vue3解决放大镜问题

<template>
  <div class="goods-image">
    <!-- 大图 -->
    <div
      v-show="show"
      class="large"
      :style="[{backgroundImage:`url(${images[currIndex]})`},largePosition]"
    ></div>
    <!-- 中图 -->
    <div
      class="middle"
      ref="target"
    >
      <img
        :src="images[currIndex]"
        alt=""
      >
      <!-- 遮罩色块 -->
      <div
        v-show="show"
        class="layer"
        :style="layerPosition"
      ></div>
    </div>
    <!-- 小图 -->
    <ul class="small">
      <li
        v-for="(img,i) in images"
        :key="i"
        :class="{active:i===currIndex}"
      >
        <img
          @mouseenter="currIndex=i"
          :src="img"
          alt=""
        >
      </li>
    </ul>
  </div>
</template>

<script>
import { reactive, ref, watch } from 'vue'
// 这个需要下载 npm i @vueuse/core / yarn add @vueuse/core
import { useMouseInElement } from '@vueuse/core'
export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup (props) {
    // 当前预览图的索引
    const currIndex = ref(0)

    // 1. 是否显示遮罩和大图
    const show = ref(false)
    // 2. 遮罩的坐标(样式)
    const layerPosition = reactive({
      left: 0,
      top: 0
    })
    // 3. 大图背景定位(样式)
    const largePosition = reactive({
      backgroundPositionX: 0,
      backgroundPositionY: 0
    })
    // 4. 使用useMouseInElement得到基于元素左上角的坐标和是否离开元素数据
    const target = ref(null)
    const { elementX, elementY, isOutside } = useMouseInElement(target)
    watch([elementX, elementY, isOutside], () => {
      // 5. 根据得到数据设置样式数据和是否显示数据
      show.value = !isOutside.value
      // 计算坐标
      const position = { x: 0, y: 0 }

      if (elementX.value < 100) position.x = 0
      else if (elementX.value > 300) position.x = 200
      else position.x = elementX.value - 100

      if (elementY.value < 100) position.y = 0
      else if (elementY.value > 300) position.y = 200
      else position.y = elementY.value - 100
      // 给样式赋值
      // 中图遮罩层的位置
      layerPosition.left = position.x + 'px'
      layerPosition.top = position.y + 'px'
      // 大图的显示的位置
      largePosition.backgroundPositionX = -2 * position.x + 'px'
      largePosition.backgroundPositionY = -2 * position.y + 'px'
    })

    return { currIndex, show, layerPosition, largePosition, target }
  }
}
</script>
<style scoped lang="less">
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  z-index: 500;
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
  .middle {
    width: 400px;
    height: 400px;
    background: #f5f5f5;
    position: relative;
    cursor: move;
    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      left: 0;
      top: 0;
      position: absolute;
    }
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer;
      &:hover,
      &.active {
        border: 2px solid skyblue;
      }
    }
  }
}
</style>