Hi, this is a small note for people wondering (like I was, a few days ago) how the hell can I animate my GIFs in an IKImageView !? Well, unlike the NSImageView, where you only have to set a property to YES to animate you GIFs, with the IKImageView, it’s a bit more complicated. You have to subclass your IKImageView, and set an overlay layer on the image, setting it yourself. In my image viewer application, the name of my subclass of IKImageView is ImageView (original isn’t it ? :p) So here is the code of ImageView handling the animation of GIFs, with comments :
#import "ImageView.h" @implementation ImageView -(void)awakeFromNib { // create an overlay for the image (which is used to play animated gifs) // EDIT: well, don't do that here, due to some initialization orders // problem, it might gives an error and not create the overlay // I leave that line here for the records ^^ //[self setOverlay:[CALayer layer] forType:IKOverlayTypeImage]; // NOTE: calling this before anything else seems to fix a lot of // problems ... maybe it's initializing a few things internally // on the first call ... [super setImageWithURL:nil]; } -(BOOL)isGIF:(NSString *)path { // checks if the path points to a GIF image NSString * pathExtension = [[path pathExtension] lowercaseString]; return [pathExtension isEqualToString:@"gif"]; } -(void)setImageWithURL:(NSURL *)url { // EDIT: this is where we create the overlay now, but only if it doesn't // already exists. // checks if a layer is already set if ([self overlayForType:IKOverlayTypeImage] == nil) [self setOverlay:[CALayer layer] forType:IKOverlayTypeImage]; // remove the overlay animation [[self overlayForType:IKOverlayTypeImage] removeAllAnimations]; // check if it's a gif if ([self isGIF:[url path]] == YES) { // loads the image NSImage * image = [[NSImage alloc] initWithContentsOfFile:[url path]]; // get the image representations, and iterate through them NSArray * reps = [image representations]; for (NSImageRep * rep in reps) { // find the bitmap representation if ([rep isKindOfClass:[NSBitmapImageRep class]] == YES) { // get the bitmap representation NSBitmapImageRep * bitmapRep = (NSBitmapImageRep *)rep; // get the number of frames. If it's 0, it's not an animated gif, do nothing int numFrame = [[bitmapRep valueForProperty:NSImageFrameCount] intValue]; if (numFrame == 0) break; // create a value array which will contains the frames of the animation NSMutableArray * values = [NSMutableArray array]; // loop through the frames (animationDuration is the duration of the whole animation) float animationDuration = 0.0f; for (int i = 0; i < numFrame; ++i) { // set the current frame [bitmapRep setProperty:NSImageCurrentFrame withValue:[NSNumber numberWithInt:i]]; // this part is optional. For some reasons, the NSImage class often loads a GIF with // frame times of 0, so the GIF plays extremely fast. So, we check the frame duration, and if it's // less than a threshold value, we set it to a default value of 1/20 second. if ([[bitmapRep valueForProperty:NSImageCurrentFrameDuration] floatValue] < 0.000001f) [bitmapRep setProperty:NSImageCurrentFrameDuration withValue:[NSNumber numberWithFloat:1.0f / 20.0f]]; // add the CGImageRef to this frame to the value array [values addObject:(id)[bitmapRep CGImage]]; // update the duration of the animation animationDuration += [[bitmapRep valueForProperty:NSImageCurrentFrameDuration] floatValue]; } // create and setup the animation (this is pretty straightforward) CAKeyframeAnimation * animation = [CAKeyframeAnimation animationWithKeyPath:@"contents"]; [animation setValues:values]; [animation setCalculationMode:@"discrete"]; [animation setDuration:animationDuration]; [animation setRepeatCount:HUGE_VAL]; // add the animation to the layer [[self overlayForType:IKOverlayTypeImage] addAnimation:animation forKey:@"contents"]; // stops at the first valid representation break; } } // release the image [image release]; } // calls the super setImageWithURL method to handle standard images [super setImageWithURL:url]; } @end
So, what I do here is that I create an overlay layer to display the image, and when I find an animated GIF, I load it using the NSImage class, and then I scan it to extract all the frames and setup the layer animation. So to display an animated GIF, you now only have to use the setImageWithURL method of your ImageView class. The advantage of using IKImageView over NSImageView, is that it can be resized while still playing your animation smoothly, and it benefit of all the features of the IKImageView class.
