66 lines
2.1 KiB
Dart
66 lines
2.1 KiB
Dart
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import 'package:wonders/common_libs.dart';
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/// Decouples the scrollable area from the size of the PageView itself.
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/// Helps simplify the layout of the underlying view and can create a better UX with screen-readers.
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///
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/// Internally it creates a stack with an invisible PageView on the bottom to handle scrolling,
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/// then drives a second PageController (follower) which is passed to the `builder` so a nested PageView can
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/// be created to hold the content itself.
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///
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/// Scrolling of the nested PageView will then be driven by the outer one.
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///
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class StackedPageViewBuilder extends StatefulWidget {
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const StackedPageViewBuilder({
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Key? key,
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this.initialIndex = 0,
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required this.pageCount,
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required this.builder,
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this.onInit,
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}) : super(key: key);
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final int initialIndex;
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final int pageCount;
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final Widget Function(BuildContext builder, PageController controller, PageController follower) builder;
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final void Function(PageController controller, PageController follower)? onInit;
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@override
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State<StackedPageViewBuilder> createState() => _StackedPageViewBuilderState();
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}
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class _StackedPageViewBuilderState extends State<StackedPageViewBuilder> {
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late final _controller = PageController(initialPage: widget.initialIndex);
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late final _follower = PageController(initialPage: widget.initialIndex);
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@override
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void initState() {
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super.initState();
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_controller.addListener(_handleControllerChanged);
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widget.onInit?.call(_controller, _follower);
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}
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@override
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void dispose() {
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_controller.dispose();
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_follower.dispose();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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return Stack(
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children: [
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Positioned.fill(
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child: ExcludeSemantics(
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child: PageView.builder(
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itemCount: widget.pageCount,
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controller: _controller,
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itemBuilder: (_, __) => Container(color: Colors.transparent),
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),
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),
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),
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widget.builder(context, _controller, _follower),
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],
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);
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}
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void _handleControllerChanged() => _follower.jumpTo(_controller.position.pixels);
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}
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