Re: Emacs and Gnome Canvas

[Eli Zaretskii]

> Date: Thu, 15 Jul 2010 10:48:12 +0200
> From: Jan Djärv <address@hidden>
> CC: address@hidden, address@hidden
> 
> >> The changes that require redisplay would have to notify the Canvas that 
> >> things
> >> changed.  I think this style is more efficient.
> >
> > What do you mean by "changes that require redisplay"?  Suppose a
> > character was inserted or deleted -- would that need to notify the
> > Canvas?
> 
> Yes.

But the inserted character could be in the portion that is not
displayed at all, in which case it does not "require redisplay".  Who
should decide whether redisplay is necessary?  If that's Emacs, then
it should know a lot about the display layout.  If its the Canvas,
then it should know a lot about what portions of the buffer text are
on the screen.

Besides, this mean a thorough redesign of Emacs objects.  Currently,
they are totally unaware of the display engine, and don't request any
redisplays.  They just modify themselves and that's it.

> >  How about an arbitrary mouse move?
> 
> If it resulted in a different highlightning of a link, yes.

Again, how to know that?  Note that some mouse movements perform
complex operations on Emacs objects, like popping up windows and
frames.