Re: Ligature support

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> There's no limit to the number of these strings that fonts support, so
> if this hypothetical minor mode were to "list them all", it'd
> basically be the same as running all text through harfbuzz.  Which we
> don't want to do in general.  Ergo the need to have a per-font
> ligature table.

Well, that doesn't follow.  Once we have a way to dump the ligature
tables, we know what ligatures the fonts the user has loaded have (in
total).  A typical user won't be loading more than a handful of fonts,
so the number of ligatures at any point won't be more than a few
hundred.

And since it's harmless (just takes a bit more time) to give a sequence
to hb_shape for a font that doesn't have the ligature, we don't need a
per-font thing.

But the user may want to switch ligatures off completely, or per a
buffer/mode basis, so we do need some extra support for that.  The
primary thing here, though, is to get at the ligature data in an
efficient manner.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no