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Pods/Kingfisher/Sources/Image/GIFAnimatedImage.swift

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+//
+//  AnimatedImage.swift
+//  Kingfisher
+//
+//  Created by onevcat on 2018/09/26.
+//
+//  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
+import ImageIO
+
+/// Represents a set of image creating options used in Kingfisher.
+public struct ImageCreatingOptions {
+
+    /// The target scale of image needs to be created.
+    public let scale: CGFloat
+
+    /// The expected animation duration if an animated image being created.
+    public let duration: TimeInterval
+
+    /// For an animated image, whether or not all frames should be loaded before displaying.
+    public let preloadAll: Bool
+
+    /// For an animated image, whether or not only the first image should be
+    /// loaded as a static image. It is useful for preview purpose of an animated image.
+    public let onlyFirstFrame: Bool
+    
+    /// Creates an `ImageCreatingOptions` object.
+    ///
+    /// - Parameters:
+    ///   - scale: The target scale of image needs to be created. Default is `1.0`.
+    ///   - duration: The expected animation duration if an animated image being created.
+    ///               A value less or equal to `0.0` means the animated image duration will
+    ///               be determined by the frame data. Default is `0.0`.
+    ///   - preloadAll: For an animated image, whether or not all frames should be loaded before displaying.
+    ///                 Default is `false`.
+    ///   - onlyFirstFrame: For an animated image, whether or not only the first image should be
+    ///                     loaded as a static image. It is useful for preview purpose of an animated image.
+    ///                     Default is `false`.
+    public init(
+        scale: CGFloat = 1.0,
+        duration: TimeInterval = 0.0,
+        preloadAll: Bool = false,
+        onlyFirstFrame: Bool = false)
+    {
+        self.scale = scale
+        self.duration = duration
+        self.preloadAll = preloadAll
+        self.onlyFirstFrame = onlyFirstFrame
+    }
+}
+
+/// Represents the decoding for a GIF image. This class extracts frames from an `imageSource`, then
+/// hold the images for later use.
+public class GIFAnimatedImage {
+    let images: [KFCrossPlatformImage]
+    let duration: TimeInterval
+    
+    init?(from frameSource: ImageFrameSource, options: ImageCreatingOptions) {
+        let frameCount = frameSource.frameCount
+        var images = [KFCrossPlatformImage]()
+        var gifDuration = 0.0
+        
+        for i in 0 ..< frameCount {
+            guard let imageRef = frameSource.frame(at: i) else {
+                return nil
+            }
+            
+            if frameCount == 1 {
+                gifDuration = .infinity
+            } else {
+                // Get current animated GIF frame duration
+                gifDuration += frameSource.duration(at: i)
+            }
+            images.append(KingfisherWrapper.image(cgImage: imageRef, scale: options.scale, refImage: nil))
+            if options.onlyFirstFrame { break }
+        }
+        self.images = images
+        self.duration = gifDuration
+    }
+    
+    convenience init?(from imageSource: CGImageSource, for info: [String: Any], options: ImageCreatingOptions) {
+        let frameSource = CGImageFrameSource(data: nil, imageSource: imageSource, options: info)
+        self.init(from: frameSource, options: options)
+    }
+    
+    /// Calculates frame duration for a gif frame out of the kCGImagePropertyGIFDictionary dictionary.
+    public static func getFrameDuration(from gifInfo: [String: Any]?) -> TimeInterval {
+        let defaultFrameDuration = 0.1
+        guard let gifInfo = gifInfo else { return defaultFrameDuration }
+        
+        let unclampedDelayTime = gifInfo[kCGImagePropertyGIFUnclampedDelayTime as String] as? NSNumber
+        let delayTime = gifInfo[kCGImagePropertyGIFDelayTime as String] as? NSNumber
+        let duration = unclampedDelayTime ?? delayTime
+        
+        guard let frameDuration = duration else { return defaultFrameDuration }
+        return frameDuration.doubleValue > 0.011 ? frameDuration.doubleValue : defaultFrameDuration
+    }
+
+    /// Calculates frame duration at a specific index for a gif from an `imageSource`.
+    public static func getFrameDuration(from imageSource: CGImageSource, at index: Int) -> TimeInterval {
+        guard let properties = CGImageSourceCopyPropertiesAtIndex(imageSource, index, nil)
+            as? [String: Any] else { return 0.0 }
+
+        let gifInfo = properties[kCGImagePropertyGIFDictionary as String] as? [String: Any]
+        return getFrameDuration(from: gifInfo)
+    }
+}
+
+/// Represents a frame source for animated image
+public protocol ImageFrameSource {
+    /// Source data associated with this frame source.
+    var data: Data? { get }
+    
+    /// Count of total frames in this frame source.
+    var frameCount: Int { get }
+    
+    /// Retrieves the frame at a specific index. The result image is expected to be
+    /// no larger than `maxSize`. If the index is invalid, implementors should return `nil`.
+    func frame(at index: Int, maxSize: CGSize?) -> CGImage?
+    
+    /// Retrieves the duration at a specific index. If the index is invalid, implementors should return `0.0`.
+    func duration(at index: Int) -> TimeInterval
+}
+
+public extension ImageFrameSource {
+    /// Retrieves the frame at a specific index. If the index is invalid, implementors should return `nil`.
+    func frame(at index: Int) -> CGImage? {
+        return frame(at: index, maxSize: nil)
+    }
+}
+
+struct CGImageFrameSource: ImageFrameSource {
+    let data: Data?
+    let imageSource: CGImageSource
+    let options: [String: Any]?
+    
+    var frameCount: Int {
+        return CGImageSourceGetCount(imageSource)
+    }
+
+    func frame(at index: Int, maxSize: CGSize?) -> CGImage? {
+        var options = self.options as? [CFString: Any]
+        if let maxSize = maxSize, maxSize != .zero {
+            options = (options ?? [:]).merging([
+                kCGImageSourceCreateThumbnailFromImageIfAbsent: true,
+                kCGImageSourceCreateThumbnailWithTransform: true,
+                kCGImageSourceShouldCacheImmediately: true,
+                kCGImageSourceThumbnailMaxPixelSize: max(maxSize.width, maxSize.height)
+            ], uniquingKeysWith: { $1 })
+        }
+        return CGImageSourceCreateImageAtIndex(imageSource, index, options as CFDictionary?)
+    }
+
+    func duration(at index: Int) -> TimeInterval {
+        return GIFAnimatedImage.getFrameDuration(from: imageSource, at: index)
+    }
+}
+