Add PrioritizedIntents to support multiple shortcut configurations (#72560)

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

@@ -1321,3 +1321,50 @@ class DismissIntent extends Intent {
 ///
 /// This is an abstract class that serves as a base class for dismiss actions.
 abstract class DismissAction extends Action<DismissIntent> {}
+
+/// An [Intent] that evaluates a series of specified [orderedIntents] for
+/// execution.
+class PrioritizedIntents extends Intent {
+  /// Creates a set of const [PrioritizedIntents].
+  const PrioritizedIntents({
+    required this.orderedIntents,
+  })  : assert(orderedIntents != null);
+
+  /// List of intents to be evaluated in order for execution. When an
+  /// [Action.isEnabled] returns true, that action will be invoked and
+  /// progression through the ordered intents stops.
+  final List<Intent> orderedIntents;
+}
+
+/// An [Action] that iterates through a list of [Intent]s, invoking the first
+/// that is enabled.
+class PrioritizedAction extends Action<PrioritizedIntents> {
+  late Action<dynamic> _selectedAction;
+  late Intent _selectedIntent;
+
+  @override
+  bool isEnabled(PrioritizedIntents intent) {
+    final FocusNode? focus = primaryFocus;
+    if  (focus == null || focus.context == null)
+      return false;
+    for (final Intent candidateIntent in intent.orderedIntents) {
+      final Action<Intent>? candidateAction = Actions.maybeFind<Intent>(
+        focus.context!,
+        intent: candidateIntent,
+      );
+      if (candidateAction != null && candidateAction.isEnabled(candidateIntent)) {
+        _selectedAction = candidateAction;
+        _selectedIntent = candidateIntent;
+        return true;
+      }
+    }
+    return false;
+  }
+
+  @override
+  Object? invoke(PrioritizedIntents intent) {
+    assert(_selectedAction != null);
+    assert(_selectedIntent != null);
+    _selectedAction.invoke(_selectedIntent);
+  }
+}

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

@@ -1024,7 +1024,12 @@ class WidgetsApp extends StatefulWidget {
   // Default shortcuts for the web platform.
   static final Map<LogicalKeySet, Intent> _defaultWebShortcuts = <LogicalKeySet, Intent>{
     // Activation
-    LogicalKeySet(LogicalKeyboardKey.space): const ActivateIntent(),
+    LogicalKeySet(LogicalKeyboardKey.space): const PrioritizedIntents(
+      orderedIntents: <Intent>[
+        ActivateIntent(),
+        ScrollIntent(direction: AxisDirection.down, type: ScrollIncrementType.page),
+      ]
+    ),
     // On the web, enter activates buttons, but not other controls.
     LogicalKeySet(LogicalKeyboardKey.enter): const ButtonActivateIntent(),
 
@@ -1100,6 +1105,7 @@ class WidgetsApp extends StatefulWidget {
     PreviousFocusIntent: PreviousFocusAction(),
     DirectionalFocusIntent: DirectionalFocusAction(),
     ScrollIntent: ScrollAction(),
+    PrioritizedIntents: PrioritizedAction(),
   };
 
   @override

packages/flutter/test/widgets/shortcuts_test.dart

@@ -579,5 +579,86 @@ void main() {
       expect(description[0], equalsIgnoringHashCodes('manager: ShortcutManager#00000(shortcuts: {})'));
       expect(description[1], equalsIgnoringHashCodes('shortcuts: {{Key A + Key B}: ActivateIntent#00000}'));
     });
+
+    testWidgets('Shortcuts support multiple intents', (WidgetTester tester) async {
+      tester.binding.focusManager.highlightStrategy = FocusHighlightStrategy.alwaysTraditional;
+      bool? value = true;
+      Widget buildApp() {
+        return MaterialApp(
+          shortcuts: <LogicalKeySet, Intent>{
+            LogicalKeySet(LogicalKeyboardKey.space): const PrioritizedIntents(
+              orderedIntents: <Intent>[
+                ActivateIntent(),
+                ScrollIntent(direction: AxisDirection.down, type: ScrollIncrementType.page),
+              ]
+            ),
+            LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
+            LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(direction: AxisDirection.up, type: ScrollIncrementType.page),
+          },
+          home: Material(
+            child: Center(
+              child: ListView(
+                primary: true,
+                children: <Widget> [
+                  StatefulBuilder(
+                    builder: (BuildContext context, StateSetter setState) {
+                      return Checkbox(
+                        value: value,
+                        onChanged: (bool? newValue) => setState(() { value = newValue; }),
+                        focusColor: Colors.orange[500],
+                      );
+                    },
+                  ),
+                  Container(
+                    color: Colors.blue,
+                    height: 1000,
+                  )
+                ],
+              ),
+            ),
+          ),
+        );
+      }
+      await tester.pumpWidget(buildApp());
+      await tester.pumpAndSettle();
+      expect(
+        tester.binding.focusManager.primaryFocus!.toStringShort(),
+        equalsIgnoringHashCodes('FocusScopeNode#00000(_ModalScopeState<dynamic> Focus Scope [PRIMARY FOCUS])'),
+      );
+      final ScrollController controller = PrimaryScrollController.of(
+        tester.element(find.byType(ListView))
+      )!;
+      expect(controller.position.pixels, 0.0);
+      expect(value, isTrue);
+
+      await tester.sendKeyEvent(LogicalKeyboardKey.space);
+      await tester.pumpAndSettle();
+      // ScrollView scrolls
+      expect(controller.position.pixels, 448.0);
+      expect(value, isTrue);
+
+      await tester.sendKeyEvent(LogicalKeyboardKey.pageUp);
+      await tester.pumpAndSettle();
+      await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+      await tester.pumpAndSettle();
+      // Focus is now on the checkbox.
+      expect(
+        tester.binding.focusManager.primaryFocus!.toStringShort(),
+        equalsIgnoringHashCodes('FocusNode#00000([PRIMARY FOCUS])'),
+      );
+      expect(value, isTrue);
+      expect(controller.position.pixels, 0.0);
+
+      await tester.sendKeyEvent(LogicalKeyboardKey.space);
+      await tester.pumpAndSettle();
+      // Checkbox is toggled, scroll view does not scroll.
+      expect(value, isFalse);
+      expect(controller.position.pixels, 0.0);
+
+      await tester.sendKeyEvent(LogicalKeyboardKey.space);
+      await tester.pumpAndSettle();
+      expect(value, isTrue);
+      expect(controller.position.pixels, 0.0);
+    });
   });
 }