Re: Entering emojis

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 28 Oct 2021 13:55:21 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: mattiase@acm.org, raman@google.com, schwab@linux-m68k.org, 
>     stefankangas@gmail.com, emacs-devel@gnu.org
> 
> > Like I said: the new way of formatting this script is not yet supported 
> > widely enough.
> 
> Okay, so IIUC, Unicode has decided to do something that goes against the 
> existing practice.

Looks like that, yes.

> Given the limited available manpower in that narrow subfield, I'm
> not quite sure it was the best thing to do.  Using a font with
> predefined ligatures is much easier to enter text.

I think the issue is not whether the font delivers ligatures or not,
the issue is whether the font recognizes the sequences which should
produce either ligatures or series of glyphs with offsets, when the
formatting controls are in the sequence.  It sounds like the existing
fonts don't recognize such sequences for what they are supposed to
produce.

> > AFAIU, U+13431 is the joiner to be used in that case.
> 
> But it's not a joiner, it's a non-joiner.  The logic is the opposite of 
> what Unicode decided to do: known quadrats are automatically recognized 
> and combined appropriately when their individual characters appear one 
> after the other in a string.  It's only when you want to avoid this that 
> you have to add a non-joiner.

That's not what the Unicode Standard says.

> > And you didn't answer my question: does LibreOffice with the Aegyptus 
> > font display those sequences correctly?
> >
> 
> I'm not sure what you mean by "those sequences".  The sequences in the 
> patch are rendred correctly.  The sequences in figure 11-2 of section 11.4 
> of the Unicode standard are not rendered correctly.  See the attached two 
> pictures.

OK, thanks.

So I think we should indeed install you patch, and add a comment that
if and when the fonts learn to support these formatting controls, we
should go back to the version with the controls.  Because etc/HELLO is
supposed to demonstrate our advanced text shaping and display
capabilities, not just that we can find suitable fonts for scripts.

WDYT?