48 lines
1.1 KiB
JavaScript
48 lines
1.1 KiB
JavaScript
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import { Store } from 'svelte/store.js'
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import { splice } from 'svelte-extras'
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class VirtualListStore extends Store {
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}
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VirtualListStore.prototype.splice = splice
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const virtualListStore = new VirtualListStore({
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items: [],
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itemHeights: {},
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scrollTop: 0
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})
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virtualListStore.compute('virtualItems', ['items'], (items) => {
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return items.map((item, idx) => ({
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props: item.props,
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key: item.key,
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index: idx
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}))
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})
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virtualListStore.compute('itemOffsets', ['virtualItems', 'itemHeights'], (virtualItems, itemHeights) => {
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let itemOffsets = {}
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let totalHeight = 0
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virtualItems.forEach(item => {
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let height = itemHeights[item.key] || 0
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itemOffsets[item.key] = totalHeight
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totalHeight += height
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})
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return itemOffsets
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})
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virtualListStore.compute('height', ['virtualItems', 'itemHeights'], (virtualItems, itemHeights) => {
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let sum = 0
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virtualItems.forEach(item => {
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sum += itemHeights[item.key] || 0
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})
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return sum
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})
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if (process.browser && process.env.NODE_ENV !== 'production') {
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window.virtualListStore = virtualListStore
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}
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export {
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virtualListStore
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}
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