Re: Can we make set_point_both less expensive?

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: martin rudalics <address@hidden>, address@hidden, address@hidden
> Date: Fri, 20 Mar 2015 17:53:22 -0400
> 
> > discussed.  Stefan wants redisplay to move point also in the case
> > where some Lisp moved point and entered a region of buffer positions
> > that has a certain text property.
> 
> Yes and no: I want pre-redisplay-function to do that.

This will only work if pre-redisplay-function is called in a way that
guarantees it will catch the position of point after the previous
command.  Another, related, requirement is that we never call
pre-redisplay-function when point is in a position that is not
supposed to be visible by the user.

Overall, it sounds like a non-trivial deviation from the original
purpose of pre-redisplay-function, as I understand it.

> Whether you consider it as "redisplay" or not is another question,

I don't consider pre-redisplay-function part of redisplay.  Martin was
clearly talking about redisplay, so I answered in kind.

What I _am_ saying is that only redisplay, in its last part, knows
where the cursor will be positioned.

> but when I say "redisplay" in this thread I mean the C part that
> fills & uses the glyph matrices

That part of redisplay doesn't yet know where the cursor will be.
Cursor positioning happens after that.