Created
September 6, 2023 09:24
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ScrollableDebouce
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| class ScrollableDebounce extends StatefulWidget { | |
| const ScrollableDebounce({ | |
| Key? key, | |
| required this.controller, | |
| required this.onScroll, | |
| this.debounceTime = const Duration(milliseconds: 200), | |
| required this.child, | |
| }) : super(key: key); | |
| /// An object that can be used to control the position to which this scroll | |
| /// view is scrolled. | |
| final ScrollController controller; | |
| /// The time for debouncing scroll events. | |
| /// | |
| /// Default value is `Duration(milliseconds: 200)`. | |
| final Duration debounceTime; | |
| /// Callback on debounced scroll event. | |
| final void Function(ScrollPosition scrollPosition) onScroll; | |
| /// The widget below this widget in the tree. | |
| /// | |
| /// {@template flutter.widgets.ProxyWidget.child} | |
| /// This widget can only have one child. To lay out multiple children, let this | |
| /// widget's child be a widget such as [Row], [Column], or [Stack], which have a | |
| /// `children` property, and then provide the children to that widget. | |
| /// {@endtemplate} | |
| final Widget child; | |
| @override | |
| State<ScrollableDebounce> createState() => _ScrollableDebounceState(); | |
| } | |
| class _ScrollableDebounceState extends State<ScrollableDebounce> { | |
| final _streamController = StreamController<ScrollPosition>.broadcast(); | |
| late final StreamSubscription<ScrollPosition> _streamSubscription; | |
| @override | |
| void dispose() { | |
| widget.controller.removeListener(_onScroll); | |
| _streamSubscription.cancel(); | |
| _streamController.close(); | |
| super.dispose(); | |
| } | |
| @override | |
| void initState() { | |
| super.initState(); | |
| _streamSubscription = _streamController.stream | |
| .debounceTime(widget.debounceTime) | |
| .listen(widget.onScroll); | |
| widget.controller.addListener(_onScroll); | |
| } | |
| @override | |
| void didUpdateWidget(covariant ScrollableDebounce oldWidget) { | |
| super.didUpdateWidget(oldWidget); | |
| if (widget.controller != oldWidget.controller) { | |
| widget.controller.addListener(_onScroll); | |
| oldWidget.controller.removeListener(_onScroll); | |
| } | |
| } | |
| @override | |
| Widget build(BuildContext context) { | |
| return widget.child; | |
| } | |
| void _onScroll() { | |
| if (widget.controller.hasClients) { | |
| _streamController.add(widget.controller.position); | |
| } | |
| } | |
| } |
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