hb-ot-shaper-arabic-fallback.hh (13157B)
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_SHAPER_ARABIC_FALLBACK_HH 28 #define HB_OT_SHAPER_ARABIC_FALLBACK_HH 29 30 #include "hb.hh" 31 32 #include "hb-ot-shape.hh" 33 #include "hb-ot-layout-gsub-table.hh" 34 35 36 /* Features ordered the same as the entries in shaping_table rows, 37 * followed by rlig. Don't change. 38 * 39 * We currently support one subtable per lookup, and one lookup 40 * per feature. But we allow duplicate features, so we use that! 41 */ 42 static const hb_tag_t arabic_fallback_features[] = 43 { 44 HB_TAG('i','n','i','t'), 45 HB_TAG('m','e','d','i'), 46 HB_TAG('f','i','n','a'), 47 HB_TAG('i','s','o','l'), 48 HB_TAG('r','l','i','g'), 49 HB_TAG('r','l','i','g'), 50 HB_TAG('r','l','i','g'), 51 }; 52 53 static OT::SubstLookup * 54 arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED, 55 hb_font_t *font, 56 unsigned int feature_index) 57 { 58 OT::HBGlyphID16 glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1]; 59 OT::HBGlyphID16 substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1]; 60 unsigned int num_glyphs = 0; 61 62 /* Populate arrays */ 63 for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++) 64 { 65 hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index]; 66 hb_codepoint_t u_glyph, s_glyph; 67 68 if (!s || 69 !hb_font_get_glyph (font, u, 0, &u_glyph) || 70 !hb_font_get_glyph (font, s, 0, &s_glyph) || 71 u_glyph == s_glyph || 72 u_glyph > 0xFFFFu || s_glyph > 0xFFFFu) 73 continue; 74 75 glyphs[num_glyphs] = u_glyph; 76 substitutes[num_glyphs] = s_glyph; 77 78 num_glyphs++; 79 } 80 81 if (!num_glyphs) 82 return nullptr; 83 84 /* Bubble-sort or something equally good! 85 * May not be good-enough for presidential candidate interviews, but good-enough for us... */ 86 hb_stable_sort (&glyphs[0], num_glyphs, 87 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp, 88 &substitutes[0]); 89 90 91 /* Each glyph takes four bytes max, and there's some overhead. */ 92 char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128]; 93 hb_serialize_context_t c (buf, sizeof (buf)); 94 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> (); 95 bool ret = lookup->serialize_single (&c, 96 OT::LookupFlag::IgnoreMarks, 97 hb_sorted_array (glyphs, num_glyphs), 98 hb_array (substitutes, num_glyphs)); 99 c.end_serialize (); 100 101 return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr; 102 } 103 104 template <typename T> 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 const T &ligature_table, 109 unsigned lookup_flags) 110 { 111 OT::HBGlyphID16 first_glyphs[ARRAY_LENGTH_CONST (ligature_table)]; 112 unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)]; 113 unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)]; 114 unsigned int num_first_glyphs = 0; 115 116 /* We know that all our ligatures have the same number of components. */ 117 OT::HBGlyphID16 ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)]; 118 unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)]; 119 OT::HBGlyphID16 component_list[ARRAY_LENGTH_CONST (ligature_list) * 120 ARRAY_LENGTH_CONST (ligature_table[0].ligatures[0].components)]; 121 unsigned int num_ligatures = 0; 122 unsigned int num_components = 0; 123 124 /* Populate arrays */ 125 126 /* Sort out the first-glyphs */ 127 for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++) 128 { 129 hb_codepoint_t first_u = ligature_table[first_glyph_idx].first; 130 hb_codepoint_t first_glyph; 131 if (!hb_font_get_glyph (font, first_u, 0, &first_glyph)) 132 continue; 133 first_glyphs[num_first_glyphs] = first_glyph; 134 ligature_per_first_glyph_count_list[num_first_glyphs] = 0; 135 first_glyphs_indirection[num_first_glyphs] = first_glyph_idx; 136 num_first_glyphs++; 137 } 138 hb_stable_sort (&first_glyphs[0], num_first_glyphs, 139 (int(*)(const OT::HBUINT16*, const OT::HBUINT16 *)) OT::HBGlyphID16::cmp, 140 &first_glyphs_indirection[0]); 141 142 /* Now that the first-glyphs are sorted, walk again, populate ligatures. */ 143 for (unsigned int i = 0; i < num_first_glyphs; i++) 144 { 145 unsigned int first_glyph_idx = first_glyphs_indirection[i]; 146 147 for (unsigned int ligature_idx = 0; ligature_idx < ARRAY_LENGTH (ligature_table[0].ligatures); ligature_idx++) 148 { 149 hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].ligature; 150 hb_codepoint_t ligature_glyph; 151 if (!hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph)) 152 continue; 153 154 const auto &components = ligature_table[first_glyph_idx].ligatures[ligature_idx].components; 155 unsigned component_count = ARRAY_LENGTH_CONST (components); 156 157 bool matched = true; 158 for (unsigned j = 0; j < component_count; j++) 159 { 160 hb_codepoint_t component_u = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[j]; 161 hb_codepoint_t component_glyph; 162 if (!component_u || 163 !hb_font_get_nominal_glyph (font, component_u, &component_glyph)) 164 { 165 matched = false; 166 break; 167 } 168 169 component_list[num_components++] = component_glyph; 170 } 171 if (!matched) 172 continue; 173 174 component_count_list[num_ligatures] = 1 + component_count; 175 ligature_list[num_ligatures] = ligature_glyph; 176 177 ligature_per_first_glyph_count_list[i]++; 178 179 num_ligatures++; 180 } 181 } 182 183 if (!num_ligatures) 184 return nullptr; 185 186 187 /* 16 bytes per ligature ought to be enough... */ 188 char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128]; 189 hb_serialize_context_t c (buf, sizeof (buf)); 190 OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> (); 191 bool ret = lookup->serialize_ligature (&c, 192 lookup_flags, 193 hb_sorted_array (first_glyphs, num_first_glyphs), 194 hb_array (ligature_per_first_glyph_count_list, num_first_glyphs), 195 hb_array (ligature_list, num_ligatures), 196 hb_array (component_count_list, num_ligatures), 197 hb_array (component_list, num_components)); 198 c.end_serialize (); 199 200 return ret && !c.in_error () ? c.copy<OT::SubstLookup> () : nullptr; 201 } 202 203 static OT::SubstLookup * 204 arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan, 205 hb_font_t *font, 206 unsigned int feature_index) 207 { 208 if (feature_index < 4) 209 return arabic_fallback_synthesize_lookup_single (plan, font, feature_index); 210 else 211 { 212 switch (feature_index) { 213 case 4: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_3_table, OT::LookupFlag::IgnoreMarks); 214 case 5: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_table, OT::LookupFlag::IgnoreMarks); 215 case 6: return arabic_fallback_synthesize_lookup_ligature (plan, font, ligature_mark_table, 0); 216 } 217 } 218 assert (false); 219 return nullptr; 220 } 221 222 #define ARABIC_FALLBACK_MAX_LOOKUPS ARRAY_LENGTH_CONST (arabic_fallback_features) 223 224 struct arabic_fallback_plan_t 225 { 226 unsigned int num_lookups; 227 bool free_lookups; 228 229 hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS]; 230 OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS]; 231 OT::hb_ot_layout_lookup_accelerator_t *accel_array[ARABIC_FALLBACK_MAX_LOOKUPS]; 232 }; 233 234 #if defined(_WIN32) && !defined(HB_NO_WIN1256) 235 #define HB_WITH_WIN1256 236 #endif 237 238 #ifdef HB_WITH_WIN1256 239 #include "hb-ot-shaper-arabic-win1256.hh" 240 #endif 241 242 struct ManifestLookup 243 { 244 public: 245 OT::Tag tag; 246 OT::Offset16To<OT::SubstLookup> lookupOffset; 247 public: 248 DEFINE_SIZE_STATIC (6); 249 }; 250 typedef OT::Array16Of<ManifestLookup> Manifest; 251 252 static bool 253 arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan HB_UNUSED, 254 const hb_ot_shape_plan_t *plan HB_UNUSED, 255 hb_font_t *font HB_UNUSED) 256 { 257 #ifdef HB_WITH_WIN1256 258 /* Does this font look like it's Windows-1256-encoded? */ 259 hb_codepoint_t g; 260 if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ && 261 hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ && 262 hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ && 263 hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ && 264 hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */)) 265 return false; 266 267 const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest); 268 static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) <= 269 ARABIC_FALLBACK_MAX_LOOKUPS * sizeof (ManifestLookup), ""); 270 271 unsigned j = 0; 272 unsigned int count = manifest.len; 273 for (unsigned int i = 0; i < count; i++) 274 { 275 fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag); 276 if (fallback_plan->mask_array[j]) 277 { 278 fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset)); 279 if (fallback_plan->lookup_array[j]) 280 { 281 fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]); 282 j++; 283 } 284 } 285 } 286 287 fallback_plan->num_lookups = j; 288 fallback_plan->free_lookups = false; 289 290 return j > 0; 291 #else 292 return false; 293 #endif 294 } 295 296 static bool 297 arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan, 298 const hb_ot_shape_plan_t *plan, 299 hb_font_t *font) 300 { 301 static_assert ((ARRAY_LENGTH_CONST (arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), ""); 302 unsigned int j = 0; 303 for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++) 304 { 305 fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]); 306 if (fallback_plan->mask_array[j]) 307 { 308 fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i); 309 if (fallback_plan->lookup_array[j]) 310 { 311 fallback_plan->accel_array[j] = OT::hb_ot_layout_lookup_accelerator_t::create (*fallback_plan->lookup_array[j]); 312 j++; 313 } 314 } 315 } 316 317 fallback_plan->num_lookups = j; 318 fallback_plan->free_lookups = true; 319 320 return j > 0; 321 } 322 323 static arabic_fallback_plan_t * 324 arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan, 325 hb_font_t *font) 326 { 327 arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_calloc (1, sizeof (arabic_fallback_plan_t)); 328 if (unlikely (!fallback_plan)) 329 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t)); 330 331 fallback_plan->num_lookups = 0; 332 fallback_plan->free_lookups = false; 333 334 /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms, 335 * in case the font has cmap entries for the presentation-forms characters. */ 336 if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font)) 337 return fallback_plan; 338 339 /* See if this looks like a Windows-1256-encoded font. If it does, use a 340 * hand-coded GSUB table. */ 341 if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font)) 342 return fallback_plan; 343 344 assert (fallback_plan->num_lookups == 0); 345 hb_free (fallback_plan); 346 return const_cast<arabic_fallback_plan_t *> (&Null (arabic_fallback_plan_t)); 347 } 348 349 static void 350 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan) 351 { 352 if (!fallback_plan || fallback_plan->num_lookups == 0) 353 return; 354 355 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++) 356 if (fallback_plan->lookup_array[i]) 357 { 358 if (fallback_plan->accel_array[i]) 359 fallback_plan->accel_array[i]->fini (); 360 hb_free (fallback_plan->accel_array[i]); 361 if (fallback_plan->free_lookups) 362 hb_free (fallback_plan->lookup_array[i]); 363 } 364 365 hb_free (fallback_plan); 366 } 367 368 static void 369 arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan, 370 hb_font_t *font, 371 hb_buffer_t *buffer) 372 { 373 OT::hb_ot_apply_context_t c (0, font, buffer, hb_blob_get_empty ()); 374 for (unsigned int i = 0; i < fallback_plan->num_lookups; i++) 375 if (fallback_plan->lookup_array[i]) { 376 c.set_lookup_mask (fallback_plan->mask_array[i]); 377 if (fallback_plan->accel_array[i]) 378 hb_ot_layout_substitute_lookup (&c, 379 *fallback_plan->lookup_array[i], 380 *fallback_plan->accel_array[i]); 381 } 382 } 383 384 385 #endif /* HB_OT_SHAPER_ARABIC_FALLBACK_HH */