Re: Unicode 13 Emoji ranges composed with wrong font on NS port

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Jimmy Yuen Ho Wong <wyuenho@gmail.com>,  emacs-devel@gnu.org
> Date: Wed, 13 Oct 2021 12:22:26 +0200
> 
> Based on what I see here, itʼs the usual suspects: eg U+261D. Itʼs not
> part of the emoji script in Emacs. The font_range change should cause
> 
>     U+261D U+FE0F
> 
> to switch to emoji presentation, but it doesnʼt since thereʼs a
> composition-function-table entry for U+261D, so the backwards looking
> entry for U+FE0F never comes into play.
> 
> Iʼm not sure how to fix this.
> 
> - We canʼt add U+261D to the emoji script.

These composition-function-table entries for these characters
come from emoji-zwj.el, so we could simply add the above sequences to
that, by suitable change in emoji-zwj.awk, right?  And then the
font_ranges trick should cause us select an Emoji font, right?

But is it worth the trouble?  IOW, do these characters have pretty
appearance when they are followed by VS-16?

I wouldn't add the characters themselves to the 'emoji' script, as
that would have much wider consequences, not necessarily good ones.
For example, I don't think that these characters, when they aren't
followed by VS-16 or something Emoji-like, should be displayed using
the Emoji fonts.

> - We could fix the backwards looking issue with
> composition-function-table (I have no idea how complex that is)

I don't think it's complicated, and I already asked Kenichi Hand about
that, hopefully he will either agree with my conclusions or explain
where I'm wrong.