Re: [gnomemm] Creating a custom Gnome::Canvas::Item

[Michael Babcock <mbabcock la creatureshop henson com>]

Murray Cumming wrote:
> On Wed, 2002-07-17 at 19:54, Michael Babcock wrote:
>
> > Hmmm. I'm not familiar with the internals of how gtkmm wraps gtk (or I 
> > try not to be), so tokens like GNOME_CANVAS_ITEM, g_object_new, and 
> > get_type don't mean much to me ;)
>
>
> They aren't meant to, though they would to a GTK+ coder. Just trust me
> on this one. If it works then we'll make it easier.
>  
>
> > I looked at line.{h,cc}g but it is also wrapping an existing C type. In 
> > the above what does get_type() return, the C equivalent of a 
> > Canvas::Item type or of a Canvas::Line type?
>
>
> The most-derived wrapped type - Canvas::Item if you inherit from that.
>
>
> > Do I have to create a new C 
> > type?
>
>
> Hopefully not. Try it and see. If you do need to then we already have a
> system for that too.
>  
>
> > I was hoping to be able to derive a new C++ Canvas::Item type and have 
> > the library handle the conversion issues between the C++ and the Glib 
> > object systems, like gtkmm does so that we can derive a new Gtk::Widget.
>
>
> Like I said, I don't know how this is done in C, or whether it's
> something that makes sense. If you just try it then we will know
> something from your results.
>
>
> > I guess I have to use the property system in order to get the canvas to 
> > properly update my new item when I change it, right?
>
>
> Possibly. I don't know much about CanvasItems. Maybe they use properties
> in the same way as Gtk::CellRenderers. I've never investigated them.
>
>
> > Am I suppose to use 
> > the ConstructParams constructor for this?
>
>
> Almost certainly not.

Okay, I'll work on it some more and get back to you. Thanks for the 
quick response.

--
Michael Babcock
Jim Henson's Creature Shop