Flutter动画和运动控件之位置变化PositionedTransition

late AnimationController _controller = AnimationController(
  duration: const Duration(seconds: 2),
  vsync: this,
)..repeat(reverse: true);

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

@override
Widget build(BuildContext context) {
  final double smallLogo = 100;
  final double bigLogo = 200;

  return LayoutBuilder(
    builder: (context, constraints) {
      final Size biggest = constraints.biggest;
      return Stack(
        children: [
          PositionedTransition(
            rect: RelativeRectTween(
              begin: RelativeRect.fromSize(Rect.fromLTWH(0, 0, smallLogo, smallLogo), biggest),
              end: RelativeRect.fromSize(Rect.fromLTWH(biggest.width - bigLogo, biggest.height - bigLogo, bigLogo, bigLogo), biggest),
            ).animate(CurvedAnimation(
              parent: _controller,
              curve: Curves.elasticInOut,
            )),
            child: Padding(
              padding: const EdgeInsets.all(8),
              child: FlutterLogo()
            ),
          ),
        ],
      );
    },
  );
}