Flutter -自定义绘画动画从屏幕上消失

class MyAnimatedWidget extends StatefulWidget {
  @override
  _MyAnimatedWidgetState createState() => _MyAnimatedWidgetState();
}

class _MyAnimatedWidgetState extends State<MyAnimatedWidget> with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 2),
      vsync: this,
    );
    _animation = Tween<double>(begin: 1.0, end: 0.0).animate(_controller);
    _controller.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _animation,
      builder: (context, child) {
        return CustomPaint(
          painter: MyCustomPainter(_animation.value),
          size: Size(double.infinity, double.infinity),
        );
      },
    );
  }
}

class MyCustomPainter extends CustomPainter {
  final double opacity;

  MyCustomPainter(this.opacity);

  @override
  void paint(Canvas canvas, Size size) {
    // 使用opacity绘制内容
  }

  @override
  bool shouldRepaint(MyCustomPainter oldDelegate) {
    return oldDelegate.opacity != opacity;
  }
}

class MyAnimatedWidget extends StatefulWidget {
  @override
  _MyAnimatedWidgetState createState() => _MyAnimatedWidgetState();
}

class _MyAnimatedWidgetState extends State<MyAnimatedWidget> with SingleTickerProviderStateMixin {
  // ... 其他代码保持不变

  @override
  Widget build(BuildContext context) {
    return const AnimatedBuilder(
      animation: _animation,
      builder: (context, child) {
        return CustomPaint(
          painter: MyCustomPainter(_animation.value),
          size: Size(double.infinity, double.infinity),
        );
      },
    );
  }
}

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