lily/tfm-reader.cc

   1 /*
   2   tfm-reader.cc --  implement Tex_font_metric_reader
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1999--2000 Jan Nieuwenhuizen <janneke@gnu.org>
   7
   8
   9   some code shamelessly copied from GNU fontutils-0.6/tfm/tfm_input.c
  10  */
  11
  12 #include "tfm-reader.hh"
  13 #include "string-convert.hh"
  14 #include "debug.hh"
  15 #include "warn.hh"
  16
  17 #define format_str String_convert::form_str
  18 #define FIX_UNITY (1 << 20)
  19 static const Real fix_to_real (Fix f);
  20
  21
  22 Tex_font_metric_reader::Tex_font_metric_reader (Tex_font_metric* fp, String name)
  23   : input_ (name)
  24 {
  25   tfm_l_=fp;
  26   tfm_l_->clear (TFM_SIZE);
  27   read_header ();
  28   read_params ();
  29   read_char_metrics ();
  30
  31 }
  32
  33 Tex_font_metric *
  34 Tex_font_metric_reader::read_file (String name)
  35 {
  36   Tex_font_metric * tfmp = new Tex_font_metric;
  37   Tex_font_metric_reader tfm_reader (tfmp, name);
  38
  39   return tfmp;
  40 }
  41
  42
  43
  44
  45 static const Real
  46 fix_to_real (Fix f)
  47 {
  48   Real r = f / FIX_UNITY + ((Real) (f % FIX_UNITY) / (Real) FIX_UNITY);
  49   return r;
  50 }
  51
  52 /* Most quantities are fixed-point fractions.  */
  53
  54 Real
  55 Tex_font_metric_reader::get_U32_fix_f ()
  56 {
  57   return fix_to_real (input_.get_U32 ());
  58 }
  59
  60 /* Dimensions are a `Fix' scaled by the design size.  */
  61
  62 Real
  63 Tex_font_metric_reader::get_U32_fix_scaled_f ()
  64 {
  65   return get_U32_fix_f () * tfm_l_->info_.design_size;
  66 }
  67
  68 String
  69 Tex_font_metric_reader::get_bcpl_str ()
  70 {
  71   U8 length_u8 = input_.get_U8 ();
  72   String str = input_.get_str (length_u8);
  73   return str;
  74 }
  75
  76 /* Here we read the information at the beginning of the file.  We store
  77    the result into the static variables `global_info' and
  78    `tfm_header'.  */
  79 void
  80 Tex_font_metric_reader::read_header ()
  81 {
  82   U16 file_length = input_.get_U16 ();
  83   (void) file_length;
  84   U16 header_length = input_.get_U16 ();
  85
  86   tfm_l_->info_.first_charcode = input_.get_U16 ();
  87   tfm_l_->info_.last_charcode = input_.get_U16 ();
  88   U16 width_word_count = input_.get_U16 ();
  89   U16 height_word_count = input_.get_U16 ();
  90   U16 depth_word_count = input_.get_U16 ();
  91   U16 italic_correction_word_count = input_.get_U16 ();
  92   U16 lig_kern_word_count = input_.get_U16 ();
  93   U16 kern_word_count = input_.get_U16 ();
  94   (void)kern_word_count;
  95   U16 extensible_word_count = input_.get_U16 ();
  96   (void)extensible_word_count;
  97
  98   tfm_l_->header_.param_word_count = input_.get_U16 ();
  99   tfm_l_->info_.parameter_count = tfm_l_->header_.param_word_count;
 100
 101   tfm_l_->header_.char_info_pos = (6 + header_length) * 4;
 102   tfm_l_->header_.width_pos = tfm_l_->header_.char_info_pos
 103                          + (tfm_l_->info_.last_charcode
 104                             - tfm_l_->info_.first_charcode + 1) * 4;
 105   tfm_l_->header_.height_pos = tfm_l_->header_.width_pos + width_word_count * 4;
 106   tfm_l_->header_.depth_pos = tfm_l_->header_.height_pos + height_word_count * 4;
 107   tfm_l_->header_.italic_correction_pos = tfm_l_->header_.depth_pos
 108                                      + depth_word_count * 4;
 109   tfm_l_->header_.lig_kern_pos = tfm_l_->header_.italic_correction_pos
 110     + italic_correction_word_count * 4;
 111   tfm_l_->header_.kern_pos = tfm_l_->header_.lig_kern_pos + lig_kern_word_count * 4;
 112   /* We don't care about the extensible table.  */
 113
 114   if (header_length < 2)
 115     error (_f ("TFM header of `%s' has only %u word(s)",
 116                input_.name_str ().ch_C (), header_length));
 117
 118   tfm_l_->info_.checksum = input_.get_U32 ();
 119   tfm_l_->info_.design_size = get_U32_fix_f ();
 120
 121   /* Although the coding scheme might be interesting to the caller, the
 122      font family and face byte probably aren't.  So we don't read them.  */
 123   tfm_l_->info_.coding_scheme = header_length > 2
 124     ? get_bcpl_str () : "unspecified";
 125
 126   DEBUG_OUT << format_str ("TFM checksum = %u, design_size = %fpt, coding scheme = `%s'.\n",
 127                       tfm_l_->info_.checksum,
 128                       tfm_l_->info_.design_size,
 129                       tfm_l_->info_.coding_scheme.ch_C ());
 130 }
 131
 132 /* Although TFM files are only usable by TeX if they have at least seven
 133    parameters, that is not a requirement of the file format itself, so
 134    we don't impose it.  And they can have many more than seven, of
 135    course.  We do impose a limit of TFM_MAX_FONT_PARAMETERS.  We assume
 136    that `tfm_header' has already been filled in.  */
 137
 138 void
 139 Tex_font_metric_reader::read_params ()
 140 {
 141   /* If we have no font parameters at all, we're done.  */
 142   if (tfm_l_->header_.param_word_count == 0)
 143     return;
 144
 145   //brrr
 146   /* Move to the beginning of the parameter table in the file.  */
 147   input_.seek_ch_C (-4 * tfm_l_->header_.param_word_count);
 148
 149   /* It's unlikely but possible that this TFM file has more fontdimens
 150      than we can deal with.  */
 151   if (tfm_l_->header_.param_word_count > TFM_MAX_FONTDIMENS)
 152     {
 153       warning (_f ("%s: TFM file has %u parameters, which is more than the %u I can handle",
 154                    input_.name_str ().ch_C (),
 155                    tfm_l_->header_.param_word_count,
 156                    TFM_MAX_FONTDIMENS));
 157       tfm_l_->header_.param_word_count = TFM_MAX_FONTDIMENS;
 158     }
 159
 160   /* The first parameter is different than all the rest, because it
 161      isn't scaled by the design size.  */
 162   tfm_l_->info_.parameters[(TFM_SLANT_PARAMETER) - 1] = get_U32_fix_f ();
 163
 164   for (Char_code i = 2; i <= tfm_l_->header_.param_word_count; i++)
 165     tfm_l_->info_.parameters[i - 1] = get_U32_fix_scaled_f ();
 166
 167 #ifdef PRINT
 168   for (Char_code i = 1; i <= tfm_l_->header_.param_word_count; i++)
 169     DEBUG_OUT << format_str ("TFM parameter %d: %.3f", i, tfm_l_->info_.parameters[i - 1]);
 170 #endif
 171 }
 172
 173 /* Read every character in the TFM file, storing the result in the
 174    static `tfm_char_table'.  We return a copy of that variable.  */
 175
 176 void
 177 Tex_font_metric_reader::read_char_metrics ()
 178 {
 179   for (int i = tfm_l_->info_.first_charcode; i <= tfm_l_->info_.last_charcode; i++)
 180     {
 181       Tex_font_char_metric tfm_char = read_char_metric (i);
 182       if (tfm_char.exists_b_)
 183         tfm_l_->ascii_to_metric_idx_[tfm_char.code_] = tfm_l_->char_metrics_.size ();
 184       tfm_l_->char_metrics_.push (tfm_char);
 185     }
 186 }
 187
 188 /* Read the character CODE.  If the character doesn't exist, return
 189    NULL.  If it does, save the information in `tfm_char_table', as well
 190    as returning it.  */
 191
 192 Tex_font_char_metric
 193 Tex_font_metric_reader::read_char_metric (Char_code code)
 194 {
 195   Tex_font_char_metric tfm_char;
 196
 197   /* If the character is outside the declared bounds in the file, don't
 198      try to read it. */
 199   if (code < tfm_l_->info_.first_charcode || code > tfm_l_->info_.last_charcode)
 200     return tfm_char;
 201
 202   //brr
 203   /* Move to the appropriate place in the `char_info' array.  */
 204   input_.seek_ch_C (tfm_l_->header_.char_info_pos + (code - tfm_l_->info_.first_charcode) * 4);
 205
 206   /* Read the character.  */
 207   tfm_char = read_char ();
 208
 209   if (tfm_char.exists_b_)
 210     tfm_char.code_ = code;
 211
 212   return tfm_char;
 213 }
 214
 215
 216 /* We assume we are positioned at the beginning of a `char_info' word.
 217    We read that word to get the indexes into the dimension tables; then
 218    we go read the tables to get the values (if the character exists).  */
 219
 220 Tex_font_char_metric
 221 Tex_font_metric_reader::read_char ()
 222 {
 223   /* Read the char_info word.  */
 224   U8 width_index = input_.get_U8 ();
 225
 226   U8 packed;
 227   packed = input_.get_U8 ();
 228   U8 height_index = (packed & 0xf0) >> 4;
 229   U8 depth_index = packed & 0x0f;
 230
 231   packed = input_.get_U8 ();
 232   U8 italic_correction_index = (packed & 0xfc) >> 6;
 233   U8 tag = packed & 0x3;
 234
 235   U8 remainder = input_.get_U8 ();
 236
 237   Tex_font_char_metric tfm_char;
 238
 239 #define GET_CHAR_DIMEN(d) \
 240    if (d##_index != 0) \
 241      { \
 242        input_.seek_ch_C (tfm_l_->header_.##d##_pos + d##_index*4); \
 243        tfm_char.d##_fix_ = input_.get_U32 (); \
 244        tfm_char.d##_ = fix_to_real (tfm_char.d##_fix_) \
 245                       * tfm_l_->info_.design_size; \
 246      }
 247
 248   GET_CHAR_DIMEN (width);
 249   GET_CHAR_DIMEN (height);
 250   GET_CHAR_DIMEN (depth);
 251   GET_CHAR_DIMEN (italic_correction);
 252
 253   /* The other condition for a character existing is that it be between
 254      the first and last character codes given in the header.  We've
 255      already assumed that's true (or we couldn't be positioned at a
 256      `char_info_word').  */
 257   tfm_char.exists_b_ = width_index != 0;
 258
 259 #ifdef PRINT
 260   DEBUG_OUT << format_str ("   width = %f, height = %f, ",
 261                       tfm_char.width_, tfm_char.height_);
 262   DEBUG_OUT << format_str ("depth = %f, ic = %f.\n",
 263                       tfm_char.depth, tfm_char.italic_correction);
 264 #endif
 265
 266   if (tag == 1)
 267     {
 268       input_.seek_ch_C (tfm_l_->header_.lig_kern_pos + remainder * 4);
 269       read_lig_kern_program (&tfm_char.ligature_arr_, &tfm_char.kern_arr_);
 270     }
 271
 272   /* We don't handle the other tags.  */
 273   return tfm_char;
 274 }
 275
 276 /* Read a ligature/kern program at the current position, storing the
 277    result into *LIGATURE and *KERN.  We don't distinguish all the kinds
 278    of ligatures that Metafont can output.  */
 279
 280 #define STOP_FLAG 128
 281 #define KERN_FLAG 128
 282
 283 void
 284 Tex_font_metric_reader::read_lig_kern_program (Array <Tfm_ligature>* ligature_arr_p, Array <Tfm_kern>* kern_arr_p)
 285 {
 286   bool end_b;
 287
 288   do
 289     {
 290       end_b = input_.get_U8 () >= STOP_FLAG;
 291
 292       U8 next_char = input_.get_U8 ();
 293       bool kern_step_b = input_.get_U8 () >= KERN_FLAG;
 294       U8 remainder = input_.get_U8 ();
 295
 296 #ifdef PRINT
 297       DEBUG_OUT << format_str ("   if next = %u (%c), ", next_char, next_char);
 298 #endif
 299
 300       if (kern_step_b)
 301         {
 302           Tfm_kern kern_element;
 303           kern_element.character = next_char;
 304
 305           char const* old_pos = input_.pos_ch_C ();
 306           input_.seek_ch_C (tfm_l_->header_.kern_pos + remainder * 4);
 307           kern_element.kern = get_U32_fix_scaled_f ();
 308           input_.set_pos (old_pos);
 309
 310           kern_arr_p->push (kern_element);
 311
 312 #ifdef PRINT
 313           DEBUG_OUT << format_str ("kern %f.\n", kern_element.kern);
 314 #endif
 315         }
 316       else
 317         {
 318           Tfm_ligature ligature_element;
 319           ligature_element.character = next_char;
 320           ligature_element.ligature = remainder;
 321           ligature_arr_p->push (ligature_element);
 322
 323 #ifdef PRINT
 324           DEBUG_OUT format_str ("ligature %d (hex %x).\n",
 325                            ligature_element.ligature,
 326                            ligature_element.ligature);
 327 #endif
 328         }
 329   } while (!end_b);
 330 }
 331