Re: Preparing for Cairo?

[ben carlyle invensys com]

Hrrm...





Todd Fisher <toddf simosoftware com>
Sent by: gtk-list-bounces gnome org
04/11/2004 10:23 AM

 
        To:     "David Necas (Yeti)" <yeti physics muni cz>
        cc:     gtk-list gnome org
        Subject:        Re: Preparing for Cairo?


>    Perhaps, this document will help 
> http://people.redhat.com/otaylor/guadec5/

Hrmm.. not really. I've read pretty much all the information I could find 
on cairo and it's integration with gtk, but much of it is in tanalising 
snippets. This one covert quite a lot, but is pitched at a low level. 
While it talks about gtk/cairo integration in terms of how an expose event 
occurs (which is also what is wrapped up in GtkCairo) it makes only subtle 
hints at GnomeCanvas becoming (or being replaced by) a GtkCanvas. This 
could imply that no API change for the canvas is expected over this 
transition. If so, I haven't found any definitate statement to that 
effect, and I would like to solicit one :)

This September/2003 post from Owen @ 
http://mail.gnome.org/archives/gtk-devel-list/2003-September/msg00027.html 
hints more strongly that a common rendering model could give GnomeCanvas a 
nudge down to the gtk level. On the other hand, to my mind it doesn't rule 
out the possibility of an API rewrite to take advantage of the new Cairo 
capabilities.

This August/2004 post on the cairo lists @ 
http://cairographics.org/pipermail/cairo/2004-August/001775.html indicates 
that no cairo canvas existed at that time, although 
http://lists.gnu.org/archive/html/criawips-devel/2004-07/msg00005.html 
announces work starting on such a project (I haven't been able to track 
down the actual software). Either way, what I would like is a gtk canvas 
(possibly built on cairo) rather than a cairo canvas that won't integrate 
with gtk widgets. Fundamentally I need to be able to draw, zoom, and pan 
shapes while allowing gtk buttons and other widgets to live and be scaled 
alongside my lines and curves.

If I start working with GnomeCanvas today, how much headwind will I hit 
once the gtk/cairo integration actually goes ahead? Will GnomeCanvas 
evolve into a cairo-based canvas or be replaced by it? Will its api have 
to change in order to support the "you beaut" cairo features that are 
coming along?

Is there are a better alternative to using a canvas at this point for the 
kind of work I'm looking into?

> also these links might help:
> http://cairo.freedesktop.org/
> and
> http://cairo.freedesktop.org/bin/view/cairo/GtkCairo
> hope, these help :-)

Thanks for your effort, Todd. Perhaps I should try to engage Owen or a 
gnome-canvas developer more directly.

> David Necas (Yeti) wrote:
> >On Wed, Nov 03, 2004 at 02:52:32PM +1000, ben carlyle invensys com 
wrote:
> >>So, what to do? Is there any canvas object currently in existence that 

> >>will fill the role I have for it (and preferrably be reintegrated into 

> >>gtk) over the next 6-12 months? Which API should I code to, and what 
steps 
> >>can I take to minimse rework if such a beast does not exist?
> >I don't know the answer, sorry, but I'm interested in it too
> >(I'll have to redesign some b0rken graph widgets sometime
> >next year and I'd like to base them on The Right Thing, if
> >possible).