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Pods/Kingfisher/Sources/Networking/ImageDataProcessor.swift

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+//
+//  ImageDataProcessor.swift
+//  Kingfisher
+//
+//  Created by Wei Wang on 2018/10/11.
+//
+//  Copyright (c) 2019 Wei Wang <onevcat@gmail.com>
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+
+import Foundation
+
+private let sharedProcessingQueue: CallbackQueue =
+    .dispatch(DispatchQueue(label: "com.onevcat.Kingfisher.ImageDownloader.Process"))
+
+// Handles image processing work on an own process queue.
+class ImageDataProcessor {
+    let data: Data
+    let callbacks: [SessionDataTask.TaskCallback]
+    let queue: CallbackQueue
+
+    // Note: We have an optimization choice there, to reduce queue dispatch by checking callback
+    // queue settings in each option...
+    let onImageProcessed = Delegate<(Result<KFCrossPlatformImage, KingfisherError>, SessionDataTask.TaskCallback), Void>()
+
+    init(data: Data, callbacks: [SessionDataTask.TaskCallback], processingQueue: CallbackQueue?) {
+        self.data = data
+        self.callbacks = callbacks
+        self.queue = processingQueue ?? sharedProcessingQueue
+    }
+
+    func process() {
+        queue.execute(doProcess)
+    }
+
+    private func doProcess() {
+        var processedImages = [String: KFCrossPlatformImage]()
+        for callback in callbacks {
+            let processor = callback.options.processor
+            var image = processedImages[processor.identifier]
+            if image == nil {
+                image = processor.process(item: .data(data), options: callback.options)
+                processedImages[processor.identifier] = image
+            }
+
+            let result: Result<KFCrossPlatformImage, KingfisherError>
+            if let image = image {
+                let finalImage = callback.options.backgroundDecode ? image.kf.decoded : image
+                result = .success(finalImage)
+            } else {
+                let error = KingfisherError.processorError(
+                    reason: .processingFailed(processor: processor, item: .data(data)))
+                result = .failure(error)
+            }
+            onImageProcessed.call((result, callback))
+        }
+    }
+}