Gifu/source/Gifu.swift

152 lines
4.1 KiB
Swift

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_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)
pauseAnimation()
} else {
super.init(data: data)
}
}
// MARK: - Factories
class func imageWithName(name: String, delegate: UIImageView?) -> Self? {
let path = NSBundle.mainBundle().bundlePath.stringByAppendingPathComponent(name)
if let data = NSData(contentsOfFile: path) {
return imageWithData(data, delegate: delegate)
}
return 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 = Int(CGImageSourceGetCount(self.imageSource))
frameDurations.reserveCapacity(numberOfFrames)
frames.reserveCapacity(numberOfFrames)
for index in 0..<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 pauseAnimation() {
displayLink.paused = true
}
func resumeAnimation() {
displayLink.paused = false
}
func isAnimating() -> Bool {
return !displayLink.paused
}
}