如何将 ListWheelScrollView 定位到给定的索引？

Question

我想将 ListWheelScrollView 定位到随机给定的索引。 在定位时，旋转动画也必须工作。 如何定位到给定的索引？

编辑：它就像老虎机一样。

Answer 1

您可以在下面复制粘贴运行完整代码
您可以使用 FixedExtentScrollController 并调用 animateToItem
代码片段

final FixedExtentScrollController _controller = FixedExtentScrollController();
...
body: Center(
        child: ListWheelScrollView(
          controller: _controller,
          itemExtent: 80,
          magnification: 1.2,
          useMagnifier: true,
          physics: FixedExtentScrollPhysics(),
          children: listtiles, //List of widgets
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          _controller.animateToItem(random.nextInt(10),
              duration: Duration(milliseconds: 500), curve: Curves.linear);
        },
        child: Icon(Icons.add),
        backgroundColor: Colors.green,
      ),

工作演示

完整代码

import 'package:flutter/material.dart';
import 'dart:math';

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: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final FixedExtentScrollController _controller = FixedExtentScrollController();
  Random random = Random();

  List<Widget> listtiles = [
    GestureDetector(
      onTap: () {
        print("clicked 1");
      },
      child: ListTile(
        leading: Icon(Icons.portrait),
        title: Text("Portrait"),
        subtitle: Text("Beautiful View..!"),
        trailing: Icon(Icons.arrow_forward_ios),
      ),
    ),
    GestureDetector(
      onTap: () {
        print("clicked 2");
      },
      child: ListTile(
        leading: Icon(Icons.landscape),
        title: Text("LandScape"),
        subtitle: Text("Beautiful View..!"),
        trailing: Icon(Icons.remove),
      ),
    ),
    GestureDetector(
      onTap: () {
        print("clicked 3");
      },
      child: ListTile(
        leading: Icon(Icons.map),
        title: Text("Map"),
        subtitle: Text("Map View..!"),
        trailing: Icon(Icons.wb_sunny),
      ),
    ),
    ListTile(
      leading: Icon(Icons.landscape),
      title: Text("LandScape"),
      subtitle: Text("Wonderful View..!"),
      trailing: Icon(Icons.wb_sunny),
    ),
    ListTile(
      leading: Icon(Icons.list),
      title: Text("List Example"),
      subtitle: Text("List Wheel Scroll view .!"),
      trailing: Icon(Icons.cloud),
    ),
    ListTile(
      leading: Icon(Icons.settings),
      title: Text("Settings"),
      subtitle: Text("Change the setting..!"),
      trailing: Icon(Icons.portrait),
    ),
    ListTile(
      leading: Icon(Icons.event),
      title: Text("Add data"),
      subtitle: Text("Data View..!"),
      trailing: Icon(Icons.add),
    ),
    ListTile(
      leading: Icon(Icons.landscape),
      title: Text("LandScape"),
      subtitle: Text("Beautiful View..!"),
      trailing: Icon(Icons.wb_sunny),
    ),
    ListTile(
      leading: Icon(Icons.email),
      title: Text("Email"),
      subtitle: Text("Check Email..!"),
      trailing: Icon(Icons.arrow_forward),
    ),
    ListTile(
      leading: Icon(Icons.games),
      title: Text("Games"),
      subtitle: Text("Play Games..!"),
      trailing: Icon(Icons.zoom_out_map),
    ),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("ListView ScrollView Wheel"),
      ),
      body: Center(
        child: ListWheelScrollView(
          controller: _controller,
          itemExtent: 80,
          magnification: 1.2,
          useMagnifier: true,
          physics: FixedExtentScrollPhysics(),
          children: listtiles, //List of widgets
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          _controller.animateToItem(random.nextInt(10),
              duration: Duration(milliseconds: 500), curve: Curves.linear);
        },
        child: Icon(Icons.add),
        backgroundColor: Colors.green,
      ),
    );
  }
}