hb-ot-layout.cc revision 49901862e36e1c153835877a9f1183729333bbbe
1/*
2 * Copyright © 1998-2004  David Turner and Werner Lemberg
3 * Copyright © 2006  Behdad Esfahbod
4 * Copyright © 2007,2008,2009  Red Hat, Inc.
5 * Copyright © 2012,2013  Google, Inc.
6 *
7 *  This is part of HarfBuzz, a text shaping library.
8 *
9 * Permission is hereby granted, without written agreement and without
10 * license or royalty fees, to use, copy, modify, and distribute this
11 * software and its documentation for any purpose, provided that the
12 * above copyright notice and the following two paragraphs appear in
13 * all copies of this software.
14 *
15 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
16 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
17 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
18 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
19 * DAMAGE.
20 *
21 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
22 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
23 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
24 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
25 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
26 *
27 * Red Hat Author(s): Behdad Esfahbod
28 * Google Author(s): Behdad Esfahbod
29 */
30
31#include "hb-ot-layout-private.hh"
32
33#include "hb-ot-layout-gdef-table.hh"
34#include "hb-ot-layout-gsub-table.hh"
35#include "hb-ot-layout-gpos-table.hh"
36#include "hb-ot-layout-jstf-table.hh"
37
38#include "hb-ot-map-private.hh"
39
40#include <stdlib.h>
41#include <string.h>
42
43
44HB_SHAPER_DATA_ENSURE_DECLARE(ot, face)
45
46hb_ot_layout_t *
47_hb_ot_layout_create (hb_face_t *face)
48{
49  hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
50  if (unlikely (!layout))
51    return NULL;
52
53  layout->gdef_blob = OT::Sanitizer<OT::GDEF>::sanitize (face->reference_table (HB_OT_TAG_GDEF));
54  layout->gdef = OT::Sanitizer<OT::GDEF>::lock_instance (layout->gdef_blob);
55
56  layout->gsub_blob = OT::Sanitizer<OT::GSUB>::sanitize (face->reference_table (HB_OT_TAG_GSUB));
57  layout->gsub = OT::Sanitizer<OT::GSUB>::lock_instance (layout->gsub_blob);
58
59  layout->gpos_blob = OT::Sanitizer<OT::GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
60  layout->gpos = OT::Sanitizer<OT::GPOS>::lock_instance (layout->gpos_blob);
61
62  layout->gsub_lookup_count = layout->gsub->get_lookup_count ();
63  layout->gpos_lookup_count = layout->gpos->get_lookup_count ();
64
65  layout->gsub_accels = (hb_ot_layout_lookup_accelerator_t *) calloc (layout->gsub->get_lookup_count (), sizeof (hb_ot_layout_lookup_accelerator_t));
66  layout->gpos_accels = (hb_ot_layout_lookup_accelerator_t *) calloc (layout->gpos->get_lookup_count (), sizeof (hb_ot_layout_lookup_accelerator_t));
67
68  if (unlikely ((layout->gsub_lookup_count && !layout->gsub_accels) ||
69		(layout->gpos_lookup_count && !layout->gpos_accels)))
70  {
71    _hb_ot_layout_destroy (layout);
72    return NULL;
73  }
74
75  for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
76    layout->gsub_accels[i].init (layout->gsub->get_lookup (i));
77  for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
78    layout->gpos_accels[i].init (layout->gpos->get_lookup (i));
79
80  return layout;
81}
82
83void
84_hb_ot_layout_destroy (hb_ot_layout_t *layout)
85{
86  for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
87    layout->gsub_accels[i].fini (layout->gsub->get_lookup (i));
88  for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
89    layout->gpos_accels[i].fini (layout->gpos->get_lookup (i));
90
91  free (layout->gsub_accels);
92  free (layout->gpos_accels);
93
94  hb_blob_destroy (layout->gdef_blob);
95  hb_blob_destroy (layout->gsub_blob);
96  hb_blob_destroy (layout->gpos_blob);
97
98  free (layout);
99}
100
101static inline const OT::GDEF&
102_get_gdef (hb_face_t *face)
103{
104  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GDEF);
105  return *hb_ot_layout_from_face (face)->gdef;
106}
107static inline const OT::GSUB&
108_get_gsub (hb_face_t *face)
109{
110  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GSUB);
111  return *hb_ot_layout_from_face (face)->gsub;
112}
113static inline const OT::GPOS&
114_get_gpos (hb_face_t *face)
115{
116  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GPOS);
117  return *hb_ot_layout_from_face (face)->gpos;
118}
119
120
121/*
122 * GDEF
123 */
124
125hb_bool_t
126hb_ot_layout_has_glyph_classes (hb_face_t *face)
127{
128  return _get_gdef (face).has_glyph_classes ();
129}
130
131hb_ot_layout_glyph_class_t
132hb_ot_layout_get_glyph_class (hb_face_t      *face,
133			      hb_codepoint_t  glyph)
134{
135  return (hb_ot_layout_glyph_class_t) _get_gdef (face).get_glyph_class (glyph);
136}
137
138void
139hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
140				  hb_ot_layout_glyph_class_t  klass,
141				  hb_set_t                   *glyphs /* OUT */)
142{
143  return _get_gdef (face).get_glyphs_in_class (klass, glyphs);
144}
145
146unsigned int
147hb_ot_layout_get_attach_points (hb_face_t      *face,
148				hb_codepoint_t  glyph,
149				unsigned int    start_offset,
150				unsigned int   *point_count /* IN/OUT */,
151				unsigned int   *point_array /* OUT */)
152{
153  return _get_gdef (face).get_attach_points (glyph, start_offset, point_count, point_array);
154}
155
156unsigned int
157hb_ot_layout_get_ligature_carets (hb_font_t      *font,
158				  hb_direction_t  direction,
159				  hb_codepoint_t  glyph,
160				  unsigned int    start_offset,
161				  unsigned int   *caret_count /* IN/OUT */,
162				  int            *caret_array /* OUT */)
163{
164  return _get_gdef (font->face).get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
165}
166
167
168/*
169 * GSUB/GPOS
170 */
171
172static const OT::GSUBGPOS&
173get_gsubgpos_table (hb_face_t *face,
174		    hb_tag_t   table_tag)
175{
176  switch (table_tag) {
177    case HB_OT_TAG_GSUB: return _get_gsub (face);
178    case HB_OT_TAG_GPOS: return _get_gpos (face);
179    default:             return OT::Null(OT::GSUBGPOS);
180  }
181}
182
183
184unsigned int
185hb_ot_layout_table_get_script_tags (hb_face_t    *face,
186				    hb_tag_t      table_tag,
187				    unsigned int  start_offset,
188				    unsigned int *script_count /* IN/OUT */,
189				    hb_tag_t     *script_tags /* OUT */)
190{
191  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
192
193  return g.get_script_tags (start_offset, script_count, script_tags);
194}
195
196#define HB_OT_TAG_LATIN_SCRIPT		HB_TAG ('l', 'a', 't', 'n')
197
198hb_bool_t
199hb_ot_layout_table_find_script (hb_face_t    *face,
200				hb_tag_t      table_tag,
201				hb_tag_t      script_tag,
202				unsigned int *script_index)
203{
204  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
205  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
206
207  if (g.find_script_index (script_tag, script_index))
208    return true;
209
210  /* try finding 'DFLT' */
211  if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index))
212    return false;
213
214  /* try with 'dflt'; MS site has had typos and many fonts use it now :(.
215   * including many versions of DejaVu Sans Mono! */
216  if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index))
217    return false;
218
219  /* try with 'latn'; some old fonts put their features there even though
220     they're really trying to support Thai, for example :( */
221  if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index))
222    return false;
223
224  if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
225  return false;
226}
227
228hb_bool_t
229hb_ot_layout_table_choose_script (hb_face_t      *face,
230				  hb_tag_t        table_tag,
231				  const hb_tag_t *script_tags,
232				  unsigned int   *script_index,
233				  hb_tag_t       *chosen_script)
234{
235  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
236  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
237
238  while (*script_tags)
239  {
240    if (g.find_script_index (*script_tags, script_index)) {
241      if (chosen_script)
242        *chosen_script = *script_tags;
243      return true;
244    }
245    script_tags++;
246  }
247
248  /* try finding 'DFLT' */
249  if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index)) {
250    if (chosen_script)
251      *chosen_script = HB_OT_TAG_DEFAULT_SCRIPT;
252    return false;
253  }
254
255  /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
256  if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index)) {
257    if (chosen_script)
258      *chosen_script = HB_OT_TAG_DEFAULT_LANGUAGE;
259    return false;
260  }
261
262  /* try with 'latn'; some old fonts put their features there even though
263     they're really trying to support Thai, for example :( */
264  if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index)) {
265    if (chosen_script)
266      *chosen_script = HB_OT_TAG_LATIN_SCRIPT;
267    return false;
268  }
269
270  if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
271  if (chosen_script)
272    *chosen_script = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
273  return false;
274}
275
276unsigned int
277hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
278				     hb_tag_t      table_tag,
279				     unsigned int  start_offset,
280				     unsigned int *feature_count /* IN/OUT */,
281				     hb_tag_t     *feature_tags /* OUT */)
282{
283  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
284
285  return g.get_feature_tags (start_offset, feature_count, feature_tags);
286}
287
288
289unsigned int
290hb_ot_layout_script_get_language_tags (hb_face_t    *face,
291				       hb_tag_t      table_tag,
292				       unsigned int  script_index,
293				       unsigned int  start_offset,
294				       unsigned int *language_count /* IN/OUT */,
295				       hb_tag_t     *language_tags /* OUT */)
296{
297  const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
298
299  return s.get_lang_sys_tags (start_offset, language_count, language_tags);
300}
301
302hb_bool_t
303hb_ot_layout_script_find_language (hb_face_t    *face,
304				   hb_tag_t      table_tag,
305				   unsigned int  script_index,
306				   hb_tag_t      language_tag,
307				   unsigned int *language_index)
308{
309  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
310  const OT::Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);
311
312  if (s.find_lang_sys_index (language_tag, language_index))
313    return true;
314
315  /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
316  if (s.find_lang_sys_index (HB_OT_TAG_DEFAULT_LANGUAGE, language_index))
317    return false;
318
319  if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
320  return false;
321}
322
323hb_bool_t
324hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
325						  hb_tag_t      table_tag,
326						  unsigned int  script_index,
327						  unsigned int  language_index,
328						  unsigned int *feature_index)
329{
330  const OT::LangSys &l = get_gsubgpos_table (face, table_tag).get_script (script_index).get_lang_sys (language_index);
331
332  if (feature_index) *feature_index = l.get_required_feature_index ();
333
334  return l.has_required_feature ();
335}
336
337unsigned int
338hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
339					   hb_tag_t      table_tag,
340					   unsigned int  script_index,
341					   unsigned int  language_index,
342					   unsigned int  start_offset,
343					   unsigned int *feature_count /* IN/OUT */,
344					   unsigned int *feature_indexes /* OUT */)
345{
346  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
347  const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
348
349  return l.get_feature_indexes (start_offset, feature_count, feature_indexes);
350}
351
352unsigned int
353hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
354					hb_tag_t      table_tag,
355					unsigned int  script_index,
356					unsigned int  language_index,
357					unsigned int  start_offset,
358					unsigned int *feature_count /* IN/OUT */,
359					hb_tag_t     *feature_tags /* OUT */)
360{
361  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
362  const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
363
364  ASSERT_STATIC (sizeof (unsigned int) == sizeof (hb_tag_t));
365  unsigned int ret = l.get_feature_indexes (start_offset, feature_count, (unsigned int *) feature_tags);
366
367  if (feature_tags) {
368    unsigned int count = *feature_count;
369    for (unsigned int i = 0; i < count; i++)
370      feature_tags[i] = g.get_feature_tag ((unsigned int) feature_tags[i]);
371  }
372
373  return ret;
374}
375
376
377hb_bool_t
378hb_ot_layout_language_find_feature (hb_face_t    *face,
379				    hb_tag_t      table_tag,
380				    unsigned int  script_index,
381				    unsigned int  language_index,
382				    hb_tag_t      feature_tag,
383				    unsigned int *feature_index)
384{
385  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
386  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
387  const OT::LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
388
389  unsigned int num_features = l.get_feature_count ();
390  for (unsigned int i = 0; i < num_features; i++) {
391    unsigned int f_index = l.get_feature_index (i);
392
393    if (feature_tag == g.get_feature_tag (f_index)) {
394      if (feature_index) *feature_index = f_index;
395      return true;
396    }
397  }
398
399  if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
400  return false;
401}
402
403unsigned int
404hb_ot_layout_feature_get_lookups (hb_face_t    *face,
405				  hb_tag_t      table_tag,
406				  unsigned int  feature_index,
407				  unsigned int  start_offset,
408				  unsigned int *lookup_count /* IN/OUT */,
409				  unsigned int *lookup_indexes /* OUT */)
410{
411  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
412  const OT::Feature &f = g.get_feature (feature_index);
413
414  return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
415}
416
417unsigned int
418hb_ot_layout_table_get_lookup_count (hb_face_t    *face,
419				     hb_tag_t      table_tag)
420{
421  switch (table_tag)
422  {
423    case HB_OT_TAG_GSUB:
424    {
425      return hb_ot_layout_from_face (face)->gsub_lookup_count;
426    }
427    case HB_OT_TAG_GPOS:
428    {
429      return hb_ot_layout_from_face (face)->gpos_lookup_count;
430    }
431  }
432  return 0;
433}
434
435static void
436_hb_ot_layout_collect_lookups_lookups (hb_face_t      *face,
437				       hb_tag_t        table_tag,
438				       unsigned int    feature_index,
439				       hb_set_t       *lookup_indexes /* OUT */)
440{
441  unsigned int lookup_indices[32];
442  unsigned int offset, len;
443
444  offset = 0;
445  do {
446    len = ARRAY_LENGTH (lookup_indices);
447    hb_ot_layout_feature_get_lookups (face,
448				      table_tag,
449				      feature_index,
450				      offset, &len,
451				      lookup_indices);
452
453    for (unsigned int i = 0; i < len; i++)
454      lookup_indexes->add (lookup_indices[i]);
455
456    offset += len;
457  } while (len == ARRAY_LENGTH (lookup_indices));
458}
459
460static void
461_hb_ot_layout_collect_lookups_features (hb_face_t      *face,
462					hb_tag_t        table_tag,
463					unsigned int    script_index,
464					unsigned int    language_index,
465					const hb_tag_t *features,
466					hb_set_t       *lookup_indexes /* OUT */)
467{
468  if (!features)
469  {
470    unsigned int required_feature_index;
471    if (hb_ot_layout_language_get_required_feature_index (face,
472							  table_tag,
473							  script_index,
474							  language_index,
475							  &required_feature_index))
476      _hb_ot_layout_collect_lookups_lookups (face,
477					     table_tag,
478					     required_feature_index,
479					     lookup_indexes);
480
481    /* All features */
482    unsigned int feature_indices[32];
483    unsigned int offset, len;
484
485    offset = 0;
486    do {
487      len = ARRAY_LENGTH (feature_indices);
488      hb_ot_layout_language_get_feature_indexes (face,
489						 table_tag,
490						 script_index,
491						 language_index,
492						 offset, &len,
493						 feature_indices);
494
495      for (unsigned int i = 0; i < len; i++)
496	_hb_ot_layout_collect_lookups_lookups (face,
497					       table_tag,
498					       feature_indices[i],
499					       lookup_indexes);
500
501      offset += len;
502    } while (len == ARRAY_LENGTH (feature_indices));
503  }
504  else
505  {
506    for (; *features; features++)
507    {
508      unsigned int feature_index;
509      if (hb_ot_layout_language_find_feature (face,
510					      table_tag,
511					      script_index,
512					      language_index,
513					      *features,
514					      &feature_index))
515        _hb_ot_layout_collect_lookups_lookups (face,
516					       table_tag,
517					       feature_index,
518					       lookup_indexes);
519    }
520  }
521}
522
523static void
524_hb_ot_layout_collect_lookups_languages (hb_face_t      *face,
525					 hb_tag_t        table_tag,
526					 unsigned int    script_index,
527					 const hb_tag_t *languages,
528					 const hb_tag_t *features,
529					 hb_set_t       *lookup_indexes /* OUT */)
530{
531  _hb_ot_layout_collect_lookups_features (face,
532					  table_tag,
533					  script_index,
534					  HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
535					  features,
536					  lookup_indexes);
537
538  if (!languages)
539  {
540    /* All languages */
541    unsigned int count = hb_ot_layout_script_get_language_tags (face,
542								table_tag,
543								script_index,
544								0, NULL, NULL);
545    for (unsigned int language_index = 0; language_index < count; language_index++)
546      _hb_ot_layout_collect_lookups_features (face,
547					      table_tag,
548					      script_index,
549					      language_index,
550					      features,
551					      lookup_indexes);
552  }
553  else
554  {
555    for (; *languages; languages++)
556    {
557      unsigned int language_index;
558      if (hb_ot_layout_script_find_language (face,
559					     table_tag,
560					     script_index,
561					     *languages,
562					     &language_index))
563        _hb_ot_layout_collect_lookups_features (face,
564						table_tag,
565						script_index,
566						language_index,
567						features,
568						lookup_indexes);
569    }
570  }
571}
572
573void
574hb_ot_layout_collect_lookups (hb_face_t      *face,
575			      hb_tag_t        table_tag,
576			      const hb_tag_t *scripts,
577			      const hb_tag_t *languages,
578			      const hb_tag_t *features,
579			      hb_set_t       *lookup_indexes /* OUT */)
580{
581  if (!scripts)
582  {
583    /* All scripts */
584    unsigned int count = hb_ot_layout_table_get_script_tags (face,
585							     table_tag,
586							     0, NULL, NULL);
587    for (unsigned int script_index = 0; script_index < count; script_index++)
588      _hb_ot_layout_collect_lookups_languages (face,
589					       table_tag,
590					       script_index,
591					       languages,
592					       features,
593					       lookup_indexes);
594  }
595  else
596  {
597    for (; *scripts; scripts++)
598    {
599      unsigned int script_index;
600      if (hb_ot_layout_table_find_script (face,
601					  table_tag,
602					  *scripts,
603					  &script_index))
604        _hb_ot_layout_collect_lookups_languages (face,
605						 table_tag,
606						 script_index,
607						 languages,
608						 features,
609						 lookup_indexes);
610    }
611  }
612}
613
614void
615hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
616				    hb_tag_t      table_tag,
617				    unsigned int  lookup_index,
618				    hb_set_t     *glyphs_before, /* OUT. May be NULL */
619				    hb_set_t     *glyphs_input,  /* OUT. May be NULL */
620				    hb_set_t     *glyphs_after,  /* OUT. May be NULL */
621				    hb_set_t     *glyphs_output  /* OUT. May be NULL */)
622{
623  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return;
624
625  OT::hb_collect_glyphs_context_t c (face,
626				     glyphs_before,
627				     glyphs_input,
628				     glyphs_after,
629				     glyphs_output);
630
631  switch (table_tag)
632  {
633    case HB_OT_TAG_GSUB:
634    {
635      const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
636      l.collect_glyphs (&c);
637      return;
638    }
639    case HB_OT_TAG_GPOS:
640    {
641      const OT::PosLookup& l = hb_ot_layout_from_face (face)->gpos->get_lookup (lookup_index);
642      l.collect_glyphs (&c);
643      return;
644    }
645  }
646}
647
648
649/*
650 * OT::GSUB
651 */
652
653hb_bool_t
654hb_ot_layout_has_substitution (hb_face_t *face)
655{
656  return &_get_gsub (face) != &OT::Null(OT::GSUB);
657}
658
659hb_bool_t
660hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
661				      unsigned int          lookup_index,
662				      const hb_codepoint_t *glyphs,
663				      unsigned int          glyphs_length,
664				      hb_bool_t             zero_context)
665{
666  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
667  return hb_ot_layout_lookup_would_substitute_fast (face, lookup_index, glyphs, glyphs_length, zero_context);
668}
669
670hb_bool_t
671hb_ot_layout_lookup_would_substitute_fast (hb_face_t            *face,
672					   unsigned int          lookup_index,
673					   const hb_codepoint_t *glyphs,
674					   unsigned int          glyphs_length,
675					   hb_bool_t             zero_context)
676{
677  if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
678  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context);
679
680  const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
681
682  return l.would_apply (&c, &hb_ot_layout_from_face (face)->gsub_accels[lookup_index].digest);
683}
684
685void
686hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
687{
688  OT::GSUB::substitute_start (font, buffer);
689}
690
691void
692hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
693{
694  OT::GSUB::substitute_finish (font, buffer);
695}
696
697void
698hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
699				        unsigned int  lookup_index,
700				        hb_set_t     *glyphs)
701{
702  OT::hb_closure_context_t c (face, glyphs);
703
704  const OT::SubstLookup& l = _get_gsub (face).get_lookup (lookup_index);
705
706  l.closure (&c);
707}
708
709/*
710 * OT::GPOS
711 */
712
713hb_bool_t
714hb_ot_layout_has_positioning (hb_face_t *face)
715{
716  return &_get_gpos (face) != &OT::Null(OT::GPOS);
717}
718
719void
720hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
721{
722  OT::GPOS::position_start (font, buffer);
723}
724
725void
726hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer)
727{
728  OT::GPOS::position_finish (font, buffer);
729}
730
731hb_bool_t
732hb_ot_layout_get_size_params (hb_face_t    *face,
733			      unsigned int *design_size,       /* OUT.  May be NULL */
734			      unsigned int *subfamily_id,      /* OUT.  May be NULL */
735			      unsigned int *subfamily_name_id, /* OUT.  May be NULL */
736			      unsigned int *range_start,       /* OUT.  May be NULL */
737			      unsigned int *range_end          /* OUT.  May be NULL */)
738{
739  const OT::GPOS &gpos = _get_gpos (face);
740  const hb_tag_t tag = HB_TAG ('s','i','z','e');
741
742  unsigned int num_features = gpos.get_feature_count ();
743  for (unsigned int i = 0; i < num_features; i++)
744  {
745    if (tag == gpos.get_feature_tag (i))
746    {
747      const OT::Feature &f = gpos.get_feature (i);
748      const OT::FeatureParamsSize &params = f.get_feature_params ().get_size_params (tag);
749
750      if (params.designSize)
751      {
752#define PARAM(a, A) if (a) *a = params.A
753	PARAM (design_size, designSize);
754	PARAM (subfamily_id, subfamilyID);
755	PARAM (subfamily_name_id, subfamilyNameID);
756	PARAM (range_start, rangeStart);
757	PARAM (range_end, rangeEnd);
758#undef PARAM
759
760	return true;
761      }
762    }
763  }
764
765#define PARAM(a, A) if (a) *a = 0
766  PARAM (design_size, designSize);
767  PARAM (subfamily_id, subfamilyID);
768  PARAM (subfamily_name_id, subfamilyNameID);
769  PARAM (range_start, rangeStart);
770  PARAM (range_end, rangeEnd);
771#undef PARAM
772
773  return false;
774}
775
776
777/*
778 * Parts of different types are implemented here such that they have direct
779 * access to GSUB/GPOS lookups.
780 */
781
782
783struct GSUBProxy
784{
785  static const unsigned int table_index = 0;
786  typedef OT::SubstLookup Lookup;
787
788  GSUBProxy (hb_face_t *face) :
789    table (*hb_ot_layout_from_face (face)->gsub),
790    accels (hb_ot_layout_from_face (face)->gsub_accels) {}
791
792  const OT::GSUB &table;
793  const hb_ot_layout_lookup_accelerator_t *accels;
794};
795
796struct GPOSProxy
797{
798  static const unsigned int table_index = 1;
799  typedef OT::PosLookup Lookup;
800
801  GPOSProxy (hb_face_t *face) :
802    table (*hb_ot_layout_from_face (face)->gpos),
803    accels (hb_ot_layout_from_face (face)->gpos_accels) {}
804
805  const OT::GPOS &table;
806  const hb_ot_layout_lookup_accelerator_t *accels;
807};
808
809
810template <typename Lookup>
811static inline bool apply_once (OT::hb_apply_context_t *c,
812			       const Lookup &lookup)
813{
814  if (!c->check_glyph_property (&c->buffer->cur(), c->lookup_props))
815    return false;
816  return lookup.dispatch (c);
817}
818
819template <typename Proxy>
820static inline bool
821apply_string (OT::hb_apply_context_t *c,
822	      const typename Proxy::Lookup &lookup,
823	      const hb_ot_layout_lookup_accelerator_t &accel)
824{
825  bool ret = false;
826  OT::hb_is_inplace_context_t inplace_c (c->face);
827  bool inplace = lookup.is_inplace (&inplace_c);
828
829  if (unlikely (!c->buffer->len || !c->lookup_mask))
830    return false;
831
832  c->set_lookup (lookup);
833
834  if (likely (!lookup.is_reverse ()))
835  {
836    /* in/out forward substitution/positioning */
837    if (Proxy::table_index == 0)
838      c->buffer->clear_output ();
839    c->buffer->idx = 0;
840
841    while (c->buffer->idx < c->buffer->len)
842    {
843      if (accel.digest.may_have (c->buffer->cur().codepoint) &&
844	  (c->buffer->cur().mask & c->lookup_mask) &&
845	  apply_once (c, lookup))
846	ret = true;
847      else
848	c->buffer->next_glyph ();
849    }
850    if (ret)
851    {
852      if (!inplace)
853	c->buffer->swap_buffers ();
854      else
855        assert (!c->buffer->has_separate_output ());
856    }
857  }
858  else
859  {
860    /* in-place backward substitution/positioning */
861    if (Proxy::table_index == 0)
862      c->buffer->remove_output ();
863    c->buffer->idx = c->buffer->len - 1;
864    do
865    {
866      if (accel.digest.may_have (c->buffer->cur().codepoint) &&
867	  (c->buffer->cur().mask & c->lookup_mask) &&
868	  apply_once (c, lookup))
869	ret = true;
870      /* The reverse lookup doesn't "advance" cursor (for good reason). */
871      c->buffer->idx--;
872
873    }
874    while ((int) c->buffer->idx >= 0);
875  }
876
877  return ret;
878}
879
880template <typename Proxy>
881inline void hb_ot_map_t::apply (const Proxy &proxy,
882				const hb_ot_shape_plan_t *plan,
883				hb_font_t *font,
884				hb_buffer_t *buffer) const
885{
886  const unsigned int table_index = proxy.table_index;
887  unsigned int i = 0;
888  OT::hb_apply_context_t c (table_index, font, buffer);
889  c.set_recurse_func (Proxy::Lookup::apply_recurse_func);
890
891  for (unsigned int stage_index = 0; stage_index < stages[table_index].len; stage_index++) {
892    const stage_map_t *stage = &stages[table_index][stage_index];
893    for (; i < stage->last_lookup; i++)
894    {
895      unsigned int lookup_index = lookups[table_index][i].index;
896      c.set_lookup_mask (lookups[table_index][i].mask);
897      c.set_auto_zwj (lookups[table_index][i].auto_zwj);
898      apply_string<Proxy> (&c,
899			   proxy.table.get_lookup (lookup_index),
900			   proxy.accels[lookup_index]);
901    }
902
903    if (stage->pause_func)
904    {
905      buffer->clear_output ();
906      stage->pause_func (plan, font, buffer);
907    }
908  }
909}
910
911void hb_ot_map_t::substitute (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
912{
913  GSUBProxy proxy (font->face);
914  apply (proxy, plan, font, buffer);
915}
916
917void hb_ot_map_t::position (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
918{
919  GPOSProxy proxy (font->face);
920  apply (proxy, plan, font, buffer);
921}
922
923HB_INTERNAL void
924hb_ot_layout_substitute_lookup (OT::hb_apply_context_t *c,
925				const OT::SubstLookup &lookup,
926				const hb_ot_layout_lookup_accelerator_t &accel)
927{
928  apply_string<GSUBProxy> (c, lookup, accel);
929}
930