Re: Emacs and Gnome Canvas

[Jan Djärv]

YAMAMOTO Mitsuharu skrev 2010-07-17 11.25:
> > > > > > On Sat, 17 Jul 2010 11:18:56 +0200, Jan Djärv<address@hidden>  said:
>
> > > > > The whole area, or divide the updated area to some collection of
> > > > > rectangles?  The former is too inefficient for small updates.
> > >
> > > > No it is not, this is how Gtk+ operates all the time, even for
> > > > small updates.
> > >
> > > Isn't GTK+ using the model I've been saying, i.e., drawing only in
> > > respose to exposure, especially when using cairo?
>
> > Gtk+ (or rather Gdk) makes a syntetic expose event.  But if you have
> > a small change, it will do it just for that small change, the same
> > it does for big changes.
>
> Sorry, I don't understand.  Does GTK+ or GDK do double-buffering for
> drawings outside the handler of (possibly synthetic) expose events?

No, not outside expose events.  But if I insert a character in a text edit 
widget, it invalidates itself. That generates a syntetic expose event.  When 
the event is processed, Gdk arranges for all drawings to go to the backing 
store.  When the event is fully processed, the backing store is copied to the 
window.

Copying the whole window or just a portion should hardly matter w.r.t. 
performance.  This is all done in the X server.

        Jan D.