Fix crash on two finger selection gesture #168598

Renzo-Olivares · 2025-05-09T15:52:11Z

This change blocks two selection handles from being able to be dragged simultaneously on iOS and the web, this matches the native behavior. On native Android both handles can still be dragged simultaneously this is the behavior observed on Google Keep/ Google Messages and Android's EditText.

Also fixes an issue on iOS where the magnifier would not return after hiding when double tapping and dragging to select and then dragging outside the TextField area. The cause of this issue was because editableText.showMagnifier decides whether to update the magnifier position or show a new one based on whether it was visible, so when it was hidden and we attempt to update it's position, it would try to show a new magnifier which left the magnifier in a broken state. This change makes editableText.showMagnifier depend on whether a magnifier exists instead of just checking it's visibility. Similarly editableText.hideMagnifier now does not depend on the magnifier visibility, instead it internally (selectionOverlay.hideMagnifier) checks if the magnifier exists.

Fixes #168578

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.

loic-sharma · 2025-05-15T22:51:55Z

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

    );
-    _dragStartSelection ??= _selection;
+    _dragStartSelection =
+        defaultTargetPlatform == TargetPlatform.iOS || defaultTargetPlatform == TargetPlatform.macOS


Consider adding a quick comment here. It's not immediately obvious to me why we behave differently here based on the platform.

I kinda thought the same thing while reviewing 👍

justinmc

One idea below to possibly reduce the amount of state, otherwise LGTM 👍

justinmc · 2025-05-15T22:50:09Z

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

+    _dragStartSelection =
+        defaultTargetPlatform == TargetPlatform.iOS || defaultTargetPlatform == TargetPlatform.macOS
+            ? _selection
+            : null;


Just double checking a logical difference: after this change, on iOS/macOS, it's possible that _dragStartSelection will be overwritten when it is non-null, but previously it wouldn't have been.

Good catch, I didn't notice that. I'll update it to meet the original logical difference. It should still only be set on Apple platforms.

justinmc · 2025-05-15T22:55:56Z

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

      _isDraggingEndHandle = false;
      return;
    }
+    if (_blockEndHandleDrag) {


I wonder if you could get rid of the _blockStart/EndHandleDrag booleans by checking something like this here instead:

_isDraggingStartHandle && defaultTargetPlatform == TargetPlatform.iOS || defaultTargetPlatform == TargetPlatform.macOS || kIsWeb

That could be a getter to make things cleaner.

loic-sharma · 2025-05-15T23:02:21Z

packages/flutter/test/material/selection_area_test.dart

+      );
+      final TestGesture gesture = await tester.startGesture(
+        textOffsetToPosition(paragraph, 11),
+      ); // at the 'a'


Should this be 'e' pos?

Same comment for code below

Good catch thanks!

loic-sharma

LGTM, nice work!

justinmc

LGTM 👍

justinmc · 2025-05-16T22:28:17Z

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

+  // On Apple and web platforms only one selection handle can be dragged
+  // at a time, so when the start handle is being dragged on these platforms
+  // the the end handle cannot be dragged.
+  bool get _canDragEndHandle =>


I think these getters and the early returns are really easy to follow now 👍

Renzo-Olivares · 2025-05-16T22:39:14Z

Still looking into an issue with the magnifier after this change.

…tforms

…ng dragged

… in progress (even if blocked by _canDrag*Handle)

…ntry

…lling editableText.showMagnifier

justinmc

LGTM 👍 . The main magnifier fix you mentioned since last time is 42f1efe right?

…168598)

Roll Flutter from 33cdd8ef31dc to 85564cbba9e7 (39 revisions) flutter/flutter@33cdd8e...85564cb 2025-05-23 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Reland2] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#169276)" (flutter/flutter#169347) 2025-05-23 [email protected] Roll Skia from a01ea49f53a4 to 956fd8b14e22 (1 revision) (flutter/flutter#169334) 2025-05-23 [email protected] Roll Dart SDK from 4de10a11ceb9 to 085f110ecf33 (1 revision) (flutter/flutter#169333) 2025-05-23 [email protected] Roll Skia from bcc7e7fce10e to a01ea49f53a4 (1 revision) (flutter/flutter#169329) 2025-05-23 [email protected] Roll Skia from 18b85aced9b7 to bcc7e7fce10e (3 revisions) (flutter/flutter#169323) 2025-05-23 [email protected] Roll Dart SDK from 2a45b2f88a4f to 4de10a11ceb9 (2 revisions) (flutter/flutter#169322) 2025-05-23 [email protected] Remove patching of `package_config.json` from Flutter Pub wrapper. (flutter/flutter#169306) 2025-05-23 [email protected] Add missing dart_dynamic_modules flag for iOS DDM simulator builds (flutter/flutter#169254) 2025-05-23 [email protected] Roll Skia from ea73ccdc1417 to 18b85aced9b7 (6 revisions) (flutter/flutter#169315) 2025-05-23 [email protected] Add flag to exclude focus for hidden children in Visibility, maintainFocusability. Set maintainFocusability to false in IndexedStack (flutter/flutter#159133) 2025-05-23 [email protected] [Reland2] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (flutter/flutter#169276) 2025-05-23 [email protected] Roll Dart SDK from 8f85d89fdc23 to 2a45b2f88a4f (6 revisions) (flutter/flutter#169312) 2025-05-23 [email protected] Removes unnecessary parentheses (flutter/flutter#169015) 2025-05-22 [email protected] Unpin test/test_core/test_api packages (flutter/flutter#169198) 2025-05-22 [email protected] [Engine] Fix an edge case of RoundSuperellipseParam::Contains with sharp corners (flutter/flutter#167977) 2025-05-22 [email protected] Replace goldens in test/cupertino/nav_bar_transition_test.dart (flutter/flutter#169172) 2025-05-22 [email protected] Roll Skia from 13a299964c9f to ea73ccdc1417 (35 revisions) (flutter/flutter#169303) 2025-05-22 [email protected] Increase sub-task timeout for Mac web_tool_tests (flutter/flutter#169307) 2025-05-22 [email protected] Fix crash on two finger selection gesture (flutter/flutter#168598) 2025-05-22 [email protected] Disable the ability to opt-out of `explicit-package-dependencies`. (flutter/flutter#169283) 2025-05-22 [email protected] Fixes tab semantics gets dropped if the child produce a semantics node (flutter/flutter#169233) 2025-05-22 [email protected] Skip `{PLAT}_web_tools_test#expression_evaluation_*_test.dart`, turning tree 🔴 (flutter/flutter#169305) 2025-05-22 [email protected] Update tool-internal `generateLocalizations...()` to never use synthetic (`flutter_gen`) packages (flutter/flutter#169285) 2025-05-22 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Make `build_android_host_app_with_module_aar` build using an aar (#169171)" (flutter/flutter#169287) 2025-05-22 [email protected] Increase sub-task timeout for `web_tool_tests_1_2` (flutter/flutter#169277) 2025-05-22 [email protected] refactor the usage of `MediaQuery.sizeOf(context).height` to use the new `.heightOf(context)` (flutter/flutter#168894) 2025-05-22 [email protected] [tool] Add --no-minify flag to JS Compiler (flutter/flutter#169102) 2025-05-22 [email protected] Update ButtonStyle documentation (flutter/flutter#168062) 2025-05-22 [email protected] Fix the issue where DropdownMenu disposes of the controller. (flutter/flutter#168541) 2025-05-22 [email protected] Add bottomSheetScrimBuilder to Scaffold (flutter/flutter#167335) 2025-05-22 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Reland] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#168396) (#168914)" (flutter/flutter#169250) 2025-05-21 [email protected] Roll Dart SDK from 56940edd099d to 8f85d89fdc23 (6 revisions) (flutter/flutter#169237) 2025-05-21 [email protected] Use gestureSettings.touchSlop in PrimaryPointerGestureRecognizer (flutter/flutter#161549) 2025-05-21 [email protected] Normalize BottomAppBarTheme (continue) (flutter/flutter#168966) 2025-05-21 [email protected] [Reland] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#168396) (flutter/flutter#168914) 2025-05-21 [email protected] Respect `calendarDelegate` in `showDateRangePicker` (flutter/flutter#168290) 2025-05-21 [email protected] Make `build_android_host_app_with_module_aar` build using an aar (flutter/flutter#169171) 2025-05-21 [email protected] Roll Dart SDK from 7c40eba6bf77 to 56940edd099d (flutter/flutter#169135) 2025-05-21 [email protected] Feat: Add full screen dialog support for dialog routes (flutter/flutter#167794) 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. ...

…r#9315) Roll Flutter from 33cdd8ef31dc to 85564cbba9e7 (39 revisions) flutter/flutter@33cdd8e...85564cb 2025-05-23 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Reland2] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#169276)" (flutter/flutter#169347) 2025-05-23 [email protected] Roll Skia from a01ea49f53a4 to 956fd8b14e22 (1 revision) (flutter/flutter#169334) 2025-05-23 [email protected] Roll Dart SDK from 4de10a11ceb9 to 085f110ecf33 (1 revision) (flutter/flutter#169333) 2025-05-23 [email protected] Roll Skia from bcc7e7fce10e to a01ea49f53a4 (1 revision) (flutter/flutter#169329) 2025-05-23 [email protected] Roll Skia from 18b85aced9b7 to bcc7e7fce10e (3 revisions) (flutter/flutter#169323) 2025-05-23 [email protected] Roll Dart SDK from 2a45b2f88a4f to 4de10a11ceb9 (2 revisions) (flutter/flutter#169322) 2025-05-23 [email protected] Remove patching of `package_config.json` from Flutter Pub wrapper. (flutter/flutter#169306) 2025-05-23 [email protected] Add missing dart_dynamic_modules flag for iOS DDM simulator builds (flutter/flutter#169254) 2025-05-23 [email protected] Roll Skia from ea73ccdc1417 to 18b85aced9b7 (6 revisions) (flutter/flutter#169315) 2025-05-23 [email protected] Add flag to exclude focus for hidden children in Visibility, maintainFocusability. Set maintainFocusability to false in IndexedStack (flutter/flutter#159133) 2025-05-23 [email protected] [Reland2] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (flutter/flutter#169276) 2025-05-23 [email protected] Roll Dart SDK from 8f85d89fdc23 to 2a45b2f88a4f (6 revisions) (flutter/flutter#169312) 2025-05-23 [email protected] Removes unnecessary parentheses (flutter/flutter#169015) 2025-05-22 [email protected] Unpin test/test_core/test_api packages (flutter/flutter#169198) 2025-05-22 [email protected] [Engine] Fix an edge case of RoundSuperellipseParam::Contains with sharp corners (flutter/flutter#167977) 2025-05-22 [email protected] Replace goldens in test/cupertino/nav_bar_transition_test.dart (flutter/flutter#169172) 2025-05-22 [email protected] Roll Skia from 13a299964c9f to ea73ccdc1417 (35 revisions) (flutter/flutter#169303) 2025-05-22 [email protected] Increase sub-task timeout for Mac web_tool_tests (flutter/flutter#169307) 2025-05-22 [email protected] Fix crash on two finger selection gesture (flutter/flutter#168598) 2025-05-22 [email protected] Disable the ability to opt-out of `explicit-package-dependencies`. (flutter/flutter#169283) 2025-05-22 [email protected] Fixes tab semantics gets dropped if the child produce a semantics node (flutter/flutter#169233) 2025-05-22 [email protected] Skip `{PLAT}_web_tools_test#expression_evaluation_*_test.dart`, turning tree 🔴 (flutter/flutter#169305) 2025-05-22 [email protected] Update tool-internal `generateLocalizations...()` to never use synthetic (`flutter_gen`) packages (flutter/flutter#169285) 2025-05-22 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Make `build_android_host_app_with_module_aar` build using an aar (#169171)" (flutter/flutter#169287) 2025-05-22 [email protected] Increase sub-task timeout for `web_tool_tests_1_2` (flutter/flutter#169277) 2025-05-22 [email protected] refactor the usage of `MediaQuery.sizeOf(context).height` to use the new `.heightOf(context)` (flutter/flutter#168894) 2025-05-22 [email protected] [tool] Add --no-minify flag to JS Compiler (flutter/flutter#169102) 2025-05-22 [email protected] Update ButtonStyle documentation (flutter/flutter#168062) 2025-05-22 [email protected] Fix the issue where DropdownMenu disposes of the controller. (flutter/flutter#168541) 2025-05-22 [email protected] Add bottomSheetScrimBuilder to Scaffold (flutter/flutter#167335) 2025-05-22 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Reland] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#168396) (#168914)" (flutter/flutter#169250) 2025-05-21 [email protected] Roll Dart SDK from 56940edd099d to 8f85d89fdc23 (6 revisions) (flutter/flutter#169237) 2025-05-21 [email protected] Use gestureSettings.touchSlop in PrimaryPointerGestureRecognizer (flutter/flutter#161549) 2025-05-21 [email protected] Normalize BottomAppBarTheme (continue) (flutter/flutter#168966) 2025-05-21 [email protected] [Reland] Implements UISceneDelegate dynamically w/ FlutterLaunchEngine (#168396) (flutter/flutter#168914) 2025-05-21 [email protected] Respect `calendarDelegate` in `showDateRangePicker` (flutter/flutter#168290) 2025-05-21 [email protected] Make `build_android_host_app_with_module_aar` build using an aar (flutter/flutter#169171) 2025-05-21 [email protected] Roll Dart SDK from 7c40eba6bf77 to 56940edd099d (flutter/flutter#169135) 2025-05-21 [email protected] Feat: Add full screen dialog support for dialog routes (flutter/flutter#167794) 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. ...

…168598)

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Renzo Olivares added 7 commits May 21, 2025 16:26

Only allow both handles to be dragged simultaneously on non-Apple pla…

3f08e67

…tforms

move some logic into SelectionOverlay

0f9ad79

block dual selection handle drag on web

f440bf3

add fix for selectable region

064f1f4

add tests

441d3e1

add regression test

9cf7175

Add more tests

df262ce

Renzo Olivares added 10 commits May 21, 2025 16:26

Address reviewer comments

756e047

add docs

911ecf8

fix logic

0627c56

handle case where opposite handle drag ends while other handle is bei…

4101d0b

…ng dragged

prevent magnifier from hiding and toolbar from showing when a drag is…

deea7f4

… in progress (even if blocked by _canDrag*Handle)

Update selectable region

67c1445

short-circuit showMagnifier if there is already a magnifier overlay e…

311b3b7

…ntry

Fix issue where magnifier would not return after being hidden when ca…

42f1efe

…lling editableText.showMagnifier

Add test

b48ab12

add cupertino test

11a1205

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Fix crash on two finger selection gesture #168598

Fix crash on two finger selection gesture #168598

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