ModalBarrier and Drawer barrier prevents mouse events (#44296)

* Add opaque to barriers
* Detect opaque and test

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

@@ -546,9 +546,12 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
                   onTap: close,
                   child: Semantics(
                     label: MaterialLocalizations.of(context)?.modalBarrierDismissLabel,
-                    child: Container( // The drawer's "scrim"
-                      color: _scrimColorTween.evaluate(_controller),
-                    ),
+                    child: MouseRegion(
+                      opaque: true,
+                      child: Container( // The drawer's "scrim"
+                        color: _scrimColorTween.evaluate(_controller),
+                      ),
+                    )
                   ),
                 ),
               ),

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -2615,12 +2615,13 @@ class RenderMouseRegion extends RenderProxyBox {
     PointerEnterEventListener onEnter,
     PointerHoverEventListener onHover,
     PointerExitEventListener onExit,
-    this.opaque = true,
+    bool opaque = true,
     RenderBox child,
   }) : assert(opaque != null),
        _onEnter = onEnter,
        _onHover = onHover,
        _onExit = onExit,
+       _opaque = opaque,
        _annotationIsActive = false,
        super(child) {
     _hoverAnnotation = MouseTrackerAnnotation(
@@ -2644,7 +2645,14 @@ class RenderMouseRegion extends RenderProxyBox {
   /// pointer is within their areas.
   ///
   /// This defaults to true.
-  bool opaque;
+  bool get opaque => _opaque;
+  bool _opaque;
+  set opaque(bool value) {
+    if (_opaque != value) {
+      _opaque = value;
+      _updateAnnotations();
+    }
+  }
 
   /// Called when a mouse pointer enters the region (with or without buttons
   /// pressed).
@@ -2705,7 +2713,8 @@ class RenderMouseRegion extends RenderProxyBox {
     final bool annotationWillBeActive = (
         _onEnter != null ||
         _onHover != null ||
-        _onExit != null
+        _onExit != null ||
+        opaque
       ) &&
       RendererBinding.instance.mouseTracker.mouseIsConnected;
     if (annotationWasActive != annotationWillBeActive) {

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

@@ -101,11 +101,14 @@ class ModalBarrier extends StatelessWidget {
           child: Semantics(
             label: semanticsDismissible ? semanticsLabel : null,
             textDirection: semanticsDismissible && semanticsLabel != null ? Directionality.of(context) : null,
-            child: ConstrainedBox(
-              constraints: const BoxConstraints.expand(),
-              child: color == null ? null : DecoratedBox(
-                decoration: BoxDecoration(
-                  color: color,
+            child: MouseRegion(
+              opaque: true,
+              child: ConstrainedBox(
+                constraints: const BoxConstraints.expand(),
+                child: color == null ? null : DecoratedBox(
+                  decoration: BoxDecoration(
+                    color: color,
+                  ),
                 ),
               ),
             ),

packages/flutter/test/widgets/drawer_test.dart

@@ -78,6 +78,78 @@ void main() {
     expect(find.text('drawer'), findsNothing);
   });
 
+  testWidgets('Drawer hover test', (WidgetTester tester) async {
+    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
+    final List<String> logs = <String>[];
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    addTearDown(gesture.removePointer);
+
+    // Start out of hoverTarget
+    await gesture.moveTo(const Offset(100, 100));
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          key: scaffoldKey,
+          drawer: const Text('drawer'),
+          body: Align(
+            alignment: Alignment.topLeft,
+            child: MouseRegion(
+              onEnter: (_) { logs.add('enter'); },
+              onHover: (_) { logs.add('hover'); },
+              onExit: (_) { logs.add('exit'); },
+              child: Container(width: 10, height: 10),
+            ),
+          ),
+        ),
+      ),
+    );
+    expect(logs, isEmpty);
+    expect(find.text('drawer'), findsNothing);
+
+    // When drawer is closed, hover is interactable
+    await gesture.moveTo(const Offset(5, 5));
+    await tester.pump(); // no effect
+    expect(logs, <String>['enter', 'hover']);
+    logs.clear();
+
+    await gesture.moveTo(const Offset(20, 20));
+    await tester.pump(); // no effect
+    expect(logs, <String>['exit']);
+    logs.clear();
+
+    // When drawer is open, hover is uninteractable
+    scaffoldKey.currentState.openDrawer();
+    await tester.pump(const Duration(seconds: 1)); // animation done
+    expect(find.text('drawer'), findsOneWidget);
+
+    await gesture.moveTo(const Offset(5, 5));
+    await tester.pump(); // no effect
+    expect(logs, isEmpty);
+    logs.clear();
+
+    await gesture.moveTo(const Offset(20, 20));
+    await tester.pump(); // no effect
+    expect(logs, isEmpty);
+    logs.clear();
+
+    // Close drawer, hover is interactable again
+    await tester.tapAt(const Offset(750.0, 100.0)); // on the mask
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1)); // animation done
+    expect(find.text('drawer'), findsNothing);
+
+    await gesture.moveTo(const Offset(5, 5));
+    await tester.pump(); // no effect
+    expect(logs, <String>['enter', 'hover']);
+    logs.clear();
+
+    await gesture.moveTo(const Offset(20, 20));
+    await tester.pump(); // no effect
+    expect(logs, <String>['exit']);
+    logs.clear();
+  });
+
   testWidgets('Drawer drag cancel resume (LTR)', (WidgetTester tester) async {
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
     await tester.pumpWidget(
@@ -324,5 +396,3 @@ void main() {
     semantics.dispose();
   });
 }
-
-

packages/flutter/test/widgets/modal_barrier_test.dart

@@ -7,13 +7,15 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show kSecondaryButton;
+import 'package:flutter/gestures.dart' show kSecondaryButton, PointerDeviceKind;
 
 import 'semantics_tester.dart';
 
 void main() {
   bool tapped;
+  bool hovered;
   Widget tapTarget;
+  Widget hoverTarget;
 
   setUp(() {
     tapped = false;
@@ -27,6 +29,18 @@ void main() {
         child: Text('target', textDirection: TextDirection.ltr),
       ),
     );
+
+    hovered = false;
+    hoverTarget = MouseRegion(
+      onHover: (_) { hovered = true; },
+      onEnter: (_) { hovered = true; },
+      onExit: (_) { hovered = true; },
+      child: const SizedBox(
+        width: 10.0,
+        height: 10.0,
+        child: Text('target', textDirection: TextDirection.ltr),
+      ),
+    );
   });
 
   testWidgets('ModalBarrier prevents interactions with widgets behind it', (WidgetTester tester) async {
@@ -45,6 +59,35 @@ void main() {
       reason: 'because the tap is not prevented by ModalBarrier');
   });
 
+  testWidgets('ModalBarrier prevents hover interactions with widgets behind it', (WidgetTester tester) async {
+    final Widget subject = Stack(
+      textDirection: TextDirection.ltr,
+      children: <Widget>[
+        hoverTarget,
+        const ModalBarrier(dismissible: false),
+      ],
+    );
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    addTearDown(gesture.removePointer);
+    // Start out of hoverTarget
+    await gesture.moveTo(const Offset(100, 100));
+
+    await tester.pumpWidget(subject);
+    // Move into hoverTarget and tap
+    await gesture.down(const Offset(5, 5));
+    await tester.pumpWidget(subject);
+    await gesture.up();
+    await tester.pumpWidget(subject);
+
+    // Move out
+    await gesture.moveTo(const Offset(100, 100));
+    await tester.pumpWidget(subject);
+
+    expect(hovered, isFalse,
+      reason: 'because the hover is not prevented by ModalBarrier');
+  });
+
   testWidgets('ModalBarrier does not prevent interactions with widgets in front of it', (WidgetTester tester) async {
     final Widget subject = Stack(
       textDirection: TextDirection.ltr,
@@ -89,6 +132,37 @@ void main() {
       reason: 'because the drag is prevented by ModalBarrier');
   });
 
+  testWidgets('ModalBarrier does not prevent hover interactions with widgets in front of it', (WidgetTester tester) async {
+    final Widget subject = Stack(
+      textDirection: TextDirection.ltr,
+      children: <Widget>[
+        const ModalBarrier(dismissible: false),
+        hoverTarget,
+      ],
+    );
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    addTearDown(gesture.removePointer);
+    // Start out of hoverTarget
+    await gesture.moveTo(const Offset(100, 100));
+    await tester.pumpWidget(subject);
+    expect(hovered, isFalse);
+
+    // Move into hoverTarget
+    await gesture.moveTo(const Offset(5, 5));
+    await tester.pumpWidget(subject);
+    expect(hovered, isTrue,
+      reason: 'because the hover is prevented by ModalBarrier');
+    hovered = false;
+
+    // Move out
+    await gesture.moveTo(const Offset(100, 100));
+    await tester.pumpWidget(subject);
+    expect(hovered, isTrue,
+      reason: 'because the hover is prevented by ModalBarrier');
+    hovered = false;
+  });
+
   testWidgets('ModalBarrier pops the Navigator when dismissed by primay tap', (WidgetTester tester) async {
     final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
       '/': (BuildContext context) => FirstWidget(),

packages/flutter/test/widgets/mouse_region_test.dart

@@ -523,7 +523,7 @@ void main() {
     await tester.pumpWidget(
       Transform.scale(
         scale: 2.0,
-        child: const MouseRegion(),
+        child: const MouseRegion(opaque: false),
       ),
     );
     final RenderMouseRegion listener = tester.renderObject(find.byType(MouseRegion));
@@ -534,10 +534,12 @@ void main() {
     // transform.)
     expect(tester.layers.whereType<TransformLayer>(), hasLength(1));
 
+    // Test that needsCompositing updates correctly with callback change
     await tester.pumpWidget(
       Transform.scale(
         scale: 2.0,
         child: MouseRegion(
+          opaque: false,
           onHover: (PointerHoverEvent _) {},
         ),
       ),
@@ -550,13 +552,27 @@ void main() {
     await tester.pumpWidget(
       Transform.scale(
         scale: 2.0,
-        child: const MouseRegion(),
+        child: const MouseRegion(opaque: false),
       ),
     );
     expect(listener.needsCompositing, isFalse);
     // TransformLayer for `Transform.scale` is removed again as transform is
     // executed directly on the canvas.
     expect(tester.layers.whereType<TransformLayer>(), hasLength(1));
+
+    // Test that needsCompositing updates correctly with `opaque` change
+    await tester.pumpWidget(
+      Transform.scale(
+        scale: 2.0,
+        child: const MouseRegion(
+          opaque: true,
+        ),
+      ),
+    );
+    expect(listener.needsCompositing, isTrue);
+    // Compositing is required, therefore a dedicated TransformLayer for
+    // `Transform.scale` is added.
+    expect(tester.layers.whereType<TransformLayer>(), hasLength(2));
   });
 
   testWidgets("Callbacks aren't called during build", (WidgetTester tester) async {
@@ -942,6 +958,42 @@ void main() {
     });
   });
 
+  testWidgets('an empty opaque MouseRegion is effective', (WidgetTester tester) async {
+    bool bottomRegionIsHovered = false;
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: Stack(
+          children: <Widget>[
+            Align(
+              alignment: Alignment.topLeft,
+              child: MouseRegion(
+                  onEnter: (_) { bottomRegionIsHovered = true; },
+                  onHover: (_) { bottomRegionIsHovered = true; },
+                  onExit: (_) { bottomRegionIsHovered = true; },
+                  child: Container(
+                    width: 10,
+                    height: 10,
+                ),
+              ),
+            ),
+            const MouseRegion(opaque: true),
+          ],
+        ),
+      ),
+    );
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(20, 20));
+    addTearDown(gesture.removePointer);
+
+    await gesture.moveTo(const Offset(5, 5));
+    await tester.pump();
+    await gesture.moveTo(const Offset(20, 20));
+    await tester.pump();
+    expect(bottomRegionIsHovered, isFalse);
+  });
+
   testWidgets('RenderMouseRegion\'s debugFillProperties when default', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     RenderMouseRegion().debugFillProperties(builder);