在AnimatedSize的父部件添加动画控制器并在onPressed方法中调用控制器的forward方法，以便启动AnimatedSize的缓动动画。

示例代码：

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State with TickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );
  }

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

  @override
  Widget build(BuildContext context) {
    return InkWell(
      child: AnimatedSize(
        duration: Duration(seconds: 1),
        vsync: this,
        child: Text('Hello, world!'),
      ),
      onTap: () {
        _controller.forward();
      },
    );
  }
}