44 lines
		
	
	
		
			No EOL
		
	
	
		
			1.2 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
			
		
		
	
	
			44 lines
		
	
	
		
			No EOL
		
	
	
		
			1.2 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: translate3d(0, {{offset}}px, 0);"
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>
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  <:Component {component} virtualProps="{{props}}" virtualIndex="{{index}}" virtualLength="{{$numItems}}"/>
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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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  .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 asyncLayout = new AsyncLayout(node => node.getAttribute('virtual-list-key'))
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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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  }
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</script> |