页面布局的结构如下:

 <div class="spec-preview">
    <img :src="xxx" />
    <div class="event" @mousemove="handler"></div>
    <!-- 显示放大的图片 -->
    <div class="big">
      <img :src="xxx" ref="big"/>
    </div>
    <!-- 遮罩层 -->
    <div class="mask" ref="mask"></div>
  </div>

css样式如下(也可以自己修改样式):


.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  .spec-preview img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    .big img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover~.mask,
  .event:hover~.big {
    display: block;
  }
}

methods(即为实现代码功能片段)如下:

  methods: {
      handler(event) {
        let mask = this.$refs.mask;
        let big = this.$refs.big;
        //计算遮罩的左值以及顶部的值
        let left = event.offsetX - mask.offsetWidth / 2
        let top = event.offsetY - mask.offsetHeight / 2
        //判断方位超出的情况
        if (left < 0) {
          left = 0
        } else if (left > mask.offsetWidth) {
          left = 200
        }
        if (top < 0) {
          top = 0
        } else if (top > mask.offsetHeight) {
          top = 200
        }
        //将遮罩以及big图赋值定位  (此外big图为普通图的两倍大小 且方位为负值)
        mask.style.left = left + 'px'
        mask.style.top = top + 'px'
        big.style.left = -2 * left + 'px'
        big.style.top = -2 * top + 'px'
      }
    }

难点在于big图的img是普通图的2倍且展示的方位与普通图方位相反所以 *-2

最后实现如下如果:

 

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