vue element 框架 自定义轮播图，点击上下翻图，并让图片居中

1、素材展示窗口，左侧预览滚动区域按分辨率做一屏最大预览数量做均分（超过最大预览数量是滚动条滑动）
 2、左侧预览滚动区域增加浅灰色底色要求与滚动条颜色区分
 3、预览滚动区域单个区域高度固定，素材图按比例缩放
 4、素材图展示大图上下顶部及底部区域增加上下翻页箭头，点击有按压效果
 5、预览的素材大图为左侧预览区域居中的素材，上下翻页，滚动区域居中素材跟随翻滚
  以上是需求，下面贴代码

轮播图效果

 css

.material-row {
  display: inline-block;
   55px;
  max-height: 60px;
//   float: left;
  margin-left: 3px;
  cursor: pointer;
//   vertical-align: center;
}


.material-scroll{ //滚动div
  display:flex;
  height:70vh;
  justify-content: center;
  align-items: center;float: left;
   25%;
  overflow-y: auto;
  // background: #ddd;
}

.material-left{
    80%;
   max-height: 70vh;
  //  overflow-y: auto;
  //  display:flex;
  //  justify-content: center;
  //  align-items: center;
   
  //  float: left;
  //  max-height: 300px;
  .material-box{
    margin-bottom: 5px;
    
    >div{
      cursor: pointer;
      display: flex;
      justify-content: center;
      align-items: center;  
      height: 70px;
      95%;
      border: 1px solid #ddd;
      background: #fff;
      overflow: hidden;
    }
  }
  .material-box:hover{
    border: 2px solid blue;
  }
  .blue{
    border: 2px solid blue;
  }
}
.material-right{
  height:70vh;
  text-align:center;
  margin-left: 26%;
  position: relative;
  margin-right:10px;
  // display: flex;
  // justify-content: center;
  // align-items: center;  

  >div{
    height: 66vh;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  
    .arrow-left {
      position: absolute;
      top: -0%;
      left: 2%;
      cursor: pointer;
      // background: #dcdfe6;
      95%;
      height: 6vh;
      font-size: 50px;
      font-weight: bold;
    }
    .arrow-right {
      position: absolute;
      bottom: 5%;
      left: 2%;
      cursor: pointer;
      // background: #dcdfe6;
      95%;
      height: 6vh;
      font-size: 50px;
      font-weight: bold;
    }
    .arrow-left:hover{
      background: #dcdfe6;
      opacity: 0.5;
      color: #fff;
    }
    .arrow-right:hover{
      background: #dcdfe6;
      opacity: 0.5;
      color: #fff;
    }
}

　　

js

// 素材弹框

openMaterial(list, item, index) {

// console.log(list)

this.materialList = list;

this.showMaterial = true;

this.materialKey = index;

setTimeout(()=> { //初始化滚动高度，带定时器获取元素

let box = this.$refs['material-scroll']

box.scrollTop = 0

}, 50 )

},

materialKeyEdit(num) {
      // console.log(this.materialKey)
     
      this.materialKey = num
    },
    materialKeyAdd(num){ //上下键函数
      let box = this.$refs['material-scroll']
      // console.log(this.$refs['material-scroll'])
      console.log(window.getComputedStyle(box).height)
      let px = window.getComputedStyle(box).height  //可视范围的高度
      let height = Number(px.substring(0,px.length-2)) //截取字符串，移除px
      console.log(height)
      let number = Math.round(height/150) //一个图片75px,获取高度一半需要多少图片，让其居中
      console.log(number)
      // box.scrollTop = 500
      if(this.materialList.length>1){
        if (
          (this.materialKey == 0 && num > 0) ||
          (this.materialKey == this.materialList.length - 1 && this.materialList.length - 1>0 && num < 0) ||
          (this.materialKey > 0 &&
            this.materialKey < this.materialList.length - 1)
        ) {
          this.materialKey += num;
          if(this.materialKey<number || this.materialKey+(number +1) > this.materialList.length){  //开始或结尾不滚动
            if(this.materialKey<number){
              box.scrollTop = 0
            }
            if(this.materialKey+(number +1) > this.materialList.length){
              box.scrollTop = (this.materialList.length)*75
            }
            
          } else {
              box.scrollTop += 75*num  //一次滚动一个图片的高度
          }
        }
      }
    },

 
template

<el-dialog class="material-dialog"

title=""

:visible.sync="showMaterial"

width="50%" max-height="50%" top="10vh" center :close-on-click-modal=false>

<!-- <div v-if="this.materialList.length>1" class="arrow-left" @click="materialKeyEdit(-1)"><img src="../../assets/image/arrow-left.png" alt=""></div> -->

<div class="material-scroll" ref="material-scroll">

<div class="material-left" id="material-scroll">

<div class="material-box" v-for="(item,index) in materialList" :key="index" @click="materialKeyEdit(index)" :class="{'blue':index==materialKey}">

<div v-if="item.match(/((http|https)://)/ig) && item.match(/((.jpg|.png|.gif))/ig)"><img style="max-100%;max-height:100%" class="" :src="item" alt=""> </div>

<div v-else-if="item.match(/((http|https)://)/ig) && item.match(/((.mp4|.rmvb|.rm|.3gp|.mov|.avi))/ig)"><video style="max-100%;max-height:100%" :src="item" alt=""></video> </div>

<div style="80%" v-else>{{item}}</div>

</div>

</div>

</div>

<div class="material-right" style="" v-for="(item,index) in materialList" :key="index" v-show="index==materialKey">

<div class="arrow-left" @click="materialKeyAdd(-1)"><i class="el-icon-arrow-up"></i></div>

<div v-if="item.match(/((http|https)://)/ig) && item.match(/((.jpg|.png|.gif))/ig)"><img class="" :src="item" alt="" style="max-height:45vh"> </div>

<div v-else-if="item.match(/((http|https)://)/ig) && item.match(/((.mp4|.rmvb|.rm|.3gp|.mov|.avi))/ig)"><video style="max-height:45vh" :src="item" alt="" controls="controls"></video> </div>

<div v-else>{{item}}</div>

<div class="arrow-right" @click="materialKeyAdd(1)"><i class="el-icon-arrow-down"></i></div>

<p style="text-align:center">{{index+1}} / {{materialList.length}}</p>

</div>

<!-- <div v-if="this.materialList.length>1" class="arrow-right" @click="materialKeyEdit(1)"><img src="../../assets/image/arrow-right.png" alt=""></div> -->

</el-dialog>