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