64 lines
1.5 KiB
Swift
64 lines
1.5 KiB
Swift
#if os(iOS)
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import UIKit
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public typealias PlatformImage = UIImage
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#elseif os(macOS)
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import AppKit
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public typealias PlatformImage = NSImage
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#endif
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/// Reference: https://www.onswiftwings.com/posts/reusable-image-cache/
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public final class ImageCache {
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public static let shared = ImageCache()
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public subscript(_ key: URL) -> PlatformImage? {
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get {
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image(key)
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}
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set {
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insertImage(newValue, url: key)
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}
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}
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public func removeAllObjects() {
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cache.removeAllObjects()
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}
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private let queue = DispatchQueue(label: "app.omnivore.image.cache.queue", attributes: .concurrent)
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private let cache = NSCache<AnyObject, PlatformImage>()
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private init() {
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cache.totalCostLimit = 1024 * 1024 * 50 // 50 MB
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}
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private func image(_ url: URL) -> PlatformImage? {
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var cachedImage: PlatformImage?
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queue.sync {
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cachedImage = cache.object(forKey: url as AnyObject)
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}
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return cachedImage
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}
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private func insertImage(_ image: PlatformImage?, url: URL) {
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guard let image = image else { return }
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queue.async(flags: .barrier) {
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self.cache.setObject(image, forKey: url as AnyObject, cost: image.diskSize)
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}
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}
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}
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private extension PlatformImage {
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var diskSize: Int {
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#if os(iOS)
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guard let cgImage = cgImage else { return 0 }
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return cgImage.bytesPerRow * cgImage.height
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#elseif os(macOS)
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// Instead of calculating the nsimage size just assume 250k
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// which will allow for up to 200 images in the cache
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(1024 * 1024) / 4
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#endif
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}
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}
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