Allegro 4: Giftware
Allegro is a free and open source software library for video game development.   
The functionality of the library includes support for basic 2D graphics, image manipulation, text output, audio output, midi music, input and timers, as well as additional routines for fixed-point and floating-point matrix arithmetic, unicode strings, file system access, file manipulation, data files, and (limited, software-only) 3D graphics.
As of version 4.0, programs that use the library work on DOS, Microsoft Windows, BeOS, Mac OS X, and various Unix-like systems with (or without) X Window System, abstracting their application programming interfaces (APIs) into one portable interface. There is also an independent port of Allegro on AmigaOS 4.
The library is written in the C programming language and designed to be used with C or C++. It comes with extensive documentation and many examples.
The community of Allegro users have contributed several library extensions to handle things like scrolling tile maps and import and export of various file formats (e.g. PNG, GIF, JPEG images, MPEG video, Ogg, MP3, IT, S3M, XM music, TTF fonts, and more). There are also bindings for several programming languages available, such as Python, Perl, Scheme, C#, D and others.
Allegro can be used in conjunction with OpenGL by using the library AllegroGL which extends Allegro's functionality into OpenGL and therefore the hardware.
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