vue - 图片的放大镜功能

// html
<div class="productLeft">
   <!-- 左侧中图  -->
   <div class="mdImg">
      <img :src="qall" alt="">
   </div>
   <!-- 遮罩层  -->
   <div v-show="isShow" class="marks" :style="{top:top+'px',left:left+'px'}"></div>
      <!-- 遮罩层 玻璃板 superMarks -->
      <div v-if="isPC==false" @touchstart.prevent="enter" @touchend.prevent="leave"  @touchmove.prevent="marks" @click.prevent="sub()" class="superMarks" ></div>
      <div v-if="isPC==true" @mouseenter="enter" @mouseleave="leave"  @mousemove="marks" @click.prevent="sub()" class="superMarks" ></div>
      <div v-show="isShow" class="lgImg">
          <img :src="qallBig" alt="" :style="{top:topLgImg+'px',left:leftLgImg+'px'}">
      </div>
</div>

// js
export default{
   name : 'blog-header',
   data(){
     return{
       isPC:true,
       // 大图片
       qall: '../../static/image/土味.jpg',
       qallBig: '../../static/image/土味Big.jpg',
       isShow:false,   //控制遮罩层marks和大图片是否显示"
       left:0,       //marks左移位置
       top:0,         //marks下移位置
       leftLgImg:0,       //大图lgImg移动的位置
       topLgImg:0         //大图lgImg移动的位置
     }
    },
    methods:{
       //鼠标进入和离开
       enter(){
         this.isShow=true;
       },
       leave(){
         this.isShow=false;
       },
       //遮罩层放大镜
       marks(e){
         var marksWidth=48;//marks的宽
         var marksHeight=48;//marks的高
         if(this.isPC==true){
           //PC端
           this.left=e.offsetX-marksWidth/2;   
           this.top=e.offsetY-marksHeight/2;
           if(this.left<0){
              this.left=0;
           }else if(this.left>160){
              this.left=160;
           }
           if(this.top<0){
              this.top=0;
           }else if(this.top>160){
              this.top=160;
           }
           //大d图片除以小的图片的宽高
           this.leftLgImg=-this.left*320/160;
           this.topLgImg=-this.top*181/91;
         }else{
           //移动端
           this.left=e.changedTouches[0].clientX-marksWidth/2;   
           this.top=e.changedTouches[0].clientY-marksHeight/2;
           if(this.left<0){
              this.left=0;
           }else if(this.left>160){
              this.left=160;
           }
           if(this.top<0){
              this.top=0;
           }else if(this.top>45){ //45就是小图片的高度的一半，91/2
              this.top=45;
           }
           //大d图片除以小的图片的宽高
           this.leftLgImg=-this.left*320/160;
           this.topLgImg=-this.top*181/91;
         }
      }

   },
   mounted(){
      if (navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i,)) {
          this.isPC = false; 
      } else {
          console.log('PC端')
      }
    }
}

  /* 左侧大小图样式 160*91  320*181*/
    .productLeft{
        width:160px;
        position: relative;
    }
    /* 左侧中图 */
    .mdImg,.mdImg>img{
        width:160px;
        height:91px;
        margin-left: 15px;
    }
    /*遮罩层superMarks */
    .superMarks{
        width:160px;
        height:91px;
        background-color:rgba(220, 220, 220, 0);
        position:absolute;
        top:0px;
        left:0px;
    }
    /* 遮罩层 */
    .marks{
        width:48px;
        height:48px;
        position:absolute;
        background-color:rgba(220, 220, 220, 0.5);
        /*top:0px;  //内联设置了动态的top，left
        left:0px;*/
    }
    
    /* 左侧隐藏大图 */
    .lgImg{
        width:160px;
        height:91px;
        overflow: hidden;
        position:absolute;
        top:0px;
        left:195px;
        border:2px solid #aaa;
        background-color:#fff;
    }
    .lgImg img{
        width:320px;
        height:181px;
        position:absolute;
        /*top:100px;
        left:100px;*/
    }