Re: [Dev-luatex] bug with \ifcsname, ttf font spacing problems, and catcode initialisation for utf8 beyond ascii

13 Sep 2007

      Olivier Binda wrote:
...
Hello...
I have been testing luatex some more and I have made the following 
discoveries :
A) The \ifcsname macro doesn't behave as it should when you use non 
ascii char between \ifcsname and \endcsname,
as you can see if you try to luatex this minimal file :
\expandafter\def\csname A人\endcsname{success}%
1) % succeeds
\csname A人\endcsname
\par
2) % fails...this is a \ifcsname bug
\ifcsname A人\endcsname
it should write this but it doesn't
\else
it writes this and it shouldn't% it goes this way, sigh....
\fi
\bye
indeed, this does not work; if i remember right we ran into this a while 
ago but it was never solved; should be on the todo list
...
B) non-ascii utf8 char don't seem to have their catcodes initialized to 
"letter" (catcode 11).
Is this normal ? Is it a bug ? a feature ?
this is on purpose; you have to initialize anyway since not all 
characters are letters;
...
XeTeX initializes all non ascii char as letters. This is quite usefull 
(and quite logical too).
Shouldn't it be the same in luatex, at least for the sake of compatibility ?
catcodes, lc/uccodes etc are to be initialized, and this is something 
for a macropackage to deal with
...
\pdfoutput1
\directlua0{
callback.register('define_font',
    function(name, size)
      filename=kpse.find_file(name,"truetype fonts")
      if (filename) then 
         if (size < 0) then size = (- 655.36) * size end
        ttffont = fontforge.to_table(fontforge.open(filename))
        if ttffont then
          f = { }
          f.name = ttffont.fontname
          f.fullname = ttffont.names[1].names.fullname
          f.parameters = { }
          f.designsize = size
          f.size = size
          direction = 0
^ lokks wrong to me ... this defined direction as global var
...
f.parameters.slant = 0
          f.parameters.space = size * 0.25
          f.parameters.space_stretch = 0.3 * size
          f.parameters.space_shrink = 0.1 * size
          f.parameters.x_height = 0.4 * size
          f.parameters.quad = 1.0 * size
          f.parameters.extra_space = 0
          f.characters = { }
          mag = size / 2048
maybe this is wrong
...
names_of_char = { }
          for char, glyph in pairs(ttffont.map.map)
          do
            names_of_char[ttffont.glyphs[glyph].name]
              = ttffont.map.backmap[glyph]
          end
names_of_glyph = { }
          for char, glyph in pairs(ttffont.map.map)
          do
            names_of_glyph[ttffont.glyphs[glyph].name]
              = glyph
          end
for char, glyph in pairs(ttffont.map.map)
          do
            glyph_table = ttffont.glyphs[glyph]
f.characters[char] = {
              index = glyph,
              width = glyph_table.width * mag,
maybe something funny with your mag, try to set this so 10000 or so, 
just for testing
...
name = glyph_table.name,
            }
            if glyph_table.kerns then
              local kerns = { }
              for _, kern in pairs(glyph_table.kerns)
              do
                kerns[names_of_char[kern.char]] = kern.off * mag
              end
            f.characters[char].kerns = kerns
            end
          end
          f.filename = filename
          f.type = 'real'
          f.format = 'truetype'
          f.embedding = "full"
          f.cidinfo = {
            registry = "Adobe",
            ordering = "Identity",
            supplement = 0,
            version = 1
          }
        end  
      else 
        f = font.read_tfm(name, size)
      end 
    return f
    end
  )
}
\font\myfont=skullz.ttf at 8pt
\myfont
abcdefABCDEF %%% it prints but the all the chars are stacked upon 
another (they must have near 0pt width).

...
What could be wrong ?
a lot of things ... put some prints in the code, tracing ..
...
D) Please, could you put more code snipets in the luatex manual (this 
piece of code from yannis would be a good candidate) ?
the manual is a ref manual and will not have many examples

by the time that we release the first formal version, we will provide 
code that works in plain tex; we will also write a book about luatex and 
that will hav emore samples
...
I welcome Yannis' decision to build a luatex wiki and it would be even 
nicer if someone knowledgeable wrote a little luatex macro library to do 
(the right way) basic things like : loading utf/opentype fonts....
To help beginners jump on the luatex bandwagon....
well, there's a truckload of experimental code in the context 
distribution (and i expect the context wiki also to have example code), 
and we will make much of that generic, but as said, mid next year is the 
agenda ... keep in mind that for a while font supprt changes, probably 
more or less stable next month

eventually macro packages have to provide the basic code (we don't 
expect each users to write lua code for each font -)

Hans

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