bug#39799: 28.0.50; Most emoji sequences don’t render correctly

[Robert Pluim]

>>>>> On Tue, 21 Sep 2021 14:58:35 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Mike FABIAN <mfabian@redhat.com>
    >> Cc: Eli Zaretskii <eliz@gnu.org>,  rgm@gnu.org,  39799@debbugs.gnu.org
    >> Date: Tue, 21 Sep 2021 13:48:17 +0200
    >> 
    >> > Iʼve just pushed a change to master that should fix (almost) all the
    >> > issues with displaying emoji sequences (except for keycaps). Feedback
    >> > welcome.
    >> 
    >> Should that also fix the skin tones?

    Eli> It should, and I thought HarfBuzz on Cairo already supported that?

It does, but with 'Noto Color Emoji' it doesnʼt work for all
codepoints.

    Eli> Can you try this with hb-view and see if HarfBuzz produces a single
    Eli> glyph/grapheme from this sequence?

For reference, since the documentation of hb-view is sadly lacking:

hb-view  --output-file=foo.svg --font-size=14 \
/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf  -u 1f469

produces a glyph with no skin tone. And

hb-view  --output-file=foo.svg --font-size=14 \
/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf  -u 1f469,1f3fd

Produces one with a medium tone. The skin tones are working for other
code points, so I donʼt know what's causing this particular problem.

Robert
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