unofficial mirror of bug-gnu-emacs@gnu.org 
 help / color / mirror / code / Atom feed
From: Eli Zaretskii <eliz@gnu.org>
To: Nick Helm <nick@tenpoint.co.nz>
Cc: 28312@debbugs.gnu.org
Subject: bug#28312: 25.2; Arabic script changes when scrolling
Date: Fri, 01 Sep 2017 09:45:08 +0300	[thread overview]
Message-ID: <83lgly29zf.fsf@gnu.org> (raw)
In-Reply-To: <m2wp5jmdrt.fsf@tenpoint.co.nz> (message from Nick Helm on Fri, 01 Sep 2017 13:03:02 +1200)

> From: Nick Helm <nick@tenpoint.co.nz>
> Date: Fri, 01 Sep 2017 13:03:02 +1200
> 
> With bidi enabled, Arabic text changes unexpectedly when scrolling or
> moving point with the mouse.
> 
> Recipe:
>   Emacs -Q
>   C-h h ;visit HELLO file
>   ;use the mouse to scroll slowly
> 
> Observe the text on the line that starts with the word Arabic. As the
> buffer scrolls, some of the characters in the Arabic representations of
> the words "Arabic" and "Hello" change between at least two glyphs.

I don't see this here, but I'm not on Darwin.  Can anyone reproduce
this on GNU/Linux?

Does the character also change its shape if you move cursor across
that line, especially when the cursor moves across the character?

> Here's a quick screen cap to show what I mean:
> https://ln.sync.com/dl/22d37f320/fwujc85a-dhb63yfw-cv5vhzj5-5qsis2h8

I cannot watch this movie with the software I have installed.

> The problem goes away when I change the file local variable:
>   ;;; bidi-display-reordering: nil 

Not much sense in doing that for displaying Arabic!

> My system defaults to Geeza Pro to display Arabic script, but the
> problem also occurs with other fonts, such as Arial Unicode MS. I don't
> see the problem with other RTL scripts in the HELLO file, such as
> Hebrew.

Arabic needs shaping support from the underlying font back-end, so
(unless this will be reproduced on GNU/Linux) it sounds like something
is wrong with either the back-end Emacs uses on Darwin, or its version
you have installed, or with the support code in Emacs which is needed
for displaying complex RTL scripts such as Arabic.

FWIW, I tried Arial Unicode here, and saw no problem with that,
either.





  reply	other threads:[~2017-09-01  6:45 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-01  1:03 bug#28312: 25.2; Arabic script changes when scrolling Nick Helm
2017-09-01  6:45 ` Eli Zaretskii [this message]
2017-09-01  7:36   ` YAMAMOTO Mitsuharu
2017-09-01  8:01     ` Alexis
2017-09-01  8:16     ` Andreas Schwab
2017-09-01  8:35     ` Eli Zaretskii
2019-06-06 14:04       ` Eli Zaretskii
2019-06-09 23:56         ` Nick Helm
2019-06-10 17:27           ` Eli Zaretskii
2019-06-11 14:49             ` Eli Zaretskii
2020-08-10 14:13               ` Lars Ingebrigtsen
2017-09-01  8:16   ` Nick Helm

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

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=83lgly29zf.fsf@gnu.org \
    --to=eliz@gnu.org \
    --cc=28312@debbugs.gnu.org \
    --cc=nick@tenpoint.co.nz \
    /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 public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).