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Trigger CupertinoPicker haptics in the middle of the item #169670

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Trigger CupertinoPicker haptics in the middle of the item #169670

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acbca70
trigger haptics in the middle
RepliedSage11 May 29, 2025
8cd1956
Merge branch 'master' into picker_haptics
RepliedSage11 Jun 2, 2025
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56 changes: 38 additions & 18 deletions packages/flutter/lib/src/cupertino/picker.dart
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -219,12 +219,16 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
int? _lastHapticIndex;
FixedExtentScrollController? _controller;

FixedExtentScrollController get _effectiveController => widget.scrollController ?? _controller!;

@override
void initState() {
super.initState();
if (widget.scrollController == null) {
_controller = FixedExtentScrollController();
}

_effectiveController.addListener(_handleScroll);
}

@override
Expand All @@ -233,42 +237,59 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
if (widget.scrollController != null && oldWidget.scrollController == null) {
_controller?.dispose();
_controller = null;
widget.scrollController!.addListener(_handleScroll);
} else if (widget.scrollController == null && oldWidget.scrollController != null) {
assert(_controller == null);
oldWidget.scrollController!.removeListener(_handleScroll);
_controller = FixedExtentScrollController();
_controller!.addListener(_handleScroll);
}
}

@override
void dispose() {
_controller?.dispose();
if (widget.scrollController != null) {
widget.scrollController!.removeListener(_handleScroll);
}
super.dispose();
}

void _handleSelectedItemChanged(int index) {
// Only the haptic engine hardware on iOS devices would produce the
// intended effects.
final bool hasSuitableHapticHardware;
void _handleHapticFeedback(int index) {
// Skip haptic feedback on the first item.
if (_lastHapticIndex == null) {
_lastHapticIndex = index;
return;
}
switch (defaultTargetPlatform) {
case TargetPlatform.iOS:
hasSuitableHapticHardware = true;
if (index != _lastHapticIndex) {
_lastHapticIndex = index;
HapticFeedback.selectionClick();
}
case TargetPlatform.android:
case TargetPlatform.fuchsia:
case TargetPlatform.linux:
case TargetPlatform.macOS:
case TargetPlatform.windows:
hasSuitableHapticHardware = false;
}
if (hasSuitableHapticHardware && index != _lastHapticIndex) {
_lastHapticIndex = index;
HapticFeedback.selectionClick();
// No haptic feedback on these platforms.
return;
}
}

widget.onSelectedItemChanged?.call(index);
void _handleScroll() {
final int index = _effectiveController.selectedItem;

final double currentItemOffset = _effectiveController.offset / widget.itemExtent - index;
// Check if the current scroll offset is passing through the center point of an item
// This happens when the fractional part is very close to 0.0.
if (currentItemOffset.abs() <= 0.1) {
_handleHapticFeedback(index);
}
}

void _handleChildTap(int index, FixedExtentScrollController controller) {
controller.animateToItem(
void _handleChildTap(int index) {
_effectiveController.animateToItem(
index,
duration: _kCupertinoPickerTapToScrollDuration,
curve: _kCupertinoPickerTapToScrollCurve,
Expand Down Expand Up @@ -298,7 +319,6 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
);

assert(RenderListWheelViewport.defaultPerspective == _kDefaultPerspective);
final FixedExtentScrollController controller = widget.scrollController ?? _controller!;
final Widget result = DefaultTextStyle(
style: textStyle.copyWith(
color: CupertinoDynamicColor.maybeResolve(textStyle.color, context),
Expand All @@ -307,9 +327,9 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
children: <Widget>[
Positioned.fill(
child: _CupertinoPickerSemantics(
scrollController: controller,
scrollController: _effectiveController,
child: ListWheelScrollView.useDelegate(
controller: controller,
controller: _effectiveController,
physics: const FixedExtentScrollPhysics(),
diameterRatio: widget.diameterRatio,
offAxisFraction: widget.offAxisFraction,
Expand All @@ -318,11 +338,11 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
overAndUnderCenterOpacity: _kOverAndUnderCenterOpacity,
itemExtent: widget.itemExtent,
squeeze: widget.squeeze,
onSelectedItemChanged: _handleSelectedItemChanged,
onSelectedItemChanged: widget.onSelectedItemChanged,
dragStartBehavior: DragStartBehavior.down,
childDelegate: _CupertinoPickerListWheelChildDelegateWrapper(
widget.childDelegate,
onTappedChild: (int index) => _handleChildTap(index, controller),
onTappedChild: _handleChildTap,
),
),
),
Expand Down
19 changes: 15 additions & 4 deletions packages/flutter/test/cupertino/picker_test.dart
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -272,7 +272,7 @@ void main() {

group('scroll', () {
testWidgets(
'scrolling calls onSelectedItemChanged and triggers haptic feedback',
'scrolling calls onSelectedItemChanged and triggers haptic feedback when scroll passes middle of item',
(WidgetTester tester) async {
final List<int> selectedItems = <int>[];
final List<MethodCall> systemCalls = <MethodCall>[];
Expand Down Expand Up @@ -300,21 +300,28 @@ void main() {
),
),
);

// Drag to almost the middle of the next item.
await tester.drag(
find.text('0'),
const Offset(0.0, -100.0),
const Offset(0.0, -90.0),
warnIfMissed: false,
); // has an IgnorePointer
// Expect that the item changed, but haptics were not triggered yet,
// since we are not in the middle of the item.
expect(selectedItems, <int>[1]);
expect(systemCalls, isEmpty);

// Let the scroll settle and end up in the middle of the item.
await tester.pumpAndSettle();
expect(
systemCalls.single,
isMethodCall('HapticFeedback.vibrate', arguments: 'HapticFeedbackType.selectionClick'),
);

// Overscroll a little to pass the middle of the item.
await tester.drag(
find.text('0'),
const Offset(0.0, 100.0),
const Offset(0.0, 110.0),
warnIfMissed: false,
); // has an IgnorePointer
expect(selectedItems, <int>[1, 0]);
Expand Down Expand Up @@ -362,6 +369,10 @@ void main() {
const Offset(0.0, -100.0),
warnIfMissed: false,
); // has an IgnorePointer

// Allow the scroll to settle in the middle of the item.
await tester.pumpAndSettle();

expect(selectedItems, <int>[1]);
expect(systemCalls, isEmpty);
},
Expand Down