forked from zelo72/mastodon-ios
83 lines
2.6 KiB
Swift
83 lines
2.6 KiB
Swift
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// BlurhashImageCacheService.swift
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// Mastodon
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//
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// Created by MainasuK Cirno on 2021-6-16.
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//
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import UIKit
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import Combine
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final class BlurhashImageCacheService {
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let cache = NSCache<Key, UIImage>()
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let workingQueue = DispatchQueue(label: "org.joinmastodon.app.BlurhashImageCacheService.working-queue", qos: .userInitiated, attributes: .concurrent)
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func image(blurhash: String, size: CGSize, url: URL) -> AnyPublisher<UIImage?, Never> {
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return Future { promise in
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self.workingQueue.async {
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let key = Key(blurhash: blurhash, size: size, url: url)
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guard let image = self.cache.object(forKey: key) else {
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if let image = BlurhashImageCacheService.blurhashImage(blurhash: blurhash, size: size, url: url) {
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self.cache.setObject(image, forKey: key)
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promise(.success(image))
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} else {
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promise(.success(nil))
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}
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return
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}
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promise(.success(image))
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}
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}
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.eraseToAnyPublisher()
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}
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static func blurhashImage(blurhash: String, size: CGSize, url: URL) -> UIImage? {
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let imageSize: CGSize = {
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let aspectRadio = size.width / size.height
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if size.width > size.height {
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let width: CGFloat = MosaicMeta.edgeMaxLength
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let height = width / aspectRadio
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return CGSize(width: width, height: height)
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} else {
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let height: CGFloat = MosaicMeta.edgeMaxLength
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let width = height * aspectRadio
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return CGSize(width: width, height: height)
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}
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}()
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let image = UIImage(blurHash: blurhash, size: imageSize)
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return image
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}
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}
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extension BlurhashImageCacheService {
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class Key: Hashable {
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static func == (lhs: BlurhashImageCacheService.Key, rhs: BlurhashImageCacheService.Key) -> Bool {
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return lhs.blurhash == rhs.blurhash
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&& lhs.size == rhs.size
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&& lhs.url == rhs.url
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}
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let blurhash: String
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let size: CGSize
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let url: URL
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init(blurhash: String, size: CGSize, url: URL) {
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self.blurhash = blurhash
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self.size = size
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self.url = url
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}
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func hash(into hasher: inout Hasher) {
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hasher.combine(blurhash)
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hasher.combine(size.width)
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hasher.combine(size.height)
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hasher.combine(url)
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}
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}
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}
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