Flutter - GestureDetector onTapDown颜色更改

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('GestureDetector Example'),
        ),
        body: Center(
          child: MyButton(),
        ),
      ),
    );
  }
}

class MyButton extends StatefulWidget {
  @override
  _MyButtonState createState() => _MyButtonState();
}

class _MyButtonState extends State<MyButton> {
  Color _buttonColor = Colors.blue;

  void _changeColor(TapDownDetails details) {
    setState(() {
      _buttonColor = Colors.red;
    });
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTapDown: _changeColor,
      child: Container(
        width: 200,
        height: 50,
        color: _buttonColor,
        child: Center(
          child: Text(
            'Tap Me',
            style: TextStyle(
              color: Colors.white,
              fontSize: 20,
            ),
          ),
        ),
      ),
    );
  }
}