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
  31 HB_BEGIN_DECLS
  32
  33
  34 /* XXX vertical */
  35 hb_tag_t default_features[] = {
  36   HB_TAG('c','a','l','t'),
  37   HB_TAG('c','c','m','p'),
  38   HB_TAG('c','l','i','g'),
  39   HB_TAG('c','s','w','h'),
  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     default:
  67       break;
  68   }
  69
  70   for (unsigned int i = 0; i < ARRAY_LENGTH (default_features); i++)
  71     plan->map.add_bool_feature (default_features[i]);
  72
  73   hb_ot_shape_complex_collect_features (plan, props);
  74
  75   for (unsigned int i = 0; i < num_user_features; i++) {
  76     const hb_feature_t *feature = &user_features[i];
  77     plan->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
  78   }
  79 }
  80
  81
  82 static void
  83 hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
  84 {
  85   hb_mask_t global_mask = c->plan->map.get_global_mask ();
  86   if (global_mask)
  87     c->buffer->set_masks (global_mask, global_mask, 0, (unsigned int) -1);
  88
  89   for (unsigned int i = 0; i < c->num_user_features; i++)
  90   {
  91     const hb_feature_t *feature = &c->user_features[i];
  92     if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
  93       unsigned int shift;
  94       hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
  95       c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
  96     }
  97   }
  98
  99   /* complex */
 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_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;
 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->add_output_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->add_output_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
 205     }
 206   }
 207   if (likely (buffer->i < buffer->len))
 208     buffer->add_output_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_glyph_metrics_t metrics;
 235     hb_font_get_glyph_metrics (c->font, c->face, c->buffer->info[i].codepoint, &metrics);
 236     c->buffer->pos[i].x_advance = metrics.x_advance;
 237     c->buffer->pos[i].y_advance = metrics.y_advance;
 238   }
 239 }
 240
 241 static void
 242 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 243 {
 244   /* TODO Mark pos */
 245 }
 246
 247 static void
 248 hb_truetype_kern (hb_ot_shape_context_t *c)
 249 {
 250   /* TODO Check for kern=0 */
 251   unsigned int count = c->buffer->len;
 252   for (unsigned int i = 1; i < count; i++) {
 253     hb_position_t kern, kern1, kern2;
 254     kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
 255     kern1 = kern >> 1;
 256     kern2 = kern - kern1;
 257     c->buffer->pos[i - 1].x_advance += kern1;
 258     c->buffer->pos[i].x_advance += kern2;
 259     c->buffer->pos[i].x_offset += kern2;
 260   }
 261 }
 262
 263 static void
 264 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
 265 {
 266   hb_truetype_kern (c);
 267 }
 268
 269
 270 /* Do it! */
 271
 272 static void
 273 hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
 274 {
 275   /* Save the original direction, we use it later. */
 276   c->original_direction = c->buffer->props.direction;
 277
 278   hb_ot_shape_setup_masks (c);
 279
 280   hb_form_clusters (c);
 281
 282   /* SUBSTITUTE */
 283   {
 284     c->buffer->clear_masks ();
 285
 286     /* Mirroring needs to see the original direction */
 287     hb_mirror_chars (c);
 288
 289     hb_ensure_native_direction (c);
 290
 291     hb_substitute_default (c);
 292
 293     hb_ot_substitute_complex (c);
 294
 295     if (!c->applied_substitute_complex)
 296       hb_substitute_complex_fallback (c);
 297   }
 298
 299   /* POSITION */
 300   {
 301     c->buffer->clear_masks ();
 302
 303     hb_position_default (c);
 304
 305     hb_ot_position_complex (c);
 306
 307     hb_bool_t position_fallback = !c->applied_position_complex;
 308     if (position_fallback)
 309       hb_position_complex_fallback (c);
 310
 311     if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 312       hb_buffer_reverse (c->buffer);
 313
 314     if (position_fallback)
 315       hb_position_complex_fallback_visual (c);
 316   }
 317
 318   c->buffer->props.direction = c->original_direction;
 319 }
 320
 321 void
 322 hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
 323                            hb_face_t                *face,
 324                            const hb_segment_properties_t  *props,
 325                            const hb_feature_t       *user_features,
 326                            unsigned int              num_user_features)
 327 {
 328   plan->shaper = hb_ot_shape_complex_categorize (props);
 329
 330   hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
 331
 332   plan->map.compile (face, props);
 333 }
 334
 335 void
 336 hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
 337                      hb_font_t          *font,
 338                      hb_face_t          *face,
 339                      hb_buffer_t        *buffer,
 340                      const hb_feature_t *user_features,
 341                      unsigned int        num_user_features)
 342 {
 343   hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
 344   hb_ot_shape_execute_internal (&c);
 345 }
 346
 347 void
 348 hb_ot_shape (hb_font_t    *font,
 349              hb_face_t    *face,
 350              hb_buffer_t  *buffer,
 351              const hb_feature_t *user_features,
 352              unsigned int        num_user_features)
 353 {
 354   hb_ot_shape_plan_t plan;
 355
 356   hb_ot_shape_plan_internal (&plan, face, &buffer->props, user_features, num_user_features);
 357   hb_ot_shape_execute (&plan, font, face, buffer, user_features, num_user_features);
 358 }
 359
 360
 361 HB_END_DECLS