GNU libxmi is a C/C++ function library for rasterizing 2-D vector graphics. It can draw 2-D graphical primitives, including wide polygonal lines and circular and elliptical arcs, into a user-supplied matrix of pixels. Sophisticated line styles, such as multicolored dashing patterns, can be specified. There is also support for filling and texturing polygons. It can be used as a drop-in rendering module in any application that needs to scan-convert 2-D vector graphics. It is highly customizable. For example, the `pixel' datatype can be redefined at compile time. The algorithm used for compositing pixels can be redefined too. By default, libxmi uses the Painter's Algorithm (a new pixel value replaces an old one). But it would be trivial to install it so that it uses alpha compositing instead. The package, and its header file xmi.h, include full documentation.