GNU bug report logs - #873
Annoying recentering when scrolling down

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: "Juanma Barranquero" <lekktu <at> gmail.com>
To: "Emacs Bug Tracker" <submit <at> debbugs.gnu.org>
Subject: Annoying recentering when scrolling down
Date: Wed, 3 Sep 2008 18:15:14 +0200

Package: emacs
Version: 23.0.60
Severity: normal

After setting this in .emacs:

(setq scroll-preserve-screen-position 'always
      scroll-conservatively           most-positive-fixnum ;; any large number
      scroll-step                     0)

scroll-down causes recentering. This is a regression.

The bug was apparently introduced by the following change:

2008-08-06  Chong Yidong  <address <at> hidden>

        * xdisp.c (try_scrolling): Use iterator to find the scroll margin,
        instead of window-end which does the wrong thing at eob.
        (try_cursor_movement): Minor optimization.
        (redisplay_window): If scroll margin is defined, don't assume
        window doesn't need scrolling.


emacs-devel discussion:

http://lists.gnu.org/archive/html/emacs-devel/2008-08/msg00903.html

Message #10 received at 873 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Chong Yidong <cyd <at> stupidchicken.com>
To: emacs-devel <at> gnu.org
Cc: 873 <at> debbugs.gnu.org, "Juanma Barranquero" <lekktu <at> gmail.com>
Subject: Recentering on scroll
Date: Sat, 25 Oct 2008 14:03:50 -0400

Can anyone reproduce bug#873 (occasional recentering during C-n)?  I
thought I could reproduce it at some point, using the recipe given in
that bug report, but I can't seem to do it now.

> After setting this in .emacs:
>
> (setq scroll-preserve-screen-position 'always
>       scroll-conservatively           most-positive-fixnum ;; any large number
>       scroll-step                     0)
>
> scroll-down causes recentering. This is a regression.

Message #15 received at 873 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: "Juanma Barranquero" <lekktu <at> gmail.com>
To: "Chong Yidong" <cyd <at> stupidchicken.com>
Cc: emacs-devel <at> gnu.org, 873 <at> debbugs.gnu.org
Subject: Re: Recentering on scroll
Date: Mon, 27 Oct 2008 01:57:13 +0100

On Sat, Oct 25, 2008 at 19:03, Chong Yidong <cyd <at> stupidchicken.com> wrote:

> Can anyone reproduce bug#873 (occasional recentering during C-n)?  I

I can still reproduce it on Windows, though the effect's frequency
varies with frame size and font (it seems to happen more often with
DejaVu Sans Mono than Courier New, for example).

  Juanma

Message #20 received at 873-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Chong Yidong <cyd <at> stupidchicken.com>
To: "Juanma Barranquero" <lekktu <at> gmail.com>
Cc: emacs-devel <at> gnu.org, 873-done <at> debbugs.gnu.org
Subject: Re: Recentering on scroll
Date: Mon, 27 Oct 2008 01:19:00 -0400

"Juanma Barranquero" <lekktu <at> gmail.com> writes:

> On Sat, Oct 25, 2008 at 19:03, Chong Yidong <cyd <at> stupidchicken.com> wrote:
>
>> Can anyone reproduce bug#873 (occasional recentering during C-n)?  I
>
> I can still reproduce it on Windows, though the effect's frequency
> varies with frame size and font (it seems to happen more often with
> DejaVu Sans Mono than Courier New, for example).

I managed to reproduce it, and found the bug that (I think) was causing
this problem.  I've checked in a fix.

Message #27 received at 873 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: "Juanma Barranquero" <lekktu <at> gmail.com>
To: "Chong Yidong" <cyd <at> stupidchicken.com>
Cc: emacs-devel <at> gnu.org, 873 <at> debbugs.gnu.org
Subject: Re: Recentering on scroll
Date: Tue, 28 Oct 2008 13:40:07 +0100

On Mon, Oct 27, 2008 at 06:33, Chong Yidong <cyd <at> stupidchicken.com> wrote:

> Actually, the fix caused a few problems; I've reverted it for now, and
> will check in a new version in a couple of hours.

With your most recent patch the unwanted recentering does not happen. Thanks.

Line-by-line scroll is quite jumpy, though, as compared to next-line
in Emacs 22.X, or even to previous-line in the current trunk.

  Juanma

Message #32 received at 873-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: "Juanma Barranquero" <lekktu <at> gmail.com>
To: 873-done <at> debbugs.gnu.org
Date: Thu, 20 Nov 2008 10:25:03 +0100

Fixed by Chong Yidong with this change:


2008-10-27  Chong Yidong  <cyd <at> stupidchicken.com>

        * xdisp.c (try_scrolling): When computing the distance from the
        scroll margin to PT, try moving some distance past the window
        bottom before giving up.


http://cvs.savannah.gnu.org/viewvc/emacs/emacs/src/xdisp.c?r1=1.1268&r2=1.1269&pathrev=MAIN

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