hb-ot-shaper-khmer.cc (10865B)
1 /* 2 * Copyright © 2011,2012 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 #include "hb.hh" 28 29 #ifndef HB_NO_OT_SHAPE 30 31 #include "hb-ot-shaper-khmer-machine.hh" 32 #include "hb-ot-shaper-indic.hh" 33 #include "hb-ot-layout.hh" 34 35 36 /* 37 * Khmer shaper. 38 */ 39 40 41 static const hb_ot_map_feature_t 42 khmer_features[] = 43 { 44 /* 45 * Basic features. 46 * These features are applied all at once, before reordering, constrained 47 * to the syllable. 48 */ 49 {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE}, 50 {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE}, 51 {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE}, 52 {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE}, 53 {HB_TAG('c','f','a','r'), F_MANUAL_JOINERS | F_PER_SYLLABLE}, 54 /* 55 * Other features. 56 * These features are applied all at once after clearing syllables. 57 */ 58 {HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS}, 59 {HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS}, 60 {HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS}, 61 {HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS}, 62 }; 63 64 /* 65 * Must be in the same order as the khmer_features array. 66 */ 67 enum { 68 KHMER_PREF, 69 KHMER_BLWF, 70 KHMER_ABVF, 71 KHMER_PSTF, 72 KHMER_CFAR, 73 74 _KHMER_PRES, 75 _KHMER_ABVS, 76 _KHMER_BLWS, 77 _KHMER_PSTS, 78 79 KHMER_NUM_FEATURES, 80 KHMER_BASIC_FEATURES = _KHMER_PRES, /* Don't forget to update this! */ 81 }; 82 83 static inline void 84 set_khmer_properties (hb_glyph_info_t &info) 85 { 86 hb_codepoint_t u = info.codepoint; 87 unsigned int type = hb_indic_get_categories (u); 88 89 info.khmer_category() = (khmer_category_t) (type & 0xFFu); 90 } 91 92 static bool 93 setup_syllables_khmer (const hb_ot_shape_plan_t *plan, 94 hb_font_t *font, 95 hb_buffer_t *buffer); 96 static bool 97 reorder_khmer (const hb_ot_shape_plan_t *plan, 98 hb_font_t *font, 99 hb_buffer_t *buffer); 100 101 static void 102 collect_features_khmer (hb_ot_shape_planner_t *plan) 103 { 104 hb_ot_map_builder_t *map = &plan->map; 105 106 /* Do this before any lookups have been applied. */ 107 map->add_gsub_pause (setup_syllables_khmer); 108 map->add_gsub_pause (reorder_khmer); 109 110 /* Testing suggests that Uniscribe does NOT pause between basic 111 * features. Test with KhmerUI.ttf and the following three 112 * sequences: 113 * 114 * U+1789,U+17BC 115 * U+1789,U+17D2,U+1789 116 * U+1789,U+17D2,U+1789,U+17BC 117 * 118 * https://github.com/harfbuzz/harfbuzz/issues/974 119 */ 120 map->enable_feature (HB_TAG('l','o','c','l'), F_PER_SYLLABLE); 121 map->enable_feature (HB_TAG('c','c','m','p'), F_PER_SYLLABLE); 122 123 unsigned int i = 0; 124 for (; i < KHMER_BASIC_FEATURES; i++) 125 map->add_feature (khmer_features[i]); 126 127 /* https://github.com/harfbuzz/harfbuzz/issues/3531 */ 128 map->add_gsub_pause (hb_syllabic_clear_var); // Don't need syllables anymore, use stop to free buffer var 129 130 for (; i < KHMER_NUM_FEATURES; i++) 131 map->add_feature (khmer_features[i]); 132 } 133 134 static void 135 override_features_khmer (hb_ot_shape_planner_t *plan) 136 { 137 hb_ot_map_builder_t *map = &plan->map; 138 139 /* Khmer spec has 'clig' as part of required shaping features: 140 * "Apply feature 'clig' to form ligatures that are desired for 141 * typographical correctness.", hence in overrides... */ 142 map->enable_feature (HB_TAG('c','l','i','g')); 143 144 map->disable_feature (HB_TAG('l','i','g','a')); 145 } 146 147 148 struct khmer_shape_plan_t 149 { 150 hb_mask_t mask_array[KHMER_NUM_FEATURES]; 151 }; 152 153 static void * 154 data_create_khmer (const hb_ot_shape_plan_t *plan) 155 { 156 khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) hb_calloc (1, sizeof (khmer_shape_plan_t)); 157 if (unlikely (!khmer_plan)) 158 return nullptr; 159 160 for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++) 161 khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ? 162 0 : plan->map.get_1_mask (khmer_features[i].tag); 163 164 return khmer_plan; 165 } 166 167 static void 168 data_destroy_khmer (void *data) 169 { 170 hb_free (data); 171 } 172 173 static void 174 setup_masks_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED, 175 hb_buffer_t *buffer, 176 hb_font_t *font HB_UNUSED) 177 { 178 HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category); 179 180 /* We cannot setup masks here. We save information about characters 181 * and setup masks later on in a pause-callback. */ 182 183 unsigned int count = buffer->len; 184 hb_glyph_info_t *info = buffer->info; 185 for (unsigned int i = 0; i < count; i++) 186 set_khmer_properties (info[i]); 187 } 188 189 static bool 190 setup_syllables_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED, 191 hb_font_t *font HB_UNUSED, 192 hb_buffer_t *buffer) 193 { 194 HB_BUFFER_ALLOCATE_VAR (buffer, syllable); 195 find_syllables_khmer (buffer); 196 foreach_syllable (buffer, start, end) 197 buffer->unsafe_to_break (start, end); 198 return false; 199 } 200 201 202 /* Rules from: 203 * https://docs.microsoft.com/en-us/typography/script-development/devanagari */ 204 205 static void 206 reorder_consonant_syllable (const hb_ot_shape_plan_t *plan, 207 hb_face_t *face HB_UNUSED, 208 hb_buffer_t *buffer, 209 unsigned int start, unsigned int end) 210 { 211 const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data; 212 hb_glyph_info_t *info = buffer->info; 213 214 /* Setup masks. */ 215 { 216 /* Post-base */ 217 hb_mask_t mask = khmer_plan->mask_array[KHMER_BLWF] | 218 khmer_plan->mask_array[KHMER_ABVF] | 219 khmer_plan->mask_array[KHMER_PSTF]; 220 for (unsigned int i = start + 1; i < end; i++) 221 info[i].mask |= mask; 222 } 223 224 unsigned int num_coengs = 0; 225 for (unsigned int i = start + 1; i < end; i++) 226 { 227 /* """ 228 * When a COENG + (Cons | IndV) combination are found (and subscript count 229 * is less than two) the character combination is handled according to the 230 * subscript type of the character following the COENG. 231 * 232 * ... 233 * 234 * Subscript Type 2 - The COENG + RO characters are reordered to immediately 235 * before the base glyph. Then the COENG + RO characters are assigned to have 236 * the 'pref' OpenType feature applied to them. 237 * """ 238 */ 239 if (info[i].khmer_category() == K_Cat(H) && num_coengs <= 2 && i + 1 < end) 240 { 241 num_coengs++; 242 243 if (info[i + 1].khmer_category() == K_Cat(Ra)) 244 { 245 for (unsigned int j = 0; j < 2; j++) 246 info[i + j].mask |= khmer_plan->mask_array[KHMER_PREF]; 247 248 /* Move the Coeng,Ro sequence to the start. */ 249 buffer->merge_clusters (start, i + 2); 250 hb_glyph_info_t t0 = info[i]; 251 hb_glyph_info_t t1 = info[i + 1]; 252 memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0])); 253 info[start] = t0; 254 info[start + 1] = t1; 255 256 /* Mark the subsequent stuff with 'cfar'. Used in Khmer. 257 * Read the feature spec. 258 * This allows distinguishing the following cases with MS Khmer fonts: 259 * U+1784,U+17D2,U+179A,U+17D2,U+1782 260 * U+1784,U+17D2,U+1782,U+17D2,U+179A 261 */ 262 if (khmer_plan->mask_array[KHMER_CFAR]) 263 for (unsigned int j = i + 2; j < end; j++) 264 info[j].mask |= khmer_plan->mask_array[KHMER_CFAR]; 265 266 num_coengs = 2; /* Done. */ 267 } 268 } 269 270 /* Reorder left matra piece. */ 271 else if (info[i].khmer_category() == K_Cat(VPre)) 272 { 273 /* Move to the start. */ 274 buffer->merge_clusters (start, i + 1); 275 hb_glyph_info_t t = info[i]; 276 memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0])); 277 info[start] = t; 278 } 279 } 280 } 281 282 static void 283 reorder_syllable_khmer (const hb_ot_shape_plan_t *plan, 284 hb_face_t *face, 285 hb_buffer_t *buffer, 286 unsigned int start, unsigned int end) 287 { 288 khmer_syllable_type_t syllable_type = (khmer_syllable_type_t) (buffer->info[start].syllable() & 0x0F); 289 switch (syllable_type) 290 { 291 case khmer_broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */ 292 case khmer_consonant_syllable: 293 reorder_consonant_syllable (plan, face, buffer, start, end); 294 break; 295 296 case khmer_non_khmer_cluster: 297 break; 298 } 299 } 300 301 static bool 302 reorder_khmer (const hb_ot_shape_plan_t *plan, 303 hb_font_t *font, 304 hb_buffer_t *buffer) 305 { 306 bool ret = false; 307 if (buffer->message (font, "start reordering khmer")) 308 { 309 if (hb_syllabic_insert_dotted_circles (font, buffer, 310 khmer_broken_cluster, 311 K_Cat(DOTTEDCIRCLE), 312 (unsigned) -1)) 313 ret = true; 314 315 foreach_syllable (buffer, start, end) 316 reorder_syllable_khmer (plan, font->face, buffer, start, end); 317 (void) buffer->message (font, "end reordering khmer"); 318 } 319 HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category); 320 321 return ret; 322 } 323 324 325 static bool 326 decompose_khmer (const hb_ot_shape_normalize_context_t *c, 327 hb_codepoint_t ab, 328 hb_codepoint_t *a, 329 hb_codepoint_t *b) 330 { 331 switch (ab) 332 { 333 /* 334 * Decompose split matras that don't have Unicode decompositions. 335 */ 336 337 /* Khmer */ 338 case 0x17BEu : *a = 0x17C1u; *b= 0x17BEu; return true; 339 case 0x17BFu : *a = 0x17C1u; *b= 0x17BFu; return true; 340 case 0x17C0u : *a = 0x17C1u; *b= 0x17C0u; return true; 341 case 0x17C4u : *a = 0x17C1u; *b= 0x17C4u; return true; 342 case 0x17C5u : *a = 0x17C1u; *b= 0x17C5u; return true; 343 } 344 345 return (bool) c->unicode->decompose (ab, a, b); 346 } 347 348 static bool 349 compose_khmer (const hb_ot_shape_normalize_context_t *c, 350 hb_codepoint_t a, 351 hb_codepoint_t b, 352 hb_codepoint_t *ab) 353 { 354 /* Avoid recomposing split matras. */ 355 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a))) 356 return false; 357 358 return (bool) c->unicode->compose (a, b, ab); 359 } 360 361 362 const hb_ot_shaper_t _hb_ot_shaper_khmer = 363 { 364 collect_features_khmer, 365 override_features_khmer, 366 data_create_khmer, 367 data_destroy_khmer, 368 nullptr, /* preprocess_text */ 369 nullptr, /* postprocess_glyphs */ 370 decompose_khmer, 371 compose_khmer, 372 setup_masks_khmer, 373 nullptr, /* reorder_marks */ 374 HB_TAG_NONE, /* gpos_tag */ 375 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT, 376 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE, 377 false, /* fallback_position */ 378 }; 379 380 381 #endif