On 2024-11-04 10:55, Wolfgang Schuster wrote:
> Mikael Sundqvist schrieb am 04.11.2024 um 07:35:
>> Hi,
>>
>> You can try this below (from test suite), but then, as you see, also
>> upright T will move out. Not sure how/if you can control that.
>>
>> \startluacode
>>
>> local classes = fonts.protrusions.classes
>> local vectors = fonts.protrusions.vectors
>>
>> classes.rik = {
>>      vector = 'rik',
>>      factor = 1,
>> }
>>
>> vectors.rik = table.merged (
>>      vectors.quality,
>>      {
>>        [0x0054] = { 0.35, 0 }, -- T
>>      })
>>
>> \stopluacode
>>
>> \definefontfeature
>>    [default]
>>    [default]
>>    [protrusion=rik,expansion=quality]
>
> Define a feature which sets only the custom protrusion values:
>
> \definefontfeature [rik] [protrusion=quality]
>
> and create a new typeface where you apply the new feature to the 
> italic/slanted style:
>
> \definefontfamily [riktimes] [rm] [TeX Gyre Termes] 
> [sl=features:{default,rik}]
>
> Afterwards use \seupbodyfont[riktimes] to access the new typeface.
>
> Wolfgang
> ___________________________________________________________________________________ 
>

Looking a bit more, the problem is not protrusion but the bounding box. 
Look at the left side of the italic T and W, and to a lesser degree C, 
O, and Q, produced by the following.

    \usetypescript[libertinus]
    \setupbodyfont[libertinus]
    \starttext
    ¦\doloopoverlist{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
    {\it\recursestring\tf¦}\par
    ¦\doloopoverlist{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
    {\recursestring¦}

    ¦\doloopoverlist{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
    {\WORD{\it\recursestring}\tf¦}\par
    ¦\doloopoverlist{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
    {\WORD{\recursestring}¦}
    \stoptext

This may be an issue for the font maintainer, but is there anything that 
could be done within context?

-- 
Rik