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9 months ago
<template>
<u-transition
mode="fade"
:customStyle="backTopStyle"
:show="show"
>
<view
class="u-back-top"
:style="[contentStyle]"
v-if="!$slots.default && !$slots.$default"
@click="backToTop"
>
<u-icon
:name="icon"
:custom-style="iconStyle"
></u-icon>
<text
v-if="text"
class="u-back-top__text"
>{{text}}</text>
</view>
<slot v-else />
</u-transition>
</template>
<script>
import props from './props.js';
// #ifdef APP-NVUE
const dom = weex.requireModule('dom')
// #endif
/**
* backTop 返回顶部
* @description 本组件一个用于长页面滑动一定距离后出现返回顶部按钮方便快速返回顶部的场景
* @tutorial https://uviewui.com/components/backTop.html
*
* @property {String} mode 返回顶部的形状circle-圆形square-方形 默认 'circle'
* @property {String} icon 自定义图标 默认 'arrow-upward' 见官方文档示例
* @property {String} text 提示文字
* @property {String | Number} duration 返回顶部滚动时间 默认 100
* @property {String | Number} scrollTop 滚动距离 默认 0
* @property {String | Number} top 距离顶部多少距离显示单位px 默认 400
* @property {String | Number} bottom 返回顶部按钮到底部的距离单位px 默认 100
* @property {String | Number} right 返回顶部按钮到右边的距离单位px 默认 20
* @property {String | Number} zIndex 层级 默认 9
* @property {Object<Object>} iconStyle 图标的样式对象形式 默认 {color: '#909399',fontSize: '19px'}
* @property {Object} customStyle 定义需要用到的外部样式
*
* @example <u-back-top :scrollTop="scrollTop"></u-back-top>
*/
export default {
name: 'u-back-top',
mixins: [uni.$u.mpMixin, uni.$u.mixin,props],
computed: {
backTopStyle() {
// 动画组件样式
const style = {
bottom: uni.$u.addUnit(this.bottom),
right: uni.$u.addUnit(this.right),
width: '40px',
height: '40px',
position: 'fixed',
zIndex: 10,
}
return style
},
show() {
return uni.$u.getPx(this.scrollTop) > uni.$u.getPx(this.top)
},
contentStyle() {
const style = {}
let radius = 0
// 是否圆形
if(this.mode === 'circle') {
radius = '100px'
} else {
radius = '4px'
}
// 为了兼容安卓nvue,只能这么分开写
style.borderTopLeftRadius = radius
style.borderTopRightRadius = radius
style.borderBottomLeftRadius = radius
style.borderBottomRightRadius = radius
return uni.$u.deepMerge(style, uni.$u.addStyle(this.customStyle))
}
},
methods: {
backToTop() {
// #ifdef APP-NVUE
if (!this.$parent.$refs['u-back-top']) {
uni.$u.error(`nvue页面需要给页面最外层元素设置"ref='u-back-top'`)
}
dom.scrollToElement(this.$parent.$refs['u-back-top'], {
offset: 0
})
// #endif
// #ifndef APP-NVUE
uni.pageScrollTo({
scrollTop: 0,
duration: this.duration
});
// #endif
this.$emit('click')
}
}
}
</script>
<style lang="scss" scoped>
@import '../../libs/css/components.scss';
$u-back-top-flex:1 !default;
$u-back-top-height:100% !default;
$u-back-top-background-color:#E1E1E1 !default;
$u-back-top-tips-font-size:12px !default;
.u-back-top {
@include flex;
flex-direction: column;
align-items: center;
flex:$u-back-top-flex;
height: $u-back-top-height;
justify-content: center;
background-color: $u-back-top-background-color;
&__tips {
font-size:$u-back-top-tips-font-size;
transform: scale(0.8);
}
}
</style>