在 Flutter 倒计时期间向倒计时计时器添加时间

Question

我正在尝试创建一个倒数计时器应用程序，在该应用程序中，我可以在计时器主动倒计时时按下一个按钮来增加更多时间，就像每个微波炉一样，您可以按下一个按钮来增加一分钟运行时间运行没有停止任何东西。

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),
          ),
        ),
      ),
    );
  }
}

这个关于计时器的类似问题的例子对我来说很有意义，并且是我的出发点。我知道我需要更改持续时间并用具有适当持续时间的新动画替换动画，但我从来没有得到任何接近我正在寻找的正确行为的东西。

Answer 1

我认为以下是您要实现的目标。点击 FloatingActionButton 添加 5 秒。

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Countdown Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Countdown Demo'),
    );
  }
}

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _timeRemaining = 10;
  Timer _timer;

  @override
  void initState() {
    _timer = Timer.periodic(Duration(seconds: 1), (Timer t) => _getTime());
    super.initState();
  }

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Text('$_timeRemaining'),
      ),
      floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {
            _timeRemaining += 5;
          }),
    );
  }

  void _getTime() {
    setState(() {
      _timeRemaining == 0 ? _timeRemaining = 0 : _timeRemaining--;
    });
  }
}

在 Flutter 倒计时期间向倒计时计时器添加时间

Add time to countdown timer during while counting down in Flutter

dart

flutter

flutter-animation