3

我有带有PageView小部件的简单页面，里面有ListView. 滚动PageView不起作用的地方。原因很简单。因为嵌套子级消耗的指针事件。

  @override
  Widget build(BuildContext context) {
    setupController();

    return PageView(
      controller: controllerPage,
      scrollDirection: Axis.vertical,
      children: <Widget>[
          ListView.builder(
            controller: controller,
            padding: EdgeInsets.all(AppDimens.bounds),
            itemCount: 15,
            itemBuilder: (context, index){
              return Container(
                height: 100,
                color: index %2 == 0 
                    ? Colors.amber : Colors.blueAccent,
              );
            },
          ),
        Container(color: Colors.green),
        Container(color: Colors.blue),
      ],
    );
  }

我的问题是有什么理智的方法可以让它一起工作吗？您可能会看到 的 垂直轴，但使用和PageView的水平轴会出现完全相同的问题。PageViewListView

到目前为止我尝试了什么？我有一些解决方法。即使它并不复杂，只是感觉不太好和笨重。通过使用AbsorbPointer和自定义控制器进行滚动。

  final controller = ScrollController();
  final controllerPage = PageController(keepPage: true);
  bool hasNestedScroll = true;

  void setupController() {
    controller.addListener(() {

      if (controller.offset + 5 > controller.position.maxScrollExtent &&
          !controller.position.outOfRange) {
        /// Swap to Inactive, if it was not
        if (hasNestedScroll) {
          setState(() {
            hasNestedScroll = false;
          });
        }
      } else {
        /// Swap to Active, if it was not
        if (!hasNestedScroll) {
          setState(() {
            hasNestedScroll = true;
          });
        }
      }
    });

    controllerPage.addListener(() {
      if (controllerPage.page == 0) {
        setState(() {
          hasNestedScroll = true;
        });
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    setupController();

    return PageView(
      controller: controllerPage,
      scrollDirection: Axis.vertical,
      children: <Widget>[
        AbsorbPointer(
          absorbing: !hasNestedScroll,
          child: ListView.builder(
            controller: controller,
            padding: EdgeInsets.all(AppDimens.bounds),
            itemCount: 15,
            itemBuilder: (context, index){
              return Container(
                height: 100,
                color: index %2 == 0
                    ? Colors.amber : Colors.blueAccent,
              );
            },
          ),
        ),
        Container(color: Colors.green),
        Container(color: Colors.blue),
      ],
    );
  }
4

2 回答 2

3

我最近陷入了类似的情况，经过一些研究和阅读有关手势如何在颤动中工作的内容后，我找到了一个足够好的工作解决方案。所以我使用了 RawGestureDetector，它为您提供了一个低级的手势小部件处理，并通过将 PageView 和 ListView 设置physics为NeverScrollableScrollPhysics. 这意味着使用它们各自的控制器滚动这些小部件 -PageViewController和ScrollController. 现在根据 ListView 的位置和状态，使用控制器选择并拖动两者中的一个活动控制器。主类看起来像这样。

void main() => runApp(App());

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: Scaffold(appBar: AppBar(), body: NestedContainerWidget()));
  }
}

class NestedContainerWidget extends StatefulWidget {
  @override
  _NestedContainerWidgetState createState() => _NestedContainerWidgetState();
}

class _NestedContainerWidgetState extends State<NestedContainerWidget> {
  PageController _pageController;
  ScrollController _listScrollController;
  ScrollController _activeScrollController;
  Drag _drag;

  @override
  void initState() {
    super.initState();
    _pageController = PageController();
    _listScrollController = ScrollController();
  }

  @override
  void dispose() {
    _pageController.dispose();
    _listScrollController.dispose();
    super.dispose();
  }

  void _handleDragStart(DragStartDetails details) {
    if (_listScrollController.hasClients &&
        _listScrollController.position.context.storageContext != null) {
      final RenderBox renderBox =
          _listScrollController.position.context.storageContext.findRenderObject();
      if (renderBox.paintBounds
          .shift(renderBox.localToGlobal(Offset.zero))
          .contains(details.globalPosition)) {
        _activeScrollController = _listScrollController;
        _drag = _activeScrollController.position.drag(details, _disposeDrag);
        return;
      }
    }
    _activeScrollController = _pageController;
    _drag = _pageController.position.drag(details, _disposeDrag);
  }

  void _handleDragUpdate(DragUpdateDetails details) {
    if (_activeScrollController == _listScrollController &&
        details.primaryDelta < 0 &&
        _activeScrollController.position.pixels ==
            _activeScrollController.position.maxScrollExtent) {
      _activeScrollController = _pageController;
      _drag?.cancel();
      _drag = _pageController.position.drag(
          DragStartDetails(
              globalPosition: details.globalPosition, localPosition: details.localPosition),
          _disposeDrag);
    }
    _drag?.update(details);
  }

  void _handleDragEnd(DragEndDetails details) {
    _drag?.end(details);
  }

  void _handleDragCancel() {
    _drag?.cancel();
  }

  void _disposeDrag() {
    _drag = null;
  }

  @override
  Widget build(BuildContext context) {
    return RawGestureDetector(
      gestures: <Type, GestureRecognizerFactory>{
        VerticalDragGestureRecognizer:
            GestureRecognizerFactoryWithHandlers<VerticalDragGestureRecognizer>(
                () => VerticalDragGestureRecognizer(), (VerticalDragGestureRecognizer instance) {
          instance
            ..onStart = _handleDragStart
            ..onUpdate = _handleDragUpdate
            ..onEnd = _handleDragEnd
            ..onCancel = _handleDragCancel;
        })
      },
      behavior: HitTestBehavior.opaque,
      child: PageView(
        controller: _pageController,
        scrollDirection: Axis.vertical,
        physics: const NeverScrollableScrollPhysics(),
        children: [
          Center(child: Text('Page 1')),
          ListView(
            controller: _listScrollController,
            physics: const NeverScrollableScrollPhysics(),
            children: List.generate(
              20,
              (int index) {
                return ListTile(title: Text('Item $index'));
              },
            ),
          ),
        ],
      ),
    );
  }
}

查看其中的逻辑，_handleDragStart它_handleDragUpdate根据小部件的状态及其滚动状态确定应该滚动的控制器ListView。

我写了一篇关于这个问题的详细文章，你可以在这里查看 - https://medium.com/@Mak95/nested-scrolling-listview-inside-pageview-in-flutter-a57b7a6241b1

该解决方案可以改进，因此非常欢迎输入。

于 2020-07-18T19:36:02.363 回答
1

我用这个答案来帮助我解决同样的问题。

基本上，你听可滚动的孩子OverscrollNotification使用NotificationListener并使用其控制器滚动父母。

代码：

final pageCntrler = PageController();

_scrollDown() async {
  await pageCntrler.nextPage(
    duration: scrollDuration,
    curve: scrollCurve,
  );
}

_scrollUp() async {
  await pageCntrler.previousPage(
    duration: scrollDuration,
    curve: scrollCurve,
  );
}

@override
Widget build(BuildContext context) {
  return PageView(
    controller: pageCntrler,
    scrollDirection: Axis.vertical,
    physics: NeverScrollableScrollPhysics(),
    children: [
      NotificationListener(
        onNotification: (notification) {
          if (notification is OverscrollNotification) {
            if (notification.overscroll > 0) {
              _scrollDown();
            } else {
              _scrollUp();
            }
          }
        },
        child: SingleChildScrollView(),
      )
    ],
  );
}
于 2021-01-29T19:50:05.293 回答