bug#60781: 28.2; column-number-mode counts differently based on character encoding

bug#60781: 28.2; column-number-mode counts differently based on character encoding

[Van Ly]

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Hello,

// one right arrow key move of the cursor from the left most position
// numbers differently in column-number-mode based on character encoding

These steps reproduce the observed unexpected behavior:

* emacs -Q /tmp/example.text
* move cursor to line two at left most position, then right arrow key once
* M-x column-number-mode
* the modeline indicator shows (2,2)
* move cursor to line nine at left most position, then right arrow key once
* the modeline indicator shows (9,1)

// for cjk the column number is two
// for ascii the column number is one

* expected modeline indicator to show (2,1) and (9,1)

See attached: bug-report.text, example.text

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In GNU Emacs 28.2 (build 2, aarch64-unknown-linux-gnu, GTK+ Version 3.24.24, cairo version 1.16.0)
 of 2023-01-09 built on x23
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LIBSELINUX LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG SECCOMP SOUND
THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
  value of $LANG: C.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Text

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
time-date subr-x help-mode cl-loaddefs cl-lib help-at-pt seq byte-opt gv
bytecomp byte-compile cconv cus-start cus-load iso-transl tooltip eldoc
paren electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite emoji-zwj charscript charprop case-table
epa-hook jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice
button loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 60298 7676)
 (symbols 48 7684 1)
 (strings 32 20387 1127)
 (string-bytes 1 647752)
 (vectors 16 19483)
 (vector-slots 8 961025 171312)
 (floats 8 24 68)
 (intervals 56 498 0)
 (buffers 992 14))

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表示留下，如宋嚴羽
《滄浪詩話‧詩辯》：
「所謂不涉理路，
不落言筌者，上也。」



# 0

bug#60781: 28.2; column-number-mode counts differently based on character encoding

[Eli Zaretskii]

tags 60781 notabug
thanks

> Date: Fri, 13 Jan 2023 13:31:29 GMT
> From: Van Ly <van.ly@sdf.org>
> 
> // one right arrow key move of the cursor from the left most position
> // numbers differently in column-number-mode based on character encoding
> 
> These steps reproduce the observed unexpected behavior:
> 
> * emacs -Q /tmp/example.text
> * move cursor to line two at left most position, then right arrow key once
> * M-x column-number-mode
> * the modeline indicator shows (2,2)
> * move cursor to line nine at left most position, then right arrow key once
> * the modeline indicator shows (9,1)
> 
> // for cjk the column number is two
> // for ascii the column number is one
> 
> * expected modeline indicator to show (2,1) and (9,1)

Your expectations are incorrect.  Some characters, including the ones
in line 2 of your example file, are double-width characters, they take
up more than one column on display.  Which characters take two columns
is defined by the Unicode standard, and most fonts follow that
standard, in that the character glyphs they provide are indeed wider
than ASCII or Latin characters.  And column-number-mode counts columns
on display, it doesn't count characters.

This is not a bug, but the expected and correct behavior.

bug#60781: 28.2; column-number-mode counts differently based on character encoding

[Van Ly]

Thanks.

I will file it a bug in my idea of human centered design principle. \smiley

bug#60781: 28.2; column-number-mode counts differently based on character encoding

[Eli Zaretskii]

> Date: Sat, 14 Jan 2023 03:10:50 GMT
> From: Van Ly <van.ly@sdf.org>
> Cc: 60781@debbugs.gnu.org
> 
> 
> Thanks.
> 
> I will file it a bug in my idea of human centered design principle. \smiley

I'm therefore closing the bug.