[web] Cancel touch pointers WebKit abandons mid-gesture by flutter-zl · Pull Request #189608 · flutter/flutter

flutter-zl · 2026-07-16T19:13:34Z

Problem
On iOS 27, WebKit stops dispatching pointer events for a touch it promotes to a native gesture, such as dragging the caret in a text field, and delivers neither pointerup nor pointercancel. The framework is left holding a pointer that never lifts, which wedges BaseTapAndDragGestureRecognizer so every later tap is silently dropped: the field never regains focus and the keyboard never returns. Affects every iOS 27 browser, since they all run WebKit; iOS 26 is unaffected.

Fix
_PointerAdapter tracks which touch devices are down and, on touchend and touchcancel, cancels any the browser no longer lists in touches. Gated to iOSWebKit.

Demo
Before: https://flutter-demo-47-before.web.app
After: https://flutter-demo-47-after.web.app

Repro steps:
type in the field, long-press the caret and drag it, lift, then tap the field.
Before, the field is permanently dead after a few tries.
After, it recovers.

gemini-code-assist

Code Review

This pull request implements a safety mechanism for iOS WebKit to handle abandoned touch pointers that fail to dispatch 'pointerup' or 'pointercancel' events. It introduces a tracking set for active touch devices and a reconciliation method that identifies and cancels stale pointers by comparing them against the browser's 'touches' list. The changes include updates to 'dom.dart' for touch list access, 'pointer_binding.dart' for tracking and cancellation logic, and comprehensive regression tests in 'pointer_binding_test.dart'. The reviewer suggested improving the robustness of the tests by explicitly asserting both 'cancel' and 'remove' events.

Renzo-Olivares · 2026-07-20T22:48:09Z

  void _removePointerIfUnhoverable(DomPointerEvent event) {
    if (event.pointerType == 'touch') {
      _sanitizers.remove(event.pointerId);
+      _downTouchDevices.remove(_getPointerId(event));


Should getPointerId(event) just be event.pointerId like the line above?

Thinking about it more maybe the line above should become _sanitizers.remove(_getPointerId(event)).

Good catch. updated.

Renzo-Olivares · 2026-07-21T18:44:07Z

+
+    // The abandoned touch is reconciled while debouncing is active. Its cancel
+    // must bypass the queue and reach the framework immediately.
+    rootElement.dispatchEvent(_createTouchEvent('touchend', <int>[3], remaining: <int>[300]));


I don't think we define a touch for device 300 in this test.

Maybe the above event

tappable.dispatchEvent(context.primaryDown(clientX: 300, clientY: 300));

should be changed, defining a device id and making it a touch event.

tappable.dispatchEvent( context.multiTouchDown(const <_TouchDetails>[ _TouchDetails(pointer: 5, clientX: 300, clientY: 300), ]).single, );

and this line can become

rootElement.dispatchEvent(_createTouchEvent('touchend', <int>[3], remaining: <int>[5]));

Good catch. updated.

Renzo-Olivares · 2026-07-21T18:51:27Z

+  /// For synthetic events that must not be queued or dropped by an in-progress
+  /// debounce, such as cancels that repair a pointer the browser abandoned.
+  void sendImmediately(List<ui.PointerData> data) {
+    _sendToFramework(null, data);


Should we flush the events currently in the queue during debouncing here before forwarding to framework?

In the debouncing case, if there is a down event queued and we immediately dispatch the cancel/touchend event to the framework, then the queued down event may come after that and put the framework in a stuck state again.

Good catch. updated.

Renzo-Olivares

Overall the approach looks good to me, just had a few small comments.

Renzo-Olivares

LGTM, thanks for the fix!

auto-submit · 2026-07-23T22:43:03Z

autosubmit label was removed for flutter/flutter/189608, because - The status or check suite Dashboard Checks has failed. Please fix the issues identified (or deflake) before re-applying this label.

flutter/flutter@b65f4d9...e292197 2026-07-25 [email protected] Roll Skia from 2c014dc494f1 to 62442d6cf0ec (1 revision) (flutter/flutter#190022) 2026-07-25 [email protected] Roll Skia from d8d20eef4dbd to 2c014dc494f1 (1 revision) (flutter/flutter#190020) 2026-07-25 [email protected] [Impeller] Add 2D texture array support (kTexture2DArray) (flutter/flutter#188778) 2026-07-24 [email protected] Bumped Engine AGP Dependencies to 9.1.0 for 3.50 (flutter/flutter#189417) 2026-07-24 [email protected] Roll Dart SDK from 153abd9a8296 to 28e63ac22d8d (2 revisions) (flutter/flutter#190013) 2026-07-24 [email protected] ci: add mac verify binaries workflow (flutter/flutter#190010) 2026-07-24 [email protected] Roll Skia from f2f9b52fe1ee to d8d20eef4dbd (21 revisions) (flutter/flutter#190011) 2026-07-24 [email protected] fix(ci): quote labels to fix yaml mapping error (flutter/flutter#190002) 2026-07-24 [email protected] Update contributing guidelines for commit message format (flutter/flutter#189922) 2026-07-24 [email protected] Migrate a11y_assessments to uiscene (flutter/flutter#189960) 2026-07-24 [email protected] docs(contributing): add git worktree and rebase workflow guide (flutter/flutter#189992) 2026-07-24 [email protected] Roll Dart SDK from e3fc57eae9eb to 153abd9a8296 (3 revisions) (flutter/flutter#189987) 2026-07-24 [email protected] Rename RegularWindow* to Window* in the windowing API + rename sizedToContent to shrinkWrap in the windowing API (flutter/flutter#189363) 2026-07-24 [email protected] Remove ancient `tools:tools` dep from `android_sdk` bundle (flutter/flutter#189962) 2026-07-24 [email protected] Reduce the number of gtest-parallel workers when running Impeller tests on Mac Minis used by CI (flutter/flutter#189813) 2026-07-24 [email protected] Roll Packages from 8260a1e to 6969329 (21 revisions) (flutter/flutter#189983) 2026-07-24 [email protected] Roll Fuchsia Linux SDK from 9org0yL3yZkp80x5S... to Cdb1RGKCqpcz9z4cl... (flutter/flutter#189975) 2026-07-24 [email protected] Roll Skia from 6e9c4687c001 to f2f9b52fe1ee (3 revisions) (flutter/flutter#189959) 2026-07-24 [email protected] [web] Cancel touch pointers WebKit abandons mid-gesture (flutter/flutter#189608) 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 [email protected],[email protected] 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 pull request cherry-picks #189608 into the beta release branch (flutter-3.47-candidate.0) so the fix ships in the next stable release. ### Issue Link: #188781 ### Impact Description: P0 regression. On iOS 27, which affects every browser since they all run WebKit, a text field in a Flutter web app can become permanently unresponsive after a common gesture. When the user long-press-drags the selection caret and lifts, WebKit abandons the touch without delivering `pointerup` or `pointercancel`, leaving the framework holding a pointer that never lifts. This wedges the tap-and-drag gesture recognizer, so every later tap is silently dropped: the field never regains focus and the keyboard never returns, and the user can no longer type. It breaks text input in shipping production web apps. iOS 26 is unaffected. ### Changelog Description: [flutter/188781] When dragging the text selection caret on iOS 27 web browsers, text fields could become permanently unresponsive to taps and never regain focus; they now recover. ### Workaround: No in-app workaround. Reloading the page temporarily restores the field, but it breaks again the next time the gesture occurs. ### Risk: The change is small and strictly gated to iOS WebKit. It only cancels touch pointers the browser has already dropped from its `touches` list, so it cannot affect other platforms or normal pointer handling. ### Test Coverage: The fix adds 341 lines of engine unit tests in `pointer_binding_test.dart` covering the touch-cancel logic. ### Validation Steps: 1. Open a Flutter web app containing a TextField on an iOS 27 device, any browser. 2. Tap the field to focus it and type some text. 3. Long-press the selection caret, drag it, then lift your finger. 4. Tap the field again, and repeat a few times. 5. Before the fix the field becomes permanently dead: taps do nothing, no focus, no keyboard. After the fix the field keeps responding and recovers. Demo before: https://flutter-demo-47-before.web.app Demo after: https://flutter-demo-47-after.web.app

flutteractionsbot · 2026-09-03T14:26:52Z

Failed to create CP due to merge conflicts.
You will need to create the PR manually. See the cherrypick wiki for more info.

[web] Cancel touch pointers WebKit abandons mid-gesture

65de854

github-actions Bot added engine flutter/engine related. See also e: labels. platform-web Web applications specifically team-web Owned by Web platform team labels Jul 16, 2026

flutter-zl added the CICD Run CI/CD label Jul 16, 2026

flutter-zl marked this pull request as ready for review July 16, 2026 19:15

gemini-code-assist Bot reviewed Jul 16, 2026

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Comment thread engine/src/flutter/lib/web_ui/test/engine/pointer_binding_test.dart

[web] Assert the remove event in the abandoned touch test

223fbc2

LongCatIsLooong requested a review from Renzo-Olivares July 16, 2026 20:16

flutter-zl added 3 commits July 16, 2026 15:18

[web] Skip touch tests where TouchEvent cannot be constructed

d857342

Merge branch 'master' into issue_188781_fix

154ab6b

Merge branch 'master' into issue_188781_fix

61087f7

Renzo-Olivares reviewed Jul 21, 2026

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flutter-zl added 2 commits July 21, 2026 23:33

[web] Flush debounced pointers before the repair cancel

ce317ec

Merge branch 'master' into issue_188781_fix

c65c1e5

flutter-zl requested a review from Renzo-Olivares July 22, 2026 19:04

Merge branch 'master' into issue_188781_fix

db51515

Renzo-Olivares approved these changes Jul 23, 2026

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flutter-zl added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 23, 2026

Merge branch 'master' into issue_188781_fix

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github-merge-queue Bot removed this pull request from the merge queue due to no response for status checks Jul 23, 2026

flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Jul 23, 2026

Merge branch 'master' into issue_188781_fix

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flutter-zl added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 23, 2026

auto-submit Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Jul 23, 2026

Merge branch 'master' into issue_188781_fix

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flutter-zl added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 24, 2026

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Merged via the queue into flutter:master with commit b4f7989 Jul 24, 2026
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Piinks mentioned this pull request Jul 24, 2026

Flutter Notable Commits - 2026 #181433

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Roll Flutter from b65f4d9bc3fe to e2921977d4cc (19 revisions) flutter/packages#12287

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feat(web): support --web-content-hash for entrypoint files #190153

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This was referenced Jul 29, 2026

[beta] [web] Cancel touch pointers WebKit abandons mid-gesture #190231

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[web] iOS 27: TextField cursor sticks when dragging the caret after text is selected #190242

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mdebbar added the cp: stable cherry pick this pull request to stable release candidate branch label Sep 3, 2026

mdebbar removed the cp: stable cherry pick this pull request to stable release candidate branch label Sep 3, 2026

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flutter-zl commented Jul 16, 2026

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