[iOS] Preserve semantics parents after reparenting by AfzalivE · Pull Request #189686 · flutter/flutter

AfzalivE · 2026-07-18T07:43:20Z

Problem

Reordering a ReorderableListView on iOS could move VoiceOver focus to the upper-left corner of the screen. The affected items could no longer be focused at their visual positions.

During a reorder, semantics children move through temporary containers used by the drag overlay and drop animation. A child may already have been attached to its replacement SemanticsObject when its previous parent is updated or deallocated.

The previous parent unconditionally cleared the child's parent property. This overwrote the new parent relationship and disconnected the child from the native semantics hierarchy.

SemanticsObject calculates its global accessibility frame by walking this parent chain and composing each ancestor's transform. Once the chain was disconnected, the element retained only its local physical-pixel rectangle. On a 3x simulator, the expected frame:

{{0, 286}, {402, 56}}

became:

{{0, 0}, {134, 18.67}}

This accounts for both the missing translation and the frame being reduced by the device pixel ratio.

Fix

Only clear a child's parent when the SemanticsObject performing cleanup still owns that parent relationship:

child.parent == self

This guard is applied when:

A SemanticsObject is deallocated.
Its traversal-order children are replaced.
Its hit-test-order children are replaced.

A previous parent can now release its stale child references without detaching a child that has already moved under a replacement container. The complete ancestor transform remains available when calculating the native accessibility frame.

Testing

Added An iOS XCUITest that performs the default mobile long-press reorder gesture, verifies the resulting native semantic traversal order, and asserts that the reordered item retains the expected accessibility frame.

The integration app also includes a deterministic direct-drag fixture for exercising XCUITest drag synthesis.

Validation performed:

testReorderableListAccessibilityHierarchyUpdates passes with the locally built engine.
packages/flutter/test/widgets/reorderable_list_test.dart passes.
packages/flutter/test/material/reorderable_list_test.dart passes.
ios_test_flutter builds successfully.
Engine formatting and Dart analysis pass.

Pre-launch Checklist

Exercise the default mobile long-press reorder path and verify that the native iOS semantic hierarchy preserves the reordered item's frame. Issue: flutter#100946

Only detach a semantics child when the object being updated still owns its parent link. This prevents a removed reorderable-list container from clearing a child that has already moved into its replacement and losing the ancestor transform used for its accessibility frame. Issue: flutter#100946

Add a deterministic reorder target and native UI test for exercising drag interactions in the iOS platform-view integration app.

gemini-code-assist

Code Review

This pull request updates iOS semantics handling in SemanticsObject.mm to ensure that an old parent does not detach a child that has already been reparented, and adds corresponding unit and integration tests. The review feedback identifies that ReorderableListView.builder in both drag.dart and reorderable_list_semantics.dart incorrectly uses the non-existent parameter onReorderItem instead of onReorder.

cbracken · 2026-08-13T21:54:09Z

@LongCatIsLooong @LouiseHsu friendly ping for review.

LongCatIsLooong

LGTM. Thanks for contributing!

LongCatIsLooong · 2026-08-14T23:48:14Z

+class _DragScreenState extends State<DragScreen> {
+  List<int> items = <int>[1, 2, 3, 4, 5];
+
+  // Target order for Maestro drag-and-drop test validation.


It seems Maestro is a testing framework, but still I'm a bit confused as to what information this comment is conveying to the reader?

It was a leftover comment from testing. Removed.

LongCatIsLooong · 2026-08-15T00:11:21Z

  XCTAssertNotNil([child accessibilityContainer]);
 }

+- (void)testRemovedSemanticsDoesNotDetachReparentedChild {


nit: is this test necessary? The unit test in SemanticsObjectTest.mm verifies the oversight in setChildren is fixed, and the integration test verifies with the fix reorderable list's semantics work correctly?

Fair point. This one created the reparenting scenario by itself but with the other tests, this is redundant. Removed.

The onReorderItem callback already adjusts the destination after removing the source item. Insert directly at that index so downward drags do not move one position too early.

cbracken

I kicked the tests for you and have (tried) to re-run the google3 tests (the failure wasn't your code it was a flake in the infra itself :/)

Took at quick review pass while I was here and was wondering why the -1 adjustment, but turns out that this shouldn't be necessary. See inline comment. Other than that, just @LongCatIsLooong's comments to address.

cbracken · 2026-08-16T23:31:14Z

+    setState(() {
+      if (newIndex > oldIndex) {
+        newIndex -= 1;
+      }


It looks like this newIndex -= 1 was required for the old onReorder callback but onReorderItem already handles this internally:

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

Lines 1022 to 1025 in 875be1c

// Removing an item at the old index shortens the list by one.

if (newIndex > oldIndex) {

newIndex -= 1;

}

Updated and renamed. testDragScreen in PlatformViewUITests should've caught this but apparently I didn't run that test until now. Might have been too caught up in the manual testing or disturbed the test myself.

cbracken · 2026-08-16T23:37:34Z

+
+  bool get isCorrectOrder => listEquals(items, targetOrder);
+
+  void _onReorder(int oldIndex, int newIndex) {


You should rename this _onReorderItem since this is the handler being passed to that param down below.

The SemanticsObject unit test covers parent ownership, while the iOS integration test covers the native hierarchy and frame after a reorder. Remove the overlapping bridge-level scenario.

AfzalivE · 2026-08-19T05:27:38Z

@cbracken @LongCatIsLooong Thanks for the reviews. Addressed the comments and made the updates.

flutter/flutter@0cbd1a4...70797e1 2026-09-02 [email protected] [analysis] Upgrade package:analyzer to 14.3.0 and enable custom plugin compilation (flutter/flutter#191590) 2026-09-02 [email protected] Roll Dart SDK from d8d7869d8031 to 9a8fbde80f6c (1 revision) (flutter/flutter#192179) 2026-09-02 [email protected] Roll Skia from dec311244db4 to ae22da2e8308 (1 revision) (flutter/flutter#192177) 2026-09-02 [email protected] [tool] Migrate DoctorCommand to modular dependency injection (flutter/flutter#190758) 2026-09-02 [email protected] Roll Skia from 482b7e285244 to dec311244db4 (3 revisions) (flutter/flutter#192161) 2026-09-02 [email protected] Roll Skia from 28447e9fb8d5 to 482b7e285244 (3 revisions) (flutter/flutter#192157) 2026-09-02 [email protected] feat: Add placeholder to DecorationImage (flutter/flutter#191528) 2026-09-02 [email protected] [Android] Do not schedule engine frames on a detached FlutterJNI (flutter/flutter#191204) 2026-09-02 [email protected] Roll Skia from 3a242fb7cdb3 to 28447e9fb8d5 (1 revision) (flutter/flutter#192145) 2026-09-02 [email protected] Roll Dart SDK from 9164def35347 to d8d7869d8031 (2 revisions) (flutter/flutter#192144) 2026-09-02 [email protected] Add FadeInImageTransition.fadeInOver to fade the image in over the placeholder (flutter/flutter#186246) 2026-09-02 [email protected] Roll Skia from 63d13ec4df6d to 3a242fb7cdb3 (9 revisions) (flutter/flutter#192138) 2026-09-02 [email protected] [flutter_tools] Add --no-plugins flag and disable plugins for benchmark (flutter/flutter#192129) 2026-09-02 [email protected] [tool] Migrate ChannelCommand to modular dependency injection (flutter/flutter#190751) 2026-09-01 [email protected] Add mouseCursor to RawScrollbar (flutter/flutter#185750) 2026-09-01 [email protected] Fix self-comparison and assert typos in TestSemantics (flutter/flutter#191938) 2026-09-01 [email protected] [Linux] Wait for frames to be rendered before using them in another context (flutter/flutter#192094) 2026-09-01 [email protected] [wimp] Turn on multithreading for wimp. (flutter/flutter#191747) 2026-09-01 [email protected] Roll Skia from 3911a1fe7f7a to 63d13ec4df6d (6 revisions) (flutter/flutter#192125) 2026-09-01 [email protected] Remove the redundant flutter/shell/platform/android:robolectric_tests build target (flutter/flutter#192117) 2026-09-01 [email protected] [iOS] Preserve semantics parents after reparenting (flutter/flutter#189686) 2026-09-01 [email protected] [flutter_tools] Report preview reload timing analytics in LspPreviewDetector (flutter/flutter#192120) 2026-09-01 [email protected] [flutter_tools] Implement Templates slice and flutter create integration (flutter/flutter#191748) 2026-09-01 [email protected] Uiscene migrate add2app hosts (flutter/flutter#191847) 2026-09-01 [email protected] Roll Packages from d642322 to 7a7912f (8 revisions) (flutter/flutter#192119) 2026-09-01 [email protected] [web] Anchor flt-semantics-host at 0,0 to fix WebKit semantics offset (flutter/flutter#190486) 2026-09-01 [email protected] Replace Shell::WaitForFirstFrame with an asynchronous API that matches the Shell threading model (flutter/flutter#191841) 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] 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#12727) flutter/flutter@0cbd1a4...70797e1 2026-09-02 [email protected] [analysis] Upgrade package:analyzer to 14.3.0 and enable custom plugin compilation (flutter/flutter#191590) 2026-09-02 [email protected] Roll Dart SDK from d8d7869d8031 to 9a8fbde80f6c (1 revision) (flutter/flutter#192179) 2026-09-02 [email protected] Roll Skia from dec311244db4 to ae22da2e8308 (1 revision) (flutter/flutter#192177) 2026-09-02 [email protected] [tool] Migrate DoctorCommand to modular dependency injection (flutter/flutter#190758) 2026-09-02 [email protected] Roll Skia from 482b7e285244 to dec311244db4 (3 revisions) (flutter/flutter#192161) 2026-09-02 [email protected] Roll Skia from 28447e9fb8d5 to 482b7e285244 (3 revisions) (flutter/flutter#192157) 2026-09-02 [email protected] feat: Add placeholder to DecorationImage (flutter/flutter#191528) 2026-09-02 [email protected] [Android] Do not schedule engine frames on a detached FlutterJNI (flutter/flutter#191204) 2026-09-02 [email protected] Roll Skia from 3a242fb7cdb3 to 28447e9fb8d5 (1 revision) (flutter/flutter#192145) 2026-09-02 [email protected] Roll Dart SDK from 9164def35347 to d8d7869d8031 (2 revisions) (flutter/flutter#192144) 2026-09-02 [email protected] Add FadeInImageTransition.fadeInOver to fade the image in over the placeholder (flutter/flutter#186246) 2026-09-02 [email protected] Roll Skia from 63d13ec4df6d to 3a242fb7cdb3 (9 revisions) (flutter/flutter#192138) 2026-09-02 [email protected] [flutter_tools] Add --no-plugins flag and disable plugins for benchmark (flutter/flutter#192129) 2026-09-02 [email protected] [tool] Migrate ChannelCommand to modular dependency injection (flutter/flutter#190751) 2026-09-01 [email protected] Add mouseCursor to RawScrollbar (flutter/flutter#185750) 2026-09-01 [email protected] Fix self-comparison and assert typos in TestSemantics (flutter/flutter#191938) 2026-09-01 [email protected] [Linux] Wait for frames to be rendered before using them in another context (flutter/flutter#192094) 2026-09-01 [email protected] [wimp] Turn on multithreading for wimp. (flutter/flutter#191747) 2026-09-01 [email protected] Roll Skia from 3911a1fe7f7a to 63d13ec4df6d (6 revisions) (flutter/flutter#192125) 2026-09-01 [email protected] Remove the redundant flutter/shell/platform/android:robolectric_tests build target (flutter/flutter#192117) 2026-09-01 [email protected] [iOS] Preserve semantics parents after reparenting (flutter/flutter#189686) 2026-09-01 [email protected] [flutter_tools] Report preview reload timing analytics in LspPreviewDetector (flutter/flutter#192120) 2026-09-01 [email protected] [flutter_tools] Implement Templates slice and flutter create integration (flutter/flutter#191748) 2026-09-01 [email protected] Uiscene migrate add2app hosts (flutter/flutter#191847) 2026-09-01 [email protected] Roll Packages from d642322 to 7a7912f (8 revisions) (flutter/flutter#192119) 2026-09-01 [email protected] [web] Anchor flt-semantics-host at 0,0 to fix WebKit semantics offset (flutter/flutter#190486) 2026-09-01 [email protected] Replace Shell::WaitForFirstFrame with an asynchronous API that matches the Shell threading model (flutter/flutter#191841) 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] 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 OverlayPortal semantics bounds corruption (#192139) (#193420) Cherry-picks #189686 and #192139 into `flutter-3.47-candidate.0` (stable). Both applied cleanly with `git cherry-pick -x`; both touch only `SemanticsObject.mm` (+ tests). ### Issue Link #182604 · #100946 ### Impacted Users End users of iOS apps built with stable who rely on VoiceOver / Switch Control, and teams driving XCUITest / Maestro against Flutter apps. Any route that mounts a Material `Slider` is affected out of the box: `Slider` keeps its value-indicator `OverlayPortal` shown from construction (`slider.dart`: `OverlayPortalController(...)..show()`), so no popover, menu or reorder is needed to trigger it. ### Impact Description Since fccfa97 an `OverlayPortal` child has a different parent in traversal order and in hit-test order. The iOS accessibility bridge overwrote the native `SemanticsObject.parent` with the hit-test one (and cleared parents of moved children), so the parent chain used to compute `accessibilityFrame` no longer reaches the root: every element of the route reports a frame scaled by 1/devicePixelRatio (exactly 1/3 on a 3x device) and anchored top-left. VoiceOver touch exploration focuses the wrong place; `XCUIElement.tap()` misses the visible control. Measured on iPhone 16 Pro Max / iOS 26.7 with Flutter 3.44.8 (stable 3.47.5 has the same `SemanticsObject.mm`): a full-width CTA laid out at `{{32, 834}, {376, 56}}` is published as `{{10.7, 278.0}, {125.3, 18.7}}`; a player route with a `Slider` is 1/3 from its first frame. The corruption persists after the portal unmounts and after background/foreground. ### Changelog Description [flutter/182604](#182604) When a route shows an `OverlayPortal` on iOS (including any Material `Slider`), accessibility frames are shrunk by the device pixel ratio and anchored to the top-left, so VoiceOver focus and XCUITest taps miss the visible controls. ### Workaround Replace Material `Slider` with `CupertinoSlider` (no `OverlayPortal`) on affected routes and avoid `OverlayPortal` altogether. Not viable for apps using Material menus / dropdowns or third-party popovers. ### Risk Low. Parent bookkeeping only: #189686 clears `child.parent` only when the object still owns it; #192139 stops the hit-test-order setter from mutating `parent`. No behaviour change when traversal and hit-test parents coincide. ### Cherry-pick diff composition The two upstream PRs touch the same function, so the composed diff on `SemanticsObject.mm` (`+6 -8`) matches neither of them individually — upstream, #189686 is `+9 -3` on this file and #192139 is `+0 -8`. Net against the `flutter-3.47-candidate.0` base: | site | net effect vs. base | |---|---| | `dealloc` | `+3 -1` — guard becomes `if (child.parent == self) { child.parent = nil; }` | | `setChildren` | `+3 -1` — same guard | | `setChildrenInHitTestOrder` | `-6` — #189686 adds the guard here too, then #192139 deletes both parent loops outright, so those 3 added lines never survive and the block's 6 original lines go away | Additions `3 + 3 = 6`; deletions `1 + 1 + 6 = 8`. The three "missing" additions are the ones the second commit removes from the first. No conflict was resolved by hand — both applied cleanly with `git cherry-pick -x`. ### Test Coverage Yes. #189686 adds an iOS XCUITest (`testReorderableListAccessibilityHierarchyUpdates`) asserting the accessibility frame after reparenting; #192139 adds `SemanticsObjectTest.mm` coverage. Both have been on master since 2026-09-01/03 and ship in beta 3.49.0-0.1.pre. ### Validation Steps 1. On a 3x iOS device, push a route (e.g. `MaterialApp.router` + `GoRoute`) whose body contains a Material `Slider`. 2. Print `XCUIApplication().debugDescription` from an XCUITest, or inspect with Accessibility Inspector. 3. Before: every element of the route reports a frame at 1/3 of its logical size near (0,0). After: frames match the visible layout, and `XCUIElement.tap()` / VoiceOver touch exploration hit the visible controls.

github-actions Bot added platform-ios iOS applications specifically engine flutter/engine related. See also e: labels. a: accessibility Accessibility, e.g. VoiceOver or TalkBack. (aka a11y) team-ios Owned by iOS platform team labels Jul 18, 2026

AfzalivE added 3 commits July 18, 2026 10:35

Add iOS reorder semantics regression test

dc41b6c

Exercise the default mobile long-press reorder path and verify that the native iOS semantic hierarchy preserves the reordered item's frame. Issue: flutter#100946

Add iOS drag integration coverage

a6bb2aa

Add a deterministic reorder target and native UI test for exercising drag interactions in the iOS platform-view integration app.

AfzalivE force-pushed the afzal/fix-100946 branch from 241e4a0 to a6bb2aa Compare July 18, 2026 08:37

AfzalivE marked this pull request as ready for review July 18, 2026 08:39

AfzalivE requested a review from a team as a code owner July 18, 2026 08:39

gemini-code-assist Bot reviewed Jul 18, 2026

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Comment thread dev/integration_tests/ios_platform_view_tests/lib/drag.dart Outdated

Comment thread dev/integration_tests/ios_platform_view_tests/lib/reorderable_list_semantics.dart

This was referenced Jul 21, 2026

feat: add drag command for drag-and-drop gestures mobile-dev-inc/Maestro#2978

Open

feat: add drag command for drag-and-drop gestures (#1203) mobile-dev-inc/Maestro#3453

Open

LongCatIsLooong requested review from LongCatIsLooong and LouiseHsu July 23, 2026 21:27

LouiseHsu added CICD Run CI/CD and removed CICD Run CI/CD labels Jul 31, 2026

LongCatIsLooong previously approved these changes Aug 15, 2026

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AfzalivE added 2 commits August 15, 2026 15:19

Remove stale comment

1cbfe5e

Fix drag fixture reorder callback

3107bd5

The onReorderItem callback already adjusts the destination after removing the source item. Insert directly at that index so downward drags do not move one position too early.

cbracken reviewed Aug 16, 2026

View reviewed changes

Remove redundant accessibility bridge test

4582a8e

The SemanticsObject unit test covers parent ownership, while the iOS integration test covers the native hierarchy and frame after a reorder. Remove the overlapping bridge-level scenario.

AfzalivE dismissed LongCatIsLooong’s stale review via 4582a8e August 17, 2026 04:55

flutter-dashboard Bot removed the CICD Run CI/CD label Aug 17, 2026

vashworth requested review from LongCatIsLooong and cbracken August 27, 2026 21:38

LouiseHsu added the CICD Run CI/CD label Aug 27, 2026

Merge branch 'master' into afzal/fix-100946

8e1036c

flutter-dashboard Bot removed the CICD Run CI/CD label Aug 27, 2026

LongCatIsLooong added the CICD Run CI/CD label Aug 27, 2026

LongCatIsLooong approved these changes Aug 28, 2026

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LouiseHsu approved these changes Sep 1, 2026

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LouiseHsu added the autosubmit Merge PR when tree becomes green via auto submit App label Sep 1, 2026

auto-submit Bot added this pull request to the merge queue Sep 1, 2026

Merged via the queue into flutter:master with commit 03ebdcd Sep 1, 2026
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flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Sep 1, 2026

AfzalivE deleted the afzal/fix-100946 branch September 1, 2026 22:35

justinmc mentioned this pull request Sep 4, 2026

Flutter Notable Commits - 2026 #181433

Open

JoX23 mentioned this pull request Sep 28, 2026

[stable] [iOS] Preserve semantics parents after reparenting (#189686) + Fix OverlayPortal semantics bounds corruption (#192139) #193420

Merged

	// Removing an item at the old index shortens the list by one.
	if (newIndex > oldIndex) {
	newIndex -= 1;
	}


		bool get isCorrectOrder => listEquals(items, targetOrder);

		void _onReorder(int oldIndex, int newIndex) {

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