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<template>
<view class="">
<view class="u-sticky-wrap" :class="[elClass]" :style="{
height: fixed ? height + 'px' : 'auto',
backgroundColor: bgColor
}">
<view class="u-sticky" :style="{
position: fixed ? 'fixed' : 'static',
top: stickyTop + 'px',
left: left + 'px',
width: width == 'auto' ? 'auto' : width + 'px',
zIndex: uZIndex
}">
<slot></slot>
</view>
</view>
</view>
</template>
<script>
/**
* sticky 吸顶
* @description 该组件与CSS中position: sticky属性实现的效果一致,当组件达到预设的到顶部距离时, 就会固定在指定位置,组件位置大于预设的顶部距离时,会重新按照正常的布局排列。
* @tutorial https://www.uviewui.com/components/sticky.html
* @property {String Number} offset-top 吸顶时与顶部的距离,单位rpx(默认0)
* @property {String Number} index 自定义标识,用于区分是哪一个组件
* @property {Boolean} enable 是否开启吸顶功能(默认true)
* @property {String} bg-color 组件背景颜色(默认#ffffff)
* @property {String Number} z-index 吸顶时的z-index值(默认970)
* @property {String Number} h5-nav-height 导航栏高度,自定义导航栏时(无导航栏时需设置为0),需要传入此值,单位px(默认44)
* @event {Function} fixed 组件吸顶时触发
* @event {Function} unfixed 组件取消吸顶时触发
* @example <u-sticky offset-top="200"><view>塞下秋来风景异,衡阳雁去无留意</view></u-sticky>
*/
export default {
name: "u-sticky",
emits: ["fixed", "unfixed"],
props: {
// 吸顶容器到顶部某个距离的时候,进行吸顶,在H5平台,NavigationBar为44px
offsetTop: {
type: [Number, String],
default: 0
},
//列表中的索引值
index: {
type: [Number, String],
default: ''
},
// 是否开启吸顶功能
enable: {
type: Boolean,
default: true
},
// h5顶部导航栏的高度
h5NavHeight: {
type: [Number, String],
default: 44
},
// 吸顶区域的背景颜色
bgColor: {
type: String,
default: '#ffffff'
},
// z-index值
zIndex: {
type: [Number, String],
default: ''
}
},
data() {
return {
fixed: false,
height: 'auto',
stickyTop: 0,
elClass: this.$u.guid(),
left: 0,
width: 'auto',
};
},
watch: {
offsetTop(val) {
this.initObserver();
},
enable(val) {
if (val == false) {
this.fixed = false;
this.disconnectObserver('contentObserver');
} else {
this.initObserver();
}
}
},
computed: {
uZIndex() {
return this.zIndex ? this.zIndex : this.$u.zIndex.sticky;
}
},
mounted() {
this.initObserver();
},
methods: {
initObserver() {
if (!this.enable) return;
// #ifdef H5
this.stickyTop = this.offsetTop != 0 ? uni.upx2px(this.offsetTop) + this.h5NavHeight : this.h5NavHeight;
// #endif
// #ifndef H5
this.stickyTop = this.offsetTop != 0 ? uni.upx2px(this.offsetTop) : 0;
// #endif
this.disconnectObserver('contentObserver');
this.$uGetRect('.' + this.elClass).then((res) => {
this.height = res.height;
this.left = res.left;
this.width = res.width;
this.$nextTick(() => {
this.observeContent();
});
});
},
observeContent() {
this.disconnectObserver('contentObserver');
const contentObserver = uni.createIntersectionObserver(this,{
thresholds: [0.95, 0.98, 1]
});
contentObserver.relativeToViewport({
top: -this.stickyTop
});
contentObserver.observe('.' + this.elClass, res => {
if (!this.enable) return;
this.setFixed(res.boundingClientRect.top);
});
this.contentObserver = contentObserver;
},
setFixed(top) {
const fixed = top < this.stickyTop;
if (fixed) this.$emit('fixed', this.index);
else if(this.fixed) this.$emit('unfixed', this.index);
this.fixed = fixed;
},
disconnectObserver(observerName) {
const observer = this[observerName];
observer && observer.disconnect();
},
},
// #ifndef VUE3
beforeDestroy() {
this.disconnectObserver('contentObserver');
},
// #endif
// #ifdef VUE3
beforeUnmount() {
this.disconnectObserver('contentObserver');
},
// #endif
};
</script>
<style scoped lang="scss">
@import "../../libs/css/style.components.scss";
.u-sticky {
z-index: 9999999999;
}
</style>