[NTG-context] new font trickery

24 Jan 2021

      Hi Jairo,

(to the list for those who want to play with it)

In addition to the metapost fotn subsystem I also made a tex variant. 
That one is currently based on setups. So, we now can use mp as well as 
tex to make fonts. Of course this is mostly for special purposes and for 
fun but both are quite efficient.

\starttext

\setupexternalfigure[directory={global,default}]

\startsetups box:demo:103
     \externalfigure[cow-brown.pdf][height=12pt]
\stopsetups

\startsetups box:demo:104
     \externalfigure[cow-black.pdf][height=10pt]
\stopsetups

\startsetups box:demo:105
     \externalfigure[mill.png][height=12pt]
\stopsetups

\startsetups box:demo:106
     \externalfigure[hacker.jpg][height=12pt]
\stopsetups

\registerboxglyph category {demo} unicode 103 \relax % rather low level 
for now
\registerboxglyph category {demo} unicode 104 \relax % rather low level 
for now
\registerboxglyph category {demo} unicode 105 \relax % rather low level 
for now
\registerboxglyph category {demo} unicode 106 \relax % rather low level 
for now

\definefontfeature[whatever][box=demo]

\definedfont[Serif*whatever]

% \enabletrackers[fonts.collecting]

\startTEXpage%[offset=0pt]
    %\hbox{g}%
     \hbox{\char103}%
     \hbox{\char104}%
\stopTEXpage

\startsetups box:demo:whatever
     \startMPcode
         picture p ; p := image (draw figure "hacker.jpg" ysized 10pt);
         fill      boundingbox p enlarged .5pt randomized 2pt withcolor 
"darkgray" ;
         clip p to boundingbox p enlarged -1pt randomized 2pt ;
         draw p ;
     \stopMPcode
\stopsetups

% in current font!

\iffontchar\font\privatecharactercode{demo:whatever}\else
     \setboxglyph {
         category {demo}
         name     {demo:whatever}
         setups   {box:demo:whatever}
     }%
\fi

\startTEXpage[offset=10pt]
     \char\privatecharactercode{demo:whatever}%
\stopTEXpage

\startTEXpage%[offset=0pt]
     \ruledhbox{\char103}
     \ruledhbox{\char104}
     \ruledhbox{\char105}
     \ruledhbox{\char106}
\stopTEXpage

\dorecurse{1000}{
     \char 103\relax \space
     \char 104\relax \space
     \char 105\relax \space
     \char 106\relax \space
}

\page

\setupalign[verytolerant,flushleft]

\dorecurse{100}{
     #1:
     \glyph yoffset -2pt `i\relax
     \glyph yoffset -3pt `j\relax\space
}

\stoptext

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