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bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction
From: |
Stephen Berman |
Subject: |
bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction |
Date: |
Sun, 25 Feb 2024 17:22:45 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
In a buffer that contains bidirectional text, setting
bidi-paragraph-direction to 'left-to-right aligns the RTL text with the
left margin like the LTR text; see the first sexp below and the top
buffer in the attached screenshot.
Another alternative to get this alignment is to leave
bidi-paragraph-direction at its default value of nil and use a space
display specification with a suitable value for the :align-to property,
but this requires a calculation that seems to depend at least on the
font used and the values of `window-width' and `string-width' for the
string used (or the corresponding pixel-width values); see the second
sexp below and the middle buffer in the attached screenshot.
It's also possible to avoid this calculation and use an :align-to value
of 0 in combination with setting bidi-paragraph-direction to
'left-to-right; see the third sexp below and the bottom buffer in the
attached screenshot. However, as the screenshot shows, this last
alternative breaks Arabic text shaping, at least for the fonts I tried
(Noto Naskh Arabic, DejaVu Sans and Amiri). If this is not an Emacs bug
but a limitation of the current display engine or a HarfBuzz bug,
perhaps it should be noted in etc/PROBLEMS.
(let* ((a "السّلام عليكم")
(b "Hello")
(buf (get-buffer-create "Test1")))
(with-current-buffer buf
(erase-buffer)
(setq bidi-paragraph-direction 'left-to-right)
(insert a "\n\n" b)
(switch-to-buffer buf)))
(let* ((a "السّلام عليكم")
(wa (+ (- (window-width) (string-width a)) 0.75))
(b "Hello")
(buf (get-buffer-create "Test2")))
(with-current-buffer buf
(erase-buffer)
(insert (propertize " " 'display `(space :align-to ,wa)) a "\n\n" b)
(switch-to-buffer buf)))
(let* ((a "السّلام عليكم")
(b "Hello")
(buf (get-buffer-create "Test3")))
(with-current-buffer buf
(erase-buffer)
(setq bidi-paragraph-direction 'left-to-right)
(insert (propertize " " 'display `(space :align-to 0)) a "\n\n" b)
(switch-to-buffer buf)))
Screenshot_2024-02-25_15-28-01.png
Description: PNG image
In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.38, cairo version 1.18.0) of 2024-02-20 built on strobelfs2
Repository revision: d9afa1f30fdf9d00b447fea0a8343397333e172f
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101009
System Description: Linux From Scratch r12.0-112
Configured using:
'configure -C --with-xwidgets 'CFLAGS=-Og -g3'
PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'
Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER
PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM XWIDGETS GTK3 ZLIB
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction,
Stephen Berman <=
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Eli Zaretskii, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Stephen Berman, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Eli Zaretskii, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Stephen Berman, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Eli Zaretskii, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Stephen Berman, 2024/02/25
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Eli Zaretskii, 2024/02/26
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Stephen Berman, 2024/02/26
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Eli Zaretskii, 2024/02/26
- bug#69384: 30.0.50; :align-to and bidi-paragraph-direction interaction, Stephen Berman, 2024/02/26