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[Impeller] Fix morphology filter asymmetric dilation/erosion#184913

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arcashka:fix-dilation-asymetry
Apr 17, 2026
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[Impeller] Fix morphology filter asymmetric dilation/erosion#184913
auto-submit[bot] merged 1 commit into
flutter:masterfrom
arcashka:fix-dilation-asymetry

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@arcashka

@arcashka arcashka commented Apr 11, 2026

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This is the recreation of #184073, see the reasoning for this in #184073 (review)

The render target size was truncated via ISize(coverage.GetSize()),
which drops fractional pixels on the right/bottom edges. Fixed by
using std::ceil(), preventing asymmetric dilation coverage.

before:
image
after:
image

Golden test generated image:
image

Fixes: #184072

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The render target size was truncated via ISize(coverage.GetSize()),
which drops fractional pixels on the right/bottom edges. Fixed by
using std::ceil(), preventing asymmetric dilation/erosion coverage.
@github-actions github-actions Bot added engine flutter/engine related. See also e: labels. e: impeller Impeller rendering backend issues and features requests labels Apr 11, 2026

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Code Review

This pull request updates the morphology filter implementation to use ceiling dimensions for render targets, ensuring correct behavior when dealing with fractional coverage. It also adds a new golden test for fractional dilation and a dedicated unit test suite for morphology filters. The review feedback suggests improving the readability of the newly added tests by removing redundant conditional checks that follow terminal assertions.

@gaaclarke gaaclarke requested review from flar and walley892 April 13, 2026 18:03
@flar flar added the CICD Run CI/CD label Apr 13, 2026

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LGTM!

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Thanks @walley892 I didn't realize this was hung up on waiting for an approval so it could proceed with tests. Hopefully it can go in soon...

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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 #184913 at sha 7de2019

@flutter-dashboard flutter-dashboard Bot added the will affect goldens Changes to golden files label Apr 16, 2026
@flar flar added the autosubmit Merge PR when tree becomes green via auto submit App label Apr 17, 2026
@auto-submit auto-submit Bot added this pull request to the merge queue Apr 17, 2026
Merged via the queue into flutter:master with commit 67dec44 Apr 17, 2026
203 checks passed
@flutter-dashboard flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Apr 17, 2026
engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 17, 2026
auto-submit Bot pushed a commit to flutter/packages that referenced this pull request Apr 17, 2026
flutter/flutter@31f1802...8e8a194

2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (#184643)" (flutter/flutter#185203)
2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (#185192)" (flutter/flutter#185199)
2026-04-17 chris@bracken.jp [iOS] Migrate FlutterLaunchEngine to Swift (flutter/flutter#185151)
2026-04-17 116356835+AbdeMohlbi@users.noreply.github.com Remove unused `FlutterRunArguments.java` file  (flutter/flutter#184160)
2026-04-17 engine-flutter-autoroll@skia.org Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (flutter/flutter#185192)
2026-04-17 pewpewstol@gmail.com [Impeller] Fix morphology filter asymmetric dilation/erosion (flutter/flutter#184913)
2026-04-17 nate.w5687@gmail.com `AnimationStyle` methods (flutter/flutter#182333)
2026-04-17 karan@solvejet.net Fix _scheduleSystemFontsUpdate assertion during non-idle scheduler phase (flutter/flutter#184332)
2026-04-17 154381524+flutteractionsbot@users.noreply.github.com Revert "Unpin sdk package dependencies" (flutter/flutter#185186)
2026-04-16 116356835+AbdeMohlbi@users.noreply.github.com Clarify why the `child` is nullable in `AnimatedTransitionBuilder` (flutter/flutter#182995)
2026-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from IdBT8fSMYrYSip65j... to di3JdYrdE9OFu8Iyl... (flutter/flutter#185173)
2026-04-16 1063596+reidbaker@users.noreply.github.com Add dart_skills_lint to dev/tool with test and update readme instructions for new skills authors (flutter/flutter#185033)
2026-04-16 flar@google.com [Impeller] Provide std::optional getter for stroke property (flutter/flutter#185112)
2026-04-16 katelovett@google.com Validate itemExtent with geometry in RenderSliverFixedExtentBoxAdaptor (flutter/flutter#185159)
2026-04-16 152433210+mozammal-hossain@users.noreply.github.com [iOS] Clarify provisioning profile error instructions (flutter/flutter#184051)
2026-04-16 bkonyi@google.com [Widget Preview] Fix flaky integration test timeout during flutter clean (flutter/flutter#184991)
2026-04-16 engine-flutter-autoroll@skia.org Roll Dart SDK from fbddcbe0cd96 to 7c2564c18770 (2 revisions) (flutter/flutter#185143)
2026-04-16 sigurdm@google.com Unpin sdk package dependencies (flutter/flutter#184821)
2026-04-16 68919043+Istiak-Ahmed78@users.noreply.github.com Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (flutter/flutter#184643)
2026-04-16 engine-flutter-autoroll@skia.org Roll Skia from 391cdbe3ffe9 to d8415c5d7b91 (2 revisions) (flutter/flutter#185141)
2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185166)
2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Revert "Move widget_preview_scaffold into pub workspace" (flutter/flutter#185164)

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 boetger@google.com,stuartmorgan@google.com 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
creatorpiyush pushed a commit to creatorpiyush/packages that referenced this pull request Jun 10, 2026
…r#11523)

flutter/flutter@31f1802...8e8a194

2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (#184643)" (flutter/flutter#185203)
2026-04-17 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (#185192)" (flutter/flutter#185199)
2026-04-17 chris@bracken.jp [iOS] Migrate FlutterLaunchEngine to Swift (flutter/flutter#185151)
2026-04-17 116356835+AbdeMohlbi@users.noreply.github.com Remove unused `FlutterRunArguments.java` file  (flutter/flutter#184160)
2026-04-17 engine-flutter-autoroll@skia.org Roll Fuchsia Test Scripts from R2EllDf4DgBXVNuiN... to dQ4PjIJB5kZFU8Y32... (flutter/flutter#185192)
2026-04-17 pewpewstol@gmail.com [Impeller] Fix morphology filter asymmetric dilation/erosion (flutter/flutter#184913)
2026-04-17 nate.w5687@gmail.com `AnimationStyle` methods (flutter/flutter#182333)
2026-04-17 karan@solvejet.net Fix _scheduleSystemFontsUpdate assertion during non-idle scheduler phase (flutter/flutter#184332)
2026-04-17 154381524+flutteractionsbot@users.noreply.github.com Revert "Unpin sdk package dependencies" (flutter/flutter#185186)
2026-04-16 116356835+AbdeMohlbi@users.noreply.github.com Clarify why the `child` is nullable in `AnimatedTransitionBuilder` (flutter/flutter#182995)
2026-04-16 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from IdBT8fSMYrYSip65j... to di3JdYrdE9OFu8Iyl... (flutter/flutter#185173)
2026-04-16 1063596+reidbaker@users.noreply.github.com Add dart_skills_lint to dev/tool with test and update readme instructions for new skills authors (flutter/flutter#185033)
2026-04-16 flar@google.com [Impeller] Provide std::optional getter for stroke property (flutter/flutter#185112)
2026-04-16 katelovett@google.com Validate itemExtent with geometry in RenderSliverFixedExtentBoxAdaptor (flutter/flutter#185159)
2026-04-16 152433210+mozammal-hossain@users.noreply.github.com [iOS] Clarify provisioning profile error instructions (flutter/flutter#184051)
2026-04-16 bkonyi@google.com [Widget Preview] Fix flaky integration test timeout during flutter clean (flutter/flutter#184991)
2026-04-16 engine-flutter-autoroll@skia.org Roll Dart SDK from fbddcbe0cd96 to 7c2564c18770 (2 revisions) (flutter/flutter#185143)
2026-04-16 sigurdm@google.com Unpin sdk package dependencies (flutter/flutter#184821)
2026-04-16 68919043+Istiak-Ahmed78@users.noreply.github.com Fix ImageInfo.isCloneOf to correctly compare scale values (fixes #184626) (flutter/flutter#184643)
2026-04-16 engine-flutter-autoroll@skia.org Roll Skia from 391cdbe3ffe9 to d8415c5d7b91 (2 revisions) (flutter/flutter#185141)
2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185166)
2026-04-16 154381524+flutteractionsbot@users.noreply.github.com Revert "Move widget_preview_scaffold into pub workspace" (flutter/flutter#185164)

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 boetger@google.com,stuartmorgan@google.com 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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ImageFilter.dilate produces asymmetric results on Android

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