创建个vue2项目,直接把代码放到一个vue2页面内运行就好,下面代码拿来即用

<template>
  <div>
    <div class="replace_menu_mask" @click="closeMenu">
      <img :src="replaceImg" alt="" style="width: 100%;">
    </div>
    <div :class="{ 'replace_menu': flag }" v-if="flag">
      <div class="replace_menu_item" @click="randomBgImg">系统随机</div>
      <div class="replace_menu_item">
        相册<input type="file" @change="perPhotoAlbum" name="file" id="file" />
      </div>
      <div class="replace_menu_item item_cancel" @click="closeMenu">取消</div>
    </div>
  </div>
</template>

<script>
export default {
  name: 'replaceMenu',
  data () {
    return {
      flag: true, // 控制弹窗显示
      replaceImg: '', // 选取的图片地址
    }
  },
  methods: {
    closeMenu () {
      // 关闭弹窗
      this.flag = false
    },
    // 本地图片读取(移动端则选择手机相册,pc端选择文件夹)
    perPhotoAlbum (e) {
      const that = this
      let file = e.target.files[0]
      that.getBase64(file).then(res => {
        that.replaceImg = res // 图片地址源
        // 选择完毕后关闭弹窗
        this.flag = false
      })
    },
    // 二进制流转换为base64 格式。
    getBase64 (data) {
      return new Promise((resolve, reject) => {
        const blob = new Blob([data], {
          type: "image/jpg"
        }) //类型一定要写！！！
        const reader = new FileReader()
        reader.readAsDataURL(blob)
        reader.onload = () => resolve(reader.result)
        reader.onerror = (error) => reject(error)
      })
    },
    // 随机显示图片
    randomBgImg () {
      // 随机图片这个自己写个随机数就好,然后抽取不同图片把路径放上去即可,这里讲的主要是从本地拿图片并转化base64格式用于显示
    }
  }
}
</script>

<style lang="less">
.replace_menu_mask {
  width: 100%;
  height: 100%;
  position: fixed;
  top: 0;
  left: 0;
  background-color: rgba(0, 0, 0, .5);
  z-index: 99;
}

.replace_menu {
  width: 100%;
  position: fixed;
  bottom: 0;
  left: 0;
  z-index: 9999;
  transform: translateY(1000px);
  background-color: #f2f2f2;
  border-top-left-radius: 0.41rem;
  border-top-right-radius: 0.41rem;
  animation: mobileBox 0.5s forwards ease-in-out;

  .replace_menu_item:first-child {
    border-top-left-radius: 0.41rem;
    border-top-right-radius: 0.41rem;
  }

  .replace_menu_item {
    text-align: center;
    padding: 0.307rem;
    border-bottom: 0.0205rem solid rgba(0, 0, 0, .1);
    line-height: 0.41rem;
    background-color: #fff;
    color: #333;
    position: relative;

    #file {
      height: 0.205rem;
    }

    input[type="file"] {
      position: absolute;
      top: 0.41rem;
      right: 0;
      background-color: #fff;
      transform: translate(-300px, 0px) scale(4);

      opacity: 0;
      filter: alpha(opacity=0);
    }
  }

  .item_cancel {
    margin-top: 0.205rem;
    padding: 0.41rem;
  }
}

@keyframes mobileBox {
  0% {
    transform: translateY(1000px);
  }

  100% {
    transform: translateY(0px);
  }
}
</style>

效果图

选择完图片后直接展示了