Created
September 6, 2023 11:04
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DebouncedScrollController
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| class DebouncedScrollController extends ScrollController { | |
| DebouncedScrollController({ | |
| super.initialScrollOffset, | |
| super.keepScrollOffset, | |
| super.debugLabel, | |
| super.onAttach, | |
| super.onDetach, | |
| this.debounceTime = const Duration(milliseconds: 150), | |
| }) { | |
| _streamSubscription = _streamController.stream | |
| .debounceTime(debounceTime) | |
| .listen(((event) => _listeners.forEach((listener) => listener()))); | |
| super.addListener(_onScroll); | |
| } | |
| /// The time for debouncing scroll events. | |
| /// | |
| /// Default value is `Duration(milliseconds: 150)`. | |
| final Duration debounceTime; | |
| final _streamController = StreamController<ScrollPosition>.broadcast(); | |
| late final StreamSubscription<ScrollPosition> _streamSubscription; | |
| List<VoidCallback> _listeners = <VoidCallback>[]; | |
| @override | |
| bool get hasListeners => _listeners.isNotEmpty; | |
| @override | |
| void addListener(VoidCallback listener) => _listeners.add(listener); | |
| @override | |
| void removeListener(VoidCallback listener) => _listeners.remove(listener); | |
| void resumeNotification() => _streamSubscription.resume(); | |
| void pauseNotification() => _streamSubscription.pause(); | |
| void _onScroll() { | |
| if (hasClients) { | |
| _streamController.add(position); | |
| } | |
| } | |
| @override | |
| void dispose() { | |
| _streamSubscription.cancel(); | |
| _streamController.close(); | |
| _listeners = []; | |
| super.dispose(); | |
| } | |
| @override | |
| String toString() { | |
| final List<String> description = <String>[]; | |
| debugFillDescription(description); | |
| return '${describeIdentity(this)}(${description.join(", ")})'; | |
| } | |
| @override | |
| void debugFillDescription(List<String> description) { | |
| if (debounceTime.inMicroseconds > 0) { | |
| description.add('debounceTime: $debounceTime'); | |
| } | |
| super.debugFillDescription(description); | |
| } | |
| } |
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