Disable backspace/delete handling on iOS & macOS (#115900)

* Disable backspace/delete handling on iOS

* fix tests

* review

* macOS too

* review

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

@@ -19,6 +19,12 @@ import 'text_editing_intents.dart';
 /// lower in the widget tree than this. See the [Action] class for an example
 /// of remapping an [Intent] to a custom [Action].
 ///
+/// The [Shortcuts] widget usually takes precedence over system keybindings.
+/// Proceed with caution if the shortcut you wish to override is also used by
+/// the system. For example, overriding [LogicalKeyboardKey.backspace] could
+/// cause CJK input methods to discard more text than they should when the
+/// backspace key is pressed during text composition on iOS.
+///
 /// {@tool snippet}
 ///
 /// This example shows how to use an additional [Shortcuts] widget to override
@@ -440,6 +446,7 @@ class DefaultTextEditingShortcuts extends StatelessWidget {
 
   static final Map<ShortcutActivator, Intent> _macDisablingTextShortcuts = <ShortcutActivator, Intent>{
     ..._commonDisablingTextShortcuts,
+    ..._iOSDisablingTextShortcuts,
     const SingleActivator(LogicalKeyboardKey.escape): const DoNothingAndStopPropagationTextIntent(),
     const SingleActivator(LogicalKeyboardKey.tab): const DoNothingAndStopPropagationTextIntent(),
     const SingleActivator(LogicalKeyboardKey.tab, shift: true): const DoNothingAndStopPropagationTextIntent(),
@@ -447,6 +454,20 @@ class DefaultTextEditingShortcuts extends StatelessWidget {
     const SingleActivator(LogicalKeyboardKey.arrowUp, shift: true, alt: true): const DoNothingAndStopPropagationTextIntent(),
   };
 
+  // Hand backspace/delete events that do not depend on text layout (delete
+  // character and delete to the next word) back to the IME to allow it to
+  // update composing text properly.
+  static const Map<ShortcutActivator, Intent> _iOSDisablingTextShortcuts = <ShortcutActivator, Intent>{
+    SingleActivator(LogicalKeyboardKey.backspace): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.backspace, shift: true): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.delete): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.delete, shift: true): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.backspace, alt: true, shift: true): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.backspace, alt: true): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.delete, alt: true, shift: true): DoNothingAndStopPropagationTextIntent(),
+    SingleActivator(LogicalKeyboardKey.delete, alt: true): DoNothingAndStopPropagationTextIntent(),
+  };
+
   static Map<ShortcutActivator, Intent> get _shortcuts {
     switch (defaultTargetPlatform) {
       case TargetPlatform.android:
@@ -469,13 +490,13 @@ class DefaultTextEditingShortcuts extends StatelessWidget {
       return _webDisablingTextShortcuts;
     }
     switch (defaultTargetPlatform) {
-
       case TargetPlatform.android:
       case TargetPlatform.fuchsia:
-      case TargetPlatform.iOS:
       case TargetPlatform.linux:
       case TargetPlatform.windows:
         return null;
+      case TargetPlatform.iOS:
+        return _iOSDisablingTextShortcuts;
       case TargetPlatform.macOS:
         return _macDisablingTextShortcuts;
     }

packages/flutter/test/widgets/default_text_editing_shortcuts_test.dart

@@ -44,6 +44,87 @@ void main() {
       ),
     );
   }
+
+  group('iOS: do not delete/backspace events', () {
+    final TargetPlatformVariant iOS = TargetPlatformVariant.only(TargetPlatform.iOS);
+    final FocusNode editable = FocusNode();
+    final FocusNode spy = FocusNode();
+
+    testWidgets('backspace with and without word modifier', (WidgetTester tester) async {
+      tester.binding.testTextInput.unregister();
+      addTearDown(tester.binding.testTextInput.register);
+
+      await tester.pumpWidget(
+        buildSpyAboveEditableText(
+          editableFocusNode: editable,
+          spyFocusNode: spy,
+        ),
+      );
+      editable.requestFocus();
+      await tester.pump();
+      final ActionSpyState state = tester.state<ActionSpyState>(find.byType(ActionSpy));
+
+      for (int altShiftState = 0; altShiftState < 1 << 2; altShiftState += 1) {
+        final bool alt = altShiftState & 0x1 != 0;
+        final bool shift = altShiftState & 0x2 != 0;
+        await sendKeyCombination(tester, SingleActivator(LogicalKeyboardKey.backspace, alt: alt, shift: shift));
+      }
+      await tester.pump();
+
+      expect(state.lastIntent, isNull);
+    }, variant: iOS);
+
+    testWidgets('delete with and without word modifier', (WidgetTester tester) async {
+      tester.binding.testTextInput.unregister();
+      addTearDown(tester.binding.testTextInput.register);
+
+      await tester.pumpWidget(
+        buildSpyAboveEditableText(
+          editableFocusNode: editable,
+          spyFocusNode: spy,
+        ),
+      );
+      editable.requestFocus();
+      await tester.pump();
+      final ActionSpyState state = tester.state<ActionSpyState>(find.byType(ActionSpy));
+
+      for (int altShiftState = 0; altShiftState < 1 << 2; altShiftState += 1) {
+        final bool alt = altShiftState & 0x1 != 0;
+        final bool shift = altShiftState & 0x2 != 0;
+        await sendKeyCombination(tester, SingleActivator(LogicalKeyboardKey.delete, alt: alt, shift: shift));
+      }
+      await tester.pump();
+
+      expect(state.lastIntent, isNull);
+    }, variant: iOS);
+
+    testWidgets('Exception: deleting to line boundary is handled by the framework', (WidgetTester tester) async {
+      tester.binding.testTextInput.unregister();
+      addTearDown(tester.binding.testTextInput.register);
+
+      await tester.pumpWidget(
+        buildSpyAboveEditableText(
+          editableFocusNode: editable,
+          spyFocusNode: spy,
+        ),
+      );
+      editable.requestFocus();
+      await tester.pump();
+      final ActionSpyState state = tester.state<ActionSpyState>(find.byType(ActionSpy));
+
+      for (int keyState = 0; keyState < 1 << 2; keyState += 1) {
+        final bool shift = keyState & 0x1 != 0;
+        final LogicalKeyboardKey key = keyState & 0x2 != 0 ? LogicalKeyboardKey.delete : LogicalKeyboardKey.backspace;
+
+        state.lastIntent = null;
+        final SingleActivator activator = SingleActivator(key, meta: true, shift: shift);
+        await sendKeyCombination(tester, activator);
+        await tester.pump();
+        expect(state.lastIntent, isA<DeleteToLineBreakIntent>(), reason: '$activator');
+      }
+    }, variant: iOS);
+  }, skip: kIsWeb); // [intended] specific tests target non-web.
+
   group('macOS does not accept shortcuts if focus under EditableText', () {
     final TargetPlatformVariant macOSOnly = TargetPlatformVariant.only(TargetPlatform.macOS);
 
@@ -400,6 +481,10 @@ class ActionSpyState extends State<ActionSpy> {
     ExtendSelectionVerticallyToAdjacentLineIntent: CallbackAction<ExtendSelectionVerticallyToAdjacentLineIntent>(onInvoke: _captureIntent),
     ExtendSelectionToDocumentBoundaryIntent: CallbackAction<ExtendSelectionToDocumentBoundaryIntent>(onInvoke: _captureIntent),
     ExtendSelectionToNextWordBoundaryOrCaretLocationIntent: CallbackAction<ExtendSelectionToNextWordBoundaryOrCaretLocationIntent>(onInvoke: _captureIntent),
+
+    DeleteToLineBreakIntent: CallbackAction<DeleteToLineBreakIntent>(onInvoke: _captureIntent),
+    DeleteToNextWordBoundaryIntent: CallbackAction<DeleteToNextWordBoundaryIntent>(onInvoke: _captureIntent),
+    DeleteCharacterIntent: CallbackAction<DeleteCharacterIntent>(onInvoke: _captureIntent),
   };
 
   // ignore: use_setters_to_change_properties

packages/flutter/test/widgets/editable_text_shortcuts_test.dart

@@ -150,7 +150,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 19),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('backspace readonly', (WidgetTester tester) async {
           controller.text = testText;
@@ -215,7 +215,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 71),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('backspace inside of a cluster', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -236,7 +236,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('backspace at cluster boundary', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -257,7 +257,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
       });
 
       group('delete: ', () {
@@ -287,7 +287,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 20),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('delete readonly', (WidgetTester tester) async {
           controller.text = testText;
@@ -305,7 +305,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 20, affinity: TextAffinity.upstream),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('delete at start', (WidgetTester tester) async {
           controller.text = testText;
@@ -328,7 +328,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('delete at end', (WidgetTester tester) async {
           controller.text = testText;
@@ -373,7 +373,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('delete at cluster boundary', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -394,7 +394,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 8),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
       });
 
       group('Non-collapsed delete', () {
@@ -420,7 +420,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 8),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('at the boundaries of a cluster', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -441,7 +441,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 8),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('cross-cluster', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -462,7 +462,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('cross-cluster obscured text', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -483,7 +483,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 1),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
       });
 
       group('word modifier + backspace', () {
@@ -516,7 +516,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 24),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('readonly', (WidgetTester tester) async {
           controller.text = testText;
@@ -581,7 +581,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 71),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('inside of a cluster', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -602,7 +602,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('at cluster boundary', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -623,7 +623,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
       });
 
       group('word modifier + delete', () {
@@ -656,7 +656,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 23),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('readonly', (WidgetTester tester) async {
           controller.text = testText;
@@ -697,7 +697,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('at end', (WidgetTester tester) async {
           controller.text = testText;
@@ -735,7 +735,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 0),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
 
         testWidgets('at cluster boundary', (WidgetTester tester) async {
           controller.text = testCluster;
@@ -756,7 +756,7 @@ void main() {
             controller.selection,
             const TextSelection.collapsed(offset: 8),
           );
-        }, variant: TargetPlatformVariant.all());
+        }, variant: TargetPlatformVariant.all(excluding: <TargetPlatform>{ TargetPlatform.iOS }));
       });
 
       group('line modifier + backspace', () {

packages/flutter/test/widgets/editable_text_test.dart

@@ -6330,69 +6330,71 @@ void main() {
     expect(controller.text, equals(testText), reason: 'on $platform');
     expect((await Clipboard.getData(Clipboard.kTextPlain))!.text, equals(testText));
 
-    // Delete
-    await sendKeys(
-      tester,
-      <LogicalKeyboardKey>[
-        LogicalKeyboardKey.delete,
-      ],
-      targetPlatform: defaultTargetPlatform,
-    );
-    expect(
-      selection,
-      equals(
-        const TextSelection(
-          baseOffset: 0,
-          extentOffset: 0,
+    if (defaultTargetPlatform != TargetPlatform.iOS) {
+      // Delete
+      await sendKeys(
+        tester,
+        <LogicalKeyboardKey>[
+          LogicalKeyboardKey.delete,
+        ],
+        targetPlatform: defaultTargetPlatform,
+      );
+      expect(
+        selection,
+        equals(
+          const TextSelection(
+            baseOffset: 0,
+            extentOffset: 0,
+          ),
         ),
-      ),
-      reason: 'on $platform',
-    );
-    expect(controller.text, isEmpty, reason: 'on $platform');
+        reason: 'on $platform',
+      );
+      expect(controller.text, isEmpty, reason: 'on $platform');
 
-    controller.text = 'abc';
-    controller.selection = const TextSelection(baseOffset: 2, extentOffset: 2);
+      controller.text = 'abc';
+      controller.selection = const TextSelection(baseOffset: 2, extentOffset: 2);
 
-    // Backspace
-    await sendKeys(
-      tester,
-      <LogicalKeyboardKey>[
-        LogicalKeyboardKey.backspace,
-      ],
-      targetPlatform: defaultTargetPlatform,
-    );
-    expect(
-      selection,
-      equals(
-        const TextSelection(
-          baseOffset: 1,
-          extentOffset: 1,
+      // Backspace
+      await sendKeys(
+        tester,
+        <LogicalKeyboardKey>[
+          LogicalKeyboardKey.backspace,
+        ],
+        targetPlatform: defaultTargetPlatform,
+      );
+      expect(
+        selection,
+        equals(
+          const TextSelection(
+            baseOffset: 1,
+            extentOffset: 1,
+          ),
         ),
-      ),
-      reason: 'on $platform',
-    );
-    expect(controller.text, 'ac', reason: 'on $platform');
+        reason: 'on $platform',
+      );
+      expect(controller.text, 'ac', reason: 'on $platform');
 
-    // Shift-backspace (same as backspace)
-    await sendKeys(
-      tester,
-      <LogicalKeyboardKey>[
-        LogicalKeyboardKey.backspace,
-      ],
-      shift: true,
-      targetPlatform: defaultTargetPlatform,
-    );
-    expect(
-      selection,
-      equals(
-        const TextSelection(
-          baseOffset: 0,
-          extentOffset: 0,
+      // Shift-backspace (same as backspace)
+      await sendKeys(
+        tester,
+        <LogicalKeyboardKey>[
+          LogicalKeyboardKey.backspace,
+        ],
+        shift: true,
+        targetPlatform: defaultTargetPlatform,
+      );
+      expect(
+        selection,
+        equals(
+          const TextSelection(
+            baseOffset: 0,
+            extentOffset: 0,
+          ),
         ),
-      ),
-      reason: 'on $platform',
-    );
-    expect(controller.text, 'c', reason: 'on $platform');
+        reason: 'on $platform',
+      );
+      expect(controller.text, 'c', reason: 'on $platform');
+    }
   }
 
   testWidgets('keyboard text selection works (RawKeyEvent)', (WidgetTester tester) async {