import 'package:flutter/material.dart';

/// create by 张风捷特烈 on 2020-03-22
/// contact me by email 1981462002@qq.com
/// 说明: 
//    {
//      "widgetId": 105,
//      "name": 'LongPressDraggable与DragTarget联用',
//      "priority": 1,
//      "subtitle":
//          "【child】 : 孩子   【Widget】\n"
//          "【feedback】 : 拖拽时的孩子   【Widget】\n"
//          "【axis】 : 拖动的轴   【Axis】\n"
//          "【data】 : 数据   【T】\n"
//          "【onDragStarted】 : 开始拖拽   【Function()】\n"
//          "【onDragEnd】 : 结束拖拽   【Function(DraggableDetails)】\n"
//          "【onDragCompleted】 : 拖拽完成   【Function()】\n"
//          "【onDraggableCanceled】 : 拖拽取消   【Function(Velocity,Offset)】",
//    }
class CustomLongPressDraggable extends StatefulWidget {
  @override
  _CustomLongPressDraggableState createState() => _CustomLongPressDraggableState();
}

class _CustomLongPressDraggableState extends State<CustomLongPressDraggable> {
  Color _color = Colors.grey;
  String _info = 'DragTarget';

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: <Widget>[
          Wrap(
            children: _buildColors(),
            spacing: 10,
          ),
          SizedBox(height: 20,),
          _buildDragTarget()
        ],
      ),
    );
  }

  List<Widget> _buildColors() {
    var colors = [
      Colors.red,
      Colors.yellow,
      Colors.blue,
      Colors.green,
      Colors.orange,
      Colors.purple,
      Colors.cyanAccent
    ];
    return colors
        .map(
          (e) => LongPressDraggable<Color>(
              onDragStarted: () => setState(() => _info = '开始拖拽'),
              onDragEnd: (d) => setState(() => _info = '结束拖拽'),
              onDragCompleted: () => _info = '拖拽完成',
              onDraggableCanceled: (v, o) => _info = '拖拽取消',
          child: Container(
            width: 30,
            height: 30,
            alignment: Alignment.center,
            child: Text(
              colors.indexOf(e).toString(),
              style: TextStyle(
                  color: Colors.white, fontWeight: FontWeight.bold),
            ),
            decoration: BoxDecoration(color: e, shape: BoxShape.circle),
          ),
          data: e,
          feedback: Container(
            width: 25,
            height: 25,
            decoration: BoxDecoration(color: e, shape: BoxShape.circle),
          )),
    )
        .toList();
  }

  Widget _buildDragTarget() {
    return DragTarget<Color>(
        onAccept: (data) => setState(() {
          _info='onAccept';
          _color = data;
        }),
        builder: (context, candidateData, rejectedData) => Container(
            width: 150.0,
            height: 50.0,
            color: _color,
            child: Center(
              child: Text(
                _info,
                style: TextStyle(color: Colors.white),
              ),
            )));
  }
}