Make disabled buttons/chips/text fields not be focusable. (#38726)

This changes the behavior of text fields, Material buttons, and Chips so that if they are disabled they lose focus. Before this change, it was possible to disable a control and then use focus traversal to reach it anyhow, and in the case of text fields, enter text into a disabled field.

Fixes #33985

packages/flutter/lib/src/material/button.dart

@@ -332,6 +332,7 @@ class _RawMaterialButtonState extends State<RawMaterialButton> {
 
     final Widget result = Focus(
       focusNode: widget.focusNode,
+      canRequestFocus: widget.enabled,
       onFocusChange: _handleFocusedChanged,
       autofocus: widget.autofocus,
       child: ConstrainedBox(

packages/flutter/lib/src/material/chip.dart

@@ -1728,6 +1728,7 @@ class _RawChipState extends State<RawChip> with TickerProviderStateMixin<RawChip
       onFocusChange: _handleFocus,
       focusNode: widget.focusNode,
       autofocus: widget.autofocus,
+      canRequestFocus: widget.isEnabled,
       child: Material(
         elevation: isTapping ? pressElevation : elevation,
         shadowColor: widget.selected ? selectedShadowColor : shadowColor,

packages/flutter/lib/src/material/icon_button.dart

@@ -313,6 +313,7 @@ class IconButton extends StatelessWidget {
       child: Focus(
         focusNode: focusNode,
         autofocus: autofocus,
+        canRequestFocus: onPressed != null,
         child: InkResponse(
           onTap: onPressed,
           child: result,

packages/flutter/lib/src/material/text_field.dart

@@ -686,6 +686,8 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
   bool get selectionEnabled => widget.selectionEnabled;
   // End of API for TextSelectionGestureDetectorBuilderDelegate.
 
+  bool get _isEnabled =>  widget.enabled ?? widget.decoration?.enabled ?? true;
+
   InputDecoration _getEffectiveDecoration() {
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     final ThemeData themeData = Theme.of(context);
@@ -755,8 +757,10 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
   void initState() {
     super.initState();
     _selectionGestureDetectorBuilder = _TextFieldSelectionGestureDetectorBuilder(state: this);
-    if (widget.controller == null)
+    if (widget.controller == null) {
       _controller = TextEditingController();
+    }
+    _effectiveFocusNode.canRequestFocus = _isEnabled;
   }
 
   @override
@@ -766,11 +770,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
       _controller = TextEditingController.fromValue(oldWidget.controller.value);
     else if (widget.controller != null && oldWidget.controller == null)
       _controller = null;
-    final bool isEnabled = widget.enabled ?? widget.decoration?.enabled ?? true;
-    final bool wasEnabled = oldWidget.enabled ?? oldWidget.decoration?.enabled ?? true;
-    if (wasEnabled && !isEnabled) {
-      _effectiveFocusNode.unfocus();
-    }
+    _effectiveFocusNode.canRequestFocus = _isEnabled;
     if (_effectiveFocusNode.hasFocus && widget.readOnly != oldWidget.readOnly) {
       if(_effectiveController.selection.isCollapsed) {
         _showSelectionHandles = !widget.readOnly;
@@ -1045,7 +1045,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
         onEnter: _handleMouseEnter,
         onExit: _handleMouseExit,
         child: IgnorePointer(
-          ignoring: !(widget.enabled ?? widget.decoration?.enabled ?? true),
+          ignoring: !_isEnabled,
           child: _selectionGestureDetectorBuilder.buildGestureDetector(
             behavior: HitTestBehavior.translucent,
             child: child,

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

@@ -391,7 +391,8 @@ class FocusNode with DiagnosticableTreeMixin, ChangeNotifier {
   set skipTraversal(bool value) {
     if (value != _skipTraversal) {
       _skipTraversal = value;
-      _notify();
+      _manager?._dirtyNodes?.add(this);
+      _manager?._markNeedsUpdate();
     }
   }
 
@@ -423,7 +424,8 @@ class FocusNode with DiagnosticableTreeMixin, ChangeNotifier {
       if (!_canRequestFocus) {
         unfocus();
       }
-      _notify();
+      _manager?._dirtyNodes?.add(this);
+      _manager?._markNeedsUpdate();
     }
   }
 

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

@@ -345,7 +345,7 @@ class _ShortcutsState extends State<Shortcuts> {
   @override
   Widget build(BuildContext context) {
     return Focus(
-      skipTraversal: true,
+      canRequestFocus: false,
       onKey: _handleOnKey,
       child: _ShortcutsMarker(
         manager: manager,

packages/flutter/test/material/chip_test.dart

@@ -1837,4 +1837,71 @@ void main() {
     // Teardown.
     await gesture.removePointer();
   });
+
+  testWidgets('loses focus when disabled', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode(debugLabel: 'InputChip');
+    await tester.pumpWidget(
+      _wrapForChip(
+        child: InputChip(
+          focusNode: focusNode,
+          autofocus: true,
+          shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(0.0))),
+          avatar: const CircleAvatar(child: Text('A')),
+          label: const Text('Chip A'),
+          onPressed: () { },
+        ),
+      ),
+    );
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isTrue);
+
+    await tester.pumpWidget(
+      _wrapForChip(
+        child: InputChip(
+          focusNode: focusNode,
+          autofocus: true,
+          shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(0.0))),
+          avatar: const CircleAvatar(child: Text('A')),
+          label: const Text('Chip A'),
+          onPressed: null,
+        ),
+      ),
+    );
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isFalse);
+  });
+
+  testWidgets('cannot be traversed to when disabled', (WidgetTester tester) async {
+    final FocusNode focusNode1 = FocusNode(debugLabel: 'InputChip 1');
+    final FocusNode focusNode2 = FocusNode(debugLabel: 'InputChip 2');
+    await tester.pumpWidget(
+      _wrapForChip(
+        child: Column(
+          children: <Widget>[
+            InputChip(
+              focusNode: focusNode1,
+              autofocus: true,
+              label: const Text('Chip A'),
+              onPressed: () { },
+            ),
+            InputChip(
+              focusNode: focusNode2,
+              autofocus: true,
+              label: const Text('Chip B'),
+              onPressed: null,
+            ),
+          ],
+        ),
+      ),
+    );
+    await tester.pump();
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+
+    expect(focusNode1.nextFocus(), isTrue);
+
+    await tester.pump();
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+  });
 }

packages/flutter/test/material/icon_button_test.dart

@@ -332,13 +332,81 @@ void main() {
 
     semantics.dispose();
   });
+
+  testWidgets('IconButton loses focus when disabled.', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode(debugLabel: 'IconButton');
+    await tester.pumpWidget(
+      wrap(
+        child: IconButton(
+          focusNode: focusNode,
+          autofocus: true,
+          onPressed: () {},
+          icon: const Icon(Icons.link),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isTrue);
+
+    await tester.pumpWidget(
+      wrap(
+        child: IconButton(
+          focusNode: focusNode,
+          autofocus: true,
+          onPressed: null,
+          icon: const Icon(Icons.link),
+        ),
+      ),
+    );
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isFalse);
+  });
+
+  testWidgets("Disabled IconButton can't be traversed to when disabled.", (WidgetTester tester) async {
+    final FocusNode focusNode1 = FocusNode(debugLabel: 'IconButton 1');
+    final FocusNode focusNode2 = FocusNode(debugLabel: 'IconButton 2');
+
+    await tester.pumpWidget(
+      wrap(
+        child: Column(
+          children: <Widget>[
+            IconButton(
+              focusNode: focusNode1,
+              autofocus: true,
+              onPressed: () {},
+              icon: const Icon(Icons.link),
+            ),
+            IconButton(
+              focusNode: focusNode2,
+              onPressed: null,
+              icon: const Icon(Icons.link),
+            ),
+          ],
+        ),
+      ),
+    );
+    await tester.pump();
+
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+
+    expect(focusNode1.nextFocus(), isTrue);
+    await tester.pump();
+
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+  });
 }
 
 Widget wrap({ Widget child }) {
-  return Directionality(
-    textDirection: TextDirection.ltr,
-    child: Material(
-      child: Center(child: child),
+  return DefaultFocusTraversal(
+    policy: ReadingOrderTraversalPolicy(),
+    child: Directionality(
+      textDirection: TextDirection.ltr,
+      child: Material(
+        child: Center(child: child),
+      ),
     ),
   );
 }

packages/flutter/test/material/raw_material_button_test.dart

@@ -237,6 +237,78 @@ void main() {
     expect(box, paints..rect(color: focusColor));
   });
 
+  testWidgets('$RawMaterialButton loses focus when disabled.', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode(debugLabel: 'RawMaterialButton');
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Center(
+          child: RawMaterialButton(
+            autofocus: true,
+            focusNode: focusNode,
+            onPressed: () {},
+            child: Container(width: 100, height: 100, color: const Color(0xffff0000)),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isTrue);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Center(
+          child: RawMaterialButton(
+            focusNode: focusNode,
+            onPressed: null,
+            child: Container(width: 100, height: 100, color: const Color(0xffff0000)),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isFalse);
+  });
+
+  testWidgets("Disabled $RawMaterialButton can't be traversed to when disabled.", (WidgetTester tester) async {
+    final FocusNode focusNode1 = FocusNode(debugLabel: '$RawMaterialButton 1');
+    final FocusNode focusNode2 = FocusNode(debugLabel: '$RawMaterialButton 2');
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Center(
+          child: Column(
+            children: <Widget>[
+              RawMaterialButton(
+                autofocus: true,
+                focusNode: focusNode1,
+                onPressed: () {},
+                child: Container(width: 100, height: 100, color: const Color(0xffff0000)),
+              ),
+              RawMaterialButton(
+                autofocus: true,
+                focusNode: focusNode2,
+                onPressed: null,
+                child: Container(width: 100, height: 100, color: const Color(0xffff0000)),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+    await tester.pump();
+
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+
+    expect(focusNode1.nextFocus(), isTrue);
+    await tester.pump();
+
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+  });
+
   testWidgets('$RawMaterialButton handles hover', (WidgetTester tester) async {
     const Key key = Key('test');
     const Color hoverColor = Color(0xff00ff00);

packages/flutter/test/material/text_field_test.dart

@@ -3391,6 +3391,83 @@ void main() {
     semantics.dispose();
   });
 
+  testWidgets('TextField loses focus when disabled', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode(debugLabel: 'TextField');
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Center(
+            child: TextField(
+              focusNode: focusNode,
+              autofocus: true,
+              maxLength: 10,
+              enabled: true,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isTrue);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Center(
+            child: TextField(
+              focusNode: focusNode,
+              autofocus: true,
+              maxLength: 10,
+              enabled: false,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode.hasPrimaryFocus, isFalse);
+  });
+
+  testWidgets("Disabled TextField can't be traversed to when disabled.", (WidgetTester tester) async {
+    final FocusNode focusNode1 = FocusNode(debugLabel: 'TextField 1');
+    final FocusNode focusNode2 = FocusNode(debugLabel: 'TextField 2');
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Center(
+            child: Column(
+              children: <Widget>[
+                TextField(
+                  focusNode: focusNode1,
+                  autofocus: true,
+                  maxLength: 10,
+                  enabled: true,
+                ),
+                TextField(
+                  focusNode: focusNode2,
+                  maxLength: 10,
+                  enabled: false,
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+
+    expect(focusNode1.nextFocus(), isTrue);
+    await tester.pump();
+
+    expect(focusNode1.hasPrimaryFocus, isTrue);
+    expect(focusNode2.hasPrimaryFocus, isFalse);
+  });
+
   void sendFakeKeyEvent(Map<String, dynamic> data) {
     ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.keyEvent.name,

packages/flutter/test/material/text_form_field_test.dart

@@ -184,36 +184,11 @@ void main() {
     );
 
     expect(_validateCalled, 1);
-    await tester.showKeyboard(find.byType(TextField));
     await tester.enterText(find.byType(TextField), 'a');
     await tester.pump();
     expect(_validateCalled, 2);
   });
 
-  testWidgets('validate is not called if widget is disabled', (WidgetTester tester) async {
-    int _validateCalled = 0;
-
-    await tester.pumpWidget(
-      MaterialApp(
-        home: Material(
-          child: Center(
-            child: TextFormField(
-              enabled: false,
-              autovalidate: true,
-              validator: (String value) { _validateCalled += 1; return null; },
-            ),
-          ),
-        ),
-      ),
-    );
-
-    expect(_validateCalled, 0);
-    await tester.showKeyboard(find.byType(TextField));
-    await tester.enterText(find.byType(TextField), 'a');
-    await tester.pump();
-    expect(_validateCalled, 0);
-  });
-
   testWidgets('validate is called if widget is enabled', (WidgetTester tester) async {
     int _validateCalled = 0;
 
@@ -232,7 +207,6 @@ void main() {
     );
 
     expect(_validateCalled, 1);
-    await tester.showKeyboard(find.byType(TextField));
     await tester.enterText(find.byType(TextField), 'a');
     await tester.pump();
     expect(_validateCalled, 2);