On Tue, 11 Nov 2025 22:05:55 +0800,
Pedro Andres Aranda Gutierrez wrote:
>
> [1 <text/plain; UTF-8 (quoted-printable)>]
> [2 <text/html; UTF-8 (quoted-printable)>]
> Hi
>
> Thanks a lot for tuning in...
> Answers - or maybe more questions ;-) - inline...
>
> On Tue, 11 Nov 2025 at 14:35, RadioNoiseE <[email protected]> wrote:
>
> On Tue, 11 Nov 2025 02:14:11 +0800,
> Ihor Radchenko wrote:
> >
> > Huang Jing <[email protected]> writes:
> >
> > >> How does it play with babel and polyglossia?
> > >
> > > It's not mentioned in the documents of xeCJK and luatex-ja, however I
> > > believe they do work together. From my limited testing, when loaded as
> > > packages, xeCJK and luatex-ja does no localization, thus relying on
> > > babel. However they will override the font settings by babel, which is
> > > totally acceptable.
> >
> > That actually depends. If the user of Org mode customizes fonts, it may
> > be a surprise when xeCJK/luatex-ja override the fonts. So, we might only
> > load these packages conditionally, when no font of explicitly selected.
> > Or maybe we simply put font settings _after_ xeCJK/luatex-ja is loaded.
>
> We don't need to configure fonts for babel, and it only provides
> localization. xeCJK provides the \setCJK...font control sequence while
> luatex-ja provides \set...jfont, so we can use them for font
> configuration.
>
> That was my understanding... I've done a couple of experiments based on what
> overleaf.com was providing and was able to
> start handling \setCJK...font{} with \usepackage{fontspec}. If you were so
> kind to provide a MWE for luatex-ja, I think
> we could have something reasonable for Japanese too.
Sure. This is for Chinese under LuaTeX:
\documentclass{article}
\makeatletter
\def\ltj@stdmcfont{FandolSong} % serif font
\def\ltj@stdgtfont{FandolHei} % sans serif and monospace font (usually the
same)
\def\ltj@stdyokojfm{quanjiao} % jfm
\makeatother
\usepackage{luatexja} % load after defining \ltj@std...
\usepackage{indentfirst} % convention
\usepackage[chinese,provide=*]{babel} % load after luatexja
\catcode`\^^^^200b=\active\let^^^^200b\relax % ignore zws
\parindent=2\zw % convention
\linespread{1.333} % 16pt/12pt
\begin{document}
\section{天山山脉}
位于乌鲁木齐市以东的博格达峰海拔5445米，峰上的积雪终年不化，人们称它
“雪海”。位于博格达峰山腰的天池，清澈透明，是新疆著名的旅游胜地。目前，
博格达峰自然保护区已纳入联合国“人与生物圈”自然保护区网。托木尔峰，海
拔7439米，是天山的最高峰，登山界一般承认1956年阿巴拉科夫首次登顶成功，
但也有说1938年已有苏联登山队登顶；1975年7月25日首个中国登山队登顶成
功。
\end{document}
This is for Japanese under XeTeX:
\documentclass{article}
\usepackage{luatexja} % OOTB Japanese supp
\usepackage{indentfirst} % conventions
\usepackage[japanese,provide=*]{babel} % laod after luatexja
\catcode`\^^^^200b=\active\let^^^^200b\relax % ignore zws
\parindent=\zw % convention, different from Chinese which is 2\zw
\linespread{1.333} % 16pt/12pt
\begin{document}
\section{二億圓の犬}
犬はよく訓練されたフォックス・テリアで「歐洲の驚異の犬」といわれたも
のだそうである。それを加州へ送る途中、兩會社の不注意で、途中で死んで
しまったので、それに對して、二億二千萬圓の損害賠償をしろというのが、
この訴えである。
いくらアメリカでも、こういう話は珍しいらしく、加州の話が、シカゴの新
聞にまで載ったわけである。どんな犬かは知らないが、いくら名犬でも、二
億圓の犬というのは、われわれには一寸考えが及ばない。とにかく、とんで
もない話が時々起る國である。
\end{document}
> > > 1. Under XeTeX and LuaTeX, xeCJK and luatex-ja will setup font support
> > > according to the platform (operating system) detected, and activate
> > > font, kinsoku, line-breaking support. They will not change the
> > > \baselineskip.
> > >
> > > 2. When ctex is being used, it will also configure correct
> > > \baselineskip (from the default 12pt to 16pt). It will also try to
> > > support pdfTeX.
> > >
> > > 3. Localization support provided by babel.
> > >
> > > So it's actually necessary to load babel when not using the document
> > > classes provided. It's safer to load babel first though.
> >
> > Note that babel also provides rules for typography. So,
> > xeCJK/lualatex-ja do step onto babel a bit. But, as you said, they
> > basically add missing typographical rules, so it might be reasonable.
> >
> > > Neither xeCJK nor luatex-ja is necessary for font configuration when
> > > babel is being used. Since babel only support Chinese and Japanese on
> > > LuaTeX and XeTeX with OTF support, the CJK font can be loaded the same
> > > way as latin fonts. See
> https://latex3.github.io/babel/guides/locale-chinese.html.
> >
> > > However babel is hardly ever used in Chinese or Japanese community,
> > > since their support is so, primitive. For example it does not add
> > > xkanjiskip between latin and CJK characters. Here's a relevant
> > > discussion on relying on babel for localization in the ctex community:
> > > https://github.com/CTeX-org/ctex-kit/issues/626#issuecomment-1147428749.
> >
> > My understanding from this is that we (1) always want to load xeCJK for
> > Chinese documents (what about luatex?); (2) always want to load
> > luatex-ja for Japanese (what about xetex?).
>
> We can configure luatex-ja for Chinese documents on LuaTeX, by
> changing the \parindent to 2\zw, change the default font (HaranoAji)
> to FandolSong, and change the JFM (Japanese font metric). Vice versa.
>
> As said above... I'd like to see a MWE to check.
For LuaTeX, see above. For XeTeX, Chinese:
\documentclass{article}
\usepackage{xeCJK} % OOTB Chinese support
\usepackage{indentfirst} % convention
\usepackage[chinese,provide=*]{babel} % load after xeCJK
\catcode`\^^^^200b=\active\let^^^^200b\relax % ignore zws
\parindent=2em % convention
\linespread{1.333} % 16pt/12pt
\begin{document}
\section{天山山脉}
位于乌鲁木齐市以东的博格达峰海拔5445米，峰上的积雪终年不化，人们称它
“雪海”。位于博格达峰山腰的天池，清澈透明，是新疆著名的旅游胜地。目前，
博格达峰自然保护区已纳入联合国“人与生物圈”自然保护区网。托木尔峰，海
拔7439米，是天山的最高峰，登山界一般承认1956年阿巴拉科夫首次登顶成功，
但也有说1938年已有苏联登山队登顶；1975年7月25日首个中国登山队登顶成
功。
\end{document}
and for Japanese:
\documentclass{article}
\usepackage{xeCJK} % load first
\usepackage{indentfirst} % convention
\usepackage[japanese,provide=*]{babel} % load after xeCJK
\setCJKmainfont{HaranoAjiMincho} % serif font
\setCJKsansfont{HaranoAjiGothic} % sans serif font
\setCJKmonofont{HaranoAjiGothic} % monospace font
\catcode`\^^^^200b=\active\let^^^^200b\relax % ignore zws
\parindent=1em % convention
\linespread{1.333} % 16pt/12pt
\begin{document}
\section{二億圓の犬}
犬はよく訓練されたフォックス・テリアで「歐洲の驚異の犬」といわれたも
のだそうである。それを加州へ送る途中、兩會社の不注意で、途中で死んで
しまったので、それに對して、二億二千萬圓の損害賠償をしろというのが、
この訴えである。
いくらアメリカでも、こういう話は珍しいらしく、加州の話が、シカゴの新
聞にまで載ったわけである。どんな犬かは知らないが、いくら名犬でも、二
億圓の犬というのは、われわれには一寸考えが及ばない。とにかく、とんで
もない話が時々起る國である。
\end{document}
> > >> > For the \setCJK...font declaration, I can provide a wrapper in LaTeX
> > >> > if needed, compatible with XeTeX, LuaTeX and probabily other
> > >> > engines. You will need xeCJK for this control sequence while other
> > >> > engines will not compile because it is provided by the xeCJK package.
> > >> > Under other engines, there are different control sequences used for
> > >> > font configuration (i.e., under LuaTeX thus luatex-ja, you use
> > >> > \set...jfont).
> >
> > Could you expand on "other engines will not compile"? How does it fit to
> > "compatible with XeTeX, LuaTeX, and probably other engines"?
> > (Note that inclusion or not inclusion of xeCJK can be controlled by us -
> > we know which compiler is used for export during export and can
> > conditionally include it on Elisp level)
>
> What I mean by ``other engines will not compile'' is when directly
> using \setCJK...font in the exported document, even though ctex works
> across different TeX engines, since it's xeCJK providing these
> commands, it will not compile under, i.e., LuaTeX.
>
> But as we don't use ctex now, we just need to call \setCJK...font for
> XeTeX after loading xeCJK, and \set...jfont for luatex-ja under
> LuaTeX. Since we can access the target engine through
> org-latex-compilers.
>
> Hmm... so my guess was not that wrong ;-)
>
> > >> Could you provide more details about these commands?
> > >
> > > Equivalents to \setCJK...font provided by luatex-ja are documented in
> > > English here:
> https://mirrors.ctan.org/macros/luatex/generic/luatexja/doc/luatexja-en.pdf
> > > Search for ``Tabel 1: Commands of luatexja-fontspec'' in that
> > > PDF. They are provided by luatexja-fontspec, which autoloads luatexja
> > > and fontspec.
> >
> > Ok. \setmainjfont, \setsansjfont, and \setmonojfont seems to be of
> > interest. They are direct equivalents of \setCJKmainfont,
> > \setCJKsansfont, and \setCJKmonofont. This is probably only relevant
> > when using bare bones fontspec or polyglossia to set fonts. When using
> > babel, it probably makes sense to keep using \babelfont[chinese]{rm}{...}
>
> I think we should configure fonts through xeCJK or luatex-ja provided
> interface, since they will override the babel font. Babel will not
> complain about no font specified.
>
> I'm close to designing a strategy for this. Currently, when I detect CJK
> fonts, I include xeCJK.
> So, with an MWE for Japanese fonts, it would not be too difficult to get this
> configuration right, too.
I think you need to include xeCJK even if the user does not specify
fonts, so there's a fallback/default one. (Not necessary for Chinese
under xeCJK, since it's OOTB; but for Japanese it's necessary, and
same for luatexja -- need to specify default Chinese Fandol font.)
Hopefully the MWEs help explain things.
> > > luatexja also patches LaTeX2e's NFSS2, adding CJK font
> > > support. However unless there's a specific reason we shouldn't use
> > > that in Org export results.
> >
> > That sounds concerning. What are the potential consequences?
>
> I think no observable consequences for Org export. It will not
> interfere with any existing functionality. What is does is extending
> existing framework, providing NFSS2 like interfaces for document
> classes, handling CJK font scaling, vertical typesetting, etc
> features.
>
> However I was thinking to not use luatexja-fontspec, that is we no
> longer have \set...jfont control sequences. Since luatexja-fontspec
> should be loaded after fontspec as it patches fontspec. As a
> replacement, we can use (ref. luatexja document section 8.3)
>
> \ltj@stdmcfont -> The default Japanese font for the mincho family (serif)
> \ltj@stdgtfont -> The default Japanese font for the gothic family (sans
> serif and monospace)
> \ltj@stdyokojfm -> The default JFM for horizontal direction
> \ltj@stdtatejfm -> The default JFM for vertical direction
>
> > > I'm currently having my mid-term exams, so I'll be able to work on
> > > this after Tuesday.
> >
> > No problem. I think Pedro wanted the whole thing to be in mergeable
> > state (not necessary final) before EmacsConf, but we are generally not
> > very pushy - we are all volunteers after all.
>
> >
>
> I don't want to push... it's just that I have a talk on this in EmacsConf
> and it would be cool to be able to say 'you have it in org-mode master'.
>
> > >> Org mode only supports exporting via pdflatex, xelatex, and lualatex.
> > >
> > > Then my idea is to drop ctex, and use xeCJK or luatex-ja with babel.
> > > These two packages support both Chinese and Japanese, while xeCJK
> > > comes with out-of-the-box Chinese support and luatex-ja comes with
> > > out-of-the-box Japanese support.
> >
> > Good.
> >
> > > pdfTeX support is also feasible, through the CJK package, which is
> > > used by ctex as well.
> >
> > Note that pdfTeX is something we are not certain about. I wish we could
> > do it, but it seems tricky. We will need to work out how we want to
> > design the pdftex support. Tentatively, we may add a field to
> > `org-latex-language-alist' where standard per-language config will be
> > stored and loaded according to #+LANAGUAGE settings (note that there
> > might be multiple languages in one document).
>
> CJK support on pdfTeX would require appropriate tfm, then we should be
> able to use \pdfmapline to setup CJK font. It is tricky somehow.
>
> > --
> > Ihor Radchenko // yantar92,
> > Org mode maintainer,
> > Learn more about Org mode at <https://orgmode.org/>.
> > Support Org development at <https://liberapay.com/org-mode>,
> > or support my work at <https://liberapay.com/yantar92>
>
> Best, /PA
>
> --
> Fragen sind nicht da, um beantwortet zu werden,
> Fragen sind da um gestellt zu werden
> Georg Kreisler
>
> "Sagen's Paradeiser" (ORF: Als Radiohören gefährlich war) => write BE!
> Year 1 of the New Koprocracy
