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.hh"
28#include "hb-ot-shape-complex-vowel-constraints.hh"
29#include "hb-ot-layout.hh"
30
31
32/*
33 * Indic shaper.
34 */
35
36
37/*
38 * Indic configurations. Note that we do not want to keep every single script-specific
39 * behavior in these tables necessarily. This should mainly be used for per-script
40 * properties that are cheaper keeping here, than in the code. Ie. if, say, one and
41 * only one script has an exception, that one script can be if'ed directly in the code,
42 * instead of adding a new flag in these structs.
43 */
44
45enum base_position_t {
46 BASE_POS_LAST_SINHALA,
47 BASE_POS_LAST
48};
49enum reph_position_t {
50 REPH_POS_AFTER_MAIN = POS_AFTER_MAIN,
51 REPH_POS_BEFORE_SUB = POS_BEFORE_SUB,
52 REPH_POS_AFTER_SUB = POS_AFTER_SUB,
53 REPH_POS_BEFORE_POST = POS_BEFORE_POST,
54 REPH_POS_AFTER_POST = POS_AFTER_POST
55};
56enum reph_mode_t {
57 REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */
58 REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */
59 REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */
60};
61enum blwf_mode_t {
62 BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
63 BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */
64};
65struct indic_config_t
66{
67 hb_script_t script;
68 bool has_old_spec;
69 hb_codepoint_t virama;
70 base_position_t base_pos;
71 reph_position_t reph_pos;
72 reph_mode_t reph_mode;
73 blwf_mode_t blwf_mode;
74};
75
76static const indic_config_t indic_configs[] =
77{
78 /* Default. Should be first. */
79 {HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
80 {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
81 {HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
82 {HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
83 {HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
84 {HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
85 {HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
86 {HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
87 {HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
88 {HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
89 {HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA,
90 REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
91};
92
93
94
95/*
96 * Indic shaper.
97 */
98
99static const hb_ot_map_feature_t
100indic_features[] =
101{
102 /*
103 * Basic features.
104 * These features are applied in order, one at a time, after initial_reordering.
105 */
106 {HB_TAG('n','u','k','t'), F_GLOBAL_MANUAL_JOINERS},
107 {HB_TAG('a','k','h','n'), F_GLOBAL_MANUAL_JOINERS},
108 {HB_TAG('r','p','h','f'), F_MANUAL_JOINERS},
109 {HB_TAG('r','k','r','f'), F_GLOBAL_MANUAL_JOINERS},
110 {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS},
111 {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS},
112 {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS},
113 {HB_TAG('h','a','l','f'), F_MANUAL_JOINERS},
114 {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS},
115 {HB_TAG('v','a','t','u'), F_GLOBAL_MANUAL_JOINERS},
116 {HB_TAG('c','j','c','t'), F_GLOBAL_MANUAL_JOINERS},
117 /*
118 * Other features.
119 * These features are applied all at once, after final_reordering
120 * but before clearing syllables.
121 * Default Bengali font in Windows for example has intermixed
122 * lookups for init,pres,abvs,blws features.
123 */
124 {HB_TAG('i','n','i','t'), F_MANUAL_JOINERS},
125 {HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS},
126 {HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS},
127 {HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS},
128 {HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS},
129 {HB_TAG('h','a','l','n'), F_GLOBAL_MANUAL_JOINERS},
130 /*
131 * Positioning features.
132 * We don't care about the types.
133 */
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 */
142enum {
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
162 _DIST,
163 _ABVM,
164 _BLWM,
165
166 INDIC_NUM_FEATURES,
167 INDIC_BASIC_FEATURES = INIT, /* Don't forget to update this! */
168};
169
170static void
171setup_syllables (const hb_ot_shape_plan_t *plan,
172 hb_font_t *font,
173 hb_buffer_t *buffer);
174static void
175initial_reordering (const hb_ot_shape_plan_t *plan,
176 hb_font_t *font,
177 hb_buffer_t *buffer);
178static void
179final_reordering (const hb_ot_shape_plan_t *plan,
180 hb_font_t *font,
181 hb_buffer_t *buffer);
182static void
183clear_syllables (const hb_ot_shape_plan_t *plan,
184 hb_font_t *font,
185 hb_buffer_t *buffer);
186
187static void
188collect_features_indic (hb_ot_shape_planner_t *plan)
189{
190 hb_ot_map_builder_t *map = &plan->map;
191
192 /* Do this before any lookups have been applied. */
193 map->add_gsub_pause (setup_syllables);
194
195 map->enable_feature (HB_TAG('l','o','c','l'));
196 /* The Indic specs do not require ccmp, but we apply it here since if
197 * there is a use of it, it's typically at the beginning. */
198 map->enable_feature (HB_TAG('c','c','m','p'));
199
200
201 unsigned int i = 0;
202 map->add_gsub_pause (initial_reordering);
203
204 for (; i < INDIC_BASIC_FEATURES; i++) {
205 map->add_feature (indic_features[i]);
206 map->add_gsub_pause (nullptr);
207 }
208
209 map->add_gsub_pause (final_reordering);
210
211 for (; i < INDIC_NUM_FEATURES; i++)
212 map->add_feature (indic_features[i]);
213
214 map->enable_feature (HB_TAG('c','a','l','t'));
215 map->enable_feature (HB_TAG('c','l','i','g'));
216
217 map->add_gsub_pause (clear_syllables);
218}
219
220static void
221override_features_indic (hb_ot_shape_planner_t *plan)
222{
223 plan->map.disable_feature (HB_TAG('l','i','g','a'));
224}
225
226
227struct would_substitute_feature_t
228{
229 void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
230 {
231 zero_context = zero_context_;
232 map->get_stage_lookups (0/*GSUB*/,
233 map->get_feature_stage (0/*GSUB*/, feature_tag),
234 &lookups, &count);
235 }
236
237 bool would_substitute (const hb_codepoint_t *glyphs,
238 unsigned int glyphs_count,
239 hb_face_t *face) const
240 {
241 for (unsigned int i = 0; i < count; i++)
242 if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
243 return true;
244 return false;
245 }
246
247 private:
248 const hb_ot_map_t::lookup_map_t *lookups;
249 unsigned int count;
250 bool zero_context;
251};
252
253struct indic_shape_plan_t
254{
255 bool load_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
256 {
257 hb_codepoint_t glyph = virama_glyph.get_relaxed ();
258 if (unlikely (glyph == (hb_codepoint_t) -1))
259 {
260 if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
261 glyph = 0;
262 /* Technically speaking, the spec says we should apply 'locl' to virama too.
263 * Maybe one day... */
264
265 /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
266 * during shape planning... Instead, overwrite it here. */
267 virama_glyph.set_relaxed ((int) glyph);
268 }
269
270 *pglyph = glyph;
271 return glyph != 0;
272 }
273
274 const indic_config_t *config;
275
276 bool is_old_spec;
277 bool uniscribe_bug_compatible;
278 mutable hb_atomic_int_t virama_glyph;
279
280 would_substitute_feature_t rphf;
281 would_substitute_feature_t pref;
282 would_substitute_feature_t blwf;
283 would_substitute_feature_t pstf;
284
285 hb_mask_t mask_array[INDIC_NUM_FEATURES];
286};
287
288static void *
289data_create_indic (const hb_ot_shape_plan_t *plan)
290{
291 indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
292 if (unlikely (!indic_plan))
293 return nullptr;
294
295 indic_plan->config = &indic_configs[0];
296 for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
297 if (plan->props.script == indic_configs[i].script) {
298 indic_plan->config = &indic_configs[i];
299 break;
300 }
301
302 indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
303 indic_plan->uniscribe_bug_compatible = hb_options ().uniscribe_bug_compatible;
304 indic_plan->virama_glyph.set_relaxed (-1);
305
306 /* Use zero-context would_substitute() matching for new-spec of the main
307 * Indic scripts, and scripts with one spec only, but not for old-specs.
308 * The new-spec for all dual-spec scripts says zero-context matching happens.
309 *
310 * However, testing with Malayalam shows that old and new spec both allow
311 * context. Testing with Bengali new-spec however shows that it doesn't.
312 * So, the heuristic here is the way it is. It should *only* be changed,
313 * as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE.
314 */
315 bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
316 indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
317 indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
318 indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
319 indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
320
321 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
322 indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
323 0 : plan->map.get_1_mask (indic_features[i].tag);
324
325 return indic_plan;
326}
327
328static void
329data_destroy_indic (void *data)
330{
331 free (data);
332}
333
334static indic_position_t
335consonant_position_from_face (const indic_shape_plan_t *indic_plan,
336 const hb_codepoint_t consonant,
337 const hb_codepoint_t virama,
338 hb_face_t *face)
339{
340 /* For old-spec, the order of glyphs is Consonant,Virama,
341 * whereas for new-spec, it's Virama,Consonant. However,
342 * some broken fonts (like Free Sans) simply copied lookups
343 * from old-spec to new-spec without modification.
344 * And oddly enough, Uniscribe seems to respect those lookups.
345 * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
346 * base at 0. The font however, only has lookups matching
347 * 930,94D in 'blwf', not the expected 94D,930 (with new-spec
348 * table). As such, we simply match both sequences. Seems
349 * to work. */
350 hb_codepoint_t glyphs[3] = {virama, consonant, virama};
351 if (indic_plan->blwf.would_substitute (glyphs , 2, face) ||
352 indic_plan->blwf.would_substitute (glyphs+1, 2, face))
353 return POS_BELOW_C;
354 if (indic_plan->pstf.would_substitute (glyphs , 2, face) ||
355 indic_plan->pstf.would_substitute (glyphs+1, 2, face))
356 return POS_POST_C;
357 if (indic_plan->pref.would_substitute (glyphs , 2, face) ||
358 indic_plan->pref.would_substitute (glyphs+1, 2, face))
359 return POS_POST_C;
360 return POS_BASE_C;
361}
362
363
364enum syllable_type_t {
365 consonant_syllable,
366 vowel_syllable,
367 standalone_cluster,
368 symbol_cluster,
369 broken_cluster,
370 non_indic_cluster,
371};
372
373#include "hb-ot-shape-complex-indic-machine.hh"
374
375
376static void
377setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
378 hb_buffer_t *buffer,
379 hb_font_t *font HB_UNUSED)
380{
381 HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
382 HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
383
384 /* We cannot setup masks here. We save information about characters
385 * and setup masks later on in a pause-callback. */
386
387 unsigned int count = buffer->len;
388 hb_glyph_info_t *info = buffer->info;
389 for (unsigned int i = 0; i < count; i++)
390 set_indic_properties (info[i]);
391}
392
393static void
394setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
395 hb_font_t *font HB_UNUSED,
396 hb_buffer_t *buffer)
397{
398 find_syllables (buffer);
399 foreach_syllable (buffer, start, end)
400 buffer->unsafe_to_break (start, end);
401}
402
403static int
404compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
405{
406 int a = pa->indic_position();
407 int b = pb->indic_position();
408
409 return a < b ? -1 : a == b ? 0 : +1;
410}
411
412
413
414static void
415update_consonant_positions (const hb_ot_shape_plan_t *plan,
416 hb_font_t *font,
417 hb_buffer_t *buffer)
418{
419 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
420
421 if (indic_plan->config->base_pos != BASE_POS_LAST)
422 return;
423
424 hb_codepoint_t virama;
425 if (indic_plan->load_virama_glyph (font, &virama))
426 {
427 hb_face_t *face = font->face;
428 unsigned int count = buffer->len;
429 hb_glyph_info_t *info = buffer->info;
430 for (unsigned int i = 0; i < count; i++)
431 if (info[i].indic_position() == POS_BASE_C)
432 {
433 hb_codepoint_t consonant = info[i].codepoint;
434 info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
435 }
436 }
437}
438
439
440/* Rules from:
441 * https://docs.microsqoft.com/en-us/typography/script-development/devanagari */
442
443static void
444initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
445 hb_face_t *face,
446 hb_buffer_t *buffer,
447 unsigned int start, unsigned int end)
448{
449 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
450 hb_glyph_info_t *info = buffer->info;
451
452 /* https://github.com/harfbuzz/harfbuzz/issues/435#issuecomment-335560167
453 * // For compatibility with legacy usage in Kannada,
454 * // Ra+h+ZWJ must behave like Ra+ZWJ+h...
455 */
456 if (buffer->props.script == HB_SCRIPT_KANNADA &&
457 start + 3 <= end &&
458 is_one_of (info[start ], FLAG (OT_Ra)) &&
459 is_one_of (info[start+1], FLAG (OT_H)) &&
460 is_one_of (info[start+2], FLAG (OT_ZWJ)))
461 {
462 buffer->merge_clusters (start+1, start+3);
463 hb_glyph_info_t tmp = info[start+1];
464 info[start+1] = info[start+2];
465 info[start+2] = tmp;
466 }
467
468 /* 1. Find base consonant:
469 *
470 * The shaping engine finds the base consonant of the syllable, using the
471 * following algorithm: starting from the end of the syllable, move backwards
472 * until a consonant is found that does not have a below-base or post-base
473 * form (post-base forms have to follow below-base forms), or that is not a
474 * pre-base-reordering Ra, or arrive at the first consonant. The consonant
475 * stopped at will be the base.
476 *
477 * o If the syllable starts with Ra + Halant (in a script that has Reph)
478 * and has more than one consonant, Ra is excluded from candidates for
479 * base consonants.
480 */
481
482 unsigned int base = end;
483 bool has_reph = false;
484
485 {
486 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
487 * and has more than one consonant, Ra is excluded from candidates for
488 * base consonants. */
489 unsigned int limit = start;
490 if (indic_plan->mask_array[RPHF] &&
491 start + 3 <= end &&
492 (
493 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
494 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
495 ))
496 {
497 /* See if it matches the 'rphf' feature. */
498 hb_codepoint_t glyphs[3] = {info[start].codepoint,
499 info[start + 1].codepoint,
500 indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
501 info[start + 2].codepoint : 0};
502 if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
503 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
504 indic_plan->rphf.would_substitute (glyphs, 3, face)))
505 {
506 limit += 2;
507 while (limit < end && is_joiner (info[limit]))
508 limit++;
509 base = start;
510 has_reph = true;
511 }
512 } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
513 {
514 limit += 1;
515 while (limit < end && is_joiner (info[limit]))
516 limit++;
517 base = start;
518 has_reph = true;
519 }
520
521 switch (indic_plan->config->base_pos)
522 {
523 case BASE_POS_LAST:
524 {
525 /* -> starting from the end of the syllable, move backwards */
526 unsigned int i = end;
527 bool seen_below = false;
528 do {
529 i--;
530 /* -> until a consonant is found */
531 if (is_consonant (info[i]))
532 {
533 /* -> that does not have a below-base or post-base form
534 * (post-base forms have to follow below-base forms), */
535 if (info[i].indic_position() != POS_BELOW_C &&
536 (info[i].indic_position() != POS_POST_C || seen_below))
537 {
538 base = i;
539 break;
540 }
541 if (info[i].indic_position() == POS_BELOW_C)
542 seen_below = true;
543
544 /* -> or that is not a pre-base-reordering Ra,
545 *
546 * IMPLEMENTATION NOTES:
547 *
548 * Our pre-base-reordering Ra's are marked POS_POST_C, so will be skipped
549 * by the logic above already.
550 */
551
552 /* -> or arrive at the first consonant. The consonant stopped at will
553 * be the base. */
554 base = i;
555 }
556 else
557 {
558 /* A ZWJ after a Halant stops the base search, and requests an explicit
559 * half form.
560 * A ZWJ before a Halant, requests a subjoined form instead, and hence
561 * search continues. This is particularly important for Bengali
562 * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
563 if (start < i &&
564 info[i].indic_category() == OT_ZWJ &&
565 info[i - 1].indic_category() == OT_H)
566 break;
567 }
568 } while (i > limit);
569 }
570 break;
571
572 case BASE_POS_LAST_SINHALA:
573 {
574 /* Sinhala base positioning is slightly different from main Indic, in that:
575 * 1. Its ZWJ behavior is different,
576 * 2. We don't need to look into the font for consonant positions.
577 */
578
579 if (!has_reph)
580 base = limit;
581
582 /* Find the last base consonant that is not blocked by ZWJ. If there is
583 * a ZWJ right before a base consonant, that would request a subjoined form. */
584 for (unsigned int i = limit; i < end; i++)
585 if (is_consonant (info[i]))
586 {
587 if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
588 break;
589 else
590 base = i;
591 }
592
593 /* Mark all subsequent consonants as below. */
594 for (unsigned int i = base + 1; i < end; i++)
595 if (is_consonant (info[i]))
596 info[i].indic_position() = POS_BELOW_C;
597 }
598 break;
599 }
600
601 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
602 * and has more than one consonant, Ra is excluded from candidates for
603 * base consonants.
604 *
605 * Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
606 if (has_reph && base == start && limit - base <= 2) {
607 /* Have no other consonant, so Reph is not formed and Ra becomes base. */
608 has_reph = false;
609 }
610 }
611
612
613 /* 2. Decompose and reorder Matras:
614 *
615 * Each matra and any syllable modifier sign in the syllable are moved to the
616 * appropriate position relative to the consonant(s) in the syllable. The
617 * shaping engine decomposes two- or three-part matras into their constituent
618 * parts before any repositioning. Matra characters are classified by which
619 * consonant in a conjunct they have affinity for and are reordered to the
620 * following positions:
621 *
622 * o Before first half form in the syllable
623 * o After subjoined consonants
624 * o After post-form consonant
625 * o After main consonant (for above marks)
626 *
627 * IMPLEMENTATION NOTES:
628 *
629 * The normalize() routine has already decomposed matras for us, so we don't
630 * need to worry about that.
631 */
632
633
634 /* 3. Reorder marks to canonical order:
635 *
636 * Adjacent nukta and halant or nukta and vedic sign are always repositioned
637 * if necessary, so that the nukta is first.
638 *
639 * IMPLEMENTATION NOTES:
640 *
641 * We don't need to do this: the normalize() routine already did this for us.
642 */
643
644
645 /* Reorder characters */
646
647 for (unsigned int i = start; i < base; i++)
648 info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
649
650 if (base < end)
651 info[base].indic_position() = POS_BASE_C;
652
653 /* Mark final consonants. A final consonant is one appearing after a matra.
654 * Happens in Sinhala. */
655 for (unsigned int i = base + 1; i < end; i++)
656 if (info[i].indic_category() == OT_M) {
657 for (unsigned int j = i + 1; j < end; j++)
658 if (is_consonant (info[j])) {
659 info[j].indic_position() = POS_FINAL_C;
660 break;
661 }
662 break;
663 }
664
665 /* Handle beginning Ra */
666 if (has_reph)
667 info[start].indic_position() = POS_RA_TO_BECOME_REPH;
668
669 /* For old-style Indic script tags, move the first post-base Halant after
670 * last consonant.
671 *
672 * Reports suggest that in some scripts Uniscribe does this only if there
673 * is *not* a Halant after last consonant already. We know that is the
674 * case for Kannada, while it reorders unconditionally in other scripts,
675 * eg. Malayalam, Bengali, and Devanagari. We don't currently know about
676 * other scripts, so we blacklist Kannada.
677 *
678 * Kannada test case:
679 * U+0C9A,U+0CCD,U+0C9A,U+0CCD
680 * With some versions of Lohit Kannada.
681 * https://bugs.freedesktop.org/show_bug.cgi?id=59118
682 *
683 * Malayalam test case:
684 * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
685 * With lohit-ttf-20121122/Lohit-Malayalam.ttf
686 *
687 * Bengali test case:
688 * U+0998,U+09CD,U+09AF,U+09CD
689 * With Windows XP vrinda.ttf
690 * https://github.com/harfbuzz/harfbuzz/issues/1073
691 *
692 * Devanagari test case:
693 * U+091F,U+094D,U+0930,U+094D
694 * With chandas.ttf
695 * https://github.com/harfbuzz/harfbuzz/issues/1071
696 */
697 if (indic_plan->is_old_spec)
698 {
699 bool disallow_double_halants = buffer->props.script == HB_SCRIPT_KANNADA;
700 for (unsigned int i = base + 1; i < end; i++)
701 if (info[i].indic_category() == OT_H)
702 {
703 unsigned int j;
704 for (j = end - 1; j > i; j--)
705 if (is_consonant (info[j]) ||
706 (disallow_double_halants && info[j].indic_category() == OT_H))
707 break;
708 if (info[j].indic_category() != OT_H && j > i) {
709 /* Move Halant to after last consonant. */
710 hb_glyph_info_t t = info[i];
711 memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
712 info[j] = t;
713 }
714 break;
715 }
716 }
717
718 /* Attach misc marks to previous char to move with them. */
719 {
720 indic_position_t last_pos = POS_START;
721 for (unsigned int i = start; i < end; i++)
722 {
723 if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | FLAG (OT_H))))
724 {
725 info[i].indic_position() = last_pos;
726 if (unlikely (info[i].indic_category() == OT_H &&
727 info[i].indic_position() == POS_PRE_M))
728 {
729 /*
730 * Uniscribe doesn't move the Halant with Left Matra.
731 * TEST: U+092B,U+093F,U+094DE
732 * We follow. This is important for the Sinhala
733 * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
734 * where U+0DD9 is a left matra and U+0DCA is the virama.
735 * We don't want to move the virama with the left matra.
736 * TEST: U+0D9A,U+0DDA
737 */
738 for (unsigned int j = i; j > start; j--)
739 if (info[j - 1].indic_position() != POS_PRE_M) {
740 info[i].indic_position() = info[j - 1].indic_position();
741 break;
742 }
743 }
744 } else if (info[i].indic_position() != POS_SMVD) {
745 last_pos = (indic_position_t) info[i].indic_position();
746 }
747 }
748 }
749 /* For post-base consonants let them own anything before them
750 * since the last consonant or matra. */
751 {
752 unsigned int last = base;
753 for (unsigned int i = base + 1; i < end; i++)
754 if (is_consonant (info[i]))
755 {
756 for (unsigned int j = last + 1; j < i; j++)
757 if (info[j].indic_position() < POS_SMVD)
758 info[j].indic_position() = info[i].indic_position();
759 last = i;
760 } else if (info[i].indic_category() == OT_M)
761 last = i;
762 }
763
764
765 {
766 /* Use syllable() for sort accounting temporarily. */
767 unsigned int syllable = info[start].syllable();
768 for (unsigned int i = start; i < end; i++)
769 info[i].syllable() = i - start;
770
771 /* Sit tight, rock 'n roll! */
772 hb_stable_sort (info + start, end - start, compare_indic_order);
773 /* Find base again */
774 base = end;
775 for (unsigned int i = start; i < end; i++)
776 if (info[i].indic_position() == POS_BASE_C)
777 {
778 base = i;
779 break;
780 }
781 /* Things are out-of-control for post base positions, they may shuffle
782 * around like crazy. In old-spec mode, we move halants around, so in
783 * that case merge all clusters after base. Otherwise, check the sort
784 * order and merge as needed.
785 * For pre-base stuff, we handle cluster issues in final reordering.
786 *
787 * We could use buffer->sort() for this, if there was no special
788 * reordering of pre-base stuff happening later...
789 * We don't want to merge_clusters all of that, which buffer->sort()
790 * would.
791 */
792 if (indic_plan->is_old_spec || end - start > 127)
793 buffer->merge_clusters (base, end);
794 else
795 {
796 /* Note! syllable() is a one-byte field. */
797 for (unsigned int i = base; i < end; i++)
798 if (info[i].syllable() != 255)
799 {
800 unsigned int max = i;
801 unsigned int j = start + info[i].syllable();
802 while (j != i)
803 {
804 max = MAX (max, j);
805 unsigned int next = start + info[j].syllable();
806 info[j].syllable() = 255; /* So we don't process j later again. */
807 j = next;
808 }
809 if (i != max)
810 buffer->merge_clusters (i, max + 1);
811 }
812 }
813
814 /* Put syllable back in. */
815 for (unsigned int i = start; i < end; i++)
816 info[i].syllable() = syllable;
817 }
818
819 /* Setup masks now */
820
821 {
822 hb_mask_t mask;
823
824 /* Reph */
825 for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
826 info[i].mask |= indic_plan->mask_array[RPHF];
827
828 /* Pre-base */
829 mask = indic_plan->mask_array[HALF];
830 if (!indic_plan->is_old_spec &&
831 indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
832 mask |= indic_plan->mask_array[BLWF];
833 for (unsigned int i = start; i < base; i++)
834 info[i].mask |= mask;
835 /* Base */
836 mask = 0;
837 if (base < end)
838 info[base].mask |= mask;
839 /* Post-base */
840 mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
841 for (unsigned int i = base + 1; i < end; i++)
842 info[i].mask |= mask;
843 }
844
845 if (indic_plan->is_old_spec &&
846 buffer->props.script == HB_SCRIPT_DEVANAGARI)
847 {
848 /* Old-spec eye-lash Ra needs special handling. From the
849 * spec:
850 *
851 * "The feature 'below-base form' is applied to consonants
852 * having below-base forms and following the base consonant.
853 * The exception is vattu, which may appear below half forms
854 * as well as below the base glyph. The feature 'below-base
855 * form' will be applied to all such occurrences of Ra as well."
856 *
857 * Test case: U+0924,U+094D,U+0930,U+094d,U+0915
858 * with Sanskrit 2003 font.
859 *
860 * However, note that Ra,Halant,ZWJ is the correct way to
861 * request eyelash form of Ra, so we wouldbn't inhibit it
862 * in that sequence.
863 *
864 * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
865 */
866 for (unsigned int i = start; i + 1 < base; i++)
867 if (info[i ].indic_category() == OT_Ra &&
868 info[i+1].indic_category() == OT_H &&
869 (i + 2 == base ||
870 info[i+2].indic_category() != OT_ZWJ))
871 {
872 info[i ].mask |= indic_plan->mask_array[BLWF];
873 info[i+1].mask |= indic_plan->mask_array[BLWF];
874 }
875 }
876
877 unsigned int pref_len = 2;
878 if (indic_plan->mask_array[PREF] && base + pref_len < end)
879 {
880 /* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */
881 for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
882 hb_codepoint_t glyphs[2];
883 for (unsigned int j = 0; j < pref_len; j++)
884 glyphs[j] = info[i + j].codepoint;
885 if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
886 {
887 for (unsigned int j = 0; j < pref_len; j++)
888 info[i++].mask |= indic_plan->mask_array[PREF];
889 break;
890 }
891 }
892 }
893
894 /* Apply ZWJ/ZWNJ effects */
895 for (unsigned int i = start + 1; i < end; i++)
896 if (is_joiner (info[i])) {
897 bool non_joiner = info[i].indic_category() == OT_ZWNJ;
898 unsigned int j = i;
899
900 do {
901 j--;
902
903 /* ZWJ/ZWNJ should disable CJCT. They do that by simply
904 * being there, since we don't skip them for the CJCT
905 * feature (ie. F_MANUAL_ZWJ) */
906
907 /* A ZWNJ disables HALF. */
908 if (non_joiner)
909 info[j].mask &= ~indic_plan->mask_array[HALF];
910
911 } while (j > start && !is_consonant (info[j]));
912 }
913}
914
915static void
916initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
917 hb_face_t *face,
918 hb_buffer_t *buffer,
919 unsigned int start, unsigned int end)
920{
921 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
922
923 /* We treat placeholder/dotted-circle as if they are consonants, so we
924 * should just chain. Only if not in compatibility mode that is... */
925
926 if (indic_plan->uniscribe_bug_compatible)
927 {
928 /* For dotted-circle, this is what Uniscribe does:
929 * If dotted-circle is the last glyph, it just does nothing.
930 * Ie. It doesn't form Reph. */
931 if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
932 return;
933 }
934
935 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
936}
937
938static void
939initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
940 hb_face_t *face,
941 hb_buffer_t *buffer,
942 unsigned int start, unsigned int end)
943{
944 syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
945 switch (syllable_type)
946 {
947 case vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */
948 case consonant_syllable:
949 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
950 break;
951
952 case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
953 case standalone_cluster:
954 initial_reordering_standalone_cluster (plan, face, buffer, start, end);
955 break;
956
957 case symbol_cluster:
958 case non_indic_cluster:
959 break;
960 }
961}
962
963static inline void
964insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
965 hb_font_t *font,
966 hb_buffer_t *buffer)
967{
968 /* Note: This loop is extra overhead, but should not be measurable.
969 * TODO Use a buffer scratch flag to remove the loop. */
970 bool has_broken_syllables = false;
971 unsigned int count = buffer->len;
972 hb_glyph_info_t *info = buffer->info;
973 for (unsigned int i = 0; i < count; i++)
974 if ((info[i].syllable() & 0x0F) == broken_cluster)
975 {
976 has_broken_syllables = true;
977 break;
978 }
979 if (likely (!has_broken_syllables))
980 return;
981
982
983 hb_codepoint_t dottedcircle_glyph;
984 if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
985 return;
986
987 hb_glyph_info_t dottedcircle = {0};
988 dottedcircle.codepoint = 0x25CCu;
989 set_indic_properties (dottedcircle);
990 dottedcircle.codepoint = dottedcircle_glyph;
991
992 buffer->clear_output ();
993
994 buffer->idx = 0;
995 unsigned int last_syllable = 0;
996 while (buffer->idx < buffer->len && buffer->successful)
997 {
998 unsigned int syllable = buffer->cur().syllable();
999 syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
1000 if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
1001 {
1002 last_syllable = syllable;
1003
1004 hb_glyph_info_t ginfo = dottedcircle;
1005 ginfo.cluster = buffer->cur().cluster;
1006 ginfo.mask = buffer->cur().mask;
1007 ginfo.syllable() = buffer->cur().syllable();
1008 /* TODO Set glyph_props? */
1009
1010 /* Insert dottedcircle after possible Repha. */
1011 while (buffer->idx < buffer->len && buffer->successful &&
1012 last_syllable == buffer->cur().syllable() &&
1013 buffer->cur().indic_category() == OT_Repha)
1014 buffer->next_glyph ();
1015
1016 buffer->output_info (ginfo);
1017 }
1018 else
1019 buffer->next_glyph ();
1020 }
1021 buffer->swap_buffers ();
1022}
1023
1024static void
1025initial_reordering (const hb_ot_shape_plan_t *plan,
1026 hb_font_t *font,
1027 hb_buffer_t *buffer)
1028{
1029 update_consonant_positions (plan, font, buffer);
1030 insert_dotted_circles (plan, font, buffer);
1031
1032 foreach_syllable (buffer, start, end)
1033 initial_reordering_syllable (plan, font->face, buffer, start, end);
1034}
1035
1036static void
1037final_reordering_syllable (const hb_ot_shape_plan_t *plan,
1038 hb_buffer_t *buffer,
1039 unsigned int start, unsigned int end)
1040{
1041 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
1042 hb_glyph_info_t *info = buffer->info;
1043
1044
1045 /* This function relies heavily on halant glyphs. Lots of ligation
1046 * and possibly multiple substitutions happened prior to this
1047 * phase, and that might have messed up our properties. Recover
1048 * from a particular case of that where we're fairly sure that a
1049 * class of OT_H is desired but has been lost. */
1050 /* We don't call load_virama_glyph(), since we know it's already
1051 * loaded. */
1052 hb_codepoint_t virama_glyph = indic_plan->virama_glyph.get_relaxed ();
1053 if (virama_glyph)
1054 {
1055 for (unsigned int i = start; i < end; i++)
1056 if (info[i].codepoint == virama_glyph &&
1057 _hb_glyph_info_ligated (&info[i]) &&
1058 _hb_glyph_info_multiplied (&info[i]))
1059 {
1060 /* This will make sure that this glyph passes is_halant() test. */
1061 info[i].indic_category() = OT_H;
1062 _hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
1063 }
1064 }
1065
1066
1067 /* 4. Final reordering:
1068 *
1069 * After the localized forms and basic shaping forms GSUB features have been
1070 * applied (see below), the shaping engine performs some final glyph
1071 * reordering before applying all the remaining font features to the entire
1072 * syllable.
1073 */
1074
1075 bool try_pref = !!indic_plan->mask_array[PREF];
1076
1077 /* Find base again */
1078 unsigned int base;
1079 for (base = start; base < end; base++)
1080 if (info[base].indic_position() >= POS_BASE_C)
1081 {
1082 if (try_pref && base + 1 < end)
1083 {
1084 for (unsigned int i = base + 1; i < end; i++)
1085 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1086 {
1087 if (!(_hb_glyph_info_substituted (&info[i]) &&
1088 _hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
1089 {
1090 /* Ok, this was a 'pref' candidate but didn't form any.
1091 * Base is around here... */
1092 base = i;
1093 while (base < end && is_halant (info[base]))
1094 base++;
1095 info[base].indic_position() = POS_BASE_C;
1096
1097 try_pref = false;
1098 }
1099 break;
1100 }
1101 }
1102 /* For Malayalam, skip over unformed below- (but NOT post-) forms. */
1103 if (buffer->props.script == HB_SCRIPT_MALAYALAM)
1104 {
1105 for (unsigned int i = base + 1; i < end; i++)
1106 {
1107 while (i < end && is_joiner (info[i]))
1108 i++;
1109 if (i == end || !is_halant (info[i]))
1110 break;
1111 i++; /* Skip halant. */
1112 while (i < end && is_joiner (info[i]))
1113 i++;
1114 if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
1115 {
1116 base = i;
1117 info[base].indic_position() = POS_BASE_C;
1118 }
1119 }
1120 }
1121
1122 if (start < base && info[base].indic_position() > POS_BASE_C)
1123 base--;
1124 break;
1125 }
1126 if (base == end && start < base &&
1127 is_one_of (info[base - 1], FLAG (OT_ZWJ)))
1128 base--;
1129 if (base < end)
1130 while (start < base &&
1131 is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_H))))
1132 base--;
1133
1134
1135 /* o Reorder matras:
1136 *
1137 * If a pre-base matra character had been reordered before applying basic
1138 * features, the glyph can be moved closer to the main consonant based on
1139 * whether half-forms had been formed. Actual position for the matra is
1140 * defined as “after last standalone halant glyph, after initial matra
1141 * position and before the main consonant”. If ZWJ or ZWNJ follow this
1142 * halant, position is moved after it.
1143 *
1144 * IMPLEMENTATION NOTES:
1145 *
1146 * It looks like the last sentence is wrong. Testing, with Windows 7 Uniscribe
1147 * and Devanagari shows that the behavior is best described as:
1148 *
1149 * "If ZWJ follows this halant, matra is NOT repositioned after this halant.
1150 * If ZWNJ follows this halant, position is moved after it."
1151 *
1152 * Test case, with Adobe Devanagari or Nirmala UI:
1153 *
1154 * U+091F,U+094D,U+200C,U+092F,U+093F
1155 * (Matra moves to the middle, after ZWNJ.)
1156 *
1157 * U+091F,U+094D,U+200D,U+092F,U+093F
1158 * (Matra does NOT move, stays to the left.)
1159 *
1160 * https://github.com/harfbuzz/harfbuzz/issues/1070
1161 */
1162
1163 if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
1164 {
1165 /* If we lost track of base, alas, position before last thingy. */
1166 unsigned int new_pos = base == end ? base - 2 : base - 1;
1167
1168 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1169 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1170 * We want to position matra after them.
1171 */
1172 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1173 {
1174 search:
1175 while (new_pos > start &&
1176 !(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_H)))))
1177 new_pos--;
1178
1179 /* If we found no Halant we are done.
1180 * Otherwise only proceed if the Halant does
1181 * not belong to the Matra itself! */
1182 if (is_halant (info[new_pos]) &&
1183 info[new_pos].indic_position() != POS_PRE_M)
1184 {
1185#if 0 // See comment above
1186 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1187 if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
1188 new_pos++;
1189#endif
1190 if (new_pos + 1 < end)
1191 {
1192 /* -> If ZWJ follows this halant, matra is NOT repositioned after this halant. */
1193 if (info[new_pos + 1].indic_category() == OT_ZWJ)
1194 {
1195 /* Keep searching. */
1196 if (new_pos > start)
1197 {
1198 new_pos--;
1199 goto search;
1200 }
1201 }
1202 /* -> If ZWNJ follows this halant, position is moved after it. */
1203 if (info[new_pos + 1].indic_category() == OT_ZWNJ)
1204 new_pos++;
1205 }
1206 }
1207 else
1208 new_pos = start; /* No move. */
1209 }
1210
1211 if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
1212 {
1213 /* Now go see if there's actually any matras... */
1214 for (unsigned int i = new_pos; i > start; i--)
1215 if (info[i - 1].indic_position () == POS_PRE_M)
1216 {
1217 unsigned int old_pos = i - 1;
1218 if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
1219 base--;
1220
1221 hb_glyph_info_t tmp = info[old_pos];
1222 memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
1223 info[new_pos] = tmp;
1224
1225 /* Note: this merge_clusters() is intentionally *after* the reordering.
1226 * Indic matra reordering is special and tricky... */
1227 buffer->merge_clusters (new_pos, MIN (end, base + 1));
1228
1229 new_pos--;
1230 }
1231 } else {
1232 for (unsigned int i = start; i < base; i++)
1233 if (info[i].indic_position () == POS_PRE_M) {
1234 buffer->merge_clusters (i, MIN (end, base + 1));
1235 break;
1236 }
1237 }
1238 }
1239
1240
1241 /* o Reorder reph:
1242 *
1243 * Reph’s original position is always at the beginning of the syllable,
1244 * (i.e. it is not reordered at the character reordering stage). However,
1245 * it will be reordered according to the basic-forms shaping results.
1246 * Possible positions for reph, depending on the script, are; after main,
1247 * before post-base consonant forms, and after post-base consonant forms.
1248 */
1249
1250 /* Two cases:
1251 *
1252 * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
1253 * we should only move it if the sequence ligated to the repha form.
1254 *
1255 * - If repha is encoded separately and in the logical position, we should only
1256 * move it if it did NOT ligate. If it ligated, it's probably the font trying
1257 * to make it work without the reordering.
1258 */
1259 if (start + 1 < end &&
1260 info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
1261 ((info[start].indic_category() == OT_Repha) ^
1262 _hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
1263 {
1264 unsigned int new_reph_pos;
1265 reph_position_t reph_pos = indic_plan->config->reph_pos;
1266
1267 /* 1. If reph should be positioned after post-base consonant forms,
1268 * proceed to step 5.
1269 */
1270 if (reph_pos == REPH_POS_AFTER_POST)
1271 {
1272 goto reph_step_5;
1273 }
1274
1275 /* 2. If the reph repositioning class is not after post-base: target
1276 * position is after the first explicit halant glyph between the
1277 * first post-reph consonant and last main consonant. If ZWJ or ZWNJ
1278 * are following this halant, position is moved after it. If such
1279 * position is found, this is the target position. Otherwise,
1280 * proceed to the next step.
1281 *
1282 * Note: in old-implementation fonts, where classifications were
1283 * fixed in shaping engine, there was no case where reph position
1284 * will be found on this step.
1285 */
1286 {
1287 new_reph_pos = start + 1;
1288 while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
1289 new_reph_pos++;
1290
1291 if (new_reph_pos < base && is_halant (info[new_reph_pos]))
1292 {
1293 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1294 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1295 new_reph_pos++;
1296 goto reph_move;
1297 }
1298 }
1299
1300 /* 3. If reph should be repositioned after the main consonant: find the
1301 * first consonant not ligated with main, or find the first
1302 * consonant that is not a potential pre-base-reordering Ra.
1303 */
1304 if (reph_pos == REPH_POS_AFTER_MAIN)
1305 {
1306 new_reph_pos = base;
1307 while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
1308 new_reph_pos++;
1309 if (new_reph_pos < end)
1310 goto reph_move;
1311 }
1312
1313 /* 4. If reph should be positioned before post-base consonant, find
1314 * first post-base classified consonant not ligated with main. If no
1315 * consonant is found, the target position should be before the
1316 * first matra, syllable modifier sign or vedic sign.
1317 */
1318 /* This is our take on what step 4 is trying to say (and failing, BADLY). */
1319 if (reph_pos == REPH_POS_AFTER_SUB)
1320 {
1321 new_reph_pos = base;
1322 while (new_reph_pos + 1 < end &&
1323 !( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
1324 new_reph_pos++;
1325 if (new_reph_pos < end)
1326 goto reph_move;
1327 }
1328
1329 /* 5. If no consonant is found in steps 3 or 4, move reph to a position
1330 * immediately before the first post-base matra, syllable modifier
1331 * sign or vedic sign that has a reordering class after the intended
1332 * reph position. For example, if the reordering position for reph
1333 * is post-main, it will skip above-base matras that also have a
1334 * post-main position.
1335 */
1336 reph_step_5:
1337 {
1338 /* Copied from step 2. */
1339 new_reph_pos = start + 1;
1340 while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
1341 new_reph_pos++;
1342
1343 if (new_reph_pos < base && is_halant (info[new_reph_pos]))
1344 {
1345 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1346 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1347 new_reph_pos++;
1348 goto reph_move;
1349 }
1350 }
1351
1352 /* 6. Otherwise, reorder reph to the end of the syllable.
1353 */
1354 {
1355 new_reph_pos = end - 1;
1356 while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
1357 new_reph_pos--;
1358
1359 /*
1360 * If the Reph is to be ending up after a Matra,Halant sequence,
1361 * position it before that Halant so it can interact with the Matra.
1362 * However, if it's a plain Consonant,Halant we shouldn't do that.
1363 * Uniscribe doesn't do this.
1364 * TEST: U+0930,U+094D,U+0915,U+094B,U+094D
1365 */
1366 if (!indic_plan->uniscribe_bug_compatible &&
1367 unlikely (is_halant (info[new_reph_pos]))) {
1368 for (unsigned int i = base + 1; i < new_reph_pos; i++)
1369 if (info[i].indic_category() == OT_M) {
1370 /* Ok, got it. */
1371 new_reph_pos--;
1372 }
1373 }
1374 goto reph_move;
1375 }
1376
1377 reph_move:
1378 {
1379 /* Move */
1380 buffer->merge_clusters (start, new_reph_pos + 1);
1381 hb_glyph_info_t reph = info[start];
1382 memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
1383 info[new_reph_pos] = reph;
1384
1385 if (start < base && base <= new_reph_pos)
1386 base--;
1387 }
1388 }
1389
1390
1391 /* o Reorder pre-base-reordering consonants:
1392 *
1393 * If a pre-base-reordering consonant is found, reorder it according to
1394 * the following rules:
1395 */
1396
1397 if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */
1398 {
1399 for (unsigned int i = base + 1; i < end; i++)
1400 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1401 {
1402 /* 1. Only reorder a glyph produced by substitution during application
1403 * of the <pref> feature. (Note that a font may shape a Ra consonant with
1404 * the feature generally but block it in certain contexts.)
1405 */
1406 /* Note: We just check that something got substituted. We don't check that
1407 * the <pref> feature actually did it...
1408 *
1409 * Reorder pref only if it ligated. */
1410 if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
1411 {
1412 /*
1413 * 2. Try to find a target position the same way as for pre-base matra.
1414 * If it is found, reorder pre-base consonant glyph.
1415 *
1416 * 3. If position is not found, reorder immediately before main
1417 * consonant.
1418 */
1419
1420 unsigned int new_pos = base;
1421 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1422 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1423 * We want to position matra after them.
1424 */
1425 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1426 {
1427 while (new_pos > start &&
1428 !(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_H))))
1429 new_pos--;
1430 }
1431
1432 if (new_pos > start && is_halant (info[new_pos - 1]))
1433 {
1434 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1435 if (new_pos < end && is_joiner (info[new_pos]))
1436 new_pos++;
1437 }
1438
1439 {
1440 unsigned int old_pos = i;
1441
1442 buffer->merge_clusters (new_pos, old_pos + 1);
1443 hb_glyph_info_t tmp = info[old_pos];
1444 memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
1445 info[new_pos] = tmp;
1446
1447 if (new_pos <= base && base < old_pos)
1448 base++;
1449 }
1450 }
1451
1452 break;
1453 }
1454 }
1455
1456
1457 /* Apply 'init' to the Left Matra if it's a word start. */
1458 if (info[start].indic_position () == POS_PRE_M)
1459 {
1460 if (!start ||
1461 !(FLAG_UNSAFE (_hb_glyph_info_get_general_category (&info[start - 1])) &
1462 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
1463 info[start].mask |= indic_plan->mask_array[INIT];
1464 else
1465 buffer->unsafe_to_break (start - 1, start + 1);
1466 }
1467
1468
1469 /*
1470 * Finish off the clusters and go home!
1471 */
1472 if (indic_plan->uniscribe_bug_compatible)
1473 {
1474 switch ((hb_tag_t) plan->props.script)
1475 {
1476 case HB_SCRIPT_TAMIL:
1477 case HB_SCRIPT_SINHALA:
1478 break;
1479
1480 default:
1481 /* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala.
1482 * This means, half forms are submerged into the main consonant's cluster.
1483 * This is unnecessary, and makes cursor positioning harder, but that's what
1484 * Uniscribe does. */
1485 buffer->merge_clusters (start, end);
1486 break;
1487 }
1488 }
1489}
1490
1491
1492static void
1493final_reordering (const hb_ot_shape_plan_t *plan,
1494 hb_font_t *font HB_UNUSED,
1495 hb_buffer_t *buffer)
1496{
1497 unsigned int count = buffer->len;
1498 if (unlikely (!count)) return;
1499
1500 foreach_syllable (buffer, start, end)
1501 final_reordering_syllable (plan, buffer, start, end);
1502
1503 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
1504 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
1505}
1506
1507
1508static void
1509clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
1510 hb_font_t *font HB_UNUSED,
1511 hb_buffer_t *buffer)
1512{
1513 hb_glyph_info_t *info = buffer->info;
1514 unsigned int count = buffer->len;
1515 for (unsigned int i = 0; i < count; i++)
1516 info[i].syllable() = 0;
1517}
1518
1519
1520static void
1521preprocess_text_indic (const hb_ot_shape_plan_t *plan,
1522 hb_buffer_t *buffer,
1523 hb_font_t *font)
1524{
1525 _hb_preprocess_text_vowel_constraints (plan, buffer, font);
1526}
1527
1528static bool
1529decompose_indic (const hb_ot_shape_normalize_context_t *c,
1530 hb_codepoint_t ab,
1531 hb_codepoint_t *a,
1532 hb_codepoint_t *b)
1533{
1534 switch (ab)
1535 {
1536 /* Don't decompose these. */
1537 case 0x0931u : return false; /* DEVANAGARI LETTER RRA */
1538 // https://github.com/harfbuzz/harfbuzz/issues/779
1539 case 0x09DCu : return false; /* BENGALI LETTER RRA */
1540 case 0x09DDu : return false; /* BENGALI LETTER RHA */
1541 case 0x0B94u : return false; /* TAMIL LETTER AU */
1542
1543
1544 /*
1545 * Decompose split matras that don't have Unicode decompositions.
1546 */
1547
1548#if 0
1549 /* Gujarati */
1550 /* This one has no decomposition in Unicode, but needs no decomposition either. */
1551 /* case 0x0AC9u : return false; */
1552
1553 /* Oriya */
1554 case 0x0B57u : *a = no decomp, -> RIGHT; return true;
1555#endif
1556 }
1557
1558 if ((ab == 0x0DDAu || hb_in_range<hb_codepoint_t> (ab, 0x0DDCu, 0x0DDEu)))
1559 {
1560 /*
1561 * Sinhala split matras... Let the fun begin.
1562 *
1563 * These four characters have Unicode decompositions. However, Uniscribe
1564 * decomposes them "Khmer-style", that is, it uses the character itself to
1565 * get the second half. The first half of all four decompositions is always
1566 * U+0DD9.
1567 *
1568 * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are
1569 * broken with Uniscribe. But we need to support them. As such, we only
1570 * do the Uniscribe-style decomposition if the character is transformed into
1571 * its "sec.half" form by the 'pstf' feature. Otherwise, we fall back to
1572 * Unicode decomposition.
1573 *
1574 * Note that we can't unconditionally use Unicode decomposition. That would
1575 * break some other fonts, that are designed to work with Uniscribe, and
1576 * don't have positioning features for the Unicode-style decomposition.
1577 *
1578 * Argh...
1579 *
1580 * The Uniscribe behavior is now documented in the newly published Sinhala
1581 * spec in 2012:
1582 *
1583 * https://docs.microsoft.com/en-us/typography/script-development/sinhala#shaping
1584 */
1585
1586 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data;
1587
1588 hb_codepoint_t glyph;
1589
1590 if (hb_options ().uniscribe_bug_compatible ||
1591 (c->font->get_nominal_glyph (ab, &glyph) &&
1592 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face)))
1593 {
1594 /* Ok, safe to use Uniscribe-style decomposition. */
1595 *a = 0x0DD9u;
1596 *b = ab;
1597 return true;
1598 }
1599 }
1600
1601 return (bool) c->unicode->decompose (ab, a, b);
1602}
1603
1604static bool
1605compose_indic (const hb_ot_shape_normalize_context_t *c,
1606 hb_codepoint_t a,
1607 hb_codepoint_t b,
1608 hb_codepoint_t *ab)
1609{
1610 /* Avoid recomposing split matras. */
1611 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
1612 return false;
1613
1614 /* Composition-exclusion exceptions that we want to recompose. */
1615 if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; }
1616
1617 return (bool) c->unicode->compose (a, b, ab);
1618}
1619
1620
1621const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic =
1622{
1623 collect_features_indic,
1624 override_features_indic,
1625 data_create_indic,
1626 data_destroy_indic,
1627 preprocess_text_indic,
1628 nullptr, /* postprocess_glyphs */
1629 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
1630 decompose_indic,
1631 compose_indic,
1632 setup_masks_indic,
1633 HB_TAG_NONE, /* gpos_tag */
1634 nullptr, /* reorder_marks */
1635 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
1636 false, /* fallback_position */
1637};
1638