Flutter如何在GestureDetector中部分阻止触摸事件

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('Partial Touch Event Handling'),
        ),
        body: Center(
          child: PartialTouchWidget(),
        ),
      ),
    );
  }
}

class PartialTouchWidget extends StatefulWidget {
  @override
  _PartialTouchWidgetState createState() => _PartialTouchWidgetState();
}

class _PartialTouchWidgetState extends State<PartialTouchWidget> {
  String _message = 'Touch inside the allowed area';

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTapDown: (TapDownDetails details) {
        // 获取触摸事件的位置
        Offset position = details.localPosition;

        // 定义允许触摸的区域
        Rect allowedArea = Rect.fromLTWH(50, 50, 200, 200);

        if (allowedArea.contains(position)) {
          setState(() {
            _message = 'Touched inside the allowed area';
          });
        } else {
          setState(() {
            _message = 'Touched outside the allowed area';
          });
        }
      },
      child: Container(
        width: 300,
        height: 300,
        color: Colors.blueAccent,
        child: Stack(
          children: [
            Positioned(
              left: 50,
              top: 50,
              width: 200,
              height: 200,
              child: Container(
                color: Colors.green.withOpacity(0.5),
              ),
            ),
            Center(
              child: Text(
                _message,
                style: TextStyle(color: Colors.white, fontSize: 16),
                textAlign: TextAlign.center,
              ),
            ),
          ],
        ),
      ),
    );
  }
}