hb-ot-layout.cc revision 27674b4bb351e501373bd9994e4ba6546e465cf7
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}
433
434static void
435_hb_ot_layout_collect_lookups_lookups (hb_face_t      *face,
436				       hb_tag_t        table_tag,
437				       unsigned int    feature_index,
438				       hb_set_t       *lookup_indexes /* OUT */)
439{
440  unsigned int lookup_indices[32];
441  unsigned int offset, len;
442
443  offset = 0;
444  do {
445    len = ARRAY_LENGTH (lookup_indices);
446    hb_ot_layout_feature_get_lookups (face,
447				      table_tag,
448				      feature_index,
449				      offset, &len,
450				      lookup_indices);
451
452    for (unsigned int i = 0; i < len; i++)
453      lookup_indexes->add (lookup_indices[i]);
454
455    offset += len;
456  } while (len == ARRAY_LENGTH (lookup_indices));
457}
458
459static void
460_hb_ot_layout_collect_lookups_features (hb_face_t      *face,
461					hb_tag_t        table_tag,
462					unsigned int    script_index,
463					unsigned int    language_index,
464					const hb_tag_t *features,
465					hb_set_t       *lookup_indexes /* OUT */)
466{
467  if (!features)
468  {
469    unsigned int required_feature_index;
470    if (hb_ot_layout_language_get_required_feature_index (face,
471							  table_tag,
472							  script_index,
473							  language_index,
474							  &required_feature_index))
475      _hb_ot_layout_collect_lookups_lookups (face,
476					     table_tag,
477					     required_feature_index,
478					     lookup_indexes);
479
480    /* All features */
481    unsigned int feature_indices[32];
482    unsigned int offset, len;
483
484    offset = 0;
485    do {
486      len = ARRAY_LENGTH (feature_indices);
487      hb_ot_layout_language_get_feature_indexes (face,
488						 table_tag,
489						 script_index,
490						 language_index,
491						 offset, &len,
492						 feature_indices);
493
494      for (unsigned int i = 0; i < len; i++)
495	_hb_ot_layout_collect_lookups_lookups (face,
496					       table_tag,
497					       feature_indices[i],
498					       lookup_indexes);
499
500      offset += len;
501    } while (len == ARRAY_LENGTH (feature_indices));
502  }
503  else
504  {
505    for (; *features; features++)
506    {
507      unsigned int feature_index;
508      if (hb_ot_layout_language_find_feature (face,
509					      table_tag,
510					      script_index,
511					      language_index,
512					      *features,
513					      &feature_index))
514        _hb_ot_layout_collect_lookups_lookups (face,
515					       table_tag,
516					       feature_index,
517					       lookup_indexes);
518    }
519  }
520}
521
522static void
523_hb_ot_layout_collect_lookups_languages (hb_face_t      *face,
524					 hb_tag_t        table_tag,
525					 unsigned int    script_index,
526					 const hb_tag_t *languages,
527					 const hb_tag_t *features,
528					 hb_set_t       *lookup_indexes /* OUT */)
529{
530  _hb_ot_layout_collect_lookups_features (face,
531					  table_tag,
532					  script_index,
533					  HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX,
534					  features,
535					  lookup_indexes);
536
537  if (!languages)
538  {
539    /* All languages */
540    unsigned int count = hb_ot_layout_script_get_language_tags (face,
541								table_tag,
542								script_index,
543								0, NULL, NULL);
544    for (unsigned int language_index = 0; language_index < count; language_index++)
545      _hb_ot_layout_collect_lookups_features (face,
546					      table_tag,
547					      script_index,
548					      language_index,
549					      features,
550					      lookup_indexes);
551  }
552  else
553  {
554    for (; *languages; languages++)
555    {
556      unsigned int language_index;
557      if (hb_ot_layout_script_find_language (face,
558					     table_tag,
559					     script_index,
560					     *languages,
561					     &language_index))
562        _hb_ot_layout_collect_lookups_features (face,
563						table_tag,
564						script_index,
565						language_index,
566						features,
567						lookup_indexes);
568    }
569  }
570}
571
572void
573hb_ot_layout_collect_lookups (hb_face_t      *face,
574			      hb_tag_t        table_tag,
575			      const hb_tag_t *scripts,
576			      const hb_tag_t *languages,
577			      const hb_tag_t *features,
578			      hb_set_t       *lookup_indexes /* OUT */)
579{
580  if (!scripts)
581  {
582    /* All scripts */
583    unsigned int count = hb_ot_layout_table_get_script_tags (face,
584							     table_tag,
585							     0, NULL, NULL);
586    for (unsigned int script_index = 0; script_index < count; script_index++)
587      _hb_ot_layout_collect_lookups_languages (face,
588					       table_tag,
589					       script_index,
590					       languages,
591					       features,
592					       lookup_indexes);
593  }
594  else
595  {
596    for (; *scripts; scripts++)
597    {
598      unsigned int script_index;
599      if (hb_ot_layout_table_find_script (face,
600					  table_tag,
601					  *scripts,
602					  &script_index))
603        _hb_ot_layout_collect_lookups_languages (face,
604						 table_tag,
605						 script_index,
606						 languages,
607						 features,
608						 lookup_indexes);
609    }
610  }
611}
612
613void
614hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
615				    hb_tag_t      table_tag,
616				    unsigned int  lookup_index,
617				    hb_set_t     *glyphs_before, /* OUT. May be NULL */
618				    hb_set_t     *glyphs_input,  /* OUT. May be NULL */
619				    hb_set_t     *glyphs_after,  /* OUT. May be NULL */
620				    hb_set_t     *glyphs_output  /* OUT. May be NULL */)
621{
622  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return;
623
624  OT::hb_collect_glyphs_context_t c (face,
625				     glyphs_before,
626				     glyphs_input,
627				     glyphs_after,
628				     glyphs_output);
629
630  switch (table_tag)
631  {
632    case HB_OT_TAG_GSUB:
633    {
634      const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
635      l.collect_glyphs (&c);
636      return;
637    }
638    case HB_OT_TAG_GPOS:
639    {
640      const OT::PosLookup& l = hb_ot_layout_from_face (face)->gpos->get_lookup (lookup_index);
641      l.collect_glyphs (&c);
642      return;
643    }
644  }
645}
646
647
648/*
649 * OT::GSUB
650 */
651
652hb_bool_t
653hb_ot_layout_has_substitution (hb_face_t *face)
654{
655  return &_get_gsub (face) != &OT::Null(OT::GSUB);
656}
657
658hb_bool_t
659hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
660				      unsigned int          lookup_index,
661				      const hb_codepoint_t *glyphs,
662				      unsigned int          glyphs_length,
663				      hb_bool_t             zero_context)
664{
665  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
666  return hb_ot_layout_lookup_would_substitute_fast (face, lookup_index, glyphs, glyphs_length, zero_context);
667}
668
669hb_bool_t
670hb_ot_layout_lookup_would_substitute_fast (hb_face_t            *face,
671					   unsigned int          lookup_index,
672					   const hb_codepoint_t *glyphs,
673					   unsigned int          glyphs_length,
674					   hb_bool_t             zero_context)
675{
676  if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
677  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context);
678
679  const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
680
681  return l.would_apply (&c, &hb_ot_layout_from_face (face)->gsub_accels[lookup_index].digest);
682}
683
684void
685hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
686{
687  OT::GSUB::substitute_start (font, buffer);
688}
689
690void
691hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
692{
693  OT::GSUB::substitute_finish (font, buffer);
694}
695
696void
697hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
698				        unsigned int  lookup_index,
699				        hb_set_t     *glyphs)
700{
701  OT::hb_closure_context_t c (face, glyphs);
702
703  const OT::SubstLookup& l = _get_gsub (face).get_lookup (lookup_index);
704
705  l.closure (&c);
706}
707
708/*
709 * OT::GPOS
710 */
711
712hb_bool_t
713hb_ot_layout_has_positioning (hb_face_t *face)
714{
715  return &_get_gpos (face) != &OT::Null(OT::GPOS);
716}
717
718void
719hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
720{
721  OT::GPOS::position_start (font, buffer);
722}
723
724void
725hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer)
726{
727  OT::GPOS::position_finish (font, buffer);
728}
729
730hb_bool_t
731hb_ot_layout_get_size_params (hb_face_t    *face,
732			      unsigned int *design_size,       /* OUT.  May be NULL */
733			      unsigned int *subfamily_id,      /* OUT.  May be NULL */
734			      unsigned int *subfamily_name_id, /* OUT.  May be NULL */
735			      unsigned int *range_start,       /* OUT.  May be NULL */
736			      unsigned int *range_end          /* OUT.  May be NULL */)
737{
738  const OT::GPOS &gpos = _get_gpos (face);
739  const hb_tag_t tag = HB_TAG ('s','i','z','e');
740
741  unsigned int num_features = gpos.get_feature_count ();
742  for (unsigned int i = 0; i < num_features; i++)
743  {
744    if (tag == gpos.get_feature_tag (i))
745    {
746      const OT::Feature &f = gpos.get_feature (i);
747      const OT::FeatureParamsSize &params = f.get_feature_params ().get_size_params (tag);
748
749      if (params.designSize)
750      {
751#define PARAM(a, A) if (a) *a = params.A
752	PARAM (design_size, designSize);
753	PARAM (subfamily_id, subfamilyID);
754	PARAM (subfamily_name_id, subfamilyNameID);
755	PARAM (range_start, rangeStart);
756	PARAM (range_end, rangeEnd);
757#undef PARAM
758
759	return true;
760      }
761    }
762  }
763
764#define PARAM(a, A) if (a) *a = 0
765  PARAM (design_size, designSize);
766  PARAM (subfamily_id, subfamilyID);
767  PARAM (subfamily_name_id, subfamilyNameID);
768  PARAM (range_start, rangeStart);
769  PARAM (range_end, rangeEnd);
770#undef PARAM
771
772  return false;
773}
774
775
776/*
777 * Parts of different types are implemented here such that they have direct
778 * access to GSUB/GPOS lookups.
779 */
780
781
782struct GSUBProxy
783{
784  static const unsigned int table_index = 0;
785  typedef OT::SubstLookup Lookup;
786
787  GSUBProxy (hb_face_t *face) :
788    table (*hb_ot_layout_from_face (face)->gsub),
789    accels (hb_ot_layout_from_face (face)->gsub_accels) {}
790
791  const OT::GSUB &table;
792  const hb_ot_layout_lookup_accelerator_t *accels;
793};
794
795struct GPOSProxy
796{
797  static const unsigned int table_index = 1;
798  typedef OT::PosLookup Lookup;
799
800  GPOSProxy (hb_face_t *face) :
801    table (*hb_ot_layout_from_face (face)->gpos),
802    accels (hb_ot_layout_from_face (face)->gpos_accels) {}
803
804  const OT::GPOS &table;
805  const hb_ot_layout_lookup_accelerator_t *accels;
806};
807
808
809template <typename Lookup>
810static inline bool apply_once (OT::hb_apply_context_t *c,
811			       const Lookup &lookup)
812{
813  if (!c->check_glyph_property (&c->buffer->cur(), c->lookup_props))
814    return false;
815  return lookup.dispatch (c);
816}
817
818template <typename Proxy>
819static inline bool
820apply_string (OT::hb_apply_context_t *c,
821	      const typename Proxy::Lookup &lookup,
822	      const hb_ot_layout_lookup_accelerator_t &accel)
823{
824  bool ret = false;
825  OT::hb_is_inplace_context_t inplace_c (c->face);
826  bool inplace = lookup.is_inplace (&inplace_c);
827
828  if (unlikely (!c->buffer->len || !c->lookup_mask))
829    return false;
830
831  c->set_lookup (lookup);
832
833  if (likely (!lookup.is_reverse ()))
834  {
835    /* in/out forward substitution/positioning */
836    if (Proxy::table_index == 0)
837      c->buffer->clear_output ();
838    c->buffer->idx = 0;
839
840    while (c->buffer->idx < c->buffer->len)
841    {
842      if (accel.digest.may_have (c->buffer->cur().codepoint) &&
843	  (c->buffer->cur().mask & c->lookup_mask) &&
844	  apply_once (c, lookup))
845	ret = true;
846      else
847	c->buffer->next_glyph ();
848    }
849    if (ret)
850    {
851      if (!inplace)
852	c->buffer->swap_buffers ();
853      else
854        assert (!c->buffer->has_separate_output ());
855    }
856  }
857  else
858  {
859    /* in-place backward substitution/positioning */
860    if (Proxy::table_index == 0)
861      c->buffer->remove_output ();
862    c->buffer->idx = c->buffer->len - 1;
863    do
864    {
865      if (accel.digest.may_have (c->buffer->cur().codepoint) &&
866	  (c->buffer->cur().mask & c->lookup_mask) &&
867	  apply_once (c, lookup))
868	ret = true;
869      else
870	c->buffer->idx--;
871
872    }
873    while ((int) c->buffer->idx >= 0);
874  }
875
876  return ret;
877}
878
879template <typename Proxy>
880inline void hb_ot_map_t::apply (const Proxy &proxy,
881				const hb_ot_shape_plan_t *plan,
882				hb_font_t *font,
883				hb_buffer_t *buffer) const
884{
885  const unsigned int table_index = proxy.table_index;
886  unsigned int i = 0;
887  OT::hb_apply_context_t c (table_index, font, buffer);
888  c.set_recurse_func (Proxy::Lookup::apply_recurse_func);
889
890  for (unsigned int stage_index = 0; stage_index < stages[table_index].len; stage_index++) {
891    const stage_map_t *stage = &stages[table_index][stage_index];
892    for (; i < stage->last_lookup; i++)
893    {
894      unsigned int lookup_index = lookups[table_index][i].index;
895      c.set_lookup_mask (lookups[table_index][i].mask);
896      c.set_auto_zwj (lookups[table_index][i].auto_zwj);
897      apply_string<Proxy> (&c,
898			   proxy.table.get_lookup (lookup_index),
899			   proxy.accels[lookup_index]);
900    }
901
902    if (stage->pause_func)
903    {
904      buffer->clear_output ();
905      stage->pause_func (plan, font, buffer);
906    }
907  }
908}
909
910void hb_ot_map_t::substitute (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
911{
912  GSUBProxy proxy (font->face);
913  apply (proxy, plan, font, buffer);
914}
915
916void hb_ot_map_t::position (const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer) const
917{
918  GPOSProxy proxy (font->face);
919  apply (proxy, plan, font, buffer);
920}
921
922HB_INTERNAL void
923hb_ot_layout_substitute_lookup (OT::hb_apply_context_t *c,
924				const OT::SubstLookup &lookup,
925				const hb_ot_layout_lookup_accelerator_t &accel)
926{
927  apply_string<GSUBProxy> (c, lookup, accel);
928}
929