Re: Contextual removal of some ligatures using fonts.handlers.otf.addfeature (LuaTeX 1.13.2)

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 12/25/2021 11:52 PM, Thomas Savary via ntg-context wrote:
> Hi Bruce and Hans !
> 
> 
> Thank you very much for your answers, that helped me a lot.
> 
> 
> In fact, though I would love to switch to ConTeXt one day, I am still 
> using LuaLaTeX — I am a slow learner and I know it will take me months 
> to be able to achieve what I need for my job with ConTeXt and can do 
> with LuaLaTeX and the Memoir class for the time being (despite sometimes 
> being irritated by LaTeX limitations or oddities).

keep in mind that context font handling and latex font handling can 
differ (and not all that is possible in context is in the generic font 
loader code); also, in (esp in lmtx) some solutions are not bound to fonts

> I need the EB Garamond variable font for future jobs, but this font, 
> provided by Google Fonts, is such a mess : kerning problems, unusable 
> OpenType features that have to be rewritten from scratch, shifts in 
> glyphs table… For sure, the original font by Georg Duffner was much 
> better, but I need the variable version. Lots of fixing necessary, but 
> thanks to fonts.handlers.otf.addfeature I have almost succeeded to make 
> it a usable Garamond.

a probably more reliable solution is to 'remove bad stuff' from the 
loaded font by running over the features and removing bad matches (which 
is less sensitive for order)

> Of course, it would be best to help Google improving this font, but I 
> don’t have time yet.

is that really a google font? afaik it doesn't originate there (unless 
it among those things that google grabs - and at some point possible 
discards)

> The actual problem was with the italic ligatures "a_s", "e_s", "é_s", 
> "i_s" and "u_s", that should occur only at the end of words and not 
> everywhere. Instead of removing the unwanted ligatures, I chose another 
> way as soon as I understood how to fully use “current” to describe not 
> only a single glyph, but a string if necessary — for instance, current={ 
> { "a", "e", "eacute", "i", "u"}, {"s"} }

ok, good that you got it working
  Hans

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