What does the gd graphics plugin (based on libgd) do?
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Author:  sleske [ 17 Sep 2015, 23:41 ]
Post subject:  What does the gd graphics plugin (based on libgd) do?

Apart from the commonly used graphics plugins such as "android" and "gtk_drawing_area", Navit also has a graphics plugin called gd, based on the GD Graphics library (libgd).

I recently noted that this driver has not had any real work done since 2010 - currently it does not even build without some tricks.
Looking at the source code ( navit/graphics/gd/graphics_gd.c ) I noticed that the plugin does not even appear to draw to a window; instead it produces image files, or (if I understand correctly) sends image data through a socket or via shared memory (using the API from <sys/shmkey.h>).

Now I am wondering: What is this plugin supposed to be good for? It seems to communicate with some other software via sockets or shared memory, but there is nothing like that in the Navit sources. Is there some external project for that?

I also searched trac and the Navit wiki without success.

Unless we can find out what the plugin is meant for, I will probably delete it - maintaining code is pretty pointless if you do not even know what it is good for...

Author:  KaZeR [ 19 Sep 2015, 05:02 ]
Post subject:  Re: What does the gd graphics plugin (based on libgd) do?

The only usage i can remember of was embedding in a webpage.

At some point in the past, you were able to try navit live from a webpage. It was really cool :)
The server side code was never published, but I don't remember why. Probably it was a request for a company paying for it.

It would be great if you could share the fixes, as i would actually love to see this feature back!

Author:  sleske [ 19 Sep 2015, 20:54 ]
Post subject:  Re: What does the gd graphics plugin (based on libgd) do?

Thanks for the information.

I haven't done any real work on the gd graphics; I just fiddled a bit with CMake to make it build (by adding "-lgd" to the library parameters).

The feature you describe does sound cool, but if half the code is missing, I see no point in keeping the other half. Plus, while embedding Navit in a webpage is cool, I don't think it makes a lot of sense.

There are plenty of web maps available (, Bing, the one with the multi-coloured G...), and they do a great job. Navit's main feature (to me) is that it runs on many devices, and off-line - I think we should work on that, instead of turning it into a web server.

So unless some other information shows up, I'll probably delete the code shortly. Of course, if someone wants to work on it later, it will be available - that's the nice thing about version control :-).

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