70 lines
1.7 KiB
Swift
70 lines
1.7 KiB
Swift
//
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// LoadImageOperation.swift
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// Delta
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//
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// Created by Riley Testut on 2/26/16.
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// Copyright © 2016 Riley Testut. All rights reserved.
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//
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import Foundation
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import ImageIO
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import Roxas
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class LoadImageOperation<CacheKeyType: AnyObject>: RSTOperation
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{
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var completionHandler: ((UIImage?) -> Void)? {
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didSet {
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self.completionBlock = {
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rst_dispatch_sync_on_main_thread() {
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self.completionHandler?(self.image)
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}
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}
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}
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}
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var imageCache: NSCache<CacheKeyType, UIImage>? {
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didSet {
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// Ensures if an image is cached, it will be returned immediately, to prevent temporary flash of placeholder image
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self.isImmediate = self.imageCache?.object(forKey: self.cacheKey) != nil
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}
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}
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private let cacheKey: CacheKeyType
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private var image: UIImage?
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init(cacheKey: CacheKeyType)
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{
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self.cacheKey = cacheKey
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super.init()
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}
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override func main()
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{
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guard !self.isCancelled else { return }
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if let cachedImage = self.imageCache?.object(forKey: self.cacheKey)
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{
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self.image = cachedImage
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return
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}
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guard let loadedImage = self.loadImage() else { return }
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// Force decompression of image
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UIGraphicsBeginImageContextWithOptions(CGSize(width: 1, height: 1), true, 1.0)
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loadedImage.draw(at: CGPoint.zero)
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UIGraphicsEndImageContext()
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self.imageCache?.setObject(loadedImage, forKey: self.cacheKey)
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self.image = loadedImage
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}
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func loadImage() -> UIImage?
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{
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return nil
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}
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}
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