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-private.hh"
  28
  29 #include "hb-buffer-private.hh"
  30
  31 #include "hb-ot-layout.h"
  32
  33 /* XXX vertical */
  34 hb_tag_t default_features[] = {
  35   HB_TAG('c','a','l','t'),
  36   HB_TAG('c','c','m','p'),
  37   HB_TAG('c','l','i','g'),
  38   HB_TAG('c','s','w','h'),
  39   HB_TAG('c','u','r','s'),
  40   HB_TAG('k','e','r','n'),
  41   HB_TAG('l','i','g','a'),
  42   HB_TAG('l','o','c','l'),
  43   HB_TAG('m','a','r','k'),
  44   HB_TAG('m','k','m','k'),
  45   HB_TAG('r','l','i','g')
  46 };
  47
  48 enum {
  49   MASK_ALWAYS_ON = 1 << 0,
  50   MASK_RTLM      = 1 << 1
  51 };
  52 #define MASK_BITS_USED 2
  53
  54 struct lookup_map {
  55   unsigned int index;
  56   hb_mask_t mask;
  57 };
  58
  59
  60 static void
  61 add_feature (hb_face_t    *face,
  62              hb_tag_t      table_tag,
  63              unsigned int  feature_index,
  64              hb_mask_t     mask,
  65              lookup_map   *lookups,
  66              unsigned int *num_lookups,
  67              unsigned int  room_lookups)
  68 {
  69   unsigned int i = room_lookups - *num_lookups;
  70   lookups += *num_lookups;
  71
  72   unsigned int *lookup_indices = (unsigned int *) lookups;
  73
  74   hb_ot_layout_feature_get_lookup_indexes (face, table_tag, feature_index, 0,
  75                                            &i,
  76                                            lookup_indices);
  77
  78   *num_lookups += i;
  79
  80   while (i--) {
  81     lookups[i].mask = mask;
  82     lookups[i].index = lookup_indices[i];
  83   }
  84 }
  85
  86 static hb_bool_t
  87 maybe_add_feature (hb_face_t    *face,
  88                    hb_tag_t      table_tag,
  89                    unsigned int  script_index,
  90                    unsigned int  language_index,
  91                    hb_tag_t      feature_tag,
  92                    hb_mask_t     mask,
  93                    lookup_map   *lookups,
  94                    unsigned int *num_lookups,
  95                    unsigned int  room_lookups)
  96 {
  97   unsigned int feature_index;
  98   if (hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
  99                                           feature_tag,
 100                                           &feature_index))
 101   {
 102     add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups);
 103     return TRUE;
 104   }
 105   return FALSE;
 106 }
 107
 108 static int
 109 cmp_lookups (const void *p1, const void *p2)
 110 {
 111   const lookup_map *a = (const lookup_map *) p1;
 112   const lookup_map *b = (const lookup_map *) p2;
 113
 114   return a->index - b->index;
 115 }
 116
 117 static void
 118 setup_lookups (hb_face_t    *face,
 119                hb_buffer_t  *buffer,
 120                hb_feature_t *features,
 121                unsigned int  num_features,
 122                hb_tag_t      table_tag,
 123                lookup_map   *lookups,
 124                unsigned int *num_lookups,
 125                hb_direction_t original_direction)
 126 {
 127   unsigned int i, j, script_index, language_index, feature_index, room_lookups;
 128
 129   room_lookups = *num_lookups;
 130   *num_lookups = 0;
 131
 132   hb_ot_layout_table_choose_script (face, table_tag,
 133                                     hb_ot_tags_from_script (buffer->script),
 134                                     &script_index);
 135   hb_ot_layout_script_find_language (face, table_tag, script_index,
 136                                      hb_ot_tag_from_language (buffer->language),
 137                                      &language_index);
 138
 139   if (hb_ot_layout_language_get_required_feature_index (face, table_tag, script_index, language_index,
 140                                                         &feature_index))
 141     add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
 142
 143   for (i = 0; i < ARRAY_LENGTH (default_features); i++)
 144     maybe_add_feature (face, table_tag, script_index, language_index, default_features[i], 1, lookups, num_lookups, room_lookups);
 145
 146   switch (original_direction) {
 147     case HB_DIRECTION_LTR:
 148       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','a'), 1, lookups, num_lookups, room_lookups);
 149       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','m'), 1, lookups, num_lookups, room_lookups);
 150       break;
 151     case HB_DIRECTION_RTL:
 152       maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('r','t','l','a'), 1, lookups, num_lookups, room_lookups);
 153       break;
 154     case HB_DIRECTION_TTB:
 155     case HB_DIRECTION_BTT:
 156     default:
 157       break;
 158   }
 159
 160   unsigned int next_bit = MASK_BITS_USED;
 161   hb_mask_t global_mask = 0;
 162   for (i = 0; i < num_features; i++)
 163   {
 164     hb_feature_t *feature = &features[i];
 165     if (!hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
 166                                              feature->tag,
 167                                              &feature_index))
 168       continue;
 169
 170     if (feature->value == 1 && feature->start == 0 && feature->end == (unsigned int) -1) {
 171       add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
 172       continue;
 173     }
 174
 175     /* Allocate bits for the features */
 176
 177     unsigned int bits_needed = _hb_bit_storage (feature->value);
 178     if (!bits_needed)
 179       continue; /* Feature disabled */
 180
 181     if (next_bit + bits_needed > 8 * sizeof (hb_mask_t))
 182       continue; /* Oh well... */
 183
 184     unsigned int mask = (1 << (next_bit + bits_needed)) - (1 << next_bit);
 185     unsigned int value = feature->value << next_bit;
 186     next_bit += bits_needed;
 187
 188     add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups);
 189
 190     if (feature->start == 0 && feature->end == (unsigned int) -1)
 191       global_mask |= value;
 192     else
 193       buffer->or_masks (mask, feature->start, feature->end);
 194   }
 195
 196   if (global_mask)
 197     buffer->or_masks (global_mask, 0, (unsigned int) -1);
 198
 199   qsort (lookups, *num_lookups, sizeof (lookups[0]), cmp_lookups);
 200
 201   if (*num_lookups)
 202   {
 203     for (i = 1, j = 0; i < *num_lookups; i++)
 204       if (lookups[i].index != lookups[j].index)
 205         lookups[++j] = lookups[i];
 206       else
 207         lookups[j].mask |= lookups[i].mask;
 208     j++;
 209     *num_lookups = j;
 210   }
 211 }
 212
 213
 214 static hb_bool_t
 215 hb_ot_substitute_complex (hb_font_t    *font HB_UNUSED,
 216                           hb_face_t    *face,
 217                           hb_buffer_t  *buffer,
 218                           hb_feature_t *features,
 219                           unsigned int  num_features,
 220                           hb_direction_t original_direction)
 221 {
 222   lookup_map lookups[1000];
 223   unsigned int num_lookups = ARRAY_LENGTH (lookups);
 224   unsigned int i;
 225
 226   if (!hb_ot_layout_has_substitution (face))
 227     return FALSE;
 228
 229   setup_lookups (face, buffer, features, num_features,
 230                  HB_OT_TAG_GSUB,
 231                  lookups, &num_lookups,
 232                  original_direction);
 233
 234   for (i = 0; i < num_lookups; i++)
 235     hb_ot_layout_substitute_lookup (face, buffer, lookups[i].index, lookups[i].mask);
 236
 237   return TRUE;
 238 }
 239
 240 static hb_bool_t
 241 hb_ot_position_complex (hb_font_t    *font,
 242                         hb_face_t    *face,
 243                         hb_buffer_t  *buffer,
 244                         hb_feature_t *features,
 245                         unsigned int  num_features,
 246                         hb_direction_t original_direction)
 247 {
 248   lookup_map lookups[1000];
 249   unsigned int num_lookups = ARRAY_LENGTH (lookups);
 250   unsigned int i;
 251
 252   if (!hb_ot_layout_has_positioning (face))
 253     return FALSE;
 254
 255   setup_lookups (face, buffer, features, num_features,
 256                  HB_OT_TAG_GPOS,
 257                  lookups, &num_lookups,
 258                  original_direction);
 259
 260   for (i = 0; i < num_lookups; i++)
 261     hb_ot_layout_position_lookup (font, face, buffer, lookups[i].index, lookups[i].mask);
 262
 263   hb_ot_layout_position_finish (font, face, buffer);
 264
 265   return TRUE;
 266 }
 267
 268
 269 /* Main shaper */
 270
 271 /* Prepare */
 272
 273 static inline hb_bool_t
 274 is_variation_selector (hb_codepoint_t unicode)
 275 {
 276   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
 277                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
 278                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
 279 }
 280
 281 static void
 282 hb_form_clusters (hb_buffer_t *buffer)
 283 {
 284   unsigned int count = buffer->len;
 285   for (unsigned int i = 1; i < count; i++)
 286     if (buffer->unicode->v.get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
 287       buffer->info[i].cluster = buffer->info[i - 1].cluster;
 288 }
 289
 290 static hb_direction_t
 291 hb_ensure_native_direction (hb_buffer_t *buffer)
 292 {
 293   hb_direction_t original_direction = buffer->direction;
 294
 295   /* TODO vertical */
 296   if (HB_DIRECTION_IS_HORIZONTAL (original_direction) &&
 297       original_direction != _hb_script_get_horizontal_direction (buffer->script))
 298   {
 299     hb_buffer_reverse_clusters (buffer);
 300     buffer->direction = HB_DIRECTION_REVERSE (buffer->direction);
 301   }
 302
 303   return original_direction;
 304 }
 305
 306
 307 /* Substitute */
 308
 309 static void
 310 hb_mirror_chars (hb_buffer_t *buffer)
 311 {
 312   hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->v.get_mirroring;
 313
 314   if (HB_DIRECTION_IS_FORWARD (buffer->direction))
 315     return;
 316
 317   unsigned int count = buffer->len;
 318   for (unsigned int i = 0; i < count; i++) {
 319     hb_codepoint_t codepoint = get_mirroring (buffer->info[i].codepoint);
 320     if (likely (codepoint == buffer->info[i].codepoint))
 321       buffer->info[i].mask |= MASK_RTLM;
 322     else
 323       buffer->info[i].codepoint = codepoint;
 324   }
 325 }
 326
 327 static void
 328 hb_map_glyphs (hb_font_t    *font,
 329                hb_face_t    *face,
 330                hb_buffer_t  *buffer)
 331 {
 332   if (unlikely (!buffer->len))
 333     return;
 334
 335   unsigned int count = buffer->len - 1;
 336   for (unsigned int i = 0; i < count; i++) {
 337     if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) {
 338       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint);
 339       i++;
 340     } else {
 341       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0);
 342     }
 343   }
 344   buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0);
 345 }
 346
 347 static void
 348 hb_substitute_default (hb_font_t    *font,
 349                        hb_face_t    *face,
 350                        hb_buffer_t  *buffer,
 351                        hb_feature_t *features HB_UNUSED,
 352                        unsigned int  num_features HB_UNUSED)
 353 {
 354   hb_map_glyphs (font, face, buffer);
 355 }
 356
 357 static void
 358 hb_substitute_complex_fallback (hb_font_t    *font HB_UNUSED,
 359                                 hb_face_t    *face HB_UNUSED,
 360                                 hb_buffer_t  *buffer HB_UNUSED,
 361                                 hb_feature_t *features HB_UNUSED,
 362                                 unsigned int  num_features HB_UNUSED)
 363 {
 364   /* TODO Arabic */
 365 }
 366
 367
 368 /* Position */
 369
 370 static void
 371 hb_position_default (hb_font_t    *font,
 372                      hb_face_t    *face,
 373                      hb_buffer_t  *buffer,
 374                      hb_feature_t *features HB_UNUSED,
 375                      unsigned int  num_features HB_UNUSED)
 376 {
 377   hb_buffer_clear_positions (buffer);
 378
 379   unsigned int count = buffer->len;
 380   for (unsigned int i = 0; i < count; i++) {
 381     hb_glyph_metrics_t metrics;
 382     hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics);
 383     buffer->pos[i].x_advance = metrics.x_advance;
 384     buffer->pos[i].y_advance = metrics.y_advance;
 385   }
 386 }
 387
 388 static void
 389 hb_position_complex_fallback (hb_font_t    *font HB_UNUSED,
 390                               hb_face_t    *face HB_UNUSED,
 391                               hb_buffer_t  *buffer HB_UNUSED,
 392                               hb_feature_t *features HB_UNUSED,
 393                               unsigned int  num_features HB_UNUSED)
 394 {
 395   /* TODO Mark pos */
 396 }
 397
 398 static void
 399 hb_truetype_kern (hb_font_t    *font,
 400                   hb_face_t    *face,
 401                   hb_buffer_t  *buffer,
 402                   hb_feature_t *features HB_UNUSED,
 403                   unsigned int  num_features HB_UNUSED)
 404 {
 405   /* TODO Check for kern=0 */
 406   unsigned int count = buffer->len;
 407   for (unsigned int i = 1; i < count; i++) {
 408     hb_position_t kern, kern1, kern2;
 409     kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint);
 410     kern1 = kern >> 1;
 411     kern2 = kern - kern1;
 412     buffer->pos[i - 1].x_advance += kern1;
 413     buffer->pos[i].x_advance += kern2;
 414     buffer->pos[i].x_offset += kern2;
 415   }
 416 }
 417
 418 static void
 419 hb_position_complex_fallback_visual (hb_font_t    *font,
 420                                      hb_face_t    *face,
 421                                      hb_buffer_t  *buffer,
 422                                      hb_feature_t *features,
 423                                      unsigned int  num_features)
 424 {
 425   hb_truetype_kern (font, face, buffer, features, num_features);
 426 }
 427
 428
 429 /* Do it! */
 430
 431 void
 432 hb_ot_shape (hb_font_t    *font,
 433              hb_face_t    *face,
 434              hb_buffer_t  *buffer,
 435              hb_feature_t *features,
 436              unsigned int  num_features)
 437 {
 438   hb_direction_t original_direction;
 439   hb_bool_t substitute_fallback, position_fallback;
 440
 441   hb_form_clusters (buffer);
 442
 443   /* SUBSTITUTE */
 444
 445   buffer->clear_masks ();
 446
 447   /* Mirroring needs to see the original direction */
 448   hb_mirror_chars (buffer);
 449
 450   original_direction = hb_ensure_native_direction (buffer);
 451
 452   hb_substitute_default (font, face, buffer, features, num_features);
 453
 454   substitute_fallback = !hb_ot_substitute_complex (font, face, buffer, features, num_features, original_direction);
 455
 456   if (substitute_fallback)
 457     hb_substitute_complex_fallback (font, face, buffer, features, num_features);
 458
 459
 460   /* POSITION */
 461
 462   buffer->clear_masks ();
 463
 464   hb_position_default (font, face, buffer, features, num_features);
 465
 466   position_fallback = !hb_ot_position_complex (font, face, buffer, features, num_features, original_direction);
 467
 468   if (position_fallback)
 469     hb_position_complex_fallback (font, face, buffer, features, num_features);
 470
 471   if (HB_DIRECTION_IS_BACKWARD (buffer->direction))
 472     hb_buffer_reverse (buffer);
 473
 474   if (position_fallback)
 475     hb_position_complex_fallback_visual (font, face, buffer, features, num_features);
 476
 477   buffer->direction = original_direction;
 478 }