third_party/harfbuzz-ng/src/hb-ot-shape-fallback.cc

   1 /*
   2  * Copyright © 2011,2012  Google, 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  * Google Author(s): Behdad Esfahbod
  25  */
  26
  27 #include "hb-ot-shape-fallback-private.hh"
  28 #include "hb-ot-layout-gsubgpos-private.hh"
  29
  30 static unsigned int
  31 recategorize_combining_class (hb_codepoint_t u,
  32                               unsigned int klass)
  33 {
  34   if (klass >= 200)
  35     return klass;
  36
  37   /* Thai / Lao need some per-character work. */
  38   if ((u & ~0xFF) == 0x0E00)
  39   {
  40     if (unlikely (klass == 0))
  41     {
  42       switch (u)
  43       {
  44         case 0x0E31:
  45         case 0x0E34:
  46         case 0x0E35:
  47         case 0x0E36:
  48         case 0x0E37:
  49         case 0x0E47:
  50         case 0x0E4C:
  51         case 0x0E4D:
  52         case 0x0E4E:
  53           klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  54           break;
  55
  56         case 0x0EB1:
  57         case 0x0EB4:
  58         case 0x0EB5:
  59         case 0x0EB6:
  60         case 0x0EB7:
  61         case 0x0EBB:
  62         case 0x0ECC:
  63         case 0x0ECD:
  64           klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
  65           break;
  66
  67         case 0x0EBC:
  68           klass = HB_UNICODE_COMBINING_CLASS_BELOW;
  69           break;
  70       }
  71     } else {
  72       /* Thai virama is below-right */
  73       if (u == 0x0E3A)
  74         klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
  75     }
  76   }
  77
  78   switch (klass)
  79   {
  80
  81     /* Hebrew */
  82
  83     case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
  84     case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
  85     case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
  86     case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
  87     case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
  88     case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
  89     case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
  90     case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
  91     case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */
  92     case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
  93     case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
  94       return HB_UNICODE_COMBINING_CLASS_BELOW;
  95
  96     case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
  97       return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
  98
  99     case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
 100       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
 101
 102     case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
 103     case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */
 104       return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
 105
 106     case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
 107       return HB_UNICODE_COMBINING_CLASS_ABOVE;
 108
 109     case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
 110       break;
 111
 112
 113     /* Arabic and Syriac */
 114
 115     case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
 116     case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
 117     case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
 118     case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
 119     case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
 120     case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
 121     case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
 122     case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
 123       return HB_UNICODE_COMBINING_CLASS_ABOVE;
 124
 125     case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
 126     case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
 127       return HB_UNICODE_COMBINING_CLASS_BELOW;
 128
 129
 130     /* Thai */
 131
 132     case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
 133       return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
 134
 135     case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
 136       return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
 137
 138
 139     /* Lao */
 140
 141     case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
 142       return HB_UNICODE_COMBINING_CLASS_BELOW;
 143
 144     case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
 145       return HB_UNICODE_COMBINING_CLASS_ABOVE;
 146
 147
 148     /* Tibetan */
 149
 150     case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
 151       return HB_UNICODE_COMBINING_CLASS_BELOW;
 152
 153     case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
 154       return HB_UNICODE_COMBINING_CLASS_ABOVE;
 155
 156     case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
 157       return HB_UNICODE_COMBINING_CLASS_BELOW;
 158
 159   }
 160
 161   return klass;
 162 }
 163
 164 void
 165 _hb_ot_shape_fallback_position_recategorize_marks (const hb_ot_shape_plan_t *plan HB_UNUSED,
 166                                                    hb_font_t *font HB_UNUSED,
 167                                                    hb_buffer_t  *buffer)
 168 {
 169   unsigned int count = buffer->len;
 170   for (unsigned int i = 0; i < count; i++)
 171     if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
 172       unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
 173       combining_class = recategorize_combining_class (buffer->info[i].codepoint, combining_class);
 174       _hb_glyph_info_set_modified_combining_class (&buffer->info[i], combining_class);
 175     }
 176 }
 177
 178
 179 static void
 180 zero_mark_advances (hb_buffer_t *buffer,
 181                     unsigned int start,
 182                     unsigned int end)
 183 {
 184   for (unsigned int i = start; i < end; i++)
 185     if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 186     {
 187       buffer->pos[i].x_advance = 0;
 188       buffer->pos[i].y_advance = 0;
 189     }
 190 }
 191
 192 static inline void
 193 position_mark (const hb_ot_shape_plan_t *plan,
 194                hb_font_t *font,
 195                hb_buffer_t  *buffer,
 196                hb_glyph_extents_t &base_extents,
 197                unsigned int i,
 198                unsigned int combining_class)
 199 {
 200   hb_glyph_extents_t mark_extents;
 201   if (!font->get_glyph_extents (buffer->info[i].codepoint,
 202                                 &mark_extents))
 203     return;
 204
 205   hb_position_t y_gap = font->y_scale / 16;
 206
 207   hb_glyph_position_t &pos = buffer->pos[i];
 208   pos.x_offset = pos.y_offset = 0;
 209
 210
 211   /* We dont position LEFT and RIGHT marks. */
 212
 213   /* X positioning */
 214   switch (combining_class)
 215   {
 216     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
 217     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
 218       if (buffer->props.direction == HB_DIRECTION_LTR) {
 219         pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
 220         break;
 221       } else if (buffer->props.direction == HB_DIRECTION_RTL) {
 222         pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
 223         break;
 224       }
 225       /* Fall through */
 226
 227     default:
 228     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
 229     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
 230     case HB_UNICODE_COMBINING_CLASS_BELOW:
 231     case HB_UNICODE_COMBINING_CLASS_ABOVE:
 232       /* Center align. */
 233       pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
 234       break;
 235
 236     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
 237     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
 238     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
 239       /* Left align. */
 240       pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
 241       break;
 242
 243     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
 244     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
 245     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
 246       /* Right align. */
 247       pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
 248       break;
 249   }
 250
 251   /* Y positioning */
 252   switch (combining_class)
 253   {
 254     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
 255     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
 256     case HB_UNICODE_COMBINING_CLASS_BELOW:
 257     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
 258       /* Add gap, fall-through. */
 259       base_extents.height -= y_gap;
 260
 261     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
 262     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
 263       pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
 264       /* Never shift up "below" marks. */
 265       if ((y_gap > 0) == (pos.y_offset > 0))
 266       {
 267         base_extents.height -= pos.y_offset;
 268         pos.y_offset = 0;
 269       }
 270       base_extents.height += mark_extents.height;
 271       break;
 272
 273     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
 274     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
 275     case HB_UNICODE_COMBINING_CLASS_ABOVE:
 276     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
 277       /* Add gap, fall-through. */
 278       base_extents.y_bearing += y_gap;
 279       base_extents.height -= y_gap;
 280
 281     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
 282     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
 283       pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
 284       /* Don't shift down "above" marks too much. */
 285       if ((y_gap > 0) != (pos.y_offset > 0))
 286       {
 287         unsigned int correction = -pos.y_offset / 2;
 288         base_extents.y_bearing += correction;
 289         base_extents.height -= correction;
 290         pos.y_offset += correction;
 291       }
 292       base_extents.y_bearing -= mark_extents.height;
 293       base_extents.height += mark_extents.height;
 294       break;
 295   }
 296 }
 297
 298 static inline void
 299 position_around_base (const hb_ot_shape_plan_t *plan,
 300                       hb_font_t *font,
 301                       hb_buffer_t  *buffer,
 302                       unsigned int base,
 303                       unsigned int end)
 304 {
 305   hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
 306   hb_glyph_extents_t base_extents;
 307   if (!font->get_glyph_extents (buffer->info[base].codepoint,
 308                                 &base_extents))
 309   {
 310     /* If extents don't work, zero marks and go home. */
 311     zero_mark_advances (buffer, base + 1, end);
 312     return;
 313   }
 314   base_extents.x_bearing += buffer->pos[base].x_offset;
 315   base_extents.y_bearing += buffer->pos[base].y_offset;
 316
 317   unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);
 318   unsigned int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);
 319
 320   hb_position_t x_offset = 0, y_offset = 0;
 321   if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
 322     x_offset -= buffer->pos[base].x_advance;
 323     y_offset -= buffer->pos[base].y_advance;
 324   }
 325
 326   hb_glyph_extents_t component_extents = base_extents;
 327   unsigned int last_lig_component = (unsigned int) -1;
 328   unsigned int last_combining_class = 255;
 329   hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */
 330   for (unsigned int i = base + 1; i < end; i++)
 331     if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]))
 332     {
 333       if (num_lig_components > 1) {
 334         unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&buffer->info[i]);
 335         unsigned int this_lig_component = _hb_glyph_info_get_lig_comp (&buffer->info[i]) - 1;
 336         /* Conditions for attaching to the last component. */
 337         if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
 338           this_lig_component = num_lig_components - 1;
 339         if (last_lig_component != this_lig_component)
 340         {
 341           last_lig_component = this_lig_component;
 342           last_combining_class = 255;
 343           component_extents = base_extents;
 344           if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
 345             if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
 346               horiz_dir = plan->props.direction;
 347             else
 348               horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
 349           }
 350           if (horiz_dir == HB_DIRECTION_LTR)
 351             component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
 352           else
 353             component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
 354           component_extents.width /= num_lig_components;
 355         }
 356       }
 357
 358       unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
 359       if (last_combining_class != this_combining_class)
 360       {
 361         last_combining_class = this_combining_class;
 362         cluster_extents = component_extents;
 363       }
 364
 365       position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
 366
 367       buffer->pos[i].x_advance = 0;
 368       buffer->pos[i].y_advance = 0;
 369       buffer->pos[i].x_offset += x_offset;
 370       buffer->pos[i].y_offset += y_offset;
 371
 372     } else {
 373       if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
 374         x_offset -= buffer->pos[i].x_advance;
 375         y_offset -= buffer->pos[i].y_advance;
 376       } else {
 377         x_offset += buffer->pos[i].x_advance;
 378         y_offset += buffer->pos[i].y_advance;
 379       }
 380     }
 381 }
 382
 383 static inline void
 384 position_cluster (const hb_ot_shape_plan_t *plan,
 385                   hb_font_t *font,
 386                   hb_buffer_t  *buffer,
 387                   unsigned int start,
 388                   unsigned int end)
 389 {
 390   if (end - start < 2)
 391     return;
 392
 393   /* Find the base glyph */
 394   for (unsigned int i = start; i < end; i++)
 395     if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[i])))
 396     {
 397       /* Find mark glyphs */
 398       unsigned int j;
 399       for (j = i + 1; j < end; j++)
 400         if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[j])))
 401           break;
 402
 403       position_around_base (plan, font, buffer, i, j);
 404
 405       i = j - 1;
 406     }
 407 }
 408
 409 void
 410 _hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
 411                                 hb_font_t *font,
 412                                 hb_buffer_t  *buffer)
 413 {
 414   unsigned int start = 0;
 415   unsigned int last_cluster = buffer->info[0].cluster;
 416   unsigned int count = buffer->len;
 417   for (unsigned int i = 1; i < count; i++)
 418     if (buffer->info[i].cluster != last_cluster) {
 419       position_cluster (plan, font, buffer, start, i);
 420       start = i;
 421       last_cluster = buffer->info[i].cluster;
 422     }
 423   position_cluster (plan, font, buffer, start, count);
 424 }
 425
 426
 427 /* Performs old-style TrueType kerning. */
 428 void
 429 _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
 430                             hb_font_t *font,
 431                             hb_buffer_t  *buffer)
 432 {
 433   hb_mask_t kern_mask = plan->map.get_1_mask (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction) ?
 434                                               HB_TAG ('k','e','r','n') : HB_TAG ('v','k','r','n'));
 435   if (!kern_mask) return;
 436
 437   unsigned int count = buffer->len;
 438
 439   OT::hb_apply_context_t c (1, font, buffer);
 440   c.set_lookup_mask (kern_mask);
 441   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
 442
 443   hb_glyph_info_t *info = buffer->info;
 444   hb_glyph_position_t *pos = buffer->pos;
 445
 446   for (unsigned int idx = 0; idx < count;)
 447   {
 448     OT::hb_apply_context_t::skipping_forward_iterator_t skippy_iter (&c, idx, 1);
 449     if (!skippy_iter.next ())
 450     {
 451       idx++;
 452       continue;
 453     }
 454
 455     hb_position_t x_kern, y_kern;
 456     font->get_glyph_kerning_for_direction (info[idx].codepoint,
 457                                            info[skippy_iter.idx].codepoint,
 458                                            buffer->props.direction,
 459                                            &x_kern, &y_kern);
 460
 461     if (x_kern)
 462     {
 463       hb_position_t kern1 = x_kern >> 1;
 464       hb_position_t kern2 = x_kern - kern1;
 465       pos[idx].x_advance += kern1;
 466       pos[skippy_iter.idx].x_advance += kern2;
 467       pos[skippy_iter.idx].x_offset += kern2;
 468     }
 469
 470     if (y_kern)
 471     {
 472       hb_position_t kern1 = y_kern >> 1;
 473       hb_position_t kern2 = y_kern - kern1;
 474       pos[idx].y_advance += kern1;
 475       pos[skippy_iter.idx].y_advance += kern2;
 476       pos[skippy_iter.idx].y_offset += kern2;
 477     }
 478
 479     idx = skippy_iter.idx;
 480   }
 481 }