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) == 0x0E00u)
  39   {
  40     if (unlikely (klass == 0))
  41     {
  42       switch (u)
  43       {
  44         case 0x0E31u:
  45         case 0x0E34u:
  46         case 0x0E35u:
  47         case 0x0E36u:
  48         case 0x0E37u:
  49         case 0x0E47u:
  50         case 0x0E4Cu:
  51         case 0x0E4Du:
  52         case 0x0E4Eu:
  53           klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
  54           break;
  55
  56         case 0x0EB1u:
  57         case 0x0EB4u:
  58         case 0x0EB5u:
  59         case 0x0EB6u:
  60         case 0x0EB7u:
  61         case 0x0EBBu:
  62         case 0x0ECCu:
  63         case 0x0ECDu:
  64           klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
  65           break;
  66
  67         case 0x0EBCu:
  68           klass = HB_UNICODE_COMBINING_CLASS_BELOW;
  69           break;
  70       }
  71     } else {
  72       /* Thai virama is below-right */
  73       if (u == 0x0E3Au)
  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   hb_glyph_info_t *info = buffer->info;
 171   for (unsigned int i = 0; i < count; i++)
 172     if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
 173       unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
 174       combining_class = recategorize_combining_class (info[i].codepoint, combining_class);
 175       _hb_glyph_info_set_modified_combining_class (&info[i], combining_class);
 176     }
 177 }
 178
 179
 180 static void
 181 zero_mark_advances (hb_buffer_t *buffer,
 182                     unsigned int start,
 183                     unsigned int end)
 184 {
 185   hb_glyph_info_t *info = buffer->info;
 186   for (unsigned int i = start; i < end; i++)
 187     if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 188     {
 189       buffer->pos[i].x_advance = 0;
 190       buffer->pos[i].y_advance = 0;
 191     }
 192 }
 193
 194 static inline void
 195 position_mark (const hb_ot_shape_plan_t *plan,
 196                hb_font_t *font,
 197                hb_buffer_t  *buffer,
 198                hb_glyph_extents_t &base_extents,
 199                unsigned int i,
 200                unsigned int combining_class)
 201 {
 202   hb_glyph_extents_t mark_extents;
 203   if (!font->get_glyph_extents (buffer->info[i].codepoint,
 204                                 &mark_extents))
 205     return;
 206
 207   hb_position_t y_gap = font->y_scale / 16;
 208
 209   hb_glyph_position_t &pos = buffer->pos[i];
 210   pos.x_offset = pos.y_offset = 0;
 211
 212
 213   /* We dont position LEFT and RIGHT marks. */
 214
 215   /* X positioning */
 216   switch (combining_class)
 217   {
 218     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
 219     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
 220       if (buffer->props.direction == HB_DIRECTION_LTR) {
 221         pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
 222         break;
 223       } else if (buffer->props.direction == HB_DIRECTION_RTL) {
 224         pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
 225         break;
 226       }
 227       /* Fall through */
 228
 229     default:
 230     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
 231     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
 232     case HB_UNICODE_COMBINING_CLASS_BELOW:
 233     case HB_UNICODE_COMBINING_CLASS_ABOVE:
 234       /* Center align. */
 235       pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
 236       break;
 237
 238     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
 239     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
 240     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
 241       /* Left align. */
 242       pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
 243       break;
 244
 245     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
 246     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
 247     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
 248       /* Right align. */
 249       pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
 250       break;
 251   }
 252
 253   /* Y positioning */
 254   switch (combining_class)
 255   {
 256     case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
 257     case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
 258     case HB_UNICODE_COMBINING_CLASS_BELOW:
 259     case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
 260       /* Add gap, fall-through. */
 261       base_extents.height -= y_gap;
 262
 263     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
 264     case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
 265       pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
 266       /* Never shift up "below" marks. */
 267       if ((y_gap > 0) == (pos.y_offset > 0))
 268       {
 269         base_extents.height -= pos.y_offset;
 270         pos.y_offset = 0;
 271       }
 272       base_extents.height += mark_extents.height;
 273       break;
 274
 275     case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
 276     case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
 277     case HB_UNICODE_COMBINING_CLASS_ABOVE:
 278     case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
 279       /* Add gap, fall-through. */
 280       base_extents.y_bearing += y_gap;
 281       base_extents.height -= y_gap;
 282
 283     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
 284     case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
 285       pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
 286       /* Don't shift down "above" marks too much. */
 287       if ((y_gap > 0) != (pos.y_offset > 0))
 288       {
 289         unsigned int correction = -pos.y_offset / 2;
 290         base_extents.y_bearing += correction;
 291         base_extents.height -= correction;
 292         pos.y_offset += correction;
 293       }
 294       base_extents.y_bearing -= mark_extents.height;
 295       base_extents.height += mark_extents.height;
 296       break;
 297   }
 298 }
 299
 300 static inline void
 301 position_around_base (const hb_ot_shape_plan_t *plan,
 302                       hb_font_t *font,
 303                       hb_buffer_t  *buffer,
 304                       unsigned int base,
 305                       unsigned int end)
 306 {
 307   hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
 308   hb_glyph_extents_t base_extents;
 309   if (!font->get_glyph_extents (buffer->info[base].codepoint,
 310                                 &base_extents))
 311   {
 312     /* If extents don't work, zero marks and go home. */
 313     zero_mark_advances (buffer, base + 1, end);
 314     return;
 315   }
 316   base_extents.x_bearing += buffer->pos[base].x_offset;
 317   base_extents.y_bearing += buffer->pos[base].y_offset;
 318
 319   unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);
 320   unsigned int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);
 321
 322   hb_position_t x_offset = 0, y_offset = 0;
 323   if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
 324     x_offset -= buffer->pos[base].x_advance;
 325     y_offset -= buffer->pos[base].y_advance;
 326   }
 327
 328   hb_glyph_extents_t component_extents = base_extents;
 329   unsigned int last_lig_component = (unsigned int) -1;
 330   unsigned int last_combining_class = 255;
 331   hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */
 332   hb_glyph_info_t *info = buffer->info;
 333   for (unsigned int i = base + 1; i < end; i++)
 334     if (_hb_glyph_info_get_modified_combining_class (&info[i]))
 335     {
 336       if (num_lig_components > 1) {
 337         unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&info[i]);
 338         unsigned int this_lig_component = _hb_glyph_info_get_lig_comp (&info[i]) - 1;
 339         /* Conditions for attaching to the last component. */
 340         if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
 341           this_lig_component = num_lig_components - 1;
 342         if (last_lig_component != this_lig_component)
 343         {
 344           last_lig_component = this_lig_component;
 345           last_combining_class = 255;
 346           component_extents = base_extents;
 347           if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
 348             if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
 349               horiz_dir = plan->props.direction;
 350             else
 351               horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
 352           }
 353           if (horiz_dir == HB_DIRECTION_LTR)
 354             component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
 355           else
 356             component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
 357           component_extents.width /= num_lig_components;
 358         }
 359       }
 360
 361       unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
 362       if (last_combining_class != this_combining_class)
 363       {
 364         last_combining_class = this_combining_class;
 365         cluster_extents = component_extents;
 366       }
 367
 368       position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
 369
 370       buffer->pos[i].x_advance = 0;
 371       buffer->pos[i].y_advance = 0;
 372       buffer->pos[i].x_offset += x_offset;
 373       buffer->pos[i].y_offset += y_offset;
 374
 375     } else {
 376       if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
 377         x_offset -= buffer->pos[i].x_advance;
 378         y_offset -= buffer->pos[i].y_advance;
 379       } else {
 380         x_offset += buffer->pos[i].x_advance;
 381         y_offset += buffer->pos[i].y_advance;
 382       }
 383     }
 384 }
 385
 386 static inline void
 387 position_cluster (const hb_ot_shape_plan_t *plan,
 388                   hb_font_t *font,
 389                   hb_buffer_t  *buffer,
 390                   unsigned int start,
 391                   unsigned int end)
 392 {
 393   if (end - start < 2)
 394     return;
 395
 396   /* Find the base glyph */
 397   hb_glyph_info_t *info = buffer->info;
 398   for (unsigned int i = start; i < end; i++)
 399     if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))
 400     {
 401       /* Find mark glyphs */
 402       unsigned int j;
 403       for (j = i + 1; j < end; j++)
 404         if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[j])))
 405           break;
 406
 407       position_around_base (plan, font, buffer, i, j);
 408
 409       i = j - 1;
 410     }
 411 }
 412
 413 void
 414 _hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
 415                                 hb_font_t *font,
 416                                 hb_buffer_t  *buffer)
 417 {
 418   _hb_buffer_assert_gsubgpos_vars (buffer);
 419
 420   unsigned int start = 0;
 421   unsigned int last_cluster = buffer->info[0].cluster;
 422   unsigned int count = buffer->len;
 423   for (unsigned int i = 1; i < count; i++)
 424     if (buffer->info[i].cluster != last_cluster) {
 425       position_cluster (plan, font, buffer, start, i);
 426       start = i;
 427       last_cluster = buffer->info[i].cluster;
 428     }
 429   position_cluster (plan, font, buffer, start, count);
 430 }
 431
 432
 433 /* Performs old-style TrueType kerning. */
 434 void
 435 _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
 436                             hb_font_t *font,
 437                             hb_buffer_t  *buffer)
 438 {
 439   if (!plan->has_kern) return;
 440
 441   OT::hb_apply_context_t c (1, font, buffer);
 442   c.set_lookup_mask (plan->kern_mask);
 443   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
 444   OT::hb_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;
 445   skippy_iter.init (&c);
 446
 447   unsigned int count = buffer->len;
 448   hb_glyph_info_t *info = buffer->info;
 449   hb_glyph_position_t *pos = buffer->pos;
 450   for (unsigned int idx = 0; idx < count;)
 451   {
 452     skippy_iter.reset (idx, 1);
 453     if (!skippy_iter.next ())
 454     {
 455       idx++;
 456       continue;
 457     }
 458
 459     hb_position_t x_kern, y_kern;
 460     font->get_glyph_kerning_for_direction (info[idx].codepoint,
 461                                            info[skippy_iter.idx].codepoint,
 462                                            buffer->props.direction,
 463                                            &x_kern, &y_kern);
 464
 465     if (x_kern)
 466     {
 467       hb_position_t kern1 = x_kern >> 1;
 468       hb_position_t kern2 = x_kern - kern1;
 469       pos[idx].x_advance += kern1;
 470       pos[skippy_iter.idx].x_advance += kern2;
 471       pos[skippy_iter.idx].x_offset += kern2;
 472     }
 473
 474     if (y_kern)
 475     {
 476       hb_position_t kern1 = y_kern >> 1;
 477       hb_position_t kern2 = y_kern - kern1;
 478       pos[idx].y_advance += kern1;
 479       pos[skippy_iter.idx].y_advance += kern2;
 480       pos[skippy_iter.idx].y_offset += kern2;
 481     }
 482
 483     idx = skippy_iter.idx;
 484   }
 485 }