From: Le Wang <l26wang@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 12401@debbugs.gnu.org
Subject: bug#12401: scroll-preserve-screen-position broken with font height faces
Date: Mon, 10 Sep 2012 20:37:06 +0800 [thread overview]
Message-ID: <CAM=K+ioEoP3+cz2N_pV3K+82jKpjcPmS5y+mDii0GFS6sBLN5w@mail.gmail.com> (raw)
In-Reply-To: <83mx0yl4s2.fsf@gnu.org>
Thanks for the quick response, Eli.
On Mon, Sep 10, 2012 at 3:23 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> scroll-preserve-screen-position tries to preserve the
> _screen_position_ of point, i.e. where you find the cursor, after it
> executes one of the scrolling commands. But since arbitrary pixel
> coordinates on the screen might in general (in the presence of
> variable-size fonts) correspond to one of 2 possible text lines, Emacs
> needs to choose where to put the cursor. What exactly do you expect
> Emacs to do in such a situation, where it simply _cannot_ keep the
> same pixel coordinates?
I understand the problem.
> IOW, what is the "contract" that you expect Emacs to keep under
> scroll-preserve-screen-position? Is it just that doing N C-v's
> followed by N M-v's brings point to the same location where it was
> before this sequence of 2N commands? Or do you also expect something
> from each individual C-v/M-v, and if so, what exactly?
The contract should be C-v followed by M-v should bring the point back
to the same line. If the max_column after C-v is less than
current_column, then either restoring the column as current_column or
max_column is acceptable.
Although the current behaviour of C-p followed by C-n seems to restore
current_column, so that would be more consistent.
As a corrolary, if this contract is enforced then N C-v followed by N
M-v should also bring point back to the same line.
>> For reference this package works just fine with variable height faces:
>> http://www.cs.utah.edu/~eeide/emacs/scroll-in-place.el.gz
>
> I cannot use it, neither in Emacs 24.2 nor in the current trunk code:
> it complains about a missing function screen-width. Please provide a
> complete recipe for using this package, starting with "emacs -Q", in
> Emacs 24.2 or newer, so I could study what it does and how.
Sorry about this. It seems the version I use comes from XEmacs and
I've made a small fix. I've placed it here:
https://gist.github.com/3690403
> For that matter, please also provide all the details collected by
> report-emacs-bug, they might be important.
The repro steps I've described starts from "emacs -Q". I can still
provide this information, if needed though.
--
Le
next prev parent reply other threads:[~2012-09-10 12:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-10 6:12 bug#12401: scroll-preserve-screen-position broken with font height faces Le Wang
2012-09-10 7:23 ` Eli Zaretskii
2012-09-10 12:37 ` Le Wang [this message]
2012-09-10 18:02 ` Eli Zaretskii
2012-09-10 13:26 ` Stefan Monnier
2012-09-10 18:05 ` Eli Zaretskii
2012-09-10 20:42 ` Stefan Monnier
2012-09-12 8:08 ` martin rudalics
2012-09-12 16:48 ` Eli Zaretskii
2012-09-12 17:38 ` martin rudalics
2022-02-09 9:17 ` Lars Ingebrigtsen
2022-03-09 16:22 ` Lars Ingebrigtsen
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