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-ot-shape-complex-indic-private.hh"
28 #include "hb-ot-layout-private.hh"
29
30
31 /*
32 * Indic shaper.
33 */
34
35
36 /*
37 * Indic configurations. Note that we do not want to keep every single script-specific
38 * behavior in these tables necessarily. This should mainly be used for per-script
39 * properties that are cheaper keeping here, than in the code. Ie. if, say, one and
40 * only one script has an exception, that one script can be if'ed directly in the code,
41 * instead of adding a new flag in these structs.
42 */
43
44 enum base_position_t {
45 BASE_POS_LAST_SINHALA,
46 BASE_POS_LAST
47 };
48 enum reph_position_t {
49 REPH_POS_AFTER_MAIN = POS_AFTER_MAIN,
50 REPH_POS_BEFORE_SUB = POS_BEFORE_SUB,
51 REPH_POS_AFTER_SUB = POS_AFTER_SUB,
52 REPH_POS_BEFORE_POST = POS_BEFORE_POST,
53 REPH_POS_AFTER_POST = POS_AFTER_POST
54 };
55 enum reph_mode_t {
56 REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */
57 REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */
58 REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */
59 };
60 enum blwf_mode_t {
61 BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
62 BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */
63 };
64 struct indic_config_t
65 {
66 hb_script_t script;
67 bool has_old_spec;
68 hb_codepoint_t virama;
69 base_position_t base_pos;
70 reph_position_t reph_pos;
71 reph_mode_t reph_mode;
72 blwf_mode_t blwf_mode;
73 };
74
75 static const indic_config_t indic_configs[] =
76 {
77 /* Default. Should be first. */
78 {HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
79 {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
80 {HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
81 {HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
82 {HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
83 {HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
84 {HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
85 {HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
86 {HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
87 {HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
88 {HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA,
89 REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
90 };
91
92
93
94 /*
95 * Indic shaper.
96 */
97
98 struct feature_list_t {
99 hb_tag_t tag;
100 hb_ot_map_feature_flags_t flags;
101 };
102
103 static const feature_list_t
104 indic_features[] =
105 {
106 /*
107 * Basic features.
108 * These features are applied in order, one at a time, after initial_reordering.
109 */
110 {HB_TAG('n','u','k','t'), F_GLOBAL},
111 {HB_TAG('a','k','h','n'), F_GLOBAL},
112 {HB_TAG('r','p','h','f'), F_NONE},
113 {HB_TAG('r','k','r','f'), F_GLOBAL},
114 {HB_TAG('p','r','e','f'), F_NONE},
115 {HB_TAG('b','l','w','f'), F_NONE},
116 {HB_TAG('a','b','v','f'), F_NONE},
117 {HB_TAG('h','a','l','f'), F_NONE},
118 {HB_TAG('p','s','t','f'), F_NONE},
119 {HB_TAG('v','a','t','u'), F_GLOBAL},
120 {HB_TAG('c','j','c','t'), F_GLOBAL},
121 /*
122 * Other features.
123 * These features are applied all at once, after final_reordering.
124 * Default Bengali font in Windows for example has intermixed
125 * lookups for init,pres,abvs,blws features.
126 */
127 {HB_TAG('i','n','i','t'), F_NONE},
128 {HB_TAG('p','r','e','s'), F_GLOBAL},
129 {HB_TAG('a','b','v','s'), F_GLOBAL},
130 {HB_TAG('b','l','w','s'), F_GLOBAL},
131 {HB_TAG('p','s','t','s'), F_GLOBAL},
132 {HB_TAG('h','a','l','n'), F_GLOBAL},
133 /* Positioning features, though we don't care about the types. */
134 {HB_TAG('d','i','s','t'), F_GLOBAL},
135 {HB_TAG('a','b','v','m'), F_GLOBAL},
136 {HB_TAG('b','l','w','m'), F_GLOBAL},
137 };
138
139 /*
140 * Must be in the same order as the indic_features array.
141 */
142 enum {
143 _NUKT,
144 _AKHN,
145 RPHF,
146 _RKRF,
147 PREF,
148 BLWF,
149 ABVF,
150 HALF,
151 PSTF,
152 _VATU,
153 _CJCT,
154
155 INIT,
156 _PRES,
157 _ABVS,
158 _BLWS,
159 _PSTS,
160 _HALN,
161 _DIST,
162 _ABVM,
163 _BLWM,
164
165 INDIC_NUM_FEATURES,
166 INDIC_BASIC_FEATURES = INIT /* Don't forget to update this! */
167 };
168
169 static void
170 setup_syllables (const hb_ot_shape_plan_t *plan,
171 hb_font_t *font,
172 hb_buffer_t *buffer);
173 static void
174 initial_reordering (const hb_ot_shape_plan_t *plan,
175 hb_font_t *font,
176 hb_buffer_t *buffer);
177 static void
178 final_reordering (const hb_ot_shape_plan_t *plan,
179 hb_font_t *font,
180 hb_buffer_t *buffer);
181 static void
182 clear_syllables (const hb_ot_shape_plan_t *plan,
183 hb_font_t *font,
184 hb_buffer_t *buffer);
185
186 static void
187 collect_features_indic (hb_ot_shape_planner_t *plan)
188 {
189 hb_ot_map_builder_t *map = &plan->map;
190
191 /* Do this before any lookups have been applied. */
192 map->add_gsub_pause (setup_syllables);
193
194 map->add_global_bool_feature (HB_TAG('l','o','c','l'));
195 /* The Indic specs do not require ccmp, but we apply it here since if
196 * there is a use of it, it's typically at the beginning. */
197 map->add_global_bool_feature (HB_TAG('c','c','m','p'));
198
199
200 unsigned int i = 0;
201 map->add_gsub_pause (initial_reordering);
202 for (; i < INDIC_BASIC_FEATURES; i++) {
203 map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
204 map->add_gsub_pause (nullptr);
205 }
206 map->add_gsub_pause (final_reordering);
207 for (; i < INDIC_NUM_FEATURES; i++) {
208 map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
209 }
210
211 map->add_global_bool_feature (HB_TAG('c','a','l','t'));
212 map->add_global_bool_feature (HB_TAG('c','l','i','g'));
213
214 map->add_gsub_pause (clear_syllables);
215 }
216
217 static void
218 override_features_indic (hb_ot_shape_planner_t *plan)
219 {
220 plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);
221 }
222
223
224 struct would_substitute_feature_t
225 {
226 inline void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
227 {
228 zero_context = zero_context_;
229 map->get_stage_lookups (0/*GSUB*/,
230 map->get_feature_stage (0/*GSUB*/, feature_tag),
231 &lookups, &count);
232 }
233
234 inline bool would_substitute (const hb_codepoint_t *glyphs,
235 unsigned int glyphs_count,
236 hb_face_t *face) const
237 {
238 for (unsigned int i = 0; i < count; i++)
239 if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
240 return true;
241 return false;
242 }
243
244 private:
245 const hb_ot_map_t::lookup_map_t *lookups;
246 unsigned int count;
247 bool zero_context;
248 };
249
250 struct indic_shape_plan_t
251 {
252 ASSERT_POD ();
253
254 inline bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
255 {
256 hb_codepoint_t glyph = virama_glyph;
257 if (unlikely (virama_glyph == (hb_codepoint_t) -1))
258 {
259 if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
260 glyph = 0;
261 /* Technically speaking, the spec says we should apply 'locl' to virama too.
262 * Maybe one day... */
263
264 /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
265 * during shape planning... Instead, overwrite it here. It's safe. Don't worry! */
266 virama_glyph = glyph;
267 }
268
269 *pglyph = glyph;
270 return glyph != 0;
271 }
272
273 const indic_config_t *config;
274
275 bool is_old_spec;
276 mutable hb_codepoint_t virama_glyph;
277
278 would_substitute_feature_t rphf;
279 would_substitute_feature_t pref;
280 would_substitute_feature_t blwf;
281 would_substitute_feature_t pstf;
282
283 hb_mask_t mask_array[INDIC_NUM_FEATURES];
284 };
285
286 static void *
287 data_create_indic (const hb_ot_shape_plan_t *plan)
288 {
289 indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
290 if (unlikely (!indic_plan))
291 return nullptr;
292
293 indic_plan->config = &indic_configs[0];
294 for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
295 if (plan->props.script == indic_configs[i].script) {
296 indic_plan->config = &indic_configs[i];
297 break;
298 }
299
300 indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
301 indic_plan->virama_glyph = (hb_codepoint_t) -1;
302
303 /* Use zero-context would_substitute() matching for new-spec of the main
304 * Indic scripts, and scripts with one spec only, but not for old-specs.
305 * The new-spec for all dual-spec scripts says zero-context matching happens.
306 *
307 * However, testing with Malayalam shows that old and new spec both allow
308 * context. Testing with Bengali new-spec however shows that it doesn't.
309 * So, the heuristic here is the way it is. It should *only* be changed,
310 * as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE.
311 */
312 bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
313 indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
314 indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
315 indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
316 indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
317
318 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
319 indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
320 0 : plan->map.get_1_mask (indic_features[i].tag);
321
322 return indic_plan;
323 }
324
325 static void
326 data_destroy_indic (void *data)
327 {
328 free (data);
329 }
330
331 static indic_position_t
332 consonant_position_from_face (const indic_shape_plan_t *indic_plan,
333 const hb_codepoint_t consonant,
334 const hb_codepoint_t virama,
335 hb_face_t *face)
336 {
337 /* For old-spec, the order of glyphs is Consonant,Virama,
338 * whereas for new-spec, it's Virama,Consonant. However,
339 * some broken fonts (like Free Sans) simply copied lookups
340 * from old-spec to new-spec without modification.
341 * And oddly enough, Uniscribe seems to respect those lookups.
342 * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
343 * base at 0. The font however, only has lookups matching
344 * 930,94D in 'blwf', not the expected 94D,930 (with new-spec
345 * table). As such, we simply match both sequences. Seems
346 * to work. */
347 hb_codepoint_t glyphs[3] = {virama, consonant, virama};
348 if (indic_plan->blwf.would_substitute (glyphs , 2, face) ||
349 indic_plan->blwf.would_substitute (glyphs+1, 2, face))
350 return POS_BELOW_C;
351 if (indic_plan->pstf.would_substitute (glyphs , 2, face) ||
352 indic_plan->pstf.would_substitute (glyphs+1, 2, face))
353 return POS_POST_C;
354 if (indic_plan->pref.would_substitute (glyphs , 2, face) ||
355 indic_plan->pref.would_substitute (glyphs+1, 2, face))
356 return POS_POST_C;
357 return POS_BASE_C;
358 }
359
360
361 enum syllable_type_t {
362 consonant_syllable,
363 vowel_syllable,
364 standalone_cluster,
365 symbol_cluster,
366 broken_cluster,
367 non_indic_cluster,
368 };
369
370 #include "hb-ot-shape-complex-indic-machine.hh"
371
372
373 static void
374 setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
375 hb_buffer_t *buffer,
376 hb_font_t *font HB_UNUSED)
377 {
378 HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
379 HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
380
381 /* We cannot setup masks here. We save information about characters
382 * and setup masks later on in a pause-callback. */
383
384 unsigned int count = buffer->len;
385 hb_glyph_info_t *info = buffer->info;
386 for (unsigned int i = 0; i < count; i++)
387 set_indic_properties (info[i]);
388 }
389
390 static void
391 setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
392 hb_font_t *font HB_UNUSED,
393 hb_buffer_t *buffer)
394 {
395 find_syllables (buffer);
396 foreach_syllable (buffer, start, end)
397 buffer->unsafe_to_break (start, end);
398 }
399
400 static int
401 compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
402 {
403 int a = pa->indic_position();
404 int b = pb->indic_position();
405
406 return a < b ? -1 : a == b ? 0 : +1;
407 }
408
409
410
411 static void
412 update_consonant_positions (const hb_ot_shape_plan_t *plan,
413 hb_font_t *font,
414 hb_buffer_t *buffer)
415 {
416 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
417
418 if (indic_plan->config->base_pos != BASE_POS_LAST)
419 return;
420
421 hb_codepoint_t virama;
422 if (indic_plan->get_virama_glyph (font, &virama))
423 {
424 hb_face_t *face = font->face;
425 unsigned int count = buffer->len;
426 hb_glyph_info_t *info = buffer->info;
427 for (unsigned int i = 0; i < count; i++)
428 if (info[i].indic_position() == POS_BASE_C)
429 {
430 hb_codepoint_t consonant = info[i].codepoint;
431 info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
432 }
433 }
434 }
435
436
437 /* Rules from:
438 * https://docs.microsqoft.com/en-us/typography/script-development/devanagari */
439
440 static void
441 initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
442 hb_face_t *face,
443 hb_buffer_t *buffer,
444 unsigned int start, unsigned int end)
445 {
446 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
447 hb_glyph_info_t *info = buffer->info;
448
449 /* https://github.com/harfbuzz/harfbuzz/issues/435#issuecomment-335560167
450 * // For compatibility with legacy usage in Kannada,
451 * // Ra+h+ZWJ must behave like Ra+ZWJ+h...
452 */
453 if (buffer->props.script == HB_SCRIPT_KANNADA &&
454 start + 3 <= end &&
455 is_one_of (info[start ], FLAG (OT_Ra)) &&
456 is_one_of (info[start+1], FLAG (OT_H)) &&
457 is_one_of (info[start+2], FLAG (OT_ZWJ)))
458 {
459 buffer->merge_clusters (start+1, start+3);
460 hb_glyph_info_t tmp = info[start+1];
461 info[start+1] = info[start+2];
462 info[start+2] = tmp;
463 }
464
465 /* 1. Find base consonant:
466 *
467 * The shaping engine finds the base consonant of the syllable, using the
468 * following algorithm: starting from the end of the syllable, move backwards
469 * until a consonant is found that does not have a below-base or post-base
470 * form (post-base forms have to follow below-base forms), or that is not a
471 * pre-base-reordering Ra, or arrive at the first consonant. The consonant
472 * stopped at will be the base.
473 *
474 * o If the syllable starts with Ra + Halant (in a script that has Reph)
475 * and has more than one consonant, Ra is excluded from candidates for
476 * base consonants.
477 */
478
479 unsigned int base = end;
480 bool has_reph = false;
481
482 {
483 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
484 * and has more than one consonant, Ra is excluded from candidates for
485 * base consonants. */
486 unsigned int limit = start;
487 if (indic_plan->mask_array[RPHF] &&
488 start + 3 <= end &&
489 (
490 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
491 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
492 ))
493 {
494 /* See if it matches the 'rphf' feature. */
495 hb_codepoint_t glyphs[3] = {info[start].codepoint,
496 info[start + 1].codepoint,
497 indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
498 info[start + 2].codepoint : 0};
499 if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
500 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
501 indic_plan->rphf.would_substitute (glyphs, 3, face)))
502 {
503 limit += 2;
504 while (limit < end && is_joiner (info[limit]))
505 limit++;
506 base = start;
507 has_reph = true;
508 }
509 } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
510 {
511 limit += 1;
512 while (limit < end && is_joiner (info[limit]))
513 limit++;
514 base = start;
515 has_reph = true;
516 }
517
518 switch (indic_plan->config->base_pos)
519 {
520 case BASE_POS_LAST:
521 {
522 /* -> starting from the end of the syllable, move backwards */
523 unsigned int i = end;
524 bool seen_below = false;
525 do {
526 i--;
527 /* -> until a consonant is found */
528 if (is_consonant (info[i]))
529 {
530 /* -> that does not have a below-base or post-base form
531 * (post-base forms have to follow below-base forms), */
532 if (info[i].indic_position() != POS_BELOW_C &&
533 (info[i].indic_position() != POS_POST_C || seen_below))
534 {
535 base = i;
536 break;
537 }
538 if (info[i].indic_position() == POS_BELOW_C)
539 seen_below = true;
540
541 /* -> or that is not a pre-base-reordering Ra,
542 *
543 * IMPLEMENTATION NOTES:
544 *
545 * Our pre-base-reordering Ra's are marked POS_POST_C, so will be skipped
546 * by the logic above already.
547 */
548
549 /* -> or arrive at the first consonant. The consonant stopped at will
550 * be the base. */
551 base = i;
552 }
553 else
554 {
555 /* A ZWJ after a Halant stops the base search, and requests an explicit
556 * half form.
557 * A ZWJ before a Halant, requests a subjoined form instead, and hence
558 * search continues. This is particularly important for Bengali
559 * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
560 if (start < i &&
561 info[i].indic_category() == OT_ZWJ &&
562 info[i - 1].indic_category() == OT_H)
563 break;
564 }
565 } while (i > limit);
566 }
567 break;
568
569 case BASE_POS_LAST_SINHALA:
570 {
571 /* Sinhala base positioning is slightly different from main Indic, in that:
572 * 1. Its ZWJ behavior is different,
573 * 2. We don't need to look into the font for consonant positions.
574 */
575
576 if (!has_reph)
577 base = limit;
578
579 /* Find the last base consonant that is not blocked by ZWJ. If there is
580 * a ZWJ right before a base consonant, that would request a subjoined form. */
581 for (unsigned int i = limit; i < end; i++)
582 if (is_consonant (info[i]))
583 {
584 if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
585 break;
586 else
587 base = i;
588 }
589
590 /* Mark all subsequent consonants as below. */
591 for (unsigned int i = base + 1; i < end; i++)
592 if (is_consonant (info[i]))
593 info[i].indic_position() = POS_BELOW_C;
594 }
595 break;
596 }
597
598 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
599 * and has more than one consonant, Ra is excluded from candidates for
600 * base consonants.
601 *
602 * Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
603 if (has_reph && base == start && limit - base <= 2) {
604 /* Have no other consonant, so Reph is not formed and Ra becomes base. */
605 has_reph = false;
606 }
607 }
608
609
610 /* 2. Decompose and reorder Matras:
611 *
612 * Each matra and any syllable modifier sign in the syllable are moved to the
613 * appropriate position relative to the consonant(s) in the syllable. The
614 * shaping engine decomposes two- or three-part matras into their constituent
615 * parts before any repositioning. Matra characters are classified by which
616 * consonant in a conjunct they have affinity for and are reordered to the
617 * following positions:
618 *
619 * o Before first half form in the syllable
620 * o After subjoined consonants
621 * o After post-form consonant
622 * o After main consonant (for above marks)
623 *
624 * IMPLEMENTATION NOTES:
625 *
626 * The normalize() routine has already decomposed matras for us, so we don't
627 * need to worry about that.
628 */
629
630
631 /* 3. Reorder marks to canonical order:
632 *
633 * Adjacent nukta and halant or nukta and vedic sign are always repositioned
634 * if necessary, so that the nukta is first.
635 *
636 * IMPLEMENTATION NOTES:
637 *
638 * We don't need to do this: the normalize() routine already did this for us.
639 */
640
641
642 /* Reorder characters */
643
644 for (unsigned int i = start; i < base; i++)
645 info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
646
647 if (base < end)
648 info[base].indic_position() = POS_BASE_C;
649
650 /* Mark final consonants. A final consonant is one appearing after a matra.
651 * Happens in Sinhala. */
652 for (unsigned int i = base + 1; i < end; i++)
653 if (info[i].indic_category() == OT_M) {
654 for (unsigned int j = i + 1; j < end; j++)
655 if (is_consonant (info[j])) {
656 info[j].indic_position() = POS_FINAL_C;
657 break;
658 }
659 break;
660 }
661
662 /* Handle beginning Ra */
663 if (has_reph)
664 info[start].indic_position() = POS_RA_TO_BECOME_REPH;
665
666 /* For old-style Indic script tags, move the first post-base Halant after
667 * last consonant.
668 *
669 * Reports suggest that in some scripts Uniscribe does this only if there
670 * is *not* a Halant after last consonant already (eg. Kannada), while it
671 * does it unconditionally in other scripts (eg. Malayalam, Bengali). We
672 * don't currently know about other scripts, so we whitelist Malayalam and
673 * Bengali for now.
674 *
675 * Kannada test case:
676 * U+0C9A,U+0CCD,U+0C9A,U+0CCD
677 * With some versions of Lohit Kannada.
678 * https://bugs.freedesktop.org/show_bug.cgi?id=59118
679 *
680 * Malayalam test case:
681 * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
682 * With lohit-ttf-20121122/Lohit-Malayalam.ttf
683 *
684 * Bengali test case
685 * U+0998,U+09CD,U+09AF,U+09CD
686 * With Windows XP vrinda.ttf
687 * https://github.com/harfbuzz/harfbuzz/issues/1073
688 */
689 if (indic_plan->is_old_spec)
690 {
691 bool disallow_double_halants = buffer->props.script != HB_SCRIPT_MALAYALAM &&
692 buffer->props.script != HB_SCRIPT_BENGALI;
693 for (unsigned int i = base + 1; i < end; i++)
694 if (info[i].indic_category() == OT_H)
695 {
696 unsigned int j;
697 for (j = end - 1; j > i; j--)
698 if (is_consonant (info[j]) ||
699 (disallow_double_halants && info[j].indic_category() == OT_H))
700 break;
701 if (info[j].indic_category() != OT_H && j > i) {
702 /* Move Halant to after last consonant. */
703 hb_glyph_info_t t = info[i];
704 memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
705 info[j] = t;
706 }
707 break;
708 }
709 }
710
711 /* Attach misc marks to previous char to move with them. */
712 {
713 indic_position_t last_pos = POS_START;
714 for (unsigned int i = start; i < end; i++)
715 {
716 if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | FLAG (OT_H))))
717 {
718 info[i].indic_position() = last_pos;
719 if (unlikely (info[i].indic_category() == OT_H &&
720 info[i].indic_position() == POS_PRE_M))
721 {
722 /*
723 * Uniscribe doesn't move the Halant with Left Matra.
724 * TEST: U+092B,U+093F,U+094DE
725 * We follow. This is important for the Sinhala
726 * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
727 * where U+0DD9 is a left matra and U+0DCA is the virama.
728 * We don't want to move the virama with the left matra.
729 * TEST: U+0D9A,U+0DDA
730 */
731 for (unsigned int j = i; j > start; j--)
732 if (info[j - 1].indic_position() != POS_PRE_M) {
733 info[i].indic_position() = info[j - 1].indic_position();
734 break;
735 }
736 }
737 } else if (info[i].indic_position() != POS_SMVD) {
738 last_pos = (indic_position_t) info[i].indic_position();
739 }
740 }
741 }
742 /* For post-base consonants let them own anything before them
743 * since the last consonant or matra. */
744 {
745 unsigned int last = base;
746 for (unsigned int i = base + 1; i < end; i++)
747 if (is_consonant (info[i]))
748 {
749 for (unsigned int j = last + 1; j < i; j++)
750 if (info[j].indic_position() < POS_SMVD)
751 info[j].indic_position() = info[i].indic_position();
752 last = i;
753 } else if (info[i].indic_category() == OT_M)
754 last = i;
755 }
756
757
758 {
759 /* Use syllable() for sort accounting temporarily. */
760 unsigned int syllable = info[start].syllable();
761 for (unsigned int i = start; i < end; i++)
762 info[i].syllable() = i - start;
763
764 /* Sit tight, rock 'n roll! */
765 hb_stable_sort (info + start, end - start, compare_indic_order);
766 /* Find base again */
767 base = end;
768 for (unsigned int i = start; i < end; i++)
769 if (info[i].indic_position() == POS_BASE_C)
770 {
771 base = i;
772 break;
773 }
774 /* Things are out-of-control for post base positions, they may shuffle
775 * around like crazy. In old-spec mode, we move halants around, so in
776 * that case merge all clusters after base. Otherwise, check the sort
777 * order and merge as needed.
778 * For pre-base stuff, we handle cluster issues in final reordering.
779 *
780 * We could use buffer->sort() for this, if there was no special
781 * reordering of pre-base stuff happening later...
782 */
783 if (indic_plan->is_old_spec || end - base > 127)
784 buffer->merge_clusters (base, end);
785 else
786 {
787 /* Note! syllable() is a one-byte field. */
788 for (unsigned int i = base; i < end; i++)
789 if (info[i].syllable() != 255)
790 {
791 unsigned int max = i;
792 unsigned int j = start + info[i].syllable();
793 while (j != i)
794 {
795 max = MAX (max, j);
796 unsigned int next = start + info[j].syllable();
797 info[j].syllable() = 255; /* So we don't process j later again. */
798 j = next;
799 }
800 if (i != max)
801 buffer->merge_clusters (i, max + 1);
802 }
803 }
804
805 /* Put syllable back in. */
806 for (unsigned int i = start; i < end; i++)
807 info[i].syllable() = syllable;
808 }
809
810 /* Setup masks now */
811
812 {
813 hb_mask_t mask;
814
815 /* Reph */
816 for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
817 info[i].mask |= indic_plan->mask_array[RPHF];
818
819 /* Pre-base */
820 mask = indic_plan->mask_array[HALF];
821 if (!indic_plan->is_old_spec &&
822 indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
823 mask |= indic_plan->mask_array[BLWF];
824 for (unsigned int i = start; i < base; i++)
825 info[i].mask |= mask;
826 /* Base */
827 mask = 0;
828 if (base < end)
829 info[base].mask |= mask;
830 /* Post-base */
831 mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
832 for (unsigned int i = base + 1; i < end; i++)
833 info[i].mask |= mask;
834 }
835
836 if (indic_plan->is_old_spec &&
837 buffer->props.script == HB_SCRIPT_DEVANAGARI)
838 {
839 /* Old-spec eye-lash Ra needs special handling. From the
840 * spec:
841 *
842 * "The feature 'below-base form' is applied to consonants
843 * having below-base forms and following the base consonant.
844 * The exception is vattu, which may appear below half forms
845 * as well as below the base glyph. The feature 'below-base
846 * form' will be applied to all such occurrences of Ra as well."
847 *
848 * Test case: U+0924,U+094D,U+0930,U+094d,U+0915
849 * with Sanskrit 2003 font.
850 *
851 * However, note that Ra,Halant,ZWJ is the correct way to
852 * request eyelash form of Ra, so we wouldbn't inhibit it
853 * in that sequence.
854 *
855 * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
856 */
857 for (unsigned int i = start; i + 1 < base; i++)
858 if (info[i ].indic_category() == OT_Ra &&
859 info[i+1].indic_category() == OT_H &&
860 (i + 2 == base ||
861 info[i+2].indic_category() != OT_ZWJ))
862 {
863 info[i ].mask |= indic_plan->mask_array[BLWF];
864 info[i+1].mask |= indic_plan->mask_array[BLWF];
865 }
866 }
867
868 unsigned int pref_len = 2;
869 if (indic_plan->mask_array[PREF] && base + pref_len < end)
870 {
871 /* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */
872 for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
873 hb_codepoint_t glyphs[2];
874 for (unsigned int j = 0; j < pref_len; j++)
875 glyphs[j] = info[i + j].codepoint;
876 if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
877 {
878 for (unsigned int j = 0; j < pref_len; j++)
879 info[i++].mask |= indic_plan->mask_array[PREF];
880 break;
881 }
882 }
883 }
884
885 /* Apply ZWJ/ZWNJ effects */
886 for (unsigned int i = start + 1; i < end; i++)
887 if (is_joiner (info[i])) {
888 bool non_joiner = info[i].indic_category() == OT_ZWNJ;
889 unsigned int j = i;
890
891 do {
892 j--;
893
894 /* ZWJ/ZWNJ should disable CJCT. They do that by simply
895 * being there, since we don't skip them for the CJCT
896 * feature (ie. F_MANUAL_ZWJ) */
897
898 /* A ZWNJ disables HALF. */
899 if (non_joiner)
900 info[j].mask &= ~indic_plan->mask_array[HALF];
901
902 } while (j > start && !is_consonant (info[j]));
903 }
904 }
905
906 static void
907 initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
908 hb_face_t *face,
909 hb_buffer_t *buffer,
910 unsigned int start, unsigned int end)
911 {
912 /* We treat placeholder/dotted-circle as if they are consonants, so we
913 * should just chain. Only if not in compatibility mode that is... */
914
915 if (hb_options ().uniscribe_bug_compatible)
916 {
917 /* For dotted-circle, this is what Uniscribe does:
918 * If dotted-circle is the last glyph, it just does nothing.
919 * Ie. It doesn't form Reph. */
920 if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
921 return;
922 }
923
924 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
925 }
926
927 static void
928 initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
929 hb_face_t *face,
930 hb_buffer_t *buffer,
931 unsigned int start, unsigned int end)
932 {
933 syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
934 switch (syllable_type)
935 {
936 case vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */
937 case consonant_syllable:
938 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
939 break;
940
941 case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
942 case standalone_cluster:
943 initial_reordering_standalone_cluster (plan, face, buffer, start, end);
944 break;
945
946 case symbol_cluster:
947 case non_indic_cluster:
948 break;
949 }
950 }
951
952 static inline void
953 insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
954 hb_font_t *font,
955 hb_buffer_t *buffer)
956 {
957 /* Note: This loop is extra overhead, but should not be measurable. */
958 bool has_broken_syllables = false;
959 unsigned int count = buffer->len;
960 hb_glyph_info_t *info = buffer->info;
961 for (unsigned int i = 0; i < count; i++)
962 if ((info[i].syllable() & 0x0F) == broken_cluster)
963 {
964 has_broken_syllables = true;
965 break;
966 }
967 if (likely (!has_broken_syllables))
968 return;
969
970
971 hb_codepoint_t dottedcircle_glyph;
972 if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
973 return;
974
975 hb_glyph_info_t dottedcircle = {0};
976 dottedcircle.codepoint = 0x25CCu;
977 set_indic_properties (dottedcircle);
978 dottedcircle.codepoint = dottedcircle_glyph;
979
980 buffer->clear_output ();
981
982 buffer->idx = 0;
983 unsigned int last_syllable = 0;
984 while (buffer->idx < buffer->len && buffer->successful)
985 {
986 unsigned int syllable = buffer->cur().syllable();
987 syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
988 if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
989 {
990 last_syllable = syllable;
991
992 hb_glyph_info_t ginfo = dottedcircle;
993 ginfo.cluster = buffer->cur().cluster;
994 ginfo.mask = buffer->cur().mask;
995 ginfo.syllable() = buffer->cur().syllable();
996 /* TODO Set glyph_props? */
997
998 /* Insert dottedcircle after possible Repha. */
999 while (buffer->idx < buffer->len && buffer->successful &&
1000 last_syllable == buffer->cur().syllable() &&
1001 buffer->cur().indic_category() == OT_Repha)
1002 buffer->next_glyph ();
1003
1004 buffer->output_info (ginfo);
1005 }
1006 else
1007 buffer->next_glyph ();
1008 }
1009
1010 buffer->swap_buffers ();
1011 }
1012
1013 static void
1014 initial_reordering (const hb_ot_shape_plan_t *plan,
1015 hb_font_t *font,
1016 hb_buffer_t *buffer)
1017 {
1018 update_consonant_positions (plan, font, buffer);
1019 insert_dotted_circles (plan, font, buffer);
1020
1021 foreach_syllable (buffer, start, end)
1022 initial_reordering_syllable (plan, font->face, buffer, start, end);
1023 }
1024
1025 static void
1026 final_reordering_syllable (const hb_ot_shape_plan_t *plan,
1027 hb_buffer_t *buffer,
1028 unsigned int start, unsigned int end)
1029 {
1030 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
1031 hb_glyph_info_t *info = buffer->info;
1032
1033
1034 /* This function relies heavily on halant glyphs. Lots of ligation
1035 * and possibly multiple substitutions happened prior to this
1036 * phase, and that might have messed up our properties. Recover
1037 * from a particular case of that where we're fairly sure that a
1038 * class of OT_H is desired but has been lost. */
1039 if (indic_plan->virama_glyph)
1040 {
1041 unsigned int virama_glyph = indic_plan->virama_glyph;
1042 for (unsigned int i = start; i < end; i++)
1043 if (info[i].codepoint == virama_glyph &&
1044 _hb_glyph_info_ligated (&info[i]) &&
1045 _hb_glyph_info_multiplied (&info[i]))
1046 {
1047 /* This will make sure that this glyph passes is_halant() test. */
1048 info[i].indic_category() = OT_H;
1049 _hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
1050 }
1051 }
1052
1053
1054 /* 4. Final reordering:
1055 *
1056 * After the localized forms and basic shaping forms GSUB features have been
1057 * applied (see below), the shaping engine performs some final glyph
1058 * reordering before applying all the remaining font features to the entire
1059 * syllable.
1060 */
1061
1062 bool try_pref = !!indic_plan->mask_array[PREF];
1063
1064 /* Find base again */
1065 unsigned int base;
1066 for (base = start; base < end; base++)
1067 if (info[base].indic_position() >= POS_BASE_C)
1068 {
1069 if (try_pref && base + 1 < end)
1070 {
1071 for (unsigned int i = base + 1; i < end; i++)
1072 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1073 {
1074 if (!(_hb_glyph_info_substituted (&info[i]) &&
1075 _hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
1076 {
1077 /* Ok, this was a 'pref' candidate but didn't form any.
1078 * Base is around here... */
1079 base = i;
1080 while (base < end && is_halant (info[base]))
1081 base++;
1082 info[base].indic_position() = POS_BASE_C;
1083
1084 try_pref = false;
1085 }
1086 break;
1087 }
1088 }
1089 /* For Malayalam, skip over unformed below- (but NOT post-) forms. */
1090 if (buffer->props.script == HB_SCRIPT_MALAYALAM)
1091 {
1092 for (unsigned int i = base + 1; i < end; i++)
1093 {
1094 while (i < end && is_joiner (info[i]))
1095 i++;
1096 if (i == end || !is_halant (info[i]))
1097 break;
1098 i++; /* Skip halant. */
1099 while (i < end && is_joiner (info[i]))
1100 i++;
1101 if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
1102 {
1103 base = i;
1104 info[base].indic_position() = POS_BASE_C;
1105 }
1106 }
1107 }
1108
1109 if (start < base && info[base].indic_position() > POS_BASE_C)
1110 base--;
1111 break;
1112 }
1113 if (base == end && start < base &&
1114 is_one_of (info[base - 1], FLAG (OT_ZWJ)))
1115 base--;
1116 if (base < end)
1117 while (start < base &&
1118 is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_H))))
1119 base--;
1120
1121
1122 /* o Reorder matras:
1123 *
1124 * If a pre-base matra character had been reordered before applying basic
1125 * features, the glyph can be moved closer to the main consonant based on
1126 * whether half-forms had been formed. Actual position for the matra is
1127 * defined as “after last standalone halant glyph, after initial matra
1128 * position and before the main consonant”. If ZWJ or ZWNJ follow this
1129 * halant, position is moved after it.
1130 */
1131
1132 if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
1133 {
1134 /* If we lost track of base, alas, position before last thingy. */
1135 unsigned int new_pos = base == end ? base - 2 : base - 1;
1136
1137 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1138 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1139 * We want to position matra after them.
1140 */
1141 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1142 {
1143 while (new_pos > start &&
1144 !(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_H)))))
1145 new_pos--;
1146
1147 /* If we found no Halant we are done.
1148 * Otherwise only proceed if the Halant does
1149 * not belong to the Matra itself! */
1150 if (is_halant (info[new_pos]) &&
1151 info[new_pos].indic_position() != POS_PRE_M)
1152 {
1153 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1154 if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
1155 new_pos++;
1156 }
1157 else
1158 new_pos = start; /* No move. */
1159 }
1160
1161 if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
1162 {
1163 /* Now go see if there's actually any matras... */
1164 for (unsigned int i = new_pos; i > start; i--)
1165 if (info[i - 1].indic_position () == POS_PRE_M)
1166 {
1167 unsigned int old_pos = i - 1;
1168 if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
1169 base--;
1170
1171 hb_glyph_info_t tmp = info[old_pos];
1172 memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
1173 info[new_pos] = tmp;
1174
1175 /* Note: this merge_clusters() is intentionally *after* the reordering.
1176 * Indic matra reordering is special and tricky... */
1177 buffer->merge_clusters (new_pos, MIN (end, base + 1));
1178
1179 new_pos--;
1180 }
1181 } else {
1182 for (unsigned int i = start; i < base; i++)
1183 if (info[i].indic_position () == POS_PRE_M) {
1184 buffer->merge_clusters (i, MIN (end, base + 1));
1185 break;
1186 }
1187 }
1188 }
1189
1190
1191 /* o Reorder reph:
1192 *
1193 * Reph’s original position is always at the beginning of the syllable,
1194 * (i.e. it is not reordered at the character reordering stage). However,
1195 * it will be reordered according to the basic-forms shaping results.
1196 * Possible positions for reph, depending on the script, are; after main,
1197 * before post-base consonant forms, and after post-base consonant forms.
1198 */
1199
1200 /* Two cases:
1201 *
1202 * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
1203 * we should only move it if the sequence ligated to the repha form.
1204 *
1205 * - If repha is encoded separately and in the logical position, we should only
1206 * move it if it did NOT ligate. If it ligated, it's probably the font trying
1207 * to make it work without the reordering.
1208 */
1209 if (start + 1 < end &&
1210 info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
1211 ((info[start].indic_category() == OT_Repha) ^
1212 _hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
1213 {
1214 unsigned int new_reph_pos;
1215 reph_position_t reph_pos = indic_plan->config->reph_pos;
1216
1217 /* 1. If reph should be positioned after post-base consonant forms,
1218 * proceed to step 5.
1219 */
1220 if (reph_pos == REPH_POS_AFTER_POST)
1221 {
1222 goto reph_step_5;
1223 }
1224
1225 /* 2. If the reph repositioning class is not after post-base: target
1226 * position is after the first explicit halant glyph between the
1227 * first post-reph consonant and last main consonant. If ZWJ or ZWNJ
1228 * are following this halant, position is moved after it. If such
1229 * position is found, this is the target position. Otherwise,
1230 * proceed to the next step.
1231 *
1232 * Note: in old-implementation fonts, where classifications were
1233 * fixed in shaping engine, there was no case where reph position
1234 * will be found on this step.
1235 */
1236 {
1237 new_reph_pos = start + 1;
1238 while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
1239 new_reph_pos++;
1240
1241 if (new_reph_pos < base && is_halant (info[new_reph_pos]))
1242 {
1243 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1244 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1245 new_reph_pos++;
1246 goto reph_move;
1247 }
1248 }
1249
1250 /* 3. If reph should be repositioned after the main consonant: find the
1251 * first consonant not ligated with main, or find the first
1252 * consonant that is not a potential pre-base-reordering Ra.
1253 */
1254 if (reph_pos == REPH_POS_AFTER_MAIN)
1255 {
1256 new_reph_pos = base;
1257 while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
1258 new_reph_pos++;
1259 if (new_reph_pos < end)
1260 goto reph_move;
1261 }
1262
1263 /* 4. If reph should be positioned before post-base consonant, find
1264 * first post-base classified consonant not ligated with main. If no
1265 * consonant is found, the target position should be before the
1266 * first matra, syllable modifier sign or vedic sign.
1267 */
1268 /* This is our take on what step 4 is trying to say (and failing, BADLY). */
1269 if (reph_pos == REPH_POS_AFTER_SUB)
1270 {
1271 new_reph_pos = base;
1272 while (new_reph_pos + 1 < end &&
1273 !( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
1274 new_reph_pos++;
1275 if (new_reph_pos < end)
1276 goto reph_move;
1277 }
1278
1279 /* 5. If no consonant is found in steps 3 or 4, move reph to a position
1280 * immediately before the first post-base matra, syllable modifier
1281 * sign or vedic sign that has a reordering class after the intended
1282 * reph position. For example, if the reordering position for reph
1283 * is post-main, it will skip above-base matras that also have a
1284 * post-main position.
1285 */
1286 reph_step_5:
1287 {
1288 /* Copied from step 2. */
1289 new_reph_pos = start + 1;
1290 while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
1291 new_reph_pos++;
1292
1293 if (new_reph_pos < base && is_halant (info[new_reph_pos]))
1294 {
1295 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1296 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1297 new_reph_pos++;
1298 goto reph_move;
1299 }
1300 }
1301
1302 /* 6. Otherwise, reorder reph to the end of the syllable.
1303 */
1304 {
1305 new_reph_pos = end - 1;
1306 while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
1307 new_reph_pos--;
1308
1309 /*
1310 * If the Reph is to be ending up after a Matra,Halant sequence,
1311 * position it before that Halant so it can interact with the Matra.
1312 * However, if it's a plain Consonant,Halant we shouldn't do that.
1313 * Uniscribe doesn't do this.
1314 * TEST: U+0930,U+094D,U+0915,U+094B,U+094D
1315 */
1316 if (!hb_options ().uniscribe_bug_compatible &&
1317 unlikely (is_halant (info[new_reph_pos]))) {
1318 for (unsigned int i = base + 1; i < new_reph_pos; i++)
1319 if (info[i].indic_category() == OT_M) {
1320 /* Ok, got it. */
1321 new_reph_pos--;
1322 }
1323 }
1324 goto reph_move;
1325 }
1326
1327 reph_move:
1328 {
1329 /* Move */
1330 buffer->merge_clusters (start, new_reph_pos + 1);
1331 hb_glyph_info_t reph = info[start];
1332 memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
1333 info[new_reph_pos] = reph;
1334
1335 if (start < base && base <= new_reph_pos)
1336 base--;
1337 }
1338 }
1339
1340
1341 /* o Reorder pre-base-reordering consonants:
1342 *
1343 * If a pre-base-reordering consonant is found, reorder it according to
1344 * the following rules:
1345 */
1346
1347 if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */
1348 {
1349 for (unsigned int i = base + 1; i < end; i++)
1350 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1351 {
1352 /* 1. Only reorder a glyph produced by substitution during application
1353 * of the <pref> feature. (Note that a font may shape a Ra consonant with
1354 * the feature generally but block it in certain contexts.)
1355 */
1356 /* Note: We just check that something got substituted. We don't check that
1357 * the <pref> feature actually did it...
1358 *
1359 * Reorder pref only if it ligated. */
1360 if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
1361 {
1362 /*
1363 * 2. Try to find a target position the same way as for pre-base matra.
1364 * If it is found, reorder pre-base consonant glyph.
1365 *
1366 * 3. If position is not found, reorder immediately before main
1367 * consonant.
1368 */
1369
1370 unsigned int new_pos = base;
1371 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1372 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1373 * We want to position matra after them.
1374 */
1375 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1376 {
1377 while (new_pos > start &&
1378 !(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_H))))
1379 new_pos--;
1380 }
1381
1382 if (new_pos > start && is_halant (info[new_pos - 1]))
1383 {
1384 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1385 if (new_pos < end && is_joiner (info[new_pos]))
1386 new_pos++;
1387 }
1388
1389 {
1390 unsigned int old_pos = i;
1391
1392 buffer->merge_clusters (new_pos, old_pos + 1);
1393 hb_glyph_info_t tmp = info[old_pos];
1394 memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
1395 info[new_pos] = tmp;
1396
1397 if (new_pos <= base && base < old_pos)
1398 base++;
1399 }
1400 }
1401
1402 break;
1403 }
1404 }
1405
1406
1407 /* Apply 'init' to the Left Matra if it's a word start. */
1408 if (info[start].indic_position () == POS_PRE_M)
1409 {
1410 if (!start ||
1411 !(FLAG_UNSAFE (_hb_glyph_info_get_general_category (&info[start - 1])) &
1412 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
1413 info[start].mask |= indic_plan->mask_array[INIT];
1414 else
1415 buffer->unsafe_to_break (start - 1, start + 1);
1416 }
1417
1418
1419 /*
1420 * Finish off the clusters and go home!
1421 */
1422 if (hb_options ().uniscribe_bug_compatible)
1423 {
1424 switch ((hb_tag_t) plan->props.script)
1425 {
1426 case HB_SCRIPT_TAMIL:
1427 case HB_SCRIPT_SINHALA:
1428 break;
1429
1430 default:
1431 /* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala.
1432 * This means, half forms are submerged into the main consonant's cluster.
1433 * This is unnecessary, and makes cursor positioning harder, but that's what
1434 * Uniscribe does. */
1435 buffer->merge_clusters (start, end);
1436 break;
1437 }
1438 }
1439 }
1440
1441
1442 static void
1443 final_reordering (const hb_ot_shape_plan_t *plan,
1444 hb_font_t *font HB_UNUSED,
1445 hb_buffer_t *buffer)
1446 {
1447 unsigned int count = buffer->len;
1448 if (unlikely (!count)) return;
1449
1450 foreach_syllable (buffer, start, end)
1451 final_reordering_syllable (plan, buffer, start, end);
1452
1453 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
1454 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
1455 }
1456
1457
1458 static void
1459 clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
1460 hb_font_t *font HB_UNUSED,
1461 hb_buffer_t *buffer)
1462 {
1463 hb_glyph_info_t *info = buffer->info;
1464 unsigned int count = buffer->len;
1465 for (unsigned int i = 0; i < count; i++)
1466 info[i].syllable() = 0;
1467 }
1468
1469
1470 static bool
1471 decompose_indic (const hb_ot_shape_normalize_context_t *c,
1472 hb_codepoint_t ab,
1473 hb_codepoint_t *a,
1474 hb_codepoint_t *b)
1475 {
1476 switch (ab)
1477 {
1478 /* Don't decompose these. */
1479 case 0x0931u : return false; /* DEVANAGARI LETTER RRA */
1480 // https://github.com/harfbuzz/harfbuzz/issues/779
1481 case 0x09DCu : return false; /* BENGALI LETTER RRA */
1482 case 0x09DDu : return false; /* BENGALI LETTER RHA */
1483 case 0x0B94u : return false; /* TAMIL LETTER AU */
1484
1485
1486 /*
1487 * Decompose split matras that don't have Unicode decompositions.
1488 */
1489
1490 #if 0
1491 /* Gujarati */
1492 /* This one has no decomposition in Unicode, but needs no decomposition either. */
1493 /* case 0x0AC9u : return false; */
1494
1495 /* Oriya */
1496 case 0x0B57u : *a = no decomp, -> RIGHT; return true;
1497 #endif
1498 }
1499
1500 if ((ab == 0x0DDAu || hb_in_range<hb_codepoint_t> (ab, 0x0DDCu, 0x0DDEu)))
1501 {
1502 /*
1503 * Sinhala split matras... Let the fun begin.
1504 *
1505 * These four characters have Unicode decompositions. However, Uniscribe
1506 * decomposes them "Khmer-style", that is, it uses the character itself to
1507 * get the second half. The first half of all four decompositions is always
1508 * U+0DD9.
1509 *
1510 * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are
1511 * broken with Uniscribe. But we need to support them. As such, we only
1512 * do the Uniscribe-style decomposition if the character is transformed into
1513 * its "sec.half" form by the 'pstf' feature. Otherwise, we fall back to
1514 * Unicode decomposition.
1515 *
1516 * Note that we can't unconditionally use Unicode decomposition. That would
1517 * break some other fonts, that are designed to work with Uniscribe, and
1518 * don't have positioning features for the Unicode-style decomposition.
1519 *
1520 * Argh...
1521 *
1522 * The Uniscribe behavior is now documented in the newly published Sinhala
1523 * spec in 2012:
1524 *
1525 * https://docs.microsoft.com/en-us/typography/script-development/sinhala#shaping
1526 */
1527
1528 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data;
1529
1530 hb_codepoint_t glyph;
1531
1532 if (hb_options ().uniscribe_bug_compatible ||
1533 (c->font->get_nominal_glyph (ab, &glyph) &&
1534 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face)))
1535 {
1536 /* Ok, safe to use Uniscribe-style decomposition. */
1537 *a = 0x0DD9u;
1538 *b = ab;
1539 return true;
1540 }
1541 }
1542
1543 return (bool) c->unicode->decompose (ab, a, b);
1544 }
1545
1546 static bool
1547 compose_indic (const hb_ot_shape_normalize_context_t *c,
1548 hb_codepoint_t a,
1549 hb_codepoint_t b,
1550 hb_codepoint_t *ab)
1551 {
1552 /* Avoid recomposing split matras. */
1553 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
1554 return false;
1555
1556 /* Composition-exclusion exceptions that we want to recompose. */
1557 if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; }
1558
1559 return (bool) c->unicode->compose (a, b, ab);
1560 }
1561
1562
1563 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic =
1564 {
1565 collect_features_indic,
1566 override_features_indic,
1567 data_create_indic,
1568 data_destroy_indic,
1569 nullptr, /* preprocess_text */
1570 nullptr, /* postprocess_glyphs */
1571 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
1572 decompose_indic,
1573 compose_indic,
1574 setup_masks_indic,
1575 nullptr, /* disable_otl */
1576 nullptr, /* reorder_marks */
1577 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
1578 false, /* fallback_position */
1579 };