hb-ot-shape.cc revision a4385f0b0a6949e2ce49e6a147ad4beaa724f6c3 
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
34
35
36hb_tag_t common_features[] = {
37  HB_TAG('c','c','m','p'),
38  HB_TAG('l','i','g','a'),
39  HB_TAG('l','o','c','l'),
40  HB_TAG('m','a','r','k'),
41  HB_TAG('m','k','m','k'),
42  HB_TAG('r','l','i','g'),
43};
44
45hb_tag_t horizontal_features[] = {
46  HB_TAG('c','a','l','t'),
47  HB_TAG('c','l','i','g'),
48  HB_TAG('c','u','r','s'),
49  HB_TAG('k','e','r','n'),
50};
51
52/* Note:
53 * Technically speaking, vrt2 and vert are mutually exclusive.
54 * According to the spec, valt and vpal are also mutually exclusive.
55 * But we apply them all for now.
56 */
57hb_tag_t vertical_features[] = {
58  HB_TAG('v','a','l','t'),
59  HB_TAG('v','e','r','t'),
60  HB_TAG('v','k','r','n'),
61  HB_TAG('v','p','a','l'),
62  HB_TAG('v','r','t','2'),
63};
64
65
66
67struct hb_ot_shape_planner_t
68{
69  hb_ot_map_builder_t map;
70  hb_ot_complex_shaper_t shaper;
71
72  hb_ot_shape_planner_t (void) : map () {}
73  ~hb_ot_shape_planner_t (void) { map.finish (); }
74
75  inline void compile (hb_face_t *face,
76		       const hb_segment_properties_t *props,
77		       struct hb_ot_shape_plan_t &plan)
78  {
79    plan.shaper = shaper;
80    map.compile (face, props, plan.map);
81  }
82
83  private:
84  NO_COPY (hb_ot_shape_planner_t);
85};
86
87static void
88hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
89			      const hb_segment_properties_t  *props,
90			      const hb_feature_t             *user_features,
91			      unsigned int                    num_user_features)
92{
93  switch (props->direction) {
94    case HB_DIRECTION_LTR:
95      planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
96      planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
97      break;
98    case HB_DIRECTION_RTL:
99      planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
100      planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
101      break;
102    case HB_DIRECTION_TTB:
103    case HB_DIRECTION_BTT:
104    case HB_DIRECTION_INVALID:
105    default:
106      break;
107  }
108
109#define ADD_FEATURES(array) \
110  HB_STMT_START { \
111    for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
112      planner->map.add_bool_feature (array[i]); \
113  } HB_STMT_END
114
115  hb_ot_shape_complex_collect_features (planner->shaper, &planner->map, props);
116
117  ADD_FEATURES (common_features);
118
119  if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
120    ADD_FEATURES (horizontal_features);
121  else
122    ADD_FEATURES (vertical_features);
123
124#undef ADD_FEATURES
125
126  for (unsigned int i = 0; i < num_user_features; i++) {
127    const hb_feature_t *feature = &user_features[i];
128    planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
129  }
130}
131
132
133struct hb_ot_shape_context_t
134{
135  /* Input to hb_ot_shape_execute() */
136  hb_ot_shape_plan_t *plan;
137  hb_font_t *font;
138  hb_face_t *face;
139  hb_buffer_t  *buffer;
140  const hb_feature_t *user_features;
141  unsigned int        num_user_features;
142
143  /* Transient stuff */
144  hb_direction_t target_direction;
145  hb_bool_t applied_position_complex;
146};
147
148static void
149hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
150{
151  hb_mask_t global_mask = c->plan->map.get_global_mask ();
152  c->buffer->reset_masks (global_mask);
153
154  hb_ot_shape_complex_setup_masks (c->plan->shaper, &c->plan->map, c->buffer, c->font);
155
156  for (unsigned int i = 0; i < c->num_user_features; i++)
157  {
158    const hb_feature_t *feature = &c->user_features[i];
159    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
160      unsigned int shift;
161      hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
162      c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
163    }
164  }
165}
166
167
168/* Main shaper */
169
170/* Prepare */
171
172static inline void
173set_unicode_props (hb_glyph_info_t *info, hb_unicode_funcs_t *unicode)
174{
175  info->general_category() = hb_unicode_general_category (unicode, info->codepoint);
176  info->combining_class() = _hb_unicode_modified_combining_class (unicode, info->codepoint);
177}
178
179static void
180hb_set_unicode_props (hb_buffer_t *buffer)
181{
182  unsigned int count = buffer->len;
183  for (unsigned int i = 0; i < count; i++)
184    set_unicode_props (&buffer->info[i], buffer->unicode);
185}
186
187static void
188hb_form_clusters (hb_buffer_t *buffer)
189{
190  unsigned int count = buffer->len;
191  for (unsigned int i = 1; i < count; i++)
192    if (FLAG (buffer->info[i].general_category()) &
193	(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
194	 FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
195	 FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
196      buffer->info[i].cluster = buffer->info[i - 1].cluster; /* XXX do the min() here */
197}
198
199static void
200hb_ensure_native_direction (hb_buffer_t *buffer)
201{
202  hb_direction_t direction = buffer->props.direction;
203
204  /* TODO vertical:
205   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
206   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
207   * first. */
208  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||
209      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
210  {
211    hb_buffer_reverse_clusters (buffer);
212    buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);
213  }
214}
215
216
217/* Substitute */
218
219static void
220hb_mirror_chars (hb_ot_shape_context_t *c)
221{
222  hb_unicode_funcs_t *unicode = c->buffer->unicode;
223
224  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
225    return;
226
227  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
228
229  unsigned int count = c->buffer->len;
230  for (unsigned int i = 0; i < count; i++) {
231    hb_codepoint_t codepoint = hb_unicode_mirroring (unicode, c->buffer->info[i].codepoint);
232    if (likely (codepoint == c->buffer->info[i].codepoint))
233      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
234    else
235      c->buffer->info[i].codepoint = codepoint;
236  }
237}
238
239static void
240hb_map_glyphs (hb_font_t    *font,
241	       hb_buffer_t  *buffer)
242{
243  hb_codepoint_t glyph;
244
245  if (unlikely (!buffer->len))
246    return;
247
248  buffer->clear_output ();
249
250  unsigned int count = buffer->len - 1;
251  for (buffer->idx = 0; buffer->idx < count;) {
252    if (unlikely (_hb_unicode_is_variation_selector (buffer->info[buffer->idx + 1].codepoint))) {
253      hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, buffer->info[buffer->idx + 1].codepoint, &glyph);
254      buffer->replace_glyphs (2, 1, &glyph);
255    } else {
256      hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, 0, &glyph);
257      buffer->replace_glyph (glyph);
258    }
259  }
260  if (likely (buffer->idx < buffer->len)) {
261    hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, 0, &glyph);
262    buffer->replace_glyph (glyph);
263  }
264  buffer->swap_buffers ();
265}
266
267static void
268hb_substitute_default (hb_ot_shape_context_t *c)
269{
270  hb_ot_layout_substitute_start (c->buffer);
271
272  hb_mirror_chars (c);
273
274  hb_map_glyphs (c->font, c->buffer);
275}
276
277static void
278hb_ot_substitute_complex (hb_ot_shape_context_t *c)
279{
280  if (hb_ot_layout_has_substitution (c->face)) {
281    c->plan->map.substitute (c->face, c->buffer);
282  }
283
284  hb_ot_layout_substitute_finish (c->buffer);
285
286  return;
287}
288
289
290/* Position */
291
292static void
293hb_position_default (hb_ot_shape_context_t *c)
294{
295  hb_ot_layout_position_start (c->buffer);
296
297  unsigned int count = c->buffer->len;
298  for (unsigned int i = 0; i < count; i++) {
299    hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
300					     c->buffer->props.direction,
301					     &c->buffer->pos[i].x_advance,
302					     &c->buffer->pos[i].y_advance);
303    hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
304						 c->buffer->props.direction,
305						 &c->buffer->pos[i].x_offset,
306						 &c->buffer->pos[i].y_offset);
307  }
308}
309
310static void
311hb_ot_position_complex (hb_ot_shape_context_t *c)
312{
313
314  if (hb_ot_layout_has_positioning (c->face))
315  {
316    /* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
317
318    unsigned int count = c->buffer->len;
319    for (unsigned int i = 0; i < count; i++) {
320      hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
321					      HB_DIRECTION_LTR,
322					      &c->buffer->pos[i].x_offset,
323					      &c->buffer->pos[i].y_offset);
324    }
325
326    c->plan->map.position (c->font, c->buffer);
327
328    for (unsigned int i = 0; i < count; i++) {
329      hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
330						   HB_DIRECTION_LTR,
331						   &c->buffer->pos[i].x_offset,
332						   &c->buffer->pos[i].y_offset);
333    }
334
335    c->applied_position_complex = TRUE;
336  }
337
338  hb_ot_layout_position_finish (c->buffer);
339
340  return;
341}
342
343static void
344hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
345{
346  /* TODO Mark pos */
347}
348
349static void
350hb_truetype_kern (hb_ot_shape_context_t *c)
351{
352  /* TODO Check for kern=0 */
353  unsigned int count = c->buffer->len;
354  for (unsigned int i = 1; i < count; i++) {
355    hb_position_t x_kern, y_kern, kern1, kern2;
356    hb_font_get_glyph_kerning_for_direction (c->font,
357					     c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
358					     c->buffer->props.direction,
359					     &x_kern, &y_kern);
360
361    kern1 = x_kern >> 1;
362    kern2 = x_kern - kern1;
363    c->buffer->pos[i - 1].x_advance += kern1;
364    c->buffer->pos[i].x_advance += kern2;
365    c->buffer->pos[i].x_offset += kern2;
366
367    kern1 = y_kern >> 1;
368    kern2 = y_kern - kern1;
369    c->buffer->pos[i - 1].y_advance += kern1;
370    c->buffer->pos[i].y_advance += kern2;
371    c->buffer->pos[i].y_offset += kern2;
372  }
373}
374
375static void
376hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
377{
378  hb_truetype_kern (c);
379}
380
381
382/* Do it! */
383
384static void
385hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
386{
387  c->buffer->deallocate_var_all ();
388
389  /* Save the original direction, we use it later. */
390  c->target_direction = c->buffer->props.direction;
391
392  HB_BUFFER_ALLOCATE_VAR (c->buffer, general_category);
393  HB_BUFFER_ALLOCATE_VAR (c->buffer, combining_class);
394
395  hb_set_unicode_props (c->buffer); /* BUFFER: Set general_category and combining_class */
396
397  hb_form_clusters (c->buffer);
398
399  hb_ensure_native_direction (c->buffer);
400
401  _hb_ot_shape_normalize (c->font, c->buffer, hb_ot_shape_complex_normalization_preference (c->plan->shaper));
402
403  hb_ot_shape_setup_masks (c);
404
405  /* SUBSTITUTE */
406  {
407    hb_substitute_default (c);
408
409    hb_ot_substitute_complex (c);
410  }
411
412  /* POSITION */
413  {
414    hb_position_default (c);
415
416    hb_ot_position_complex (c);
417
418    hb_bool_t position_fallback = !c->applied_position_complex;
419    if (position_fallback)
420      hb_position_complex_fallback (c);
421
422    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
423      hb_buffer_reverse (c->buffer);
424
425    if (position_fallback)
426      hb_position_complex_fallback_visual (c);
427  }
428
429  HB_BUFFER_DEALLOCATE_VAR (c->buffer, combining_class);
430  HB_BUFFER_DEALLOCATE_VAR (c->buffer, general_category);
431
432  c->buffer->props.direction = c->target_direction;
433
434  c->buffer->deallocate_var_all ();
435}
436
437static void
438hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
439			   hb_face_t                *face,
440			   const hb_segment_properties_t  *props,
441			   const hb_feature_t       *user_features,
442			   unsigned int              num_user_features)
443{
444  hb_ot_shape_planner_t planner;
445
446  assert (HB_DIRECTION_IS_VALID (props->direction));
447
448  planner.shaper = hb_ot_shape_complex_categorize (props);
449
450  hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
451
452  planner.compile (face, props, *plan);
453}
454
455static void
456hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
457		     hb_font_t          *font,
458		     hb_buffer_t        *buffer,
459		     const hb_feature_t *user_features,
460		     unsigned int        num_user_features)
461{
462  hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
463  hb_ot_shape_execute_internal (&c);
464}
465
466hb_bool_t
467_hb_ot_shape (hb_font_t          *font,
468	      hb_buffer_t        *buffer,
469	      const hb_feature_t *features,
470	      unsigned int        num_features)
471{
472  hb_ot_shape_plan_t plan;
473
474  buffer->guess_properties ();
475
476  hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
477  hb_ot_shape_execute (&plan, font, buffer, features, num_features);
478
479  return TRUE;
480}
481