Flutter的Animation中Interval的用法

class _MyHomePageState1 extends State with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation _animationSize;
  Animation _animationColor;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
        vsync: this, duration: Duration(milliseconds: 3000));
    _controller.addListener(() {
      setState(() {});
    });
    _animationSize = Tween(begin: 50.0, end: 100.0).animate(
        CurvedAnimation(parent: _controller, curve: Interval(0.0, 0.5)));
    //动画执行范围[0.0~1.0]
//Interval(0.0, 0.5) 前面一半执行变大动画

    _animationColor = ColorTween(begin: Colors.blue, end: Colors.amber)
        .animate(CurvedAnimation(parent: _controller, curve: Interval(0.3, 1)));
//Interval(0.3, 1) 0.3开始，执行颜色变化动画
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: Center(
          child: InkWell(
            onTap: () {
              if (_controller.isDismissed) {
                _controller.forward();
              } else {
                _controller.reverse();
              }
            },
            child: Container(
              width: _animationSize.value,
              height: _animationSize.value,
              decoration: BoxDecoration(
                  shape: BoxShape.circle, color: _animationColor.value),
            ),
          ),
        ),
      ),
    );
  }

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