From: Eli Zaretskii <eliz@gnu.org>
To: Steven Allen <steven@stebalien.com>
Cc: 72323@debbugs.gnu.org, storm@cua.dk
Subject: bug#72323: 31.0.50; line-move unconditionally resets vscroll to 0
Date: Sat, 27 Jul 2024 21:11:21 +0300 [thread overview]
Message-ID: <86ikwq1z92.fsf@gnu.org> (raw)
In-Reply-To: <87zfq2hg4n.fsf@stebalien.com> (bug-gnu-emacs@gnu.org)
> Cc: "Kim F. Storm" <storm@cua.dk>
> Date: Sat, 27 Jul 2024 10:57:44 -0700
> From: Steven Allen via "Bug reports for GNU Emacs,
> the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>
> Fixing home/end (beginning of line, end of line) case seems trivial:
> don't call `line-move' in these cases (or have `line-move' short-circuit
> when `arg' is 0). However, even after reading all the comments about
> scrolling images, I'm still not sure why it's necessary to reset vscroll
> to 0.
Because otherwise what line-move does cannot be described in sensible
terms. If vscroll is not reset, then what would be the reference for
such a "line move"? By its very definition, line-move moves N screen
lines wrt the line which was its starting point, but with vscroll
non-zero that starting point could be anywhere.
In addition, when we move to another screen line, the value of vscroll
cannot be meaningfully kept, because its meaning is tightly coupled to
the screen line where it was applied. In essence, vscroll is a trick
to allow display of a tall display element (image, text using a large
fonts, etc.) in a window whose height is too small to show all of the
display element at once.
> After commenting this line out, I can't tell a difference, even
> when scrolling images with and without `auto-window-vscroll' and
> `try-vscroll'.
line-move is not just for scrolling across images, it is also about
scrolling across tall text lines and other display elements. In any
case, asking for removal of that reset is a non-starter, for the
reasons explained above, so it isn't going to happen. The solution
for any Lisp program that doesn't want vscroll to be rest is not to
call line-move.
> I was hoping Kim could shed some light on this.
I'd be thrilled to hear from Kim, but I'm as guilty of the code in
line-move as he is, so "blame" me if you want.
next prev parent reply other threads:[~2024-07-27 18:11 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-27 17:57 bug#72323: 31.0.50; line-move unconditionally resets vscroll to 0 Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-27 18:11 ` Eli Zaretskii [this message]
2024-07-27 20:10 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-28 4:50 ` Eli Zaretskii
2024-07-28 20:07 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-28 20:10 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-29 11:14 ` Eli Zaretskii
2024-07-29 11:12 ` Eli Zaretskii
2024-07-29 14:30 ` Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-18 17:42 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-18 17:38 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-18 18:21 ` Eli Zaretskii
2024-08-18 18:40 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-18 19:01 ` Eli Zaretskii
2024-08-18 22:17 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-19 11:06 ` Eli Zaretskii
2024-08-19 17:30 ` Steven Allen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-09-30 0:51 ` Stefan Kangas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=86ikwq1z92.fsf@gnu.org \
--to=eliz@gnu.org \
--cc=72323@debbugs.gnu.org \
--cc=steven@stebalien.com \
--cc=storm@cua.dk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.