From: "Jan D." <jan.h.d@swipnet.se>
To: Eli Zaretskii <eliz@gnu.org>
Cc: Dmitry Gutov <dgutov@yandex.ru>,
"16621@debbugs.gnu.org" <16621@debbugs.gnu.org>
Subject: bug#16621: 24.3.50; Periodic timer + overlays = flickering near point
Date: Tue, 4 Feb 2014 23:08:13 +0100 [thread overview]
Message-ID: <76F58FD5-23A5-43EC-91FA-BAD933BB41DA@swipnet.se> (raw)
In-Reply-To: <83a9e63m1n.fsf@gnu.org>
Hi.
4 feb 2014 kl. 17:00 skrev Eli Zaretskii <eliz@gnu.org>:
>> Date: Tue, 04 Feb 2014 08:17:38 +0200
>> From: Dmitry Gutov <dgutov@yandex.ru>
>> CC: 16621@debbugs.gnu.org, monnier@IRO.UMontreal.CA
>>
>>> You mean, outside Emacs? Yes, probably, but then this isn't an Emacs
>>> issue, and I know absolutely nothing about it.
>>
>> Would a windowing system know which Emacs display states are
>> "consistent", and which aren't?
>
> If hints are needed, we could do that.
>
>> AFAIU, flickering happens when the screen refreshes while Emacs display
>> is in an inconsistent state. Like, you've cleared a rectangle to paint a
>> character in it, but haven't yet painted it
>>
>> If you copied the rendered state into a buffer, then cleared and painted
>> the character there, then rendered the buffer into the window as a
>> whole, the windowing system won't get a chance to see and display the
>> intermediate state.
>
> Avoiding the cursor redraws sounds much easier, but again, I'm not an
> expert on this. Perhaps Jan could comment.
Avoiding the cursor redraws must be easier. Implementing double buffering is more work.
Not rocket sience, but it would probably take a while to get it right.
Ironically we turn off the Gtk double buffering, because it only works with Gtk drawing functions,
and Emacs uses X functions. A more long term solution would be to use Cairo. There is a patch
for it, but it does not work on the trunk. Mainly because the ftfont backend is broken.
So, if there is a way to avoid cursor redraws, go for it. All ports benefit. Double buffering is a port specific solution, unless the display engine does double buffering by having two sets of glyphs and compares them to see what has really changed. Sounds like a big project.
Jan D.
next prev parent reply other threads:[~2014-02-04 22:08 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-02 1:01 bug#16621: 24.3.50; Periodic timer + overlays = flickering near point Dmitry Gutov
2014-02-02 2:33 ` Stefan Monnier
2014-02-02 2:37 ` Dmitry Gutov
2014-02-02 16:39 ` Eli Zaretskii
2014-02-03 2:12 ` Stefan Monnier
2014-02-03 5:47 ` Eli Zaretskii
2014-02-03 13:41 ` Stefan Monnier
2014-02-03 16:14 ` Eli Zaretskii
2014-02-04 3:28 ` Stefan Monnier
2014-02-04 3:44 ` Eli Zaretskii
2014-02-04 2:34 ` Dmitry Gutov
2014-02-04 3:48 ` Eli Zaretskii
2014-02-04 6:17 ` Dmitry Gutov
2014-02-04 16:00 ` Eli Zaretskii
2014-02-04 22:08 ` Jan D. [this message]
2014-02-05 3:57 ` Eli Zaretskii
2014-02-05 6:02 ` Jan Djärv
2014-02-05 15:40 ` Eli Zaretskii
2014-02-05 13:46 ` Stefan Monnier
2014-02-05 15:59 ` Eli Zaretskii
2014-02-05 18:57 ` Stefan Monnier
2014-02-05 20:00 ` Eli Zaretskii
2014-02-05 21:46 ` Stefan Monnier
2014-02-06 5:56 ` Eli Zaretskii
2014-02-06 13:08 ` Stefan Monnier
2014-02-06 14:20 ` Eli Zaretskii
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