[XeTeX] Support of variable OpenType fonts

[Bruno Voisin]

> On 12 Jul 2022, at 22:46, Karl Berry <karl at freefriends.org> wrote:
> 
> Jonathan or Arthur or anyone can correct me, but so far as I have
> observed, no one has been working on such new xetex developments for
> years now.
> 
> If there is anyone out there with sufficient time, interest, and skill,
> a volunteer would surely be welcome. If a small grant would be any
> enticement for this particular (or other) task(s), the TeX development
> fund (tug.org/tc/devfund) is available.

If anybody wishes to take on that task, here's another possible item for the todo list: the support of colour emoji fonts.

I have not tried with other emoji fonts, but Apple's font (Apple Color Emoji.ttc in macOS) is supported by LuaHBTeX in Harf mode, but not XeTeX.

Overleaf has a very nice technical article on TeX's support of emojis

https://www.overleaf.com/learn/latex/Articles/An_overview_of_technologies_supporting_the_use_of_colour_emoji_fonts_in_LaTeX

discussing in detail why XeTeX doesn't support them (ie lack of support of raster-based OpenType colour fonts).

It would be nice if somebody were able to overcome that obstacle.

Bruno