Re: Fallback fonts in LaTeX export for non latin scripts

[Ihor Radchenko <yantar92@posteo.net>]

Juan Manuel Macías <maciaschain@posteo.net> writes:

> ...In any
> case, the fonts issue is the most delicate part. What default fonts to
> add to the list? Here the user's taste or preferences would influence.

Commonly available libre fonts look like a good candidate.

> It must also be taken into account that if one has typographical
> scruples, not all fonts match each other. For design purposes, I mean.
> The Computer Modern, which is a modern style font (similar to the Didot
> or Bodoni), does not usually pair well with (for example) a Garamond,
> which is in the Renaissance style. That's why I think the best solution
> would be to offer a basic defcustom, based on the purely utilitarian,
> and let the user modify or extend it according to their taste,
> preferences or convenience.

+1.

> Another thing to keep in mind is the following. Offering basic
> readability based on the unicode scripts means that we rely on scripts
> and not languages. For example, the Cyrillic script covers several
> languages, as you well know: Russian, Bulgarian, etc. The Latin script
> is used for languages as diverse as English or Vietnamese. The choice of
> font based on the script is a low-level LuaTeX functionality, that is,
> it does not add features specific to each language, such as hyphenation
> patterns. This means that long texts in (for example) Cyrillic or Greek
> are not justified well because LaTeX does not know how hyphenate them:
> ...
> There is another possibility that I am working on in parallel: relying
> on languages instead of scripts. This would add both readability and
> support for each particular language. There could be two options for the
> user: a basic one (the low level one, based on scripts: ensures
> readability but the document may not look pretty) and an advanced one,
> based on language support. Something like this occurred to me:
>
> #+LaTeX_Header: % !enable-fonts-for ancientgreek russian:Old Standard
>  arabic

We already have #+language keyword and
`org-latex-guess-babel-language'/`org-latex-guess-polyglossia-language'.
May as well have default fonts for a given language.

As for multiple languages, do we actually support this?

>> What will happen if LuaTeX is not installed on the system?
>
> Yes, there should be some kind of warning. Also it's not just LuaTeX,
> but certain packages for fonts and multilingual support. The problem is
> that the different versions of TeX live cooked in the distros 
> usually name these packages differently. This is another added problem...
> Arch or Gentoo offer a more vanilla TeX live.

We might use `org-latex-known-warnings'.

>> Also, just to double check, is LuaTeX fully compatible to LaTeX? That
>> is, if we have an existing org file using LaTeX-specific commands and
>> packages, will it work with LuaTeX?
>
> Yes, it is fully compatible, except that LuaLaTeX does not need to load
> the fontenc or inputenc packages. LuaTeX is intended to be the natural
> replacement for pdfTeX. The latest edition of The LaTeX Companion is
> already very focused on LuaTeX. And 90% of the new LaTeX packages that
> are uploaded to CTAN only work in LuaLaTeX. One of the essential
> advantages of LuaTeX is that TeX now (finally!) has a simple scripting
> language. With a little Lua you can achieve very low level things in TeX
> that were horribly complicated in 'pure TeX'.

Then, we might even consider LuaTeX as the new default for
`org-latex-compiler'.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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