Re: Ligature support

[Eli Zaretskii]

> From: Benjamin Riefenstahl <b.riefenstahl@turtle-trading.net>
> Date: Sat, 06 Nov 2021 14:25:11 +0100
> 
> > Possibly, but probably not.  But I don't think people will choose to use
> > fonts for programming that have fonts like that.  (Are there even any
> > monospace fonts that have such ligatures?)  But when rendering document
> > using a variable-pitch font, then yes.
> 
> That is what font "features" are for, as I understand the concept.  I
> think Emacs supports those already.  Features enable or disable stuff
> like certain ligatures.  The user can activate or deactivate features in
> the font specification to choose which ligatures to use.

We have no such mechanism in Emacs.  We pass a sequence of characters
to the shaping engine, and expect it to DTRT vis-a-vis the font and
return to use the font glyphs to display that sequence.  The only
control Lisp programs and users have here is via
composition-function-table, which determines when we use the shaping
engine for displaying one or more characters.