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