|
- <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',
- 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();
- },
- },
- 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();
- },
- 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>
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