Flutter使用stack实现悬浮UI的示例代码

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('Floating UI Example'),
        ),
        body: MyFloatingUI(),
      ),
    );
  }
}

class MyFloatingUI extends StatefulWidget {
  @override
  _MyFloatingUIState createState() => _MyFloatingUIState();
}

class _MyFloatingUIState extends State<MyFloatingUI> {
  bool isFloatingUIVisible = false;

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        // Your main content goes here
        Center(
          child: Text(
            'Main Content',
            style: TextStyle(fontSize: 20),
          ),
        ),
        
        // Floating UI
        Visibility(
          visible: isFloatingUIVisible,
          child: Positioned(
            bottom: 16,
            right: 16,
            child: FloatingActionButton(
              onPressed: () {
                // Handle floating button tap
                print('Floating Button Tapped');
              },
              child: Icon(Icons.add),
            ),
          ),
        ),
      ],
    );
  }

  // Show/hide the floating UI based on some condition
  void toggleFloatingUI() {
    setState(() {
      isFloatingUIVisible = !isFloatingUIVisible;
    });
  }
}