Flutter-创建倒数计时小部件

Flutter-创建倒数计时小部件

听起来您正在尝试显示随时间变化的动画文本小部件。我将使用

AnimatedWidget

与

StepTween

来确保倒数仅显示整数值。

import 'package:flutter/material.dart';void main() {  runApp(new MaterialApp(    home: new MyApp(),  ));}class Countdown extends AnimatedWidget {  Countdown({ Key key, this.animation }) : super(key: key, listenable: animation);  Animation<int> animation;  @override  build(BuildContext context){    return new Text(      animation.value.toString(),      style: new TextStyle(fontSize: 150.0),    );  }}class MyApp extends StatefulWidget {  State createState() => new _MyAppState();}class _MyAppState extends State<MyApp> with TickerProviderStateMixin {  AnimationController _controller;  static const int kStartValue = 4;  @override  void initState() {    super.initState();    _controller = new AnimationController(      vsync: this,      duration: new Duration(seconds: kStartValue),    );  }  @override  Widget build(BuildContext context) {    return new Scaffold(      floatingActionButton: new FloatingActionButton(        child: new Icon(Icons.play_arrow),        onPressed: () => _controller.forward(from: 0.0),      ),      body: new Container(        child: new Center(          child: new Countdown( animation: new StepTween(   begin: kStartValue,   end: 0, ).animate(_controller),          ),        ),      ),    );  }}