fix: adjust scrollable size assertion with tolerance #171426

Zuckjet · 2025-07-01T09:20:08Z

The original issue highlights two separate bugs:

When Flutter calculates Widgets, there might be floating-point precision issues. For example, the calculation result may show _dragTargetRelatedToScrollOrigin.size.height as 64.00000000000003. Therefore, I introduced a very small tolerance to address this.
When there's a size scaling effect on the ReorderableListView, such as an influence from Transform.scale, the method for calculating the drag target becomes incorrect.

Pre-launch Checklist

I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
I read the [Tree Hygiene] wiki page, which explains my responsibilities.
I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
I signed the [CLA].
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is [test-exempt].
I followed the [breaking change policy] and added [Data Driven Fixes] where supported.
All existing and new tests are passing.

flutter-dashboard · 2025-07-01T09:20:10Z

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.

Piinks

Hey @Zuckjet welcome! Thank you for contributing.
Apologies this was missed in our regular triage meetings, happy to help move this forward.

Piinks · 2025-07-28T21:57:09Z

packages/flutter/lib/src/widgets/scrollable_helpers.dart

+      transform,
+      _dragTargetRelatedToScrollOrigin,
+    );
+    const double tolerance = 1e-10;


Can you use the predefined precisionErrorTolerance instead? :)

Piinks · 2025-07-28T22:09:02Z

packages/flutter/test/widgets/scrollable_helpers_test.dart

      }
    },
    variant: KeySimulatorTransitModeVariant.all(),
  );


Could you also add a test that verifies the reported issue with Column+Flexible works asa expected?

Resolves assertion errors when scrollable widgets are inside transformed parents (Transform.scale) or complex layouts (Column/Flexible). Issues fixed: - Inconsistent coordinate systems in size comparison - Floating-point precision errors from matrix transformations Changes: - Transform drag target to global coordinates before assertion - Add precision tolerance (1e-10) for floating-point accuracy - Add tests for Transform.scale and ReorderableListView scenarios Ensures auto-scrolling works correctly in scaled or complex layouts.

Piinks

This LGTM! Thank you!

Renzo-Olivares

LGTM, thank you for the contribution!

…er/flutter#171426)

Roll Flutter from c3279caa127d to 871849e4b6bf (56 revisions) flutter/flutter@c3279ca...871849e 2025-08-01 [email protected] Roll Dart SDK from 6832e04cf2f9 to 6e1bb159c860 (8 revisions) (flutter/flutter#173119) 2025-08-01 [email protected] Add `--profile-startup` flag to `flutter run` (flutter/flutter#172990) 2025-08-01 [email protected] Add `side` to `RadioThemeData` (flutter/flutter#171945) 2025-08-01 [email protected] Update GCA instructions (flutter/flutter#173001) 2025-08-01 [email protected] [engine] Null aware elements clean-ups (flutter/flutter#173075) 2025-08-01 [email protected] Roll Packages from db6988d to f0645d8 (3 revisions) (flutter/flutter#173111) 2025-08-01 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Reland licenses cpp switch 3 (#173063)" (flutter/flutter#173113) 2025-08-01 [email protected] Update embedder API CODEOWNERS (flutter/flutter#173081) 2025-08-01 [email protected] Move android_obfuscate_test from devicelab into tools integration.shard (flutter/flutter#169798) 2025-08-01 [email protected] [A11y] RangeSlider should have 2 focus node (flutter/flutter#172729) 2025-07-31 [email protected] Upload the linux arm64 embedder to cloud buckets. (flutter/flutter#173068) 2025-07-31 [email protected] Reland licenses cpp switch 3 (flutter/flutter#173063) 2025-07-31 [email protected] [ Tool ] Mark IOOverrides subclasses as `final` (flutter/flutter#173078) 2025-07-31 [email protected] [macOS] Remove duplicate object initialization (flutter/flutter#171767) 2025-07-31 [email protected] Redistribute Android test owners (flutter/flutter#172886) 2025-07-31 [email protected] Avoid negatives in the styleguide.md (flutter/flutter#172917) 2025-07-31 [email protected] Roll Skia from 42e3bed42110 to 49e39cd3cf18 (7 revisions) (flutter/flutter#173069) 2025-07-31 [email protected] Fix the issue where calling showOnScreen on a sliver after a pinned child in SliverMainAxisGroup does not reveal it. (flutter/flutter#171339) 2025-07-31 [email protected] Improve assertion message in `EdgeInsetsDirectional.resolve` (flutter/flutter#172099) 2025-07-31 [email protected] licenses_cpp: Switched to lexically_relative for 2x speed boost. (flutter/flutter#173048) 2025-07-31 [email protected] Add dartvm to the dart_sdk_entitlement_config list. (flutter/flutter#173044) 2025-07-31 [email protected] [web] ClickDebouncer workaround for iOS Safari click behavior (flutter/flutter#172995) 2025-07-31 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Reland licenses cpp switch 2 (#172996)" (flutter/flutter#173059) 2025-07-31 [email protected] [web] Text editing test accepts both behaviors in Firefox (flutter/flutter#172767) 2025-07-31 [email protected] Reland licenses cpp switch 2 (flutter/flutter#172996) 2025-07-31 [email protected] Roll Packages from d914120 to db6988d (2 revisions) (flutter/flutter#173039) 2025-07-31 [email protected] Add a SliverList code sample (flutter/flutter#172986) 2025-07-31 [email protected] fix: adjust scrollable size assertion with tolerance (flutter/flutter#171426) 2025-07-31 [email protected] impeller: Shrink `Command` 40 bytes (flutter/flutter#173004) 2025-07-31 [email protected] [web] Remove outdated comment about HTML renderer (flutter/flutter#172877) 2025-07-31 [email protected] Roll Skia from ff4da49305c5 to 42e3bed42110 (1 revision) (flutter/flutter#173038) 2025-07-31 [email protected] Roll Skia from 7d468a4868cb to ff4da49305c5 (3 revisions) (flutter/flutter#173028) 2025-07-31 [email protected] Roll Skia from 951277895c86 to 7d468a4868cb (1 revision) (flutter/flutter#173027) 2025-07-31 [email protected] Manual roll of Dart from 14ea8d342149 to 6832e04cf2f9 (flutter/flutter#173015) 2025-07-31 [email protected] Roll Skia from 8bdf4cdcf4ed to 951277895c86 (2 revisions) (flutter/flutter#173022) 2025-07-31 [email protected] Roll Fuchsia Linux SDK from bQVQlLssTxxLjoDU0... to xo_bqOoFuBKFmgKxn... (flutter/flutter#173021) 2025-07-31 [email protected] feat: Add `cursorHeight` to `DropdownMenu` (flutter/flutter#172615) 2025-07-31 [email protected] Roll Skia from a3347cee2d73 to 8bdf4cdcf4ed (3 revisions) (flutter/flutter#173013) 2025-07-31 [email protected] [ Widget Preview ] Add `--web-server` support (flutter/flutter#172978) 2025-07-30 [email protected] Bump customer tests for zulip fix 2 (flutter/flutter#173003) 2025-07-30 [email protected] Migrate to null aware elements - Part 4 (flutter/flutter#172322) 2025-07-30 [email protected] Marks Linux linux_feature_flags_test to be unflaky (flutter/flutter#172629) 2025-07-30 [email protected] [ Widget Previews ] Add support for `MultiPreview`s (flutter/flutter#172852) 2025-07-30 [email protected] Made licenses_cpp simpatico with google licenses (flutter/flutter#172991) 2025-07-30 [email protected] Roll Skia from d579722d65c6 to a3347cee2d73 (6 revisions) (flutter/flutter#172989) 2025-07-30 [email protected] Migrate to null aware elements - Part 5 (flutter/flutter#172418) ...

…lutter into add-non-uniform-table-border * 'add-non-uniform-table-border' of github.com:korca0220/flutter: (185 commits) Refactor `distinctVisibleOuterColors` -> private method Refactor Modify docs and method name Refactor Remove comments Refactor Modify docs and method parameters Feat Add tests Feat Add to non-uniform TableBorder - Add method for check outerUniform - Add internal helper method Add dartvm to the dart_sdk_entitlement_config list. (flutter#173044) [web] ClickDebouncer workaround for iOS Safari click behavior (flutter#172995) Reverts "Reland licenses cpp switch 2 (flutter#172996)" (flutter#173059) [web] Text editing test accepts both behaviors in Firefox (flutter#172767) Reland licenses cpp switch 2 (flutter#172996) Roll Packages from d914120 to db6988d (2 revisions) (flutter#173039) Add a SliverList code sample (flutter#172986) fix: adjust scrollable size assertion with tolerance (flutter#171426) impeller: Shrink `Command` 40 bytes (flutter#173004) [web] Remove outdated comment about HTML renderer (flutter#172877) Roll Skia from ff4da49305c5 to 42e3bed42110 (1 revision) (flutter#173038) Roll Skia from 7d468a4868cb to ff4da49305c5 (3 revisions) (flutter#173028) Roll Skia from 951277895c86 to 7d468a4868cb (1 revision) (flutter#173027) Manual roll of Dart from 14ea8d342149 to 6832e04cf2f9 (flutter#173015) ... # Conflicts: # packages/flutter/lib/src/rendering/table_border.dart # packages/flutter/test/rendering/table_border_test.dart

Fixes: flutter#136331 The original issue highlights two separate bugs: 1. When Flutter calculates Widgets, there might be floating-point precision issues. For example, the calculation result may show _dragTargetRelatedToScrollOrigin.size.height as 64.00000000000003. Therefore, I introduced a very small tolerance to address this. 2. When there's a size scaling effect on the ReorderableListView, such as an influence from Transform.scale, the method for calculating the drag target becomes incorrect. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [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. - [ ] 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.

…er/flutter#171426)

Fixes: flutter#136331 The original issue highlights two separate bugs: 1. When Flutter calculates Widgets, there might be floating-point precision issues. For example, the calculation result may show _dragTargetRelatedToScrollOrigin.size.height as 64.00000000000003. Therefore, I introduced a very small tolerance to address this. 2. When there's a size scaling effect on the ReorderableListView, such as an influence from Transform.scale, the method for calculating the drag target becomes incorrect. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [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. - [ ] 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.

github-actions bot added framework flutter/packages/flutter repository. See also f: labels. f: scrolling Viewports, list views, slivers, etc. labels Jul 1, 2025

Zuckjet force-pushed the fix/scrollable branch from 4a888cf to 6876ce8 Compare July 2, 2025 06:07

Piinks self-requested a review July 28, 2025 21:56

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Zuckjet force-pushed the fix/scrollable branch from 6876ce8 to 75044b7 Compare July 29, 2025 02:28

Zuckjet force-pushed the fix/scrollable branch from 75044b7 to 8903ba4 Compare July 29, 2025 03:18

Zuckjet requested a review from Piinks July 29, 2025 20:06

Piinks approved these changes Jul 30, 2025

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