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From: Alan Third <alan@idiocy.org>
To: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
Cc: 34710@debbugs.gnu.org
Subject: bug#34710: the mode line flicks on set-window-vscroll
Date: Sat, 2 Mar 2019 20:10:48 +0000	[thread overview]
Message-ID: <20190302201048.GA20712@breton.holly.idiocy.org> (raw)
In-Reply-To: <3D005746-B3FB-4915-A406-10DD0935C671@misasa.okayama-u.ac.jp>

On Sat, Mar 02, 2019 at 07:25:13PM +0900, Tak Kunihiro wrote:
> On Emacs-26.1.92 build for macOS, I see the mode line flicks when I
> scroll-up using pixel-scroll-mode and mouse wheel.  The mode line does
> not flick on scrolling-down.  I do not see this problem in
> Emacs-26.1.92 build for Windows.
> 
> macOS$ /Downloads/emacs-26.1.92/nextstep/Emacs.app/Contents/MacOS/Emacs -Q
> M-x pixel-scroll-mode
> M-: (pixel-scroll-up 1) ; => the mode line flicks
> M-: (pixel-scroll-down 1) ;=> no flick
> 
> I narrow down the problem and notice that following
> two blocks response differently.
> 
> #+begin_src emacs-lisp
> (dolist (vs (number-sequence 1 10))
>   (set-window-vscroll nil vs t)
>   (sit-for 0))
> ;; the mode line flicks
> #+end_src
> 
> #+begin_src emacs-lisp
> (dolist (vs (number-sequence 1 10))
>   (set-window-vscroll nil vs t))
> ;; no flick
> #+end_src
> 
> Do you have idea?

I believe it’s a problem with running redisplay rapidly (sit-for) and
the way we’re drawing in NS. We end up with macOS demanding a screen
update, and Emacs unable to deliver due to there being another
redisplay coming up.

The patch attached to this discussion doesn’t have the problem:

https://lists.gnu.org/archive/html/emacs-devel/2019-02/msg00354.html

However Robert Pluim reported serious performance problems with it. I
haven’t been able to replicate them.

-- 
Alan Third





  reply	other threads:[~2019-03-02 20:10 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-02 10:25 bug#34710: the mode line flicks on set-window-vscroll Tak Kunihiro
2019-03-02 20:10 ` Alan Third [this message]
2019-03-03  4:15   ` Tak Kunihiro
2019-03-04  9:06   ` Robert Pluim
2019-03-04 19:25     ` Alan Third
2019-03-04 21:07       ` Robert Pluim
2019-03-04 22:45         ` Alan Third
2019-03-05  9:06           ` Robert Pluim
2019-03-05 17:09             ` Robert Pluim
2019-03-06  8:06               ` Alan Third
2019-03-06  9:13                 ` Robert Pluim
2019-03-07  0:25 ` Tak Kunihiro

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