Provide caret rect to text input plugin (#77608)

packages/flutter/lib/src/services/text_input.dart

@@ -926,6 +926,7 @@ class TextInputConnection {
   Size? _cachedSize;
   Matrix4? _cachedTransform;
   Rect? _cachedRect;
+  Rect? _cachedCaretRect;
 
   static int _nextId = 1;
   final int _id;
@@ -1028,6 +1029,24 @@ class TextInputConnection {
     );
   }
 
+  /// Sends the coordinates of caret rect. This is used on macOS for positioning
+  /// the accent selection menu.
+  void setCaretRect(Rect rect) {
+    assert(rect != null);
+    if (rect == _cachedCaretRect)
+      return;
+    _cachedCaretRect = rect;
+    final Rect validRect = rect.isFinite ? rect : Offset.zero & const Size(-1, -1);
+    TextInput._instance._setCaretRect(
+      <String, dynamic>{
+        'width': validRect.width,
+        'height': validRect.height,
+        'x': validRect.left,
+        'y': validRect.top,
+      },
+    );
+  }
+
   /// Send text styling information.
   ///
   /// This information is used by the Flutter Web Engine to change the style
@@ -1416,6 +1435,13 @@ class TextInput {
     );
   }
 
+  void _setCaretRect(Map<String, dynamic> args) {
+    _channel.invokeMethod<void>(
+      'TextInput.setCaretRect',
+      args,
+    );
+  }
+
   void _setStyle(Map<String, dynamic> args) {
     _channel.invokeMethod<void>(
       'TextInput.setStyle',

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

@@ -2027,6 +2027,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
       _textInputConnection!.show();
       _updateSizeAndTransform();
       _updateComposingRectIfNeeded();
+      _updateCaretRectIfNeeded();
       if (_needsAutofill) {
         // Request autofill AFTER the size and the transform have been sent to
         // the platform text input plugin.
@@ -2436,6 +2437,19 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     }
   }
 
+  void _updateCaretRectIfNeeded() {
+    if (_hasInputConnection) {
+      if (renderEditable.selection != null && renderEditable.selection!.isValid &&
+          renderEditable.selection!.isCollapsed) {
+        final TextPosition currentTextPosition = TextPosition(offset: renderEditable.selection!.baseOffset);
+        final Rect caretRect = renderEditable.getLocalRectForCaret(currentTextPosition);
+        _textInputConnection!.setCaretRect(caretRect);
+      }
+      SchedulerBinding.instance!
+          .addPostFrameCallback((Duration _) => _updateCaretRectIfNeeded());
+    }
+  }
+
   TextDirection get _textDirection {
     final TextDirection result = widget.textDirection ?? Directionality.of(context);
     assert(result != null, '$runtimeType created without a textDirection and with no ambient Directionality.');

packages/flutter/test/widgets/editable_text_test.dart

@@ -3483,6 +3483,100 @@ void main() {
     );
   });
 
+  group('setCaretRect', () {
+    Widget builder() {
+      return MaterialApp(
+        home: MediaQuery(
+          data: const MediaQueryData(devicePixelRatio: 1.0),
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: Center(
+              child: Material(
+                child: EditableText(
+                  backgroundCursorColor: Colors.grey,
+                  controller: controller,
+                  focusNode: FocusNode(),
+                  style: textStyle,
+                  cursorColor: Colors.blue,
+                  selectionControls: materialTextSelectionControls,
+                  keyboardType: TextInputType.text,
+                  onChanged: (String value) {},
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    testWidgets(
+      'called with proper coordinates',
+      (WidgetTester tester) async {
+        controller.value = TextEditingValue(text: 'a' * 50);
+        await tester.pumpWidget(builder());
+        await tester.showKeyboard(find.byType(EditableText));
+
+        expect(tester.testTextInput.log, contains(
+          matchesMethodCall(
+            'TextInput.setCaretRect',
+            args: allOf(
+              // No composing text so the width should not be too wide because
+              // it's empty.
+              containsPair('x', equals(700)),
+              containsPair('y', equals(0)),
+              containsPair('width', equals(2)),
+              containsPair('height', equals(14)),
+            ),
+          ),
+        ));
+
+        tester.testTextInput.log.clear();
+
+        controller.value = TextEditingValue(
+          text: 'a' * 50, selection: const TextSelection(baseOffset: 0, extentOffset: 0));
+        await tester.pump();
+
+        expect(tester.testTextInput.log, contains(
+          matchesMethodCall(
+            'TextInput.setCaretRect',
+            // Now the composing range is not empty.
+            args: allOf(
+              containsPair('x', equals(0)),
+              containsPair('y', equals(0)),
+            )
+          ),
+        ));
+    }, skip: isBrowser); // Related to https://github.com/flutter/flutter/issues/66089
+
+    testWidgets(
+      'only send updates when necessary',
+      (WidgetTester tester) async {
+        controller.value = TextEditingValue(text: 'a' * 100);
+        await tester.pumpWidget(builder());
+        await tester.showKeyboard(find.byType(EditableText));
+
+        expect(tester.testTextInput.log, contains(matchesMethodCall('TextInput.setCaretRect')));
+
+        tester.testTextInput.log.clear();
+
+        // Should not send updates every frame.
+        await tester.pump();
+
+        expect(tester.testTextInput.log, isNot(contains(matchesMethodCall('TextInput.setCaretRect'))));
+    });
+
+    testWidgets(
+      'not sent with selection',
+      (WidgetTester tester) async {
+        controller.value = TextEditingValue(
+          text: 'a' * 100, selection: const TextSelection(baseOffset: 0, extentOffset: 10));
+        await tester.pumpWidget(builder());
+        await tester.showKeyboard(find.byType(EditableText));
+
+        expect(tester.testTextInput.log, isNot(contains(matchesMethodCall('TextInput.setCaretRect'))));
+    });
+  });
+
   group('setMarkedTextRect', () {
     Widget builder() {
       return MaterialApp(
@@ -5437,6 +5531,7 @@ void main() {
       'TextInput.setEditingState',
       'TextInput.setEditingState',
       'TextInput.show',
+      'TextInput.setCaretRect',
     ];
     expect(
       tester.testTextInput.log.map((MethodCall m) => m.method),
@@ -5480,6 +5575,7 @@ void main() {
       'TextInput.setEditingState',
       'TextInput.setEditingState',
       'TextInput.show',
+      'TextInput.setCaretRect',
       'TextInput.show',
     ];
     expect(tester.testTextInput.log.length, logOrder.length);
@@ -5529,6 +5625,7 @@ void main() {
       'TextInput.setEditingState',
       'TextInput.setEditingState',
       'TextInput.show',
+      'TextInput.setCaretRect',
       'TextInput.setEditingState',
     ];