Flutter自定义可拖动组件

以下是一个简化的Flutter自定义可拖动组件的示例代码：

import 'package:flutter/material.dart';
 
class DraggableCard extends StatefulWidget {
  final String cardTitle;
 
  const DraggableCard({Key? key, required this.cardTitle}) : super(key: key);
 
  @override
  _DraggableCardState createState() => _DraggableCardState();
}
 
class _DraggableCardState extends State<DraggableCard> with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<Offset> _offsetAnimation;
 
  @override
  void initState() {
    super.initState();
    _controller = AnimationController(vsync: this, duration: const Duration(seconds: 1));
    _offsetAnimation = Tween<Offset>(begin: Offset(0, 0), end: Offset(0.5, 0.5)).animate(_controller);
  }
 
  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
 
  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      builder: (context, child) {
        return Positioned(
          left: 100,
          top: 100,
          child: Draggable(
            data: widget.cardTitle,
            child: Card(
              child: ListTile(
                title: Text(widget.cardTitle),
              ),
            ),
            feedback: Card(
              child: ListTile(
                title: Text(widget.cardTitle),
              ),
            ),
            childWhenDragging: Opacity(
              opacity: 0.5,
              child: Card(
                child: ListTile(
                  title: Text(widget.cardTitle),
                ),
              ),
            ),
          ),
        );
      },
    );
  }
}

这个示例定义了一个可拖动的卡片组件，它使用Draggable来实现拖拽功能，并且通过AnimatedBuilder来实现拖动过程中的动画效果。这个组件可以被用在需要实现卡片拖动交互的Flutter应用中。