vue3.0 黑暗风格（Vue3.0 手写放大镜效果）

<template>
  <li ref="target">
    <h1>Hello world</h1>
  </li>
</template>
 
<script>
import { ref } from 'vue'
import { useMouseInElement } from '@vueuse/core'
 
export default {
  setup() {
    const target = ref(null)
 
    const { x, y, isOutside } = useMouseInElement(target)
 
    return { x, y, isOutside }
  }
}
</script>

 <li class="layer" :style="layerStyle"></li> //这是遮罩层
setup(){   //下面是实现鼠标跟随的代码
const layerStyle = reactive({
      top: '0px',
      left: '0px'
    })
    // 监听三个值的变化,watch第一个参数用数组
    watch([elementX, elementY, isOutside], () => {
      // layerStyle.left = elementX.value / 2 + 'px'
      // layerStyle.top = elementY.value / 2 + 'px'
      let top = elementY.value - 100
      let left = elementX.value - 100
 
      // 给遮罩元素赋值位置
      if (top < 0) top = 0
      if (top > 200) top = 200
      if (left < 0) left = 0
      if (left > 200) left = 200
      layerStyle.top = top + 'px'
      layerStyle.left = left + 'px'
    })
    return { elementX, elementY, isOutside, target, layerStyle }
 
}

 <li class="large" :style="{ backgroundImage:`url(${images[current]})`,...largeStyle }"></li>

 .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;
 }