LibDWG - free access to DWG
Important note: this project is inactive since july 2009. The most interesting project, forked from this one here, and which keeps going on with development, is LibreDWG. So, we are keeping this site only for history reasons.
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 interesting applications, 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.
Since 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.
You will also notice this interesting feature: we use Esperanto to code the library and the API documentation would be available only in this language. But this is another battle...
Features of the last version
Here are the objects the library can read:
LAYOUT
LAYER
LINE
LWPOLYLINE
CIRCLE
ELLIPSE
ARC
TEXT
MTEXT
RAY
POINT
BLOCK, SEQEND
ATTDEF
INSERT
ATTRIB
Limitations of the last version
Unfortunately, we have to show more limitations than features.
- Interface (API):
- The last version (0.3) is a demonstration for what we achieved. It's not very usable, missing a clear and simple interface to the data (though the intrinsic complexity in DWG).
- Version:
- The library can read only DWG files with version R15 (best known as R2000). This version is enough well documented by Open Design Alliance (ODA). With the specification provided by ODA, one poorly succeed to read versions R2004 and R2007, because there are missing some internal details.
- Writing:
- For you, who read until here, I may confess: the read-only limitation comes from the fact that we simply didn't succeed to create (write) a correct DWG file, which could be read by the AutoCAD application. There are some peaces of bytes we simply couldn't decipher.
Alternatives
Here we have a simple and quick overview about other formats, more suitable for free CAD applications.
For the future
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.
