src/hb-ot-shape.cc

   1 /*
   2  * Copyright © 2009,2010  Red Hat, Inc.
   3  * Copyright © 2010,2011  Google, Inc.
   4  *
   5  *  This is part of HarfBuzz, a text shaping library.
   6  *
   7  * Permission is hereby granted, without written agreement and without
   8  * license or royalty fees, to use, copy, modify, and distribute this
   9  * software and its documentation for any purpose, provided that the
  10  * above copyright notice and the following two paragraphs appear in
  11  * all copies of this software.
  12  *
  13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  17  * DAMAGE.
  18  *
  19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  24  *
  25  * Red Hat Author(s): Behdad Esfahbod
  26  * Google Author(s): Behdad Esfahbod
  27  */
  28
  29 #include "hb-ot-shape-private.hh"
  30 #include "hb-ot-shape-complex-private.hh"
  31
  32 #include "hb-font-private.hh"
  33
  34 HB_BEGIN_DECLS
  35
  36
  37 hb_tag_t early_features[] = {
  38   HB_TAG('c','c','m','p'),
  39   HB_TAG('l','o','c','l'),
  40 };
  41
  42 hb_tag_t common_features[] = {
  43   HB_TAG('m','a','r','k'),
  44   HB_TAG('m','k','m','k'),
  45   HB_TAG('r','l','i','g'),
  46 };
  47
  48 hb_tag_t horizontal_features[] = {
  49   HB_TAG('c','a','l','t'),
  50   HB_TAG('c','l','i','g'),
  51   HB_TAG('c','u','r','s'),
  52   HB_TAG('k','e','r','n'),
  53   HB_TAG('l','i','g','a'),
  54 };
  55
  56 /* Note:
  57  * Technically speaking, vrt2 and vert are mutually exclusive.
  58  * According to the spec, valt and vpal are also mutually exclusive.
  59  * But we apply them all for now.
  60  */
  61 hb_tag_t vertical_features[] = {
  62   HB_TAG('v','a','l','t'),
  63   HB_TAG('v','e','r','t'),
  64   HB_TAG('v','k','r','n'),
  65   HB_TAG('v','p','a','l'),
  66   HB_TAG('v','r','t','2'),
  67 };
  68
  69 static void
  70 hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
  71                               const hb_segment_properties_t  *props,
  72                               const hb_feature_t             *user_features,
  73                               unsigned int                    num_user_features)
  74 {
  75   switch (props->direction) {
  76     case HB_DIRECTION_LTR:
  77       planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
  78       planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
  79       break;
  80     case HB_DIRECTION_RTL:
  81       planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
  82       planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
  83       break;
  84     case HB_DIRECTION_TTB:
  85     case HB_DIRECTION_BTT:
  86     case HB_DIRECTION_INVALID:
  87     default:
  88       break;
  89   }
  90
  91 #define ADD_FEATURES(array) \
  92   HB_STMT_START { \
  93     for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
  94       planner->map.add_bool_feature (array[i]); \
  95   } HB_STMT_END
  96
  97   ADD_FEATURES (early_features);
  98
  99   hb_ot_shape_complex_collect_features (planner, props);
 100
 101   ADD_FEATURES (common_features);
 102
 103   if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
 104     ADD_FEATURES (horizontal_features);
 105   else
 106     ADD_FEATURES (vertical_features);
 107
 108 #undef ADD_FEATURES
 109
 110   for (unsigned int i = 0; i < num_user_features; i++) {
 111     const hb_feature_t *feature = &user_features[i];
 112     planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
 113   }
 114 }
 115
 116
 117 static void
 118 hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
 119 {
 120   hb_mask_t global_mask = c->plan->map.get_global_mask ();
 121   c->buffer->reset_masks (global_mask);
 122
 123   hb_ot_shape_complex_setup_masks (c); /* BUFFER: Clobbers var2 */
 124
 125   for (unsigned int i = 0; i < c->num_user_features; i++)
 126   {
 127     const hb_feature_t *feature = &c->user_features[i];
 128     if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
 129       unsigned int shift;
 130       hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
 131       c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
 132     }
 133   }
 134 }
 135
 136
 137 static void
 138 hb_ot_substitute_complex (hb_ot_shape_context_t *c)
 139 {
 140   if (!hb_ot_layout_has_substitution (c->face))
 141     return;
 142
 143   c->plan->map.substitute (c->face, c->buffer);
 144
 145   c->applied_substitute_complex = TRUE;
 146   return;
 147 }
 148
 149 static void
 150 hb_ot_position_complex (hb_ot_shape_context_t *c)
 151 {
 152
 153   if (!hb_ot_layout_has_positioning (c->face))
 154     return;
 155
 156   unsigned int count = c->buffer->len;
 157   for (unsigned int i = 0; i < count; i++) {
 158     hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 159                                             HB_DIRECTION_LTR,
 160                                             &c->buffer->pos[i].x_offset,
 161                                             &c->buffer->pos[i].y_offset);
 162   }
 163
 164   c->plan->map.position (c->font, c->buffer);
 165
 166   for (unsigned int i = 0; i < count; i++) {
 167     hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 168                                                  HB_DIRECTION_LTR,
 169                                                  &c->buffer->pos[i].x_offset,
 170                                                  &c->buffer->pos[i].y_offset);
 171   }
 172
 173   hb_ot_layout_position_finish (c->buffer);
 174
 175   c->applied_position_complex = TRUE;
 176   return;
 177 }
 178
 179
 180 /* Main shaper */
 181
 182 /* Prepare */
 183
 184 static inline hb_bool_t
 185 is_variation_selector (hb_codepoint_t unicode)
 186 {
 187   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
 188                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
 189                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
 190 }
 191
 192 static void
 193 hb_set_unicode_props (hb_ot_shape_context_t *c)
 194 {
 195   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 196   hb_glyph_info_t *info = c->buffer->info;
 197
 198   unsigned int count = c->buffer->len;
 199   for (unsigned int i = 1; i < count; i++) {
 200     info[i].general_category() = unicode->get_general_category (info[i].codepoint);
 201     info[i].combining_class() = unicode->get_combining_class (info[i].codepoint);
 202   }
 203 }
 204
 205 static void
 206 hb_form_clusters (hb_ot_shape_context_t *c)
 207 {
 208   unsigned int count = c->buffer->len;
 209   for (unsigned int i = 1; i < count; i++)
 210     /* TODO: Match other mark types too? */
 211     if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 212       c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
 213 }
 214
 215 static void
 216 hb_ensure_native_direction (hb_ot_shape_context_t *c)
 217 {
 218   hb_direction_t direction = c->buffer->props.direction;
 219
 220   /* TODO vertical:
 221    * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
 222    * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
 223    * first. */
 224   if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (c->buffer->props.script)) ||
 225       (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
 226   {
 227     hb_buffer_reverse_clusters (c->buffer);
 228     c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
 229   }
 230 }
 231
 232 static void
 233 hb_reset_glyph_infos (hb_ot_shape_context_t *c)
 234 {
 235   unsigned int count = c->buffer->len;
 236   for (unsigned int i = 0; i < count; i++)
 237     c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
 238 }
 239
 240
 241 /* Substitute */
 242
 243 static void
 244 hb_mirror_chars (hb_ot_shape_context_t *c)
 245 {
 246   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 247
 248   if (HB_DIRECTION_IS_FORWARD (c->target_direction))
 249     return;
 250
 251   hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
 252
 253   unsigned int count = c->buffer->len;
 254   for (unsigned int i = 0; i < count; i++) {
 255     hb_codepoint_t codepoint = unicode->get_mirroring (c->buffer->info[i].codepoint);
 256     if (likely (codepoint == c->buffer->info[i].codepoint))
 257       c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
 258     else
 259       c->buffer->info[i].codepoint = codepoint;
 260   }
 261 }
 262
 263 static void
 264 hb_map_glyphs (hb_font_t    *font,
 265                hb_buffer_t  *buffer)
 266 {
 267   if (unlikely (!buffer->len))
 268     return;
 269
 270   hb_codepoint_t glyph;
 271   buffer->clear_output ();
 272   unsigned int count = buffer->len - 1;
 273   for (buffer->i = 0; buffer->i < count;) {
 274     if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
 275       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint, &glyph);
 276       buffer->replace_glyph (glyph);
 277       buffer->i++;
 278     } else {
 279       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
 280       buffer->replace_glyph (glyph);
 281     }
 282   }
 283   if (likely (buffer->i < buffer->len)) {
 284     hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
 285     buffer->replace_glyph (glyph);
 286   }
 287   buffer->swap ();
 288 }
 289
 290 static void
 291 hb_substitute_default (hb_ot_shape_context_t *c)
 292 {
 293   hb_map_glyphs (c->font, c->buffer);
 294 }
 295
 296 static void
 297 hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 298 {
 299   /* TODO Arabic */
 300 }
 301
 302
 303 /* Position */
 304
 305 static void
 306 hb_position_default (hb_ot_shape_context_t *c)
 307 {
 308   hb_ot_layout_position_start (c->buffer);
 309
 310   unsigned int count = c->buffer->len;
 311   for (unsigned int i = 0; i < count; i++) {
 312     hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
 313                                              c->buffer->props.direction,
 314                                              &c->buffer->pos[i].x_advance,
 315                                              &c->buffer->pos[i].y_advance);
 316     hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 317                                                  c->buffer->props.direction,
 318                                                  &c->buffer->pos[i].x_offset,
 319                                                  &c->buffer->pos[i].y_offset);
 320   }
 321 }
 322
 323 static void
 324 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 325 {
 326   /* TODO Mark pos */
 327 }
 328
 329 static void
 330 hb_truetype_kern (hb_ot_shape_context_t *c)
 331 {
 332   /* TODO Check for kern=0 */
 333   unsigned int count = c->buffer->len;
 334   for (unsigned int i = 1; i < count; i++) {
 335     hb_position_t x_kern, y_kern, kern1, kern2;
 336     hb_font_get_glyph_kerning_for_direction (c->font,
 337                                              c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
 338                                              c->buffer->props.direction,
 339                                              &x_kern, &y_kern);
 340
 341     kern1 = x_kern >> 1;
 342     kern2 = x_kern - kern1;
 343     c->buffer->pos[i - 1].x_advance += kern1;
 344     c->buffer->pos[i].x_advance += kern2;
 345     c->buffer->pos[i].x_offset += kern2;
 346
 347     kern1 = y_kern >> 1;
 348     kern2 = y_kern - kern1;
 349     c->buffer->pos[i - 1].y_advance += kern1;
 350     c->buffer->pos[i].y_advance += kern2;
 351     c->buffer->pos[i].y_offset += kern2;
 352   }
 353 }
 354
 355 static void
 356 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
 357 {
 358   hb_truetype_kern (c);
 359 }
 360
 361
 362 /* Do it! */
 363
 364 static void
 365 hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
 366 {
 367   /* Save the original direction, we use it later. */
 368   c->target_direction = c->buffer->props.direction;
 369
 370   hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
 371
 372   hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
 373
 374   hb_ensure_native_direction (c);
 375
 376   hb_form_clusters (c);
 377
 378   hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
 379
 380   /* SUBSTITUTE */
 381   {
 382     /* Mirroring needs to see the original direction */
 383     hb_mirror_chars (c);
 384
 385     hb_substitute_default (c);
 386
 387     hb_ot_substitute_complex (c);
 388
 389     if (!c->applied_substitute_complex)
 390       hb_substitute_complex_fallback (c);
 391   }
 392
 393   /* POSITION */
 394   {
 395     hb_position_default (c);
 396
 397     hb_ot_position_complex (c);
 398
 399     hb_bool_t position_fallback = !c->applied_position_complex;
 400     if (position_fallback)
 401       hb_position_complex_fallback (c);
 402
 403     if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 404       hb_buffer_reverse (c->buffer);
 405
 406     if (position_fallback)
 407       hb_position_complex_fallback_visual (c);
 408   }
 409
 410   c->buffer->props.direction = c->target_direction;
 411 }
 412
 413 static void
 414 hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
 415                            hb_face_t                *face,
 416                            const hb_segment_properties_t  *props,
 417                            const hb_feature_t       *user_features,
 418                            unsigned int              num_user_features)
 419 {
 420   hb_ot_shape_planner_t planner;
 421
 422   planner.shaper = hb_ot_shape_complex_categorize (props);
 423
 424   hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
 425
 426   planner.compile (face, props, *plan);
 427 }
 428
 429 static void
 430 hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
 431                      hb_font_t          *font,
 432                      hb_buffer_t        *buffer,
 433                      const hb_feature_t *user_features,
 434                      unsigned int        num_user_features)
 435 {
 436   hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
 437   hb_ot_shape_execute_internal (&c);
 438 }
 439
 440 void
 441 hb_ot_shape (hb_font_t          *font,
 442              hb_buffer_t        *buffer,
 443              const hb_feature_t *features,
 444              unsigned int        num_features)
 445 {
 446   hb_ot_shape_plan_t plan;
 447
 448   hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
 449   hb_ot_shape_execute (&plan, font, buffer, features, num_features);
 450 }
 451
 452
 453 HB_END_DECLS