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