Re: [NTG-context] Broken kerning if hz is turned on?

2 Jun 2019

      On 6/2/2019 8:36 AM, Mikael P. Sundqvist wrote:
...
On Mon, May 20, 2019 at 9:55 PM Wolfgang Schuster 
mailto:wolfgang.schuster.lists@gmail.com> wrote:
Mikael P. Sundqvist schrieb am 20.05.2019 um 21:41:
     > Hi,
     >
     > attached is the result of running latest lmtx on
     >
     >
    \definefontfeature[default][default][protrusion=quality,expansion=quality]
    \definefontfeature [default] [default] [threshold=20,expansion=quality]
     > \setupalign[hz]
     > \setupbodyfont[lucidaot]
     >
     > \starttext
     > Gauss öppnade med denna studie ett helt nytt fält inom matematiken,
     > det som
     > handlar om \emph{elliptiska funktioner} och \emph{modulära former}.
     > \stoptext
     >
     > What happens with the space between the characters in "studie", that
     > becomes "s tudie"? The spacing between some other characters are
    also
     > off (ma tematiken), but not as much as in studie.
    It's a problem with Lucida Opentype which lacks kerning (I reported the
    same problem a while ago).
Wolfgang
Hi,
thank you Wolfgang (I just realized I only sent my thank you to you 
privately)!
Your threshold=20 solved that particular case. But look at the following 
example:
\definefontfeature[default][default][threshold=20,protrusion=quality,expansion=quality,lnum=yes,itlc=yes]
\setupalign[hz,hanging,line,height]
\definebodyfontenvironment[9bp][interlinespace=12bp]
\setupbodyfont[lucidaot,9bp]
\starttext
Gränsvärde föreligger i en inre punkt i definitionsmängden om och endast
om höger- och vänstergränsvärde existerar där och är lika.
\stoptext
I attach the output (latest lmtx). The word "endast" shows up as "endas t".
So, what does this threshold do? I can play with the 20. If I change it 
to 5 it looks better here (not perfect), but my document is approx. 250 
pages, so, I fear it will break somewhere else...
I hope that this does not mean that the Lucida font turns out to be 
useless :(
Lucida does without kerning so where in other fonts we have more of less 
tight boundingboxes + kerns, in lucida we have large side bearings and 
in that case widening works out a bit different visually (thicker 
vertical strokes as usual with hz + expanded built in side bearings), 
definitely on screen.
Now, one thing that happens in the backend is that glyphs are output as 
sequences and scaled as whole and occasionally the starting points get 
synchronized .. this is what threshold deals with.

Anyway, I might improve thinsg over time as in context lmtx we have a 
bit more control over matters.

One can argue if intercharacter kerns have to be stretched in other 
cases but in context that is configureable.

Hans

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