Re: Ligature support

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> So for having ligatures you need to set up composition-function-table
> for the characters that could/should ligate.

Yes.  And to do that, we can parse the tables in the font, apparently.
It's not obviously clear how, but it looks like harfbuzz has the
functions needed.

> But please read the TODO item: there are pitfalls here that we need to
> solve before this could be considered a reasonable user-level
> feature.  Setting up composition-function-table to produce ligatures
> for, say, "fi" and "ff" is easy for testing, but if you do that in
> production, every word with these characters, everywhere on display in
> Emacs, will display as that ligature, and that is hardly TRT.  We need
> to make this more fine-tunable.  TODO has the details.

I guess it needs some more customisation to be a per-font thing?

But first we need to parse the Gsub/Gpos tables so that we can get
started at all.

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