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 /* buffer var allocations */
31 #define indic_category() complex_var_u8_0() /* indic_category_t */
32 #define indic_position() complex_var_u8_1() /* indic_position_t */
33
34
35 /*
36 * Indic shaper.
37 */
38
39
40 #define IN_HALF_BLOCK(u, Base) (((u) & ~0x7Fu) == (Base))
41
42 #define IS_DEVA(u) (IN_HALF_BLOCK (u, 0x0900u))
43 #define IS_BENG(u) (IN_HALF_BLOCK (u, 0x0980u))
44 #define IS_GURU(u) (IN_HALF_BLOCK (u, 0x0A00u))
45 #define IS_GUJR(u) (IN_HALF_BLOCK (u, 0x0A80u))
46 #define IS_ORYA(u) (IN_HALF_BLOCK (u, 0x0B00u))
47 #define IS_TAML(u) (IN_HALF_BLOCK (u, 0x0B80u))
48 #define IS_TELU(u) (IN_HALF_BLOCK (u, 0x0C00u))
49 #define IS_KNDA(u) (IN_HALF_BLOCK (u, 0x0C80u))
50 #define IS_MLYM(u) (IN_HALF_BLOCK (u, 0x0D00u))
51 #define IS_SINH(u) (IN_HALF_BLOCK (u, 0x0D80u))
52 #define IS_KHMR(u) (IN_HALF_BLOCK (u, 0x1780u))
53
54
55 #define MATRA_POS_LEFT(u) POS_PRE_M
56 #define MATRA_POS_RIGHT(u) ( \
57 IS_DEVA(u) ? POS_AFTER_SUB : \
58 IS_BENG(u) ? POS_AFTER_POST : \
59 IS_GURU(u) ? POS_AFTER_POST : \
60 IS_GUJR(u) ? POS_AFTER_POST : \
61 IS_ORYA(u) ? POS_AFTER_POST : \
62 IS_TAML(u) ? POS_AFTER_POST : \
63 IS_TELU(u) ? (u <= 0x0C42u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
64 IS_KNDA(u) ? (u < 0x0CC3u || u > 0xCD6u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
65 IS_MLYM(u) ? POS_AFTER_POST : \
66 IS_SINH(u) ? POS_AFTER_SUB : \
67 IS_KHMR(u) ? POS_AFTER_POST : \
68 /*default*/ POS_AFTER_SUB \
69 )
70 #define MATRA_POS_TOP(u) ( /* BENG and MLYM don't have top matras. */ \
71 IS_DEVA(u) ? POS_AFTER_SUB : \
72 IS_GURU(u) ? POS_AFTER_POST : /* Deviate from spec */ \
73 IS_GUJR(u) ? POS_AFTER_SUB : \
74 IS_ORYA(u) ? POS_AFTER_MAIN : \
75 IS_TAML(u) ? POS_AFTER_SUB : \
76 IS_TELU(u) ? POS_BEFORE_SUB : \
77 IS_KNDA(u) ? POS_BEFORE_SUB : \
78 IS_SINH(u) ? POS_AFTER_SUB : \
79 IS_KHMR(u) ? POS_AFTER_POST : \
80 /*default*/ POS_AFTER_SUB \
81 )
82 #define MATRA_POS_BOTTOM(u) ( \
83 IS_DEVA(u) ? POS_AFTER_SUB : \
84 IS_BENG(u) ? POS_AFTER_SUB : \
85 IS_GURU(u) ? POS_AFTER_POST : \
86 IS_GUJR(u) ? POS_AFTER_POST : \
87 IS_ORYA(u) ? POS_AFTER_SUB : \
88 IS_TAML(u) ? POS_AFTER_POST : \
89 IS_TELU(u) ? POS_BEFORE_SUB : \
90 IS_KNDA(u) ? POS_BEFORE_SUB : \
91 IS_MLYM(u) ? POS_AFTER_POST : \
92 IS_SINH(u) ? POS_AFTER_SUB : \
93 IS_KHMR(u) ? POS_AFTER_POST : \
94 /*default*/ POS_AFTER_SUB \
95 )
96
97 static inline indic_position_t
98 matra_position (hb_codepoint_t u, indic_position_t side)
99 {
100 switch ((int) side)
101 {
102 case POS_PRE_C: return MATRA_POS_LEFT (u);
103 case POS_POST_C: return MATRA_POS_RIGHT (u);
104 case POS_ABOVE_C: return MATRA_POS_TOP (u);
105 case POS_BELOW_C: return MATRA_POS_BOTTOM (u);
106 };
107 return side;
108 }
109
110 /* XXX
111 * This is a hack for now. We should move this data into the main Indic table.
112 * Or completely remove it and just check in the tables.
113 */
114 static const hb_codepoint_t ra_chars[] = {
115 0x0930u, /* Devanagari */
116 0x09B0u, /* Bengali */
117 0x09F0u, /* Bengali */
118 0x0A30u, /* Gurmukhi */ /* No Reph */
119 0x0AB0u, /* Gujarati */
120 0x0B30u, /* Oriya */
121 0x0BB0u, /* Tamil */ /* No Reph */
122 0x0C30u, /* Telugu */ /* Reph formed only with ZWJ */
123 0x0CB0u, /* Kannada */
124 0x0D30u, /* Malayalam */ /* No Reph, Logical Repha */
125
126 0x0DBBu, /* Sinhala */ /* Reph formed only with ZWJ */
127
128 0x179Au, /* Khmer */ /* No Reph, Visual Repha */
129 };
130
131 static inline bool
132 is_ra (hb_codepoint_t u)
133 {
134 for (unsigned int i = 0; i < ARRAY_LENGTH (ra_chars); i++)
135 if (u == ra_chars[i])
136 return true;
137 return false;
138 }
139
140 static inline bool
141 is_one_of (const hb_glyph_info_t &info, unsigned int flags)
142 {
143 /* If it ligated, all bets are off. */
144 if (_hb_glyph_info_ligated (&info)) return false;
145 return !!(FLAG_UNSAFE (info.indic_category()) & flags);
146 }
147
148 static inline bool
149 is_joiner (const hb_glyph_info_t &info)
150 {
151 return is_one_of (info, JOINER_FLAGS);
152 }
153
154 static inline bool
155 is_consonant (const hb_glyph_info_t &info)
156 {
157 return is_one_of (info, CONSONANT_FLAGS);
158 }
159
160 static inline bool
161 is_halant_or_coeng (const hb_glyph_info_t &info)
162 {
163 return is_one_of (info, HALANT_OR_COENG_FLAGS);
164 }
165
166 static inline void
167 set_indic_properties (hb_glyph_info_t &info)
168 {
169 hb_codepoint_t u = info.codepoint;
170 unsigned int type = hb_indic_get_categories (u);
171 indic_category_t cat = (indic_category_t) (type & 0x7Fu);
172 indic_position_t pos = (indic_position_t) (type >> 8);
173
174
175 /*
176 * Re-assign category
177 */
178
179 /* The following act more like the Bindus. */
180 if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x0953u, 0x0954u)))
181 cat = OT_SM;
182 /* The following act like consonants. */
183 else if (unlikely (hb_in_ranges<hb_codepoint_t> (u, 0x0A72u, 0x0A73u,
184 0x1CF5u, 0x1CF6u)))
185 cat = OT_C;
186 /* TODO: The following should only be allowed after a Visarga.
187 * For now, just treat them like regular tone marks. */
188 else if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x1CE2u, 0x1CE8u)))
189 cat = OT_A;
190 /* TODO: The following should only be allowed after some of
191 * the nasalization marks, maybe only for U+1CE9..U+1CF1.
192 * For now, just treat them like tone marks. */
193 else if (unlikely (u == 0x1CEDu))
194 cat = OT_A;
195 /* The following take marks in standalone clusters, similar to Avagraha. */
196 else if (unlikely (hb_in_ranges<hb_codepoint_t> (u, 0xA8F2u, 0xA8F7u,
197 0x1CE9u, 0x1CECu,
198 0x1CEEu, 0x1CF1u)))
199 {
200 cat = OT_Symbol;
201 static_assert (((int) INDIC_SYLLABIC_CATEGORY_AVAGRAHA == OT_Symbol), "");
202 }
203 else if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x17CDu, 0x17D1u) ||
204 u == 0x17CBu || u == 0x17D3u || u == 0x17DDu)) /* Khmer Various signs */
205 {
206 /* These can occur mid-syllable (eg. before matras), even though Unicode marks them as Syllable_Modifier.
207 * https://github.com/roozbehp/unicode-data/issues/5 */
208 cat = OT_M;
209 pos = POS_ABOVE_C;
210 }
211 else if (unlikely (u == 0x0A51u))
212 {
213 /* https://github.com/behdad/harfbuzz/issues/524 */
214 cat = OT_M;
215 pos = POS_BELOW_C;
216 }
217
218 /* According to ScriptExtensions.txt, these Grantha marks may also be used in Tamil,
219 * so the Indic shaper needs to know their categories. */
220 else if (unlikely (u == 0x11301u || u == 0x11303u)) cat = OT_SM;
221 else if (unlikely (u == 0x1133cu)) cat = OT_N;
222
223 else if (unlikely (u == 0x0AFBu)) cat = OT_N; /* https://github.com/behdad/harfbuzz/issues/552 */
224
225 else if (unlikely (u == 0x0980u)) cat = OT_PLACEHOLDER; /* https://github.com/behdad/harfbuzz/issues/538 */
226 else if (unlikely (u == 0x17C6u)) cat = OT_N; /* Khmer Bindu doesn't like to be repositioned. */
227 else if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x2010u, 0x2011u)))
228 cat = OT_PLACEHOLDER;
229 else if (unlikely (u == 0x25CCu)) cat = OT_DOTTEDCIRCLE;
230
231
232 /*
233 * Re-assign position.
234 */
235
236 if ((FLAG_UNSAFE (cat) & CONSONANT_FLAGS))
237 {
238 pos = POS_BASE_C;
239 if (is_ra (u))
240 cat = OT_Ra;
241 }
242 else if (cat == OT_M)
243 {
244 pos = matra_position (u, pos);
245 }
246 else if ((FLAG_UNSAFE (cat) & (FLAG (OT_SM) | FLAG (OT_VD) | FLAG (OT_A) | FLAG (OT_Symbol))))
247 {
248 pos = POS_SMVD;
249 }
250
251 if (unlikely (u == 0x0B01u)) pos = POS_BEFORE_SUB; /* Oriya Bindu is BeforeSub in the spec. */
252
253
254
255 info.indic_category() = cat;
256 info.indic_position() = pos;
257 }
258
259 /*
260 * Things above this line should ideally be moved to the Indic table itself.
261 */
262
263
264 /*
265 * Indic configurations. Note that we do not want to keep every single script-specific
266 * behavior in these tables necessarily. This should mainly be used for per-script
267 * properties that are cheaper keeping here, than in the code. Ie. if, say, one and
268 * only one script has an exception, that one script can be if'ed directly in the code,
269 * instead of adding a new flag in these structs.
270 */
271
272 enum base_position_t {
273 BASE_POS_FIRST,
274 BASE_POS_LAST_SINHALA,
275 BASE_POS_LAST
276 };
277 enum reph_position_t {
278 REPH_POS_AFTER_MAIN = POS_AFTER_MAIN,
279 REPH_POS_BEFORE_SUB = POS_BEFORE_SUB,
280 REPH_POS_AFTER_SUB = POS_AFTER_SUB,
281 REPH_POS_BEFORE_POST = POS_BEFORE_POST,
282 REPH_POS_AFTER_POST = POS_AFTER_POST,
283 REPH_POS_DONT_CARE = POS_RA_TO_BECOME_REPH
284 };
285 enum reph_mode_t {
286 REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */
287 REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */
288 REPH_MODE_VIS_REPHA, /* Encoded Repha character, no reordering needed. */
289 REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */
290 };
291 enum blwf_mode_t {
292 BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
293 BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */
294 };
295 struct indic_config_t
296 {
297 hb_script_t script;
298 bool has_old_spec;
299 hb_codepoint_t virama;
300 base_position_t base_pos;
301 reph_position_t reph_pos;
302 reph_mode_t reph_mode;
303 blwf_mode_t blwf_mode;
304 };
305
306 static const indic_config_t indic_configs[] =
307 {
308 /* Default. Should be first. */
309 {HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
310 {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
311 {HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
312 {HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
313 {HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
314 {HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
315 {HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
316 {HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
317 {HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
318 {HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
319 {HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA,
320 REPH_POS_AFTER_MAIN, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
321 {HB_SCRIPT_KHMER, false,0x17D2u,BASE_POS_FIRST,REPH_POS_DONT_CARE, REPH_MODE_VIS_REPHA,BLWF_MODE_PRE_AND_POST},
322 };
323
324
325
326 /*
327 * Indic shaper.
328 */
329
330 struct feature_list_t {
331 hb_tag_t tag;
332 hb_ot_map_feature_flags_t flags;
333 };
334
335 static const feature_list_t
336 indic_features[] =
337 {
338 /*
339 * Basic features.
340 * These features are applied in order, one at a time, after initial_reordering.
341 */
342 {HB_TAG('n','u','k','t'), F_GLOBAL},
343 {HB_TAG('a','k','h','n'), F_GLOBAL},
344 {HB_TAG('r','p','h','f'), F_NONE},
345 {HB_TAG('r','k','r','f'), F_GLOBAL},
346 {HB_TAG('p','r','e','f'), F_NONE},
347 {HB_TAG('b','l','w','f'), F_NONE},
348 {HB_TAG('a','b','v','f'), F_NONE},
349 {HB_TAG('h','a','l','f'), F_NONE},
350 {HB_TAG('p','s','t','f'), F_NONE},
351 {HB_TAG('v','a','t','u'), F_GLOBAL},
352 {HB_TAG('c','j','c','t'), F_GLOBAL},
353 {HB_TAG('c','f','a','r'), F_NONE},
354 /*
355 * Other features.
356 * These features are applied all at once, after final_reordering.
357 * Default Bengali font in Windows for example has intermixed
358 * lookups for init,pres,abvs,blws features.
359 */
360 {HB_TAG('i','n','i','t'), F_NONE},
361 {HB_TAG('p','r','e','s'), F_GLOBAL},
362 {HB_TAG('a','b','v','s'), F_GLOBAL},
363 {HB_TAG('b','l','w','s'), F_GLOBAL},
364 {HB_TAG('p','s','t','s'), F_GLOBAL},
365 {HB_TAG('h','a','l','n'), F_GLOBAL},
366 /* Positioning features, though we don't care about the types. */
367 {HB_TAG('d','i','s','t'), F_GLOBAL},
368 {HB_TAG('a','b','v','m'), F_GLOBAL},
369 {HB_TAG('b','l','w','m'), F_GLOBAL},
370 };
371
372 /*
373 * Must be in the same order as the indic_features array.
374 */
375 enum {
376 _NUKT,
377 _AKHN,
378 RPHF,
379 _RKRF,
380 PREF,
381 BLWF,
382 ABVF,
383 HALF,
384 PSTF,
385 _VATU,
386 _CJCT,
387 CFAR,
388
389 INIT,
390 _PRES,
391 _ABVS,
392 _BLWS,
393 _PSTS,
394 _HALN,
395 _DIST,
396 _ABVM,
397 _BLWM,
398
399 INDIC_NUM_FEATURES,
400 INDIC_BASIC_FEATURES = INIT /* Don't forget to update this! */
401 };
402
403 static void
404 setup_syllables (const hb_ot_shape_plan_t *plan,
405 hb_font_t *font,
406 hb_buffer_t *buffer);
407 static void
408 initial_reordering (const hb_ot_shape_plan_t *plan,
409 hb_font_t *font,
410 hb_buffer_t *buffer);
411 static void
412 final_reordering (const hb_ot_shape_plan_t *plan,
413 hb_font_t *font,
414 hb_buffer_t *buffer);
415 static void
416 clear_syllables (const hb_ot_shape_plan_t *plan,
417 hb_font_t *font,
418 hb_buffer_t *buffer);
419
420 static void
421 collect_features_indic (hb_ot_shape_planner_t *plan)
422 {
423 hb_ot_map_builder_t *map = &plan->map;
424
425 /* Do this before any lookups have been applied. */
426 map->add_gsub_pause (setup_syllables);
427
428 map->add_global_bool_feature (HB_TAG('l','o','c','l'));
429 /* The Indic specs do not require ccmp, but we apply it here since if
430 * there is a use of it, it's typically at the beginning. */
431 map->add_global_bool_feature (HB_TAG('c','c','m','p'));
432
433
434 unsigned int i = 0;
435 map->add_gsub_pause (initial_reordering);
436 for (; i < INDIC_BASIC_FEATURES; i++) {
437 map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
438 map->add_gsub_pause (nullptr);
439 }
440 map->add_gsub_pause (final_reordering);
441 for (; i < INDIC_NUM_FEATURES; i++) {
442 map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
443 }
444
445 map->add_global_bool_feature (HB_TAG('c','a','l','t'));
446 map->add_global_bool_feature (HB_TAG('c','l','i','g'));
447
448 map->add_gsub_pause (clear_syllables);
449 }
450
451 static void
452 override_features_indic (hb_ot_shape_planner_t *plan)
453 {
454 /* Uniscribe does not apply 'kern' in Khmer. */
455 if (hb_options ().uniscribe_bug_compatible)
456 {
457 switch ((hb_tag_t) plan->props.script)
458 {
459 case HB_SCRIPT_KHMER:
460 plan->map.add_feature (HB_TAG('k','e','r','n'), 0, F_GLOBAL);
461 break;
462 }
463 }
464
465 plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);
466 }
467
468
469 struct would_substitute_feature_t
470 {
471 inline void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
472 {
473 zero_context = zero_context_;
474 map->get_stage_lookups (0/*GSUB*/,
475 map->get_feature_stage (0/*GSUB*/, feature_tag),
476 &lookups, &count);
477 }
478
479 inline bool would_substitute (const hb_codepoint_t *glyphs,
480 unsigned int glyphs_count,
481 hb_face_t *face) const
482 {
483 for (unsigned int i = 0; i < count; i++)
484 if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
485 return true;
486 return false;
487 }
488
489 private:
490 const hb_ot_map_t::lookup_map_t *lookups;
491 unsigned int count;
492 bool zero_context;
493 };
494
495 struct indic_shape_plan_t
496 {
497 ASSERT_POD ();
498
499 inline bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
500 {
501 hb_codepoint_t glyph = virama_glyph;
502 if (unlikely (virama_glyph == (hb_codepoint_t) -1))
503 {
504 if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
505 glyph = 0;
506 /* Technically speaking, the spec says we should apply 'locl' to virama too.
507 * Maybe one day... */
508
509 /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
510 * during shape planning... Instead, overwrite it here. It's safe. Don't worry! */
511 virama_glyph = glyph;
512 }
513
514 *pglyph = glyph;
515 return glyph != 0;
516 }
517
518 const indic_config_t *config;
519
520 bool is_old_spec;
521 mutable hb_codepoint_t virama_glyph;
522
523 would_substitute_feature_t rphf;
524 would_substitute_feature_t pref;
525 would_substitute_feature_t blwf;
526 would_substitute_feature_t pstf;
527
528 hb_mask_t mask_array[INDIC_NUM_FEATURES];
529 };
530
531 static void *
532 data_create_indic (const hb_ot_shape_plan_t *plan)
533 {
534 indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
535 if (unlikely (!indic_plan))
536 return nullptr;
537
538 indic_plan->config = &indic_configs[0];
539 for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
540 if (plan->props.script == indic_configs[i].script) {
541 indic_plan->config = &indic_configs[i];
542 break;
543 }
544
545 indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
546 indic_plan->virama_glyph = (hb_codepoint_t) -1;
547
548 /* Use zero-context would_substitute() matching for new-spec of the main
549 * Indic scripts, and scripts with one spec only, but not for old-specs.
550 * The new-spec for all dual-spec scripts says zero-context matching happens.
551 *
552 * However, testing with Malayalam shows that old and new spec both allow
553 * context. Testing with Bengali new-spec however shows that it doesn't.
554 * So, the heuristic here is the way it is. It should *only* be changed,
555 * as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE.
556 */
557 bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
558 indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
559 indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
560 indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
561 indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
562
563 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
564 indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
565 0 : plan->map.get_1_mask (indic_features[i].tag);
566
567 return indic_plan;
568 }
569
570 static void
571 data_destroy_indic (void *data)
572 {
573 free (data);
574 }
575
576 static indic_position_t
577 consonant_position_from_face (const indic_shape_plan_t *indic_plan,
578 const hb_codepoint_t consonant,
579 const hb_codepoint_t virama,
580 hb_face_t *face)
581 {
582 /* For old-spec, the order of glyphs is Consonant,Virama,
583 * whereas for new-spec, it's Virama,Consonant. However,
584 * some broken fonts (like Free Sans) simply copied lookups
585 * from old-spec to new-spec without modification.
586 * And oddly enough, Uniscribe seems to respect those lookups.
587 * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
588 * base at 0. The font however, only has lookups matching
589 * 930,94D in 'blwf', not the expected 94D,930 (with new-spec
590 * table). As such, we simply match both sequences. Seems
591 * to work. */
592 hb_codepoint_t glyphs[3] = {virama, consonant, virama};
593 if (indic_plan->blwf.would_substitute (glyphs , 2, face) ||
594 indic_plan->blwf.would_substitute (glyphs+1, 2, face))
595 return POS_BELOW_C;
596 if (indic_plan->pstf.would_substitute (glyphs , 2, face) ||
597 indic_plan->pstf.would_substitute (glyphs+1, 2, face))
598 return POS_POST_C;
599 if (indic_plan->pref.would_substitute (glyphs , 2, face) ||
600 indic_plan->pref.would_substitute (glyphs+1, 2, face))
601 return POS_POST_C;
602 return POS_BASE_C;
603 }
604
605
606 enum syllable_type_t {
607 consonant_syllable,
608 vowel_syllable,
609 standalone_cluster,
610 symbol_cluster,
611 broken_cluster,
612 non_indic_cluster,
613 };
614
615 #include "hb-ot-shape-complex-indic-machine.hh"
616
617
618 static void
619 setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
620 hb_buffer_t *buffer,
621 hb_font_t *font HB_UNUSED)
622 {
623 HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
624 HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
625
626 /* We cannot setup masks here. We save information about characters
627 * and setup masks later on in a pause-callback. */
628
629 unsigned int count = buffer->len;
630 hb_glyph_info_t *info = buffer->info;
631 for (unsigned int i = 0; i < count; i++)
632 set_indic_properties (info[i]);
633 }
634
635 static void
636 setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
637 hb_font_t *font HB_UNUSED,
638 hb_buffer_t *buffer)
639 {
640 find_syllables (buffer);
641 foreach_syllable (buffer, start, end)
642 buffer->unsafe_to_break (start, end);
643 }
644
645 static int
646 compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
647 {
648 int a = pa->indic_position();
649 int b = pb->indic_position();
650
651 return a < b ? -1 : a == b ? 0 : +1;
652 }
653
654
655
656 static void
657 update_consonant_positions (const hb_ot_shape_plan_t *plan,
658 hb_font_t *font,
659 hb_buffer_t *buffer)
660 {
661 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
662
663 if (indic_plan->config->base_pos != BASE_POS_LAST)
664 return;
665
666 hb_codepoint_t virama;
667 if (indic_plan->get_virama_glyph (font, &virama))
668 {
669 hb_face_t *face = font->face;
670 unsigned int count = buffer->len;
671 hb_glyph_info_t *info = buffer->info;
672 for (unsigned int i = 0; i < count; i++)
673 if (info[i].indic_position() == POS_BASE_C)
674 {
675 hb_codepoint_t consonant = info[i].codepoint;
676 info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
677 }
678 }
679 }
680
681
682 /* Rules from:
683 * https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx */
684
685 static void
686 initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
687 hb_face_t *face,
688 hb_buffer_t *buffer,
689 unsigned int start, unsigned int end)
690 {
691 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
692 hb_glyph_info_t *info = buffer->info;
693
694 /* https://github.com/behdad/harfbuzz/issues/435#issuecomment-335560167
695 * // For compatibility with legacy usage in Kannada,
696 * // Ra+h+ZWJ must behave like Ra+ZWJ+h...
697 */
698 if (buffer->props.script == HB_SCRIPT_KANNADA &&
699 start + 3 <= end &&
700 is_one_of (info[start ], FLAG (OT_Ra)) &&
701 is_one_of (info[start+1], FLAG (OT_H)) &&
702 is_one_of (info[start+2], FLAG (OT_ZWJ)))
703 {
704 buffer->merge_clusters (start+1, start+3);
705 hb_glyph_info_t tmp = info[start+1];
706 info[start+1] = info[start+2];
707 info[start+2] = tmp;
708 }
709
710 /* 1. Find base consonant:
711 *
712 * The shaping engine finds the base consonant of the syllable, using the
713 * following algorithm: starting from the end of the syllable, move backwards
714 * until a consonant is found that does not have a below-base or post-base
715 * form (post-base forms have to follow below-base forms), or that is not a
716 * pre-base reordering Ra, or arrive at the first consonant. The consonant
717 * stopped at will be the base.
718 *
719 * o If the syllable starts with Ra + Halant (in a script that has Reph)
720 * and has more than one consonant, Ra is excluded from candidates for
721 * base consonants.
722 */
723
724 unsigned int base = end;
725 bool has_reph = false;
726
727 {
728 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
729 * and has more than one consonant, Ra is excluded from candidates for
730 * base consonants. */
731 unsigned int limit = start;
732 if (indic_plan->config->reph_pos != REPH_POS_DONT_CARE &&
733 indic_plan->mask_array[RPHF] &&
734 start + 3 <= end &&
735 (
736 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
737 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
738 ))
739 {
740 /* See if it matches the 'rphf' feature. */
741 hb_codepoint_t glyphs[3] = {info[start].codepoint,
742 info[start + 1].codepoint,
743 indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
744 info[start + 2].codepoint : 0};
745 if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
746 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
747 indic_plan->rphf.would_substitute (glyphs, 3, face)))
748 {
749 limit += 2;
750 while (limit < end && is_joiner (info[limit]))
751 limit++;
752 base = start;
753 has_reph = true;
754 }
755 } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
756 {
757 limit += 1;
758 while (limit < end && is_joiner (info[limit]))
759 limit++;
760 base = start;
761 has_reph = true;
762 }
763
764 switch (indic_plan->config->base_pos)
765 {
766 case BASE_POS_LAST:
767 {
768 /* -> starting from the end of the syllable, move backwards */
769 unsigned int i = end;
770 bool seen_below = false;
771 do {
772 i--;
773 /* -> until a consonant is found */
774 if (is_consonant (info[i]))
775 {
776 /* -> that does not have a below-base or post-base form
777 * (post-base forms have to follow below-base forms), */
778 if (info[i].indic_position() != POS_BELOW_C &&
779 (info[i].indic_position() != POS_POST_C || seen_below))
780 {
781 base = i;
782 break;
783 }
784 if (info[i].indic_position() == POS_BELOW_C)
785 seen_below = true;
786
787 /* -> or that is not a pre-base reordering Ra,
788 *
789 * IMPLEMENTATION NOTES:
790 *
791 * Our pre-base reordering Ra's are marked POS_POST_C, so will be skipped
792 * by the logic above already.
793 */
794
795 /* -> or arrive at the first consonant. The consonant stopped at will
796 * be the base. */
797 base = i;
798 }
799 else
800 {
801 /* A ZWJ after a Halant stops the base search, and requests an explicit
802 * half form.
803 * A ZWJ before a Halant, requests a subjoined form instead, and hence
804 * search continues. This is particularly important for Bengali
805 * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
806 if (start < i &&
807 info[i].indic_category() == OT_ZWJ &&
808 info[i - 1].indic_category() == OT_H)
809 break;
810 }
811 } while (i > limit);
812 }
813 break;
814
815 case BASE_POS_LAST_SINHALA:
816 {
817 /* Sinhala base positioning is slightly different from main Indic, in that:
818 * 1. Its ZWJ behavior is different,
819 * 2. We don't need to look into the font for consonant positions.
820 */
821
822 if (!has_reph)
823 base = limit;
824
825 /* Find the last base consonant that is not blocked by ZWJ. If there is
826 * a ZWJ right before a base consonant, that would request a subjoined form. */
827 for (unsigned int i = limit; i < end; i++)
828 if (is_consonant (info[i]))
829 {
830 if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
831 break;
832 else
833 base = i;
834 }
835
836 /* Mark all subsequent consonants as below. */
837 for (unsigned int i = base + 1; i < end; i++)
838 if (is_consonant (info[i]))
839 info[i].indic_position() = POS_BELOW_C;
840 }
841 break;
842
843 case BASE_POS_FIRST:
844 {
845 /* The first consonant is always the base. */
846
847 assert (indic_plan->config->reph_mode == REPH_MODE_VIS_REPHA);
848 assert (!has_reph);
849
850 base = start;
851
852 /* Mark all subsequent consonants as below. */
853 for (unsigned int i = base + 1; i < end; i++)
854 if (is_consonant (info[i]))
855 info[i].indic_position() = POS_BELOW_C;
856 }
857 break;
858 }
859
860 /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
861 * and has more than one consonant, Ra is excluded from candidates for
862 * base consonants.
863 *
864 * Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
865 if (has_reph && base == start && limit - base <= 2) {
866 /* Have no other consonant, so Reph is not formed and Ra becomes base. */
867 has_reph = false;
868 }
869 }
870
871
872 /* 2. Decompose and reorder Matras:
873 *
874 * Each matra and any syllable modifier sign in the syllable are moved to the
875 * appropriate position relative to the consonant(s) in the syllable. The
876 * shaping engine decomposes two- or three-part matras into their constituent
877 * parts before any repositioning. Matra characters are classified by which
878 * consonant in a conjunct they have affinity for and are reordered to the
879 * following positions:
880 *
881 * o Before first half form in the syllable
882 * o After subjoined consonants
883 * o After post-form consonant
884 * o After main consonant (for above marks)
885 *
886 * IMPLEMENTATION NOTES:
887 *
888 * The normalize() routine has already decomposed matras for us, so we don't
889 * need to worry about that.
890 */
891
892
893 /* 3. Reorder marks to canonical order:
894 *
895 * Adjacent nukta and halant or nukta and vedic sign are always repositioned
896 * if necessary, so that the nukta is first.
897 *
898 * IMPLEMENTATION NOTES:
899 *
900 * We don't need to do this: the normalize() routine already did this for us.
901 */
902
903
904 /* Reorder characters */
905
906 for (unsigned int i = start; i < base; i++)
907 info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
908
909 if (base < end)
910 info[base].indic_position() = POS_BASE_C;
911
912 /* Mark final consonants. A final consonant is one appearing after a matra,
913 * like in Khmer. */
914 for (unsigned int i = base + 1; i < end; i++)
915 if (info[i].indic_category() == OT_M) {
916 for (unsigned int j = i + 1; j < end; j++)
917 if (is_consonant (info[j])) {
918 info[j].indic_position() = POS_FINAL_C;
919 break;
920 }
921 break;
922 }
923
924 /* Handle beginning Ra */
925 if (has_reph)
926 info[start].indic_position() = POS_RA_TO_BECOME_REPH;
927
928 /* For old-style Indic script tags, move the first post-base Halant after
929 * last consonant.
930 *
931 * Reports suggest that in some scripts Uniscribe does this only if there
932 * is *not* a Halant after last consonant already (eg. Kannada), while it
933 * does it unconditionally in other scripts (eg. Malayalam). We don't
934 * currently know about other scripts, so we single out Malayalam for now.
935 *
936 * Kannada test case:
937 * U+0C9A,U+0CCD,U+0C9A,U+0CCD
938 * With some versions of Lohit Kannada.
939 * https://bugs.freedesktop.org/show_bug.cgi?id=59118
940 *
941 * Malayalam test case:
942 * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
943 * With lohit-ttf-20121122/Lohit-Malayalam.ttf
944 */
945 if (indic_plan->is_old_spec)
946 {
947 bool disallow_double_halants = buffer->props.script != HB_SCRIPT_MALAYALAM;
948 for (unsigned int i = base + 1; i < end; i++)
949 if (info[i].indic_category() == OT_H)
950 {
951 unsigned int j;
952 for (j = end - 1; j > i; j--)
953 if (is_consonant (info[j]) ||
954 (disallow_double_halants && info[j].indic_category() == OT_H))
955 break;
956 if (info[j].indic_category() != OT_H && j > i) {
957 /* Move Halant to after last consonant. */
958 hb_glyph_info_t t = info[i];
959 memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
960 info[j] = t;
961 }
962 break;
963 }
964 }
965
966 /* Attach misc marks to previous char to move with them. */
967 {
968 indic_position_t last_pos = POS_START;
969 for (unsigned int i = start; i < end; i++)
970 {
971 if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | HALANT_OR_COENG_FLAGS)))
972 {
973 info[i].indic_position() = last_pos;
974 if (unlikely (info[i].indic_category() == OT_H &&
975 info[i].indic_position() == POS_PRE_M))
976 {
977 /*
978 * Uniscribe doesn't move the Halant with Left Matra.
979 * TEST: U+092B,U+093F,U+094DE
980 * We follow. This is important for the Sinhala
981 * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
982 * where U+0DD9 is a left matra and U+0DCA is the virama.
983 * We don't want to move the virama with the left matra.
984 * TEST: U+0D9A,U+0DDA
985 */
986 for (unsigned int j = i; j > start; j--)
987 if (info[j - 1].indic_position() != POS_PRE_M) {
988 info[i].indic_position() = info[j - 1].indic_position();
989 break;
990 }
991 }
992 } else if (info[i].indic_position() != POS_SMVD) {
993 last_pos = (indic_position_t) info[i].indic_position();
994 }
995 }
996 }
997 /* For post-base consonants let them own anything before them
998 * since the last consonant or matra. */
999 {
1000 unsigned int last = base;
1001 for (unsigned int i = base + 1; i < end; i++)
1002 if (is_consonant (info[i]))
1003 {
1004 for (unsigned int j = last + 1; j < i; j++)
1005 if (info[j].indic_position() < POS_SMVD)
1006 info[j].indic_position() = info[i].indic_position();
1007 last = i;
1008 } else if (info[i].indic_category() == OT_M)
1009 last = i;
1010 }
1011
1012
1013 {
1014 /* Use syllable() for sort accounting temporarily. */
1015 unsigned int syllable = info[start].syllable();
1016 for (unsigned int i = start; i < end; i++)
1017 info[i].syllable() = i - start;
1018
1019 /* Sit tight, rock 'n roll! */
1020 hb_stable_sort (info + start, end - start, compare_indic_order);
1021 /* Find base again */
1022 base = end;
1023 for (unsigned int i = start; i < end; i++)
1024 if (info[i].indic_position() == POS_BASE_C)
1025 {
1026 base = i;
1027 break;
1028 }
1029 /* Things are out-of-control for post base positions, they may shuffle
1030 * around like crazy. In old-spec mode, we move halants around, so in
1031 * that case merge all clusters after base. Otherwise, check the sort
1032 * order and merge as needed.
1033 * For pre-base stuff, we handle cluster issues in final reordering.
1034 *
1035 * We could use buffer->sort() for this, if there was no special
1036 * reordering of pre-base stuff happening later...
1037 */
1038 if (indic_plan->is_old_spec || end - base > 127)
1039 buffer->merge_clusters (base, end);
1040 else
1041 {
1042 /* Note! syllable() is a one-byte field. */
1043 for (unsigned int i = base; i < end; i++)
1044 if (info[i].syllable() != 255)
1045 {
1046 unsigned int max = i;
1047 unsigned int j = start + info[i].syllable();
1048 while (j != i)
1049 {
1050 max = MAX (max, j);
1051 unsigned int next = start + info[j].syllable();
1052 info[j].syllable() = 255; /* So we don't process j later again. */
1053 j = next;
1054 }
1055 if (i != max)
1056 buffer->merge_clusters (i, max + 1);
1057 }
1058 }
1059
1060 /* Put syllable back in. */
1061 for (unsigned int i = start; i < end; i++)
1062 info[i].syllable() = syllable;
1063 }
1064
1065 /* Setup masks now */
1066
1067 {
1068 hb_mask_t mask;
1069
1070 /* Reph */
1071 for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
1072 info[i].mask |= indic_plan->mask_array[RPHF];
1073
1074 /* Pre-base */
1075 mask = indic_plan->mask_array[HALF];
1076 if (!indic_plan->is_old_spec &&
1077 indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
1078 mask |= indic_plan->mask_array[BLWF];
1079 for (unsigned int i = start; i < base; i++)
1080 info[i].mask |= mask;
1081 /* Base */
1082 mask = 0;
1083 if (base < end)
1084 info[base].mask |= mask;
1085 /* Post-base */
1086 mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
1087 for (unsigned int i = base + 1; i < end; i++)
1088 info[i].mask |= mask;
1089 }
1090
1091 if (indic_plan->is_old_spec &&
1092 buffer->props.script == HB_SCRIPT_DEVANAGARI)
1093 {
1094 /* Old-spec eye-lash Ra needs special handling. From the
1095 * spec:
1096 *
1097 * "The feature 'below-base form' is applied to consonants
1098 * having below-base forms and following the base consonant.
1099 * The exception is vattu, which may appear below half forms
1100 * as well as below the base glyph. The feature 'below-base
1101 * form' will be applied to all such occurrences of Ra as well."
1102 *
1103 * Test case: U+0924,U+094D,U+0930,U+094d,U+0915
1104 * with Sanskrit 2003 font.
1105 *
1106 * However, note that Ra,Halant,ZWJ is the correct way to
1107 * request eyelash form of Ra, so we wouldbn't inhibit it
1108 * in that sequence.
1109 *
1110 * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
1111 */
1112 for (unsigned int i = start; i + 1 < base; i++)
1113 if (info[i ].indic_category() == OT_Ra &&
1114 info[i+1].indic_category() == OT_H &&
1115 (i + 2 == base ||
1116 info[i+2].indic_category() != OT_ZWJ))
1117 {
1118 info[i ].mask |= indic_plan->mask_array[BLWF];
1119 info[i+1].mask |= indic_plan->mask_array[BLWF];
1120 }
1121 }
1122
1123 unsigned int pref_len = 2;
1124 if (indic_plan->mask_array[PREF] && base + pref_len < end)
1125 {
1126 /* Find a Halant,Ra sequence and mark it for pre-base reordering processing. */
1127 for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
1128 hb_codepoint_t glyphs[2];
1129 for (unsigned int j = 0; j < pref_len; j++)
1130 glyphs[j] = info[i + j].codepoint;
1131 if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
1132 {
1133 for (unsigned int j = 0; j < pref_len; j++)
1134 info[i++].mask |= indic_plan->mask_array[PREF];
1135
1136 /* Mark the subsequent stuff with 'cfar'. Used in Khmer.
1137 * Read the feature spec.
1138 * This allows distinguishing the following cases with MS Khmer fonts:
1139 * U+1784,U+17D2,U+179A,U+17D2,U+1782
1140 * U+1784,U+17D2,U+1782,U+17D2,U+179A
1141 */
1142 if (indic_plan->mask_array[CFAR])
1143 for (; i < end; i++)
1144 info[i].mask |= indic_plan->mask_array[CFAR];
1145
1146 break;
1147 }
1148 }
1149 }
1150
1151 /* Apply ZWJ/ZWNJ effects */
1152 for (unsigned int i = start + 1; i < end; i++)
1153 if (is_joiner (info[i])) {
1154 bool non_joiner = info[i].indic_category() == OT_ZWNJ;
1155 unsigned int j = i;
1156
1157 do {
1158 j--;
1159
1160 /* ZWJ/ZWNJ should disable CJCT. They do that by simply
1161 * being there, since we don't skip them for the CJCT
1162 * feature (ie. F_MANUAL_ZWJ) */
1163
1164 /* A ZWNJ disables HALF. */
1165 if (non_joiner)
1166 info[j].mask &= ~indic_plan->mask_array[HALF];
1167
1168 } while (j > start && !is_consonant (info[j]));
1169 }
1170 }
1171
1172 static void
1173 initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
1174 hb_face_t *face,
1175 hb_buffer_t *buffer,
1176 unsigned int start, unsigned int end)
1177 {
1178 /* We treat placeholder/dotted-circle as if they are consonants, so we
1179 * should just chain. Only if not in compatibility mode that is... */
1180
1181 if (hb_options ().uniscribe_bug_compatible)
1182 {
1183 /* For dotted-circle, this is what Uniscribe does:
1184 * If dotted-circle is the last glyph, it just does nothing.
1185 * Ie. It doesn't form Reph. */
1186 if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
1187 return;
1188 }
1189
1190 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
1191 }
1192
1193 static void
1194 initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
1195 hb_face_t *face,
1196 hb_buffer_t *buffer,
1197 unsigned int start, unsigned int end)
1198 {
1199 syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
1200 switch (syllable_type)
1201 {
1202 case vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */
1203 case consonant_syllable:
1204 initial_reordering_consonant_syllable (plan, face, buffer, start, end);
1205 break;
1206
1207 case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
1208 case standalone_cluster:
1209 initial_reordering_standalone_cluster (plan, face, buffer, start, end);
1210 break;
1211
1212 case symbol_cluster:
1213 case non_indic_cluster:
1214 break;
1215 }
1216 }
1217
1218 static inline void
1219 insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
1220 hb_font_t *font,
1221 hb_buffer_t *buffer)
1222 {
1223 /* Note: This loop is extra overhead, but should not be measurable. */
1224 bool has_broken_syllables = false;
1225 unsigned int count = buffer->len;
1226 hb_glyph_info_t *info = buffer->info;
1227 for (unsigned int i = 0; i < count; i++)
1228 if ((info[i].syllable() & 0x0F) == broken_cluster)
1229 {
1230 has_broken_syllables = true;
1231 break;
1232 }
1233 if (likely (!has_broken_syllables))
1234 return;
1235
1236
1237 hb_codepoint_t dottedcircle_glyph;
1238 if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
1239 return;
1240
1241 hb_glyph_info_t dottedcircle = {0};
1242 dottedcircle.codepoint = 0x25CCu;
1243 set_indic_properties (dottedcircle);
1244 dottedcircle.codepoint = dottedcircle_glyph;
1245
1246 buffer->clear_output ();
1247
1248 buffer->idx = 0;
1249 unsigned int last_syllable = 0;
1250 while (buffer->idx < buffer->len && !buffer->in_error)
1251 {
1252 unsigned int syllable = buffer->cur().syllable();
1253 syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
1254 if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
1255 {
1256 last_syllable = syllable;
1257
1258 hb_glyph_info_t ginfo = dottedcircle;
1259 ginfo.cluster = buffer->cur().cluster;
1260 ginfo.mask = buffer->cur().mask;
1261 ginfo.syllable() = buffer->cur().syllable();
1262 /* TODO Set glyph_props? */
1263
1264 /* Insert dottedcircle after possible Repha. */
1265 while (buffer->idx < buffer->len && !buffer->in_error &&
1266 last_syllable == buffer->cur().syllable() &&
1267 buffer->cur().indic_category() == OT_Repha)
1268 buffer->next_glyph ();
1269
1270 buffer->output_info (ginfo);
1271 }
1272 else
1273 buffer->next_glyph ();
1274 }
1275
1276 buffer->swap_buffers ();
1277 }
1278
1279 static void
1280 initial_reordering (const hb_ot_shape_plan_t *plan,
1281 hb_font_t *font,
1282 hb_buffer_t *buffer)
1283 {
1284 update_consonant_positions (plan, font, buffer);
1285 insert_dotted_circles (plan, font, buffer);
1286
1287 foreach_syllable (buffer, start, end)
1288 initial_reordering_syllable (plan, font->face, buffer, start, end);
1289 }
1290
1291 static void
1292 final_reordering_syllable (const hb_ot_shape_plan_t *plan,
1293 hb_buffer_t *buffer,
1294 unsigned int start, unsigned int end)
1295 {
1296 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
1297 hb_glyph_info_t *info = buffer->info;
1298
1299
1300 /* This function relies heavily on halant glyphs. Lots of ligation
1301 * and possibly multiple substitutions happened prior to this
1302 * phase, and that might have messed up our properties. Recover
1303 * from a particular case of that where we're fairly sure that a
1304 * class of OT_H is desired but has been lost. */
1305 if (indic_plan->virama_glyph)
1306 {
1307 unsigned int virama_glyph = indic_plan->virama_glyph;
1308 for (unsigned int i = start; i < end; i++)
1309 if (info[i].codepoint == virama_glyph &&
1310 _hb_glyph_info_ligated (&info[i]) &&
1311 _hb_glyph_info_multiplied (&info[i]))
1312 {
1313 /* This will make sure that this glyph passes is_halant_or_coeng() test. */
1314 info[i].indic_category() = OT_H;
1315 _hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
1316 }
1317 }
1318
1319
1320 /* 4. Final reordering:
1321 *
1322 * After the localized forms and basic shaping forms GSUB features have been
1323 * applied (see below), the shaping engine performs some final glyph
1324 * reordering before applying all the remaining font features to the entire
1325 * syllable.
1326 */
1327
1328 bool try_pref = !!indic_plan->mask_array[PREF];
1329
1330 /* Find base again */
1331 unsigned int base;
1332 for (base = start; base < end; base++)
1333 if (info[base].indic_position() >= POS_BASE_C)
1334 {
1335 if (try_pref && base + 1 < end)
1336 {
1337 for (unsigned int i = base + 1; i < end; i++)
1338 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1339 {
1340 if (!(_hb_glyph_info_substituted (&info[i]) &&
1341 _hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
1342 {
1343 /* Ok, this was a 'pref' candidate but didn't form any.
1344 * Base is around here... */
1345 base = i;
1346 while (base < end && is_halant_or_coeng (info[base]))
1347 base++;
1348 info[base].indic_position() = POS_BASE_C;
1349
1350 try_pref = false;
1351 }
1352 break;
1353 }
1354 }
1355 /* For Malayalam, skip over unformed below- (but NOT post-) forms. */
1356 if (buffer->props.script == HB_SCRIPT_MALAYALAM)
1357 {
1358 for (unsigned int i = base + 1; i < end; i++)
1359 {
1360 while (i < end && is_joiner (info[i]))
1361 i++;
1362 if (i == end || !is_halant_or_coeng (info[i]))
1363 break;
1364 i++; /* Skip halant. */
1365 while (i < end && is_joiner (info[i]))
1366 i++;
1367 if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
1368 {
1369 base = i;
1370 info[base].indic_position() = POS_BASE_C;
1371 }
1372 }
1373 }
1374
1375 if (start < base && info[base].indic_position() > POS_BASE_C)
1376 base--;
1377 break;
1378 }
1379 if (base == end && start < base &&
1380 is_one_of (info[base - 1], FLAG (OT_ZWJ)))
1381 base--;
1382 if (base < end)
1383 while (start < base &&
1384 is_one_of (info[base], (FLAG (OT_N) | HALANT_OR_COENG_FLAGS)))
1385 base--;
1386
1387
1388 /* o Reorder matras:
1389 *
1390 * If a pre-base matra character had been reordered before applying basic
1391 * features, the glyph can be moved closer to the main consonant based on
1392 * whether half-forms had been formed. Actual position for the matra is
1393 * defined as “after last standalone halant glyph, after initial matra
1394 * position and before the main consonant”. If ZWJ or ZWNJ follow this
1395 * halant, position is moved after it.
1396 */
1397
1398 if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
1399 {
1400 /* If we lost track of base, alas, position before last thingy. */
1401 unsigned int new_pos = base == end ? base - 2 : base - 1;
1402
1403 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1404 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1405 * We want to position matra after them.
1406 */
1407 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1408 {
1409 while (new_pos > start &&
1410 !(is_one_of (info[new_pos], (FLAG (OT_M) | HALANT_OR_COENG_FLAGS))))
1411 new_pos--;
1412
1413 /* If we found no Halant we are done.
1414 * Otherwise only proceed if the Halant does
1415 * not belong to the Matra itself! */
1416 if (is_halant_or_coeng (info[new_pos]) &&
1417 info[new_pos].indic_position() != POS_PRE_M)
1418 {
1419 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1420 if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
1421 new_pos++;
1422 }
1423 else
1424 new_pos = start; /* No move. */
1425 }
1426
1427 if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
1428 {
1429 /* Now go see if there's actually any matras... */
1430 for (unsigned int i = new_pos; i > start; i--)
1431 if (info[i - 1].indic_position () == POS_PRE_M)
1432 {
1433 unsigned int old_pos = i - 1;
1434 if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
1435 base--;
1436
1437 hb_glyph_info_t tmp = info[old_pos];
1438 memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
1439 info[new_pos] = tmp;
1440
1441 /* Note: this merge_clusters() is intentionally *after* the reordering.
1442 * Indic matra reordering is special and tricky... */
1443 buffer->merge_clusters (new_pos, MIN (end, base + 1));
1444
1445 new_pos--;
1446 }
1447 } else {
1448 for (unsigned int i = start; i < base; i++)
1449 if (info[i].indic_position () == POS_PRE_M) {
1450 buffer->merge_clusters (i, MIN (end, base + 1));
1451 break;
1452 }
1453 }
1454 }
1455
1456
1457 /* o Reorder reph:
1458 *
1459 * Reph’s original position is always at the beginning of the syllable,
1460 * (i.e. it is not reordered at the character reordering stage). However,
1461 * it will be reordered according to the basic-forms shaping results.
1462 * Possible positions for reph, depending on the script, are; after main,
1463 * before post-base consonant forms, and after post-base consonant forms.
1464 */
1465
1466 /* Two cases:
1467 *
1468 * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
1469 * we should only move it if the sequence ligated to the repha form.
1470 *
1471 * - If repha is encoded separately and in the logical position, we should only
1472 * move it if it did NOT ligate. If it ligated, it's probably the font trying
1473 * to make it work without the reordering.
1474 */
1475 if (start + 1 < end &&
1476 info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
1477 ((info[start].indic_category() == OT_Repha) ^
1478 _hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
1479 {
1480 unsigned int new_reph_pos;
1481 reph_position_t reph_pos = indic_plan->config->reph_pos;
1482
1483 assert (reph_pos != REPH_POS_DONT_CARE);
1484
1485 /* 1. If reph should be positioned after post-base consonant forms,
1486 * proceed to step 5.
1487 */
1488 if (reph_pos == REPH_POS_AFTER_POST)
1489 {
1490 goto reph_step_5;
1491 }
1492
1493 /* 2. If the reph repositioning class is not after post-base: target
1494 * position is after the first explicit halant glyph between the
1495 * first post-reph consonant and last main consonant. If ZWJ or ZWNJ
1496 * are following this halant, position is moved after it. If such
1497 * position is found, this is the target position. Otherwise,
1498 * proceed to the next step.
1499 *
1500 * Note: in old-implementation fonts, where classifications were
1501 * fixed in shaping engine, there was no case where reph position
1502 * will be found on this step.
1503 */
1504 {
1505 new_reph_pos = start + 1;
1506 while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
1507 new_reph_pos++;
1508
1509 if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
1510 {
1511 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1512 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1513 new_reph_pos++;
1514 goto reph_move;
1515 }
1516 }
1517
1518 /* 3. If reph should be repositioned after the main consonant: find the
1519 * first consonant not ligated with main, or find the first
1520 * consonant that is not a potential pre-base reordering Ra.
1521 */
1522 if (reph_pos == REPH_POS_AFTER_MAIN)
1523 {
1524 new_reph_pos = base;
1525 while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
1526 new_reph_pos++;
1527 if (new_reph_pos < end)
1528 goto reph_move;
1529 }
1530
1531 /* 4. If reph should be positioned before post-base consonant, find
1532 * first post-base classified consonant not ligated with main. If no
1533 * consonant is found, the target position should be before the
1534 * first matra, syllable modifier sign or vedic sign.
1535 */
1536 /* This is our take on what step 4 is trying to say (and failing, BADLY). */
1537 if (reph_pos == REPH_POS_AFTER_SUB)
1538 {
1539 new_reph_pos = base;
1540 while (new_reph_pos + 1 < end &&
1541 !( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
1542 new_reph_pos++;
1543 if (new_reph_pos < end)
1544 goto reph_move;
1545 }
1546
1547 /* 5. If no consonant is found in steps 3 or 4, move reph to a position
1548 * immediately before the first post-base matra, syllable modifier
1549 * sign or vedic sign that has a reordering class after the intended
1550 * reph position. For example, if the reordering position for reph
1551 * is post-main, it will skip above-base matras that also have a
1552 * post-main position.
1553 */
1554 reph_step_5:
1555 {
1556 /* Copied from step 2. */
1557 new_reph_pos = start + 1;
1558 while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
1559 new_reph_pos++;
1560
1561 if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
1562 {
1563 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1564 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1565 new_reph_pos++;
1566 goto reph_move;
1567 }
1568 }
1569
1570 /* 6. Otherwise, reorder reph to the end of the syllable.
1571 */
1572 {
1573 new_reph_pos = end - 1;
1574 while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
1575 new_reph_pos--;
1576
1577 /*
1578 * If the Reph is to be ending up after a Matra,Halant sequence,
1579 * position it before that Halant so it can interact with the Matra.
1580 * However, if it's a plain Consonant,Halant we shouldn't do that.
1581 * Uniscribe doesn't do this.
1582 * TEST: U+0930,U+094D,U+0915,U+094B,U+094D
1583 */
1584 if (!hb_options ().uniscribe_bug_compatible &&
1585 unlikely (is_halant_or_coeng (info[new_reph_pos]))) {
1586 for (unsigned int i = base + 1; i < new_reph_pos; i++)
1587 if (info[i].indic_category() == OT_M) {
1588 /* Ok, got it. */
1589 new_reph_pos--;
1590 }
1591 }
1592 goto reph_move;
1593 }
1594
1595 reph_move:
1596 {
1597 /* Move */
1598 buffer->merge_clusters (start, new_reph_pos + 1);
1599 hb_glyph_info_t reph = info[start];
1600 memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
1601 info[new_reph_pos] = reph;
1602
1603 if (start < base && base <= new_reph_pos)
1604 base--;
1605 }
1606 }
1607
1608
1609 /* o Reorder pre-base reordering consonants:
1610 *
1611 * If a pre-base reordering consonant is found, reorder it according to
1612 * the following rules:
1613 */
1614
1615 if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base reordering Ra. */
1616 {
1617 for (unsigned int i = base + 1; i < end; i++)
1618 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1619 {
1620 /* 1. Only reorder a glyph produced by substitution during application
1621 * of the <pref> feature. (Note that a font may shape a Ra consonant with
1622 * the feature generally but block it in certain contexts.)
1623 */
1624 /* Note: We just check that something got substituted. We don't check that
1625 * the <pref> feature actually did it...
1626 *
1627 * Reorder pref only if it ligated. */
1628 if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
1629 {
1630 /*
1631 * 2. Try to find a target position the same way as for pre-base matra.
1632 * If it is found, reorder pre-base consonant glyph.
1633 *
1634 * 3. If position is not found, reorder immediately before main
1635 * consonant.
1636 */
1637
1638 unsigned int new_pos = base;
1639 /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1640 * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1641 * We want to position matra after them.
1642 */
1643 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1644 {
1645 while (new_pos > start &&
1646 !(is_one_of (info[new_pos - 1], FLAG(OT_M) | HALANT_OR_COENG_FLAGS)))
1647 new_pos--;
1648
1649 /* In Khmer coeng model, a H,Ra can go *after* matras. If it goes after a
1650 * split matra, it should be reordered to *before* the left part of such matra. */
1651 if (new_pos > start && info[new_pos - 1].indic_category() == OT_M)
1652 {
1653 unsigned int old_pos = i;
1654 for (unsigned int j = base + 1; j < old_pos; j++)
1655 if (info[j].indic_category() == OT_M)
1656 {
1657 new_pos--;
1658 break;
1659 }
1660 }
1661 }
1662
1663 if (new_pos > start && is_halant_or_coeng (info[new_pos - 1]))
1664 {
1665 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1666 if (new_pos < end && is_joiner (info[new_pos]))
1667 new_pos++;
1668 }
1669
1670 {
1671 unsigned int old_pos = i;
1672
1673 buffer->merge_clusters (new_pos, old_pos + 1);
1674 hb_glyph_info_t tmp = info[old_pos];
1675 memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
1676 info[new_pos] = tmp;
1677
1678 if (new_pos <= base && base < old_pos)
1679 base++;
1680 }
1681 }
1682
1683 break;
1684 }
1685 }
1686
1687
1688 /* Apply 'init' to the Left Matra if it's a word start. */
1689 if (info[start].indic_position () == POS_PRE_M)
1690 {
1691 if (!start ||
1692 !(FLAG_UNSAFE (_hb_glyph_info_get_general_category (&info[start - 1])) &
1693 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
1694 info[start].mask |= indic_plan->mask_array[INIT];
1695 else
1696 buffer->unsafe_to_break (start - 1, start + 1);
1697 }
1698
1699
1700 /*
1701 * Finish off the clusters and go home!
1702 */
1703 if (hb_options ().uniscribe_bug_compatible)
1704 {
1705 switch ((hb_tag_t) plan->props.script)
1706 {
1707 case HB_SCRIPT_TAMIL:
1708 case HB_SCRIPT_SINHALA:
1709 break;
1710
1711 default:
1712 /* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala.
1713 * This means, half forms are submerged into the main consonant's cluster.
1714 * This is unnecessary, and makes cursor positioning harder, but that's what
1715 * Uniscribe does. */
1716 buffer->merge_clusters (start, end);
1717 break;
1718 }
1719 }
1720 }
1721
1722
1723 static void
1724 final_reordering (const hb_ot_shape_plan_t *plan,
1725 hb_font_t *font HB_UNUSED,
1726 hb_buffer_t *buffer)
1727 {
1728 unsigned int count = buffer->len;
1729 if (unlikely (!count)) return;
1730
1731 foreach_syllable (buffer, start, end)
1732 final_reordering_syllable (plan, buffer, start, end);
1733
1734 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
1735 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
1736 }
1737
1738
1739 static void
1740 clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
1741 hb_font_t *font HB_UNUSED,
1742 hb_buffer_t *buffer)
1743 {
1744 hb_glyph_info_t *info = buffer->info;
1745 unsigned int count = buffer->len;
1746 for (unsigned int i = 0; i < count; i++)
1747 info[i].syllable() = 0;
1748 }
1749
1750
1751 static bool
1752 decompose_indic (const hb_ot_shape_normalize_context_t *c,
1753 hb_codepoint_t ab,
1754 hb_codepoint_t *a,
1755 hb_codepoint_t *b)
1756 {
1757 switch (ab)
1758 {
1759 /* Don't decompose these. */
1760 case 0x0931u : return false; /* DEVANAGARI LETTER RRA */
1761 case 0x0B94u : return false; /* TAMIL LETTER AU */
1762
1763
1764 /*
1765 * Decompose split matras that don't have Unicode decompositions.
1766 */
1767
1768 /* Khmer */
1769 case 0x17BEu : *a = 0x17C1u; *b= 0x17BEu; return true;
1770 case 0x17BFu : *a = 0x17C1u; *b= 0x17BFu; return true;
1771 case 0x17C0u : *a = 0x17C1u; *b= 0x17C0u; return true;
1772 case 0x17C4u : *a = 0x17C1u; *b= 0x17C4u; return true;
1773 case 0x17C5u : *a = 0x17C1u; *b= 0x17C5u; return true;
1774
1775 #if 0
1776 /* Gujarati */
1777 /* This one has no decomposition in Unicode, but needs no decomposition either. */
1778 /* case 0x0AC9u : return false; */
1779
1780 /* Oriya */
1781 case 0x0B57u : *a = no decomp, -> RIGHT; return true;
1782 #endif
1783 }
1784
1785 if ((ab == 0x0DDAu || hb_in_range<hb_codepoint_t> (ab, 0x0DDCu, 0x0DDEu)))
1786 {
1787 /*
1788 * Sinhala split matras... Let the fun begin.
1789 *
1790 * These four characters have Unicode decompositions. However, Uniscribe
1791 * decomposes them "Khmer-style", that is, it uses the character itself to
1792 * get the second half. The first half of all four decompositions is always
1793 * U+0DD9.
1794 *
1795 * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are
1796 * broken with Uniscribe. But we need to support them. As such, we only
1797 * do the Uniscribe-style decomposition if the character is transformed into
1798 * its "sec.half" form by the 'pstf' feature. Otherwise, we fall back to
1799 * Unicode decomposition.
1800 *
1801 * Note that we can't unconditionally use Unicode decomposition. That would
1802 * break some other fonts, that are designed to work with Uniscribe, and
1803 * don't have positioning features for the Unicode-style decomposition.
1804 *
1805 * Argh...
1806 *
1807 * The Uniscribe behavior is now documented in the newly published Sinhala
1808 * spec in 2012:
1809 *
1810 * http://www.microsoft.com/typography/OpenTypeDev/sinhala/intro.htm#shaping
1811 */
1812
1813 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data;
1814
1815 hb_codepoint_t glyph;
1816
1817 if (hb_options ().uniscribe_bug_compatible ||
1818 (c->font->get_nominal_glyph (ab, &glyph) &&
1819 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face)))
1820 {
1821 /* Ok, safe to use Uniscribe-style decomposition. */
1822 *a = 0x0DD9u;
1823 *b = ab;
1824 return true;
1825 }
1826 }
1827
1828 return (bool) c->unicode->decompose (ab, a, b);
1829 }
1830
1831 static bool
1832 compose_indic (const hb_ot_shape_normalize_context_t *c,
1833 hb_codepoint_t a,
1834 hb_codepoint_t b,
1835 hb_codepoint_t *ab)
1836 {
1837 /* Avoid recomposing split matras. */
1838 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
1839 return false;
1840
1841 /* Composition-exclusion exceptions that we want to recompose. */
1842 if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; }
1843
1844 return (bool) c->unicode->compose (a, b, ab);
1845 }
1846
1847
1848 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic =
1849 {
1850 collect_features_indic,
1851 override_features_indic,
1852 data_create_indic,
1853 data_destroy_indic,
1854 nullptr, /* preprocess_text */
1855 nullptr, /* postprocess_glyphs */
1856 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
1857 decompose_indic,
1858 compose_indic,
1859 setup_masks_indic,
1860 nullptr, /* disable_otl */
1861 nullptr, /* reorder_marks */
1862 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
1863 false, /* fallback_position */
1864 };