<template>
  <van-image-preview v-model="isShowImg" :images="image" @change="imgChange">
    <div slot="cover" class="color-high">
      <van-icon name="down" class="down-img" @click="downLoadHandle"/>
    </div>
  </van-image-preview>
</template>
//想要让下载图标显示，要改变van-image-preview__cover的属性（自己写，还要修改vant的官网css样式，不然图标没有显示）
.van-image-preview__cover{
  bottom:20% !important;
  left:44% !important;
}

<script>
import {ImagePreview} from 'vant';//从vant导入图片预览组件
export default{
	//传入的参数
	props:{
		isShow:Boolean,//控制是否显示组件
		image:{type:Array,default(){return []}},//要显示的数组，简单数组格式，
	},
	computed:{
		//必须重新在组件中定义一个控制组件显示的值，不然会报错
		isShowImg:{
			set(val){this.$emit('close'),val},//用于父组件接受，改变isShow的值
			get(){return this.isShow}
		}
	},
	data(){
		return{
			index:0,//图片的下标
		}
     },
     methods:{
     	downloadHandle(){
			let image = new Image();
			image.setAttribute('crossOrigin','anonymous');
			let _this=this;
			image.onload = function(){
				let canvas = document.createElement('canvas');
				canvas.width = image.width;
				canvas.height = image.height;
				let context = canvas.getContext("2d");
				context.drawImage(image,0,0,image.width,image.height);
				let url = canvas.toDataURL(_this.image(_this.index));
				let a =document.createElement('a');
				let event = new MouseEvent('click');
				a.download = Math.random()*1000+'.jpg'||'photo';
				a.href=url;
				a.dispatchEvent(event)	
			}
			image.src=_this.image(_this.index);
		},
		imgChange(index){this.index=index;}
     }
}

</script>

5)父组件调用

<template>
	<image-preview :isShow="isShow" :image="filex" @close="closeImg"></image-preview>
	//此处的filex必须是简单的数组['1','2']
</template>

<script>
import ImagePreview from '组件路径'
</script>