animation - 您如何更改 didUpdateWidget 上 flutter 动画的持续时间？

Question

我想按需更新计时器，但我不知道如何去做。我想检查在更改持续时间之前更新小部件时是否满足某些条件。到目前为止，我已经尝试使用“didUpdateWidget”函数，但我收到了一个代码错误。当我将 mixin 更改为 TickerProviderStateMixin 时，持续时间不会更新。

class _ProgressBarState extends State<ProgressBar>
    with SingleTickerProviderStateMixin {

  int _duration;
  int _position;
  bool _isPaused;

  Animation animation;
  AnimationController animationController;

  @override
  void initState() {
    super.initState();
    _duration = widget.duration;
    _position = widget.position;
    _isPaused = widget.isPaused;
    animationController = AnimationController(
    duration: Duration(milliseconds: _duration), vsync: this);
    animation = Tween(begin: 0.0, end: 1.0).animate(animationController);
  }

  @override
    void didUpdateWidget(ProgressBar oldWidget) {
      // TODO: implement didUpdateWidget
      setState(() {
        _duration = widget.duration;
        _position = widget.position;
        _isPaused = widget.isPaused;
      });

      updateController(oldWidget);
      super.didUpdateWidget(oldWidget);
    }


  void updateController(ProgressBar oldWidget){
    if(oldWidget.duration != _duration){
      animationController.dispose();
      animationController = AnimationController(duration: Duration(milliseconds: _duration), vsync:this);
    }
    if(_isPaused){
      animationController.stop();
    } else{
        animationController.forward(from: _position/_duration);
      }
  }
//...
}

Answer 1

仔细看了文档，发现直接修改AnimationController的属性就可以了。哈哈...

animationController.duration = Duration(milliseconds: _duration)