1886,8 @@ void Canvas::SaveLayer(const Paint& paint,
                  FilterInput::Make(std::move(input_texture)));
    backdrop_filter_contents->SetEffectTransform(


What about removing SetEffectTransform and delegate GetEffectTransform to GetLocalToPassTransform().Basis()?

I tried playing around with stuff like this. It seems in theory EffectTransform is just LocalToPassTransform.Basis(). It doesn't work that way though because you have to store the specific use case for backdrop filters. It doesn't work that way uniformly across all usages of the effect transform. I tried a couple of things and this was the cleanest I could think of.

gaaclarke · 2026-08-25T23:07:12Z

I've accepted the flakey golden failures for the following tests. I think we can maintain the broken goldens and the fixed goldens until the issue is fixed.

flakey goldens approved:

android_engine_test.opengles.fluttered_rendered_blue_rectangle
android_engine_test.opengles.platform_view_tap_color_change_initial

Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions) flutter/flutter@15d8908...e8dca90 2026-08-27 [email protected] Terminate existing process before launching with devicectl (flutter/flutter#191885) 2026-08-27 [email protected] Roll Fuchsia Linux SDK from qjOQi-zAgu_tADorh... to dDxH8G5cDBP602eyG... (flutter/flutter#191889) 2026-08-27 [email protected] [flutter_tools] Verify native assets tree-shaking during linking (flutter/flutter#191637) 2026-08-27 [email protected] Denylists b-series powervr from vulkan (flutter/flutter#191808) 2026-08-27 [email protected] Handle linear and radial gradients in UberSDF (flutter/flutter#190874) 2026-08-27 [email protected] Roll Packages from 740f093 to bd3cbc1 (7 revisions) (flutter/flutter#191886) 2026-08-27 [email protected] Disable more Windows tests that have been causing CI flakes (flutter/flutter#191822) 2026-08-27 [email protected] Roll Skia from d32721369bd8 to 82e972ea84b1 (2 revisions) (flutter/flutter#191880) 2026-08-27 [email protected] Roll Skia from 3640b8edd16c to d32721369bd8 (10 revisions) (flutter/flutter#191858) 2026-08-27 [email protected] Revert: [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191863) 2026-08-27 [email protected] Roll Fuchsia Test Scripts from 0iCv10IlKfiilEBOU... to 6SXRz6wsA2Zm_rAqP... (flutter/flutter#191852) 2026-08-27 [email protected] Roll pub packages (flutter/flutter#191851) 2026-08-27 [email protected] Refactor FormField build wrappers (flutter/flutter#185795) 2026-08-27 [email protected] Make ScrollPhysics reactive by introducing shouldUpdate (flutter/flutter#189664) 2026-08-27 [email protected] macOS: Fix crash on out-of-bounds text input ranges (flutter/flutter#191780) 2026-08-27 [email protected] Add HCPP feature flag, and turn it on by default in beta/master (flutter/flutter#190623) 2026-08-27 [email protected] [tool] Migrate CleanCommand to modular dependency injection (flutter/flutter#190742) 2026-08-26 [email protected] Update triage docs for ecosystem and codelab changes (flutter/flutter#191809) 2026-08-26 [email protected] [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191824) 2026-08-26 [email protected] [UIScene] Migrate dev/benchmarks/complex_layout to UIScene lifecycle (flutter/flutter#191619) 2026-08-26 [email protected] Add SliverAppBar showOnScreen semantics test coverage (flutter/flutter#190410) 2026-08-26 [email protected] Add prompt_suggestion icon to list of RTL mirroring icons. (flutter/flutter#191741) 2026-08-26 [email protected] Remove bringup for batch 3 (flutter/flutter#191750) 2026-08-26 [email protected] Roll Skia from b5465d7b0b77 to 3640b8edd16c (6 revisions) (flutter/flutter#191835) 2026-08-26 [email protected] Uiscene migrate custom channels views (flutter/flutter#191817) 2026-08-26 [email protected] Support --[no-]adb-log-filtering CLI option (flutter/flutter#187252) 2026-08-26 [email protected] Roll Dart SDK from cb8a4e1a0fbb to cb4c39d067f3 (2 revisions) (flutter/flutter#191825) 2026-08-26 [email protected] Fix `Navigator.pushNamed<T>()` type checking (flutter/flutter#188148) 2026-08-26 [email protected] Handle the case where a window doesn't have a title set (flutter/flutter#191767) 2026-08-26 [email protected] [Android] Remove old `InputType` constructor from embedding (flutter/flutter#191244) 2026-08-26 [email protected] Roll Skia from 244a6a0f8f92 to b5465d7b0b77 (19 revisions) (flutter/flutter#191810) 2026-08-26 [email protected] Tolerate floating-point rounding in paintImage centerSlice assertion (flutter/flutter#185789) 2026-08-26 [email protected] Fixes translated bounded blurs (flutter/flutter#191615) 2026-08-26 [email protected] Roll Fuchsia Linux SDK from MstTWE1RDOT-RnrtH... to qjOQi-zAgu_tADorh... (flutter/flutter#191769) 2026-08-26 [email protected] Lerp HSVColor and HSLColor hue along the shortest arc (flutter/flutter#191186) 2026-08-26 [email protected] Fix enum instances comparison to use `equality ==` since dart has the correct behavior now (flutter/flutter#191537) 2026-08-26 [email protected] Switches windows to opengles 3 (flutter/flutter#191516) 2026-08-26 [email protected] Roll Dart SDK from 7739e8602bc1 to cb8a4e1a0fbb (1 revision) (flutter/flutter#191784) 2026-08-26 [email protected] iOS,macOS: Check viewType before creating a platform view (flutter/flutter#191777) 2026-08-26 [email protected] Revert: [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191793) 2026-08-26 [email protected] refactor(flutter_tools): clean up dead unreferenced declarations (flutter/flutter#191163) 2026-08-26 [email protected] Roll Fuchsia GN SDK from a87CbQSWEjkPUK1ZY... to ZsxUUK2SfA-TrNvb8... (flutter/flutter#191763) 2026-08-26 [email protected] [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191732) 2026-08-25 [email protected] Remove legacy gen_defaults analyze checks (flutter/flutter#191629) 2026-08-25 [email protected] Refactors `try` to avoid `unawaited_return_in_try_block` case (flutter/flutter#191129) 2026-08-25 [email protected] Roll Dart SDK from 8996935d3d0a to 7739e8602bc1 (1 revision) (flutter/flutter#191754) ...

…r#12660) Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions) flutter/flutter@15d8908...e8dca90 2026-08-27 [email protected] Terminate existing process before launching with devicectl (flutter/flutter#191885) 2026-08-27 [email protected] Roll Fuchsia Linux SDK from qjOQi-zAgu_tADorh... to dDxH8G5cDBP602eyG... (flutter/flutter#191889) 2026-08-27 [email protected] [flutter_tools] Verify native assets tree-shaking during linking (flutter/flutter#191637) 2026-08-27 [email protected] Denylists b-series powervr from vulkan (flutter/flutter#191808) 2026-08-27 [email protected] Handle linear and radial gradients in UberSDF (flutter/flutter#190874) 2026-08-27 [email protected] Roll Packages from 740f093 to bd3cbc1 (7 revisions) (flutter/flutter#191886) 2026-08-27 [email protected] Disable more Windows tests that have been causing CI flakes (flutter/flutter#191822) 2026-08-27 [email protected] Roll Skia from d32721369bd8 to 82e972ea84b1 (2 revisions) (flutter/flutter#191880) 2026-08-27 [email protected] Roll Skia from 3640b8edd16c to d32721369bd8 (10 revisions) (flutter/flutter#191858) 2026-08-27 [email protected] Revert: [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191863) 2026-08-27 [email protected] Roll Fuchsia Test Scripts from 0iCv10IlKfiilEBOU... to 6SXRz6wsA2Zm_rAqP... (flutter/flutter#191852) 2026-08-27 [email protected] Roll pub packages (flutter/flutter#191851) 2026-08-27 [email protected] Refactor FormField build wrappers (flutter/flutter#185795) 2026-08-27 [email protected] Make ScrollPhysics reactive by introducing shouldUpdate (flutter/flutter#189664) 2026-08-27 [email protected] macOS: Fix crash on out-of-bounds text input ranges (flutter/flutter#191780) 2026-08-27 [email protected] Add HCPP feature flag, and turn it on by default in beta/master (flutter/flutter#190623) 2026-08-27 [email protected] [tool] Migrate CleanCommand to modular dependency injection (flutter/flutter#190742) 2026-08-26 [email protected] Update triage docs for ecosystem and codelab changes (flutter/flutter#191809) 2026-08-26 [email protected] [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191824) 2026-08-26 [email protected] [UIScene] Migrate dev/benchmarks/complex_layout to UIScene lifecycle (flutter/flutter#191619) 2026-08-26 [email protected] Add SliverAppBar showOnScreen semantics test coverage (flutter/flutter#190410) 2026-08-26 [email protected] Add prompt_suggestion icon to list of RTL mirroring icons. (flutter/flutter#191741) 2026-08-26 [email protected] Remove bringup for batch 3 (flutter/flutter#191750) 2026-08-26 [email protected] Roll Skia from b5465d7b0b77 to 3640b8edd16c (6 revisions) (flutter/flutter#191835) 2026-08-26 [email protected] Uiscene migrate custom channels views (flutter/flutter#191817) 2026-08-26 [email protected] Support --[no-]adb-log-filtering CLI option (flutter/flutter#187252) 2026-08-26 [email protected] Roll Dart SDK from cb8a4e1a0fbb to cb4c39d067f3 (2 revisions) (flutter/flutter#191825) 2026-08-26 [email protected] Fix `Navigator.pushNamed<T>()` type checking (flutter/flutter#188148) 2026-08-26 [email protected] Handle the case where a window doesn't have a title set (flutter/flutter#191767) 2026-08-26 [email protected] [Android] Remove old `InputType` constructor from embedding (flutter/flutter#191244) 2026-08-26 [email protected] Roll Skia from 244a6a0f8f92 to b5465d7b0b77 (19 revisions) (flutter/flutter#191810) 2026-08-26 [email protected] Tolerate floating-point rounding in paintImage centerSlice assertion (flutter/flutter#185789) 2026-08-26 [email protected] Fixes translated bounded blurs (flutter/flutter#191615) 2026-08-26 [email protected] Roll Fuchsia Linux SDK from MstTWE1RDOT-RnrtH... to qjOQi-zAgu_tADorh... (flutter/flutter#191769) 2026-08-26 [email protected] Lerp HSVColor and HSLColor hue along the shortest arc (flutter/flutter#191186) 2026-08-26 [email protected] Fix enum instances comparison to use `equality ==` since dart has the correct behavior now (flutter/flutter#191537) 2026-08-26 [email protected] Switches windows to opengles 3 (flutter/flutter#191516) 2026-08-26 [email protected] Roll Dart SDK from 7739e8602bc1 to cb8a4e1a0fbb (1 revision) (flutter/flutter#191784) 2026-08-26 [email protected] iOS,macOS: Check viewType before creating a platform view (flutter/flutter#191777) 2026-08-26 [email protected] Revert: [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191793) 2026-08-26 [email protected] refactor(flutter_tools): clean up dead unreferenced declarations (flutter/flutter#191163) 2026-08-26 [email protected] Roll Fuchsia GN SDK from a87CbQSWEjkPUK1ZY... to ZsxUUK2SfA-TrNvb8... (flutter/flutter#191763) 2026-08-26 [email protected] [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191732) 2026-08-25 [email protected] Remove legacy gen_defaults analyze checks (flutter/flutter#191629) 2026-08-25 [email protected] Refactors `try` to avoid `unawaited_return_in_try_block` case (flutter/flutter#191129) 2026-08-25 [email protected] Roll Dart SDK from 8996935d3d0a to 7739e8602bc1 (1 revision) (flutter/flutter#191754) ...

flutter-dashboard Bot added the CICD Run CI/CD label Aug 24, 2026

gaaclarke changed the title ~~Translated bounded blur~~ Fixes translated bounded blurs Aug 24, 2026

github-actions Bot added engine flutter/engine related. See also e: labels. e: impeller Impeller rendering backend issues and features requests labels Aug 24, 2026

gemini-code-assist Bot reviewed Aug 24, 2026

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Comment thread engine/src/flutter/impeller/display_list/canvas.cc

gaaclarke marked this pull request as draft August 24, 2026 21:40

gaaclarke added 2 commits August 24, 2026 16:15

Fixes translated bounded blurs

9fab26e

(adds test)

the fix

6b5b15e

gaaclarke force-pushed the translated-bounded-blur branch from a3cac69 to 6b5b15e Compare August 24, 2026 23:15

gaaclarke marked this pull request as ready for review August 24, 2026 23:35

gaaclarke requested a review from dkwingsmt August 24, 2026 23:35

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flutter-dashboard Bot added the will affect goldens Changes to golden files label Aug 25, 2026

gaaclarke added 2 commits August 25, 2026 13:37

adds magnification test

8f3230d

adds localtopass matrix

f5f3bbb

gaaclarke dismissed dkwingsmt’s stale review via f5f3bbb August 25, 2026 20:38

gaaclarke requested a review from dkwingsmt August 25, 2026 22:33

dkwingsmt approved these changes Aug 25, 2026

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gaaclarke added the autosubmit Merge PR when tree becomes green via auto submit App label Aug 25, 2026

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Merged via the queue into flutter:master with commit 6f1ed6c Aug 26, 2026
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flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Aug 26, 2026

justinmc mentioned this pull request Aug 28, 2026

Flutter Notable Commits - 2026 #181433

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dkwingsmt mentioned this pull request Aug 31, 2026

[impeller] FadeTransition wrapping CupertinoPopupSurface breaks appearance on Impeller #182066

Closed

		auto sigma = effect_transform.TransformDirection(
		Vector2(sigma_x_.sigma, sigma_y_.sigma));

		@@ -1886,6 +1886,8 @@ void Canvas::SaveLayer(const Paint& paint,
		FilterInput::Make(std::move(input_texture)));
		backdrop_filter_contents->SetEffectTransform(

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