src/hb-ot-shape.cc

   1 /*
   2  * Copyright © 2009,2010  Red Hat, Inc.
   3  * Copyright © 2010  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 HB_BEGIN_DECLS
  33
  34
  35 /* XXX vertical */
  36 hb_tag_t default_features[] = {
  37   HB_TAG('c','a','l','t'),
  38   HB_TAG('c','c','m','p'),
  39   HB_TAG('c','l','i','g'),
  40   HB_TAG('c','u','r','s'),
  41   HB_TAG('k','e','r','n'),
  42   HB_TAG('l','i','g','a'),
  43   HB_TAG('l','o','c','l'),
  44   HB_TAG('m','a','r','k'),
  45   HB_TAG('m','k','m','k'),
  46   HB_TAG('r','l','i','g')
  47 };
  48
  49 static void
  50 hb_ot_shape_collect_features (hb_ot_shape_plan_t       *plan,
  51                               const hb_segment_properties_t  *props,
  52                               const hb_feature_t       *user_features,
  53                               unsigned int              num_user_features)
  54 {
  55   switch (props->direction) {
  56     case HB_DIRECTION_LTR:
  57       plan->map.add_bool_feature (HB_TAG ('l','t','r','a'));
  58       plan->map.add_bool_feature (HB_TAG ('l','t','r','m'));
  59       break;
  60     case HB_DIRECTION_RTL:
  61       plan->map.add_bool_feature (HB_TAG ('r','t','l','a'));
  62       plan->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
  63       break;
  64     case HB_DIRECTION_TTB:
  65     case HB_DIRECTION_BTT:
  66     case HB_DIRECTION_INVALID:
  67     default:
  68       break;
  69   }
  70
  71   for (unsigned int i = 0; i < ARRAY_LENGTH (default_features); i++)
  72     plan->map.add_bool_feature (default_features[i]);
  73
  74   hb_ot_shape_complex_collect_features (plan, props);
  75
  76   for (unsigned int i = 0; i < num_user_features; i++) {
  77     const hb_feature_t *feature = &user_features[i];
  78     plan->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
  79   }
  80 }
  81
  82
  83 static void
  84 hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
  85 {
  86   hb_mask_t global_mask = c->plan->map.get_global_mask ();
  87   c->buffer->reset_masks (global_mask);
  88
  89   hb_ot_shape_complex_setup_masks (c); /* BUFFER: Clobbers var2 */
  90
  91   for (unsigned int i = 0; i < c->num_user_features; i++)
  92   {
  93     const hb_feature_t *feature = &c->user_features[i];
  94     if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
  95       unsigned int shift;
  96       hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
  97       c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
  98     }
  99   }
 100 }
 101
 102
 103 static void
 104 hb_ot_substitute_complex (hb_ot_shape_context_t *c)
 105 {
 106   if (!hb_ot_layout_has_substitution (c->face))
 107     return;
 108
 109   c->plan->map.substitute (c->face, c->buffer);
 110
 111   c->applied_substitute_complex = TRUE;
 112   return;
 113 }
 114
 115 static void
 116 hb_ot_position_complex (hb_ot_shape_context_t *c)
 117 {
 118
 119   if (!hb_ot_layout_has_positioning (c->face))
 120     return;
 121
 122   c->plan->map.position (c->font, c->face, c->buffer);
 123
 124   hb_ot_layout_position_finish (c->buffer);
 125
 126   c->applied_position_complex = TRUE;
 127   return;
 128 }
 129
 130
 131 /* Main shaper */
 132
 133 /* Prepare */
 134
 135 static inline hb_bool_t
 136 is_variation_selector (hb_codepoint_t unicode)
 137 {
 138   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
 139                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
 140                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
 141 }
 142
 143 static void
 144 hb_set_unicode_props (hb_ot_shape_context_t *c)
 145 {
 146   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 147   hb_glyph_info_t *info = c->buffer->info;
 148
 149   unsigned int count = c->buffer->len;
 150   for (unsigned int i = 1; i < count; i++) {
 151     info[i].general_category() = unicode->get_general_category (info[i].codepoint);
 152     info[i].combining_class() = unicode->get_combining_class (info[i].codepoint);
 153   }
 154 }
 155
 156 static void
 157 hb_form_clusters (hb_ot_shape_context_t *c)
 158 {
 159   unsigned int count = c->buffer->len;
 160   for (unsigned int i = 1; i < count; i++)
 161     if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 162       c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
 163 }
 164
 165 static void
 166 hb_ensure_native_direction (hb_ot_shape_context_t *c)
 167 {
 168   hb_direction_t direction = c->buffer->props.direction;
 169
 170   /* TODO vertical */
 171   if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
 172       direction != hb_script_get_horizontal_direction (c->buffer->props.script))
 173   {
 174     hb_buffer_reverse_clusters (c->buffer);
 175     c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
 176   }
 177 }
 178
 179 static void
 180 hb_reset_glyph_infos (hb_ot_shape_context_t *c)
 181 {
 182   unsigned int count = c->buffer->len;
 183   for (unsigned int i = 0; i < count; i++)
 184     c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
 185 }
 186
 187
 188 /* Substitute */
 189
 190 static void
 191 hb_mirror_chars (hb_ot_shape_context_t *c)
 192 {
 193   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 194
 195   if (HB_DIRECTION_IS_FORWARD (c->target_direction))
 196     return;
 197
 198   hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
 199
 200   unsigned int count = c->buffer->len;
 201   for (unsigned int i = 0; i < count; i++) {
 202     hb_codepoint_t codepoint = unicode->get_mirroring (c->buffer->info[i].codepoint);
 203     if (likely (codepoint == c->buffer->info[i].codepoint))
 204       c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
 205     else
 206       c->buffer->info[i].codepoint = codepoint;
 207   }
 208 }
 209
 210 static void
 211 hb_map_glyphs (hb_font_t    *font,
 212                hb_face_t    *face,
 213                hb_buffer_t  *buffer)
 214 {
 215   if (unlikely (!buffer->len))
 216     return;
 217
 218   buffer->clear_output ();
 219   unsigned int count = buffer->len - 1;
 220   for (buffer->i = 0; buffer->i < count;) {
 221     if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
 222       buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
 223       buffer->i++;
 224     } else {
 225       buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
 226     }
 227   }
 228   if (likely (buffer->i < buffer->len))
 229     buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
 230   buffer->swap ();
 231 }
 232
 233 static void
 234 hb_substitute_default (hb_ot_shape_context_t *c)
 235 {
 236   hb_map_glyphs (c->font, c->face, c->buffer);
 237 }
 238
 239 static void
 240 hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 241 {
 242   /* TODO Arabic */
 243 }
 244
 245
 246 /* Position */
 247
 248 static void
 249 hb_position_default (hb_ot_shape_context_t *c)
 250 {
 251   hb_ot_layout_position_start (c->buffer);
 252
 253   unsigned int count = c->buffer->len;
 254   for (unsigned int i = 0; i < count; i++) {
 255     hb_font_get_glyph_advance (c->font, c->face, c->buffer->info[i].codepoint,
 256                                &c->buffer->pos[i].x_advance,
 257                                &c->buffer->pos[i].y_advance);
 258   }
 259 }
 260
 261 static void
 262 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 263 {
 264   /* TODO Mark pos */
 265 }
 266
 267 static void
 268 hb_truetype_kern (hb_ot_shape_context_t *c)
 269 {
 270   /* TODO Check for kern=0 */
 271   unsigned int count = c->buffer->len;
 272   for (unsigned int i = 1; i < count; i++) {
 273     hb_position_t kern, kern1, kern2;
 274     kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
 275     kern1 = kern >> 1;
 276     kern2 = kern - kern1;
 277     c->buffer->pos[i - 1].x_advance += kern1;
 278     c->buffer->pos[i].x_advance += kern2;
 279     c->buffer->pos[i].x_offset += kern2;
 280   }
 281 }
 282
 283 static void
 284 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
 285 {
 286   hb_truetype_kern (c);
 287 }
 288
 289
 290 /* Do it! */
 291
 292 static void
 293 hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
 294 {
 295   /* Save the original direction, we use it later. */
 296   c->target_direction = c->buffer->props.direction;
 297
 298   hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
 299
 300   hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
 301
 302   hb_ensure_native_direction (c);
 303
 304   hb_form_clusters (c);
 305
 306   hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
 307
 308   /* SUBSTITUTE */
 309   {
 310     /* Mirroring needs to see the original direction */
 311     hb_mirror_chars (c);
 312
 313     hb_substitute_default (c);
 314
 315     hb_ot_substitute_complex (c);
 316
 317     if (!c->applied_substitute_complex)
 318       hb_substitute_complex_fallback (c);
 319   }
 320
 321   /* POSITION */
 322   {
 323     hb_position_default (c);
 324
 325     hb_ot_position_complex (c);
 326
 327     hb_bool_t position_fallback = !c->applied_position_complex;
 328     if (position_fallback)
 329       hb_position_complex_fallback (c);
 330
 331     if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 332       hb_buffer_reverse (c->buffer);
 333
 334     if (position_fallback)
 335       hb_position_complex_fallback_visual (c);
 336   }
 337
 338   c->buffer->props.direction = c->target_direction;
 339 }
 340
 341 void
 342 hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
 343                            hb_face_t                *face,
 344                            const hb_segment_properties_t  *props,
 345                            const hb_feature_t       *user_features,
 346                            unsigned int              num_user_features)
 347 {
 348   plan->shaper = hb_ot_shape_complex_categorize (props);
 349
 350   hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
 351
 352   plan->map.compile (face, props);
 353 }
 354
 355 void
 356 hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
 357                      hb_font_t          *font,
 358                      hb_face_t          *face,
 359                      hb_buffer_t        *buffer,
 360                      const hb_feature_t *user_features,
 361                      unsigned int        num_user_features)
 362 {
 363   hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
 364   hb_ot_shape_execute_internal (&c);
 365 }
 366
 367 void
 368 hb_ot_shape (hb_font_t          *font,
 369              hb_face_t          *face,
 370              hb_buffer_t        *buffer,
 371              const hb_feature_t *features,
 372              unsigned int        num_features)
 373 {
 374   hb_ot_shape_plan_t plan;
 375
 376   hb_ot_shape_plan_internal (&plan, face, &buffer->props, features, num_features);
 377   hb_ot_shape_execute (&plan, font, face, buffer, features, num_features);
 378 }
 379
 380
 381 HB_END_DECLS