vue pc放大镜效果

html 

<div class="choose" ref="choose">
            <div
              class="content"
              ref="content"
              @mousemove="handleMove"
              @mouseout="handleOut"
            >
              <img
                :src="'http://shanneng.oss-cn-hangzhou.aliyuncs.com' + imagespic"
              />
              <div class="shadow" ref="shadow"></div>
            </div>
</div>
<div class="larger" ref="larger">
            <img
              :src="'http://shanneng.oss-cn-hangzhou.aliyuncs.com' + imagespic"
              ref="big"
            />
</div>

js

 // 获取元素到文档区域的坐标
    getPosition: function (element) {
      var dc = document,
        rec = element.getBoundingClientRect(),
        x = rec.left, // 获取元素相对浏览器视窗window的左、上坐标
        y = rec.top;
      // 与html或body元素的滚动距离相加就是元素相对于文档区域document的坐标位置
      x += dc.documentElement.scrollLeft || dc.body.scrollLeft;
      y += dc.documentElement.scrollTop || dc.body.scrollTop;
      return {
        left: x,
        top: y,
      };
    },
    handleMove(evt) {
      var larger = this.$refs.larger;
      var shadow = this.$refs.shadow;
      var big = this.$refs.big;
      var pos = this.getPosition(this.$refs.choose);
      var shadowRect = shadow.getBoundingClientRect();
      var bigRect = big.getBoundingClientRect();
      var contentRect = this.$refs.content.getBoundingClientRect();
      var maxX = contentRect.width - shadowRect.width;
      var maxY = contentRect.height - shadowRect.height;

      var X = evt.pageX - pos.left - shadowRect.width / 2;
      var Y = evt.pageY - pos.top - shadowRect.height / 2;

      if (X <= 0) {
        X = 0;
      }
      if (X >= maxX) {
        X = maxX;
      }
      if (Y <= 0) {
        Y = 0;
      }
      if (Y >= maxY) {
        Y = maxY;
      }
      // 防止遮罩层粘滞，跟随鼠标一起滑出大图位置
      var bigX = (X * bigRect.width) / contentRect.width;
      var bigY = (Y * bigRect.height) / contentRect.height;
      //  bigX / bigW = X / contentW,主图和遮罩层之间存在两倍关系，放大图和原图之间也有两倍关系
      shadow.style.left = X + "px";
      shadow.style.top = Y + "px";

      // console.log(X, Y, bigX, bigY);

      big.style.left = -bigX + "px";
      big.style.top = -bigY + "px";

      larger.style.display = "block";
      shadow.style.display = "block";
    },
    handleOut(evt) {
      var larger = this.$refs.larger;
      var shadow = this.$refs.shadow;
      larger.style.display = "none";
      shadow.style.top = "-1000px";
      console.log(evt);
    },

css

.choose {
  width: 441px;
  height: 441px;
  margin: 22px;
  /* background-color: #3fac49; */
  /* position: relative; */
}
.larger {
  width: 440px;
  height: 440px;
  position: absolute;
  top: 25px;
  left: 500px;
  float: left;
  overflow: hidden;
  display: none;
}

.larger img {
  width: 800px;
  height: 800px;
  position: absolute;
  left: 0;
  top: 0;
}

.shadow {
  width: 200px;
  height: 200px;
  background-color: rgba(145, 200, 200, 0.4);
  position: absolute;
  left: 0;
  top: 0;
  z-index: 10;
  display: none;
}