bug#71569: 30.0.50; Noto Color Emoji does not work in Emacs for Android

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Antonio Romano <n58r@pm.me> writes:

> Good evening, I've been trying to view emojis on Emacs for Android and
> noticed that colored emojis do not appear, while monochrome emojis do
> appear instead. I've only experimented with Noto Emoji Colore and Noto
> Emojis so far.
>
>
> Steps to reproduce:
>
> 1. Install both Noto Emoji (monochrome emojis) and Noto Emoji Color
> (colored emojis) and copy the two .TTF files to ~/fonts
>
> 2. Restart Emacs with -Q
>
> 3. Execute the following
>
> (set-fontset-font t 'emoji '("Noto Color Emoji" . "iso10646-1") nil
> 'prepend)
>
> 4. Try to insert emojis and notice that blank "spaces" are inserted,
> instead
>
> 5. Repeat step 3 but with "Noto Emoji" font and see how the blank
> spaces
> are filled with the respective monochrome emojis
>
>
> I'm using the latest SourceForge release of Emacs for Android.
>
> If this is not a big but a known limitation known I believe
> it's appropriate to specify it under Android section of the Emacs
> manual

The font driver doesn't yet grok color fonts, yes.  I'll see to
documenting this restriction.