Disable blinking cursor when EditableText.showCursor is false (#127562)

Fixes https://github.com/flutter/flutter/issues/108187

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

@@ -2610,12 +2610,10 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     final bool newTickerEnabled = TickerMode.of(context);
     if (_tickersEnabled != newTickerEnabled) {
       _tickersEnabled = newTickerEnabled;
-      if (_tickersEnabled && _cursorActive) {
+      if (_showBlinkingCursor) {
         _startCursorBlink();
       } else if (!_tickersEnabled && _cursorTimer != null) {
-        // Cannot use _stopCursorBlink because it would reset _cursorActive.
-        _cursorTimer!.cancel();
-        _cursorTimer = null;
+        _stopCursorBlink();
       }
     }
 
@@ -2707,6 +2705,10 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
         );
       }
     }
+
+    if (widget.showCursor != oldWidget.showCursor) {
+      _startOrStopCursorTimerIfNeeded();
+    }
     final bool canPaste = widget.selectionControls is TextSelectionHandleControls
         ? pasteEnabled
         : widget.selectionControls?.canPaste(this) ?? false;
@@ -3655,6 +3657,8 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     _cursorVisibilityNotifier.value = widget.showCursor && _cursorBlinkOpacityController.value > 0;
   }
 
+  bool get _showBlinkingCursor => _hasFocus && _value.selection.isCollapsed && widget.showCursor && _tickersEnabled;
+
   /// Whether the blinking cursor is actually visible at this precise moment
   /// (it's hidden half the time, since it blinks).
   @visibleForTesting
@@ -3673,13 +3677,11 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   int _obscureShowCharTicksPending = 0;
   int? _obscureLatestCharIndex;
 
-  // Indicates whether the cursor should be blinking right now (but it may
-  // actually not blink because it's disabled via TickerMode.of(context)).
-  bool _cursorActive = false;
-
   void _startCursorBlink() {
     assert(!(_cursorTimer?.isActive ?? false) || !(_backingCursorBlinkOpacityController?.isAnimating ?? false));
-    _cursorActive = true;
+    if (!widget.showCursor) {
+      return;
+    }
     if (!_tickersEnabled) {
       return;
     }
@@ -3719,7 +3721,6 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   }
 
   void _stopCursorBlink({ bool resetCharTicks = true }) {
-    _cursorActive = false;
     _cursorBlinkOpacityController.value = 0.0;
     _cursorTimer?.cancel();
     _cursorTimer = null;
@@ -3729,11 +3730,10 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   }
 
   void _startOrStopCursorTimerIfNeeded() {
-    if (_cursorTimer == null && _hasFocus && _value.selection.isCollapsed) {
-      _startCursorBlink();
-    }
-    else if (_cursorActive && (!_hasFocus || !_value.selection.isCollapsed)) {
+    if (!_showBlinkingCursor) {
       _stopCursorBlink();
+    } else if (_cursorTimer == null) {
+      _startCursorBlink();
     }
   }
 

packages/flutter/test/widgets/editable_text_cursor_test.dart

@@ -771,6 +771,54 @@ void main() {
     await checkCursorBlinking();
   });
 
+  testWidgets('Turning showCursor off stops the cursor', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/108187.
+    final bool debugDeterministicCursor = EditableText.debugDeterministicCursor;
+    // This doesn't really matter.
+    EditableText.debugDeterministicCursor = false;
+    addTearDown(() { EditableText.debugDeterministicCursor = debugDeterministicCursor; });
+    const Key key = Key('EditableText');
+
+    Widget buildEditableText({ required bool showCursor }) {
+      return MediaQuery(
+        data: const MediaQueryData(),
+        child: Directionality(
+          textDirection: TextDirection.ltr,
+          child: EditableText(
+            key: key,
+            backgroundCursorColor: Colors.grey,
+            // Use animation controller to animate cursor blink for testing.
+            cursorOpacityAnimates: true,
+            controller: controller,
+            focusNode: focusNode,
+            style: textStyle,
+            cursorColor: cursorColor,
+            showCursor: showCursor,
+          ),
+        ),
+      );
+    }
+    late final EditableTextState editableTextState = tester.state(find.byKey(key));
+    await tester.pumpWidget(buildEditableText(showCursor: false));
+    await tester.tap(find.byKey(key));
+    await tester.pump();
+
+    // No cursor even when focused.
+    expect(editableTextState.cursorCurrentlyVisible, false);
+
+    // The EditableText still has focus, so the cursor should starts blinking.
+    await tester.pumpWidget(buildEditableText(showCursor: true));
+    expect(editableTextState.cursorCurrentlyVisible, true);
+    await tester.pump();
+    expect(editableTextState.cursorCurrentlyVisible, true);
+
+    // readOnly disables blinking cursor.
+    await tester.pumpWidget(buildEditableText(showCursor: false));
+    expect(editableTextState.cursorCurrentlyVisible, false);
+    await tester.pump();
+    expect(editableTextState.cursorCurrentlyVisible, false);
+  });
+
   // Regression test for https://github.com/flutter/flutter/pull/30475.
   testWidgets('Trying to select with the floating cursor does not crash', (WidgetTester tester) async {
     const String text = 'hello world this is fun and cool and awesome!';