Re: Status of the all-tex-fonts feature branch

[Pedro Andres Aranda Gutierrez]

Thanks a ton… will study carefully 
Best, /PA
Enviado desde mi iPad

> El 11 nov 2025, a las 16:01, RadioNoiseE <rne....@icloud.com> escribió:
> 
> 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 <rne....@icloud.com> wrote:
>> 
>>> On Tue, 11 Nov 2025 02:14:11 +0800,
>>> Ihor Radchenko wrote:
>>> 
>>> Huang Jing <rne....@icloud.com> 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