<template>
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<el-scrollbar ref="scrollContainer" :vertical="false" class="scroll-container" @wheel.native.prevent="handleScroll">
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<slot />
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</el-scrollbar>
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</template>
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<script>
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const tagAndTagSpacing = 4
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export default {
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name: 'ScrollPane',
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data() {
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return {
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left: 0
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}
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},
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computed: {
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scrollWrapper() {
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return this.$refs.scrollContainer.$refs.wrap
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}
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},
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mounted() {
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this.scrollWrapper.addEventListener('scroll', this.emitScroll, true)
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},
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beforeDestroy() {
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this.scrollWrapper.removeEventListener('scroll', this.emitScroll)
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},
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methods: {
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smoothScrollTo(target) {
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const $scrollWrapper = this.scrollWrapper
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const start = $scrollWrapper.scrollLeft
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const distance = target - start
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const duration = 300
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let startTime = null
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function ease(t, b, c, d) {
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t /= d / 2
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if (t < 1) return c / 2 * t * t + b
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t--
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return -c / 2 * (t * (t - 2) - 1) + b
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}
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const emit = this.$emit.bind(this)
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function step(timestamp) {
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if (!startTime) startTime = timestamp
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const elapsed = timestamp - startTime
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$scrollWrapper.scrollLeft = ease(elapsed, start, distance, duration)
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if (elapsed < duration) {
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requestAnimationFrame(step)
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} else {
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$scrollWrapper.scrollLeft = target
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emit('updateArrows')
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}
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}
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requestAnimationFrame(step)
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},
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handleScroll(e) {
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const eventDelta = e.wheelDelta || -e.deltaY * 40
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const $scrollWrapper = this.scrollWrapper
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$scrollWrapper.scrollLeft = $scrollWrapper.scrollLeft + eventDelta / 4
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this.$emit('updateArrows')
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},
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emitScroll() {
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this.$emit('scroll')
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this.$emit('updateArrows')
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},
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moveToTarget(currentTag) {
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const $container = this.$refs.scrollContainer.$el
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const $containerWidth = $container.offsetWidth
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const $scrollWrapper = this.scrollWrapper
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const tagList = this.$parent.$refs.tag
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let firstTag = null
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let lastTag = null
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if (tagList.length > 0) {
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firstTag = tagList[0]
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lastTag = tagList[tagList.length - 1]
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}
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if (firstTag === currentTag) {
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this.smoothScrollTo(0)
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} else if (lastTag === currentTag) {
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this.smoothScrollTo($scrollWrapper.scrollWidth - $containerWidth)
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} else {
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const currentIndex = tagList.findIndex(item => item === currentTag)
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const prevTag = tagList[currentIndex - 1]
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const nextTag = tagList[currentIndex + 1]
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const afterNextTagOffsetLeft = nextTag.$el.offsetLeft + nextTag.$el.offsetWidth + tagAndTagSpacing
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const beforePrevTagOffsetLeft = prevTag.$el.offsetLeft - tagAndTagSpacing
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if (afterNextTagOffsetLeft > $scrollWrapper.scrollLeft + $containerWidth) {
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this.smoothScrollTo(afterNextTagOffsetLeft - $containerWidth)
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} else if (beforePrevTagOffsetLeft < $scrollWrapper.scrollLeft) {
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this.smoothScrollTo(beforePrevTagOffsetLeft)
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}
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}
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},
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// 向左滚动固定距离
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scrollLeft() {
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const $scrollWrapper = this.scrollWrapper
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this.smoothScrollTo(Math.max(0, $scrollWrapper.scrollLeft - 200))
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},
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// 向右滚动固定距离
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scrollRight() {
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const $scrollWrapper = this.scrollWrapper
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const maxScroll = $scrollWrapper.scrollWidth - $scrollWrapper.clientWidth
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this.smoothScrollTo(Math.min(maxScroll, $scrollWrapper.scrollLeft + 200))
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},
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// 直接平滑滚动到最左端
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scrollToStart() {
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this.smoothScrollTo(0)
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},
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// 直接平滑滚动到最右端
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scrollToEnd() {
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const $scrollWrapper = this.scrollWrapper
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this.smoothScrollTo($scrollWrapper.scrollWidth - $scrollWrapper.clientWidth)
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},
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// 获取是否可以继续向左/右滚动
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getScrollState() {
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const $scrollWrapper = this.scrollWrapper
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return {
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canLeft: $scrollWrapper.scrollLeft > 0,
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canRight: $scrollWrapper.scrollLeft < $scrollWrapper.scrollWidth - $scrollWrapper.clientWidth - 1
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}
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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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.scroll-container {
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white-space: nowrap;
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position: relative;
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overflow: hidden;
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width: 100%;
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::v-deep {
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.el-scrollbar__bar {
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bottom: 0px;
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}
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.el-scrollbar__wrap {
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height: 34px;
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display: flex;
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align-items: center;
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}
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}
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}
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</style>
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