pinafore/routes/_components/virtualList/VirtualList.html

95 lines
2.9 KiB
HTML

<!-- TODO: setting height is hacky, just make this element the scroller -->
<div class="virtual-list {{shown ? '' : 'hidden'}}" style="height: {{$height}}px;">
{{#if $visibleItems}}
{{#each $visibleItems as visibleItem @key}}
<VirtualListLazyItem :component
offset="{{visibleItem.offset}}"
makeProps="{{makeProps}}"
key="{{visibleItem.key}}"
index="{{visibleItem.index}}"
/>
{{/each}}
{{/if}}
{{#if $showFooter}}
<VirtualListFooter component="{{footerComponent}}"/>
{{/if}}
</div>
<style>
.virtual-list {
position: relative;
transition: opacity 0.25s linear;
}
</style>
<script>
import VirtualListLazyItem from './VirtualListLazyItem'
import VirtualListFooter from './VirtualListFooter.html'
import { virtualListStore } from './virtualListStore'
import throttle from 'lodash/throttle'
import { mark, stop } from '../../_utils/marks'
const DISTANCE_FROM_BOTTOM_TO_FIRE = 400
const SCROLL_TO_BOTTOM_DELAY = 1000
export default {
oncreate () {
this.observeSafely('showFooter', showFooter => {
this.store.setForRealm({showFooter: showFooter})
})
this.observeSafely('items', (items) => {
mark('set items')
this.store.setForRealm({items: items})
stop('set items')
this.fireScrollToBottom = throttle(() => {
this.fire('scrollToBottom')
}, SCROLL_TO_BOTTOM_DELAY)
})
this.observeSafely('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight => {
if (allVisibleItemsHaveHeight) {
this.fire('initializedVisibleItems')
}
})
let observedOnce = false
this.observeSafely('distanceFromBottom', (distanceFromBottom) => {
if (!observedOnce) {
observedOnce = true // TODO: the first time is always 0... need better way to handle this
return
}
if (distanceFromBottom >= 0 &&
distanceFromBottom <= DISTANCE_FROM_BOTTOM_TO_FIRE) {
this.fireScrollToBottom()
}
})
},
data: () => ({
component: null
}),
store: () => virtualListStore,
components: {
VirtualListLazyItem,
VirtualListFooter
},
computed: {
distanceFromBottom: ($scrollHeight, $scrollTop, $offsetHeight) => {
return $scrollHeight - $scrollTop - $offsetHeight
},
// TODO: bug in svelte store, shouldn't need to do this
allVisibleItemsHaveHeight: ($allVisibleItemsHaveHeight) => $allVisibleItemsHaveHeight
},
ondestroy() {
this.__destroyed = true
},
methods: {
observeSafely(val, callback) {
// TODO: feels like this shouldn't be necessary... bug in Svelte?
this.observe(val, val => {
if (!this.__destroyed) {
callback(val)
}
})
}
}
}
</script>