android - 在 Flutter 中如何让 PageView 滚动得更快？动画似乎很慢，内部 ListView 无法响应我的垂直手势

Question

您可以在 video 中查看详细信息

这个问题我不知道怎么解决。和Android Native ViewPager相比，Flutter中PageView的动画似乎要慢一些，用户只需要等待这个慢动画完全停止，就可以拖动内部的ListView了。我感觉用户体验比原生android ViewPager差。希望完美解决。

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_app/reactive_page_view/reactive_page_view.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Page(),
    );
  }
}

class Page extends StatefulWidget {
  @override
  _PageState createState() => _PageState();
}

PageView view;

class _PageState extends State<Page> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: CupertinoNavigationBar(
        middle: Text("Demo"),
      ),
      body: PageView.builder(
          physics: BouncingScrollPhysics(),
          itemCount: 3,
          itemBuilder: (context, index) {
            return ItemPage();
          }),
    );
  }
}

class ItemPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
        physics: BouncingScrollPhysics(),
        itemCount: 30,
        itemBuilder: (context, index) {
          return Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text('这是第$index', style: TextStyle(fontSize: 30)),
          );
        });
  }
}

Answer 1

您可以定义自己的 PageController 实例并使用其方法 nextPage() 和 previousPage()。他们有控制页面 View 滚动速度的“持续时间”参数。

final PageController controller = PageController(
    viewportFraction: 0.9,
  );

  void nextPage() async {
    await controller.nextPage(
      duration: Duration(milliseconds: 200),
      curve: Curves.easeOut,
    );
  }

  void prevPage() async {
    await controller.previousPage(
      duration: Duration(milliseconds: 200),
      curve: Curves.easeOut,
    );
  }

然后将此 Controller 应用于您的页面 View :

return PageView.builder(
      physics: NeverScrollableScrollPhysics(),
      controller: controller,
      ...
    );

main.dart 的完整代码:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyPageViewExample(),
    );
  }
}

class MyPageViewExample extends StatelessWidget {
  MyPageViewExample({Key key}) : super(key: key);

  final PageController controller = PageController(
    viewportFraction: 0.9,
  );

  void nextPage() async {
    await controller.nextPage(
      duration: Duration(milliseconds: 200),
      curve: Curves.easeOut,
    );
  }

  void prevPage() async {
    await controller.previousPage(
      duration: Duration(milliseconds: 200),
      curve: Curves.easeOut,
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: <Widget>[
          Container(
            color: Colors.grey[100],
          ),
          Padding(
            padding: EdgeInsets.only(top: 20.0 + MediaQuery.of(context).padding.top, bottom: 20.0),
            child: _buildCarousel(context),
          ),
        ],
      ),
    );
  }

  Widget _buildCarousel(BuildContext context) {
    return PageView.builder(
      physics: NeverScrollableScrollPhysics(),
      controller: controller,
      scrollDirection: Axis.horizontal,
      itemBuilder: (BuildContext context, int itemIndex) {
        return _buildItem(context, itemIndex);
      },
      itemCount: 5,
    );
  }

  Widget _buildItem(BuildContext context, int itemIndex) {
    return Padding(
      padding: EdgeInsets.only(left: 4.0, top: 10.0, right: 4.0, bottom: 10.0),
      child: GestureDetector(
        onPanUpdate: (details) {
          if (details.delta.dx < 0) {
            nextPage();
          }
          if (details.delta.dx > 0) {
            prevPage();
          }
        },
        child: Container(
          decoration: BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.all(Radius.circular(35.0)),
          ),
          child: Center(
            child: Text(
              'Item ' + (itemIndex + 1).toString(),
            ),
          ),
        ),
      ),
    );
  }
}