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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
matra_position(hb_codepoint_t u,indic_position_t side)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
is_ra(hb_codepoint_t u)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
is_one_of(const hb_glyph_info_t & info,unsigned int flags)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_SAFE (info.indic_category()) & flags);
146 }
147 
148 static inline bool
is_joiner(const hb_glyph_info_t & info)149 is_joiner (const hb_glyph_info_t &info)
150 {
151   return is_one_of (info, JOINER_FLAGS);
152 }
153 
154 static inline bool
is_consonant(const hb_glyph_info_t & info)155 is_consonant (const hb_glyph_info_t &info)
156 {
157   return is_one_of (info, CONSONANT_FLAGS);
158 }
159 
160 static inline bool
is_halant_or_coeng(const hb_glyph_info_t & info)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
set_indic_properties(hb_glyph_info_t & info)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 (u, 0x0953u, 0x0954u)))
181     cat = OT_SM;
182   /* The following act like consonants. */
183   else if (unlikely (hb_in_ranges (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 (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 (u, 0xA8F2u, 0xA8F7u,
197 				      0x1CE9u, 0x1CECu,
198 				      0x1CEEu, 0x1CF1u)))
199   {
200     cat = OT_Symbol;
201     ASSERT_STATIC ((int) INDIC_SYLLABIC_CATEGORY_AVAGRAHA == OT_Symbol);
202   }
203   else if (unlikely (u == 0x17C6u)) cat = OT_N; /* Khmer Bindu doesn't like to be repositioned. */
204   else if (unlikely (hb_in_range (u, 0x2010u, 0x2011u)))
205 				    cat = OT_PLACEHOLDER;
206   else if (unlikely (u == 0x25CCu)) cat = OT_DOTTEDCIRCLE;
207 
208 
209   /*
210    * Re-assign position.
211    */
212 
213   if ((FLAG_SAFE (cat) & CONSONANT_FLAGS))
214   {
215     pos = POS_BASE_C;
216     if (is_ra (u))
217       cat = OT_Ra;
218   }
219   else if (cat == OT_M)
220   {
221     pos = matra_position (u, pos);
222   }
223   else if ((FLAG_SAFE (cat) & (FLAG (OT_SM) | FLAG (OT_VD) | FLAG (OT_A) | FLAG (OT_Symbol))))
224   {
225     pos = POS_SMVD;
226   }
227 
228   if (unlikely (u == 0x0B01u)) pos = POS_BEFORE_SUB; /* Oriya Bindu is BeforeSub in the spec. */
229 
230 
231 
232   info.indic_category() = cat;
233   info.indic_position() = pos;
234 }
235 
236 /*
237  * Things above this line should ideally be moved to the Indic table itself.
238  */
239 
240 
241 /*
242  * Indic configurations.  Note that we do not want to keep every single script-specific
243  * behavior in these tables necessarily.  This should mainly be used for per-script
244  * properties that are cheaper keeping here, than in the code.  Ie. if, say, one and
245  * only one script has an exception, that one script can be if'ed directly in the code,
246  * instead of adding a new flag in these structs.
247  */
248 
249 enum base_position_t {
250   BASE_POS_FIRST,
251   BASE_POS_LAST_SINHALA,
252   BASE_POS_LAST
253 };
254 enum reph_position_t {
255   REPH_POS_AFTER_MAIN  = POS_AFTER_MAIN,
256   REPH_POS_BEFORE_SUB  = POS_BEFORE_SUB,
257   REPH_POS_AFTER_SUB   = POS_AFTER_SUB,
258   REPH_POS_BEFORE_POST = POS_BEFORE_POST,
259   REPH_POS_AFTER_POST  = POS_AFTER_POST,
260   REPH_POS_DONT_CARE   = POS_RA_TO_BECOME_REPH
261 };
262 enum reph_mode_t {
263   REPH_MODE_IMPLICIT,  /* Reph formed out of initial Ra,H sequence. */
264   REPH_MODE_EXPLICIT,  /* Reph formed out of initial Ra,H,ZWJ sequence. */
265   REPH_MODE_VIS_REPHA, /* Encoded Repha character, no reordering needed. */
266   REPH_MODE_LOG_REPHA  /* Encoded Repha character, needs reordering. */
267 };
268 enum blwf_mode_t {
269   BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
270   BLWF_MODE_POST_ONLY     /* Below-forms feature applied to post-base only. */
271 };
272 struct indic_config_t
273 {
274   hb_script_t     script;
275   bool            has_old_spec;
276   hb_codepoint_t  virama;
277   base_position_t base_pos;
278   reph_position_t reph_pos;
279   reph_mode_t     reph_mode;
280   blwf_mode_t     blwf_mode;
281 };
282 
283 static const indic_config_t indic_configs[] =
284 {
285   /* Default.  Should be first. */
286   {HB_SCRIPT_INVALID,	false,      0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
287   {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
288   {HB_SCRIPT_BENGALI,	true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB,  REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
289   {HB_SCRIPT_GURMUKHI,	true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
290   {HB_SCRIPT_GUJARATI,	true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
291   {HB_SCRIPT_ORIYA,	true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
292   {HB_SCRIPT_TAMIL,	true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
293   {HB_SCRIPT_TELUGU,	true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
294   {HB_SCRIPT_KANNADA,	true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
295   {HB_SCRIPT_MALAYALAM,	true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
296   {HB_SCRIPT_SINHALA,	false,0x0DCAu,BASE_POS_LAST_SINHALA,
297 						     REPH_POS_AFTER_MAIN, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
298   {HB_SCRIPT_KHMER,	false,0x17D2u,BASE_POS_FIRST,REPH_POS_DONT_CARE,  REPH_MODE_VIS_REPHA,BLWF_MODE_PRE_AND_POST},
299 };
300 
301 
302 
303 /*
304  * Indic shaper.
305  */
306 
307 struct feature_list_t {
308   hb_tag_t tag;
309   hb_ot_map_feature_flags_t flags;
310 };
311 
312 static const feature_list_t
313 indic_features[] =
314 {
315   /*
316    * Basic features.
317    * These features are applied in order, one at a time, after initial_reordering.
318    */
319   {HB_TAG('n','u','k','t'), F_GLOBAL},
320   {HB_TAG('a','k','h','n'), F_GLOBAL},
321   {HB_TAG('r','p','h','f'), F_NONE},
322   {HB_TAG('r','k','r','f'), F_GLOBAL},
323   {HB_TAG('p','r','e','f'), F_NONE},
324   {HB_TAG('b','l','w','f'), F_NONE},
325   {HB_TAG('a','b','v','f'), F_NONE},
326   {HB_TAG('h','a','l','f'), F_NONE},
327   {HB_TAG('p','s','t','f'), F_NONE},
328   {HB_TAG('v','a','t','u'), F_GLOBAL},
329   {HB_TAG('c','j','c','t'), F_GLOBAL},
330   {HB_TAG('c','f','a','r'), F_NONE},
331   /*
332    * Other features.
333    * These features are applied all at once, after final_reordering.
334    * Default Bengali font in Windows for example has intermixed
335    * lookups for init,pres,abvs,blws features.
336    */
337   {HB_TAG('i','n','i','t'), F_NONE},
338   {HB_TAG('p','r','e','s'), F_GLOBAL},
339   {HB_TAG('a','b','v','s'), F_GLOBAL},
340   {HB_TAG('b','l','w','s'), F_GLOBAL},
341   {HB_TAG('p','s','t','s'), F_GLOBAL},
342   {HB_TAG('h','a','l','n'), F_GLOBAL},
343   /* Positioning features, though we don't care about the types. */
344   {HB_TAG('d','i','s','t'), F_GLOBAL},
345   {HB_TAG('a','b','v','m'), F_GLOBAL},
346   {HB_TAG('b','l','w','m'), F_GLOBAL},
347 };
348 
349 /*
350  * Must be in the same order as the indic_features array.
351  */
352 enum {
353   _NUKT,
354   _AKHN,
355   RPHF,
356   _RKRF,
357   PREF,
358   BLWF,
359   ABVF,
360   HALF,
361   PSTF,
362   _VATU,
363   _CJCT,
364   CFAR,
365 
366   INIT,
367   _PRES,
368   _ABVS,
369   _BLWS,
370   _PSTS,
371   _HALN,
372   _DIST,
373   _ABVM,
374   _BLWM,
375 
376   INDIC_NUM_FEATURES,
377   INDIC_BASIC_FEATURES = INIT /* Don't forget to update this! */
378 };
379 
380 static void
381 setup_syllables (const hb_ot_shape_plan_t *plan,
382 		 hb_font_t *font,
383 		 hb_buffer_t *buffer);
384 static void
385 initial_reordering (const hb_ot_shape_plan_t *plan,
386 		    hb_font_t *font,
387 		    hb_buffer_t *buffer);
388 static void
389 final_reordering (const hb_ot_shape_plan_t *plan,
390 		  hb_font_t *font,
391 		  hb_buffer_t *buffer);
392 static void
393 clear_syllables (const hb_ot_shape_plan_t *plan,
394 		 hb_font_t *font,
395 		 hb_buffer_t *buffer);
396 
397 static void
collect_features_indic(hb_ot_shape_planner_t * plan)398 collect_features_indic (hb_ot_shape_planner_t *plan)
399 {
400   hb_ot_map_builder_t *map = &plan->map;
401 
402   /* Do this before any lookups have been applied. */
403   map->add_gsub_pause (setup_syllables);
404 
405   map->add_global_bool_feature (HB_TAG('l','o','c','l'));
406   /* The Indic specs do not require ccmp, but we apply it here since if
407    * there is a use of it, it's typically at the beginning. */
408   map->add_global_bool_feature (HB_TAG('c','c','m','p'));
409 
410 
411   unsigned int i = 0;
412   map->add_gsub_pause (initial_reordering);
413   for (; i < INDIC_BASIC_FEATURES; i++) {
414     map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ);
415     map->add_gsub_pause (NULL);
416   }
417   map->add_gsub_pause (final_reordering);
418   for (; i < INDIC_NUM_FEATURES; i++) {
419     map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ);
420   }
421 
422   map->add_global_bool_feature (HB_TAG('c','a','l','t'));
423   map->add_global_bool_feature (HB_TAG('c','l','i','g'));
424 
425   map->add_gsub_pause (clear_syllables);
426 }
427 
428 static void
override_features_indic(hb_ot_shape_planner_t * plan)429 override_features_indic (hb_ot_shape_planner_t *plan)
430 {
431   /* Uniscribe does not apply 'kern' in Khmer. */
432   if (hb_options ().uniscribe_bug_compatible)
433   {
434     switch ((hb_tag_t) plan->props.script)
435     {
436       case HB_SCRIPT_KHMER:
437 	plan->map.add_feature (HB_TAG('k','e','r','n'), 0, F_GLOBAL);
438 	break;
439     }
440   }
441 
442   plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);
443 }
444 
445 
446 struct would_substitute_feature_t
447 {
initwould_substitute_feature_t448   inline void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
449   {
450     zero_context = zero_context_;
451     map->get_stage_lookups (0/*GSUB*/,
452 			    map->get_feature_stage (0/*GSUB*/, feature_tag),
453 			    &lookups, &count);
454   }
455 
would_substitutewould_substitute_feature_t456   inline bool would_substitute (const hb_codepoint_t *glyphs,
457 				unsigned int          glyphs_count,
458 				hb_face_t            *face) const
459   {
460     for (unsigned int i = 0; i < count; i++)
461       if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
462 	return true;
463     return false;
464   }
465 
466   private:
467   const hb_ot_map_t::lookup_map_t *lookups;
468   unsigned int count;
469   bool zero_context;
470 };
471 
472 struct indic_shape_plan_t
473 {
474   ASSERT_POD ();
475 
get_virama_glyphindic_shape_plan_t476   inline bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
477   {
478     hb_codepoint_t glyph = virama_glyph;
479     if (unlikely (virama_glyph == (hb_codepoint_t) -1))
480     {
481       if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
482 	glyph = 0;
483       /* Technically speaking, the spec says we should apply 'locl' to virama too.
484        * Maybe one day... */
485 
486       /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
487        * during shape planning...  Instead, overwrite it here.  It's safe.  Don't worry! */
488       (const_cast<indic_shape_plan_t *> (this))->virama_glyph = glyph;
489     }
490 
491     *pglyph = glyph;
492     return glyph != 0;
493   }
494 
495   const indic_config_t *config;
496 
497   bool is_old_spec;
498   hb_codepoint_t virama_glyph;
499 
500   would_substitute_feature_t rphf;
501   would_substitute_feature_t pref;
502   would_substitute_feature_t blwf;
503   would_substitute_feature_t pstf;
504 
505   hb_mask_t mask_array[INDIC_NUM_FEATURES];
506 };
507 
508 static void *
data_create_indic(const hb_ot_shape_plan_t * plan)509 data_create_indic (const hb_ot_shape_plan_t *plan)
510 {
511   indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
512   if (unlikely (!indic_plan))
513     return NULL;
514 
515   indic_plan->config = &indic_configs[0];
516   for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
517     if (plan->props.script == indic_configs[i].script) {
518       indic_plan->config = &indic_configs[i];
519       break;
520     }
521 
522   indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
523   indic_plan->virama_glyph = (hb_codepoint_t) -1;
524 
525   /* Use zero-context would_substitute() matching for new-spec of the main
526    * Indic scripts, and scripts with one spec only, but not for old-specs.
527    * The new-spec for all dual-spec scripts says zero-context matching happens.
528    *
529    * However, testing with Malayalam shows that old and new spec both allow
530    * context.  Testing with Bengali new-spec however shows that it doesn't.
531    * So, the heuristic here is the way it is.  It should *only* be changed,
532    * as we discover more cases of what Windows does.  DON'T TOUCH OTHERWISE.
533    */
534   bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
535   indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
536   indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
537   indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
538   indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
539 
540   for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
541     indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
542 				 0 : plan->map.get_1_mask (indic_features[i].tag);
543 
544   return indic_plan;
545 }
546 
547 static void
data_destroy_indic(void * data)548 data_destroy_indic (void *data)
549 {
550   free (data);
551 }
552 
553 static indic_position_t
consonant_position_from_face(const indic_shape_plan_t * indic_plan,const hb_codepoint_t consonant,const hb_codepoint_t virama,hb_face_t * face)554 consonant_position_from_face (const indic_shape_plan_t *indic_plan,
555 			      const hb_codepoint_t consonant,
556 			      const hb_codepoint_t virama,
557 			      hb_face_t *face)
558 {
559   /* For old-spec, the order of glyphs is Consonant,Virama,
560    * whereas for new-spec, it's Virama,Consonant.  However,
561    * some broken fonts (like Free Sans) simply copied lookups
562    * from old-spec to new-spec without modification.
563    * And oddly enough, Uniscribe seems to respect those lookups.
564    * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
565    * base at 0.  The font however, only has lookups matching
566    * 930,94D in 'blwf', not the expected 94D,930 (with new-spec
567    * table).  As such, we simply match both sequences.  Seems
568    * to work. */
569   hb_codepoint_t glyphs[3] = {virama, consonant, virama};
570   if (indic_plan->blwf.would_substitute (glyphs  , 2, face) ||
571       indic_plan->blwf.would_substitute (glyphs+1, 2, face))
572     return POS_BELOW_C;
573   if (indic_plan->pstf.would_substitute (glyphs  , 2, face) ||
574       indic_plan->pstf.would_substitute (glyphs+1, 2, face))
575     return POS_POST_C;
576   if (indic_plan->pref.would_substitute (glyphs  , 2, face) ||
577       indic_plan->pref.would_substitute (glyphs+1, 2, face))
578     return POS_POST_C;
579   return POS_BASE_C;
580 }
581 
582 
583 enum syllable_type_t {
584   consonant_syllable,
585   vowel_syllable,
586   standalone_cluster,
587   symbol_cluster,
588   broken_cluster,
589   non_indic_cluster,
590 };
591 
592 #include "hb-ot-shape-complex-indic-machine.hh"
593 
594 
595 static void
setup_masks_indic(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_buffer_t * buffer,hb_font_t * font HB_UNUSED)596 setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
597 		   hb_buffer_t              *buffer,
598 		   hb_font_t                *font HB_UNUSED)
599 {
600   HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
601   HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
602 
603   /* We cannot setup masks here.  We save information about characters
604    * and setup masks later on in a pause-callback. */
605 
606   unsigned int count = buffer->len;
607   hb_glyph_info_t *info = buffer->info;
608   for (unsigned int i = 0; i < count; i++)
609     set_indic_properties (info[i]);
610 }
611 
612 static void
setup_syllables(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font HB_UNUSED,hb_buffer_t * buffer)613 setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
614 		 hb_font_t *font HB_UNUSED,
615 		 hb_buffer_t *buffer)
616 {
617   find_syllables (buffer);
618 }
619 
620 static int
compare_indic_order(const hb_glyph_info_t * pa,const hb_glyph_info_t * pb)621 compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
622 {
623   int a = pa->indic_position();
624   int b = pb->indic_position();
625 
626   return a < b ? -1 : a == b ? 0 : +1;
627 }
628 
629 
630 
631 static void
update_consonant_positions(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)632 update_consonant_positions (const hb_ot_shape_plan_t *plan,
633 			    hb_font_t         *font,
634 			    hb_buffer_t       *buffer)
635 {
636   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
637 
638   if (indic_plan->config->base_pos != BASE_POS_LAST)
639     return;
640 
641   hb_codepoint_t virama;
642   if (indic_plan->get_virama_glyph (font, &virama))
643   {
644     hb_face_t *face = font->face;
645     unsigned int count = buffer->len;
646     hb_glyph_info_t *info = buffer->info;
647     for (unsigned int i = 0; i < count; i++)
648       if (info[i].indic_position() == POS_BASE_C)
649       {
650 	hb_codepoint_t consonant = info[i].codepoint;
651 	info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
652       }
653   }
654 }
655 
656 
657 /* Rules from:
658  * https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx */
659 
660 static void
initial_reordering_consonant_syllable(const hb_ot_shape_plan_t * plan,hb_face_t * face,hb_buffer_t * buffer,unsigned int start,unsigned int end)661 initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
662 				       hb_face_t *face,
663 				       hb_buffer_t *buffer,
664 				       unsigned int start, unsigned int end)
665 {
666   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
667   hb_glyph_info_t *info = buffer->info;
668 
669 
670   /* 1. Find base consonant:
671    *
672    * The shaping engine finds the base consonant of the syllable, using the
673    * following algorithm: starting from the end of the syllable, move backwards
674    * until a consonant is found that does not have a below-base or post-base
675    * form (post-base forms have to follow below-base forms), or that is not a
676    * pre-base reordering Ra, or arrive at the first consonant. The consonant
677    * stopped at will be the base.
678    *
679    *   o If the syllable starts with Ra + Halant (in a script that has Reph)
680    *     and has more than one consonant, Ra is excluded from candidates for
681    *     base consonants.
682    */
683 
684   unsigned int base = end;
685   bool has_reph = false;
686 
687   {
688     /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
689      *    and has more than one consonant, Ra is excluded from candidates for
690      *    base consonants. */
691     unsigned int limit = start;
692     if (indic_plan->config->reph_pos != REPH_POS_DONT_CARE &&
693 	indic_plan->mask_array[RPHF] &&
694 	start + 3 <= end &&
695 	(
696 	 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
697 	 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
698 	))
699     {
700       /* See if it matches the 'rphf' feature. */
701       hb_codepoint_t glyphs[3] = {info[start].codepoint,
702 				  info[start + 1].codepoint,
703 				  indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
704 				    info[start + 2].codepoint : 0};
705       if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
706 	  (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
707 	   indic_plan->rphf.would_substitute (glyphs, 3, face)))
708       {
709 	limit += 2;
710 	while (limit < end && is_joiner (info[limit]))
711 	  limit++;
712 	base = start;
713 	has_reph = true;
714       }
715     } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
716     {
717 	limit += 1;
718 	while (limit < end && is_joiner (info[limit]))
719 	  limit++;
720 	base = start;
721 	has_reph = true;
722     }
723 
724     switch (indic_plan->config->base_pos)
725     {
726       case BASE_POS_LAST:
727       {
728 	/* -> starting from the end of the syllable, move backwards */
729 	unsigned int i = end;
730 	bool seen_below = false;
731 	do {
732 	  i--;
733 	  /* -> until a consonant is found */
734 	  if (is_consonant (info[i]))
735 	  {
736 	    /* -> that does not have a below-base or post-base form
737 	     * (post-base forms have to follow below-base forms), */
738 	    if (info[i].indic_position() != POS_BELOW_C &&
739 		(info[i].indic_position() != POS_POST_C || seen_below))
740 	    {
741 	      base = i;
742 	      break;
743 	    }
744 	    if (info[i].indic_position() == POS_BELOW_C)
745 	      seen_below = true;
746 
747 	    /* -> or that is not a pre-base reordering Ra,
748 	     *
749 	     * IMPLEMENTATION NOTES:
750 	     *
751 	     * Our pre-base reordering Ra's are marked POS_POST_C, so will be skipped
752 	     * by the logic above already.
753 	     */
754 
755 	    /* -> or arrive at the first consonant. The consonant stopped at will
756 	     * be the base. */
757 	    base = i;
758 	  }
759 	  else
760 	  {
761 	    /* A ZWJ after a Halant stops the base search, and requests an explicit
762 	     * half form.
763 	     * A ZWJ before a Halant, requests a subjoined form instead, and hence
764 	     * search continues.  This is particularly important for Bengali
765 	     * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
766 	    if (start < i &&
767 		info[i].indic_category() == OT_ZWJ &&
768 		info[i - 1].indic_category() == OT_H)
769 	      break;
770 	  }
771 	} while (i > limit);
772       }
773       break;
774 
775       case BASE_POS_LAST_SINHALA:
776       {
777         /* Sinhala base positioning is slightly different from main Indic, in that:
778 	 * 1. Its ZWJ behavior is different,
779 	 * 2. We don't need to look into the font for consonant positions.
780 	 */
781 
782 	if (!has_reph)
783 	  base = limit;
784 
785 	/* Find the last base consonant that is not blocked by ZWJ.  If there is
786 	 * a ZWJ right before a base consonant, that would request a subjoined form. */
787 	for (unsigned int i = limit; i < end; i++)
788 	  if (is_consonant (info[i]))
789 	  {
790 	    if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
791 	      break;
792 	    else
793 	      base = i;
794 	  }
795 
796 	/* Mark all subsequent consonants as below. */
797 	for (unsigned int i = base + 1; i < end; i++)
798 	  if (is_consonant (info[i]))
799 	    info[i].indic_position() = POS_BELOW_C;
800       }
801       break;
802 
803       case BASE_POS_FIRST:
804       {
805 	/* The first consonant is always the base. */
806 
807 	assert (indic_plan->config->reph_mode == REPH_MODE_VIS_REPHA);
808 	assert (!has_reph);
809 
810 	base = start;
811 
812 	/* Mark all subsequent consonants as below. */
813 	for (unsigned int i = base + 1; i < end; i++)
814 	  if (is_consonant (info[i]))
815 	    info[i].indic_position() = POS_BELOW_C;
816       }
817       break;
818     }
819 
820     /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
821      *    and has more than one consonant, Ra is excluded from candidates for
822      *    base consonants.
823      *
824      *  Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
825     if (has_reph && base == start && limit - base <= 2) {
826       /* Have no other consonant, so Reph is not formed and Ra becomes base. */
827       has_reph = false;
828     }
829   }
830 
831 
832   /* 2. Decompose and reorder Matras:
833    *
834    * Each matra and any syllable modifier sign in the cluster are moved to the
835    * appropriate position relative to the consonant(s) in the cluster. The
836    * shaping engine decomposes two- or three-part matras into their constituent
837    * parts before any repositioning. Matra characters are classified by which
838    * consonant in a conjunct they have affinity for and are reordered to the
839    * following positions:
840    *
841    *   o Before first half form in the syllable
842    *   o After subjoined consonants
843    *   o After post-form consonant
844    *   o After main consonant (for above marks)
845    *
846    * IMPLEMENTATION NOTES:
847    *
848    * The normalize() routine has already decomposed matras for us, so we don't
849    * need to worry about that.
850    */
851 
852 
853   /* 3.  Reorder marks to canonical order:
854    *
855    * Adjacent nukta and halant or nukta and vedic sign are always repositioned
856    * if necessary, so that the nukta is first.
857    *
858    * IMPLEMENTATION NOTES:
859    *
860    * We don't need to do this: the normalize() routine already did this for us.
861    */
862 
863 
864   /* Reorder characters */
865 
866   for (unsigned int i = start; i < base; i++)
867     info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
868 
869   if (base < end)
870     info[base].indic_position() = POS_BASE_C;
871 
872   /* Mark final consonants.  A final consonant is one appearing after a matra,
873    * like in Khmer. */
874   for (unsigned int i = base + 1; i < end; i++)
875     if (info[i].indic_category() == OT_M) {
876       for (unsigned int j = i + 1; j < end; j++)
877         if (is_consonant (info[j])) {
878 	  info[j].indic_position() = POS_FINAL_C;
879 	  break;
880 	}
881       break;
882     }
883 
884   /* Handle beginning Ra */
885   if (has_reph)
886     info[start].indic_position() = POS_RA_TO_BECOME_REPH;
887 
888   /* For old-style Indic script tags, move the first post-base Halant after
889    * last consonant.
890    *
891    * Reports suggest that in some scripts Uniscribe does this only if there
892    * is *not* a Halant after last consonant already (eg. Kannada), while it
893    * does it unconditionally in other scripts (eg. Malayalam).  We don't
894    * currently know about other scripts, so we single out Malayalam for now.
895    *
896    * Kannada test case:
897    * U+0C9A,U+0CCD,U+0C9A,U+0CCD
898    * With some versions of Lohit Kannada.
899    * https://bugs.freedesktop.org/show_bug.cgi?id=59118
900    *
901    * Malayalam test case:
902    * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
903    * With lohit-ttf-20121122/Lohit-Malayalam.ttf
904    */
905   if (indic_plan->is_old_spec)
906   {
907     bool disallow_double_halants = buffer->props.script != HB_SCRIPT_MALAYALAM;
908     for (unsigned int i = base + 1; i < end; i++)
909       if (info[i].indic_category() == OT_H)
910       {
911         unsigned int j;
912         for (j = end - 1; j > i; j--)
913 	  if (is_consonant (info[j]) ||
914 	      (disallow_double_halants && info[j].indic_category() == OT_H))
915 	    break;
916 	if (info[j].indic_category() != OT_H && j > i) {
917 	  /* Move Halant to after last consonant. */
918 	  hb_glyph_info_t t = info[i];
919 	  memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
920 	  info[j] = t;
921 	}
922         break;
923       }
924   }
925 
926   /* Attach misc marks to previous char to move with them. */
927   {
928     indic_position_t last_pos = POS_START;
929     for (unsigned int i = start; i < end; i++)
930     {
931       if ((FLAG_SAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | HALANT_OR_COENG_FLAGS)))
932       {
933 	info[i].indic_position() = last_pos;
934 	if (unlikely (info[i].indic_category() == OT_H &&
935 		      info[i].indic_position() == POS_PRE_M))
936 	{
937 	  /*
938 	   * Uniscribe doesn't move the Halant with Left Matra.
939 	   * TEST: U+092B,U+093F,U+094DE
940 	   * We follow.  This is important for the Sinhala
941 	   * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
942 	   * where U+0DD9 is a left matra and U+0DCA is the virama.
943 	   * We don't want to move the virama with the left matra.
944 	   * TEST: U+0D9A,U+0DDA
945 	   */
946 	  for (unsigned int j = i; j > start; j--)
947 	    if (info[j - 1].indic_position() != POS_PRE_M) {
948 	      info[i].indic_position() = info[j - 1].indic_position();
949 	      break;
950 	    }
951 	}
952       } else if (info[i].indic_position() != POS_SMVD) {
953         last_pos = (indic_position_t) info[i].indic_position();
954       }
955     }
956   }
957   /* For post-base consonants let them own anything before them
958    * since the last consonant or matra. */
959   {
960     unsigned int last = base;
961     for (unsigned int i = base + 1; i < end; i++)
962       if (is_consonant (info[i]))
963       {
964 	for (unsigned int j = last + 1; j < i; j++)
965 	  if (info[j].indic_position() < POS_SMVD)
966 	    info[j].indic_position() = info[i].indic_position();
967 	last = i;
968       } else if (info[i].indic_category() == OT_M)
969         last = i;
970   }
971 
972 
973   {
974     /* Use syllable() for sort accounting temporarily. */
975     unsigned int syllable = info[start].syllable();
976     for (unsigned int i = start; i < end; i++)
977       info[i].syllable() = i - start;
978 
979     /* Sit tight, rock 'n roll! */
980     hb_stable_sort (info + start, end - start, compare_indic_order);
981     /* Find base again */
982     base = end;
983     for (unsigned int i = start; i < end; i++)
984       if (info[i].indic_position() == POS_BASE_C)
985       {
986 	base = i;
987 	break;
988       }
989     /* Things are out-of-control for post base positions, they may shuffle
990      * around like crazy.  In old-spec mode, we move halants around, so in
991      * that case merge all clusters after base.  Otherwise, check the sort
992      * order and merge as needed.
993      * For pre-base stuff, we handle cluster issues in final reordering.
994      *
995      * We could use buffer->sort() for this, if there was no special
996      * reordering of pre-base stuff happening later...
997      */
998     if (indic_plan->is_old_spec || end - base > 127)
999       buffer->merge_clusters (base, end);
1000     else
1001     {
1002       /* Note!  syllable() is a one-byte field. */
1003       for (unsigned int i = base; i < end; i++)
1004         if (info[i].syllable() != 255)
1005 	{
1006 	  unsigned int max = i;
1007 	  unsigned int j = start + info[i].syllable();
1008 	  while (j != i)
1009 	  {
1010 	    max = MAX (max, j);
1011 	    unsigned int next = start + info[j].syllable();
1012 	    info[j].syllable() = 255; /* So we don't process j later again. */
1013 	    j = next;
1014 	  }
1015 	  if (i != max)
1016 	    buffer->merge_clusters (i, max + 1);
1017 	}
1018     }
1019 
1020     /* Put syllable back in. */
1021     for (unsigned int i = start; i < end; i++)
1022       info[i].syllable() = syllable;
1023   }
1024 
1025   /* Setup masks now */
1026 
1027   {
1028     hb_mask_t mask;
1029 
1030     /* Reph */
1031     for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
1032       info[i].mask |= indic_plan->mask_array[RPHF];
1033 
1034     /* Pre-base */
1035     mask = indic_plan->mask_array[HALF];
1036     if (!indic_plan->is_old_spec &&
1037 	indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
1038       mask |= indic_plan->mask_array[BLWF];
1039     for (unsigned int i = start; i < base; i++)
1040       info[i].mask  |= mask;
1041     /* Base */
1042     mask = 0;
1043     if (base < end)
1044       info[base].mask |= mask;
1045     /* Post-base */
1046     mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
1047     for (unsigned int i = base + 1; i < end; i++)
1048       info[i].mask  |= mask;
1049   }
1050 
1051   if (indic_plan->is_old_spec &&
1052       buffer->props.script == HB_SCRIPT_DEVANAGARI)
1053   {
1054     /* Old-spec eye-lash Ra needs special handling.  From the
1055      * spec:
1056      *
1057      * "The feature 'below-base form' is applied to consonants
1058      * having below-base forms and following the base consonant.
1059      * The exception is vattu, which may appear below half forms
1060      * as well as below the base glyph. The feature 'below-base
1061      * form' will be applied to all such occurrences of Ra as well."
1062      *
1063      * Test case: U+0924,U+094D,U+0930,U+094d,U+0915
1064      * with Sanskrit 2003 font.
1065      *
1066      * However, note that Ra,Halant,ZWJ is the correct way to
1067      * request eyelash form of Ra, so we wouldbn't inhibit it
1068      * in that sequence.
1069      *
1070      * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
1071      */
1072     for (unsigned int i = start; i + 1 < base; i++)
1073       if (info[i  ].indic_category() == OT_Ra &&
1074 	  info[i+1].indic_category() == OT_H  &&
1075 	  (i + 2 == base ||
1076 	   info[i+2].indic_category() != OT_ZWJ))
1077       {
1078 	info[i  ].mask |= indic_plan->mask_array[BLWF];
1079 	info[i+1].mask |= indic_plan->mask_array[BLWF];
1080       }
1081   }
1082 
1083   unsigned int pref_len = 2;
1084   if (indic_plan->mask_array[PREF] && base + pref_len < end)
1085   {
1086     /* Find a Halant,Ra sequence and mark it for pre-base reordering processing. */
1087     for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
1088       hb_codepoint_t glyphs[2];
1089       for (unsigned int j = 0; j < pref_len; j++)
1090         glyphs[j] = info[i + j].codepoint;
1091       if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
1092       {
1093 	for (unsigned int j = 0; j < pref_len; j++)
1094 	  info[i++].mask |= indic_plan->mask_array[PREF];
1095 
1096 	/* Mark the subsequent stuff with 'cfar'.  Used in Khmer.
1097 	 * Read the feature spec.
1098 	 * This allows distinguishing the following cases with MS Khmer fonts:
1099 	 * U+1784,U+17D2,U+179A,U+17D2,U+1782
1100 	 * U+1784,U+17D2,U+1782,U+17D2,U+179A
1101 	 */
1102 	if (indic_plan->mask_array[CFAR])
1103 	  for (; i < end; i++)
1104 	    info[i].mask |= indic_plan->mask_array[CFAR];
1105 
1106 	break;
1107       }
1108     }
1109   }
1110 
1111   /* Apply ZWJ/ZWNJ effects */
1112   for (unsigned int i = start + 1; i < end; i++)
1113     if (is_joiner (info[i])) {
1114       bool non_joiner = info[i].indic_category() == OT_ZWNJ;
1115       unsigned int j = i;
1116 
1117       do {
1118 	j--;
1119 
1120 	/* ZWJ/ZWNJ should disable CJCT.  They do that by simply
1121 	 * being there, since we don't skip them for the CJCT
1122 	 * feature (ie. F_MANUAL_ZWJ) */
1123 
1124 	/* A ZWNJ disables HALF. */
1125 	if (non_joiner)
1126 	  info[j].mask &= ~indic_plan->mask_array[HALF];
1127 
1128       } while (j > start && !is_consonant (info[j]));
1129     }
1130 }
1131 
1132 static void
initial_reordering_standalone_cluster(const hb_ot_shape_plan_t * plan,hb_face_t * face,hb_buffer_t * buffer,unsigned int start,unsigned int end)1133 initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
1134 				       hb_face_t *face,
1135 				       hb_buffer_t *buffer,
1136 				       unsigned int start, unsigned int end)
1137 {
1138   /* We treat placeholder/dotted-circle as if they are consonants, so we
1139    * should just chain.  Only if not in compatibility mode that is... */
1140 
1141   if (hb_options ().uniscribe_bug_compatible)
1142   {
1143     /* For dotted-circle, this is what Uniscribe does:
1144      * If dotted-circle is the last glyph, it just does nothing.
1145      * Ie. It doesn't form Reph. */
1146     if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
1147       return;
1148   }
1149 
1150   initial_reordering_consonant_syllable (plan, face, buffer, start, end);
1151 }
1152 
1153 static void
initial_reordering_syllable(const hb_ot_shape_plan_t * plan,hb_face_t * face,hb_buffer_t * buffer,unsigned int start,unsigned int end)1154 initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
1155 			     hb_face_t *face,
1156 			     hb_buffer_t *buffer,
1157 			     unsigned int start, unsigned int end)
1158 {
1159   syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
1160   switch (syllable_type)
1161   {
1162     case vowel_syllable: /* We made the vowels look like consonants.  So let's call the consonant logic! */
1163     case consonant_syllable:
1164      initial_reordering_consonant_syllable (plan, face, buffer, start, end);
1165      break;
1166 
1167     case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
1168     case standalone_cluster:
1169      initial_reordering_standalone_cluster (plan, face, buffer, start, end);
1170      break;
1171 
1172     case symbol_cluster:
1173     case non_indic_cluster:
1174       break;
1175   }
1176 }
1177 
1178 static inline void
insert_dotted_circles(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font,hb_buffer_t * buffer)1179 insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
1180 		       hb_font_t *font,
1181 		       hb_buffer_t *buffer)
1182 {
1183   /* Note: This loop is extra overhead, but should not be measurable. */
1184   bool has_broken_syllables = false;
1185   unsigned int count = buffer->len;
1186   hb_glyph_info_t *info = buffer->info;
1187   for (unsigned int i = 0; i < count; i++)
1188     if ((info[i].syllable() & 0x0F) == broken_cluster)
1189     {
1190       has_broken_syllables = true;
1191       break;
1192     }
1193   if (likely (!has_broken_syllables))
1194     return;
1195 
1196 
1197   hb_codepoint_t dottedcircle_glyph;
1198   if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
1199     return;
1200 
1201   hb_glyph_info_t dottedcircle = {0};
1202   dottedcircle.codepoint = 0x25CCu;
1203   set_indic_properties (dottedcircle);
1204   dottedcircle.codepoint = dottedcircle_glyph;
1205 
1206   buffer->clear_output ();
1207 
1208   buffer->idx = 0;
1209   unsigned int last_syllable = 0;
1210   while (buffer->idx < buffer->len && !buffer->in_error)
1211   {
1212     unsigned int syllable = buffer->cur().syllable();
1213     syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
1214     if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
1215     {
1216       last_syllable = syllable;
1217 
1218       hb_glyph_info_t ginfo = dottedcircle;
1219       ginfo.cluster = buffer->cur().cluster;
1220       ginfo.mask = buffer->cur().mask;
1221       ginfo.syllable() = buffer->cur().syllable();
1222       /* TODO Set glyph_props? */
1223 
1224       /* Insert dottedcircle after possible Repha. */
1225       while (buffer->idx < buffer->len && !buffer->in_error &&
1226 	     last_syllable == buffer->cur().syllable() &&
1227 	     buffer->cur().indic_category() == OT_Repha)
1228         buffer->next_glyph ();
1229 
1230       buffer->output_info (ginfo);
1231     }
1232     else
1233       buffer->next_glyph ();
1234   }
1235 
1236   buffer->swap_buffers ();
1237 }
1238 
1239 static void
initial_reordering(const hb_ot_shape_plan_t * plan,hb_font_t * font,hb_buffer_t * buffer)1240 initial_reordering (const hb_ot_shape_plan_t *plan,
1241 		    hb_font_t *font,
1242 		    hb_buffer_t *buffer)
1243 {
1244   update_consonant_positions (plan, font, buffer);
1245   insert_dotted_circles (plan, font, buffer);
1246 
1247   foreach_syllable (buffer, start, end)
1248     initial_reordering_syllable (plan, font->face, buffer, start, end);
1249 }
1250 
1251 static void
final_reordering_syllable(const hb_ot_shape_plan_t * plan,hb_buffer_t * buffer,unsigned int start,unsigned int end)1252 final_reordering_syllable (const hb_ot_shape_plan_t *plan,
1253 			   hb_buffer_t *buffer,
1254 			   unsigned int start, unsigned int end)
1255 {
1256   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
1257   hb_glyph_info_t *info = buffer->info;
1258 
1259 
1260   /* This function relies heavily on halant glyphs.  Lots of ligation
1261    * and possibly multiplication substitutions happened prior to this
1262    * phase, and that might have messed up our properties.  Recover
1263    * from a particular case of that where we're fairly sure that a
1264    * class of OT_H is desired but has been lost. */
1265   if (indic_plan->virama_glyph)
1266   {
1267     unsigned int virama_glyph = indic_plan->virama_glyph;
1268     for (unsigned int i = start; i < end; i++)
1269       if (info[i].codepoint == virama_glyph &&
1270 	  _hb_glyph_info_ligated (&info[i]) &&
1271 	  _hb_glyph_info_multiplied (&info[i]))
1272       {
1273         /* This will make sure that this glyph passes is_halant_or_coeng() test. */
1274 	info[i].indic_category() = OT_H;
1275 	_hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
1276       }
1277   }
1278 
1279 
1280   /* 4. Final reordering:
1281    *
1282    * After the localized forms and basic shaping forms GSUB features have been
1283    * applied (see below), the shaping engine performs some final glyph
1284    * reordering before applying all the remaining font features to the entire
1285    * cluster.
1286    */
1287 
1288   bool try_pref = !!indic_plan->mask_array[PREF];
1289 
1290   /* Find base again */
1291   unsigned int base;
1292   for (base = start; base < end; base++)
1293     if (info[base].indic_position() >= POS_BASE_C)
1294     {
1295       if (try_pref && base + 1 < end)
1296       {
1297 	for (unsigned int i = base + 1; i < end; i++)
1298 	  if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1299 	  {
1300 	    if (!(_hb_glyph_info_substituted (&info[i]) &&
1301 		  _hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
1302 	    {
1303 	      /* Ok, this was a 'pref' candidate but didn't form any.
1304 	       * Base is around here... */
1305 	      base = i;
1306 	      while (base < end && is_halant_or_coeng (info[base]))
1307 		base++;
1308 	      info[base].indic_position() = POS_BASE_C;
1309 
1310 	      try_pref = false;
1311 	    }
1312 	    break;
1313 	  }
1314       }
1315       /* For Malayalam, skip over unformed below- (but NOT post-) forms. */
1316       if (buffer->props.script == HB_SCRIPT_MALAYALAM)
1317       {
1318 	for (unsigned int i = base + 1; i < end; i++)
1319 	{
1320 	  while (i < end && is_joiner (info[i]))
1321 	    i++;
1322 	  if (i == end || !is_halant_or_coeng (info[i]))
1323 	    break;
1324 	  i++; /* Skip halant. */
1325 	  while (i < end && is_joiner (info[i]))
1326 	    i++;
1327 	  if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
1328 	  {
1329 	    base = i;
1330 	    info[base].indic_position() = POS_BASE_C;
1331 	  }
1332 	}
1333       }
1334 
1335       if (start < base && info[base].indic_position() > POS_BASE_C)
1336         base--;
1337       break;
1338     }
1339   if (base == end && start < base &&
1340       is_one_of (info[base - 1], FLAG (OT_ZWJ)))
1341     base--;
1342   if (base < end)
1343     while (start < base &&
1344 	   is_one_of (info[base], (FLAG (OT_N) | HALANT_OR_COENG_FLAGS)))
1345       base--;
1346 
1347 
1348   /*   o Reorder matras:
1349    *
1350    *     If a pre-base matra character had been reordered before applying basic
1351    *     features, the glyph can be moved closer to the main consonant based on
1352    *     whether half-forms had been formed. Actual position for the matra is
1353    *     defined as “after last standalone halant glyph, after initial matra
1354    *     position and before the main consonant”. If ZWJ or ZWNJ follow this
1355    *     halant, position is moved after it.
1356    */
1357 
1358   if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
1359   {
1360     /* If we lost track of base, alas, position before last thingy. */
1361     unsigned int new_pos = base == end ? base - 2 : base - 1;
1362 
1363     /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1364      * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1365      * We want to position matra after them.
1366      */
1367     if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1368     {
1369       while (new_pos > start &&
1370 	     !(is_one_of (info[new_pos], (FLAG (OT_M) | HALANT_OR_COENG_FLAGS))))
1371 	new_pos--;
1372 
1373       /* If we found no Halant we are done.
1374        * Otherwise only proceed if the Halant does
1375        * not belong to the Matra itself! */
1376       if (is_halant_or_coeng (info[new_pos]) &&
1377 	  info[new_pos].indic_position() != POS_PRE_M)
1378       {
1379 	/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1380 	if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
1381 	  new_pos++;
1382       }
1383       else
1384         new_pos = start; /* No move. */
1385     }
1386 
1387     if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
1388     {
1389       /* Now go see if there's actually any matras... */
1390       for (unsigned int i = new_pos; i > start; i--)
1391 	if (info[i - 1].indic_position () == POS_PRE_M)
1392 	{
1393 	  unsigned int old_pos = i - 1;
1394 	  if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
1395 	    base--;
1396 
1397 	  hb_glyph_info_t tmp = info[old_pos];
1398 	  memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
1399 	  info[new_pos] = tmp;
1400 
1401 	  /* Note: this merge_clusters() is intentionally *after* the reordering.
1402 	   * Indic matra reordering is special and tricky... */
1403 	  buffer->merge_clusters (new_pos, MIN (end, base + 1));
1404 
1405 	  new_pos--;
1406 	}
1407     } else {
1408       for (unsigned int i = start; i < base; i++)
1409 	if (info[i].indic_position () == POS_PRE_M) {
1410 	  buffer->merge_clusters (i, MIN (end, base + 1));
1411 	  break;
1412 	}
1413     }
1414   }
1415 
1416 
1417   /*   o Reorder reph:
1418    *
1419    *     Reph’s original position is always at the beginning of the syllable,
1420    *     (i.e. it is not reordered at the character reordering stage). However,
1421    *     it will be reordered according to the basic-forms shaping results.
1422    *     Possible positions for reph, depending on the script, are; after main,
1423    *     before post-base consonant forms, and after post-base consonant forms.
1424    */
1425 
1426   /* Two cases:
1427    *
1428    * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
1429    *   we should only move it if the sequence ligated to the repha form.
1430    *
1431    * - If repha is encoded separately and in the logical position, we should only
1432    *   move it if it did NOT ligate.  If it ligated, it's probably the font trying
1433    *   to make it work without the reordering.
1434    */
1435   if (start + 1 < end &&
1436       info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
1437       ((info[start].indic_category() == OT_Repha) ^
1438        _hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
1439   {
1440     unsigned int new_reph_pos;
1441     reph_position_t reph_pos = indic_plan->config->reph_pos;
1442 
1443     assert (reph_pos != REPH_POS_DONT_CARE);
1444 
1445     /*       1. If reph should be positioned after post-base consonant forms,
1446      *          proceed to step 5.
1447      */
1448     if (reph_pos == REPH_POS_AFTER_POST)
1449     {
1450       goto reph_step_5;
1451     }
1452 
1453     /*       2. If the reph repositioning class is not after post-base: target
1454      *          position is after the first explicit halant glyph between the
1455      *          first post-reph consonant and last main consonant. If ZWJ or ZWNJ
1456      *          are following this halant, position is moved after it. If such
1457      *          position is found, this is the target position. Otherwise,
1458      *          proceed to the next step.
1459      *
1460      *          Note: in old-implementation fonts, where classifications were
1461      *          fixed in shaping engine, there was no case where reph position
1462      *          will be found on this step.
1463      */
1464     {
1465       new_reph_pos = start + 1;
1466       while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
1467 	new_reph_pos++;
1468 
1469       if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
1470       {
1471 	/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1472 	if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1473 	  new_reph_pos++;
1474 	goto reph_move;
1475       }
1476     }
1477 
1478     /*       3. If reph should be repositioned after the main consonant: find the
1479      *          first consonant not ligated with main, or find the first
1480      *          consonant that is not a potential pre-base reordering Ra.
1481      */
1482     if (reph_pos == REPH_POS_AFTER_MAIN)
1483     {
1484       new_reph_pos = base;
1485       while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
1486 	new_reph_pos++;
1487       if (new_reph_pos < end)
1488         goto reph_move;
1489     }
1490 
1491     /*       4. If reph should be positioned before post-base consonant, find
1492      *          first post-base classified consonant not ligated with main. If no
1493      *          consonant is found, the target position should be before the
1494      *          first matra, syllable modifier sign or vedic sign.
1495      */
1496     /* This is our take on what step 4 is trying to say (and failing, BADLY). */
1497     if (reph_pos == REPH_POS_AFTER_SUB)
1498     {
1499       new_reph_pos = base;
1500       while (new_reph_pos < end &&
1501 	     !( FLAG_SAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
1502 	new_reph_pos++;
1503       if (new_reph_pos < end)
1504         goto reph_move;
1505     }
1506 
1507     /*       5. If no consonant is found in steps 3 or 4, move reph to a position
1508      *          immediately before the first post-base matra, syllable modifier
1509      *          sign or vedic sign that has a reordering class after the intended
1510      *          reph position. For example, if the reordering position for reph
1511      *          is post-main, it will skip above-base matras that also have a
1512      *          post-main position.
1513      */
1514     reph_step_5:
1515     {
1516       /* Copied from step 2. */
1517       new_reph_pos = start + 1;
1518       while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
1519 	new_reph_pos++;
1520 
1521       if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
1522       {
1523 	/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
1524 	if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
1525 	  new_reph_pos++;
1526 	goto reph_move;
1527       }
1528     }
1529 
1530     /*       6. Otherwise, reorder reph to the end of the syllable.
1531      */
1532     {
1533       new_reph_pos = end - 1;
1534       while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
1535 	new_reph_pos--;
1536 
1537       /*
1538        * If the Reph is to be ending up after a Matra,Halant sequence,
1539        * position it before that Halant so it can interact with the Matra.
1540        * However, if it's a plain Consonant,Halant we shouldn't do that.
1541        * Uniscribe doesn't do this.
1542        * TEST: U+0930,U+094D,U+0915,U+094B,U+094D
1543        */
1544       if (!hb_options ().uniscribe_bug_compatible &&
1545 	  unlikely (is_halant_or_coeng (info[new_reph_pos]))) {
1546 	for (unsigned int i = base + 1; i < new_reph_pos; i++)
1547 	  if (info[i].indic_category() == OT_M) {
1548 	    /* Ok, got it. */
1549 	    new_reph_pos--;
1550 	  }
1551       }
1552       goto reph_move;
1553     }
1554 
1555     reph_move:
1556     {
1557       /* Move */
1558       buffer->merge_clusters (start, new_reph_pos + 1);
1559       hb_glyph_info_t reph = info[start];
1560       memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
1561       info[new_reph_pos] = reph;
1562 
1563       if (start < base && base <= new_reph_pos)
1564 	base--;
1565     }
1566   }
1567 
1568 
1569   /*   o Reorder pre-base reordering consonants:
1570    *
1571    *     If a pre-base reordering consonant is found, reorder it according to
1572    *     the following rules:
1573    */
1574 
1575   if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base reordering Ra. */
1576   {
1577     for (unsigned int i = base + 1; i < end; i++)
1578       if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
1579       {
1580 	/*       1. Only reorder a glyph produced by substitution during application
1581 	 *          of the <pref> feature. (Note that a font may shape a Ra consonant with
1582 	 *          the feature generally but block it in certain contexts.)
1583 	 */
1584         /* Note: We just check that something got substituted.  We don't check that
1585 	 * the <pref> feature actually did it...
1586 	 *
1587 	 * Reorder pref only if it ligated. */
1588 	if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
1589 	{
1590 	  /*
1591 	   *       2. Try to find a target position the same way as for pre-base matra.
1592 	   *          If it is found, reorder pre-base consonant glyph.
1593 	   *
1594 	   *       3. If position is not found, reorder immediately before main
1595 	   *          consonant.
1596 	   */
1597 
1598 	  unsigned int new_pos = base;
1599 	  /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
1600 	   * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
1601 	   * We want to position matra after them.
1602 	   */
1603 	  if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
1604 	  {
1605 	    while (new_pos > start &&
1606 		   !(is_one_of (info[new_pos - 1], FLAG(OT_M) | HALANT_OR_COENG_FLAGS)))
1607 	      new_pos--;
1608 
1609 	    /* In Khmer coeng model, a H,Ra can go *after* matras.  If it goes after a
1610 	     * split matra, it should be reordered to *before* the left part of such matra. */
1611 	    if (new_pos > start && info[new_pos - 1].indic_category() == OT_M)
1612 	    {
1613 	      unsigned int old_pos = i;
1614 	      for (unsigned int j = base + 1; j < old_pos; j++)
1615 		if (info[j].indic_category() == OT_M)
1616 		{
1617 		  new_pos--;
1618 		  break;
1619 		}
1620 	    }
1621 	  }
1622 
1623 	  if (new_pos > start && is_halant_or_coeng (info[new_pos - 1]))
1624 	  {
1625 	    /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
1626 	    if (new_pos < end && is_joiner (info[new_pos]))
1627 	      new_pos++;
1628 	  }
1629 
1630 	  {
1631 	    unsigned int old_pos = i;
1632 
1633 	    buffer->merge_clusters (new_pos, old_pos + 1);
1634 	    hb_glyph_info_t tmp = info[old_pos];
1635 	    memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
1636 	    info[new_pos] = tmp;
1637 
1638 	    if (new_pos <= base && base < old_pos)
1639 	      base++;
1640 	  }
1641 	}
1642 
1643         break;
1644       }
1645   }
1646 
1647 
1648   /* Apply 'init' to the Left Matra if it's a word start. */
1649   if (info[start].indic_position () == POS_PRE_M &&
1650       (!start ||
1651        !(FLAG_SAFE (_hb_glyph_info_get_general_category (&info[start - 1])) &
1652 	 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))))
1653     info[start].mask |= indic_plan->mask_array[INIT];
1654 
1655 
1656   /*
1657    * Finish off the clusters and go home!
1658    */
1659   if (hb_options ().uniscribe_bug_compatible)
1660   {
1661     switch ((hb_tag_t) plan->props.script)
1662     {
1663       case HB_SCRIPT_TAMIL:
1664       case HB_SCRIPT_SINHALA:
1665         break;
1666 
1667       default:
1668 	/* Uniscribe merges the entire cluster... Except for Tamil & Sinhala.
1669 	 * This means, half forms are submerged into the main consonants cluster.
1670 	 * This is unnecessary, and makes cursor positioning harder, but that's what
1671 	 * Uniscribe does. */
1672 	buffer->merge_clusters (start, end);
1673 	break;
1674     }
1675   }
1676 }
1677 
1678 
1679 static void
final_reordering(const hb_ot_shape_plan_t * plan,hb_font_t * font HB_UNUSED,hb_buffer_t * buffer)1680 final_reordering (const hb_ot_shape_plan_t *plan,
1681 		  hb_font_t *font HB_UNUSED,
1682 		  hb_buffer_t *buffer)
1683 {
1684   unsigned int count = buffer->len;
1685   if (unlikely (!count)) return;
1686 
1687   foreach_syllable (buffer, start, end)
1688     final_reordering_syllable (plan, buffer, start, end);
1689 
1690   HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
1691   HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
1692 }
1693 
1694 
1695 static void
clear_syllables(const hb_ot_shape_plan_t * plan HB_UNUSED,hb_font_t * font HB_UNUSED,hb_buffer_t * buffer)1696 clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
1697 		 hb_font_t *font HB_UNUSED,
1698 		 hb_buffer_t *buffer)
1699 {
1700   hb_glyph_info_t *info = buffer->info;
1701   unsigned int count = buffer->len;
1702   for (unsigned int i = 0; i < count; i++)
1703     info[i].syllable() = 0;
1704 }
1705 
1706 
1707 static bool
decompose_indic(const hb_ot_shape_normalize_context_t * c,hb_codepoint_t ab,hb_codepoint_t * a,hb_codepoint_t * b)1708 decompose_indic (const hb_ot_shape_normalize_context_t *c,
1709 		 hb_codepoint_t  ab,
1710 		 hb_codepoint_t *a,
1711 		 hb_codepoint_t *b)
1712 {
1713   switch (ab)
1714   {
1715     /* Don't decompose these. */
1716     case 0x0931u  : return false; /* DEVANAGARI LETTER RRA */
1717     case 0x0B94u  : return false; /* TAMIL LETTER AU */
1718 
1719 
1720     /*
1721      * Decompose split matras that don't have Unicode decompositions.
1722      */
1723 
1724     /* Khmer */
1725     case 0x17BEu  : *a = 0x17C1u; *b= 0x17BEu; return true;
1726     case 0x17BFu  : *a = 0x17C1u; *b= 0x17BFu; return true;
1727     case 0x17C0u  : *a = 0x17C1u; *b= 0x17C0u; return true;
1728     case 0x17C4u  : *a = 0x17C1u; *b= 0x17C4u; return true;
1729     case 0x17C5u  : *a = 0x17C1u; *b= 0x17C5u; return true;
1730 
1731 #if 0
1732     /* Gujarati */
1733     /* This one has no decomposition in Unicode, but needs no decomposition either. */
1734     /* case 0x0AC9u  : return false; */
1735 
1736     /* Oriya */
1737     case 0x0B57u  : *a = no decomp, -> RIGHT; return true;
1738 #endif
1739   }
1740 
1741   if ((ab == 0x0DDAu || hb_in_range (ab, 0x0DDCu, 0x0DDEu)))
1742   {
1743     /*
1744      * Sinhala split matras...  Let the fun begin.
1745      *
1746      * These four characters have Unicode decompositions.  However, Uniscribe
1747      * decomposes them "Khmer-style", that is, it uses the character itself to
1748      * get the second half.  The first half of all four decompositions is always
1749      * U+0DD9.
1750      *
1751      * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are
1752      * broken with Uniscribe.  But we need to support them.  As such, we only
1753      * do the Uniscribe-style decomposition if the character is transformed into
1754      * its "sec.half" form by the 'pstf' feature.  Otherwise, we fall back to
1755      * Unicode decomposition.
1756      *
1757      * Note that we can't unconditionally use Unicode decomposition.  That would
1758      * break some other fonts, that are designed to work with Uniscribe, and
1759      * don't have positioning features for the Unicode-style decomposition.
1760      *
1761      * Argh...
1762      *
1763      * The Uniscribe behavior is now documented in the newly published Sinhala
1764      * spec in 2012:
1765      *
1766      *   http://www.microsoft.com/typography/OpenTypeDev/sinhala/intro.htm#shaping
1767      */
1768 
1769     const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data;
1770 
1771     hb_codepoint_t glyph;
1772 
1773     if (hb_options ().uniscribe_bug_compatible ||
1774 	(c->font->get_nominal_glyph (ab, &glyph) &&
1775 	 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face)))
1776     {
1777       /* Ok, safe to use Uniscribe-style decomposition. */
1778       *a = 0x0DD9u;
1779       *b = ab;
1780       return true;
1781     }
1782   }
1783 
1784   return (bool) c->unicode->decompose (ab, a, b);
1785 }
1786 
1787 static bool
compose_indic(const hb_ot_shape_normalize_context_t * c,hb_codepoint_t a,hb_codepoint_t b,hb_codepoint_t * ab)1788 compose_indic (const hb_ot_shape_normalize_context_t *c,
1789 	       hb_codepoint_t  a,
1790 	       hb_codepoint_t  b,
1791 	       hb_codepoint_t *ab)
1792 {
1793   /* Avoid recomposing split matras. */
1794   if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
1795     return false;
1796 
1797   /* Composition-exclusion exceptions that we want to recompose. */
1798   if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; }
1799 
1800   return (bool) c->unicode->compose (a, b, ab);
1801 }
1802 
1803 
1804 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic =
1805 {
1806   "indic",
1807   collect_features_indic,
1808   override_features_indic,
1809   data_create_indic,
1810   data_destroy_indic,
1811   NULL, /* preprocess_text */
1812   NULL, /* postprocess_glyphs */
1813   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
1814   decompose_indic,
1815   compose_indic,
1816   setup_masks_indic,
1817   NULL, /* disable_otl */
1818   HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
1819   false, /* fallback_position */
1820 };
1821