Important note: this project is reactivated since september 2013. It was re-forked from LibreDWG.
This is a library to allow reading data from a DWG file. That's a very important acquisiton, which may improve a lot the ability of the free software comunity to develop more features in the field of computer technical drawing (CAD).
The DWG structure is very complicated, it seems to be crafted so that none can easily understand it. That's a strong reason to not use it, and that's also why we do not provide the writing feature in the library. One should use LibDWG mainly to read such files, filtering them to some other format, free and usable.
At the initial moment (April 2009), there seemed to be no other project like this, it's uniqueness came from the used programming language (C) and also from the ugly situation of the CAD program market, with a disgusting configuration of (almost?) monopoly.
The last version (0.6) is able to read DWG file formats R13, R14, R2000 and R2004.
It provides a small utility called "dwg-dump" to extract information from DWG files, in a human readable form. And also other, named "dwg-dxf", to convert to DXF R2000 (useful to use with LibreCad).
Extended data is not read, because they depends on third party applications to be interpreted, so they are completely useless in a free software environment. Then, objects XDATA are simply by-passed when scanning the data.
Here we have a simple and quick overview about other formats, more suitable for free CAD applications.
DXF (The evil! Don't count so much on it.)
DGN (Only v7? Not enough.)
BRL-CAD: worth to explore.
After that list, it's easy to figure out the intention to create something like a filter, which takes a DWG file and transform it to one (or several) of the open alternatives (whenever there be one :-). It is a long way to reach this goal. And also, other people are working on this, for example: VectorSection
Other interesting ability of such filter would be to create image files like PNG, SVG, EPS and even PDF, for example.