Flutter - 重启 CountdownTimer

Question

我有一个倒数计时器（5 分钟）。我需要一些东西来重新开始这个倒计时并从头开始。

我尝试更改倒计时变量的状态但不起作用，停止并从计数器的最后一个数字重新启动。

我的代码：

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

    class ProgressIndicatorDemo extends StatefulWidget {
      @override
      _ProgressIndicatorDemoState createState() =>
          new _ProgressIndicatorDemoState();
    }

    class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
        with SingleTickerProviderStateMixin {
      AnimationController controller;
      Animation<double> animation;
      var countdown;
      int actual;

      @override
      void initState() {
        super.initState();
        animationStart();
        startTimer();
      }

      @override
      void dispose() {
        controller.dispose();
        super.dispose();
      }

      void animationStart() {
        controller =
            AnimationController(duration: Duration(minutes: 5), vsync: this);
        animation = Tween(begin: 0.0, end: 1.0).animate(controller)
          ..addListener(() {
            setState(() {});
          });
        controller.forward();
      }

      void startTimer() {
        CountdownTimer countDownTimer = new CountdownTimer(
          new Duration(minutes: 5),
          new Duration(seconds: 1),
        );

        countdown = countDownTimer.listen(null);
        countdown.onData((duration) {
          setState(() {
            actual = 300 - duration.elapsed.inSeconds;
          });
        });

        countdown.onDone(() {
          countdown.cancel();
        });
      }

      @override
      Widget build(BuildContext context) {
        return new Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: <Widget>[
              animation.value != 1.0
                  ? CircularProgressIndicator(
                      semanticsLabel:
                          (animation.value * 100.0).toStringAsFixed(1).toString() +
                              '%',
                      semanticsValue:
                          (animation.value * 100.0).toStringAsFixed(1).toString() +
                              '%',
                      backgroundColor: Colors.black.withOpacity(0.25),
                      valueColor:
                          new AlwaysStoppedAnimation<Color>(Colors.green[700]),
                      value: animation.value)
                  : Icon(Icons.info_outline),
              actual != null
                  ? Text(
                      "Tiempo:" +
                          DateFormat.ms()
                              .format(DateTime.fromMillisecondsSinceEpoch(
                                  actual * 1000))
                              .toString(),
                      textAlign: TextAlign.center,
                    )
                  : Container(),
              FlatButton(
                  child: Text('Reset ' + actual.toString()), onPressed: () {}),
            ],
          ),
        );
      }
    }

所以问题是：我怎样才能从开始倒计时重新开始？

Answer 1

尝试先取消计时器并再次启动计时器：

  void restartTimer() {
    countDownTimer.cancel();
    startTimer();
  }

Answer 2

您可以使用更清洁的解决方案 RestartableTimer

import 'package:async/async.dart';

RestartableTimer _timer = new RestartableTimer(_timerDuration, _startNewPage);

然后您可以通过简单地调用重新开始倒计时 _timer.reset();

希望能帮助到你。