src/hb-ot-shape-complex-arabic-fallback.hh

   1 /*
   2  * Copyright © 2012  Google, 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  * Google Author(s): Behdad Esfahbod
  25  */
  26
  27 #ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
  28 #define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
  29
  30 #include "hb-private.hh"
  31
  32 #include "hb-ot-shape-private.hh"
  33 #include "hb-ot-layout-gsub-table.hh"
  34
  35
  36 static const hb_tag_t arabic_fallback_features[] =
  37 {
  38   HB_TAG('i','n','i','t'),
  39   HB_TAG('m','e','d','i'),
  40   HB_TAG('f','i','n','a'),
  41   HB_TAG('i','s','o','l'),
  42   HB_TAG('r','l','i','g'),
  43 };
  44
  45 /* Same order as the fallback feature array */
  46 enum {
  47   FALLBACK_INIT,
  48   FALLBACK_MEDI,
  49   FALLBACK_FINA,
  50   FALLBACK_ISOL,
  51   FALLBACK_RLIG,
  52   ARABIC_NUM_FALLBACK_FEATURES
  53 };
  54
  55 static OT::SubstLookup *
  56 arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
  57                                           hb_font_t *font,
  58                                           unsigned int feature_index)
  59 {
  60   OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
  61   OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
  62   unsigned int num_glyphs = 0;
  63
  64   /* Populate arrays */
  65   for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
  66   {
  67     hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
  68     hb_codepoint_t u_glyph, s_glyph;
  69
  70     if (!s ||
  71         !hb_font_get_glyph (font, u, 0, &u_glyph) ||
  72         !hb_font_get_glyph (font, s, 0, &s_glyph) ||
  73         u_glyph == s_glyph ||
  74         u_glyph > 0xFFFF || s_glyph > 0xFFFF)
  75       continue;
  76
  77     glyphs[num_glyphs].set (u_glyph);
  78     substitutes[num_glyphs].set (s_glyph);
  79
  80     num_glyphs++;
  81   }
  82
  83   /* Bubble-sort!
  84    * May not be good-enough for presidential candidate interviews, but good-enough for us... */
  85   hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);
  86
  87   OT::Supplier<OT::GlyphID> glyphs_supplier      (glyphs, num_glyphs);
  88   OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);
  89
  90   /* Each glyph takes four bytes max, and there's some overhead. */
  91   char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
  92   OT::hb_serialize_context_t c (buf, sizeof (buf));
  93   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
  94   bool ret = lookup->serialize_single (&c,
  95                                        OT::LookupFlag::IgnoreMarks,
  96                                        glyphs_supplier,
  97                                        substitutes_supplier,
  98                                        num_glyphs);
  99   c.end_serialize ();
 100   /* TODO sanitize the results? */
 101
 102   return ret ? c.copy<OT::SubstLookup> () : NULL;
 103 }
 104
 105 static OT::SubstLookup *
 106 arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
 107                                             hb_font_t *font)
 108 {
 109   OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
 110   unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
 111   unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
 112   unsigned int num_first_glyphs = 0;
 113
 114   /* We know that all our ligatures are 2-component */
 115   OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
 116   unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
 117   OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
 118   unsigned int num_ligatures = 0;
 119
 120   /* Populate arrays */
 121
 122   /* Sort out the first-glyphs */
 123   for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
 124   {
 125     hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
 126     hb_codepoint_t first_glyph;
 127     if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
 128       continue;
 129     first_glyphs[num_first_glyphs].set (first_glyph);
 130     ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
 131     first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
 132     num_first_glyphs++;
 133   }
 134   hb_bubble_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);
 135
 136   /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
 137   for (unsigned int i = 0; i < num_first_glyphs; i++)
 138   {
 139     unsigned int first_glyph_idx = first_glyphs_indirection[i];
 140
 141     for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
 142     {
 143       hb_codepoint_t second_u   = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
 144       hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
 145       hb_codepoint_t second_glyph, ligature_glyph;
 146       if (!second_u ||
 147           !hb_font_get_glyph (font, second_u,   0, &second_glyph) ||
 148           !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
 149         continue;
 150
 151       ligature_per_first_glyph_count_list[i]++;
 152
 153       ligature_list[num_ligatures].set (ligature_glyph);
 154       component_count_list[num_ligatures] = 2;
 155       component_list[num_ligatures].set (second_glyph);
 156       num_ligatures++;
 157     }
 158   }
 159
 160   OT::Supplier<OT::GlyphID>   first_glyphs_supplier                      (first_glyphs, num_first_glyphs);
 161   OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier    (ligature_per_first_glyph_count_list, num_first_glyphs);
 162   OT::Supplier<OT::GlyphID>   ligatures_supplier                         (ligature_list, num_ligatures);
 163   OT::Supplier<unsigned int > component_count_supplier                   (component_count_list, num_ligatures);
 164   OT::Supplier<OT::GlyphID>   component_supplier                         (component_list, num_ligatures);
 165
 166   /* 16 bytes per ligature ought to be enough... */
 167   char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
 168   OT::hb_serialize_context_t c (buf, sizeof (buf));
 169   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
 170   bool ret = lookup->serialize_ligature (&c,
 171                                          OT::LookupFlag::IgnoreMarks,
 172                                          first_glyphs_supplier,
 173                                          ligature_per_first_glyph_count_supplier,
 174                                          num_first_glyphs,
 175                                          ligatures_supplier,
 176                                          component_count_supplier,
 177                                          component_supplier);
 178
 179   c.end_serialize ();
 180   /* TODO sanitize the results? */
 181
 182   return ret ? c.copy<OT::SubstLookup> () : NULL;
 183 }
 184
 185 static OT::SubstLookup *
 186 arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
 187                                    hb_font_t *font,
 188                                    unsigned int feature_index)
 189 {
 190   if (feature_index < 4)
 191     return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
 192   else
 193     return arabic_fallback_synthesize_lookup_ligature (plan, font);
 194 }
 195
 196 struct arabic_fallback_plan_t
 197 {
 198   ASSERT_POD ();
 199
 200   hb_mask_t mask_array[ARABIC_NUM_FALLBACK_FEATURES];
 201   OT::SubstLookup *lookup_array[ARABIC_NUM_FALLBACK_FEATURES];
 202   hb_set_digest_t digest_array[ARABIC_NUM_FALLBACK_FEATURES];
 203 };
 204
 205 static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
 206
 207 static arabic_fallback_plan_t *
 208 arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
 209                              hb_font_t *font)
 210 {
 211   arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
 212   if (unlikely (!fallback_plan))
 213     return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
 214
 215   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++) {
 216     fallback_plan->mask_array[i] = plan->map.get_1_mask (arabic_fallback_features[i]);
 217     if (fallback_plan->mask_array[i]) {
 218       fallback_plan->lookup_array[i] = arabic_fallback_synthesize_lookup (plan, font, i);
 219       if (fallback_plan->lookup_array[i])
 220         fallback_plan->lookup_array[i]->add_coverage (&fallback_plan->digest_array[i]);
 221     }
 222   }
 223
 224   return fallback_plan;
 225 }
 226
 227 static void
 228 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
 229 {
 230   if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
 231     return;
 232
 233   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
 234     if (fallback_plan->lookup_array[i])
 235       free (fallback_plan->lookup_array[i]);
 236
 237   free (fallback_plan);
 238 }
 239
 240 static void
 241 arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
 242                             hb_font_t *font,
 243                             hb_buffer_t *buffer)
 244 {
 245   for (unsigned int i = 0; i < ARABIC_NUM_FALLBACK_FEATURES; i++)
 246     if (fallback_plan->lookup_array[i]) {
 247       OT::hb_apply_context_t c (font, buffer, fallback_plan->mask_array[i]);
 248       fallback_plan->lookup_array[i]->apply_string (&c, &fallback_plan->digest_array[i]);
 249     }
 250 }
 251
 252
 253 #endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */