Fixes animation glitch into bottom sheet by Mairramer · Pull Request #183303 · flutter/flutter

Mairramer · 2026-03-06T13:03:49Z

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.

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Note: The Flutter team is currently trialing the use of Gemini Code Assist for GitHub. 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.

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Code Review

This pull request addresses an animation glitch in the modal bottom sheet. The fix involves recalculating the animation curve in handleDragEnd based on the current animation progress when a drag gesture concludes, ensuring a smooth transition. A new widget test is also added to verify that the bottom sheet's position does not jump when a drag is released. However, the new test has a flaw in its implementation that needs to be addressed.

dkwingsmt

LGTM. Thank you!

dkwingsmt · 2026-03-13T02:49:43Z

The Google testing failure is a real assertion error of

  @override
  void didUpdateWidget(_ModalBottomSheet<T> oldWidget) {
    super.didUpdateWidget(oldWidget);
    assert(oldWidget.route == widget.route);

    assert(
      _curvedSheetAnimation.curve == (widget.animationStyle?.curve ?? _kModalBottomSheetCurve),
    );
    assert(
      _curvedSheetAnimation.reverseCurve ==
          (widget.animationStyle?.reverseCurve ?? _kModalBottomSheetCurve),
    );
    assert(_sheetAnimation.parent == _curvedSheetAnimation);  // This assertion failed.
  }

It seems reasonable since this PR updated _sheetAnimation.parent. However I'm concerned that this isn't caught by a unit test. Do you think you can come up with a unit test for this?

Mairramer · 2026-03-13T12:49:01Z

The Google testing failure is a real assertion error of

  @override
  void didUpdateWidget(_ModalBottomSheet<T> oldWidget) {
    super.didUpdateWidget(oldWidget);
    assert(oldWidget.route == widget.route);

    assert(
      _curvedSheetAnimation.curve == (widget.animationStyle?.curve ?? _kModalBottomSheetCurve),
    );
    assert(
      _curvedSheetAnimation.reverseCurve ==
          (widget.animationStyle?.reverseCurve ?? _kModalBottomSheetCurve),
    );
    assert(_sheetAnimation.parent == _curvedSheetAnimation);  // This assertion failed.
  }

It seems reasonable since this PR updated _sheetAnimation.parent. However I'm concerned that this isn't caught by a unit test. Do you think you can come up with a unit test for this?

I removed the assert, since it doesn’t make sense in this case. In the previous PR where I introduced these asserts, I wasn’t able to test, so I added a few that seemed reasonable to validate.

dkwingsmt

LGTM. Thank you for the quick fix!

…83303)

flutter/flutter@d117642...dd64978 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 2fb5fa71eb12 to f0a13e5efbad (2 revisions) (flutter/flutter#183830) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from ae3d36cb9e29 to 2fb5fa71eb12 (3 revisions) (flutter/flutter#183823) 2026-03-18 94012149+richardexfo@users.noreply.github.com Linux reuse sibling (flutter/flutter#183653) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 84a180a1fa80 to ae3d36cb9e29 (4 revisions) (flutter/flutter#183812) 2026-03-18 1961493+harryterkelsen@users.noreply.github.com fix(web): handle asynchronously disposed platform views (flutter/flutter#183666) 2026-03-17 87018443+mayanksharma9@users.noreply.github.com (Test cross-imports) Remove legacy Material import from sliver_constraints_test (flutter/flutter#183351) 2026-03-17 74057391+jhonathanqz@users.noreply.github.com Fix Android Studio pluginsPath when version is unknown (do not use 0.0) (flutter/flutter#182681) 2026-03-17 50643541+Mairramer@users.noreply.github.com Fixes animation glitch into bottom sheet (flutter/flutter#183303) 2026-03-17 ahmedsameha1@gmail.com Handle#6537 second grouped test (flutter/flutter#182529) 2026-03-17 ahmedsameha1@gmail.com Add a Clarification for the docs of suggestionsBuilder of SearchAnchor (flutter/flutter#183106) 2026-03-17 nate.w5687@gmail.com Remove obsolete null checks from style guide (flutter/flutter#181703) 2026-03-17 jason-simmons@users.noreply.github.com [Impeller] Do not delete the GL object in a HandleGLES if the handle has a cleanup callback (flutter/flutter#183561) 2026-03-17 jason-simmons@users.noreply.github.com Encode source file patches as UTF-8 in the code formatter script (flutter/flutter#183761) 2026-03-17 82673815+gktirkha@users.noreply.github.com Fix widget inspector control layout and add safe area regression test (flutter/flutter#180789) 2026-03-17 43054281+camsim99@users.noreply.github.com Reland "[Android] Add mechanism for setting Android engine flags via Android manifest (take 2)" (flutter/flutter#182522) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web): fix crash in Skwasm when transferring non-transferable texture sources (flutter/flutter#183799) 2026-03-17 engine-flutter-autoroll@skia.org Roll Skia from dba893a44d7a to 84a180a1fa80 (7 revisions) (flutter/flutter#183803) 2026-03-17 brunocorona.alcantar@gmail.com Framework: Improve DropdownButton selectedItemBuilder assertion (flutter/flutter#183732) 2026-03-17 brunocorona.alcantar@gmail.com Add mainAxisAlignment to NavigationRail (flutter/flutter#183514) 2026-03-17 34871572+gmackall@users.noreply.github.com Update android triage process to not look at unassigned p1s every week (flutter/flutter#183805) 2026-03-17 30870216+gaaclarke@users.noreply.github.com Adds macos impeller new gallery transition perf test. (flutter/flutter#183802) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): move prepareToDraw after raster to improve concurrency and stability (flutter/flutter#183791) 2026-03-17 rmacnak@google.com [build] Generate debug info for assembly. (flutter/flutter#183425) 2026-03-17 mdebbar@google.com [web] Fix occasional failure to find Chrome tab (flutter/flutter#183737) 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#11281) flutter/flutter@d117642...dd64978 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 2fb5fa71eb12 to f0a13e5efbad (2 revisions) (flutter/flutter#183830) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from ae3d36cb9e29 to 2fb5fa71eb12 (3 revisions) (flutter/flutter#183823) 2026-03-18 94012149+richardexfo@users.noreply.github.com Linux reuse sibling (flutter/flutter#183653) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 84a180a1fa80 to ae3d36cb9e29 (4 revisions) (flutter/flutter#183812) 2026-03-18 1961493+harryterkelsen@users.noreply.github.com fix(web): handle asynchronously disposed platform views (flutter/flutter#183666) 2026-03-17 87018443+mayanksharma9@users.noreply.github.com (Test cross-imports) Remove legacy Material import from sliver_constraints_test (flutter/flutter#183351) 2026-03-17 74057391+jhonathanqz@users.noreply.github.com Fix Android Studio pluginsPath when version is unknown (do not use 0.0) (flutter/flutter#182681) 2026-03-17 50643541+Mairramer@users.noreply.github.com Fixes animation glitch into bottom sheet (flutter/flutter#183303) 2026-03-17 ahmedsameha1@gmail.com Handle#6537 second grouped test (flutter/flutter#182529) 2026-03-17 ahmedsameha1@gmail.com Add a Clarification for the docs of suggestionsBuilder of SearchAnchor (flutter/flutter#183106) 2026-03-17 nate.w5687@gmail.com Remove obsolete null checks from style guide (flutter/flutter#181703) 2026-03-17 jason-simmons@users.noreply.github.com [Impeller] Do not delete the GL object in a HandleGLES if the handle has a cleanup callback (flutter/flutter#183561) 2026-03-17 jason-simmons@users.noreply.github.com Encode source file patches as UTF-8 in the code formatter script (flutter/flutter#183761) 2026-03-17 82673815+gktirkha@users.noreply.github.com Fix widget inspector control layout and add safe area regression test (flutter/flutter#180789) 2026-03-17 43054281+camsim99@users.noreply.github.com Reland "[Android] Add mechanism for setting Android engine flags via Android manifest (take 2)" (flutter/flutter#182522) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web): fix crash in Skwasm when transferring non-transferable texture sources (flutter/flutter#183799) 2026-03-17 engine-flutter-autoroll@skia.org Roll Skia from dba893a44d7a to 84a180a1fa80 (7 revisions) (flutter/flutter#183803) 2026-03-17 brunocorona.alcantar@gmail.com Framework: Improve DropdownButton selectedItemBuilder assertion (flutter/flutter#183732) 2026-03-17 brunocorona.alcantar@gmail.com Add mainAxisAlignment to NavigationRail (flutter/flutter#183514) 2026-03-17 34871572+gmackall@users.noreply.github.com Update android triage process to not look at unassigned p1s every week (flutter/flutter#183805) 2026-03-17 30870216+gaaclarke@users.noreply.github.com Adds macos impeller new gallery transition perf test. (flutter/flutter#183802) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): move prepareToDraw after raster to improve concurrency and stability (flutter/flutter#183791) 2026-03-17 rmacnak@google.com [build] Generate debug info for assembly. (flutter/flutter#183425) 2026-03-17 mdebbar@google.com [web] Fix occasional failure to find Chrome tab (flutter/flutter#183737) 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

Fixes flutter#183299 ## 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]. - [ ] 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 [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 --------- Co-authored-by: Victor Sanni <victorsanniay@gmail.com>

…r#11281) flutter/flutter@d117642...dd64978 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 2fb5fa71eb12 to f0a13e5efbad (2 revisions) (flutter/flutter#183830) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from ae3d36cb9e29 to 2fb5fa71eb12 (3 revisions) (flutter/flutter#183823) 2026-03-18 94012149+richardexfo@users.noreply.github.com Linux reuse sibling (flutter/flutter#183653) 2026-03-18 engine-flutter-autoroll@skia.org Roll Skia from 84a180a1fa80 to ae3d36cb9e29 (4 revisions) (flutter/flutter#183812) 2026-03-18 1961493+harryterkelsen@users.noreply.github.com fix(web): handle asynchronously disposed platform views (flutter/flutter#183666) 2026-03-17 87018443+mayanksharma9@users.noreply.github.com (Test cross-imports) Remove legacy Material import from sliver_constraints_test (flutter/flutter#183351) 2026-03-17 74057391+jhonathanqz@users.noreply.github.com Fix Android Studio pluginsPath when version is unknown (do not use 0.0) (flutter/flutter#182681) 2026-03-17 50643541+Mairramer@users.noreply.github.com Fixes animation glitch into bottom sheet (flutter/flutter#183303) 2026-03-17 ahmedsameha1@gmail.com Handle#6537 second grouped test (flutter/flutter#182529) 2026-03-17 ahmedsameha1@gmail.com Add a Clarification for the docs of suggestionsBuilder of SearchAnchor (flutter/flutter#183106) 2026-03-17 nate.w5687@gmail.com Remove obsolete null checks from style guide (flutter/flutter#181703) 2026-03-17 jason-simmons@users.noreply.github.com [Impeller] Do not delete the GL object in a HandleGLES if the handle has a cleanup callback (flutter/flutter#183561) 2026-03-17 jason-simmons@users.noreply.github.com Encode source file patches as UTF-8 in the code formatter script (flutter/flutter#183761) 2026-03-17 82673815+gktirkha@users.noreply.github.com Fix widget inspector control layout and add safe area regression test (flutter/flutter#180789) 2026-03-17 43054281+camsim99@users.noreply.github.com Reland "[Android] Add mechanism for setting Android engine flags via Android manifest (take 2)" (flutter/flutter#182522) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web): fix crash in Skwasm when transferring non-transferable texture sources (flutter/flutter#183799) 2026-03-17 engine-flutter-autoroll@skia.org Roll Skia from dba893a44d7a to 84a180a1fa80 (7 revisions) (flutter/flutter#183803) 2026-03-17 brunocorona.alcantar@gmail.com Framework: Improve DropdownButton selectedItemBuilder assertion (flutter/flutter#183732) 2026-03-17 brunocorona.alcantar@gmail.com Add mainAxisAlignment to NavigationRail (flutter/flutter#183514) 2026-03-17 34871572+gmackall@users.noreply.github.com Update android triage process to not look at unassigned p1s every week (flutter/flutter#183805) 2026-03-17 30870216+gaaclarke@users.noreply.github.com Adds macos impeller new gallery transition perf test. (flutter/flutter#183802) 2026-03-17 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): move prepareToDraw after raster to improve concurrency and stability (flutter/flutter#183791) 2026-03-17 rmacnak@google.com [build] Generate debug info for assembly. (flutter/flutter#183425) 2026-03-17 mdebbar@google.com [web] Fix occasional failure to find Chrome tab (flutter/flutter#183737) 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

fix: fixes animation glitch into bottom sheet

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github-actions Bot added framework flutter/packages/flutter repository. See also f: labels. f: material design flutter/packages/flutter/material repository. labels Mar 6, 2026

test: add regression test

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improve test

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Merge branch 'master' into fix/animation-glitch-bottom-sheet

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Merge branch 'master' into fix/animation-glitch-bottom-sheet

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dkwingsmt self-requested a review March 11, 2026 18:24

remove assert

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Merge branch 'master' into fix/animation-glitch-bottom-sheet

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