On 2025-04-26 12:51, Eli Zaretskii via Unicode wrote:
From: Dilyan Palauzov <b...@bapha.be>
Cc: unicode@corp.unicode.org
Date: Sat, 26 Apr 2025 12:00:50 +0300
From: Eli Zaretskii <e...@gnu.org>
Subject: Re: Is emoji +VC15, +VC16, without VC one or two columns with
monospace font?🏝️
Date: 26/04/25 10:02:48
I think you have very outdated mental model of how the Windows console works
and how it represents and encodes characters.
In particular, the width of a character is NOT determined by the length of its
byte sequence, but by the font glyphs used to display those characters.
I am confused. Does the width of an emoji/a character depend on the font (thus
font designers decide this), or does it depend on EastAsianWidth.txt ?
It depends on the font, but the font is supposed to go by what
EastAsianWidth.txt says.
It is worse. We are discussing monospaced fonts, and so terminals may
select where to display each characters (skipping all font hints) and
overwriting part of character.
Also note: I do not like the division Unix/non-Unix:. "Unix" terminal
had different interpretations. E.g. if we look the initial Unicode
support of xterm (so the mother of many "unix pseudoterminals), we learn
that it supported only "Unicode level 1" (and obsolete terminology in
old Unicode standards, or just in ISO). So it did interpret each
codepoint independently (so no combining codepoints).
Also a good documentation on width of characters in terminals: problems,
solutions, and interpretation of width in many implementations, from
gosthy (the new kid in the block):
https://mitchellh.com/writing/grapheme-clusters-in-terminals.
giacomo
