[Impeller] Fix morphology filter asymmetric dilation/erosion#184913
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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.
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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.
flar
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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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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
…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
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:


after:
Golden test generated image:

Fixes: #184072
Pre-launch Checklist
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