Add HitTestBehavior to TapRegion (#113634)

Author: gspencergoog

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

@@ -173,7 +173,12 @@ abstract class RenderProxyBoxWithHitTestBehavior extends RenderProxyBox {
     RenderBox? child,
   }) : super(child);
 
-  /// How to behave during hit testing.
+  /// How to behave during hit testing when deciding how the hit test propagates
+  /// to children and whether to consider targets behind this one.
+  ///
+  /// Defaults to [HitTestBehavior.deferToChild].
+  ///
+  /// See [HitTestBehavior] for the allowed values and their meanings.
   HitTestBehavior behavior;
 
   @override

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

@@ -970,10 +970,14 @@ class GestureDetector extends StatelessWidget {
   /// detecting screens.
   final GestureForcePressEndCallback? onForcePressEnd;
 
-  /// How this gesture detector should behave during hit testing.
+  /// How this gesture detector should behave during hit testing when deciding
+  /// how the hit test propagates to children and whether to consider targets
+  /// behind this one.
   ///
   /// This defaults to [HitTestBehavior.deferToChild] if [child] is not null and
   /// [HitTestBehavior.translucent] if child is null.
+  ///
+  /// See [HitTestBehavior] for the allowed values and their meanings.
   final HitTestBehavior? behavior;
 
   /// Whether to exclude these gestures from the semantics tree. For

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

@@ -312,6 +312,7 @@ class TapRegion extends SingleChildRenderObjectWidget {
     super.key,
     required super.child,
     this.enabled = true,
+    this.behavior = HitTestBehavior.deferToChild,
     this.onTapOutside,
     this.onTapInside,
     this.groupId,
@@ -321,6 +322,14 @@ class TapRegion extends SingleChildRenderObjectWidget {
   /// Whether or not this [TapRegion] is enabled as part of the composite region.
   final bool enabled;
 
+  /// How to behave during hit testing when deciding how the hit test propagates
+  /// to children and whether to consider targets behind this [TapRegion].
+  ///
+  /// Defaults to [HitTestBehavior.deferToChild].
+  ///
+  /// See [HitTestBehavior] for the allowed values and their meanings.
+  final HitTestBehavior behavior;
+
   /// A callback to be invoked when a tap is detected outside of this
   /// [TapRegion] and any other region with the same [groupId], if any.
   ///
@@ -358,6 +367,7 @@ class TapRegion extends SingleChildRenderObjectWidget {
     return RenderTapRegion(
       registry: TapRegionRegistry.maybeOf(context),
       enabled: enabled,
+      behavior: behavior,
       onTapOutside: onTapOutside,
       onTapInside: onTapInside,
       groupId: groupId,
@@ -367,22 +377,25 @@ class TapRegion extends SingleChildRenderObjectWidget {
 
   @override
   void updateRenderObject(BuildContext context, covariant RenderTapRegion renderObject) {
-    renderObject.registry = TapRegionRegistry.maybeOf(context);
-    renderObject.enabled = enabled;
-    renderObject.groupId = groupId;
-    renderObject.onTapOutside = onTapOutside;
-    renderObject.onTapInside = onTapInside;
-    if (kReleaseMode) {
+    renderObject
+      ..registry = TapRegionRegistry.maybeOf(context)
+      ..enabled = enabled
+      ..behavior = behavior
+      ..groupId = groupId
+      ..onTapOutside = onTapOutside
+      ..onTapInside = onTapInside;
+    if (!kReleaseMode) {
       renderObject.debugLabel = debugLabel;
     }
   }
 
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
+    properties.add(FlagProperty('enabled', value: enabled, ifFalse: 'DISABLED', defaultValue: true));
+    properties.add(DiagnosticsProperty<HitTestBehavior>('behavior', behavior, defaultValue: HitTestBehavior.deferToChild));
     properties.add(DiagnosticsProperty<Object?>('debugLabel', debugLabel, defaultValue: null));
     properties.add(DiagnosticsProperty<Object?>('groupId', groupId, defaultValue: null));
-    properties.add(FlagProperty('enabled', value: enabled, ifFalse: 'DISABLED', defaultValue: true));
   }
 }
 
@@ -393,26 +406,33 @@ class TapRegion extends SingleChildRenderObjectWidget {
 /// system.
 ///
 /// This render object indicates to the nearest ancestor [TapRegionSurface] that
-/// the region occupied by its child will participate in the tap detection for
-/// that surface.
+/// the region occupied by its child (or itself if [behavior] is
+/// [HitTestBehavior.opaque]) will participate in the tap detection for that
+/// surface.
 ///
 /// If this region belongs to a group (by virtue of its [groupId]), all the
 /// regions in the group will act as one.
 ///
 /// If there is no [RenderTapRegionSurface] ancestor in the render tree,
 /// [RenderTapRegion] will do nothing.
 ///
+/// The [behavior] attribute describes how to behave during hit testing when
+/// deciding how the hit test propagates to children and whether to consider
+/// targets behind the tap region. Defaults to [HitTestBehavior.deferToChild].
+/// See [HitTestBehavior] for the allowed values and their meanings.
+///
 /// See also:
 ///
 ///  * [TapRegion], a widget that inserts a [RenderTapRegion] into the render
 ///    tree.
-class RenderTapRegion extends RenderProxyBox {
+class RenderTapRegion extends RenderProxyBoxWithHitTestBehavior {
   /// Creates a [RenderTapRegion].
   RenderTapRegion({
     TapRegionRegistry? registry,
     bool enabled = true,
     this.onTapOutside,
     this.onTapInside,
+    super.behavior = HitTestBehavior.deferToChild,
     Object? groupId,
     String? debugLabel,
   })  : _registry = registry,

packages/flutter/test/widgets/tap_region_test.dart

@@ -4,6 +4,7 @@
 
 import 'dart:ui';
 
+import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -99,6 +100,7 @@ void main() {
     await click(find.text('Outside Surface'));
     expect(tappedOutside, isEmpty);
   });
+
   testWidgets('TapRegionSurface detects inside taps', (WidgetTester tester) async {
     final Set<String> tappedInside = <String>{};
     await tester.pumpWidget(
@@ -185,6 +187,94 @@ void main() {
     await click(find.text('Outside Surface'));
     expect(tappedInside, isEmpty);
   });
+
+  testWidgets('TapRegionSurface detects inside taps correctly with behavior', (WidgetTester tester) async {
+    final Set<String> tappedInside = <String>{};
+    const ValueKey<String> noGroupKey = ValueKey<String>('No Group');
+    const ValueKey<String> group1AKey = ValueKey<String>('Group 1 A');
+    const ValueKey<String> group1BKey = ValueKey<String>('Group 1 B');
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: Column(
+          children: <Widget>[
+            const Text('Outside Surface'),
+            TapRegionSurface(
+              child: Row(
+                children: <Widget>[
+                  ConstrainedBox(
+                    constraints: const BoxConstraints.tightFor(width: 100, height: 100),
+                    child: TapRegion(
+                      // ignore: avoid_redundant_argument_values
+                      behavior: HitTestBehavior.deferToChild,
+                      onTapInside: (PointerEvent event) {
+                        tappedInside.add(noGroupKey.value);
+                      },
+                      child: Stack(key: noGroupKey),
+                    ),
+                  ),
+                  ConstrainedBox(
+                    constraints: const BoxConstraints.tightFor(width: 100, height: 100),
+                    child: TapRegion(
+                      groupId: 1,
+                      behavior: HitTestBehavior.opaque,
+                      onTapInside: (PointerEvent event) {
+                        tappedInside.add(group1AKey.value);
+                      },
+                      child: Stack(key: group1AKey),
+                    ),
+                  ),
+                  ConstrainedBox(
+                    constraints: const BoxConstraints.tightFor(width: 100, height: 100),
+                    child: TapRegion(
+                      groupId: 1,
+                      behavior: HitTestBehavior.translucent,
+                      onTapInside: (PointerEvent event) {
+                        tappedInside.add(group1BKey.value);
+                      },
+                      child: Stack(key: group1BKey),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+
+    await tester.pump();
+
+    Future<void> click(Finder finder) async {
+      final TestGesture gesture = await tester.startGesture(
+        tester.getCenter(finder),
+        kind: PointerDeviceKind.mouse,
+      );
+      await gesture.up();
+      await gesture.removePointer();
+    }
+
+    expect(tappedInside, isEmpty);
+
+    await click(find.byKey(noGroupKey));
+    expect(tappedInside, isEmpty); // No hittable children, so no hit.
+
+    await click(find.byKey(group1AKey));
+    // No hittable children, but set to opaque, so it hits, triggering the
+    // group.
+    expect(tappedInside,
+      equals(<String>{
+        'Group 1 A',
+        'Group 1 B',
+      }),
+    );
+    tappedInside.clear();
+
+    await click(find.byKey(group1BKey));
+    expect(tappedInside, isEmpty); // No hittable children while translucent, so no hit.
+    tappedInside.clear();
+  });
+
   testWidgets('Setting the group updates the registration', (WidgetTester tester) async {
     final Set<String> tappedOutside = <String>{};
     await tester.pumpWidget(