From: martin rudalics <rudalics@gmx.at>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 12600@debbugs.gnu.org
Subject: bug#12600: 24.2.50; linum-mode: line numbers in fringe do not refresh when resizing frame
Date: Fri, 12 Oct 2012 11:35:57 +0200 [thread overview]
Message-ID: <5077E47D.4080300@gmx.at> (raw)
In-Reply-To: <837gqw843w.fsf@gnu.org>
> Quite a few struct members related to the
> display engine (and I suppose other core structures as well) are
> insufficiently, in accurately, or even downright incorrectly
> documented. I try to fix every such problem I bump into, FWIW.
If these concern the display engine exclusively, there's no problem.
Problems arise when the window handling code is supposed to change them.
>> For example, what does the "displayed buffer's text modification events
>> counter as of last time display completed" mean?
>
> This one sounds quite clear, please tell which part needs further
> clarifications. It would be better to say "counter of the displayed
> buffer's modification events as of last time display completed", but
> somehow I'm guessing it's not what you had in mind.
That's exactly what I had in mind: Either something that corresponds
textually to what is used in buffer.h or just mention the name of the
corresponding field used in buffer.h. As it stands currently, I have to
either guess what is meant or go through the comparisons in the code to
find out.
>> Suppose redisplay has set this to 37. Apparently, setting it to 36
>> means that the next redisplay will notice that for this window
>> display is not accurate and has to be redone because 36 < 37.
>
> Not necessarily. It depends on what is recorded in the buffer's
> BUF_MODIFF slot.
IIUC this can only increase monotonously (modulo wraparounds, but in
that case ...).
>> But why is a flag insufficient to accomplish that? IIUC it's set only
>> once by mark_window_display_accurate_1 and everywhere else reset to 0.
>> Why can't we set it to "accurate" in mark_window_display_accurate_1 and
>> "inaccurate" everwhere else?
>
> How would this work when the displayed buffer is modified behind
> redisplay's back? The last_modified slot belongs to the window, which
> redisplay controls, but it doesn't control the buffer, which could
> well be displayed in other windows as well and modified through there.
> The display engine treats each window separately; when it displays
> some window, it doesn't use information from other windows.
When last_modifed_flag is set, the window must be redisplayed. Now if
someone else (including the display engine) decremented last_modified,
things were different indeed. But as it stands I don't see any such
assignment. OTOH when the buffer iself is modified it has to be
redisplayed anyway because we hardly know where the change happened. So
I don't see why such a comparison of counters is useful. But maybe I'm
missing something.
>> And why do we have additional fields for last_overlay_modified and
>> window_end_valid? What sense does it make to handle these separately?
>
> Because changes in overlays do not constitute changes in buffer
> contents, and are done via yet another set of primitives, yet they do
> require redisplay. Also because each one of these can allow and
> disallow certain distinct redisplay optimizations, at least in
> principle.
I doubt whether such optimizations exist. Suppose we could exclude a
change to happen within the bounds of a window as for example a buffer
displayed with a window starting at M and ending at N and an overlay
modified at some position < M or > N. Wouldn't this require to
associate each single overlay with a modification counter?
> As for window_end_valid flag, it's there to allow yet another set of
> redisplay optimizations.
I think that a correct implementation would have for each window w
(w->last_modified < MODIFF) => (NOT (w->window_end_valid))
but strongly doubt that this implication holds currently.
>> For example, wherever last_modified is reset to 0 last_overlay_modified
>> is always reset to 0 too. Isn't that plain overkill?
>
> The potential for separate optimizations is not realized, that's true.
> But it exists; I'm not sure we should remove it, and I surely won't
> spend any of my personal time trying. Fixing real bugs in the display
> engine is enough to fill my free time already. Of course, if you feel
> like it, and if no one objects, feel free to make these cleanups.
I don't intend to make any cleanups. I'd like to have a simple routine
we can use to reset any such structur members within window.c and have
that DTRT. Currently, `window-end' is clearly broken and we should fix
it.
martin
next prev parent reply other threads:[~2012-10-12 9:35 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-07 23:03 bug#12600: 24.2.50; linum-mode: line numbers in fringe do not refresh when resizing frame Christoph Scholtes
2012-10-08 7:31 ` Eli Zaretskii
2012-10-08 9:17 ` martin rudalics
2012-10-08 13:59 ` Stefan Monnier
2012-10-08 15:48 ` Eli Zaretskii
2012-10-09 9:36 ` martin rudalics
2012-10-09 17:04 ` Eli Zaretskii
2012-10-10 10:22 ` martin rudalics
2012-10-10 15:45 ` Eli Zaretskii
2012-10-11 7:12 ` martin rudalics
2012-10-11 16:56 ` Eli Zaretskii
2012-10-12 7:32 ` martin rudalics
2012-10-12 8:52 ` Eli Zaretskii
2012-10-12 9:35 ` martin rudalics [this message]
2012-10-12 13:51 ` Eli Zaretskii
2012-10-12 15:42 ` martin rudalics
2012-10-12 14:55 ` Stefan Monnier
2012-10-12 15:36 ` Eli Zaretskii
2012-10-12 15:43 ` martin rudalics
2012-10-13 8:56 ` Eli Zaretskii
2012-10-13 9:51 ` martin rudalics
2012-10-13 12:45 ` Eli Zaretskii
2012-10-13 17:45 ` martin rudalics
2012-10-13 18:08 ` Eli Zaretskii
2012-10-14 10:21 ` martin rudalics
2012-10-14 12:06 ` Eli Zaretskii
2012-10-14 18:33 ` martin rudalics
2012-10-14 20:01 ` Eli Zaretskii
2012-10-15 9:41 ` martin rudalics
2012-10-15 19:39 ` Eli Zaretskii
2012-10-16 9:39 ` martin rudalics
2012-10-16 17:35 ` Eli Zaretskii
2012-10-15 9:40 ` martin rudalics
2012-11-09 9:49 ` martin rudalics
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=5077E47D.4080300@gmx.at \
--to=rudalics@gmx.at \
--cc=12600@debbugs.gnu.org \
--cc=eliz@gnu.org \
/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.