134 lines
No EOL
4.3 KiB
HTML
134 lines
No EOL
4.3 KiB
HTML
<div class="pseudo-virtual-list" on:initialized ref:node>
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{#each safeItems as item, i (item)}
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<PseudoVirtualListLazyItem
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{component}
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index={i}
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length={safeItems.length}
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{makeProps}
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key={item}
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{intersectionObserver}
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isIntersecting={isIntersecting(item, $intersectionStates)}
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isCached={isCached(item, $intersectionStates)}
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height={getHeight(item, $intersectionStates)}
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/>
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{/each}
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</div>
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<style>
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.pseudo-virtual-list {
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position: relative;
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}
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</style>
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<script>
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import PseudoVirtualListLazyItem from './PseudoVirtualListLazyItem.html'
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import { getRectFromEntry } from '../../_utils/getRectFromEntry'
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import { mark, stop } from '../../_utils/marks'
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import { pseudoVirtualListStore } from './pseudoVirtualListStore'
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import { observe } from 'svelte-extras'
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export default {
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oncreate () {
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mark('PseudoVirtualList oncreate()')
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let { realm } = this.get()
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this.store.setCurrentRealm(realm)
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// When re-rendering, assume all items are non-intersecting until told otherwise.
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// We already have the heights cached.
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let { intersectionStates } = this.store.get()
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let keys = Object.keys(intersectionStates)
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for (let key of keys) {
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intersectionStates[key].isCached = true
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}
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this.store.setForRealm({intersectionStates: intersectionStates})
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let { containerQuery } = this.get()
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let intersectionObserver = new IntersectionObserver(this.onIntersection.bind(this), {
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root: document.querySelector(containerQuery),
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rootMargin: '300% 0px'
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})
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this.set({intersectionObserver})
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this.observe('allItemsHaveHeight', allItemsHaveHeight => {
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console.log('allItemsHaveHeight', allItemsHaveHeight)
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let { initialized } = this.get()
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if (allItemsHaveHeight && !initialized) {
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this.set({initialized: true})
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console.log('initialized PseudoVirtualList')
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this.fire('initialized')
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}
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})
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stop('PseudoVirtualList oncreate()')
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},
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ondestroy () {
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let { intersectionObserver } = this.get()
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if (intersectionObserver) {
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intersectionObserver.disconnect()
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}
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this.store.setCurrentRealm(null)
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},
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helpers: {
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isIntersecting (key, $intersectionStates) {
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return !!($intersectionStates[key] && $intersectionStates[key].isIntersecting)
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},
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isCached (key, $intersectionStates) {
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return !!($intersectionStates[key] && $intersectionStates[key].isCached)
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},
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getHeight (key, $intersectionStates) {
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return $intersectionStates[key] && $intersectionStates[key].height
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}
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},
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methods: {
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observe,
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scrollToPosition (element) {
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let { scrolledToPosition } = this.get()
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if (scrolledToPosition) {
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return
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}
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this.set({scrolledToPosition: true})
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requestAnimationFrame(() => {
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console.log('scrolling element into view')
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element.scrollIntoView(true)
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})
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},
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onIntersection (entries) {
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mark('onIntersection')
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let newIntersectionStates = {}
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let { scrollToItem } = this.get()
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let { intersectionStates } = this.store.get()
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for (let entry of entries) {
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let key = entry.target.getAttribute('pseudo-virtual-list-key')
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let rect = getRectFromEntry(entry)
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newIntersectionStates[key] = {
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isIntersecting: entry.isIntersecting,
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height: rect.height
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}
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if (scrollToItem === key) {
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this.scrollToPosition(entry.target)
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}
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}
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intersectionStates = Object.assign(intersectionStates, newIntersectionStates)
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this.store.setForRealm({intersectionStates: intersectionStates})
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stop('onIntersection')
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}
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},
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computed: {
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safeItems: ({ items }) => items || [],
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allItemsHaveHeight: ({ items, $intersectionStates }) => {
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if (!items) {
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return false
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}
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for (let item of items) {
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if (!$intersectionStates[item]) {
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return false
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}
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}
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return true
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}
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},
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components: {
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PseudoVirtualListLazyItem
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},
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data: () => ({
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intersectionObserver: void 0
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}),
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store: () => pseudoVirtualListStore
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}
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</script> |