[CupertinoActionSheet] Add haptic feedback (flutter#151420)

This PR implements the behavior of native action sheets that produces haptic feedback when the user slides into a button.

Author: dkwingsmt

packages/flutter/lib/src/cupertino/dialog.dart

@@ -14,6 +14,7 @@ import 'dart:ui' show ImageFilter, lerpDouble;
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
 import 'colors.dart';
@@ -595,7 +596,10 @@ abstract class _ActionSheetSlideTarget {
   //  * The point has contacted the screen in this region. In this case, this
   //    method is called as soon as the pointer down event occurs regardless of
   //    whether the gesture wins the arena immediately.
-  void didEnter();
+  //
+  // The `fromPointerDown` should be true if this callback is triggered by a
+  // PointerDownEvent, i.e. the second case from the list above.
+  void didEnter({required bool fromPointerDown});
 
   // A pointer has exited this region.
   //
@@ -660,7 +664,10 @@ class _TargetSelectionGestureRecognizer extends GestureRecognizer {
   // Collect the `_ActionSheetSlideTarget`s that are currently hit by the
   // pointer, check whether the current target have changed, and invoke their
   // methods if necessary.
-  void _updateDrag(Offset pointerPosition) {
+  //
+  // The `fromPointerDown` should be true if this update is triggered by a
+  // PointerDownEvent.
+  void _updateDrag(Offset pointerPosition, {required bool fromPointerDown}) {
     final HitTestResult result = hitTest(pointerPosition);
 
     // A slide target might nest other targets, therefore multiple targets might
@@ -686,21 +693,21 @@ class _TargetSelectionGestureRecognizer extends GestureRecognizer {
         ..clear()
         ..addAll(foundTargets);
       for (final _ActionSheetSlideTarget target in _currentTargets) {
-        target.didEnter();
+        target.didEnter(fromPointerDown: fromPointerDown);
       }
     }
   }
 
   void _onDown(DragDownDetails details) {
-    _updateDrag(details.globalPosition);
+    _updateDrag(details.globalPosition, fromPointerDown: true);
   }
 
   void _onUpdate(Offset globalPosition) {
-    _updateDrag(globalPosition);
+    _updateDrag(globalPosition, fromPointerDown: false);
   }
 
   void _onEnd(Offset globalPosition) {
-    _updateDrag(globalPosition);
+    _updateDrag(globalPosition, fromPointerDown: false);
     for (final _ActionSheetSlideTarget target in _currentTargets) {
       target.didConfirm();
     }
@@ -1121,7 +1128,7 @@ class _CupertinoActionSheetActionState extends State<CupertinoActionSheetAction>
     implements _ActionSheetSlideTarget {
   // |_ActionSheetSlideTarget|
   @override
-  void didEnter() {}
+  void didEnter({required bool fromPointerDown}) {}
 
   // |_ActionSheetSlideTarget|
   @override
@@ -1243,11 +1250,27 @@ class _ActionSheetButtonBackground extends StatefulWidget {
 class _ActionSheetButtonBackgroundState extends State<_ActionSheetButtonBackground> implements _ActionSheetSlideTarget {
   bool isBeingPressed = false;
 
+  void _emitVibration(){
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.iOS:
+      case TargetPlatform.android:
+        HapticFeedback.selectionClick();
+      case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.macOS:
+      case TargetPlatform.windows:
+        break;
+    }
+  }
+
   // |_ActionSheetSlideTarget|
   @override
-  void didEnter() {
+  void didEnter({required bool fromPointerDown}) {
     setState(() { isBeingPressed = true; });
     widget.onPressStateChange?.call(true);
+    if (!fromPointerDown) {
+      _emitVibration();
+    }
   }
 
   // |_ActionSheetSlideTarget|

packages/flutter/test/cupertino/action_sheet_test.dart

@@ -12,6 +12,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
 
 import 'package:flutter_test/flutter_test.dart';
 
@@ -1900,6 +1901,50 @@ void main() {
       kIsWeb ? SystemMouseCursors.click : SystemMouseCursors.basic,
     );
   });
+
+  testWidgets('Action sheets emits haptic vibration on sliding into a button', (WidgetTester tester) async {
+    int vibrationCount = 0;
+
+    tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+      if (methodCall.method == 'HapticFeedback.vibrate') {
+        expect(methodCall.arguments, 'HapticFeedbackType.selectionClick');
+        vibrationCount += 1;
+      }
+      return null;
+    });
+
+    await tester.pumpWidget(
+      createAppWithButtonThatLaunchesActionSheet(
+        CupertinoActionSheet(
+            title: const Text('The title'),
+            actions: <Widget>[
+              CupertinoActionSheetAction(child: const Text('One'), onPressed: () {}),
+              CupertinoActionSheetAction(child: const Text('Two'), onPressed: () {}),
+              CupertinoActionSheetAction(child: const Text('Three'), onPressed: () {}),
+            ],
+          )
+        ),
+    );
+
+    await tester.tap(find.text('Go'));
+    await tester.pumpAndSettle();
+
+    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.text('One')));
+    await tester.pumpAndSettle();
+    // Tapping down on a button should not emit vibration.
+    expect(vibrationCount, 0);
+
+    await gesture.moveTo(tester.getCenter(find.text('Two')));
+    await tester.pumpAndSettle();
+    expect(vibrationCount, 1);
+
+    await gesture.moveTo(tester.getCenter(find.text('Three')));
+    await tester.pumpAndSettle();
+    expect(vibrationCount, 2);
+
+    await gesture.up();
+    expect(vibrationCount, 2);
+  }, variant: TargetPlatformVariant.only(TargetPlatform.iOS));
 }
 
 RenderBox findScrollableActionsSectionRenderBox(WidgetTester tester) {