Re: Themes on GnuStep?

[Robert E. Hartley]

Sorry I took a while to answer, but I am back from the course I was teaching
in Colorado. (Nice people, beautiful scenery)

Adam Fedor wrote:

> "Robert E. Hartley" wrote:
> >
> > If it ws possible to make use of Gtk+ type themes on GnuStep, it would
> > make it easier to have a more homgeneous appearance between the apps,
> > and in theory a PDA sized version of GnuStep could be created that would
> > have the appropriate parts carefully "#ifdef"'ed out of the way, both to
> > avoid theme'ed versions of the code (for those that consider sort of
> > thing offensive), or conversely, to enable a smaller, theme'd only
> > version.
> >
>
> You might want to look at the discuss-gnustep mail archives for a
> discussion of this.

Thank you,  I will do that.  I should have done that first.


> Theoretically themes should work well in GNUstep
> with very few design changes. I'd really like to see a well though-out
> design for this - as I don't know much about themes myself, I can't
> really comment more than that.

Once I have the latest snapshot building nicely from source, I will go in and
see what I have to do to get it working the way I did with Motif.  In the
meantime, I will will whip up a summary of how it works in Motif, and how
I imagine it might work in GnuStep.


> I'd really avoid #ifdefs.

Me too.  The reason I mentioned it is because many of the users of Motif do
not need or want themes, so we had to have a way so that the Motif sources
with the themeing code would build to the exact same binary with the themeing
capability switched off at the source level.


> There should be a way to use userDefaults to
> specify a theme, and have the code dynamically loaded in at runtime.

Actually, that is how we do it for Motif.  We can also specify which shared
library to use for the rendering engine in this file. At the moment, I have a
pixmap rendering engine but a theme file could be built that would invoke an
OpenGL or OpenInventor type renderer once it is written.  (I had this weird
idea about making an OpenGL based theme that looked like the regular Motif,
but once you started touching things, it got squishy and stretched when the
mouse was used on it before snapping back.  Kind of like a sidewalk chewing
gum theme.... it was just an idea that _could_ have been done, rather easily,
if I had the time.)



> The
> speed hit in deciding between drawing with themes and without should be
> trivial - ideally we would always use a theme, it's just that most of
> the time it would be the 'standard' one.

I totally agree with you.

I am wondering of it might actually make the source code smaller and more
portable if GnuStep was using an external theme engine.  We could probably
reduce the number of Xlib drawing calls to a bare minimum, perhaps even
abstrating it to the point where we could have a library that just invokes
function calls to the native graphics API, be it X11, MicroWindows, PicoGUI,
or even Quartz and OpenGL (maybe using Glut)

The way I foresee it, we should be able to make use of whatever theme is in
use by Gtk, Qt (or Motif).  If we are compatible with say Gtk theme files,
then there will never be a shortage of theme files and pixmaps to choose
from.

Anyways, I will continue along this line once I have had some time to catch
up on what I missed in the last few days,

thanks for your encouragement,

Robert


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