Re: [gtkmm] Gdk::Colormap and Gdk::Color

[MHL Schulze t-online de (Martin Schulze)]

Hi Michael!

Ah, the problem is now getting clearer for me. I missed the point because
I missed a line in my code that does the allocation for me (using rgb 
values):
col.rgb_find_color(gc->get_colormap());

I see that your code will work as long as you can use the same colormap,
that being the case when:
"the depth of the colormap's visual (...) match(es) the depth of the
drawable for which the GC was created" (gdk doc for gdk_gc_set_colormap).

However I don't see where your code makes life any easier or more 
convinient.
If it's a performance issue then you should find out whether gdk colormaps
already buffer the colors for you or eat time every time you call alloc.
(You will have to look in the gdk sources - I don't find anything in the 
docs.)

Regards,

  Martin


Am 08.08.2002 12:15 schrieb(en) Michael Koziarski:
> > > {
> > > Glib::RefPtr<Gdk::Pixmap> pm = Gdk::Pixmap::create(x,y,d);
> > > Glib::RefPrt<Gdk::GC> gc = Gdk::GC::create(gc);
> > > Glib::RefPtr<Gdk::Colormap> cm = gc->get_colorap()
> > > Gdk::Color red("red");
> > >
> > > cm->alloc_color(red);
> > > pm->draw_line(gc, 0, 0, 100, 100);
> > > }
> >
> > I've never used colormaps but from what I see I think that the
> following
> > solution should do the same:
>
> Thanks for the reply,  It seems we were both halfway there.  you set
> the foreground, but in order for it to actually be used (i.e. line be
> red rather than black), it's gotta be alloc'd too.
>
> So my question about Color's being Copy friendly still stands,  as
> does my question about 'automagic-color' widgets.
>
> Basically what I'm thinking is pretty much this (allowing for typos &
> missing #includes)
>
> http://www.koziarski.org/GColorManager.C
> http://www.koziarski.org/GColorManager.h
>
> Any problems with that code?  or am I needlessly duplicating work
> available elsewhere?
>
>
>
> --
> ========================================================================
> | Michael Koziarski                   |"Conventional wisdom is often   |
> | Data Engineer, Linux user           | long on convention and short   |
> | & Objectivist.                      | on wisdom" --                  |
> | http://www.koziarski.com            | Warren E. Buffett, BRK.A       |
> ========================================================================
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