pinafore/routes/_components/virtualList/VirtualListItem.html

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<div class="virtual-list-item {{shown ? 'shown' : ''}}"
virtual-list-key="{{key}}"
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ref:node
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style="transform: translateY({{offset}}px);" >
<:Component {component}
virtualProps="{{props}}"
virtualIndex="{{index}}"
virtualLength="{{$numItems}}"
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on:recalculateHeight="doRecalculateHeight()"/>
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</div>
<style>
.virtual-list-item {
position: absolute;
top: 0;
opacity: 0;
pointer-events: none;
}
.virtual-list-item.shown {
opacity: 1;
pointer-events: auto;
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}
</style>
<script>
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import { virtualListStore } from './virtualListStore'
import { AsyncLayout } from '../../_utils/AsyncLayout'
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export default {
oncreate() {
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this.doRecalculateHeight()
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},
store: () => virtualListStore,
computed: {
'shown': ($itemHeights, key) => $itemHeights[key] > 0
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},
methods: {
doRecalculateHeight() {
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let asyncLayout = new AsyncLayout(node => node.getAttribute('virtual-list-key'))
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let key = this.get('key')
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asyncLayout.observe(key, this.refs.node, (rect) => {
asyncLayout.disconnect()
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// update all item heights in one microtask batch for better perf
this.store.batchUpdate('itemHeights', key, rect.height)
})
}
}
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}
</script>