pinafore/routes/_components/VirtualList.html

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<!-- TODO: setting height is hacky, just make this element the scroller -->
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<div class="virtual-list {{shown ? '' : 'hidden'}}" style="height: {{$height}}px;">
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{{#each $visibleItems as item @key}}
<VirtualListItem :component
offset="{{item.offset}}"
props="{{item.props}}"
key="{{item.key}}"
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index="{{item.index}}"
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/>
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{{/each}}
</div>
<style>
.virtual-list {
position: relative;
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transition: opacity 0.25s linear;
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}
</style>
<script>
import VirtualListItem from './VirtualListItem'
import { virtualListStore } from '../_utils/virtualListStore'
import throttle from 'lodash/throttle'
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import { mark, stop } from '../_utils/marks'
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const DISTANCE_FROM_BOTTOM_TO_FIRE = 400
const SCROLL_TO_BOTTOM_DELAY = 1000
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export default {
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oncreate () {
this.observe('items', (items) => {
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mark('set items')
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this.store.set({
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items: items
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})
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stop('set items')
this.fireScrollToBottom = throttle(() => {
this.fire('scrollToBottom')
}, SCROLL_TO_BOTTOM_DELAY)
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})
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let observedOnce = false
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this.observe('distanceFromBottom', (distanceFromBottom) => {
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if (!observedOnce) {
observedOnce = true // TODO: the first time is always 0... need better way to handle this
return
}
if (distanceFromBottom >= 0 &&
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distanceFromBottom <= DISTANCE_FROM_BOTTOM_TO_FIRE) {
this.fireScrollToBottom()
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}
})
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},
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data: () => ({
component: null
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}),
store: () => virtualListStore,
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components: {
VirtualListItem
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},
computed: {
distanceFromBottom: ($scrollHeight, $scrollTop, $offsetHeight) => {
return $scrollHeight - $scrollTop - $offsetHeight
}
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}
}
</script>