Flutter 仿探探卡片滑动效果（上下左右）

在Flutter中，你可以使用Stack和Positioned小部件来实现探探卡片的滑动效果。以下是一个简单的示例，展示了如何创建一个上下左右滑动的卡片效果：

import 'package:flutter/material.dart';
 
void main() => runApp(MyApp());
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: DraggableCard(),
        ),
      ),
    );
  }
}
 
class DraggableCard extends StatefulWidget {
  @override
  _DraggableCardState createState() => _DraggableCardState();
}
 
class _DraggableCardState extends State<DraggableCard> with TickerProviderStateMixin {
  AnimationController _controller;
  Animation<Offset> _slideAnimation;
  double _offset = 0.0;
 
  @override
  void initState() {
    super.initState();
    _controller = AnimationController(vsync: this, duration: Duration(milliseconds: 300));
    _slideAnimation = Tween<Offset>(begin: Offset(0, 0), end: Offset(0.2, 0.2)).animate(_controller);
  }
 
  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
 
  void _slideCard(double offset) {
    setState(() {
      _offset += offset;
      _controller.forward(from: 0.0);
    });
  }
 
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Positioned(
          left: _offset * 2,
          top: _offset * 2,
          child: SlideTransition(
            position: _slideAnimation,
            child: Container(
              margin: EdgeInsets.all(20),
              decoration: BoxDecoration(
                color: Colors.blue,
                borderRadius: BorderRadius.circular(10),
              ),
              child: Text('Draggable Card'),
            ),
          ),
        ),
        GestureDetector(
          onVerticalDragStart: (DragStartDetails details) {
            _slideAnimation = Tween<Offset>(
              begin: _slideAnimation.value,
              end: Offset(0.0, details.globalPosition.dy - details.localPosition.dy),
            ).animate(_controller);
          },
          onVerticalDragUpdate: (DragUpdateDetails details) {
            _slideAnimation = Tween<Offset>(