如何在flutter的水平列表视图中将屏幕上选定的项目居中？

import 'package:flutter/material.dart';

class MyList extends StatefulWidget {
  @override
  _MyListState createState() => _MyListState();
}

class _MyListState extends State<MyList> {
  ScrollController _controller = ScrollController();
  int _selectedIndex = 0;

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      scrollDirection: Axis.horizontal,
      controller: _controller,
      itemCount: 10,
      itemBuilder: (context, index) {
        return GestureDetector(
          onTap: () {
            setState(() {
              _selectedIndex = index;
              _scrollToSelectedIndex();
            });
          },
          child: Container(
            width: 100,
            height: 100,
            color: _selectedIndex == index ? Colors.blue : Colors.grey,
            child: Center(
              child: Text(
                'Item $index',
                style: TextStyle(color: Colors.white),
              ),
            ),
          ),
        );
      },
    );
  }

  void _scrollToSelectedIndex() {
    double offset = (_selectedIndex * 100) - (MediaQuery.of(context).size.width / 2);
    _controller.animateTo(
      offset,
      duration: Duration(milliseconds: 500),
      curve: Curves.ease,
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(title: Text('Centered ListView')),
      body: Center(child: MyList()),
    ),
  ));
}