如何配置Flutter的showModalBottomSheet打开/关闭动画？

import 'package:flutter/material.dart';

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

class _MyWidgetState extends State<MyWidget> with SingleTickerProviderStateMixin {
  AnimationController _animationController;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(
      vsync: this,
      duration: Duration(milliseconds: 300), // 设置动画的持续时间
    );
    _animation = CurvedAnimation(
      parent: _animationController,
      curve: Curves.easeInOut, // 设置动画的曲线
    );
  }

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

  void _openModalBottomSheet() {
    _animationController.forward(); // 播放打开动画
    showModalBottomSheet(
      context: context,
      builder: (BuildContext context) {
        return AnimatedBuilder(
          animation: _animation,
          builder: (BuildContext context, Widget child) {
            return Transform.translate(
              offset: Offset(0.0, _animation.value * MediaQuery.of(context).size.height),
              child: Container(
                height: 200.0,
                color: Colors.white,
                child: Center(
                  child: Text('Modal Bottom Sheet'),
                ),
              ),
            );
          },
        );
      },
    );
  }

  void _closeModalBottomSheet() {
    _animationController.reverse(); // 播放关闭动画
    Navigator.pop(context);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Modal Bottom Sheet'),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: _openModalBottomSheet,
          child: Text('Open Modal Bottom Sheet'),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _closeModalBottomSheet,
        child: Icon(Icons.close),
      ),
    );
  }
}