For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath. by b-luk · Pull Request #184258 · flutter/flutter

b-luk · 2026-03-27T18:38:03Z

For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath.

From https://api.flutter.dev/flutter/painting/ShapeBorder/paintInterior.html:

On ShapeBorder subclasses whose preferPaintInterior method returns true, this should be faster than using Canvas.drawPath with the path provided by getOuterPath.

paintInterior is semantically equivalent to (i.e. renders the same pixels as) calling Canvas.drawPath with the same Paint and the Path returned from getOuterPath

Part of #183044

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…erior rather than drawing the path from getOuterPath.

gemini-code-assist

Code Review

This pull request updates the painting logic for several widgets, including Checkbox, Chip, InputDecorator, and Scrollbar, to utilize the preferPaintInterior and paintInterior methods of ShapeBorder. This allows for more efficient painting by using specific primitives like rounded rectangles or circles instead of generic paths when supported by the shape. Numerous tests were updated to reflect these changes in the painting commands. The review feedback suggests refactoring code in chip.dart and scrollbar.dart to use local variables for non-nullable types, thereby avoiding repeated null assertions.

gemini-code-assist · 2026-03-27T22:46:20Z

+        if (avatarBorder!.preferPaintInterior) {
+          avatarBorder!.paintInterior(context.canvas, avatarRect, darkenPaint);
+        } else {
+          final Path path = avatarBorder!.getOuterPath(avatarRect);
+          context.canvas.drawPath(path, darkenPaint);
+        }


To improve readability and avoid repeated null assertions (!), you could introduce a local variable for avatarBorder after the null check. This makes the code cleaner and safer.

final ShapeBorder localAvatarBorder = avatarBorder!; if (localAvatarBorder.preferPaintInterior) { localAvatarBorder.paintInterior(context.canvas, avatarRect, darkenPaint); } else { final Path path = localAvatarBorder.getOuterPath(avatarRect); context.canvas.drawPath(path, darkenPaint); }

gemini-code-assist · 2026-03-27T22:46:20Z

+      if (shape!.preferPaintInterior) {
+        shape!.paintInterior(canvas, _thumbRect!, _paintThumb);
+      } else {
+        final Path outerPath = shape!.getOuterPath(_thumbRect!);
+        canvas.drawPath(outerPath, _paintThumb);
+      }
      shape!.paint(canvas, _thumbRect!);


To improve readability and avoid repeated null assertions (!), you could introduce local variables for shape and _thumbRect. This makes the code cleaner and safer.

final ShapeBorder localShape = shape!; final Rect thumbRect = _thumbRect!; if (localShape.preferPaintInterior) { localShape.paintInterior(canvas, thumbRect, _paintThumb); } else { final Path outerPath = localShape.getOuterPath(thumbRect); canvas.drawPath(outerPath, _paintThumb); } localShape.paint(canvas, thumbRect);

gaaclarke

Oh nice. I was worried as I read through the PR about testing but looks like we had nice coverage to make sure we don't accidentally break this in the future. Thanks.

…e paintInterior rather than drawing the path from getOuterPath. (flutter/flutter#184258)

…erior rather than drawing the path from getOuterPath. (flutter#184258) For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath. From https://api.flutter.dev/flutter/painting/ShapeBorder/paintInterior.html: > On [ShapeBorder](https://api.flutter.dev/flutter/painting/ShapeBorder-class.html) subclasses whose [preferPaintInterior](https://api.flutter.dev/flutter/painting/ShapeBorder/preferPaintInterior.html) method returns true, this should be faster than using [Canvas.drawPath](https://api.flutter.dev/flutter/dart-ui/Canvas/drawPath.html) with the path provided by [getOuterPath](https://api.flutter.dev/flutter/painting/ShapeBorder/getOuterPath.html). > [paintInterior](https://api.flutter.dev/flutter/painting/ShapeBorder/paintInterior.html) is semantically equivalent to (i.e. renders the same pixels as) calling [Canvas.drawPath](https://api.flutter.dev/flutter/dart-ui/Canvas/drawPath.html) with the same [Paint](https://api.flutter.dev/flutter/dart-ui/Paint-class.html) and the [Path](https://api.flutter.dev/flutter/dart-ui/Path-class.html) returned from [getOuterPath](https://api.flutter.dev/flutter/painting/ShapeBorder/getOuterPath.html) Part of flutter#183044 ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

github-actions Bot added framework flutter/packages/flutter repository. See also f: labels. f: material design flutter/packages/flutter/material repository. f: scrolling Viewports, list views, slivers, etc. f: cupertino flutter/packages/flutter/cupertino repository labels Mar 27, 2026

For ShapeBorder instances that set preferPaintInterior, use paintIint…

fcae826

…erior rather than drawing the path from getOuterPath.

b-luk force-pushed the paintinterior branch from 8aca22f to fcae826 Compare March 27, 2026 18:44

b-luk added the CICD Run CI/CD label Mar 27, 2026

b-luk changed the title ~~For ShapeBorder instances that set preferPaintInterior, use paintInterior rather than drawing the path from getOuterPath.~~ For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath. Mar 27, 2026

github-actions Bot removed the CICD Run CI/CD label Mar 27, 2026

test fixes

082b185

b-luk force-pushed the paintinterior branch from 2e295b0 to 082b185 Compare March 27, 2026 21:53

b-luk added the CICD Run CI/CD label Mar 27, 2026

more test fixes

38bca21

github-actions Bot added d: api docs Issues with https://api.flutter.dev/ d: examples Sample code and demos and removed CICD Run CI/CD labels Mar 27, 2026

b-luk added the CICD Run CI/CD label Mar 27, 2026

b-luk marked this pull request as ready for review March 27, 2026 22:44

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b-luk requested a review from gaaclarke March 27, 2026 23:35

gaaclarke approved these changes Mar 27, 2026

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 1, 2026

bfe5141d8 For ShapeBorder instances with preferPaintInterior=true, us…

69f60fa

…e paintInterior rather than drawing the path from getOuterPath. (flutter/flutter#184258)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 1, 2026

bfe5141d8 For ShapeBorder instances with preferPaintInterior=true, us…

f63fa15

…e paintInterior rather than drawing the path from getOuterPath. (flutter/flutter#184258)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 1, 2026

bfe5141d8 For ShapeBorder instances with preferPaintInterior=true, us…

268be24

…e paintInterior rather than drawing the path from getOuterPath. (flutter/flutter#184258)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Apr 1, 2026

bfe5141d8 For ShapeBorder instances with preferPaintInterior=true, us…

11a7c51

…e paintInterior rather than drawing the path from getOuterPath. (flutter/flutter#184258)

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For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath.#184258

For ShapeBorder instances with preferPaintInterior=true, use paintInterior rather than drawing the path from getOuterPath.#184258
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b-luk commented Mar 27, 2026 •

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