[Dev-luatex] problem with loading Chinese Fonts.

14 Aug 2007

      Hi,

I was just playing luatex with the script in
http://luatex.bluwiki.com/go/Use_a_TrueType_font
, and found some problem.

On Windows XP English Edition or Debian GNU/Linux with luatex 0.10.1 I
wrote the following script:

------------------------------------------------------------------file begins
\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
          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

           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,
              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.cidinfo = {
            registry = "Adobe",
            ordering = "Identity",
            supplement = 0,
            version = 1
          }
        end
      else
        f = font.read_tfm(name, size)
      end
    return f
    end
  )
}

%\font\times= times.ttf at 10pt \times
Like oratory, music, dance, calligraphy -- like anything that lends
its grace to language -- typography is an art that can be deliberately
misused. It is a craft by which the meanings of a text (or its absence
of meaning) can be clarified, honored and shared, or knowingly
disguised.

%\font\arial= arial.ttf at 10pt \arial
In a world rife with unsolicited messages, typography must often draw
attention to itself before it will be read. Yet in order to be read,
it must relinquish the attention it has drawn. Typography with
anything to say therefore aspires to a kind of statuesque
transparency. Its other traditional role is durability: not immunity
to change, but a clear superiority to fashion. Typography at its best
is a visual form of language linking timelessness and time.

%\font\simhei= simhei.ttf at 10pt \simhei
%中文

\bye
------------------------------------------------------------------End of file

Step 1
times.ttf for Times New Roman and arial.ttf for Arial is available in
Microsoft Windows XP, and they looks pretty well. so this script
works.

Step 2
but then I load a Chinese font, simhei.ttf. It is also available in
the English Edition of Windows XP.
and now luatex reports:
Warning: Glyph 257 is named middot which should mean it is mapped to
Unicode U+00B7, but Glyph 194 already has that encoding.

and then it crash:
This went wrong:[string "luas[0]"]:1: attempt to perform arithemetic
on field 'width'  (a nil value).
<to be read again>
                           \simhei

So it fails to compile.

Step 3
Then I found a smaller Chinese font named simkai.ttf, you can find it
in the Simplified Chinese version of Windows XP. it compiles
successfully with the Warning message but without the error message.
it generate the pdf file, but the two chinese characters are so close
(see the a.pdf I enclosed here) that they are almost in the same
place. if I change
          mag = size / 2048
to
          mag = size / 256
then the space looks right.

Step 4
I tried more Chinese ttf fonts and found that only a few can pass the
test, and among those few, the character box width seems all wrong.
So how can I make things right? or it is just a bug in luatex?

Yue Wang

[Dev-luatex] problem with loading Chinese Fonts.

Sherry Zhang