commit 25221506bd280a018659c7931e42acccf742ab59
Author: Reda Lemeden <reda@thoughtbot.com>
Date:   Sat Sep 6 16:12:09 2014 +0200

    Initial commit

diff --git a/ImageSourceHelpers.swift b/ImageSourceHelpers.swift
new file mode 100644
index 0000000..3311a27
--- /dev/null
+++ b/ImageSourceHelpers.swift
@@ -0,0 +1,34 @@
+import UIKit
+import ImageIO
+import MobileCoreServices
+
+func CGImageSourceContainsAnimatedGIF(imageSource: CGImageSource) -> Bool {
+  let isTypeGIF = UTTypeConformsTo(CGImageSourceGetType(imageSource), kUTTypeGIF)
+  let imageCount = CGImageSourceGetCount(imageSource)
+  return isTypeGIF != 0 && imageCount > 1
+}
+
+func CGImageSourceGIFFrameDuration(imageSource: CGImageSource, index: Int) -> NSTimeInterval {
+  let containsAnimatedGIF = CGImageSourceContainsAnimatedGIF(imageSource)
+  if !containsAnimatedGIF { return 0.0 }
+
+  var duration = 0.0
+  let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, UInt(index), nil) as NSDictionary
+  let GIFProperties: NSDictionary? = imageProperties[kCGImagePropertyGIFDictionary] as? NSDictionary
+
+  if let properties = GIFProperties {
+    duration = properties[kCGImagePropertyGIFUnclampedDelayTime] as Double
+
+    if duration <= 0 {
+      duration = properties[kCGImagePropertyGIFDelayTime] as Double
+    }
+  }
+
+  let threshold = 0.02 - Double(FLT_EPSILON)
+
+  if duration > 0 && duration < threshold {
+    duration = 0.1
+  }
+
+  return duration
+}
diff --git a/Matsuri.swift b/Matsuri.swift
new file mode 100644
index 0000000..0fd2dae
--- /dev/null
+++ b/Matsuri.swift
@@ -0,0 +1,149 @@
+import UIKit
+import ImageIO
+
+class AnimatedImage: UIImage {
+  // MARK: - Constants
+  let framesToPreload = 10
+  let maxTimeStep = 1.0
+
+  // MARK: - Public Properties
+  var delegate: UIImageView?
+  var frameDurations = [NSTimeInterval]()
+  var frames = [UIImage?]()
+  var totalDuration: NSTimeInterval = 0.0
+
+  // MARK: - Private Properties
+  private lazy var displayLink: CADisplayLink = CADisplayLink(target: self, selector: "updateCurrentFrame")
+  private lazy var preloadFrameQueue: dispatch_queue_t = dispatch_queue_create("co.kaishin.GIFPreloadImages", DISPATCH_QUEUE_SERIAL)
+  private var currentFrameIndex = 0
+  private var imageSource: CGImageSource?
+  private var timeSinceLastFrameChange: NSTimeInterval = 0.0
+
+  // MARK: - Computed Properties
+  var currentFrame: UIImage? {
+    return frameAtIndex(currentFrameIndex)
+  }
+
+  private var isAnimated: Bool {
+    return imageSource != nil
+  }
+
+  // MARK: - Initializers
+  required init(coder aDecoder: NSCoder) {
+    super.init(coder: aDecoder)
+  }
+
+  required init(data: NSData, delegate: UIImageView?) {
+    let imageSource = CGImageSourceCreateWithData(data, nil)
+    self.delegate = delegate
+
+    if CGImageSourceContainsAnimatedGIF(imageSource) {
+      super.init()
+      attachDisplayLink()
+      prepareFrames(imageSource)
+      startAnimating()
+    } else {
+      super.init(data: data)
+      stopAnimating()
+    }
+  }
+
+  // MARK: - Factories
+  class func imageWithName(name: String, delegate: UIImageView?) -> Self? {
+    let path = NSBundle.mainBundle().bundlePath.stringByAppendingPathComponent(name)
+    let data = NSData.dataWithContentsOfFile(path, options: nil, error: nil)
+    return (data != nil) ? imageWithData(data, delegate: delegate) : nil
+  }
+
+  class func imageWithData(data: NSData, delegate: UIImageView?) -> Self? {
+    return self(data: data, delegate: delegate)
+  }
+
+  // MARK: - Display Link Helpers
+  func attachDisplayLink() {
+    displayLink.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
+  }
+
+  // MARK: - Frame Methods
+  private func prepareFrames(source: CGImageSource!) {
+    imageSource = source
+
+    let numberOfFrames = CGImageSourceGetCount(self.imageSource)
+    frameDurations.reserveCapacity(Int(numberOfFrames))
+    frames.reserveCapacity(Int(numberOfFrames))
+
+    for index in 0..<Int(numberOfFrames) {
+      let frameDuration = CGImageSourceGIFFrameDuration(source, index)
+      frameDurations.append(frameDuration)
+      totalDuration += frameDuration
+
+      if index < framesToPreload {
+        let frameImageRef = CGImageSourceCreateImageAtIndex(self.imageSource, UInt(index), nil)
+        let frame = UIImage(CGImage: frameImageRef, scale: 0.0, orientation: UIImageOrientation.Up)
+        frames.append(frame)
+      } else {
+        frames.append(nil)
+      }
+    }
+  }
+
+  func frameAtIndex(index: Int) -> UIImage? {
+    if Int(index) >= self.frames.count { return nil }
+
+    var image: UIImage? = self.frames[Int(index)]
+
+    updatePreloadedFramesAtIndex(index)
+
+    return image
+  }
+
+  private func updatePreloadedFramesAtIndex(index: Int) {
+    if frames.count <= framesToPreload { return }
+
+    if index != 0 {
+      frames[index] = nil
+    }
+
+    for internalIndex in (index + 1)...(index + framesToPreload) {
+      let adjustedIndex = internalIndex % frames.count
+
+      if frames[adjustedIndex] == nil {
+        dispatch_async(preloadFrameQueue) {
+          let frameImageRef = CGImageSourceCreateImageAtIndex(self.imageSource, UInt(adjustedIndex), nil)
+          self.frames[adjustedIndex] = UIImage(CGImage: frameImageRef)
+        }
+      }
+    }
+  }
+
+  func updateCurrentFrame() {
+    if !isAnimated { return }
+
+    timeSinceLastFrameChange += min(maxTimeStep, displayLink.duration)
+    var frameDuration = frameDurations[currentFrameIndex]
+
+    while timeSinceLastFrameChange >= frameDuration {
+      timeSinceLastFrameChange -= frameDuration
+      currentFrameIndex++
+
+      if currentFrameIndex >= frames.count {
+        currentFrameIndex = 0
+      }
+
+      delegate?.layer.setNeedsDisplay()
+    }
+  }
+
+  // MARK: - Animation
+  func stopAnimating() {
+    displayLink.paused = true
+  }
+
+  func startAnimating() {
+    displayLink.paused = false
+  }
+
+  func isAnimating() -> Bool {
+    return !displayLink.paused
+  }
+}
\ No newline at end of file
diff --git a/UIImageView+Matsuri.swift b/UIImageView+Matsuri.swift
new file mode 100644
index 0000000..9b49a6a
--- /dev/null
+++ b/UIImageView+Matsuri.swift
@@ -0,0 +1,51 @@
+import UIKit
+
+extension UIImageView {
+  // MARK: - Computed Properties
+  var animatableImage: AnimatedImage? {
+    if image is AnimatedImage {
+      return image as? AnimatedImage
+    } else {
+      return nil
+    }
+  }
+
+  var isAnimating: Bool {
+    return animatableImage?.isAnimating() ?? false
+  }
+
+  var animatable: Bool {
+    return animatableImage != nil
+  }
+
+  // MARK: - Method Overrides
+  override public func displayLayer(layer: CALayer!) {
+    if let image = animatableImage {
+      if let frame = image.currentFrame {
+        layer.contents = frame.CGImage
+      }
+    }
+  }
+
+  // MARK: - Setter Functions
+  func setAnimatedImage(named name: String) {
+    image = AnimatedImage.imageWithName(name, delegate: self)
+  }
+
+  func setAnimatedImage(#data: NSData) {
+    image = AnimatedImage.imageWithData(data, delegate: self)
+  }
+
+  // MARK: - Animation
+  func startAnimating() {
+    if animatable {
+      animatableImage!.startAnimating()
+    }
+  }
+
+  func stopAnimating() {
+    if animatable {
+      animatableImage!.stopAnimating()
+    }
+  }
+}