Re: Wrapper functions for setting up RGBA colormaps

["Matt Hoosier" <mwhoosier gmail com>]

Thanks, Murray.

On 6/15/06, Murray Cumming <murrayc murrayc com> wrote:
> On Wed, 2006-06-14 at 15:41 -0500, Matt Hoosier wrote:
> > I'd like to do some drawing using the alpha channel for blending. At
> > least one technique for doing this in raw Gtk+ is to query whether an
> > RGBA colormap exists:
> >
> >    GdkScreen* screen = gtk_widget_get_screen(widget);
> >
> >     GdkColormap* colormap = gdk_screen_get_rgba_colormap(screen);
> >     gboolean supports_alpha = TRUE;
> >
> >     if (!colormap)
> >     {
> >         /* display doesn't support compositing; fall back to RGB */
> >         colormap = gdk_screen_get_rgb_colormap(screen);
> >         supports_alpha = FALSE;
> >     }
> >
> >     gtk_widget_set_colormap(widget, colormap);
> >
> > One then can later inspect the 'supports_alpha' flag when setting up
> > the colormap on a Cairo context.
> >
> > Gtkmm doesn't seem to offer wrappers for this RGBA colormap
> > fetching/setting. Should I continue to use the underlying Gtk+ API, or
> > is there a cleaner way of doing this kind of thing in Gtkmm?
>
> I wrapped those functions in HEAD just a few days ago, so they are not
> available yet in stable releases:
> http://cvs.gnome.org/viewcvs/gtkmm/ChangeLog?r1=1.486&r2=1.487
>
> But it should be totally OK to use the C API together with the gtkmm
> API, using gobj().
>
> --
> Murray Cumming
> murrayc murrayc com
> www.murrayc.com
> www.openismus.com