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10 months ago
<template>
<view class="u-wrap" :style="{
opacity: Number(opacity),
borderRadius: borderRadius + 'rpx',
// 因为time值需要改变,所以不直接用duration值(不能改变父组件prop传过来的值)
transition: `opacity ${time / 1000}s ease-in-out`
}"
:class="'u-lazy-item-' + elIndex">
<view :class="'u-lazy-item-' + elIndex">
<image :style="{borderRadius: borderRadius + 'rpx', height: imgHeight}" v-if="!isError" class="u-lazy-item"
:src="isShow ? image : loadingImg" :mode="imgMode" @load="imgLoaded" @error="loadError" @tap="clickImg"></image>
<image :style="{borderRadius: borderRadius + 'rpx', height: imgHeight}" class="u-lazy-item error" v-else :src="errorImg"
:mode="imgMode" @load="errorImgLoaded" @tap="clickImg"></image>
</view>
</view>
</template>
<script>
/**
* lazyLoad 懒加载
* @description 懒加载使用的场景为页面有很多图片时APP会同时加载所有的图片导致页面卡顿各个位置的图片出现前后不一致等.
* @tutorial https://www.uviewui.com/components/lazyLoad.html
* @property {String Number} index 用户自定义值在事件触发时回调用以区分是哪个图片
* @property {String} image 图片路径
* @property {String} loading-img 预加载时的占位图
* @property {String} error-img 图片加载出错时的占位图
* @property {String} threshold 触发加载时的位置见上方说明单位 rpx默认300
* @property {String Number} duration 图片加载成功时淡入淡出时间单位ms默认
* @property {String} effect 图片加载成功时淡入淡出的css动画效果默认ease-in-out
* @property {Boolean} is-effect 图片加载成功时是否启用淡入淡出效果默认true
* @property {String Number} border-radius 图片圆角值单位rpx默认0
* @property {String Number} height 图片高度注意实际高度可能受img-mode参数影响默认450
* @property {String Number} mg-mode 图片的裁剪模式详见image组件裁剪模式默认widthFix
* @event {Function} click 点击图片时触发
* @event {Function} load 图片加载成功时触发
* @event {Function} error 图片加载失败时触发
* @example <u-lazy-load :image="image" :loading-img="loadingImg" :error-img="errorImg"></u-lazy-load>
*/
export default {
name: 'u-lazy-load',
emits: ["click", "load", "error"],
props: {
index: {
type: [Number, String]
},
// 要显示的图片
image: {
type: String,
default: ''
},
// 图片裁剪模式
imgMode: {
type: String,
default: 'widthFix'
},
// 占位图片路径
loadingImg: {
type: String,
default: 'data:image/png;base64,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'
},
// 加载失败的错误占位图
errorImg: {
type: String,
default: 'data:image/png;base64,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
},
// 图片进入可见区域前多少像素时,单位rpx,开始加载图片
// 负数为图片超出屏幕底部多少距离后触发懒加载,正数为图片顶部距离屏幕底部多少距离时触发(图片还没出现在屏幕上)
threshold: {
type: [Number, String],
default: 100
},
// 淡入淡出动画的过渡时间
duration: {
type: [Number, String],
default: 500
},
// 渡效果的速度曲线,各个之间差别不大,因为这是淡入淡出,且时间很短,不是那些变形或者移动的情况,会明显
// linear|ease|ease-in|ease-out|ease-in-out|cubic-bezier(n,n,n,n);
effect: {
type: String,
default: 'ease-in-out'
},
// 是否使用过渡效果
isEffect: {
type: Boolean,
default: true
},
// 圆角值
borderRadius: {
type: [Number, String],
default: 0
},
// 图片高度,单位rpx
height: {
type: [Number, String],
default: '450'
}
},
data() {
return {
isShow: false,
opacity: 1,
time: this.duration,
loadStatus: '', // 默认是懒加载中的状态
isError: false, // 图片加载失败
elIndex: this.$u.guid()
}
},
computed: {
// 将threshold从rpx转为px
getThreshold() {
// 先取绝对值,因为threshold可能是负数,最后根据this.threshold是正数或者负数,重新还原
let thresholdPx = uni.upx2px(Math.abs(this.threshold));
return this.threshold < 0 ? -thresholdPx : thresholdPx;
},
// 计算图片的高度,可能为auto,带%,或者直接数值
imgHeight() {
return this.$u.addUnit(this.height);
}
},
created() {
// 由于一些特殊原因,不能将此变量放到data中定义
this.observer = {};
},
watch: {
isShow(nVal) {
// 如果是不开启过渡效果,直接返回
if (!this.isEffect) return;
this.time = 0;
// 原来opacity为1(不透明,是为了显示占位图),改成0(透明,意味着该元素显示的是背景颜色,默认的白色),再改成1,是为了获得过渡效果
this.opacity = 0;
// 延时30ms,否则在浏览器H5,过渡效果无效
setTimeout(() => {
this.time = this.duration;
this.opacity = 1;
}, 30)
},
// 图片路径发生变化时,需要重新标记一些变量,否则会一直卡在某一个状态,比如isError
image(n) {
if(!n) {
// 如果传入null或者'',或者undefined,标记为错误状态
this.isError = true;
} else {
this.init();
this.isError = false;
}
}
},
methods: {
// 用于重新初始化
init() {
this.isError = false;
this.loadStatus = '';
},
// 点击图片触发的事件,loadlazy-还是懒加载中状态,loading-图片正在加载,loaded-图片加加载完成
clickImg() {
let whichImg = '';
// 如果isShow为false,意味着图片还没开始加载,点击的只能是最开始的占位图
if (this.isShow == false) whichImg = 'lazyImg';
// 如果isError为true,意味着图片加载失败,这是只剩下错误的占位图,所以点击的只能是错误占位图
// 当然,也可以给错误的占位图元素绑定点击事件,看你喜欢~
else if (this.isError == true) whichImg = 'errorImg';
// 总共三张图片,除了两个占位图,剩下的只能是正常的那张图片了
else whichImg = 'realImg';
// 只通知当前图片的index
this.$emit('click', this.index);
},
// 图片加载完成事件,可能是加载占位图时触发,也可能是加载真正的图片完成时触发,通过isShow区分
imgLoaded() {
// 占位图加载完成
if (this.loadStatus == '') {
this.loadStatus = 'lazyed';
}
// 真正的图片加载完成
else if (this.loadStatus == 'lazyed') {
this.loadStatus = 'loaded';
this.$emit('load', this.index);
}
},
// 错误的图片加载完成
errorImgLoaded() {
this.$emit('error', this.index);
},
// 图片加载失败
loadError() {
this.isError = true;
},
disconnectObserver(observerName) {
const observer = this[observerName];
observer && observer.disconnect();
},
},
// #ifndef VUE3
// 组件销毁前,将实例从u-form的缓存中移除
beforeDestroy() {
// 销毁页面时,可能还没触发某张很底部的懒加载图片,所以把这个事件给去掉
//observer.disconnect();
},
// #endif
// #ifdef VUE3
beforeUnmount() {
},
// #endif
mounted() {
// 此uOnReachBottom事件由mixin.js发出,目的是让页面到底时,保证所有图片都进行加载,做到绝对稳定且可靠
this.$nextTick(() => {
uni.$once('uOnReachBottom', () => {
if (!this.isShow) this.isShow = true;
});
})
// mounted的时候,不一定挂载了这个元素,延时30ms,否则会报错或者不报错,但是也没有效果
setTimeout(() => {
// 这里是组件内获取布局状态,不能用uni.createIntersectionObserver,而必须用this.createIntersectionObserver
this.disconnectObserver('contentObserver');
const contentObserver = uni.createIntersectionObserver(this);
// 要理解这里怎么计算的,请看这个:
// https://blog.csdn.net/qq_25324335/article/details/83687695
contentObserver.relativeToViewport({
bottom: this.getThreshold,
}).observe('.u-lazy-item-' + this.elIndex, (res) => {
if (res.intersectionRatio > 0) {
// 懒加载状态改变
this.isShow = true;
// 如果图片已经加载,去掉监听,减少性能的消耗
this.disconnectObserver('contentObserver');
}
})
this.contentObserver = contentObserver;
}, 30)
}
}
</script>
<style scoped lang="scss">
@import "../../libs/css/style.components.scss";
.u-wrap {
background-color: #eee;
overflow: hidden;
}
.u-lazy-item {
width: 100%;
// 骗系统开启硬件加速
transform: transition3d(0, 0, 0);
// 防止图片加载“闪一下”
will-change: transform;
/* #ifndef APP-NVUE */
display: block;
/* #endif */
}
</style>