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From: Carsten Dominik <carsten.dominik@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-orgmode@gnu.org
Subject: Re: Enriched/Org is a colorful Org
Date: Fri, 12 Apr 2013 09:13:47 +0200	[thread overview]
Message-ID: <5A8E6625-33C1-4B94-A78E-B08268C57A5F@gmail.com> (raw)
In-Reply-To: <83ip3s9rp8.fsf@gnu.org>


On 12 apr. 2013, at 08:41, Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Carsten Dominik <carsten.dominik@gmail.com>
>> Date: Fri, 12 Apr 2013 00:49:32 +0200
>> Cc: "emacs-orgmode@gnu.org List" <emacs-orgmode@gnu.org>
>> 
>>> Overlays should be OK as long as they aren't too many, and as long as
>>> you don't move them around too much, particularly in post-command-hook
>>> or some such.
>> 
>> This explanation sounds to me as if the display engine is building
>> some kind of tree of overlays to find properties changes quickly.  Too bad I don't have time to understand this stuff in more detail, it sounds interesting.
> 
> Just search xdisp.c for "overlay", you will see the story quite
> clearly, I think.

My Sunday pleasure reading project.

> 
> There are actually 2 aspects that make display engine's job harder
> with overlays.  One is indeed that finding overlays that "cover" a
> given buffer position is not a very efficient operation.  The display
> engine tries to overcome this to some extent by "centering" the
> overlay data base around the place in the buffer it is rendering.
> This is done for every screen line that is being examined by the
> display code.
> 
> The other problem is that there's no easy way of finding out which
> parts of the buffer are being affected by changes in overlays.  The
> consequence of this is that redisplay cannot easily determine whether
> a given portion of what's on the glass needs to be redrawn when
> overlays change.  The analysis of which part(s) of a window need to be
> redrawn is at the heart of redisplay optimizations, whereby Emacs
> tries very hard to reuse the portions of display that are already up
> to date.  Changes in overlays defeat that.  Therefore, changing _any_
> overlays in a buffer disables most, if not all, redisplay
> optimizations, meaning that the entire portion of the buffer that is
> displayed will be completely redrawn each time overlays _anywhere_ in
> the buffer are changed.

Wow.  OK.  I need to think to that, and I will try to take a
fresh look at overlay use in Org.

So the reason that the combination with hi-line is slow is because
hl-line is using post-command-hook to move its overlay, and redisplay
of a full window with org-mode is slow because so much stuff is
hidden and Emacs makes a full re-evaluation of what needs
to be displayed?

This makes sense.

Thanks for taking the time to get me this far.

- Carsten

  reply	other threads:[~2013-04-12  7:13 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-10  4:02 Enriched/Org is a colorful Org Jambunathan K
2013-04-10  9:54 ` Suvayu Ali
2013-04-10 10:16   ` Carsten Dominik
2013-04-10 10:39     ` Torsten Wagner
2013-04-10 10:48     ` Suvayu Ali
2013-04-10 10:53       ` Carsten Dominik
2013-04-10 11:20         ` Sebastien Vauban
2013-04-10 11:26           ` Carsten Dominik
2013-04-10 12:15           ` Jambunathan K
2013-04-10 11:57     ` Jambunathan K
2013-04-10 16:21     ` Eli Zaretskii
2013-04-10 16:43       ` Jambunathan K
2013-04-10 17:13         ` Eli Zaretskii
2013-04-10 19:58       ` Carsten Dominik
2013-04-10 20:16         ` Sebastien Vauban
2013-04-11  2:58           ` Carsten Dominik
2013-04-11 17:30             ` Eli Zaretskii
2013-04-11 22:49               ` Carsten Dominik
2013-04-12  6:41                 ` Eli Zaretskii
2013-04-12  7:13                   ` Carsten Dominik [this message]
2013-04-12  8:31                     ` Eli Zaretskii
2013-04-12 10:56                       ` Carsten Dominik
2013-04-12 11:49                         ` Torsten Wagner
2013-04-12 13:03                           ` Eli Zaretskii
2013-04-12 18:00                             ` Suvayu Ali
2013-04-12 18:38                               ` Eli Zaretskii
2013-04-13 10:50                                 ` Suvayu Ali
2013-04-12 12:36                         ` Eli Zaretskii
2013-04-13 12:24                           ` Sean O'Halpin
2013-04-13 14:38                             ` Jambunathan K
2013-04-13 15:01                             ` Eli Zaretskii
2013-04-12  8:35                     ` Bastien
2013-04-12 14:45                       ` François Pinard
2013-04-18 20:37                         ` Samuel Wales
2013-04-11 17:27         ` Eli Zaretskii
2013-04-11 22:46           ` Carsten Dominik
2013-04-10 12:12   ` Jambunathan K

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