pinafore/routes/_components/virtualList/VirtualList.html
2018-12-04 07:24:55 -08:00

126 lines
3.9 KiB
HTML

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