如何在Flutter中获取网格视图索引？

class MyGridView extends StatefulWidget {
  @override
  _MyGridViewState createState() => _MyGridViewState();
}

class _MyGridViewState extends State<MyGridView> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Grid View'),
      ),
      body: GridView.builder(
        itemCount: 20, // 网格项的数量
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 2, // 每行显示的网格数量
        ),
        itemBuilder: (BuildContext context, int index) {
          return GestureDetector(
            onTap: () {
              // 处理网格项的点击事件
              print('Tapped on grid item $index');
            },
            child: GridTile(
              child: Container(
                color: Colors.blue,
                child: Center(
                  child: Text(
                    'Item $index',
                    style: TextStyle(
                      color: Colors.white,
                      fontSize: 20.0,
                    ),
                  ),
                ),
              ),
            ),
          );
        },
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyGridView(),
  ));
}