Re: reencode fonts with fonts.trigger

[Hans Hagen <pragma@wxs.nl>]

On 22-2-2011 4:22, Ulrike Fischer wrote:
> Hello,
>
> Khaled had another idea to manipulate (reencode) fonts: He suggested
> to put a function in fonts.trigger. (Example below). I have some
> questions regarding this example:

I'll add the following to the luatex-fonts code. It demonstrates how to 
use postprocessing hooks. (It should work with the current code, unless 
you define multiple mapping of the same font, for which i've added a 
patch).

\startluacode
     local reencodings     = { }
     fonts.enc.reencodings = reencodings

     local function specialreencode(tfmdata,value)
         -- we forget about kerns as we assume symbols and we
         -- could issue a message if ther are kerns but it's
         -- a hack anyway so we odn't care too much here
         local encoding = value and reencodings[value]
         if encoding then
             local temp = { }
             local char = tfmdata.characters
             for k, v in next, encoding do
                 temp[k] = char[v]
             end
             for k, v in next, temp do
                 char[k] = temp[k]
             end
             -- if we use the font otherwise luatex gets confused so
             -- we return an additional hash value for fullname
             return string.format("reencoded:%s",value)
         end
     end

     local function reencode(tfmdata,value)
         tfmdata.postprocessors = tfmdata.postprocessors or { }
         table.insert(tfmdata.postprocessors,
             function(tfmdata)
                 return specialreencode(tfmdata,value)
             end
         )
     end

     table.insert(fonts.manipulators,"reencode")
     fonts.initializers.base.otf.reencode = reencode
\stopluacode

\startluacode
     fonts.enc.reencodings["mychess"] = {
         [75] = 81,
         [81] = 75,
     }
\stopluacode

\starttext

{\font\test=file:SkakNew-Figurine.otf at 50pt                  \test QK 
\par}
{\font\test=file:SkakNew-Figurine.otf:reencode=mychess at 50pt \test QK 
\par}

\stoptext


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