src/hb-shape.cc

   1 /*
   2  * Copyright (C) 2009  Red Hat, 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  * Red Hat Author(s): Behdad Esfahbod
  25  */
  26
  27 #include "hb-private.h"
  28
  29 #include "hb-shape.h"
  30
  31 #include "hb-buffer-private.hh"
  32
  33 #include "hb-ot-shape-private.hh"
  34
  35 #ifdef HAVE_GRAPHITE
  36 #include "hb-graphite.h"
  37 #endif
  38
  39 /* Prepare */
  40
  41 static inline hb_bool_t
  42 is_variation_selector (hb_codepoint_t unicode)
  43 {
  44   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
  45                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
  46                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
  47 }
  48
  49 static void
  50 hb_form_clusters (hb_buffer_t *buffer)
  51 {
  52   unsigned int count = buffer->len;
  53   for (unsigned int i = 1; i < count; i++)
  54     if (buffer->unicode->get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
  55       buffer->info[i].cluster = buffer->info[i - 1].cluster;
  56 }
  57
  58 static hb_direction_t
  59 hb_ensure_native_direction (hb_buffer_t *buffer)
  60 {
  61   hb_direction_t original_direction = buffer->direction;
  62
  63   /* TODO vertical */
  64   if (HB_DIRECTION_IS_HORIZONTAL (original_direction) &&
  65       original_direction != _hb_script_get_horizontal_direction (buffer->script))
  66   {
  67     hb_buffer_reverse_clusters (buffer);
  68     buffer->direction = HB_DIRECTION_REVERSE (buffer->direction);
  69   }
  70
  71   return original_direction;
  72 }
  73
  74
  75 /* Substitute */
  76
  77 static void
  78 hb_mirror_chars (hb_buffer_t *buffer)
  79 {
  80   hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->get_mirroring;
  81
  82   if (HB_DIRECTION_IS_FORWARD (buffer->direction))
  83     return;
  84
  85   unsigned int count = buffer->len;
  86   for (unsigned int i = 0; i < count; i++) {
  87       buffer->info[i].codepoint = get_mirroring (buffer->info[i].codepoint);
  88   }
  89 }
  90
  91 static void
  92 hb_map_glyphs (hb_font_t    *font,
  93                hb_face_t    *face,
  94                hb_buffer_t  *buffer)
  95 {
  96   if (unlikely (!buffer->len))
  97     return;
  98
  99   unsigned int count = buffer->len - 1;
 100   for (unsigned int i = 0; i < count; i++) {
 101     if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) {
 102       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint);
 103       i++;
 104     } else {
 105       buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0);
 106     }
 107   }
 108   buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0);
 109 }
 110
 111 static void
 112 hb_substitute_default (hb_font_t    *font,
 113                        hb_face_t    *face,
 114                        hb_buffer_t  *buffer,
 115                        hb_feature_t *features HB_UNUSED,
 116                        unsigned int  num_features HB_UNUSED)
 117 {
 118   hb_mirror_chars (buffer);
 119   hb_map_glyphs (font, face, buffer);
 120 }
 121
 122 static hb_bool_t
 123 hb_substitute_complex (hb_font_t    *font,
 124                        hb_face_t    *face,
 125                        hb_buffer_t  *buffer,
 126                        hb_feature_t *features,
 127                        unsigned int  num_features)
 128 {
 129   return _hb_ot_substitute_complex (font, face, buffer, features, num_features);
 130 }
 131
 132 static void
 133 hb_substitute_fallback (hb_font_t    *font HB_UNUSED,
 134                         hb_face_t    *face HB_UNUSED,
 135                         hb_buffer_t  *buffer HB_UNUSED,
 136                         hb_feature_t *features HB_UNUSED,
 137                         unsigned int  num_features HB_UNUSED)
 138 {
 139   /* TODO Arabic */
 140 }
 141
 142
 143 /* Position */
 144
 145 static void
 146 hb_position_default (hb_font_t    *font,
 147                      hb_face_t    *face,
 148                      hb_buffer_t  *buffer,
 149                      hb_feature_t *features HB_UNUSED,
 150                      unsigned int  num_features HB_UNUSED)
 151 {
 152   hb_buffer_clear_positions (buffer);
 153
 154   unsigned int count = buffer->len;
 155   for (unsigned int i = 0; i < count; i++) {
 156     hb_glyph_metrics_t metrics;
 157     hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics);
 158     buffer->pos[i].x_advance = metrics.x_advance;
 159     buffer->pos[i].y_advance = metrics.y_advance;
 160   }
 161 }
 162
 163 static hb_bool_t
 164 hb_position_complex (hb_font_t    *font,
 165                      hb_face_t    *face,
 166                      hb_buffer_t  *buffer,
 167                      hb_feature_t *features,
 168                      unsigned int  num_features)
 169 {
 170   return _hb_ot_position_complex (font, face, buffer, features, num_features);
 171 }
 172
 173 static void
 174 hb_position_fallback (hb_font_t    *font HB_UNUSED,
 175                       hb_face_t    *face HB_UNUSED,
 176                       hb_buffer_t  *buffer HB_UNUSED,
 177                       hb_feature_t *features HB_UNUSED,
 178                       unsigned int  num_features HB_UNUSED)
 179 {
 180   /* TODO Mark pos */
 181 }
 182
 183 static void
 184 hb_truetype_kern (hb_font_t    *font,
 185                   hb_face_t    *face,
 186                   hb_buffer_t  *buffer,
 187                   hb_feature_t *features HB_UNUSED,
 188                   unsigned int  num_features HB_UNUSED)
 189 {
 190   /* TODO Check for kern=0 */
 191   unsigned int count = buffer->len;
 192   for (unsigned int i = 1; i < count; i++) {
 193     hb_position_t kern, kern1, kern2;
 194     kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint);
 195     kern1 = kern >> 1;
 196     kern2 = kern - kern1;
 197     buffer->pos[i - 1].x_advance += kern1;
 198     buffer->pos[i].x_advance += kern2;
 199     buffer->pos[i].x_offset += kern2;
 200   }
 201 }
 202
 203 static void
 204 hb_position_fallback_visual (hb_font_t    *font,
 205                              hb_face_t    *face,
 206                              hb_buffer_t  *buffer,
 207                              hb_feature_t *features,
 208                              unsigned int  num_features)
 209 {
 210   hb_truetype_kern (font, face, buffer, features, num_features);
 211 }
 212
 213
 214 /* Shape */
 215
 216 void
 217 hb_shape (hb_font_t    *font,
 218           hb_face_t    *face,
 219           hb_buffer_t  *buffer,
 220           hb_feature_t *features,
 221           unsigned int  num_features)
 222 {
 223   hb_direction_t original_direction;
 224   hb_bool_t substitute_fallback, position_fallback;
 225
 226 #ifdef HAVE_GRAPHITE
 227   hb_blob_t *silf_blob;
 228   silf_blob = hb_face_get_table (face, HB_GRAPHITE_TAG_Silf);
 229   if (hb_blob_get_length(silf_blob))
 230   {
 231     hb_graphite_shape(font, face, buffer, features, num_features);
 232     hb_blob_destroy(silf_blob);
 233     return;
 234   }
 235   hb_blob_destroy(silf_blob);
 236 #endif
 237
 238   hb_form_clusters (buffer);
 239
 240   hb_substitute_default (font, face, buffer, features, num_features);
 241
 242   /* We do this after substitute_default because mirroring needs to
 243    * see the original direction. */
 244   original_direction = hb_ensure_native_direction (buffer);
 245
 246   substitute_fallback = !hb_substitute_complex (font, face, buffer, features, num_features);
 247
 248   if (substitute_fallback)
 249     hb_substitute_fallback (font, face, buffer, features, num_features);
 250
 251   hb_position_default (font, face, buffer, features, num_features);
 252
 253   position_fallback = !hb_position_complex (font, face, buffer, features, num_features);
 254
 255   if (position_fallback)
 256     hb_position_fallback (font, face, buffer, features, num_features);
 257
 258   if (HB_DIRECTION_IS_BACKWARD (buffer->direction))
 259     hb_buffer_reverse (buffer);
 260
 261   if (position_fallback)
 262     hb_position_fallback_visual (font, face, buffer, features, num_features);
 263
 264   buffer->direction = original_direction;
 265 }