放大镜效果(vue)

使用步骤

1.引入相应的包

因为使用了less所以这一步不是必须的

npm i less --save
npm i less-loader --save

2.样式

代码如下（示例）：

<template>
    <div class="spec-preview">
      <img :src="myImg.imgUrl" />
      <div class="event" @mousemove="handler"></div>
      <div class="imgTela">
        <img :src="myImg.imgUrl" ref="imgTela" />
      </div>
      <div class="layer" ref="layer"></div>
    </div>
</template>

<script>
export default {
  name: 'App',
  data() {
    return {
      img: []
    }
  },
  methods: {
    handler(e) {
      // 获取元素
      let layer = this.$refs.layer
      let imgTela = this.$refs.imgTela
      // 获取小方块到大方块的距离
      let left = e.offsetX - layer.offsetWidth / 2
      let top = e.offsetY - layer.offsetHeight / 2
      // 添加约束
      if (left <= 0) left = 0
      if (left >= layer.offsetWidth) left = layer.offsetWidth
      if (top <= 0) top = 0
      if (top >= layer.offsetHeight) top = layer.offsetHeight
      // 设置偏移量
      layer.style.left = left + 'px'
      layer.style.top = top + 'px'
      imgTela.style.left = -2 * left + 'px'
      imgTela.style.top = -2 * top + 'px'
    }
  },
  computed: {
    myImg() {
      return this.img[0] || {}
    }
  }
}
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 600px;
  height: 342px;
  margin: 20px auto;

  img {
    width: 100%;
    height: 100%;
  }

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

  .layer {
    width: 50%;
    height: 50%;
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

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

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

  .event:hover ~ .layer,
  .event:hover ~ .imgTela {
    display: block;
  }
}
</style>

该处使用的url网络请求的数据，所以img默认是个空数组

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