如何在抖动中显示动画图像

Question

在我的应用中，我想代表掷骰子。 当前，当我掷骰子时，它随机移动到六个图像之一，没有任何动画。 我想要的只是显示动画场景，六个骰子之间需要2秒的移动时间，就像骰子在滚动一样。 我尝试使用notification true，但是只有当我单击按钮时，它才能工作，setState()中有一种使用setState()的方式，这是我的状态类

loop

摘要：

我有一个按钮和六个图像，当我单击按钮时，我希望连续显示图像。

包裹是什么？我应该怎么做？

Answer 1

结合CountdownTimer和AnimatedSwitcher，可以看到图片的效果
对于演示，我只使用3张图片，完整代码请参见下面的

代码段

AnimatedSwitcher(
          child: Image(
              image: AssetImage('assets/images/${elapsed}.png'),
              key: ValueKey(elapsed)),
          duration: Duration(seconds: 1),
        ),
...
final cd = CountdownTimer(Duration(seconds: 3), Duration(seconds: 1));
    cd.listen((data) {
      setState(() {
        elapsed = cd.elapsed.inSeconds;
        print(elapsed);
      });
    }, onDone: () {
      cd.cancel();
    });

完整代码

import 'package:flutter/material.dart';
import 'package:quiver/async.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(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  int elapsed = 1;

  void _incrementCounter() {

    final cd = CountdownTimer(Duration(seconds: 3), Duration(seconds: 1));
    cd.listen((data) {
      setState(() {
        elapsed = cd.elapsed.inSeconds;
        print(elapsed);
      });
    }, onDone: () {
      cd.cancel();
    });

  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            AnimatedSwitcher(
              child: Image(
                  image: AssetImage('assets/images/${elapsed}.png'),
                  key: ValueKey(elapsed)),
              duration: Duration(seconds: 1),
            ),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

Answer 2

您需要在函数或小部件构建中添加 _controller.repeat();