> -----Original Message-----
> From: James Henstridge [mailto:[EMAIL PROTECTED]]
> Sent: maandag 17 april 2000 14:32
> To: Dia Mailing List
> Subject: New canvas??
>
>
> At GUADEC, me and Alex were discussing whether it would be a
> good idea to
> write a new canvas which dia and other programs could use.
> The idea was
> to come up with a canvas that has the good points of the Dia
> canvas (such
> as good handling of multiple views for the one canvas
> structure, abstract
> renderer allowing things like transparent printing support)
> and those of
> the GnomeCanvas (benefits from using the GtkObject system,
> using libart,
> etc).
>
> I don't know if The DiaCanvas package is a good starting
> point though, as
> it only seems to use GtkObjects fairly superficially. The signalling
> system could simplify a lot of the diagram <-> display
> notification that
> occurs in the current setup for instance. (one other comment about
> DiaCanvas - it should be GPL licenced, as it is based on GPL
> code. You
> can't relabel GPL code as LGPL).
I've asked to Alex about that, he said it won't be a problem to him.
> So do you think this is a good idea? I think such a project could be
> useful for a lot programs (there is a lot of code in the
> GNOME CVS tree
> handling multiple views of a canvas based display). Is there
> anyone who
> would be interested in helping out on a project like this?
DiaCanvas has it's weaknesses. I added some stuff like dynamic connection points
(which are created when a handle attaches to a line), but it increases the complexity
quite a bit... It can be removed of course. I don't know about anybody using that
feature (exept my example program ;-).
I'm currently starting to create a constraint based canvas based on GnomeCanvas and
Cassowary <http://www.cs.washington.edu/research/constraints/cassowary/index.html>
(which has been LGPL'ed since version 0.60.0). I'm currently making a GTK wrapper for
the C++ classes, but it takes some time still. Once I have that done it should be
fairly easy to apply constraints to objects making them, connect or behave according
to some rules.
I'm quite charmed by the way constraints can solve placement problems, but since I
never did anything using constraints (well, except programmatical constraints, which
are quite inflexible) I'm not sure where this will end.
DIA could also benefit from such a canvas, but I don't know when...
Regards,
Arjan
