126 lines
3.9 KiB
HTML
126 lines
3.9 KiB
HTML
<VirtualListContainer {realm} on:initialized on:noNeedToScroll >
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<div class="virtual-list"
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style="height: {$height}px;"
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ref:node >
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<VirtualListHeader component={headerComponent} virtualProps={headerProps} shown={$showHeader}/>
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{#if $visibleItems}
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{#each $visibleItems as visibleItem (visibleItem.key)}
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<VirtualListLazyItem {component}
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offset={visibleItem.offset}
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{makeProps}
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key={visibleItem.key}
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index={visibleItem.index}
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/>
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{/each}
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{/if}
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{#if $showFooter}
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<VirtualListFooter component={footerComponent} />
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{/if}
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</div>
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</VirtualListContainer>
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<style>
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.virtual-list {
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position: relative;
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}
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</style>
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<script>
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import VirtualListContainer from './VirtualListContainer.html'
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import VirtualListLazyItem from './VirtualListLazyItem'
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import VirtualListFooter from './VirtualListFooter.html'
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import VirtualListHeader from './VirtualListHeader.html'
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import { virtualListStore } from './virtualListStore'
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import throttle from 'lodash-es/throttle'
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import { mark, stop } from '../../_utils/marks'
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import isEqual from 'lodash-es/isEqual'
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import { observe } from 'svelte-extras'
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const DISTANCE_FROM_BOTTOM_TO_FIRE = 800
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const SCROLL_EVENT_THROTTLE = 1000
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export default {
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oncreate () {
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this.fireScrollToBottom = throttle(() => {
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this.fire('scrollToBottom')
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}, SCROLL_EVENT_THROTTLE)
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this.fireScrollToTop = throttle(() => {
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this.fire('scrollToTop')
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}, SCROLL_EVENT_THROTTLE)
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this.observe('showFooter', showFooter => {
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mark('set showFooter')
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this.store.setForRealm({ showFooter: showFooter })
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mark('set showFooter')
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})
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this.observe('showHeader', showHeader => {
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mark('set showHeader')
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this.store.setForRealm({ showHeader: showHeader })
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stop('set showHeader')
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})
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this.observe('items', (newItems, oldItems) => {
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if (!newItems || isEqual(newItems, oldItems)) {
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return
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}
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mark('set items')
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this.store.setForRealm({ items: newItems })
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stop('set items')
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})
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this.observe('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight => {
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if (allVisibleItemsHaveHeight) {
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this.fire('initializedVisibleItems')
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}
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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) {
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observedOnce = true // TODO: the first time is always 0... need better way to handle this
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return
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}
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if (distanceFromBottom >= 0 &&
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distanceFromBottom <= DISTANCE_FROM_BOTTOM_TO_FIRE) {
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this.fireScrollToBottom()
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}
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})
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this.observe('scrollTop', (scrollTop) => {
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this.fire('scrollTopChanged', scrollTop)
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if (scrollTop === 0) {
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this.fireScrollToTop()
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}
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this.calculateListOffset()
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})
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},
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data: () => ({
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component: null
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}),
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store: () => virtualListStore,
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components: {
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VirtualListContainer,
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VirtualListLazyItem,
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VirtualListFooter,
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VirtualListHeader
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},
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computed: {
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distanceFromBottom: ({ $scrollHeight, $scrollTop, $offsetHeight }) => {
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return $scrollHeight - $scrollTop - $offsetHeight
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},
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scrollTop: ({ $scrollTop }) => $scrollTop,
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// TODO: bug in svelte store, shouldn't need to do this
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allVisibleItemsHaveHeight: ({ $allVisibleItemsHaveHeight }) => $allVisibleItemsHaveHeight
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},
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methods: {
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observe,
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calculateListOffset () {
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// TODO: better way to get the offset top?
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let node = this.refs.node
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if (!node) {
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return
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}
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mark('calculateListOffset')
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let listOffset = node.offsetParent.offsetTop
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this.store.setForRealm({ listOffset })
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stop('calculateListOffset')
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}
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}
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}
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</script> |