Re: Support for callbacks...

[Lars Clausen <lrclause cs uiuc edu>]

On Wed, 16 Jul 2003, Herman Bruyninckx wrote:
> On Wed, 16 Jul 2003, Lars Clausen wrote:
>
> > On Tue, 15 Jul 2003, Herman Bruyninckx wrote:
> > > What is the status of callbacks in the Dia roadmap?
> > >
> > > I mean, is it (or will it be) possible to let some dia actions call a
> > > user-defined function?
> > >
> > > For example, a callback on each (dis)connection event on the canvas
> > > gives a lot of possibilities to add user-specific functionality to
> > > Dia. (E.g., to check whether it has a meaning in the users'
> > > application context to connect two given objects together.)
> >
> > That's funny, I was just thinking about that in the shower this morning.
> > A callback function would allow both elements and connectors to decide
> > whether they will allow the connection, and if they do, make any changes
> > that are needed.
> >
> > Unless, by 'user-defined function', you mean that the user can add a bit
> > of scripting to an object to be evaluated upon connection.  Given the
> > above, that could be added using the Python plugin, or any other plugin
> > that anyone cares to add.
>
> Indeed! That's exactly what I was looking for: a small extension of
> the Dia code could make tremendous changes in what a user can do with
> the program. My hope was to embed Dia as a "graphical editor" inside a
> robot simulation program... Most of the work would happen outside of
> Dia (via a Python plugin).

Dia doesn't currently support being embedded, though some of the work on
that has already been done from an earlier attempt (whose result I don't
know).  If you want to make Dia embeddable again, it'd be a great
improvement, and allow Dia to be used in a number of new places (browser
embedding, anyone?).

Have you looked at DiaCanvas(2)?  It does a number of the basic Dia things
(connections and handles), but is designed to be used as a widget.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| HÃrdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
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