src/hb-ot-shape.cc

   1 /*
   2  * Copyright (C) 2009  Red Hat, Inc.
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  *
  24  * Red Hat Author(s): Behdad Esfahbod
  25  */
  26
  27 #include "hb-ot-shape.h"
  28
  29 #include "hb-buffer-private.hh"
  30
  31 #include "hb-ot-layout.h"
  32
  33 hb_tag_t default_features[] = {
  34   /* GSUB */
  35   HB_TAG('c','c','m','p'),
  36   HB_TAG('l','o','c','l'),
  37   HB_TAG('l','i','g','a'),
  38   HB_TAG('c','l','i','g'),
  39   /* GPOS */
  40   HB_TAG('k','e','r','n'),
  41   HB_TAG('m','a','r','k'),
  42   HB_TAG('m','k','m','k'),
  43 };
  44
  45 enum {
  46   MASK_ALWAYS_ON = 1 << 0,
  47   MASK_RTLM      = 1 << 1
  48 };
  49 #define MASK_BITS_USED 2
  50
  51 struct lookup_map {
  52   unsigned int index;
  53   hb_mask_t mask;
  54 };
  55
  56
  57 static void
  58 add_feature (hb_face_t    *face,
  59              hb_tag_t      table_tag,
  60              unsigned int  feature_index,
  61              hb_mask_t     mask,
  62              lookup_map   *lookups,
  63              unsigned int *num_lookups,
  64              unsigned int  room_lookups)
  65 {
  66   unsigned int i = room_lookups - *num_lookups;
  67   lookups += *num_lookups;
  68
  69   unsigned int *lookup_indices = (unsigned int *) lookups;
  70
  71   hb_ot_layout_feature_get_lookup_indexes (face, table_tag, feature_index, 0,
  72                                            &i,
  73                                            lookup_indices);
  74
  75   *num_lookups += i;
  76
  77   while (i--) {
  78     lookups[i].mask = mask;
  79     lookups[i].index = lookup_indices[i];
  80   }
  81 }
  82
  83 static hb_bool_t
  84 maybe_add_feature (hb_face_t    *face,
  85                    hb_tag_t      table_tag,
  86                    unsigned int  script_index,
  87                    unsigned int  language_index,
  88                    hb_tag_t      feature_tag,
  89                    hb_mask_t     mask,
  90                    lookup_map   *lookups,
  91                    unsigned int *num_lookups,
  92                    unsigned int  room_lookups)
  93 {
  94   unsigned int feature_index;
  95   if (hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
  96                                           feature_tag,
  97                                           &feature_index))
  98   {
  99     add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups);
 100     return TRUE;
 101   }
 102   return FALSE;
 103 }
 104
 105 static int
 106 cmp_lookups (const void *p1, const void *p2)
 107 {
 108   const lookup_map *a = (const lookup_map *) p1;
 109   const lookup_map *b = (const lookup_map *) p2;
 110
 111   return a->index - b->index;
 112 }
 113
 114 static void
 115 setup_lookups (hb_face_t    *face,
 116                hb_buffer_t  *buffer,
 117                hb_feature_t *features,
 118                unsigned int  num_features,
 119                hb_tag_t      table_tag,
 120                lookup_map   *lookups,
 121                unsigned int *num_lookups,
 122                hb_direction_t original_direction)
 123 {
 124   unsigned int i, j, script_index, language_index, feature_index, room_lookups;
 125
 126   room_lookups = *num_lookups;
 127   *num_lookups = 0;
 128
 129   hb_ot_layout_table_choose_script (face, table_tag,
 130                                     hb_ot_tags_from_script (buffer->script),
 131                                     &script_index);
 132   hb_ot_layout_script_find_language (face, table_tag, script_index,
 133                                      hb_ot_tag_from_language (buffer->language),
 134                                      &language_index);
 135
 136   if (hb_ot_layout_language_get_required_feature_index (face, table_tag, script_index, language_index,
 137                                                         &feature_index))
 138     add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
 139
 140   for (i = 0; i < ARRAY_LENGTH (default_features); i++)
 141     maybe_add_feature (face, table_tag, script_index, language_index, default_features[i], 1, lookups, num_lookups, room_lookups);
 142
 143   switch (original_direction) {
 144     case HB_DIRECTION_LTR:
 145       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','a'), 1, lookups, num_lookups, room_lookups);
 146       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','m'), 1, lookups, num_lookups, room_lookups);
 147       break;
 148     case HB_DIRECTION_RTL:
 149       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('r','t','l','a'), 1, lookups, num_lookups, room_lookups);
 150       break;
 151     case HB_DIRECTION_TTB:
 152     case HB_DIRECTION_BTT:
 153     default:
 154       break;
 155   }
 156
 157   unsigned int next_bit = MASK_BITS_USED;
 158   hb_mask_t global_mask = 0;
 159   for (i = 0; i < num_features; i++)
 160   {
 161     hb_feature_t *feature = &features[i];
 162     if (!hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
 163                                              feature->tag,
 164                                              &feature_index))
 165       continue;
 166
 167     if (feature->value == 1 && feature->start == 0 && feature->end == (unsigned int) -1) {
 168       add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
 169       continue;
 170     }
 171
 172     /* Allocate bits for the features */
 173
 174     unsigned int bits_needed = _hb_bit_storage (feature->value);
 175     if (!bits_needed)
 176       continue; /* Feature disabled */
 177
 178     if (next_bit + bits_needed > 8 * sizeof (hb_mask_t))
 179       continue; /* Oh well... */
 180
 181     unsigned int mask = (1 << (next_bit + bits_needed)) - (1 << next_bit);
 182     unsigned int value = feature->value << next_bit;
 183     next_bit += bits_needed;
 184
 185     add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups);
 186
 187     if (feature->start == 0 && feature->end == (unsigned int) -1)
 188       global_mask |= value;
 189     else
 190       buffer->or_masks (mask, feature->start, feature->end);
 191   }
 192
 193   if (global_mask)
 194     buffer->or_masks (global_mask, 0, (unsigned int) -1);
 195
 196   qsort (lookups, *num_lookups, sizeof (lookups[0]), cmp_lookups);
 197
 198   if (*num_lookups)
 199   {
 200     for (i = 1, j = 0; i < *num_lookups; i++)
 201       if (lookups[i].index != lookups[j].index)
 202         lookups[++j] = lookups[i];
 203       else
 204         lookups[j].mask |= lookups[i].mask;
 205     j++;
 206     *num_lookups = j;
 207   }
 208 }
 209
 210
 211 static hb_bool_t
 212 hb_ot_substitute_complex (hb_font_t    *font HB_UNUSED,
 213                           hb_face_t    *face,
 214                           hb_buffer_t  *buffer,
 215                           hb_feature_t *features,
 216                           unsigned int  num_features,
 217                           hb_direction_t original_direction)
 218 {
 219   lookup_map lookups[1000];
 220   unsigned int num_lookups = ARRAY_LENGTH (lookups);
 221   unsigned int i;
 222
 223   if (!hb_ot_layout_has_substitution (face))
 224     return FALSE;
 225
 226   setup_lookups (face, buffer, features, num_features,
 227                  HB_OT_TAG_GSUB,
 228                  lookups, &num_lookups,
 229                  original_direction);
 230
 231   for (i = 0; i < num_lookups; i++)
 232     hb_ot_layout_substitute_lookup (face, buffer, lookups[i].index, lookups[i].mask);
 233
 234   return TRUE;
 235 }
 236
 237 static hb_bool_t
 238 hb_ot_position_complex (hb_font_t    *font,
 239                         hb_face_t    *face,
 240                         hb_buffer_t  *buffer,
 241                         hb_feature_t *features,
 242                         unsigned int  num_features,
 243                         hb_direction_t original_direction)
 244 {
 245   lookup_map lookups[1000];
 246   unsigned int num_lookups = ARRAY_LENGTH (lookups);
 247   unsigned int i;
 248
 249   if (!hb_ot_layout_has_positioning (face))
 250     return FALSE;
 251
 252   setup_lookups (face, buffer, features, num_features,
 253                  HB_OT_TAG_GPOS,
 254                  lookups, &num_lookups,
 255                  original_direction);
 256
 257   for (i = 0; i < num_lookups; i++)
 258     hb_ot_layout_position_lookup (font, face, buffer, lookups[i].index, lookups[i].mask);
 259
 260   hb_ot_layout_position_finish (font, face, buffer);
 261
 262   return TRUE;
 263 }
 264
 265
 266 /* Main shaper */
 267
 268 /* Prepare */
 269
 270 static inline hb_bool_t
 271 is_variation_selector (hb_codepoint_t unicode)
 272 {
 273   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
 274                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
 275                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
 276 }
 277
 278 static void
 279 hb_form_clusters (hb_buffer_t *buffer)
 280 {
 281   unsigned int count = buffer->len;
 282   for (unsigned int i = 1; i < count; i++)
 283     if (buffer->unicode->get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
 284       buffer->info[i].cluster = buffer->info[i - 1].cluster;
 285 }
 286
 287 static hb_direction_t
 288 hb_ensure_native_direction (hb_buffer_t *buffer)
 289 {
 290   hb_direction_t original_direction = buffer->direction;
 291
 292   /* TODO vertical */
 293   if (HB_DIRECTION_IS_HORIZONTAL (original_direction) &&
 294       original_direction != _hb_script_get_horizontal_direction (buffer->script))
 295   {
 296     hb_buffer_reverse_clusters (buffer);
 297     buffer->direction = HB_DIRECTION_REVERSE (buffer->direction);
 298   }
 299
 300   return original_direction;
 301 }
 302
 303
 304 /* Substitute */
 305
 306 static void
 307 hb_mirror_chars (hb_buffer_t *buffer)
 308 {
 309   hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->get_mirroring;
 310
 311   if (HB_DIRECTION_IS_FORWARD (buffer->direction))
 312     return;
 313
 314   unsigned int count = buffer->len;
 315   for (unsigned int i = 0; i < count; i++) {
 316     hb_codepoint_t codepoint = get_mirroring (buffer->info[i].codepoint);
 317     if (likely (codepoint == buffer->info[i].codepoint))
 318       buffer->info[i].mask |= MASK_RTLM;
 319     else
 320       buffer->info[i].codepoint = codepoint;
 321   }
 322 }
 323
 324 static void
 325 hb_map_glyphs (hb_font_t    *font,
 326                hb_face_t    *face,
 327                hb_buffer_t  *buffer)
 328 {
 329   if (unlikely (!buffer->len))
 330     return;
 331
 332   unsigned int count = buffer->len - 1;
 333   for (unsigned int i = 0; i < count; i++) {
 334     if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) {
 335       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint);
 336       i++;
 337     } else {
 338       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0);
 339     }
 340   }
 341   buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0);
 342 }
 343
 344 static void
 345 hb_substitute_default (hb_font_t    *font,
 346                        hb_face_t    *face,
 347                        hb_buffer_t  *buffer,
 348                        hb_feature_t *features HB_UNUSED,
 349                        unsigned int  num_features HB_UNUSED)
 350 {
 351   hb_mirror_chars (buffer);
 352   hb_map_glyphs (font, face, buffer);
 353 }
 354
 355 static void
 356 hb_substitute_complex_fallback (hb_font_t    *font HB_UNUSED,
 357                                 hb_face_t    *face HB_UNUSED,
 358                                 hb_buffer_t  *buffer HB_UNUSED,
 359                                 hb_feature_t *features HB_UNUSED,
 360                                 unsigned int  num_features HB_UNUSED)
 361 {
 362   /* TODO Arabic */
 363 }
 364
 365
 366 /* Position */
 367
 368 static void
 369 hb_position_default (hb_font_t    *font,
 370                      hb_face_t    *face,
 371                      hb_buffer_t  *buffer,
 372                      hb_feature_t *features HB_UNUSED,
 373                      unsigned int  num_features HB_UNUSED)
 374 {
 375   hb_buffer_clear_positions (buffer);
 376
 377   unsigned int count = buffer->len;
 378   for (unsigned int i = 0; i < count; i++) {
 379     hb_glyph_metrics_t metrics;
 380     hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics);
 381     buffer->pos[i].x_advance = metrics.x_advance;
 382     buffer->pos[i].y_advance = metrics.y_advance;
 383   }
 384 }
 385
 386 static void
 387 hb_position_complex_fallback (hb_font_t    *font HB_UNUSED,
 388                               hb_face_t    *face HB_UNUSED,
 389                               hb_buffer_t  *buffer HB_UNUSED,
 390                               hb_feature_t *features HB_UNUSED,
 391                               unsigned int  num_features HB_UNUSED)
 392 {
 393   /* TODO Mark pos */
 394 }
 395
 396 static void
 397 hb_truetype_kern (hb_font_t    *font,
 398                   hb_face_t    *face,
 399                   hb_buffer_t  *buffer,
 400                   hb_feature_t *features HB_UNUSED,
 401                   unsigned int  num_features HB_UNUSED)
 402 {
 403   /* TODO Check for kern=0 */
 404   unsigned int count = buffer->len;
 405   for (unsigned int i = 1; i < count; i++) {
 406     hb_position_t kern, kern1, kern2;
 407     kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint);
 408     kern1 = kern >> 1;
 409     kern2 = kern - kern1;
 410     buffer->pos[i - 1].x_advance += kern1;
 411     buffer->pos[i].x_advance += kern2;
 412     buffer->pos[i].x_offset += kern2;
 413   }
 414 }
 415
 416 static void
 417 hb_position_complex_fallback_visual (hb_font_t    *font,
 418                                      hb_face_t    *face,
 419                                      hb_buffer_t  *buffer,
 420                                      hb_feature_t *features,
 421                                      unsigned int  num_features)
 422 {
 423   hb_truetype_kern (font, face, buffer, features, num_features);
 424 }
 425
 426
 427 /* Do it! */
 428
 429 void
 430 hb_ot_shape (hb_font_t    *font,
 431              hb_face_t    *face,
 432              hb_buffer_t  *buffer,
 433              hb_feature_t *features,
 434              unsigned int  num_features)
 435 {
 436   hb_direction_t original_direction;
 437   hb_bool_t substitute_fallback, position_fallback;
 438
 439   hb_form_clusters (buffer);
 440
 441   /* SUBSTITUTE */
 442
 443   buffer->clear_masks ();
 444
 445   hb_substitute_default (font, face, buffer, features, num_features);
 446
 447   /* We do this after substitute_default because mirroring needs to
 448    * see the original direction. */
 449   original_direction = hb_ensure_native_direction (buffer);
 450
 451   substitute_fallback = !hb_ot_substitute_complex (font, face, buffer, features, num_features, original_direction);
 452
 453   if (substitute_fallback)
 454     hb_substitute_complex_fallback (font, face, buffer, features, num_features);
 455
 456
 457   /* POSITION */
 458
 459   buffer->clear_masks ();
 460
 461   hb_position_default (font, face, buffer, features, num_features);
 462
 463   position_fallback = !hb_ot_position_complex (font, face, buffer, features, num_features, original_direction);
 464
 465   if (position_fallback)
 466     hb_position_complex_fallback (font, face, buffer, features, num_features);
 467
 468   if (HB_DIRECTION_IS_BACKWARD (buffer->direction))
 469     hb_buffer_reverse (buffer);
 470
 471   if (position_fallback)
 472     hb_position_complex_fallback_visual (font, face, buffer, features, num_features);
 473
 474   buffer->direction = original_direction;
 475 }