From: Eli Zaretskii <eliz@gnu.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: esq@lawlist.com, 17678@debbugs.gnu.org
Subject: bug#17678: 24.4.50; Feature Request -- calculate new `window-start` & `window-end` before visual redisplay
Date: Wed, 11 Jun 2014 21:45:31 +0300 [thread overview]
Message-ID: <831tuvz3n8.fsf@gnu.org> (raw)
In-Reply-To: <jwv38fbe3ls.fsf-monnier+emacsbugs@gnu.org>
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Wed, 11 Jun 2014 14:00:39 -0400
> Cc: 17678@debbugs.gnu.org
>
> > I believe that the solution may be to have a `sneak-preview-redisplay`
> > whereby the *new* `window-start` and *new* `window-end` could be
> > correctly calculated without the visual buffer actually
> > being redisplayed.
>
> Of course, there's a circularity problem, here: if you need window-start
> (you can already compute window-end without an actual redisplay) in
> order to then install things like text-properties properties and
> overlays that affect the display, then those added properties may end up
> requiring changing window-start again (because they end up pushing point
> outside of the window and require a scroll).
Indeed. But if there's a hook that is forbidden from making such
changes to buffer text, then this is doable. Otherwise, it's a waste
of time having such a hook, since it will be unreliable.
> IIUC your particular use case (drawing crosshairs to show where the
> cursor is located) is one where what you really need is to know when
> window-start changes (just like follow-mode).
>
> So, a good feature might be one that runs a hook when redisplay decides
> that window-start needs to be reset (i.e. that point moved out of the
> window and we need to scroll).
The display engine changes window-start for several reasons, only one
of them being that point moved off screen.
I think follow-mode also needs to know when the window-end changes
(which could happen with no changes in window-start). This is
normally known only at the end of window redisplay, IIRC.
next prev parent reply other threads:[~2014-06-11 18:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-03 17:48 bug#17678: 24.4.50; Feature Request -- calculate new `window-start` & `window-end` before visual redisplay Keith David Bershatsky
2014-06-11 18:00 ` Stefan Monnier
2014-06-11 18:45 ` Eli Zaretskii [this message]
2014-06-11 21:58 ` Stefan Monnier
2014-06-12 17:54 ` Eli Zaretskii
2014-06-13 2:11 ` Stefan Monnier
2014-06-13 6:22 ` Eli Zaretskii
2014-06-13 12:34 ` Stefan Monnier
2014-06-13 13:27 ` Eli Zaretskii
2014-06-13 14:14 ` Stefan Monnier
2014-06-13 14:47 ` Eli Zaretskii
2014-06-13 18:47 ` Stefan Monnier
2014-06-13 20:21 ` Keith David Bershatsky
2014-06-13 20:59 ` Eli Zaretskii
2014-06-14 9:45 ` Eli Zaretskii
2014-06-14 17:10 ` Keith David Bershatsky
2014-06-15 2:24 ` Stefan Monnier
2014-06-13 16:22 ` Keith David Bershatsky
2014-06-13 17:55 ` Eli Zaretskii
2014-06-13 18:24 ` Keith David Bershatsky
2014-06-13 20:54 ` Eli Zaretskii
2014-06-13 21:19 ` Keith David Bershatsky
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