Re: Goocanvas issues

["Paul Davis" <pjdavis engineering uiowa edu>]

On 5/21/07, Murray Cumming <murrayc murrayc com> wrote:
> On Sun, 2007-05-20 at 18:05 -0500, Paul Davis wrote:
> > >
> > > In itemsimple.hg, I have this:
> > > _WRAP_PROPERTY("fill-pattern",Cairo::RefPtr<Cairo::Pattern>)
> > >
> > > I'm attempting to use it like such:
> > > Cairo::RefPtr<Cairo::Pattern> create_pattern() { ... }
> > > item->property_fill_pattern() = create_pattern() ;
> > >
> > > But its generating this error:
> > > (lt-demo:27094): GLib-GObject-WARNING **: unable to set property
> > > `fill-pattern' of type `GooCairoPattern' from value of type
> > > `glibmm__CustomBoxed_N5Cairo6RefPtrINS_7PatternEEE'
> > >
> > > I've posted a message on the goocanvas list asking about the
> > GooCairo*
> > > types. I've also been looking through the properties in Gtkmm that
> > use
> > > RefPtr's and I can't find anywhwere that they do something special
> > to
> > > account for the refptr being passed in. (Like making a call to
> > > Glib::unwrap or what not).
> > >
> > > Anyone have an idea?
> > >
> > > Thanks,
> > > Paul Davis
> > >
> >
> > Quick follow up, this piece of code actually works:
> >
> > Cairo::RefPtr<Cairo::Pattern> p =
> > _create_stipple( "mediumseagreen" ) ;
> > g_object_set( rect->gobj(), "fill-pattern", p->cobj(), NULL ) ;
> >
> > So the property is fine taking the Cairo pattern which leads me to
> > believe that there's a problem in how that property is getting
> > wrapped.
>
> This is probably the first time that Cairo::RefPtr has been used in
> properties. I think we need a Property* or Value* template
> specialization, as we already have for Glib::RefPtr.
>
> That should probably go in gtkmm, but you can try putting it somewhere
> common in libgoocanvasmm for now. Tell me if you don't manage that - I
> can try when I have a chance in the next few days.

I've tried and failed to figure out this template specialization.
Specifically, I'm running into problems that appear to be caused
because Cairo doesn't seem to use the gobject system. In fact,
grepping for gtk in the cairo source tree only reveals one occurence
in a comment.

Damon mentioned on the GooCanvas mailing list that this is the reason
that he included the GooCairoPattern type and registered
GooCairoPattern as a GType.

So, on this front, I'm stumped for now.

Paul Davis

> --
> Murray Cumming
> murrayc murrayc com
> www.murrayc.com
> www.openismus.com