vue.js 3.2.22：用@vueuse/core实现图片懒加载(@vueuse/core@7.0.3)

一，安装所需的库@vueuse/core

liuhongdi@lhdpc:/data/vue/lazy$ npm install --save @vueuse/core

说明：刘宏缔的架构森林是一个专注架构的博客，地址：https://www.cnblogs.com/architectforest

         对应的源码可以访问这里获取： https://github.com/liuhongdi/
         或: https://gitee.com/liuhongdi

说明：作者:刘宏缔 邮箱: 371125307@qq.com

二，编写代码

1,directive/LazyImage.js

import { useIntersectionObserver } from '@vueuse/core'
export default {
    install (app) {
        app.directive('lazySrc', {
            mounted (el, binding) {
                let imgDefault="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7";
                el.src = imgDefault // 指定默认显示内容
                const { stop } = useIntersectionObserver(el, ([{ isIntersecting }]) => {
                    if (isIntersecting) { // 如果在可见区域中
                        el.onerror = () => { //如图片加载失败
                            el.src = imgDefault
                        }
                        stop() //如已在可见区域内则下次不再监听
                        //set url
                        el.src = binding.value
                        console.log(el.src+'加载成功');
                        //set style
                        el.className = 'imgFade';
                    }
                }, { threshold: 0 }) // 当可视区域宽高为0就触发
                //console.log(el, binding.value)
            }
        })
    }
}

2,main.js

import { createApp } from 'vue'
import App from './App.vue'
import LazyImage from '@/directive/LazyImage'
createApp(App).use(LazyImage).mount('#app')

3,Lazy.vue

<template>
<div style="100%;height:100vh;display: flex;flex-direction: column;">
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com//ware/ueditor/image/20211105/1636086111740260.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/slider/1757.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/sowhatimg/ware/orig/2/37/37757.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/sowhatimg/ware/orig/2/34/34656.png'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/slider/1759.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/sowhatimg/ware/orig/2/37/37753.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com//ware/ueditor/image/20211112/1636699398743493.jpg'" />
  <img style="100%;" v-lazySrc="'https://imgs-qn.iliangcang.com/ware/slider/1753.jpg'" />
</div>
</template>

<script>
export default {
  name: "Lazy",
  setup() {
  }
}
</script>

<style scoped>
.imgFade {
  transition: 1.5s opacity;
  /*-webkit-animation: fadeIn 0.4s linear;*/
  animation: fadeIn  1.5s linear;
}
@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}
</style>

三，测试效果

 

四，查看vue的版本:

liuhongdi@lhdpc:/data/vue/lazy$ npm list vue
lazy@0.1.0 /data/vue/lazy
├─┬ @vue/cli-plugin-babel@4.5.15
│ └─┬ @vue/babel-preset-app@4.5.15
│   └── vue@3.2.22 deduped
├─┬ @vueuse/core@7.0.3
│ ├─┬ @vueuse/shared@7.0.3
│ │ └── vue@3.2.22 deduped
│ ├─┬ vue-demi@0.12.1
│ │ └── vue@3.2.22 deduped
│ └── vue@3.2.22 deduped
└─┬ vue@3.2.22
  └─┬ @vue/server-renderer@3.2.22
    └── vue@3.2.22 deduped