hb-ot-shape-complex-thai.cc revision 127daf15e0b2f509ebd29a104236c8b38884efb0
1/* 2 * Copyright © 2010,2012 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-ot-shape-complex-private.hh" 28 29 30/* Thai / Lao shaper */ 31 32 33/* PUA shaping */ 34 35 36enum thai_consonant_type_t 37{ 38 NC, 39 AC, 40 RC, 41 DC, 42 NOT_CONSONANT, 43 NUM_CONSONANT_TYPES = NOT_CONSONANT 44}; 45 46static thai_consonant_type_t 47get_consonant_type (hb_codepoint_t u) 48{ 49 if (u == 0x0E1B || u == 0x0E1D || u == 0x0E1F/* || u == 0x0E2C*/) 50 return AC; 51 if (u == 0x0E0D || u == 0x0E10) 52 return RC; 53 if (u == 0x0E0E || u == 0x0E0F) 54 return DC; 55 if (hb_in_range<hb_codepoint_t> (u, 0x0E01, 0x0E2E)) 56 return NC; 57 return NOT_CONSONANT; 58} 59 60 61enum thai_mark_type_t 62{ 63 AV, 64 BV, 65 T, 66 NOT_MARK, 67 NUM_MARK_TYPES = NOT_MARK 68}; 69 70static thai_mark_type_t 71get_mark_type (hb_codepoint_t u) 72{ 73 if (u == 0x0E31 || hb_in_range<hb_codepoint_t> (u, 0x0E34, 0x0E37) || 74 u == 0x0E47 || hb_in_range<hb_codepoint_t> (u, 0x0E4D, 0x0E4E)) 75 return AV; 76 if (hb_in_range<hb_codepoint_t> (u, 0x0E38, 0x0E3A)) 77 return BV; 78 if (hb_in_range<hb_codepoint_t> (u, 0x0E48, 0x0E4C)) 79 return T; 80 return NOT_MARK; 81} 82 83 84enum thai_action_t 85{ 86 NOP, 87 SD, /* Shift combining-mark down */ 88 SL, /* Shift combining-mark left */ 89 SDL, /* Shift combining-mark down-left */ 90 RD /* Remove descender from base */ 91}; 92 93static hb_codepoint_t 94thai_pua_shape (hb_codepoint_t u, thai_action_t action, hb_font_t *font) 95{ 96 struct thai_pua_mapping_t { 97 hb_codepoint_t u; 98 hb_codepoint_t win_pua; 99 hb_codepoint_t mac_pua; 100 } const *pua_mappings = NULL; 101 static const thai_pua_mapping_t SD_mappings[] = { 102 {0x0E48, 0xF70A, 0xF88B}, /* MAI EK */ 103 {0x0E49, 0xF70B, 0xF88E}, /* MAI THO */ 104 {0x0E4A, 0xF70C, 0xF891}, /* MAI TRI */ 105 {0x0E4B, 0xF70D, 0xF894}, /* MAI CHATTAWA */ 106 {0x0E4C, 0xF70E, 0xF897}, /* THANTHAKHAT */ 107 {0x0E38, 0xF718, 0xF89B}, /* SARA U */ 108 {0x0E39, 0xF719, 0xF89C}, /* SARA UU */ 109 {0x0E3A, 0xF71A, 0xF89D}, /* PHINTHU */ 110 {0x0000, 0x0000, 0x0000} 111 }; 112 static const thai_pua_mapping_t SDL_mappings[] = { 113 {0x0E48, 0xF705, 0xF88C}, /* MAI EK */ 114 {0x0E49, 0xF706, 0xF88F}, /* MAI THO */ 115 {0x0E4A, 0xF707, 0xF892}, /* MAI TRI */ 116 {0x0E4B, 0xF708, 0xF895}, /* MAI CHATTAWA */ 117 {0x0E4C, 0xF709, 0xF898}, /* THANTHAKHAT */ 118 {0x0000, 0x0000, 0x0000} 119 }; 120 static const thai_pua_mapping_t SL_mappings[] = { 121 {0x0E48, 0xF713, 0xF88A}, /* MAI EK */ 122 {0x0E49, 0xF714, 0xF88D}, /* MAI THO */ 123 {0x0E4A, 0xF715, 0xF890}, /* MAI TRI */ 124 {0x0E4B, 0xF716, 0xF893}, /* MAI CHATTAWA */ 125 {0x0E4C, 0xF717, 0xF896}, /* THANTHAKHAT */ 126 {0x0E31, 0xF710, 0xF884}, /* MAI HAN-AKAT */ 127 {0x0E34, 0xF701, 0xF885}, /* SARA I */ 128 {0x0E35, 0xF702, 0xF886}, /* SARA II */ 129 {0x0E36, 0xF703, 0xF887}, /* SARA UE */ 130 {0x0E37, 0xF704, 0xF888}, /* SARA UEE */ 131 {0x0E47, 0xF712, 0xF889}, /* MAITAIKHU */ 132 {0x0E4D, 0xF711, 0xF899}, /* NIKHAHIT */ 133 {0x0000, 0x0000, 0x0000} 134 }; 135 static const thai_pua_mapping_t RD_mappings[] = { 136 {0x0E0D, 0xF70F, 0xF89A}, /* YO YING */ 137 {0x0E10, 0xF700, 0xF89E}, /* THO THAN */ 138 {0x0000, 0x0000, 0x0000} 139 }; 140 141 switch (action) { 142 default: assert (false); /* Fallthrough */ 143 case NOP: return u; 144 case SD: pua_mappings = SD_mappings; break; 145 case SDL: pua_mappings = SDL_mappings; break; 146 case SL: pua_mappings = SL_mappings; break; 147 case RD: pua_mappings = RD_mappings; break; 148 } 149 for (; pua_mappings->u; pua_mappings++) 150 if (pua_mappings->u == u) 151 { 152 hb_codepoint_t glyph; 153 if (hb_font_get_glyph (font, pua_mappings->win_pua, 0, &glyph)) 154 return pua_mappings->win_pua; 155 if (hb_font_get_glyph (font, pua_mappings->mac_pua, 0, &glyph)) 156 return pua_mappings->mac_pua; 157 break; 158 } 159 return u; 160} 161 162 163static enum thai_above_state_t 164{ /* Cluster above looks like: */ 165 T0, /* ⣤ */ 166 T1, /* ⣼ */ 167 T2, /* ⣾ */ 168 T3, /* ⣿ */ 169 NUM_ABOVE_STATES 170} thai_above_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] = 171{ 172 T0, /* NC */ 173 T1, /* AC */ 174 T0, /* RC */ 175 T0, /* DC */ 176 T3, /* NOT_CONSONANT */ 177}; 178 179static const struct thai_above_state_machine_edge_t { 180 thai_action_t action; 181 thai_above_state_t next_state; 182} thai_above_state_machine[NUM_ABOVE_STATES][NUM_MARK_TYPES] = 183{ /*AV*/ /*BV*/ /*T*/ 184/*T0*/ {{NOP,T3}, {NOP,T0}, {SD, T3}}, 185/*T1*/ {{SL, T2}, {NOP,T1}, {SDL,T2}}, 186/*T2*/ {{NOP,T3}, {NOP,T2}, {SL, T3}}, 187/*T3*/ {{NOP,T3}, {NOP,T3}, {NOP,T3}}, 188}; 189 190 191static enum thai_below_state_t 192{ 193 B0, /* No descender */ 194 B1, /* Removable descender */ 195 B2, /* Strict descender */ 196 NUM_BELOW_STATES 197} thai_below_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] = 198{ 199 B0, /* NC */ 200 B0, /* AC */ 201 B1, /* RC */ 202 B2, /* DC */ 203 B2, /* NOT_CONSONANT */ 204}; 205 206static const struct thai_below_state_machine_edge_t { 207 thai_action_t action; 208 thai_below_state_t next_state; 209} thai_below_state_machine[NUM_BELOW_STATES][NUM_MARK_TYPES] = 210{ /*AV*/ /*BV*/ /*T*/ 211/*B0*/ {{NOP,B0}, {NOP,B2}, {NOP, B0}}, 212/*B1*/ {{NOP,B1}, {RD, B2}, {NOP, B1}}, 213/*B2*/ {{NOP,B2}, {SD, B2}, {NOP, B2}}, 214}; 215 216 217static void 218do_thai_pua_shaping (const hb_ot_shape_plan_t *plan HB_UNUSED, 219 hb_buffer_t *buffer, 220 hb_font_t *font) 221{ 222 thai_above_state_t above_state = thai_above_start_state[NOT_CONSONANT]; 223 thai_below_state_t below_state = thai_below_start_state[NOT_CONSONANT]; 224 unsigned int base = 0; 225 226 hb_glyph_info_t *info = buffer->info; 227 unsigned int count = buffer->len; 228 for (unsigned int i = 0; i < count; i++) 229 { 230 thai_mark_type_t mt = get_mark_type (info[i].codepoint); 231 232 if (mt == NOT_MARK) { 233 thai_consonant_type_t ct = get_consonant_type (info[i].codepoint); 234 above_state = thai_above_start_state[ct]; 235 below_state = thai_below_start_state[ct]; 236 base = i; 237 continue; 238 } 239 240 const thai_above_state_machine_edge_t &above_edge = thai_above_state_machine[above_state][mt]; 241 const thai_below_state_machine_edge_t &below_edge = thai_below_state_machine[below_state][mt]; 242 above_state = above_edge.next_state; 243 below_state = below_edge.next_state; 244 245 /* At least one of the above/below actions is NOP. */ 246 thai_action_t action = above_edge.action != NOP ? above_edge.action : below_edge.action; 247 248 if (action == RD) 249 info[base].codepoint = thai_pua_shape (info[base].codepoint, action, font); 250 else 251 info[i].codepoint = thai_pua_shape (info[i].codepoint, action, font); 252 } 253} 254 255 256static void 257preprocess_text_thai (const hb_ot_shape_plan_t *plan, 258 hb_buffer_t *buffer, 259 hb_font_t *font) 260{ 261 /* This function implements the shaping logic documented here: 262 * 263 * http://linux.thai.net/~thep/th-otf/shaping.html 264 * 265 * The first shaping rule listed there is needed even if the font has Thai 266 * OpenType tables. The rest do fallback positioning based on PUA codepoints. 267 * We implement that only if there exist no Thai GSUB in the font. 268 */ 269 270 /* The following is NOT specified in the MS OT Thai spec, however, it seems 271 * to be what Uniscribe and other engines implement. According to Eric Muller: 272 * 273 * When you have a SARA AM, decompose it in NIKHAHIT + SARA AA, *and* move the 274 * NIKHAHIT backwards over any tone mark (0E48-0E4B). 275 * 276 * <0E14, 0E4B, 0E33> -> <0E14, 0E4D, 0E4B, 0E32> 277 * 278 * This reordering is legit only when the NIKHAHIT comes from a SARA AM, not 279 * when it's there to start with. The string <0E14, 0E4B, 0E4D> is probably 280 * not what a user wanted, but the rendering is nevertheless nikhahit above 281 * chattawa. 282 * 283 * Same for Lao. 284 * 285 * Note: 286 * 287 * Uniscribe also does some below-marks reordering. Namely, it positions U+0E3A 288 * after U+0E38 and U+0E39. We do that by modifying the ccc for U+0E3A. 289 * See unicode->modified_combining_class (). Lao does NOT have a U+0E3A 290 * equivalent. 291 */ 292 293 294 /* 295 * Here are the characters of significance: 296 * 297 * Thai Lao 298 * SARA AM: U+0E33 U+0EB3 299 * SARA AA: U+0E32 U+0EB2 300 * Nikhahit: U+0E4D U+0ECD 301 * 302 * Testing shows that Uniscribe reorder the following marks: 303 * Thai: <0E31,0E34..0E37,0E47..0E4E> 304 * Lao: <0EB1,0EB4..0EB7,0EC7..0ECE> 305 * 306 * Note how the Lao versions are the same as Thai + 0x80. 307 */ 308 309 /* We only get one script at a time, so a script-agnostic implementation 310 * is adequate here. */ 311#define IS_SARA_AM(x) (((x) & ~0x0080) == 0x0E33) 312#define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0xE33 + 0xE4D) 313#define SARA_AA_FROM_SARA_AM(x) ((x) - 1) 314#define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080, 0x0E34, 0x0E37, 0x0E47, 0x0E4E, 0x0E31, 0x0E31)) 315 316 buffer->clear_output (); 317 unsigned int count = buffer->len; 318 for (buffer->idx = 0; buffer->idx < count;) 319 { 320 hb_codepoint_t u = buffer->cur().codepoint; 321 if (likely (!IS_SARA_AM (u))) { 322 buffer->next_glyph (); 323 continue; 324 } 325 326 /* Is SARA AM. Decompose and reorder. */ 327 hb_codepoint_t decomposed[2] = {hb_codepoint_t (NIKHAHIT_FROM_SARA_AM (u)), 328 hb_codepoint_t (SARA_AA_FROM_SARA_AM (u))}; 329 buffer->replace_glyphs (1, 2, decomposed); 330 if (unlikely (buffer->in_error)) 331 return; 332 333 /* Ok, let's see... */ 334 unsigned int end = buffer->out_len; 335 unsigned int start = end - 2; 336 while (start > 0 && IS_TONE_MARK (buffer->out_info[start - 1].codepoint)) 337 start--; 338 339 if (start + 2 < end) 340 { 341 /* Move Nikhahit (end-2) to the beginning */ 342 buffer->merge_out_clusters (start, end); 343 hb_glyph_info_t t = buffer->out_info[end - 2]; 344 memmove (buffer->out_info + start + 1, 345 buffer->out_info + start, 346 sizeof (buffer->out_info[0]) * (end - start - 2)); 347 buffer->out_info[start] = t; 348 } 349 else 350 { 351 /* Since we decomposed, and NIKHAHIT is combining, merge clusters with the 352 * previous cluster. */ 353 if (start) 354 buffer->merge_out_clusters (start - 1, end); 355 } 356 } 357 buffer->swap_buffers (); 358 359 /* If font has Thai GSUB, we are done. */ 360 if (plan->props.script == HB_SCRIPT_THAI && !plan->map.found_script[0]) 361 do_thai_pua_shaping (plan, buffer, font); 362} 363 364const hb_ot_complex_shaper_t _hb_ot_complex_shaper_thai = 365{ 366 "thai", 367 NULL, /* collect_features */ 368 NULL, /* override_features */ 369 NULL, /* data_create */ 370 NULL, /* data_destroy */ 371 preprocess_text_thai, 372 NULL, /* normalization_preference */ 373 NULL, /* decompose */ 374 NULL, /* compose */ 375 NULL, /* setup_masks */ 376 HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_LATE, 377 false,/* fallback_position */ 378}; 379