hb-ot-shape.cc revision f6fd3780e12b23ff7ed3743497c8996e71dcb064 
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-complex-private.hh"
31
32#include "hb-font-private.hh"
33
34HB_BEGIN_DECLS
35
36
37hb_tag_t common_features[] = {
38  HB_TAG('c','c','m','p'),
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  HB_TAG('l','i','g','a'),
51};
52
53/* Note:
54 * Technically speaking, vrt2 and vert are mutually exclusive.
55 * According to the spec, valt and vpal are also mutually exclusive.
56 * But we apply them all for now.
57 */
58hb_tag_t vertical_features[] = {
59  HB_TAG('v','a','l','t'),
60  HB_TAG('v','e','r','t'),
61  HB_TAG('v','k','r','n'),
62  HB_TAG('v','p','a','l'),
63  HB_TAG('v','r','t','2'),
64};
65
66static void
67hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
68			      const hb_segment_properties_t  *props,
69			      const hb_feature_t             *user_features,
70			      unsigned int                    num_user_features)
71{
72  switch (props->direction) {
73    case HB_DIRECTION_LTR:
74      planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
75      planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
76      break;
77    case HB_DIRECTION_RTL:
78      planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
79      planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
80      break;
81    case HB_DIRECTION_TTB:
82    case HB_DIRECTION_BTT:
83    case HB_DIRECTION_INVALID:
84    default:
85      break;
86  }
87
88#define ADD_FEATURES(array) \
89  HB_STMT_START { \
90    for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
91      planner->map.add_bool_feature (array[i]); \
92  } HB_STMT_END
93
94  hb_ot_shape_complex_collect_features (planner->shaper, &planner->map, props);
95
96  ADD_FEATURES (common_features);
97
98  if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
99    ADD_FEATURES (horizontal_features);
100  else
101    ADD_FEATURES (vertical_features);
102
103#undef ADD_FEATURES
104
105  for (unsigned int i = 0; i < num_user_features; i++) {
106    const hb_feature_t *feature = &user_features[i];
107    planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
108  }
109}
110
111
112static void
113hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
114{
115  hb_mask_t global_mask = c->plan->map.get_global_mask ();
116  c->buffer->reset_masks (global_mask);
117
118  hb_ot_shape_complex_setup_masks (c->plan->shaper, &c->plan->map, c->buffer); /* BUFFER: Clobbers var2 */
119
120  for (unsigned int i = 0; i < c->num_user_features; i++)
121  {
122    const hb_feature_t *feature = &c->user_features[i];
123    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
124      unsigned int shift;
125      hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
126      c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
127    }
128  }
129}
130
131
132static void
133hb_ot_substitute_complex (hb_ot_shape_context_t *c)
134{
135  if (!hb_ot_layout_has_substitution (c->face))
136    return;
137
138  c->plan->map.substitute (c->face, c->buffer);
139
140  c->applied_substitute_complex = TRUE;
141  return;
142}
143
144static void
145hb_ot_position_complex (hb_ot_shape_context_t *c)
146{
147
148  if (!hb_ot_layout_has_positioning (c->face))
149    return;
150
151  unsigned int count = c->buffer->len;
152  for (unsigned int i = 0; i < count; i++) {
153    hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
154					    HB_DIRECTION_LTR,
155					    &c->buffer->pos[i].x_offset,
156					    &c->buffer->pos[i].y_offset);
157  }
158
159  c->plan->map.position (c->font, c->buffer);
160
161  for (unsigned int i = 0; i < count; i++) {
162    hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
163						 HB_DIRECTION_LTR,
164						 &c->buffer->pos[i].x_offset,
165						 &c->buffer->pos[i].y_offset);
166  }
167
168  hb_ot_layout_position_finish (c->buffer);
169
170  c->applied_position_complex = TRUE;
171  return;
172}
173
174
175/* Main shaper */
176
177/* Prepare */
178
179static inline hb_bool_t
180is_variation_selector (hb_codepoint_t unicode)
181{
182  return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
183		   (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
184		   (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
185}
186
187static void
188hb_set_unicode_props (hb_ot_shape_context_t *c)
189{
190  hb_unicode_funcs_t *unicode = c->buffer->unicode;
191  hb_glyph_info_t *info = c->buffer->info;
192
193  unsigned int count = c->buffer->len;
194  for (unsigned int i = 1; i < count; i++) {
195    info[i].general_category() = hb_unicode_general_category (unicode, info[i].codepoint);
196    info[i].combining_class() = hb_unicode_combining_class (unicode, info[i].codepoint);
197  }
198}
199
200static void
201hb_form_clusters (hb_ot_shape_context_t *c)
202{
203  unsigned int count = c->buffer->len;
204  for (unsigned int i = 1; i < count; i++)
205    /* TODO: Match other mark types too? */
206    if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
207      c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
208}
209
210static void
211hb_ensure_native_direction (hb_ot_shape_context_t *c)
212{
213  hb_direction_t direction = c->buffer->props.direction;
214
215  /* TODO vertical:
216   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
217   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
218   * first. */
219  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (c->buffer->props.script)) ||
220      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
221  {
222    hb_buffer_reverse_clusters (c->buffer);
223    c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
224  }
225}
226
227static void
228hb_reset_glyph_infos (hb_ot_shape_context_t *c)
229{
230  unsigned int count = c->buffer->len;
231  for (unsigned int i = 0; i < count; i++)
232    c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
233}
234
235
236/* Substitute */
237
238static void
239hb_mirror_chars (hb_ot_shape_context_t *c)
240{
241  hb_unicode_funcs_t *unicode = c->buffer->unicode;
242
243  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
244    return;
245
246  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
247
248  unsigned int count = c->buffer->len;
249  for (unsigned int i = 0; i < count; i++) {
250    hb_codepoint_t codepoint = hb_unicode_mirroring (unicode, c->buffer->info[i].codepoint);
251    if (likely (codepoint == c->buffer->info[i].codepoint))
252      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
253    else
254      c->buffer->info[i].codepoint = codepoint;
255  }
256}
257
258static void
259hb_map_glyphs (hb_font_t    *font,
260	       hb_buffer_t  *buffer)
261{
262  if (unlikely (!buffer->len))
263    return;
264
265  hb_codepoint_t glyph;
266  buffer->clear_output ();
267  unsigned int count = buffer->len - 1;
268  for (buffer->i = 0; buffer->i < count;) {
269    if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
270      hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint, &glyph);
271      buffer->replace_glyph (glyph);
272      buffer->i++;
273    } else {
274      hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
275      buffer->replace_glyph (glyph);
276    }
277  }
278  if (likely (buffer->i < buffer->len)) {
279    hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
280    buffer->replace_glyph (glyph);
281  }
282  buffer->swap ();
283}
284
285static void
286hb_substitute_default (hb_ot_shape_context_t *c)
287{
288  hb_map_glyphs (c->font, c->buffer);
289}
290
291static void
292hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
293{
294  /* TODO Arabic */
295}
296
297
298/* Position */
299
300static void
301hb_position_default (hb_ot_shape_context_t *c)
302{
303  hb_ot_layout_position_start (c->buffer);
304
305  unsigned int count = c->buffer->len;
306  for (unsigned int i = 0; i < count; i++) {
307    hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
308					     c->buffer->props.direction,
309					     &c->buffer->pos[i].x_advance,
310					     &c->buffer->pos[i].y_advance);
311    hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
312						 c->buffer->props.direction,
313						 &c->buffer->pos[i].x_offset,
314						 &c->buffer->pos[i].y_offset);
315  }
316}
317
318static void
319hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
320{
321  /* TODO Mark pos */
322}
323
324static void
325hb_truetype_kern (hb_ot_shape_context_t *c)
326{
327  /* TODO Check for kern=0 */
328  unsigned int count = c->buffer->len;
329  for (unsigned int i = 1; i < count; i++) {
330    hb_position_t x_kern, y_kern, kern1, kern2;
331    hb_font_get_glyph_kerning_for_direction (c->font,
332					     c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
333					     c->buffer->props.direction,
334					     &x_kern, &y_kern);
335
336    kern1 = x_kern >> 1;
337    kern2 = x_kern - kern1;
338    c->buffer->pos[i - 1].x_advance += kern1;
339    c->buffer->pos[i].x_advance += kern2;
340    c->buffer->pos[i].x_offset += kern2;
341
342    kern1 = y_kern >> 1;
343    kern2 = y_kern - kern1;
344    c->buffer->pos[i - 1].y_advance += kern1;
345    c->buffer->pos[i].y_advance += kern2;
346    c->buffer->pos[i].y_offset += kern2;
347  }
348}
349
350static void
351hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
352{
353  hb_truetype_kern (c);
354}
355
356
357/* Do it! */
358
359static void
360hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
361{
362  /* Save the original direction, we use it later. */
363  c->target_direction = c->buffer->props.direction;
364
365  hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
366
367  hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
368
369  hb_ensure_native_direction (c);
370
371  hb_form_clusters (c);
372
373  hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
374
375  /* SUBSTITUTE */
376  {
377    /* Mirroring needs to see the original direction */
378    hb_mirror_chars (c);
379
380    hb_substitute_default (c);
381
382    hb_ot_substitute_complex (c);
383
384    if (!c->applied_substitute_complex)
385      hb_substitute_complex_fallback (c);
386  }
387
388  /* POSITION */
389  {
390    hb_position_default (c);
391
392    hb_ot_position_complex (c);
393
394    hb_bool_t position_fallback = !c->applied_position_complex;
395    if (position_fallback)
396      hb_position_complex_fallback (c);
397
398    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
399      hb_buffer_reverse (c->buffer);
400
401    if (position_fallback)
402      hb_position_complex_fallback_visual (c);
403  }
404
405  c->buffer->props.direction = c->target_direction;
406}
407
408static void
409hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
410			   hb_face_t                *face,
411			   const hb_segment_properties_t  *props,
412			   const hb_feature_t       *user_features,
413			   unsigned int              num_user_features)
414{
415  hb_ot_shape_planner_t planner;
416
417  planner.shaper = hb_ot_shape_complex_categorize (props);
418
419  hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
420
421  planner.compile (face, props, *plan);
422}
423
424static void
425hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
426		     hb_font_t          *font,
427		     hb_buffer_t        *buffer,
428		     const hb_feature_t *user_features,
429		     unsigned int        num_user_features)
430{
431  hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
432  hb_ot_shape_execute_internal (&c);
433}
434
435void
436hb_ot_shape (hb_font_t          *font,
437	     hb_buffer_t        *buffer,
438	     const hb_feature_t *features,
439	     unsigned int        num_features)
440{
441  hb_ot_shape_plan_t plan;
442
443  hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
444  hb_ot_shape_execute (&plan, font, buffer, features, num_features);
445}
446
447
448HB_END_DECLS
449