[luatex] How to query fonts.handlers

[Henri Menke]

I have a working ConTeXt solution now, but I can't get the same thing to
work in plain LuaTeX.

\startluacode
fonts.handlers.otf.addfeature {
    name = "ktest",
    type = "kern",
    data = {
        ["t"] = { ["e"] = 500 },
    }
}
\stopluacode

\definefontfeature[ktest][ktest=yes]

\definefont[1][Serif*ktest]

\starttext

\1 test \ctxlua{
     local fnt = font.current()
     local tfmdata = fonts.hashes.identifiers[fnt]
     local t = string.byte("t")
     local e = string.byte("e")
     local kern = 0
     for _,kind in pairs(table.keys(tfmdata.shared.rawdata.lookupcache)) do
         kern = kern + fonts.handlers.otf.getkern(tfmdata,t,e,kind)
     end
     context(kern / tfmdata.parameters.factor) % 500
}

\stoptext


On 6/02/19 12:12 PM, Ulrike Fischer wrote:
> Am Wed, 6 Feb 2019 10:41:44 +1300 schrieb Henri Menke:
> 
>> Is there a way to query the lookups?
> 
> You are the lua guy ;-). But looking in the fontloader, I think the
> generic function to query the lookups is
> 
>  local function getgsub(tfmdata,k,kind,value)
> 
> and this is then used by getkern.
> 
> There is also a otf.collectlookups.  
>