Re: Backend Documentation

[Fred Kiefer]

Manuel Teira schrieb:
> I'm interested into GNUstep on embedded devices (ARM based ones). The first
> thing I would like to work on would be a directfb backend for gnustep,
> mainly to avoid the need of an xserver on a constrained device.
> Googling a bit, it seems that some attempts to achieve this very same thing
> were made time ago, but checking out gnustep code it seems that there's no
> such backend contributed.
> It would be nice if someone could direct me to documentation about what a
> backend should implement, or some already existing efforts (either complete
> or incomplete) to provide such a directfb backend to gnustep.

The simplest solution here is surely to start of with the cairo backend
for the drawing code. As far as I remember there are cairo surfaces for
directfb, that way you could reuse the whole drawing code while writing
just one simple class (FBCairoSurface).

The harder bit is the display server, that part that manages windows and
events. This has to be a subclass of GSDisplayServer and implement at
least all the methods with subclassResponsibility: in them, plus the
filling of the event queue. If you know what you are doing none of this
is to hard. I remember writing most of the windows backend on one
weekend and that was including drawing.

The final part is to wire all this together and make it configurable at
build time. I am sure you will get support from the mailing list for that.

One final note: There is already a fork of GNUstep aimed at ARM devices,
mySTEP (http://www.quantum-step.com/wiki.php?page=mySTEP). This doesn't
use directfb, so it isn't what you are looking for. You may be
interested in the tool chain of that project, though.

Hope this helps
Fred