Flutter拖拽小部件

编写初衷

因为项目需要浮动按钮所以我这里开发了一个拖动小部件

这里直接上代码

import 'dart:math';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

// ignore: must_be_immutable
class TouchMove extends StatefulWidget {
  TouchMove({Key key,this.child}) : super(key: key);
  Widget child;
  @override
  _TouchMoveState createState() => _TouchMoveState();
}

class _TouchMoveState extends State<TouchMove> {
  //静止状态下的offset
  Offset idleOffset=Offset(ScreenUtil().setWidth(600), ScreenUtil().setHeight(1100));
  // //本次移动的offset
  // Offset moveOffset=Offset(0, 0);
    //本次移动的offset
  Offset moveOffset=Offset(ScreenUtil().setWidth(600), ScreenUtil().setHeight(1100));
  //最后一次down事件的offset
  Offset lastStartOffset=Offset(ScreenUtil().setWidth(600), ScreenUtil().setHeight(1100));

  @override
  void initState() {
    super.initState();
  }
  @override
  Widget build(BuildContext context) {
    return GestureDetector(
        behavior: HitTestBehavior.deferToChild,
        onPanStart: (detail) {
              setState(() {
                  lastStartOffset=detail.globalPosition;
              });
        },
        onPanUpdate: (detail){
              setState(() {
                moveOffset=detail.globalPosition-lastStartOffset+idleOffset;
                moveOffset=Offset(moveOffset.dx,  moveOffset.dy);
              });
            },

            onPanEnd: (detail) {
              setState(() {
                idleOffset=moveOffset*1;
              });
            },
       child:Transform.translate(
        offset: moveOffset,
        child: Container(
         
          child:widget.child,
        
        ))
      //  widget.child,
    );
  }
}