hb-ot-shape.cc revision 0594a2448440208efa0acac9a5d8d52d43108289 
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#include "hb-ot-shape-private.hh"
30#include "hb-ot-shape-normalize-private.hh"
31
32#include "hb-font-private.hh"
33#include "hb-set-private.hh"
34
35
36
37hb_tag_t common_features[] = {
38  HB_TAG('c','c','m','p'),
39  HB_TAG('l','i','g','a'),
40  HB_TAG('l','o','c','l'),
41  HB_TAG('m','a','r','k'),
42  HB_TAG('m','k','m','k'),
43  HB_TAG('r','l','i','g'),
44};
45
46
47hb_tag_t horizontal_features[] = {
48  HB_TAG('c','a','l','t'),
49  HB_TAG('c','l','i','g'),
50  HB_TAG('c','u','r','s'),
51  HB_TAG('k','e','r','n'),
52};
53
54/* Note:
55 * Technically speaking, vrt2 and vert are mutually exclusive.
56 * According to the spec, valt and vpal are also mutually exclusive.
57 * But we apply them all for now.
58 */
59hb_tag_t vertical_features[] = {
60  HB_TAG('v','a','l','t'),
61  HB_TAG('v','e','r','t'),
62  HB_TAG('v','k','r','n'),
63  HB_TAG('v','p','a','l'),
64  HB_TAG('v','r','t','2'),
65};
66
67
68
69struct hb_ot_shape_planner_t
70{
71  hb_ot_map_builder_t map;
72  hb_ot_complex_shaper_t shaper;
73
74  hb_ot_shape_planner_t (void) : map () {}
75  ~hb_ot_shape_planner_t (void) { map.finish (); }
76
77  inline void compile (hb_face_t *face,
78		       const hb_segment_properties_t *props,
79		       struct hb_ot_shape_plan_t &plan)
80  {
81    plan.shaper = shaper;
82    map.compile (face, props, plan.map);
83  }
84
85  private:
86  NO_COPY (hb_ot_shape_planner_t);
87};
88
89static void
90hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
91			      const hb_segment_properties_t  *props,
92			      const hb_feature_t             *user_features,
93			      unsigned int                    num_user_features)
94{
95  switch (props->direction) {
96    case HB_DIRECTION_LTR:
97      planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
98      planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
99      break;
100    case HB_DIRECTION_RTL:
101      planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
102      planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
103      break;
104    case HB_DIRECTION_TTB:
105    case HB_DIRECTION_BTT:
106    case HB_DIRECTION_INVALID:
107    default:
108      break;
109  }
110
111#define ADD_FEATURES(array) \
112  HB_STMT_START { \
113    for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
114      planner->map.add_bool_feature (array[i]); \
115  } HB_STMT_END
116
117  hb_ot_shape_complex_collect_features (planner->shaper, &planner->map, props);
118
119  ADD_FEATURES (common_features);
120
121  if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
122    ADD_FEATURES (horizontal_features);
123  else
124    ADD_FEATURES (vertical_features);
125
126#undef ADD_FEATURES
127
128  for (unsigned int i = 0; i < num_user_features; i++) {
129    const hb_feature_t *feature = &user_features[i];
130    planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
131  }
132}
133
134
135struct hb_ot_shape_context_t
136{
137  /* Input to hb_ot_shape_execute() */
138  hb_ot_shape_plan_t *plan;
139  hb_font_t *font;
140  hb_face_t *face;
141  hb_buffer_t  *buffer;
142  const hb_feature_t *user_features;
143  unsigned int        num_user_features;
144
145  /* Transient stuff */
146  hb_direction_t target_direction;
147  hb_bool_t applied_position_complex;
148};
149
150static void
151hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
152{
153  hb_mask_t global_mask = c->plan->map.get_global_mask ();
154  c->buffer->reset_masks (global_mask);
155
156  hb_ot_shape_complex_setup_masks (c->plan->shaper, &c->plan->map, c->buffer, c->font);
157
158  for (unsigned int i = 0; i < c->num_user_features; i++)
159  {
160    const hb_feature_t *feature = &c->user_features[i];
161    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
162      unsigned int shift;
163      hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
164      c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
165    }
166  }
167}
168
169
170/* Main shaper */
171
172/* Prepare */
173
174static void
175hb_set_unicode_props (hb_buffer_t *buffer)
176{
177  unsigned int count = buffer->len;
178  for (unsigned int i = 0; i < count; i++)
179    _hb_glyph_info_set_unicode_props (&buffer->info[i], buffer->unicode);
180}
181
182static void
183hb_form_clusters (hb_buffer_t *buffer)
184{
185  unsigned int count = buffer->len;
186  for (unsigned int i = 1; i < count; i++)
187    if (FLAG (_hb_glyph_info_get_general_category (&buffer->info[i])) &
188	(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
189	 FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
190	 FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
191      buffer->info[i].cluster = buffer->info[i - 1].cluster; /* XXX do the min() here */
192}
193
194static void
195hb_ensure_native_direction (hb_buffer_t *buffer)
196{
197  hb_direction_t direction = buffer->props.direction;
198
199  /* TODO vertical:
200   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
201   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
202   * first. */
203  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||
204      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
205  {
206    hb_buffer_reverse_clusters (buffer);
207    buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);
208  }
209}
210
211
212/* Substitute */
213
214static void
215hb_mirror_chars (hb_ot_shape_context_t *c)
216{
217  hb_unicode_funcs_t *unicode = c->buffer->unicode;
218
219  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
220    return;
221
222  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
223
224  unsigned int count = c->buffer->len;
225  for (unsigned int i = 0; i < count; i++) {
226    hb_codepoint_t codepoint = hb_unicode_mirroring (unicode, c->buffer->info[i].codepoint);
227    if (likely (codepoint == c->buffer->info[i].codepoint))
228      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
229    else
230      c->buffer->info[i].codepoint = codepoint;
231  }
232}
233
234static void
235hb_map_glyphs (hb_font_t    *font,
236	       hb_buffer_t  *buffer)
237{
238  hb_codepoint_t glyph;
239
240  if (unlikely (!buffer->len))
241    return;
242
243  buffer->clear_output ();
244
245  unsigned int count = buffer->len - 1;
246  for (buffer->idx = 0; buffer->idx < count;) {
247    if (unlikely (_hb_unicode_is_variation_selector (buffer->cur(+1).codepoint))) {
248      hb_font_get_glyph (font, buffer->cur().codepoint, buffer->cur(+1).codepoint, &glyph);
249      buffer->replace_glyphs (2, 1, &glyph);
250    } else {
251      hb_font_get_glyph (font, buffer->cur().codepoint, 0, &glyph);
252      buffer->replace_glyph (glyph);
253    }
254  }
255  if (likely (buffer->idx < buffer->len)) {
256    hb_font_get_glyph (font, buffer->cur().codepoint, 0, &glyph);
257    buffer->replace_glyph (glyph);
258  }
259  buffer->swap_buffers ();
260}
261
262static void
263hb_substitute_default (hb_ot_shape_context_t *c)
264{
265  hb_ot_layout_substitute_start (c->buffer);
266
267  hb_mirror_chars (c);
268
269  hb_map_glyphs (c->font, c->buffer);
270}
271
272static void
273hb_ot_substitute_complex (hb_ot_shape_context_t *c)
274{
275  if (hb_ot_layout_has_substitution (c->face)) {
276    c->plan->map.substitute (c->face, c->buffer);
277  }
278
279  hb_ot_layout_substitute_finish (c->buffer);
280
281  return;
282}
283
284
285/* Position */
286
287static void
288hb_position_default (hb_ot_shape_context_t *c)
289{
290  hb_ot_layout_position_start (c->buffer);
291
292  unsigned int count = c->buffer->len;
293  for (unsigned int i = 0; i < count; i++) {
294    hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
295					     c->buffer->props.direction,
296					     &c->buffer->pos[i].x_advance,
297					     &c->buffer->pos[i].y_advance);
298    hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
299						 c->buffer->props.direction,
300						 &c->buffer->pos[i].x_offset,
301						 &c->buffer->pos[i].y_offset);
302  }
303}
304
305static void
306hb_ot_position_complex (hb_ot_shape_context_t *c)
307{
308
309  if (hb_ot_layout_has_positioning (c->face))
310  {
311    /* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
312
313    unsigned int count = c->buffer->len;
314    for (unsigned int i = 0; i < count; i++) {
315      hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
316					      HB_DIRECTION_LTR,
317					      &c->buffer->pos[i].x_offset,
318					      &c->buffer->pos[i].y_offset);
319    }
320
321    c->plan->map.position (c->font, c->buffer);
322
323    for (unsigned int i = 0; i < count; i++) {
324      hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
325						   HB_DIRECTION_LTR,
326						   &c->buffer->pos[i].x_offset,
327						   &c->buffer->pos[i].y_offset);
328    }
329
330    c->applied_position_complex = true;
331  }
332
333  hb_ot_layout_position_finish (c->buffer);
334
335  return;
336}
337
338static void
339hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
340{
341  /* TODO Mark pos */
342}
343
344static void
345hb_truetype_kern (hb_ot_shape_context_t *c)
346{
347  /* TODO Check for kern=0 */
348  unsigned int count = c->buffer->len;
349  for (unsigned int i = 1; i < count; i++) {
350    hb_position_t x_kern, y_kern, kern1, kern2;
351    hb_font_get_glyph_kerning_for_direction (c->font,
352					     c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
353					     c->buffer->props.direction,
354					     &x_kern, &y_kern);
355
356    kern1 = x_kern >> 1;
357    kern2 = x_kern - kern1;
358    c->buffer->pos[i - 1].x_advance += kern1;
359    c->buffer->pos[i].x_advance += kern2;
360    c->buffer->pos[i].x_offset += kern2;
361
362    kern1 = y_kern >> 1;
363    kern2 = y_kern - kern1;
364    c->buffer->pos[i - 1].y_advance += kern1;
365    c->buffer->pos[i].y_advance += kern2;
366    c->buffer->pos[i].y_offset += kern2;
367  }
368}
369
370static void
371hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
372{
373  hb_truetype_kern (c);
374}
375
376static void
377hb_hide_zerowidth (hb_ot_shape_context_t *c)
378{
379  /* TODO Save the space character in the font? */
380  hb_codepoint_t space;
381  if (!hb_font_get_glyph (c->font, ' ', 0, &space))
382    return; /* No point! */
383
384  unsigned int count = c->buffer->len;
385  for (unsigned int i = 0; i < count; i++)
386    if (unlikely (_hb_glyph_info_is_zero_width (&c->buffer->info[i]))) {
387      c->buffer->info[i].codepoint = space;
388      c->buffer->pos[i].x_advance = 0;
389      c->buffer->pos[i].y_advance = 0;
390    }
391}
392
393
394/* Do it! */
395
396static void
397hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
398{
399  c->buffer->deallocate_var_all ();
400
401  /* Save the original direction, we use it later. */
402  c->target_direction = c->buffer->props.direction;
403
404  HB_BUFFER_ALLOCATE_VAR (c->buffer, unicode_props0);
405  HB_BUFFER_ALLOCATE_VAR (c->buffer, unicode_props1);
406
407  hb_set_unicode_props (c->buffer);
408
409  hb_form_clusters (c->buffer);
410
411  hb_ensure_native_direction (c->buffer);
412
413  _hb_ot_shape_normalize (c->font, c->buffer, hb_ot_shape_complex_normalization_preference (c->plan->shaper));
414
415  hb_ot_shape_setup_masks (c);
416
417  /* SUBSTITUTE */
418  {
419    hb_substitute_default (c);
420
421    hb_ot_substitute_complex (c);
422  }
423
424  /* POSITION */
425  {
426    hb_position_default (c);
427
428    hb_ot_position_complex (c);
429
430    hb_bool_t position_fallback = !c->applied_position_complex;
431    if (position_fallback)
432      hb_position_complex_fallback (c);
433
434    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
435      hb_buffer_reverse (c->buffer);
436
437    if (position_fallback)
438      hb_position_complex_fallback_visual (c);
439  }
440
441  hb_hide_zerowidth (c);
442
443  HB_BUFFER_DEALLOCATE_VAR (c->buffer, unicode_props1);
444  HB_BUFFER_DEALLOCATE_VAR (c->buffer, unicode_props0);
445
446  c->buffer->props.direction = c->target_direction;
447
448  c->buffer->deallocate_var_all ();
449}
450
451static void
452hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
453			   hb_face_t                *face,
454			   const hb_segment_properties_t  *props,
455			   const hb_feature_t       *user_features,
456			   unsigned int              num_user_features)
457{
458  hb_ot_shape_planner_t planner;
459
460  assert (HB_DIRECTION_IS_VALID (props->direction));
461
462  planner.shaper = hb_ot_shape_complex_categorize (props);
463
464  hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
465
466  planner.compile (face, props, *plan);
467}
468
469static void
470hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
471		     hb_font_t          *font,
472		     hb_buffer_t        *buffer,
473		     const hb_feature_t *user_features,
474		     unsigned int        num_user_features)
475{
476  hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
477  hb_ot_shape_execute_internal (&c);
478}
479
480hb_bool_t
481_hb_ot_shape (hb_font_t          *font,
482	      hb_buffer_t        *buffer,
483	      const hb_feature_t *features,
484	      unsigned int        num_features)
485{
486  hb_ot_shape_plan_t plan;
487
488  buffer->guess_properties ();
489
490  hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
491  hb_ot_shape_execute (&plan, font, buffer, features, num_features);
492
493  return true;
494}
495
496
497void
498hb_ot_shape_glyphs_closure (hb_font_t          *font,
499			    hb_buffer_t        *buffer,
500			    const hb_feature_t *features,
501			    unsigned int        num_features,
502			    hb_set_t           *glyphs)
503{
504  hb_ot_shape_plan_t plan;
505
506  buffer->guess_properties ();
507
508  hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
509
510  /* TODO: normalization? have shapers do closure()? */
511  /* TODO: Deal with mirrored chars? */
512  hb_map_glyphs (font, buffer);
513
514  /* Seed it.  It's user's responsibility to have cleard glyphs
515   * if that's what they desire. */
516  unsigned int count = buffer->len;
517  for (unsigned int i = 0; i < count; i++)
518    hb_set_add (glyphs, buffer->info[i].codepoint);
519
520  /* And find transitive closure. */
521  hb_set_t copy;
522  copy.init ();
523
524  do {
525    copy.set (glyphs);
526    plan.map.substitute_closure (font->face, glyphs);
527  } while (!copy.equal (glyphs));
528}
529