The ANTLR ANSI C and GCC source to source translation framework includes an ANSI-C parser which builds trees, a GCC parser which builds trees, a GCC tree parser (for you to subclass to do transformations), and a GCC tree emitter. The GCC parser is only for GCC's extensions to C, not C++. It is based on GCC 2.95.2.
Geist is an object-based image editor, designed to be used in conjunction with the GIMP. While the GIMP specializes in pixel editing, geist deals with objects. Geist's specialties are antialiased truetype fonts and a full RGBA colorspace with transparent objects blended quickly in realtime. Supported objects are lines, text (with wordwrapping and font styles), rectangles, images (zoomed or scaled with or without antialiasing), and polygons. Geist saves documents in XML, and can export to all image formats supported by imlib2.
Gifsicle is a powerful command-line program for manipulating GIF image files. It has good support for transparency and colormap manipulation, simple image transformations (cropping, flipping), and creating, deconstructing, and editing GIF animations. It can also optimize GIF animations for space. Also included is a GIF animation viewer and a program that checks whether two GIFs look the same.
GLE (Graphics Layout Engine) is a graphics scripting language designed for creating publication quality figures (e.g., a chart, plot, graph, or diagram). GLE supports various chart types (including function plot, histogram, bar chart, scatter plot, contour plot, color map, and surface plot) through a simple but flexible set of graphing commands. More complex output can be created by relying on GLE's scripting language, which is full featured with subroutines, variables, and logic control. GLE relies on LaTeX for text output and supports mathematical formulae in graphs and figures.