revised T42 support

[Werner LEMBERG]

The attached file, ttf.cc, contains completely revised support for
conversion of TTFs to T42 fonts.  It now follows the specs exactly,
and it seems to work.  Please test.  Han-Wen, some parts in the code
are tagged as `FIXME' -- please fix it: It's mainly related to static
vs. dynamic arrays, and I simply don't have enough time to dig into
the sources, finding out how to do that elegantly in lilypond's C++.
BTW, this is the reason why I haven't checked in the file into the git
repository.  Additionally, the code is quite verbose to make it easily
understandable; maybe it can be streamlined further in case this is
desirable.

The following changes have been applied:

  . In print_header(), the various dictionary values are now correct;
    they have been incorrectly scaled.  The font revision value is now
    handled as a 16.16 fixed-scale value.

  . t42_write_table() (which was only present in Han-Wen's git branch)
    has been completely rewritten; as can be seen, much more has to be
    done than previously expected...  I've changed the layout of the
    /sfnts array to use the same format as FontForge; this has helped
    a lot during debugging.

  . It was necessary to extend print_body() a lot; we have to
    construct our own TTF header.  It is perhaps overkill to compute
    the correct checksums, but...

  . Glyph index 0 is now always called `.notdef'.


      Werner

/*
  ttf.cc --  implement ttf -> pfa routine.

  source file of the GNU LilyPond music typesetter

  (c) 2005--2007 Han-Wen Nienhuys <address@hidden>
*/

#include "freetype.hh"

#include <freetype/tttables.h>

#include "memory-stream.hh"
#include "warn.hh"
#include "lily-guile.hh"
#include "main.hh"
#include "open-type-font.hh"


Index_to_charcode_map
make_index_to_charcode_map (FT_Face face)
{
  Index_to_charcode_map m;
  FT_ULong charcode;
  FT_UInt gindex;

  FT_CharMap current_cmap = face->charmap;
  FT_Select_Charmap (face, FT_ENCODING_UNICODE);

  int j = 0;
  for (charcode = FT_Get_First_Char (face, &gindex); gindex != 0;
       charcode = FT_Get_Next_Char (face, charcode, &gindex))
    {
      m[gindex] = charcode;
      j ++;
    }
  FT_Set_Charmap (face, current_cmap);

  return m;
}

/*
  Based on ttfps by Juliusz Chroboczek
*/
static void
print_header (void *out, FT_Face face)
{
  lily_cookie_fprintf (out, "%%!PS-TrueTypeFont\n");

  TT_Postscript *pt
    = (TT_Postscript *) FT_Get_Sfnt_Table (face, ft_sfnt_post);

  if (pt->maxMemType42)
    lily_cookie_fprintf (out, "%%%%VMUsage: %d %d\n", 0, 0);

  lily_cookie_fprintf (out, "%d dict begin\n", 11);
  lily_cookie_fprintf (out, "/FontName /%s def\n",
                       FT_Get_Postscript_Name (face));

  lily_cookie_fprintf (out, "/Encoding StandardEncoding def\n");
  lily_cookie_fprintf (out, "/PaintType 0 def\n");
  lily_cookie_fprintf (out, "/FontMatrix [1 0 0 1 0 0] def\n");

  TT_Header *ht
    = (TT_Header *)FT_Get_Sfnt_Table (face, ft_sfnt_head);

  lily_cookie_fprintf (out, "/FontBBox [%lf %lf %lf %lf] def\n",
                       float (ht->xMin) / ht->Units_Per_EM,
                       float (ht->yMin) / ht->Units_Per_EM,
                       float (ht->xMax) / ht->Units_Per_EM,
                       float (ht->yMax) / ht->Units_Per_EM);

  lily_cookie_fprintf (out, "/FontType 42 def\n");
  lily_cookie_fprintf (out, "/FontInfo 8 dict dup begin\n");
  lily_cookie_fprintf (out, "/version (%.3f) def\n",
                       ht->Font_Revision / 65536.0);

#if 0
  if (strings[0])
    {
      lily_cookie_fprintf (out, "/Notice (");
      fputpss (strings[0], out);
      lily_cookie_fprintf (out, ") def\n");
    }
  if (strings[4])
    {
      lily_cookie_fprintf (out, "/FullName (");
      fputpss (strings[4], out);
      lily_cookie_fprintf (out, ") def\n");
    }
  if (strings[1])
    {
      lily_cookie_fprintf (out, "/FamilyName (");
      fputpss (strings[1], out);
      lily_cookie_fprintf (out, ") def\n");
    }
#endif

  lily_cookie_fprintf (out, "/isFixedPitch %s def\n",
                       pt->isFixedPitch ? "true" : "false");
  lily_cookie_fprintf (out, "/UnderlinePosition %lf def\n",
                       float (pt->underlinePosition) / ht->Units_Per_EM);
  lily_cookie_fprintf (out, "/UnderlineThickness %lf def\n",
                       float (pt->underlineThickness) / ht->Units_Per_EM);
  lily_cookie_fprintf (out, "end readonly def\n");
}

#define CHUNKSIZE 65534

const FT_ULong FT_ENC_TAG (glyf_tag, 'g', 'l', 'y', 'f');
const FT_ULong FT_ENC_TAG (head_tag, 'h', 'e', 'a', 'd');
const FT_ULong FT_ENC_TAG (loca_tag, 'l', 'o', 'c', 'a');

static
void t42_write_table (void *out, FT_Face face, unsigned char const *buffer,
                      size_t s, bool is_glyf,
                      FT_ULong head_length, FT_ULong loca_length)
{
  FT_UShort chunks[100];                /* FIXME: use dynamic array */
  FT_UShort cur_chunk_idx;

  if (is_glyf)
    {
      /* compute chunk sizes */
      unsigned char *head_buf = new unsigned char[head_length];
      FT_Error error = FT_Load_Sfnt_Table(face, head_tag, 0, head_buf, NULL);
      if (error)
        programming_error ("FT_Load_Sfnt_Table (): error.");

      /* we access the lower byte of indexToLocFormat */
      bool long_offsets = head_buf[4*4 + 2*2 + 2*8 + 4*2 + 3*2 + 1] == 1;

      delete[] head_buf;

      unsigned char *loca_buf = new unsigned char[loca_length];
      error = FT_Load_Sfnt_Table(face, loca_tag, 0, loca_buf, NULL);
      if (error)
        programming_error ("FT_Load_Sfnt_Table (): error.");

      unsigned char *p = loca_buf;
      unsigned char *endp = loca_buf + loca_length;
      cur_chunk_idx = 0;

      FT_ULong offset = 0, last_offset = 0, last_chunk = 0;
      while (p < endp)
      {
        if (long_offsets)
          {
            offset = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
            p += 4;
          }
        else
          {
            offset = ((p[0] << 8) | p[1]) << 1;
            p += 2;
          }
        if (offset > last_chunk + CHUNKSIZE)
          {
            chunks[cur_chunk_idx ++] = last_offset - last_chunk;
            last_chunk = last_offset;
            assert (cur_chunk_idx < 100);/* FIXME: only for static arrays */
          }
        last_offset = offset;
      }
      chunks[cur_chunk_idx] = s - last_chunk;

      delete[] loca_buf;
    }
  else if (s > CHUNKSIZE)
    {
      cur_chunk_idx = 0;
      FT_ULong rest = s;
      while (rest > CHUNKSIZE)
        {
          chunks[cur_chunk_idx ++] = CHUNKSIZE;
          rest -= CHUNKSIZE;
        }
      chunks[cur_chunk_idx] = rest;
    }
  else
    chunks[0] = CHUNKSIZE;

  lily_cookie_fprintf (out, "\n"
                            " <");

  int l = 0;
  static char xdigits[] = "0123456789ABCDEF";
  cur_chunk_idx = 0;

  for (size_t j = 0; j < s; j++)
    {
      if (l >= chunks[cur_chunk_idx])
        {
          lily_cookie_fprintf (out, "\n"
                                    " 00>\n"
                                    " <");
          l = 0;
          cur_chunk_idx ++;
        }

      if (l % 31 == 0)
        lily_cookie_fprintf (out, "\n"
                                  "  ");

      /* lily_cookie_fprintf (out,"%02X",(int)buffer[j]) is too slow */
      lily_cookie_putc (xdigits[(buffer[j] & 0xF0) >> 4], out);
      lily_cookie_putc (xdigits[buffer[j] & 0x0F], out);

      l ++;
    }

  /* pad to four-byte boundary */
  while ((s ++) % 4 != 0)
    lily_cookie_fprintf (out, "00");

  lily_cookie_fprintf (out, "\n"
                            "  00\n"
                            " >");
}

static void
print_body (void *out, FT_Face face)
{
  FT_UInt idx = 0;
  FT_ULong head_length = 0, loca_length = 0;
  FT_ULong tag, length;
  FT_ULong lengths[100], tags[100];     /* FIXME: use dynamic arrays */

  /*
    we must build our own TTF header -- the original font
    might be a TTC where tables are not contiguous, or the font
    contains tables which aren't indexed at all
   */
  while (FT_Sfnt_Table_Info(face, idx, &tag, &length)
         != FT_Err_Table_Missing)
  {
    assert (idx < 100);                 /* FIXME: only for static arrays */
    lengths[idx] = length;
    tags[idx ++] = tag;
    if (tag == head_tag)
      head_length = length;
    else if (tag == loca_tag)
      loca_length = length;
  }

  FT_ULong hlength = 12 + 16 * idx;

  unsigned char *hbuf = new unsigned char[hlength];
  unsigned char *p;

  hbuf[0] = 0x00;                       /* version */
  hbuf[1] = 0x01;
  hbuf[2] = 0x00;
  hbuf[3] = 0x00;
  hbuf[4] = (idx & 0xFF00) >> 8;        /* numTables */
  hbuf[5] = idx & 0x00FF;

  FT_UInt searchRange, entrySelector, rangeShift;
  FT_UInt i, j;
  for (i = 1, j = 2; j <= idx; i++, j <<= 1)
    ;
  entrySelector = i - 1;
  searchRange = 0x10 << entrySelector;
  rangeShift = (idx << 4) - searchRange;

  hbuf[6] = (searchRange & 0xFF00) >> 8;
  hbuf[7] = searchRange & 0x00FF;
  hbuf[8] = (entrySelector & 0xFF00) >> 8;
  hbuf[9] = entrySelector & 0x00FF;
  hbuf[10] = (rangeShift & 0xFF00) >> 8;
  hbuf[11] = rangeShift & 0x00FF;

  p = &hbuf[12];

  FT_ULong checksum, font_checksum = 0;

  FT_ULong offset = hlength;            /* first table offset */

  for (FT_UInt i = 0; i < idx; i++)
  {
    /* here, the buffer length must be a multiple of 4 */
    FT_ULong len = (lengths[i] + 3) & ~3;
    unsigned char *buf = new unsigned char[len];

    buf[len - 1] = 0x00;                /* assure padding with zeros */
    buf[len - 2] = 0x00;
    buf[len - 3] = 0x00;

    FT_Error error = FT_Load_Sfnt_Table(face, tags[i], 0, buf, NULL);
    if (error)
      programming_error ("FT_Load_Sfnt_Table (): error.");

    if (tag == head_tag)
      {
        /*
          first pass of computing the font checksum
          needs checkSumAdjustment = 0
         */
        buf[8] = 0x00;
        buf[9] = 0x00;
        buf[10] = 0x00;
        buf[11] = 0x00;
      }

    checksum = 0;
    unsigned char *endq = buf + len;
    for (unsigned char *q = buf; q < endq; q += 4)
      checksum += (q[0] << 24) | (q[1] << 16) | (q[2] << 8) | q[3];
    font_checksum += checksum;

    delete[] buf;

    *(p++) = (tags[i] & 0xFF000000UL) >> 24;
    *(p++) = (tags[i] & 0x00FF0000UL) >> 16;
    *(p++) = (tags[i] & 0x0000FF00UL) >> 8;
    *(p++) = tags[i] & 0x000000FFUL;

    *(p++) = (checksum & 0xFF000000UL) >> 24;
    *(p++) = (checksum & 0x00FF0000UL) >> 16;
    *(p++) = (checksum & 0x0000FF00UL) >> 8;
    *(p++) = checksum & 0x000000FFUL;

    *(p++) = (offset & 0xFF000000UL) >> 24;
    *(p++) = (offset & 0x00FF0000UL) >> 16;
    *(p++) = (offset & 0x0000FF00UL) >> 8;
    *(p++) = offset & 0x000000FFUL;

    *(p++) = (lengths[i] & 0xFF000000UL) >> 24;
    *(p++) = (lengths[i] & 0x00FF0000UL) >> 16;
    *(p++) = (lengths[i] & 0x0000FF00UL) >> 8;
    *(p++) = lengths[i] & 0x000000FFUL;

    /* offset must be a multiple of 4 */
    offset += (lengths[i] + 3) & ~3;
  }

  /* add checksum of TTF header */
  checksum = 0;
  for (unsigned char *q = hbuf; q < p; q += 4)
    checksum += (q[0] << 24) | (q[1] << 16) | (q[2] << 8) | q[3];
  font_checksum += checksum;
  font_checksum = 0xB1B0AFBAUL - font_checksum;

  /*
    see Adobe technical note 5012.Type42_Spec.pdf for details how
    the /sfnts array must be constructed
   */
  lily_cookie_fprintf (out, "/sfnts [");
  t42_write_table (out, face, hbuf, hlength, false,
                   head_length, loca_length);
  delete[] hbuf;

  idx = 0;

  while (FT_Sfnt_Table_Info(face, idx, &tag, &length)
         != FT_Err_Table_Missing)
    {
      unsigned char *buf = new unsigned char[length];
      FT_Error error = FT_Load_Sfnt_Table(face, tag, 0, buf, NULL);
      if (error)
        programming_error ("FT_Load_Sfnt_Table (): error.");

      if (tag == head_tag)
        {
          /* in the second pass simply store the computed font checksum */
          buf[8] = (font_checksum & 0xFF000000UL) >> 24;
          buf[9] = (font_checksum & 0x00FF0000UL) >> 16;
          buf[10] = (font_checksum & 0x0000FF00UL) >> 8;
          buf[11] = font_checksum & 0x000000FFUL;
        }

      bool is_glyf_table = tag == glyf_tag && length > CHUNKSIZE;
      t42_write_table (out, face, buf, length, is_glyf_table,
                       head_length, loca_length);

      delete[] buf;
      idx ++;
    }
  lily_cookie_fprintf (out, "\n] def\n");
}

static void
print_trailer (void *out,
               FT_Face face)
{
  const int GLYPH_NAME_LEN = 256;
  char glyph_name[GLYPH_NAME_LEN];

  TT_MaxProfile *mp
    = (TT_MaxProfile *)FT_Get_Sfnt_Table (face, ft_sfnt_maxp);

  lily_cookie_fprintf (out, "/CharStrings %d dict dup begin\n", mp->numGlyphs);

  Index_to_charcode_map ic_map (make_index_to_charcode_map (face));

  int output_count = 0;
  for (int i = 0; i < mp->numGlyphs; i++)
    {
      glyph_name[0] = 0;
      if (face->face_flags & FT_FACE_FLAG_GLYPH_NAMES)
        {
          FT_Error error = FT_Get_Glyph_Name (face, i, glyph_name,
                                              GLYPH_NAME_LEN);
          if (error)
            {
              programming_error ("FT_Get_Glyph_Name (): error.");
              glyph_name[0] = 0;
            }
        }

      if (!glyph_name[0] && ic_map.find (i) != ic_map.end ())
        {
          FT_ULong ucode = ic_map[i];
          get_unicode_name (glyph_name, ucode);
        }

      if (i == 0)
        sprintf (glyph_name, ".notdef");
      else if (glyph_name == string (".notdef"))
        glyph_name[0] = '\0';

      if (!glyph_name[0])
        get_glyph_index_name (glyph_name, i);

      if (glyph_name[0])
        {
          lily_cookie_fprintf (out, "/%s %d def ", glyph_name, i);
          output_count ++;
        }
      else
        programming_error (to_string ("no name for glyph %d", i));
                        
      if (! (output_count % 5))
        lily_cookie_fprintf (out, "\n");
    }

  lily_cookie_fprintf (out, "end readonly def\n");
  lily_cookie_fprintf (out, "FontName currentdict end definefont pop\n");
}

static void
create_type42_font (void *out, string name)
{
  FT_Face face = open_ft_face (name);

  print_header (out, face);
  print_body (out, face);
  print_trailer (out, face);

  FT_Done_Face (face);
}


LY_DEFINE (ly_ttf_ps_name, "ly:ttf-ps-name",
           1, 0, 0, (SCM ttf_file_name),
           "Extract the PostScript name from a TrueType font.")
{
  LY_ASSERT_TYPE (scm_is_string, ttf_file_name, 1);
  string file_name = ly_scm2string (ttf_file_name);
  if (be_verbose_global)
    progress_indication ("[" + file_name);

  FT_Face face = open_ft_face (file_name);
  char const *ps_name_str0 = FT_Get_Postscript_Name (face);
  SCM ps_name = scm_from_locale_string (ps_name_str0 ? ps_name_str0 : "");

  FT_Done_Face (face);

  if (be_verbose_global)
    progress_indication ("]");

  return ps_name;
}



LY_DEFINE (ly_ttf_2_pfa, "ly:ttf->pfa",
           1, 0, 0, (SCM ttf_file_name),
           "Convert the contents of a TTF file to Type42 PFA, returning it as "
           " a string.")
{
  LY_ASSERT_TYPE (scm_is_string, ttf_file_name, 1);

  string file_name = ly_scm2string (ttf_file_name);
  if (be_verbose_global)
    progress_indication ("[" + file_name);

  Memory_out_stream stream;

  create_type42_font (&stream, file_name);
  SCM asscm = scm_from_locale_stringn (stream.get_string (),
                                       stream.get_length ());

  if (be_verbose_global)
    progress_indication ("]");

  return asscm;
}