121 行
无行尾
4.1 KiB
HTML
121 行
无行尾
4.1 KiB
HTML
<slot></slot>
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<script>
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import { virtualListStore } from './virtualListStore'
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import throttle from 'lodash-es/throttle'
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import { isFullscreen, attachFullscreenListener, detachFullscreenListener } from '../../_utils/fullscreen'
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import { mark, stop } from '../../_utils/marks'
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import { scheduleIdleTask } from '../../_utils/scheduleIdleTask'
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import { isMobile } from '../../_utils/isMobile'
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import { doubleRAF } from '../../_utils/doubleRAF'
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import { observe } from 'svelte-extras'
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const SCROLL_EVENT_DELAY = 300
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export default {
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oncreate () {
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mark('onCreate VirtualListContainer')
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let {
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realm,
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containerQuery
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} = this.get()
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this.store.setCurrentRealm(realm)
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let node = document.querySelector(containerQuery)
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this.setupScroll(node)
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this.setupFullscreen()
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let { scrollTop } = this.store.get()
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if (scrollTop > 0) {
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this.observe('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight => {
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console.log('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight)
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let { initializedScrollTop } = this.get()
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if (!initializedScrollTop && allVisibleItemsHaveHeight && node) {
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this.set({'initializedScrollTop': true})
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mark('set scrollTop')
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console.log('forcing scroll top to ', scrollTop)
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node.scrollTop = scrollTop
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stop('set scrollTop')
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doubleRAF(() => {
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console.log('initialized VirtualList')
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this.fire('initialized')
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})
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}
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})
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} else {
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this.fire('noNeedToScroll')
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this.observe('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight => {
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if (allVisibleItemsHaveHeight) {
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console.log('initialized VirtualList')
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this.fire('initialized')
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}
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})
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this.store.setForRealm({
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scrollHeight: node.scrollHeight,
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offsetHeight: node.offsetHeight
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})
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}
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stop('onCreate VirtualListContainer')
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},
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ondestroy () {
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this.teardownScroll()
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this.teardownFullscreen()
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this.store.setCurrentRealm(null)
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},
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store: () => virtualListStore,
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methods: {
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observe,
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setupScroll (node) {
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if (!node) {
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return
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}
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this.scrollListener = throttle(event => {
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let { fullscreen } = this.get()
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if (fullscreen) {
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return
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}
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this.onScroll(event)
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}, SCROLL_EVENT_DELAY, {
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leading: true,
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trailing: true
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})
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node.addEventListener('scroll', this.scrollListener)
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},
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teardownScroll () {
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let { containerQuery } = this.get()
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let node = document.querySelector(containerQuery)
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if (node) {
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node.removeEventListener('scroll', this.scrollListener)
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}
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},
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setupFullscreen () {
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this.onFullscreenChange = this.onFullscreenChange.bind(this)
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attachFullscreenListener(this.onFullscreenChange)
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},
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teardownFullscreen () {
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detachFullscreenListener(this.onFullscreenChange)
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},
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onScroll (event) {
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let { scrollTop, scrollHeight } = event.target
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// On mobile devices, this can make scrolling more responsive. On
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// desktop browsers... it's probably overkill, and can lead to a
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// checkerboarding issue ("I just scrolled, why is it blank for 5 seconds?").
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let runTask = isMobile() ? scheduleIdleTask : requestAnimationFrame
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runTask(() => {
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mark('onScroll -> setForRealm()')
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this.store.setForRealm({scrollTop, scrollHeight})
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stop('onScroll -> setForRealm()')
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})
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},
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onFullscreenChange () {
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mark('onFullscreenChange')
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console.log('is fullscreen? ', isFullscreen())
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this.set({ fullscreen: isFullscreen() })
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stop('onFullscreenChange')
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}
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},
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computed: {
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// TODO: bug in svelte/store – the observer in oncreate() never get removed without this hack
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allVisibleItemsHaveHeight: ({ $allVisibleItemsHaveHeight }) => $allVisibleItemsHaveHeight
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}
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}
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</script> |