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