keefo / giraffe

Encode animated GIF files on the iPhone

Giraffe

Giraffe is a legacy name for a GIF encoder that I wrote long ago. Now, the GIF encoding library used in this project is ANGif, a much better, more advanced GIF encoder. The soul purpose of this repository is to provide an example of how one might use ANGif in an iOS project.

Someone with the intention of using ANGif in their project should have a look at both the UIImagePixelSource.m and ExportViewController.m files. These are what use ANGif in conjunction with ANImageBitmapRep to export GIF images on the iPhone. ANGif itself does not require ANImageBitmapRep to work, but my example does require it.

ANGif Example

Just to give a sense of the easy-to-use ANGif library, here is an example of what encoding an animated GIF could look like:

ANGifEncoder * encoder = [[ANGifEncoder alloc] initWithOutputFile:@"myFile.gif" size:CGSizeMake(100, 100) globalColorTable:nil];
[encoder addApplicationExtension:[[ANGifNetscapeAppExtension alloc] init]];
[encoder addImageFrame:anImageFrame];
[encoder addImageFrame:anotherImageFrame];
[encoder closeFile];

The addImageFrame: method takes an instance of ANGifImageFrame, which can be created in several different ways. In order to provide a UIImage to work with ANGif, a class must be made that implements the ANGifImageFramePixelSource protocol. In Giraffe, the UIImagePixelSource class is a simple UIImage wrapper that implements this protocol. The ANGifImageFrame object is also what includes the delay time (a.k.a. frame rate).

License

Copyright (c) 2011 Alex Nichol
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
   derived from this software without specific prior written permission.

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