Dan Abramov
56 lines
1.4 KiB
TypeScript
56 lines
1.4 KiB
TypeScript
import {Image} from 'react-native'
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import type {Dimensions} from '#/lib/media/types'
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type CacheStorageItem<T> = {key: string; value: T}
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const createCache = <T>(cacheSize: number) => ({
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_storage: [] as CacheStorageItem<T>[],
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get(key: string) {
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const {value} =
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this._storage.find(({key: storageKey}) => storageKey === key) || {}
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return value
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},
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set(key: string, value: T) {
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if (this._storage.length >= cacheSize) {
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this._storage.shift()
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}
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this._storage.push({key, value})
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},
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})
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const sizes = createCache<Dimensions>(50)
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const activeRequests: Map<string, Promise<Dimensions>> = new Map()
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export function get(uri: string): Dimensions | undefined {
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return sizes.get(uri)
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}
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export function fetch(uri: string): Promise<Dimensions> {
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const dims = sizes.get(uri)
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if (dims) {
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return Promise.resolve(dims)
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}
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const activeRequest = activeRequests.get(uri)
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if (activeRequest) {
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return activeRequest
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}
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const prom = new Promise<Dimensions>((resolve, reject) => {
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Image.getSize(
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uri,
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(width: number, height: number) => {
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const size = {width, height}
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sizes.set(uri, size)
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resolve(size)
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},
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(err: any) => {
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console.error('Failed to fetch image dimensions for', uri, err)
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reject(new Error('Could not fetch dimensions'))
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},
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)
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}).finally(() => {
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activeRequests.delete(uri)
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})
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activeRequests.set(uri, prom)
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return prom
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}
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