Simple GIF file reader/writer library (gifwrap) and example application (gifbox). C++/Cinder/Visual Studio 2013.

1. Download Cinder 0.9.0 for Visual Studio 2013:
   https://libcinder.org/static/releases/cinder_0.9.0_vc2013.zip
   (The app code contains some Windows-only pieces right now; the library should be Windows-free, although I haven't verified that.)

2. Add an environment variable named CINDER_090_2013 that points to the extracted Cinder folder.

3. And of course, pull and compile this app.

There are many great GIF libraries available. The motivation for attempting my own was primarily pure curiosity about the format, although in looking through various implementations I didn't come across anything that really hit my sweet spot: A couple of image format-independent classes I could drop into a project that had a minimal API for providing my own translation from whatever local bitmap storage class I happen to be using, and pluggable components for the "soft" algorithms.

So this repo is really two things, an isolated library with a few classes for reading and writing GIF files, as well as a simple viewer application to verify that everything's working.

The code is in three main pieces:

• Everything in sdk/gifwrap/ is the main portable GIF library. It's intended that the sdk/gifwrap/src/gifwrap/ folder can be dropped in a project to add GIF support. One thing worth noting is that it was written with Visual Studio 2013, and while there shouldn't be anything specific to Visual Studio, you will need at least C++11 compliance.
• Everything in the sdk/kt/ folder has been pulled from a generic library for application development I've written.
• Everything in the main src/ folder is app-specific for the test GIF viewer application.

The compiled app is extremely simple. On startup it loads an included sample GIF. If you want to view another GIF, drag and drop onto the app window. There is a single control to change the playback speed. Also, the GIF is automatically scaled to the current window size, so the aspect ratio will be off.

The latest Windows binary release can be downloaded here:
https://github.com/hackborn/gif_viewer/releases/download/v0.1.0/gif_viewer.zip

There are two things to do if you're using the lib in your own code:

1. Create a class that provides storage for and translation to the local bitmap format. In this app, the reading class is cinder_fig/texture_gif_list and the writing class is cinder_gif/path_writer. The list class specializes gif::List to the local bitmap format by supplying a std::function in the constructor that receives GIF bitmaps and answers local bitmaps. The writer class specializes gif::WriterT to translate file paths into the GIF bitmap format. Both classes are used in the src/app/app class.

2. Create an instance of gif::File and call load() on a file and the gif::List subclasses mentioned above. When load() is finished you'll have a list populated with drawable bitmaps.

There are some features of the GIF format that I haven't seen in the wild, so they aren't currently supported. If I can find examples that have any of these items I'll add support:

• (reading) Comment blocks
• (reading) Text blocks
• (reading) Interlacing
• (reading) Transparency
• (writing) Writing support is experimental right now, and at the very least I know it's doing a terrible job of color matching.

There is no license on this code -- do whatever you like -- but I have no responsibility for any errors or damage that results from using it. It's worth noting that the LZW decompression code is based on the very nice code in the Go framework. I'm not sure what impact rewriting it has, but you might want to follow the Go (BSD, I believe) license if you have any concerns.

Questions or comments, contact me:
Eric Hackborn
hackborn@gmail.com