解决v-lazy-image在qq浏览器x5内核下无效

原创
2019/04/20 15:20
阅读数 260

故障:在安卓qq浏览器中,v-lazy-image始终无法显示。

原因分析:

经调试,发现qq浏览器中IntersectionObserver缺少一个isIntersecting字段,而v-lazy-image插件是根据isIntersecting来显示图片的,故只能借助intersectionRatio判断。

另外还有一点差别就是如果v-lazy-image组件初始宽高为0的话,会导致intersectionRatio始终为0。

解决方案:

基于v-lazy-image源码修改自定义一个vue插件模块,代码见文末。

v-lazy-image使用的时候设置 src-placeholder ,保证v-lazy-image有个初始大小,这里我随便制作了一个 1x1 的空白图片,示例代码如下

main.js 修改

import { VLazyImagePlugin } from './plugins/VLazyImage'
// polyfill
require('intersection-observer')
Vue.use(VLazyImagePlugin)

组件:

<template>
	<div>
		<v-lazy-image :src="product_image" :src-placeholder="lazyPlaceholder"/>
		<v-lazy-image :src="product_image" :src-placeholder="lazyPlaceholder"/>
		<v-lazy-image :src="product_image" :src-placeholder="lazyPlaceholder"/>
	</div>
</template>
<script>
export default {
	data () {
		product_image: 'http://img.alicdn.com/imgextra/i1/3990548613/O1CN01VxNcOn2DUnnBu8jIW_!!0-item_pic.jpg',
		lazyPlaceholder: require('./lazy-placeholder.png')
	},
	mounted () {
		// ...
	}
}
</script>

修改后的插件源码:plugins/VLazyImage

const VLazyImageComponent = {
  props: {
    src: {
      type: String,
      required: true
    },
    srcPlaceholder: {
      type: String,
      default: ''
    },
    srcset: {
      type: String
    },
    intersectionOptions: {
      type: Object,
      default: () => ({})
    },
    usePicture: {
      type: Boolean,
      default: false
    }
  },
  inheritAttrs: false,
  data: () => ({ observer: null, intersected: false, loaded: false }),
  computed: {
    srcImage () {
      return this.intersected ? this.src : this.srcPlaceholder
    },
    srcsetImage () {
      return this.intersected && this.srcset ? this.srcset : false
    }
  },
  methods: {
    load () {
      if (this.$el.getAttribute('src') !== this.srcPlaceholder) {
        this.loaded = true
        this.$emit('load')
      }
    }
  },
  render (h) {
    let img = h('img', {
      attrs: {
        src: this.srcImage,
        srcset: this.srcsetImage
      },
      domProps: this.$attrs,
      class: {
        'v-lazy-image': true,
        'v-lazy-image-loaded': this.loaded
      },
      on: { load: this.load }
    })
    if (this.usePicture) {
      return h('picture', { on: { load: this.load } }, this.intersected ? [ this.$slots.default, img ] : [])
    } else {
      return img
    }
  },
  mounted () {
    if ('IntersectionObserver' in window) {
      this.observer = new IntersectionObserver(entries => {
        const image = entries[0]
        if (image.isIntersecting || image.intersectionRatio) {
          this.intersected = true
          this.observer.disconnect()
          this.$emit('intersect')
        }
      }, this.intersectionOptions)
      this.observer.observe(this.$el)
    } else {
      console.error(
        "v-lazy-image: this browser doesn't support IntersectionObserver. Please use this polyfill to make it work https://github.com/w3c/IntersectionObserver/tree/master/polyfill."
      )
    }
  },
  destroyed () {
    this.observer.disconnect()
  }
}

export default VLazyImageComponent

export const VLazyImagePlugin = {
  install: (Vue, opts) => {
    Vue.component('VLazyImage', VLazyImageComponent)
  }
}

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