微信小程序：实现可拖动悬浮图标（列表页添加按钮）

实现的效果截图

主要代码

.wxml

图标

.wxss

    /**可拖动悬浮按钮样式表**/
.btn_Suspension{
    position: fixed;
    height: 90rpx;
    width: 90rpx;
    background-color: rgba(255, 255, 255, 0.755);
    border-radius: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 99999;
    box-shadow: 1px 0px 1px 1px #ede7e7;
  }
  .Suspension_logo{
    position:absolute;
    height:100%;
    width:100%;
  }

.js

var startPoint
Page({
  data: {
    //按钮位置参数
    buttonTop: 0,
    buttonLeft: 0,
    windowHeight: '',
    windowWidth: ''
  },
  onLoad:function(){
  
    var that =this;
    wx.getSystemInfo({
      success: function (res) {
        console.log(res);
        // 屏幕宽度、高度
        console.log('height=' + res.windowHeight);
        console.log('width=' + res.windowWidth);
        // 高度,宽度 单位为px
        that.setData({
          windowHeight:  res.windowHeight,
          windowWidth:  res.windowWidth,
          buttonTop:res.windowHeight*0.70,//这里定义按钮的初始位置
          buttonLeft:res.windowWidth*0.70,//这里定义按钮的初始位置
        })
      }
    })
  },
 
  },
  //以下是按钮拖动事件
  buttonStart: function (e) {
    startPoint = e.touches[0]//获取拖动开始点
  },
  buttonMove: function (e) {
    var endPoint = e.touches[e.touches.length - 1]//获取拖动结束点
    //计算在X轴上拖动的距离和在Y轴上拖动的距离
    var translateX = endPoint.clientX - startPoint.clientX
    var translateY = endPoint.clientY - startPoint.clientY
    startPoint = endPoint//重置开始位置
    var buttonTop = this.data.buttonTop + translateY
    var buttonLeft = this.data.buttonLeft + translateX
    //判断是移动否超出屏幕
    if (buttonLeft+50 >= this.data.windowWidth){
      buttonLeft = this.data.windowWidth-50;
    }
    if (buttonLeft<=0){
      buttonLeft=0;
    }
    if (buttonTop<=0){
      buttonTop=0
    }
    if (buttonTop + 50 >= this.data.windowHeight){
      buttonTop = this.data.windowHeight-50;
    }
    this.setData({
      buttonTop: buttonTop,
      buttonLeft: buttonLeft
    })
  },
  buttonEnd: function (e) {
  }
})