Re: alternate to font feature file for glyph substitution ?

[Hans Hagen <pragma@wxs.nl>]

On 4/28/2016 4:08 PM, jfbu wrote:
> Hi,
>
> how should I go at the Plain TeX level about implementing
> the following glyph substitution which I formerly expressed
> in a font feature file:
>
> languagesystem DFLT dflt;
> languagesystem latn dflt;
>
> feature oneb {
>   sub one by one.ss01;
> } oneb;
>
> The font is Vollkorn, a Plain LuaTeX file which worked in TL2015 would be
>
> \input luaotfload.sty
> \font\x="Vollkorn:script=latn;language=DFLT;+tlig;featurefile=vollkornlua.fff;+oneb;"
> \x 123
> \bye
> % Local Variables:
> % TeX-engine: luatex
> % End:
>
> The glyph for digit 1 is modified and picked in stylistic set 1. I don't want
> to globally switch to that stylistic set, I am only interested into digit 1.

\starttext

\startluacode
     fonts.handlers.otf.addfeature {
         name = "oneb",
         type = "substitution",
         data = {
             ["one"] = "one.ss01",
         }
     }
\stopluacode

% context

\definefontfeature[default-oneb][default][oneb=yes]
\definefontfeature[default-ss01][default][ss01=yes]

\definedfont[name:vollkorn*default]      123\par
\definedfont[name:vollkorn*default-oneb] 123\par
\definedfont[name:vollkorn*default-ss01] 123\par

% non context

\font\foo=name:vollkorn:mode=node;kern=yes;liga=yes;          \foo 123\par
\font\foo=name:vollkorn:mode=node;kern=yes;liga=yes;oneb=yes; \foo 123\par

\stoptext

> My use case is more with LuaLaTeX+fontspec, but if I am explained
> a Plain LuaTeX approach I can at least forward to Will Robertson
> who maintains fontspec and cross my fingers that it trickles down
> back to me at some point via update of fontspec, or luatex, or luaotfload,
> ...

I don't know how they do it there but you need to define some lua (as 
above) and then enable that feature when defining the font.

> Please CC to me as although I asked for (temporary) list inscription
> I might not yet be registered.
>
> I am aware of https://mailman.ntg.nl/pipermail/ntg-context/2016/083952.html
> but can't work it out from there.
>
> Jean-François
>
>
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>


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                                           Hans Hagen | PRAGMA ADE
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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
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