Question

我想传递一个值来将动画的起始值设置为1.0，而不是从0开始，但是我不知道该如何实现。

class AnimatedIconButton extends StatefulWidget {
  AnimatedIconButton(this.img, this.start);
  final String img;
  final double start;
  @override
  _AnimatedIconButtonState createState() => _AnimatedIconButtonState();
}

class _AnimatedIconButtonState extends State<AnimatedIconButton>
    with TickerProviderStateMixin {
  AnimationController _controller;
  Animation _animation;

  void animateButton() {
    if (_animation.value == 0)
      _controller.forward();
    else
      _controller.reverse();
  }

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(milliseconds: 300),
      vsync: this,
    );
    _animation =
        CurvedAnimation(parent: _controller, curve: Curves.easeOutQuad);
    _controller.addListener(() {
      setState(() {});
    });
    _animation.value = widget.start;// does not work
  }

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

  @override
  Widget build(BuildContext context) {
    return MaterialButton(
      splashColor: Colors.white,
      highlightColor: Colors.white,
      child: Image.asset("images/${widget.img}.png",
          width: 33 + (16 * _animation.value)),
      onPressed: () {
        animateButton();
      },
    );
  }
}

Answer 1

您可以使用：

a0acb90300000000
Lets add some spaces and capitalize letters:
A0 AC B9 03 00 00 00 00


62500000
Windows calculator converts to:
3B9ACA0
This is a number from a calculator, lets add spaces right to left
3 B9 AC A0
Lets add some zeros to the left side, we have:
00 00 00 00 03 B9 AC A0
Before:
A0 AC B9 03 00 00 00 00

或

_controller.forward(from: 0.0);

并设置所需的值

或者您可以使用设置初始值

_controller.reverse(from: 1.0);

Answer 2

在您的代码内：

添加_controller.forward(1.0);。

您可以在此处传递所需的值。

像下面这样：

void animateButton() {
  if (_animation.value == 0)
    _controller.forward(from: 1.0);
  else
    _controller.reverse(from: 1.0);
}

Answer 3

据我了解，您要使动画从1.0开始而不是从0.0开始所以这里是..

设置全局变量，例如：-

<div>
  <label>Wafer Type:</label>
  <select name="s1">
    <option value="1"> First </option>
    <option value="2"> Second </option>
  </select>
</div>
<input type="text" name="lotNo" />

覆盖initState方法：-

Animation<double> animation;
AnimationController controller;
Tween<double> tween = Tween(begin: 0, end: 100);

最后，您可以通过以下方法更改开始和结束动画值：-

@override
void initState() {
super.initState();
controller=AnimationController(vsync: this, duration: Duration(seconds: 2));
animation = tween.animate(controller);
}

Answer 4

如果您想使用forward()将反向驱动值的动画，即1.0 → 0.0，最简单的解决方案是使用ReverseAnimation：

  @override
  void initState() {
    super.initState();
    _animationController =
        AnimationController(vsync: this, duration: Duration(milliseconds: 500));
    _hideAnimation = ReverseAnimation(
      CurvedAnimation(
        parent: _animationController,
        curve: Curves.fastOutSlowIn,
      ),
    ),
  }

颤振设置开始动画值

4 个答案: