From: Eli Zaretskii <eliz@gnu.org>
To: martin rudalics <rudalics@gmx.at>
Cc: 12170@debbugs.gnu.org, wbrodie@panix.com
Subject: bug#12170: save-excursion fails boundary case with recenter
Date: Fri, 10 Aug 2012 22:01:51 +0300 [thread overview]
Message-ID: <83393uefkw.fsf@gnu.org> (raw)
In-Reply-To: <50251EED.3010804@gmx.at>
> Date: Fri, 10 Aug 2012 16:47:09 +0200
> From: martin rudalics <rudalics@gmx.at>
> Cc: 12170@debbugs.gnu.org
>
> (defun f (n)
> (save-this-window-excursion (forward-line (- n)) (recenter 0)))
>
> (let ((buffer (switch-to-buffer "foo"))
> (height (1- (window-height (get-buffer-window "foo")))))
> (insert-char 10 (* height 2))
> (let ((pt (point)))
> (f height)
> (redisplay)
> (message "height %s old %s new %s" height pt (point)))))
>
> so I'd suspect the culprit somewhere in redisplay_window's code
By saying "culprit" you mean you think this is a bug? I think Stefan
explained why it isn't.
> if (w->optional_new_start
>
> w->optional_new_start is 1 from `recenter'
>
> && CHARPOS (startp) >= BEGV
> && CHARPOS (startp) <= ZV)
> {
> w->optional_new_start = 0;
> start_display (&it, w, startp);
> move_it_to (&it, PT, 0, it.last_visible_y, -1,
> MOVE_TO_POS | MOVE_TO_X | MOVE_TO_Y);
> if (IT_CHARPOS (it) == PT)
> w->force_start = 1;
> /* IT may overshoot PT if text at PT is invisible. */
> else if (IT_CHARPOS (it) > PT && CHARPOS (startp) <= PT)
> w->force_start = 1;
>
> w->force_start 1 will cause redisplay to honor the start position set up
> by `recenter'
Only if point will be visible when window is displayed starting at
startp.
> But I don't have the slightest idea how calling
>
> (set-window-start (selected-window) ,start t)
>
> would remedy this. Eli will soon teach us a lesson here.
Not sure there's a lesson here to learn, but set-window-start sets the
w->force_start flag unconditionally, so it will hold even if point is
not in the displayed portion of the window (i.e., point will move).
Does that explain things?
next prev parent reply other threads:[~2012-08-10 19:01 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-10 1:23 bug#12170: save-excursion fails boundary case with recenter Bill Brodie
2012-08-10 9:34 ` martin rudalics
2012-08-10 9:50 ` Bastien
2012-08-10 13:03 ` martin rudalics
2012-08-10 13:40 ` Bill Brodie
2012-08-10 14:47 ` martin rudalics
2012-08-10 16:18 ` Stefan Monnier
2012-08-10 16:47 ` martin rudalics
2012-08-10 17:07 ` Stefan Monnier
2012-08-10 19:01 ` Eli Zaretskii [this message]
2012-08-11 9:32 ` martin rudalics
2012-08-11 11:11 ` Eli Zaretskii
2012-08-11 14:22 ` martin rudalics
2012-08-11 15:10 ` Eli Zaretskii
2012-08-11 16:05 ` martin rudalics
2012-08-11 16:31 ` Eli Zaretskii
2012-08-11 16:49 ` Eli Zaretskii
2012-08-12 10:31 ` martin rudalics
2012-08-11 16:27 ` Bill Brodie
2012-08-10 15:04 ` Stefan Monnier
2012-08-10 15:46 ` Bill Brodie
2012-08-10 16:46 ` martin rudalics
2012-08-10 16:46 ` martin rudalics
2012-08-10 18:58 ` Eli Zaretskii
2012-08-11 9:31 ` martin rudalics
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