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@mdebbar mdebbar commented Dec 8, 2025

Fixes #175074

There was an implicit expectation in the resizing code: When the virtual keyboard is up on mobile, the view's physicalSize remains fixed, and any resizes (presumably caused by the virtual keyboard itself) should be considered as viewInsets.

This expectation was broken inadvertently by my PR: #172493


The sequence of events that lead to the reported issue:

  1. View's physical size is calculated based on window size.
  2. Text editing starts, virtual keyboard comes up.
  3. View's physical size remains unchanged, and the difference caused by the keyboard is reported as view insets to the framework.
  4. (so far so good).
  5. When resizeToAvoidBottomInset is true, the framework will re-render its content to fit the available size.
  6. The new render call comes with a new size that's basically physical height - bottom inset.
  7. The engine takes that new size and applies it to the DOM.
  8. (now the view's DOM element has been resized incorrectly).
  9. ...
  10. Eventually, this leads to the new insets being calculated incorrectly resulting in negative insets which cause the framework to throw.

The fix involves the following:

  1. Respect the expectation mentioned above: when the keyboard is up, view's physical size should remain unchanged.
  2. If we ever end up with negative insets, catch it earlier in the engine so it's easier to debug the root cause.
  3. New regression test.

@github-actions github-actions bot added engine flutter/engine related. See also e: labels. platform-web Web applications specifically labels Dec 8, 2025
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Code Review

This pull request addresses a regression on Android web where resizeToAvoidBottomInset was not functioning correctly when the virtual keyboard is displayed. The fix ensures that the view's physicalSize is not updated by framework-initiated resizes while the keyboard is active, preserving the correct layout behavior. The changes include renaming methods for clarity, such as _didResize to _handleBrowserResize, and introducing a new getter _shouldPreservePhysicalSizeOnResize to encapsulate the logic. Additionally, an assertion has been added to detect negative viewInsets early, improving debuggability. A new regression test is also included to verify the fix. The changes are logical and well-implemented. My review includes a few suggestions to align the code with Effective Dart style guidelines.

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LGTM

@mdebbar mdebbar added the autosubmit Merge PR when tree becomes green via auto submit App label Dec 15, 2025
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Merged via the queue into flutter:master with commit 34bb652 Dec 15, 2025
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@flutter-dashboard flutter-dashboard bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Dec 15, 2025
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Roll Flutter from 6e1aa82 to d81baab (47 revisions)

flutter/flutter@6e1aa82...d81baab

2025-12-16 68449066+zijiehe-google-com@users.noreply.github.com Revert "chore: linux fuchsia tests are flaking" (flutter/flutter#179897)
2025-12-15 planetmarshall@users.noreply.github.com add default-linux-sysroot to gn frontend args (flutter/flutter#179303)
2025-12-15 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#179751)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from 783ce2077e46 to 6903a4e65c3f (2 revisions) (flutter/flutter#179903)
2025-12-15 adilhanney@disroot.org Add `Adwaita Sans` as a font fallback on Linux (flutter/flutter#179144)
2025-12-15 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Unmodified android sdk bundle (#179647)" (flutter/flutter#179904)
2025-12-15 robert.ancell@canonical.com Update window settings as they change rather than the more outdated "Apply" pattern. (flutter/flutter#179861)
2025-12-15 49699333+dependabot[bot]@users.noreply.github.com Bump dessant/lock-threads from 5.0.1 to 6.0.0 in the all-github-actions group (flutter/flutter#179901)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from 9decbd4c216b to 783ce2077e46 (2 revisions) (flutter/flutter#179896)
2025-12-15 34871572+gmackall@users.noreply.github.com Unmodified android sdk bundle (flutter/flutter#179647)
2025-12-15 mdebbar@google.com [web] Fix `resizeToAvoidBottomInset` on Android web (flutter/flutter#179581)
2025-12-15 iliyazelenkog@gmail.com Suppress deprecation warning for AChoreographer_postFrameCallback (flutter/flutter#178580)
2025-12-15 planetmarshall@users.noreply.github.com remove unnecessary virtual destructor from VertexDescriptor (flutter/flutter#178682)
2025-12-15 engine-flutter-autoroll@skia.org Roll Dart SDK from b245f6022727 to 20d114f951db (1 revision) (flutter/flutter#179893)
2025-12-15 jason-simmons@users.noreply.github.com [Impeller] Delete GLES framebuffer objects only on the thread where they were created (flutter/flutter#179768)
2025-12-15 jason-simmons@users.noreply.github.com [Impeller] Convert paths in ImpellerC command line flags to std::filesystem::path objects (flutter/flutter#179717)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from 5e1ff611b36b to 9decbd4c216b (2 revisions) (flutter/flutter#179890)
2025-12-15 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from DtfDWAx6t_CsD2e1W... to 433KtmJvbMyaDMJvD... (flutter/flutter#179889)
2025-12-15 116356835+AbdeMohlbi@users.noreply.github.com Remove unnecessary unboxing in `FlutterLoader.java‎` (flutter/flutter#179869)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from f04f8ca3b284 to 5e1ff611b36b (1 revision) (flutter/flutter#179882)
2025-12-15 engine-flutter-autoroll@skia.org Roll Packages from 0ac7a03 to 2cd921c (1 revision) (flutter/flutter#179885)
2025-12-15 bkonyi@google.com [ Widget Preview ] Pass DTD URI as a constant in a generated file (flutter/flutter#179821)
2025-12-15 116356835+AbdeMohlbi@users.noreply.github.com Bump minSdk to `24` in `engine` (flutter/flutter#175508)
2025-12-15 engine-flutter-autoroll@skia.org Roll Dart SDK from bca8bb37d95f to b245f6022727 (1 revision) (flutter/flutter#179879)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from eb1347d18957 to f04f8ca3b284 (1 revision) (flutter/flutter#179876)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from 41bcfb848b13 to eb1347d18957 (1 revision) (flutter/flutter#179871)
2025-12-15 engine-flutter-autoroll@skia.org Roll Skia from d194c3b7a9a9 to 41bcfb848b13 (6 revisions) (flutter/flutter#179866)
2025-12-14 robert.ancell@canonical.com Remove obsolete windowing channel (flutter/flutter#179718)
2025-12-14 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from SCLq31whvg8nJvuYE... to DtfDWAx6t_CsD2e1W... (flutter/flutter#179856)
2025-12-14 engine-flutter-autoroll@skia.org Roll Skia from 5d98ce0af031 to d194c3b7a9a9 (1 revision) (flutter/flutter#179854)
2025-12-13 engine-flutter-autoroll@skia.org Roll Skia from f9b242d9a365 to 5d98ce0af031 (1 revision) (flutter/flutter#179843)
2025-12-13 engine-flutter-autoroll@skia.org Roll Skia from abe90c72cf56 to f9b242d9a365 (1 revision) (flutter/flutter#179838)
2025-12-13 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from fppT9ZrwbFx7iYrIh... to SCLq31whvg8nJvuYE... (flutter/flutter#179836)
2025-12-13 engine-flutter-autoroll@skia.org Roll Dart SDK from 34654f2a3baa to bca8bb37d95f (1 revision) (flutter/flutter#179835)
2025-12-13 engine-flutter-autoroll@skia.org Roll Skia from 9e7c893bb593 to abe90c72cf56 (1 revision) (flutter/flutter#179830)
2025-12-13 engine-flutter-autoroll@skia.org Roll Dart SDK from f105c2168574 to 34654f2a3baa (1 revision) (flutter/flutter#179823)
2025-12-13 97480502+b-luk@users.noreply.github.com Add FilterQuality parameter to FragmentShader.setImageSampler (flutter/flutter#179760)
2025-12-13 evanwall@buffalo.edu Add profiling counts to pipeline uses (flutter/flutter#179374)
2025-12-13 engine-flutter-autoroll@skia.org Roll Skia from edf52cb27f29 to 9e7c893bb593 (3 revisions) (flutter/flutter#179819)
2025-12-12 jacksongardner@google.com Update Skwasm to engine style guidelines. (flutter/flutter#179756)
2025-12-12 engine-flutter-autoroll@skia.org Roll Dart SDK from 9a65db770758 to f105c2168574 (5 revisions) (flutter/flutter#179814)
2025-12-12 engine-flutter-autoroll@skia.org Roll Skia from f23b00a407a4 to edf52cb27f29 (5 revisions) (flutter/flutter#179807)
2025-12-12 97480502+b-luk@users.noreply.github.com Use depth buffer to implement geometry overdraw protection (flutter/flutter#179426)
2025-12-12 nshahan@google.com [flutter_tool] Force UTF-8 character set for dev (flutter/flutter#179419)
2025-12-12 engine-flutter-autoroll@skia.org Roll Skia from e66816c3645e to f23b00a407a4 (2 revisions) (flutter/flutter#179798)
2025-12-12 30870216+gaaclarke@users.noreply.github.com Implements decodeImageFromPixelsSync (flutter/flutter#179519)
...
@mdebbar mdebbar added the cp: stable cherry pick this pull request to stable release candidate branch label Jan 5, 2026
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Failed to create CP due to merge conflicts.
You will need to create the PR manually. See the cherrypick wiki for more info.

mdebbar added a commit to mdebbar/flutter that referenced this pull request Jan 5, 2026
Fixes flutter#175074

There was an implicit expectation in the resizing code: When the virtual
keyboard is up on mobile, the view's `physicalSize` remains fixed, and
any resizes (presumably caused by the virtual keyboard itself) should be
considered as `viewInsets`.

This expectation was broken inadvertently by my PR:
flutter#172493

<hr>

The sequence of events that lead to the reported issue:

1. View's physical size is calculated based on window size.
2. Text editing starts, virtual keyboard comes up.
3. View's physical size remains unchanged, and the difference caused by
the keyboard is reported as view insets to the framework.
4. (so far so good).
5. When `resizeToAvoidBottomInset` is true, the framework will re-render
its content to fit the available size.
6. The new render call comes with a new size that's basically `physical
height - bottom inset`.
7. The engine takes that new size and applies it to the DOM.
8.  (now the view's DOM element has been resized incorrectly).
9. ...
10. Eventually, this leads to the new insets being calculated
incorrectly resulting in negative insets which cause the framework to
throw.

<hr>

The fix involves the following:
1. Respect the expectation mentioned above: when the keyboard is up,
view's physical size should remain unchanged.
2. *_If_* we ever end up with negative insets, catch it earlier in the
engine so it's easier to debug the root cause.
3. New regression test.
auto-submit bot pushed a commit that referenced this pull request Jan 6, 2026
) (#180535)

Manual CP of the original PR: #179581

The "cherry-pick template" linked in https://github.com/flutter/flutter/wiki/Flutter-Cherrypick-Process/e7b042dd481d4ac66477fb281b6e626e8dba8a4e seems to be broken, so I copied the template from previous CP. 

### Issue Link:

#175074

### Impact Description:

All Android users are affected.

### Changelog Description:

When the virtual keyboard is closed, the area behind it remains blank and the app only draws in the area that used to be above the keyboard.

### Workaround:
None

### Risk:
What is the risk level of this cherry-pick?

### Test Coverage:
Are you confident that your fix is well-tested by automated tests?
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[Android Web] resizeToAvoidBottomInset broken on Android. Keyboard breaks layout.

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