hb-ot-shape.cc revision 16c6a27b4bffc19026944c7bea9cf0a3a8ff1d8f 
1/*
2 * Copyright © 2009,2010  Red Hat, Inc.
3 * Copyright © 2010,2011  Google, Inc.
4 *
5 *  This is part of HarfBuzz, a text shaping library.
6 *
7 * Permission is hereby granted, without written agreement and without
8 * license or royalty fees, to use, copy, modify, and distribute this
9 * software and its documentation for any purpose, provided that the
10 * above copyright notice and the following two paragraphs appear in
11 * all copies of this software.
12 *
13 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
14 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
15 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
16 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
17 * DAMAGE.
18 *
19 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
20 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
22 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
23 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
24 *
25 * Red Hat Author(s): Behdad Esfahbod
26 * Google Author(s): Behdad Esfahbod
27 */
28
29#define HB_SHAPER ot
30#define hb_ot_shaper_face_data_t hb_ot_layout_t
31#define hb_ot_shaper_shape_plan_data_t hb_ot_shape_plan_t
32#include "hb-shaper-impl-private.hh"
33
34#include "hb-ot-shape-private.hh"
35#include "hb-ot-shape-normalize-private.hh"
36#include "hb-ot-shape-complex-private.hh"
37
38#include "hb-ot-layout-private.hh"
39#include "hb-set-private.hh"
40
41
42hb_tag_t common_features[] = {
43  HB_TAG('c','c','m','p'),
44  HB_TAG('l','i','g','a'),
45  HB_TAG('l','o','c','l'),
46  HB_TAG('m','a','r','k'),
47  HB_TAG('m','k','m','k'),
48  HB_TAG('r','l','i','g'),
49};
50
51
52hb_tag_t horizontal_features[] = {
53  HB_TAG('c','a','l','t'),
54  HB_TAG('c','l','i','g'),
55  HB_TAG('c','u','r','s'),
56  HB_TAG('k','e','r','n'),
57};
58
59/* Note:
60 * Technically speaking, vrt2 and vert are mutually exclusive.
61 * According to the spec, valt and vpal are also mutually exclusive.
62 * But we apply them all for now.
63 */
64hb_tag_t vertical_features[] = {
65  HB_TAG('v','a','l','t'),
66  HB_TAG('v','e','r','t'),
67  HB_TAG('v','k','r','n'),
68  HB_TAG('v','p','a','l'),
69  HB_TAG('v','r','t','2'),
70};
71
72
73
74static void
75hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
76			      const hb_segment_properties_t  *props,
77			      const hb_feature_t             *user_features,
78			      unsigned int                    num_user_features)
79{
80  switch (props->direction) {
81    case HB_DIRECTION_LTR:
82      planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
83      planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
84      break;
85    case HB_DIRECTION_RTL:
86      planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
87      planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
88      break;
89    case HB_DIRECTION_TTB:
90    case HB_DIRECTION_BTT:
91    case HB_DIRECTION_INVALID:
92    default:
93      break;
94  }
95
96#define ADD_FEATURES(array) \
97  HB_STMT_START { \
98    for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
99      planner->map.add_bool_feature (array[i]); \
100  } HB_STMT_END
101
102  if (planner->shaper->collect_features)
103    planner->shaper->collect_features (planner);
104
105  ADD_FEATURES (common_features);
106
107  if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
108    ADD_FEATURES (horizontal_features);
109  else
110    ADD_FEATURES (vertical_features);
111
112  if (planner->shaper->override_features)
113    planner->shaper->override_features (planner);
114
115#undef ADD_FEATURES
116
117  for (unsigned int i = 0; i < num_user_features; i++) {
118    const hb_feature_t *feature = &user_features[i];
119    planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
120  }
121}
122
123
124/*
125 * shaper face data
126 */
127
128hb_ot_shaper_face_data_t *
129_hb_ot_shaper_face_data_create (hb_face_t *face)
130{
131  return _hb_ot_layout_create (face);
132}
133
134void
135_hb_ot_shaper_face_data_destroy (hb_ot_shaper_face_data_t *data)
136{
137  _hb_ot_layout_destroy (data);
138}
139
140
141/*
142 * shaper font data
143 */
144
145struct hb_ot_shaper_font_data_t {};
146
147hb_ot_shaper_font_data_t *
148_hb_ot_shaper_font_data_create (hb_font_t *font)
149{
150  return (hb_ot_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED;
151}
152
153void
154_hb_ot_shaper_font_data_destroy (hb_ot_shaper_font_data_t *data)
155{
156}
157
158
159/*
160 * shaper shape_plan data
161 */
162
163hb_ot_shaper_shape_plan_data_t *
164_hb_ot_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan,
165				      const hb_feature_t *user_features,
166				      unsigned int        num_user_features)
167{
168  hb_ot_shape_plan_t *data = (hb_ot_shape_plan_t *) calloc (1, sizeof (hb_ot_shape_plan_t));
169  if (unlikely (!data))
170    return NULL;
171
172  hb_ot_shape_planner_t planner (shape_plan);
173
174  planner.shaper = hb_ot_shape_complex_categorize (&shape_plan->props);
175
176  hb_ot_shape_collect_features (&planner, &shape_plan->props, user_features, num_user_features);
177
178  planner.compile (*data);
179
180  return data;
181}
182
183void
184_hb_ot_shaper_shape_plan_data_destroy (hb_ot_shaper_shape_plan_data_t *data)
185{
186  data->map.finish ();
187
188  free (data);
189}
190
191
192/*
193 * shaper
194 */
195
196struct hb_ot_shape_context_t
197{
198  /* Input to hb_ot_shape_internal() */
199  hb_ot_shape_plan_t *plan;
200  hb_font_t *font;
201  hb_face_t *face;
202  hb_buffer_t  *buffer;
203  const hb_feature_t *user_features;
204  unsigned int        num_user_features;
205
206  /* Transient stuff */
207  hb_direction_t target_direction;
208  hb_bool_t applied_position_complex;
209};
210
211static void
212hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
213{
214  hb_mask_t global_mask = c->plan->map.get_global_mask ();
215  c->buffer->reset_masks (global_mask);
216
217  if (c->plan->shaper->setup_masks)
218    c->plan->shaper->setup_masks (c->plan, c->buffer, c->font);
219
220  for (unsigned int i = 0; i < c->num_user_features; i++)
221  {
222    const hb_feature_t *feature = &c->user_features[i];
223    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
224      unsigned int shift;
225      hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
226      c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
227    }
228  }
229}
230
231
232/* Main shaper */
233
234/* Prepare */
235
236static void
237hb_set_unicode_props (hb_buffer_t *buffer)
238{
239  unsigned int count = buffer->len;
240  for (unsigned int i = 0; i < count; i++)
241    _hb_glyph_info_set_unicode_props (&buffer->info[i], buffer->unicode);
242}
243
244static void
245hb_form_clusters (hb_buffer_t *buffer)
246{
247  unsigned int count = buffer->len;
248  for (unsigned int i = 1; i < count; i++)
249    if (FLAG (_hb_glyph_info_get_general_category (&buffer->info[i])) &
250	(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
251	 FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
252	 FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
253      buffer->merge_clusters (i - 1, i + 1);
254}
255
256static void
257hb_ensure_native_direction (hb_buffer_t *buffer)
258{
259  hb_direction_t direction = buffer->props.direction;
260
261  /* TODO vertical:
262   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
263   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
264   * first. */
265  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||
266      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
267  {
268    hb_buffer_reverse_clusters (buffer);
269    buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);
270  }
271}
272
273
274/* Substitute */
275
276static void
277hb_mirror_chars (hb_ot_shape_context_t *c)
278{
279  hb_unicode_funcs_t *unicode = c->buffer->unicode;
280
281  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
282    return;
283
284  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
285
286  unsigned int count = c->buffer->len;
287  for (unsigned int i = 0; i < count; i++) {
288    hb_codepoint_t codepoint = unicode->mirroring (c->buffer->info[i].codepoint);
289    if (likely (codepoint == c->buffer->info[i].codepoint))
290      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
291    else
292      c->buffer->info[i].codepoint = codepoint;
293  }
294}
295
296static void
297hb_map_glyphs (hb_font_t    *font,
298	       hb_buffer_t  *buffer)
299{
300  hb_codepoint_t glyph;
301
302  if (unlikely (!buffer->len))
303    return;
304
305  buffer->clear_output ();
306
307  unsigned int count = buffer->len - 1;
308  for (buffer->idx = 0; buffer->idx < count;) {
309    if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) {
310      font->get_glyph (buffer->cur().codepoint, buffer->cur(+1).codepoint, &glyph);
311      buffer->replace_glyphs (2, 1, &glyph);
312    } else {
313      font->get_glyph (buffer->cur().codepoint, 0, &glyph);
314      buffer->replace_glyph (glyph);
315    }
316  }
317  if (likely (buffer->idx < buffer->len)) {
318    font->get_glyph (buffer->cur().codepoint, 0, &glyph);
319    buffer->replace_glyph (glyph);
320  }
321  buffer->swap_buffers ();
322}
323
324static void
325hb_substitute_default (hb_ot_shape_context_t *c)
326{
327  hb_mirror_chars (c);
328
329  hb_map_glyphs (c->font, c->buffer);
330}
331
332static void
333hb_synthesize_glyph_classes (hb_ot_shape_context_t *c)
334{
335  unsigned int count = c->buffer->len;
336  for (unsigned int i = 0; i < count; i++)
337    c->buffer->info[i].glyph_props() = FLAG (_hb_glyph_info_get_general_category (&c->buffer->info[i])) &
338				       (FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
339					FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
340					FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)) ?
341				       HB_OT_LAYOUT_GLYPH_CLASS_MARK :
342				       HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH;
343}
344
345
346static void
347hb_ot_substitute_complex (hb_ot_shape_context_t *c)
348{
349  hb_ot_layout_substitute_start (c->font, c->buffer);
350
351  if (!hb_ot_layout_has_glyph_classes (c->face))
352    hb_synthesize_glyph_classes (c);
353
354  if (hb_ot_layout_has_substitution (c->face))
355    c->plan->map.substitute (c->font, c->buffer);
356
357  hb_ot_layout_substitute_finish (c->font, c->buffer);
358
359  return;
360}
361
362
363/* Position */
364
365static void
366hb_position_default (hb_ot_shape_context_t *c)
367{
368  hb_ot_layout_position_start (c->font, c->buffer);
369
370  unsigned int count = c->buffer->len;
371  for (unsigned int i = 0; i < count; i++) {
372    c->font->get_glyph_advance_for_direction (c->buffer->info[i].codepoint,
373					      c->buffer->props.direction,
374					      &c->buffer->pos[i].x_advance,
375					      &c->buffer->pos[i].y_advance);
376    c->font->subtract_glyph_origin_for_direction (c->buffer->info[i].codepoint,
377						  c->buffer->props.direction,
378						  &c->buffer->pos[i].x_offset,
379						  &c->buffer->pos[i].y_offset);
380  }
381}
382
383static void
384hb_zero_mark_advances (hb_ot_shape_context_t *c)
385{
386  unsigned int count = c->buffer->len;
387  for (unsigned int i = 0; i < count; i++)
388    if (c->buffer->info[i].glyph_props() & HB_OT_LAYOUT_GLYPH_CLASS_MARK)
389    {
390      c->buffer->pos[i].x_advance = 0;
391      c->buffer->pos[i].y_advance = 0;
392    }
393}
394
395static void
396hb_ot_position_complex (hb_ot_shape_context_t *c)
397{
398
399  if (hb_ot_layout_has_positioning (c->face))
400  {
401    /* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
402
403    unsigned int count = c->buffer->len;
404    for (unsigned int i = 0; i < count; i++) {
405      c->font->add_glyph_origin_for_direction (c->buffer->info[i].codepoint,
406					       HB_DIRECTION_LTR,
407					       &c->buffer->pos[i].x_offset,
408					       &c->buffer->pos[i].y_offset);
409    }
410
411    c->plan->map.position (c->font, c->buffer);
412
413    for (unsigned int i = 0; i < count; i++) {
414      c->font->subtract_glyph_origin_for_direction (c->buffer->info[i].codepoint,
415						    HB_DIRECTION_LTR,
416						    &c->buffer->pos[i].x_offset,
417						    &c->buffer->pos[i].y_offset);
418    }
419
420    c->applied_position_complex = true;
421  } else
422    hb_zero_mark_advances (c);
423
424  hb_ot_layout_position_finish (c->font, c->buffer, c->plan->shaper->zero_width_attached_marks);
425
426  return;
427}
428
429static void
430hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
431{
432  /* TODO Mark pos */
433}
434
435static void
436hb_truetype_kern (hb_ot_shape_context_t *c)
437{
438  /* TODO Check for kern=0 */
439  unsigned int count = c->buffer->len;
440  for (unsigned int i = 1; i < count; i++) {
441    hb_position_t x_kern, y_kern, kern1, kern2;
442    c->font->get_glyph_kerning_for_direction (c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
443					      c->buffer->props.direction,
444					      &x_kern, &y_kern);
445
446    kern1 = x_kern >> 1;
447    kern2 = x_kern - kern1;
448    c->buffer->pos[i - 1].x_advance += kern1;
449    c->buffer->pos[i].x_advance += kern2;
450    c->buffer->pos[i].x_offset += kern2;
451
452    kern1 = y_kern >> 1;
453    kern2 = y_kern - kern1;
454    c->buffer->pos[i - 1].y_advance += kern1;
455    c->buffer->pos[i].y_advance += kern2;
456    c->buffer->pos[i].y_offset += kern2;
457  }
458}
459
460static void
461hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
462{
463  hb_truetype_kern (c);
464}
465
466static void
467hb_hide_zerowidth (hb_ot_shape_context_t *c)
468{
469  hb_codepoint_t space;
470  if (!c->font->get_glyph (' ', 0, &space))
471    return; /* No point! */
472
473  unsigned int count = c->buffer->len;
474  for (unsigned int i = 0; i < count; i++)
475    if (unlikely (!is_a_ligature (c->buffer->info[i]) &&
476		  _hb_glyph_info_is_zero_width (&c->buffer->info[i]))) {
477      c->buffer->info[i].codepoint = space;
478      c->buffer->pos[i].x_advance = 0;
479      c->buffer->pos[i].y_advance = 0;
480    }
481}
482
483
484/* Do it! */
485
486static void
487hb_ot_shape_internal (hb_ot_shape_context_t *c)
488{
489  c->buffer->deallocate_var_all ();
490
491  /* Save the original direction, we use it later. */
492  c->target_direction = c->buffer->props.direction;
493
494  HB_BUFFER_ALLOCATE_VAR (c->buffer, unicode_props0);
495  HB_BUFFER_ALLOCATE_VAR (c->buffer, unicode_props1);
496
497  c->buffer->clear_output ();
498
499  hb_set_unicode_props (c->buffer);
500
501  hb_form_clusters (c->buffer);
502
503  hb_ensure_native_direction (c->buffer);
504
505  _hb_ot_shape_normalize (c->font, c->buffer,
506			  c->plan->shaper->normalization_preference ?
507			  c->plan->shaper->normalization_preference (c->plan) :
508			  HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT);
509
510  hb_ot_shape_setup_masks (c);
511
512  /* SUBSTITUTE */
513  {
514    hb_substitute_default (c);
515
516    hb_ot_substitute_complex (c);
517  }
518
519  /* POSITION */
520  {
521    hb_position_default (c);
522
523    hb_ot_position_complex (c);
524
525    hb_bool_t position_fallback = !c->applied_position_complex;
526    if (position_fallback)
527      hb_position_complex_fallback (c);
528
529    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
530      hb_buffer_reverse (c->buffer);
531
532    if (position_fallback)
533      hb_position_complex_fallback_visual (c);
534  }
535
536  hb_hide_zerowidth (c);
537
538  HB_BUFFER_DEALLOCATE_VAR (c->buffer, unicode_props1);
539  HB_BUFFER_DEALLOCATE_VAR (c->buffer, unicode_props0);
540
541  c->buffer->props.direction = c->target_direction;
542
543  c->buffer->deallocate_var_all ();
544}
545
546
547hb_bool_t
548_hb_ot_shape (hb_shape_plan_t    *shape_plan,
549	      hb_font_t          *font,
550	      hb_buffer_t        *buffer,
551	      const hb_feature_t *features,
552	      unsigned int        num_features)
553{
554  hb_ot_shape_context_t c = {HB_SHAPER_DATA_GET (shape_plan), font, font->face, buffer, features, num_features};
555  hb_ot_shape_internal (&c);
556
557  return true;
558}
559
560
561void
562hb_ot_shape_glyphs_closure (hb_font_t          *font,
563			    hb_buffer_t        *buffer,
564			    const hb_feature_t *features,
565			    unsigned int        num_features,
566			    hb_set_t           *glyphs)
567{
568  hb_ot_shape_plan_t plan;
569
570  buffer->guess_properties ();
571
572  /* TODO cache / ensure correct backend, etc. */
573  hb_shape_plan_t *shape_plan = hb_shape_plan_create (font->face, &buffer->props, features, num_features, NULL);
574
575  /* TODO: normalization? have shapers do closure()? */
576  /* TODO: Deal with mirrored chars? */
577  hb_map_glyphs (font, buffer);
578
579  /* Seed it.  It's user's responsibility to have cleard glyphs
580   * if that's what they desire. */
581  unsigned int count = buffer->len;
582  for (unsigned int i = 0; i < count; i++)
583    hb_set_add (glyphs, buffer->info[i].codepoint);
584
585  /* And find transitive closure. */
586  hb_set_t copy;
587  copy.init ();
588
589  do {
590    copy.set (glyphs);
591    HB_SHAPER_DATA_GET (shape_plan)->map.substitute_closure (font->face, glyphs);
592  } while (!copy.equal (glyphs));
593
594  hb_shape_plan_destroy (shape_plan);
595}
596