src/hb-ot-shape.cc

   1 /*
   2  * Copyright (C) 2009,2010  Red Hat, Inc.
   3  * Copyright (C) 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','s','w','h'),
  41   HB_TAG('c','u','r','s'),
  42   HB_TAG('k','e','r','n'),
  43   HB_TAG('l','i','g','a'),
  44   HB_TAG('l','o','c','l'),
  45   HB_TAG('m','a','r','k'),
  46   HB_TAG('m','k','m','k'),
  47   HB_TAG('r','l','i','g')
  48 };
  49
  50 static void
  51 hb_ot_shape_collect_features (hb_ot_shape_plan_t       *plan,
  52                               const hb_segment_properties_t  *props,
  53                               const hb_feature_t       *user_features,
  54                               unsigned int              num_user_features)
  55 {
  56   switch (props->direction) {
  57     case HB_DIRECTION_LTR:
  58       plan->map.add_bool_feature (HB_TAG ('l','t','r','a'));
  59       plan->map.add_bool_feature (HB_TAG ('l','t','r','m'));
  60       break;
  61     case HB_DIRECTION_RTL:
  62       plan->map.add_bool_feature (HB_TAG ('r','t','l','a'));
  63       plan->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
  64       break;
  65     case HB_DIRECTION_TTB:
  66     case HB_DIRECTION_BTT:
  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);
  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->font, c->face, 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_form_clusters (hb_ot_shape_context_t *c)
 145 {
 146   unsigned int count = c->buffer->len;
 147   for (unsigned int i = 1; i < count; i++)
 148     if (c->buffer->unicode->v.get_general_category (c->buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
 149       c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
 150 }
 151
 152 static void
 153 hb_ensure_native_direction (hb_ot_shape_context_t *c)
 154 {
 155   hb_direction_t direction = c->buffer->props.direction;
 156
 157   /* TODO vertical */
 158   if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
 159       direction != _hb_script_get_horizontal_direction (c->buffer->props.script))
 160   {
 161     hb_buffer_reverse_clusters (c->buffer);
 162     c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
 163   }
 164 }
 165
 166
 167 /* Substitute */
 168
 169 static void
 170 hb_mirror_chars (hb_ot_shape_context_t *c)
 171 {
 172   hb_unicode_get_mirroring_func_t get_mirroring = c->buffer->unicode->v.get_mirroring;
 173
 174   if (HB_DIRECTION_IS_FORWARD (c->buffer->props.direction))
 175     return;
 176
 177   hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
 178
 179   unsigned int count = c->buffer->len;
 180   for (unsigned int i = 0; i < count; i++) {
 181     hb_codepoint_t codepoint = get_mirroring (c->buffer->info[i].codepoint);
 182     if (likely (codepoint == c->buffer->info[i].codepoint))
 183       c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
 184     else
 185       c->buffer->info[i].codepoint = codepoint;
 186   }
 187 }
 188
 189 static void
 190 hb_map_glyphs (hb_font_t    *font,
 191                hb_face_t    *face,
 192                hb_buffer_t  *buffer)
 193 {
 194   if (unlikely (!buffer->len))
 195     return;
 196
 197   buffer->clear_output ();
 198   unsigned int count = buffer->len - 1;
 199   for (buffer->i = 0; buffer->i < count;) {
 200     if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
 201       buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
 202       buffer->i++;
 203     } else {
 204       buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
 205     }
 206   }
 207   if (likely (buffer->i < buffer->len))
 208     buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
 209   buffer->swap ();
 210 }
 211
 212 static void
 213 hb_substitute_default (hb_ot_shape_context_t *c)
 214 {
 215   hb_map_glyphs (c->font, c->face, c->buffer);
 216 }
 217
 218 static void
 219 hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 220 {
 221   /* TODO Arabic */
 222 }
 223
 224
 225 /* Position */
 226
 227 static void
 228 hb_position_default (hb_ot_shape_context_t *c)
 229 {
 230   hb_buffer_clear_positions (c->buffer);
 231
 232   unsigned int count = c->buffer->len;
 233   for (unsigned int i = 0; i < count; i++) {
 234     hb_font_get_glyph_advance (c->font, c->face, c->buffer->info[i].codepoint,
 235                                &c->buffer->pos[i].x_advance,
 236                                &c->buffer->pos[i].y_advance);
 237   }
 238 }
 239
 240 static void
 241 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 242 {
 243   /* TODO Mark pos */
 244 }
 245
 246 static void
 247 hb_truetype_kern (hb_ot_shape_context_t *c)
 248 {
 249   /* TODO Check for kern=0 */
 250   unsigned int count = c->buffer->len;
 251   for (unsigned int i = 1; i < count; i++) {
 252     hb_position_t kern, kern1, kern2;
 253     kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
 254     kern1 = kern >> 1;
 255     kern2 = kern - kern1;
 256     c->buffer->pos[i - 1].x_advance += kern1;
 257     c->buffer->pos[i].x_advance += kern2;
 258     c->buffer->pos[i].x_offset += kern2;
 259   }
 260 }
 261
 262 static void
 263 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
 264 {
 265   hb_truetype_kern (c);
 266 }
 267
 268
 269 /* Do it! */
 270
 271 static void
 272 hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
 273 {
 274   /* Save the original direction, we use it later. */
 275   c->original_direction = c->buffer->props.direction;
 276
 277   hb_form_clusters (c);
 278
 279   hb_ot_shape_setup_masks (c);
 280
 281   /* SUBSTITUTE */
 282   {
 283     /* Mirroring needs to see the original direction */
 284     hb_mirror_chars (c);
 285
 286     hb_ensure_native_direction (c);
 287
 288     hb_substitute_default (c);
 289
 290     hb_ot_substitute_complex (c);
 291
 292     if (!c->applied_substitute_complex)
 293       hb_substitute_complex_fallback (c);
 294   }
 295
 296   /* POSITION */
 297   {
 298     hb_position_default (c);
 299
 300     hb_ot_position_complex (c);
 301
 302     hb_bool_t position_fallback = !c->applied_position_complex;
 303     if (position_fallback)
 304       hb_position_complex_fallback (c);
 305
 306     if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 307       hb_buffer_reverse (c->buffer);
 308
 309     if (position_fallback)
 310       hb_position_complex_fallback_visual (c);
 311   }
 312
 313   c->buffer->props.direction = c->original_direction;
 314 }
 315
 316 void
 317 hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
 318                            hb_face_t                *face,
 319                            const hb_segment_properties_t  *props,
 320                            const hb_feature_t       *user_features,
 321                            unsigned int              num_user_features)
 322 {
 323   plan->shaper = hb_ot_shape_complex_categorize (props);
 324
 325   hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
 326
 327   plan->map.compile (face, props);
 328 }
 329
 330 void
 331 hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
 332                      hb_font_t          *font,
 333                      hb_face_t          *face,
 334                      hb_buffer_t        *buffer,
 335                      const hb_feature_t *user_features,
 336                      unsigned int        num_user_features)
 337 {
 338   hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
 339   hb_ot_shape_execute_internal (&c);
 340 }
 341
 342 void
 343 hb_ot_shape (hb_font_t    *font,
 344              hb_face_t    *face,
 345              hb_buffer_t  *buffer,
 346              const hb_feature_t *user_features,
 347              unsigned int        num_user_features)
 348 {
 349   hb_ot_shape_plan_t plan;
 350
 351   hb_ot_shape_plan_internal (&plan, face, &buffer->props, user_features, num_user_features);
 352   hb_ot_shape_execute (&plan, font, face, buffer, user_features, num_user_features);
 353 }
 354
 355
 356 HB_END_DECLS