[debbugs-tracker] bug#12811: closed (24.3.50; `scroll-up/down-aggressively' don't seem to work as expected)

[GNU bug Tracking System]

Your message dated Sun, 11 Nov 2012 18:19:13 +0200
with message-id <address@hidden>
and subject line Re: bug#12811: 24.3.50; `scroll-up/down-aggressively' don't 
seem to work as expected
has caused the debbugs.gnu.org bug report #12811,
regarding 24.3.50; `scroll-up/down-aggressively' don't seem to work as expected
to be marked as done.

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-- 
12811: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12811
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--- Begin Message --- Subject: 24.3.50; `scroll-up/down-aggressively' don't seem to work as expected Date: Tue, 6 Nov 2012 00:27:55 +0100

Maybe I'm missing something, but after reading (info "(emacs) Auto
Scrolling") and the docstrings of the variables
`scroll-up/down-aggressively', the behavior I observe after playing a
bit doesn't seem right to me.

Recipe from "emacs -Q":
1. Visit the attached file.
2. Adjust the height of the Emacs GUI frame so that only lines 1 to 11
are visible.  With this setup it is easy to tell the relative position
of a line in the window in terms of percentage from the top or bottom,
since each line counts as 10% for such percentages.
3. Go to line 1.
4. Type: C-u 1 5 C-n
--> Point goes to line 16, and that line is centered in the window. So
everything is as expected so far.
5. M-: (setq scroll-up-aggressively 0.7) <RET>
6. Repeat steps #3 and #4.
--> This time I observe that point goes to line 16, but that line is
near the bottom of the window (9th line; 20% from the bottom) when it
should be near the top (4th line; 70% from the bottom).


I also observe a misbehavior when testing scroll-down-aggressively:
1. M-: (setq scroll-down-aggressively 0.7) <RET>
2. Go to line 30 and make that line the last visible one.
3. Type: C-u 1 1 C-p
--> I observe that point goes to line 19, but that line is the 10th in
the window (90% from the top), when it should be the 8th line (70%
from the top).


In GNU Emacs 24.3.50.1 (i386-mingw-nt6.1.7601)
 of 2012-11-05 on MS-W7-DANI
Bzr revision: 110809 address@hidden
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -I../../libs/libXpm-3.5.10/include -I../../libs/libXpm-3.5.10/src
 -I../../libs/libpng-1.2.37-lib/include -I../../libs/zlib-1.2.5
 -I../../libs/giflib-4.1.4-1-lib/include
 -I../../libs/jpeg-6b-4-lib/include
 -I../../libs/tiff-3.8.2-1-lib/include
 -I../../libs/libxml2-2.7.8-w32-bin/include/libxml2
 -I../../libs/gnutls-3.0.9-w32-bin/include
 -I../../libs/libiconv-1.9.2-1-lib/include'

Important settings:
  value of $LANG: ESN
  locale-coding-system: cp1252
  default enable-multibyte-characters: t


-- 
Dani Moncayo

test.txt
Description: Text document

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#12811: 24.3.50;	`scroll-up/down-aggressively' don't seem to work as expected
>
>
>
>
> Date: 
>
> Sun, 11 Nov 2012 18:19:13 +0200
>
>
>
>
> > Date: Sun, 11 Nov 2012 14:33:33 +0100
> > From: Dani Moncayo <address@hidden>
> > Cc: address@hidden
> > 
> > The second test (related to `scroll-down-aggressively') produces a
> > better result (point shown at line 9 - 80% from the top) but not the
> > expected one (line 8 - 70% from the top).
>
> Emacs doesn't count in lines, it counts in pixels.  And since a line
> has a finite size, where exactly those 70% end is not well determined
> (is it the top of the line, the bottom of the line, somewhere in
> between?).
>
> > In any case, since the result is almost the right one, and more
> > importantly, since I've discovered that these two variables are not
> > worth the trouble, I'm ok with closing this bug report now.
>
> Thanks, closing.
>
>
> --- End Message ---