bug#63731: [PATCH] Support Emoji Variation Sequence 16 (FE0F) where appropriate

[Robert Pluim]

>>>>> On Mon, 05 Jun 2023 16:31:58 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> Cc: 63731@debbugs.gnu.org, steven@stebalien.com
    >> Date: Mon, 05 Jun 2023 16:12:20 +0300
    >> From: Eli Zaretskii <eliz@gnu.org>
    >> 
    >> >     Eli> So you are saying that, in our default fontset, we should 
specify that
    >> >     Eli> #xFE0E should be displayed by Noto Emoji (with Symbola as 
fallback),
    >> >     Eli> and then make sure that font_range uses the same font for the 
likes of
    >> >     Eli> #x23E9?  IOW, specify a different font for VS-15 even though 
is script
    >> >     Eli> is 'emoji'?
    >> > 
    >> > Yes, that works (and we can remove VS-15 and VS-16 from the emoji
    >> > script, so that theyʼll then be displayed via
    >> > `glyphless-char-display-control' when theyʼre on their own).
    >> 
    >> What about the rest of VS-nn? do they need to stay in 'emoji' script,
    >> and if so, why?

    Eli> And one more question: if we remove VS-16 from the emoji script, what
    Eli> will happen to the sequences like U+23E9 U+FE0F?  Isn't it true that
    Eli> we use a color Emoji font for those because VS-16 is in emoji script?

Not anymore. Now we have a forward composition rule for U+23E9
U+FE0F that triggers because U+23E9 is in the emoji script, which is
why U+23E9 U+FE0E also uses the emoji font (currently).

For non-emoji codepoints like U+203C, adding U+FE0F uses the emoji
font because U+FE0F is in the emoji script (and thereʼs no composition
rule for U+203C, so the backwards looking one for U+FE0F is used).

Robert
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