56 lines
1.7 KiB
HTML
56 lines
1.7 KiB
HTML
<div class="virtual-list-item {{shown ? 'shown' : ''}}"
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virtual-list-key="{{key}}"
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ref:node
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style="transform: translateY({{offset}}px);" >
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<:Component {component} virtualProps="{{props}}" virtualIndex="{{index}}" virtualLength="{{$numItems}}"
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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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top: 0;
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opacity: 0;
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pointer-events: none;
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/* will-change: transform; */ /* causes jank in mobile Firefox */
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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 '../_utils/virtualListStore'
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import { AsyncLayout } from '../_utils/AsyncLayout'
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const keyGetter = node => node.getAttribute('virtual-list-key')
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const asyncLayout = new AsyncLayout(keyGetter)
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export default {
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oncreate() {
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let key = this.get('key')
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asyncLayout.observe(key, this.refs.node, (rect) => {
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// update all item heights in one microtask batch for better perf
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this.store.batchUpdate('itemHeights', key, rect.height)
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})
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},
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ondestroy() {
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let key = this.get('key')
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asyncLayout.unobserve(key, this.refs.node)
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},
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store: () => virtualListStore,
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computed: {
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'shown': ($itemHeights, key) => $itemHeights[key] > 0
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},
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methods: {
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doRecalculateHeight() {
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let tempAsyncLayout = new AsyncLayout(keyGetter)
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let key = this.get('key')
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tempAsyncLayout.observe(key, this.refs.node, (rect) => {
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tempAsyncLayout.disconnect()
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// update all item heights in one microtask batch for better perf
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this.store.batchUpdate('itemHeights', key, rect.height)
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})
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}
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}
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}
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</script> |