82 lines
2.6 KiB
HTML
82 lines
2.6 KiB
HTML
<div class="virtual-list-item list-item {shown ? 'shown' : ''}"
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aria-hidden={!shown}
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ref:node
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style="transform: translateY({offset}px);" >
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<svelte:component this={component}
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virtualProps={props}
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virtualIndex={index}
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virtualLength={$length}
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virtualKey={key}
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on:recalculateHeight="doRecalculateHeight()"/>
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</div>
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<style>
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.virtual-list-item {
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position: absolute;
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width: 100%;
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top: 0;
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opacity: 0;
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pointer-events: none;
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transition: opacity 0.2s linear;
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contain: content; /* see https://www.w3.org/TR/2018/CR-css-contain-1-20181108/#valdef-contain-content */
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}
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.virtual-list-item.shown {
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opacity: 1;
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pointer-events: auto;
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}
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</style>
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<script>
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import { virtualListStore } from './virtualListStore'
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import { registerResizeListener, unregisterResizeListener } from '../../_utils/resize'
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import { mark, stop } from '../../_utils/marks'
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import { requestPostAnimationFrame } from '../../_utils/requestPostAnimationFrame'
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import { observe } from 'svelte-extras'
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import { doubleRAF } from '../../_utils/doubleRAF'
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export default {
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oncreate () {
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const { key } = this.get()
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const node = this.refs.node
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requestPostAnimationFrame(() => {
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if (!node || !key) {
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return
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}
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mark('VirtualListItem gBCR')
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const rect = node.getBoundingClientRect()
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stop('VirtualListItem gBCR')
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// update all item heights in one batch for better perf
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this.store.batchUpdateForRealm('itemHeights', key, rect.height)
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})
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this.doRecalculateHeight = this.doRecalculateHeight.bind(this)
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registerResizeListener(this.doRecalculateHeight)
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// this rAF delay is necessary in order to get the fade-in animation
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// to consistently show
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this.observe('shownBeforeRaf', shownBeforeRaf => {
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doubleRAF(() => {
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this.set({ shown: shownBeforeRaf })
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})
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})
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},
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ondestroy () {
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unregisterResizeListener(this.doRecalculateHeight)
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},
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store: () => virtualListStore,
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data: () => ({
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shown: false
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}),
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computed: {
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shownBeforeRaf: ({ $itemHeights, key }) => $itemHeights[key] > 0
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},
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methods: {
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observe,
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doRecalculateHeight () {
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// Recalculate immediately because this is done on-demand, e.g.
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// when clicking the "More" button on a spoiler.
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const rect = this.refs.node.getBoundingClientRect()
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const { key } = this.get()
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const { itemHeights } = this.store.get()
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itemHeights[key] = rect.height
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this.store.setForRealm({ itemHeights })
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}
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}
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}
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</script>
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