hb-ot-shape.cc revision 9722b8f005a10fd16e841df4da3ccd80be66e296 
1/*
2 * Copyright (C) 2009  Red Hat, Inc.
3 *
4 *  This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Red Hat Author(s): Behdad Esfahbod
25 */
26
27#include "hb-ot-shape.h"
28
29#include "hb-buffer-private.hh"
30
31#include "hb-ot-layout.h"
32
33hb_tag_t default_features[] = {
34  /* GSUB */
35  HB_TAG('c','c','m','p'),
36  HB_TAG('l','o','c','l'),
37  HB_TAG('l','i','g','a'),
38  HB_TAG('c','l','i','g'),
39  /* GPOS */
40  HB_TAG('k','e','r','n'),
41  HB_TAG('m','a','r','k'),
42  HB_TAG('m','k','m','k'),
43};
44
45struct lookup_map {
46  unsigned int index;
47  hb_mask_t mask;
48};
49
50
51static void
52add_feature (hb_face_t    *face,
53	     hb_tag_t      table_tag,
54	     unsigned int  feature_index,
55	     hb_mask_t     mask,
56	     lookup_map   *lookups,
57	     unsigned int *num_lookups,
58	     unsigned int  room_lookups)
59{
60  unsigned int i = room_lookups - *num_lookups;
61  lookups += *num_lookups;
62
63  unsigned int *lookup_indices = (unsigned int *) lookups;
64
65  hb_ot_layout_feature_get_lookup_indexes (face, table_tag, feature_index, 0,
66					   &i,
67					   lookup_indices);
68
69  *num_lookups += i;
70
71  while (i--) {
72    lookups[i].mask = mask;
73    lookups[i].index = lookup_indices[i];
74  }
75}
76
77static int
78cmp_lookups (const void *p1, const void *p2)
79{
80  const lookup_map *a = (const lookup_map *) p1;
81  const lookup_map *b = (const lookup_map *) p2;
82
83  return a->index - b->index;
84}
85
86static void
87setup_lookups (hb_face_t    *face,
88	       hb_buffer_t  *buffer,
89	       hb_feature_t *features,
90	       unsigned int  num_features,
91	       hb_tag_t      table_tag,
92	       lookup_map   *lookups,
93	       unsigned int *num_lookups)
94{
95  unsigned int i, j, script_index, language_index, feature_index, room_lookups;
96
97  room_lookups = *num_lookups;
98  *num_lookups = 0;
99
100  hb_ot_layout_table_choose_script (face, table_tag,
101				    hb_ot_tags_from_script (buffer->script),
102				    &script_index);
103  hb_ot_layout_script_find_language (face, table_tag, script_index,
104				     hb_ot_tag_from_language (buffer->language),
105				     &language_index);
106
107  if (hb_ot_layout_language_get_required_feature_index (face, table_tag, script_index, language_index,
108							&feature_index))
109    add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
110
111  for (i = 0; i < ARRAY_LENGTH (default_features); i++)
112  {
113    if (hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
114					    default_features[i],
115					    &feature_index))
116      add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups);
117  }
118
119  /* Clear buffer masks. */
120  unsigned int count = buffer->len;
121  for (unsigned int i = 0; i < count; i++)
122    buffer->info[i].mask = 1;
123
124  unsigned int last_bit_used = 1;
125  unsigned int global_values = 0;
126  for (i = 0; i < num_features; i++)
127  {
128    if (!hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index,
129					     features[i].tag,
130					     &feature_index))
131      continue;
132
133    unsigned int bits_needed = _hb_bit_storage (features[i].value);
134    if (!bits_needed)
135      continue;
136    unsigned int mask = (1 << (last_bit_used + bits_needed)) - (1 << last_bit_used);
137    unsigned int value = features[i].value << last_bit_used;
138    last_bit_used += bits_needed;
139
140    add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups);
141
142    if (features[i].start == 0 && features[i].end == (unsigned int)-1)
143      global_values |= value;
144    else
145    {
146      unsigned int start = features[i].start, end = features[i].end;
147      unsigned int a = 0, b = buffer->len;
148      while (a < b)
149      {
150        unsigned int h = a + ((b - a) / 2);
151        if (buffer->info[h].cluster < start)
152          a = h + 1;
153        else
154          b = h;
155      }
156      unsigned int count = buffer->len;
157      for (unsigned int j = a; j < count && buffer->info[j].cluster < end; j++)
158        buffer->info[j].mask |= value;
159    }
160  }
161
162  if (global_values)
163  {
164    unsigned int count = buffer->len;
165    for (unsigned int j = 0; j < count; j++)
166      buffer->info[j].mask |= global_values;
167  }
168
169  qsort (lookups, *num_lookups, sizeof (lookups[0]), cmp_lookups);
170
171  if (*num_lookups)
172  {
173    for (i = 1, j = 0; i < *num_lookups; i++)
174      if (lookups[i].index != lookups[j].index)
175	lookups[++j] = lookups[i];
176      else
177        lookups[j].mask |= lookups[i].mask;
178    j++;
179    *num_lookups = j;
180  }
181}
182
183
184static hb_bool_t
185hb_ot_substitute_complex (hb_font_t    *font HB_UNUSED,
186			  hb_face_t    *face,
187			  hb_buffer_t  *buffer,
188			  hb_feature_t *features,
189			  unsigned int  num_features)
190{
191  lookup_map lookups[1000];
192  unsigned int num_lookups = ARRAY_LENGTH (lookups);
193  unsigned int i;
194
195  if (!hb_ot_layout_has_substitution (face))
196    return FALSE;
197
198  setup_lookups (face, buffer, features, num_features,
199		 HB_OT_TAG_GSUB,
200		 lookups, &num_lookups);
201
202  for (i = 0; i < num_lookups; i++)
203    hb_ot_layout_substitute_lookup (face, buffer, lookups[i].index, lookups[i].mask);
204
205  return TRUE;
206}
207
208static hb_bool_t
209hb_ot_position_complex (hb_font_t    *font,
210			hb_face_t    *face,
211			hb_buffer_t  *buffer,
212			hb_feature_t *features,
213			unsigned int  num_features)
214{
215  lookup_map lookups[1000];
216  unsigned int num_lookups = ARRAY_LENGTH (lookups);
217  unsigned int i;
218
219  if (!hb_ot_layout_has_positioning (face))
220    return FALSE;
221
222  setup_lookups (face, buffer, features, num_features,
223		 HB_OT_TAG_GPOS,
224		 lookups, &num_lookups);
225
226  for (i = 0; i < num_lookups; i++)
227    hb_ot_layout_position_lookup (font, face, buffer, lookups[i].index, lookups[i].mask);
228
229  hb_ot_layout_position_finish (font, face, buffer);
230
231  return TRUE;
232}
233
234
235/* Main shaper */
236
237/* Prepare */
238
239static inline hb_bool_t
240is_variation_selector (hb_codepoint_t unicode)
241{
242  return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
243		   (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
244		   (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
245}
246
247static void
248hb_form_clusters (hb_buffer_t *buffer)
249{
250  unsigned int count = buffer->len;
251  for (unsigned int i = 1; i < count; i++)
252    if (buffer->unicode->get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
253      buffer->info[i].cluster = buffer->info[i - 1].cluster;
254}
255
256static hb_direction_t
257hb_ensure_native_direction (hb_buffer_t *buffer)
258{
259  hb_direction_t original_direction = buffer->direction;
260
261  /* TODO vertical */
262  if (HB_DIRECTION_IS_HORIZONTAL (original_direction) &&
263      original_direction != _hb_script_get_horizontal_direction (buffer->script))
264  {
265    hb_buffer_reverse_clusters (buffer);
266    buffer->direction = HB_DIRECTION_REVERSE (buffer->direction);
267  }
268
269  return original_direction;
270}
271
272
273/* Substitute */
274
275static void
276hb_mirror_chars (hb_buffer_t *buffer)
277{
278  hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->get_mirroring;
279
280  if (HB_DIRECTION_IS_FORWARD (buffer->direction))
281    return;
282
283  unsigned int count = buffer->len;
284  for (unsigned int i = 0; i < count; i++) {
285      buffer->info[i].codepoint = get_mirroring (buffer->info[i].codepoint);
286  }
287}
288
289static void
290hb_map_glyphs (hb_font_t    *font,
291	       hb_face_t    *face,
292	       hb_buffer_t  *buffer)
293{
294  if (unlikely (!buffer->len))
295    return;
296
297  unsigned int count = buffer->len - 1;
298  for (unsigned int i = 0; i < count; i++) {
299    if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) {
300      buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint);
301      i++;
302    } else {
303      buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0);
304    }
305  }
306  buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0);
307}
308
309static void
310hb_substitute_default (hb_font_t    *font,
311		       hb_face_t    *face,
312		       hb_buffer_t  *buffer,
313		       hb_feature_t *features HB_UNUSED,
314		       unsigned int  num_features HB_UNUSED)
315{
316  hb_mirror_chars (buffer);
317  hb_map_glyphs (font, face, buffer);
318}
319
320static void
321hb_substitute_complex_fallback (hb_font_t    *font HB_UNUSED,
322				hb_face_t    *face HB_UNUSED,
323				hb_buffer_t  *buffer HB_UNUSED,
324				hb_feature_t *features HB_UNUSED,
325				unsigned int  num_features HB_UNUSED)
326{
327  /* TODO Arabic */
328}
329
330
331/* Position */
332
333static void
334hb_position_default (hb_font_t    *font,
335		     hb_face_t    *face,
336		     hb_buffer_t  *buffer,
337		     hb_feature_t *features HB_UNUSED,
338		     unsigned int  num_features HB_UNUSED)
339{
340  hb_buffer_clear_positions (buffer);
341
342  unsigned int count = buffer->len;
343  for (unsigned int i = 0; i < count; i++) {
344    hb_glyph_metrics_t metrics;
345    hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics);
346    buffer->pos[i].x_advance = metrics.x_advance;
347    buffer->pos[i].y_advance = metrics.y_advance;
348  }
349}
350
351static void
352hb_position_complex_fallback (hb_font_t    *font HB_UNUSED,
353			      hb_face_t    *face HB_UNUSED,
354			      hb_buffer_t  *buffer HB_UNUSED,
355			      hb_feature_t *features HB_UNUSED,
356			      unsigned int  num_features HB_UNUSED)
357{
358  /* TODO Mark pos */
359}
360
361static void
362hb_truetype_kern (hb_font_t    *font,
363		  hb_face_t    *face,
364		  hb_buffer_t  *buffer,
365		  hb_feature_t *features HB_UNUSED,
366		  unsigned int  num_features HB_UNUSED)
367{
368  /* TODO Check for kern=0 */
369  unsigned int count = buffer->len;
370  for (unsigned int i = 1; i < count; i++) {
371    hb_position_t kern, kern1, kern2;
372    kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint);
373    kern1 = kern >> 1;
374    kern2 = kern - kern1;
375    buffer->pos[i - 1].x_advance += kern1;
376    buffer->pos[i].x_advance += kern2;
377    buffer->pos[i].x_offset += kern2;
378  }
379}
380
381static void
382hb_position_complex_fallback_visual (hb_font_t    *font,
383				     hb_face_t    *face,
384				     hb_buffer_t  *buffer,
385				     hb_feature_t *features,
386				     unsigned int  num_features)
387{
388  hb_truetype_kern (font, face, buffer, features, num_features);
389}
390
391
392/* Do it! */
393
394void
395hb_ot_shape (hb_font_t    *font,
396	     hb_face_t    *face,
397	     hb_buffer_t  *buffer,
398	     hb_feature_t *features,
399	     unsigned int  num_features)
400{
401  hb_direction_t original_direction;
402  hb_bool_t substitute_fallback, position_fallback;
403
404  hb_form_clusters (buffer);
405
406  hb_substitute_default (font, face, buffer, features, num_features);
407
408  /* We do this after substitute_default because mirroring needs to
409   * see the original direction. */
410  original_direction = hb_ensure_native_direction (buffer);
411
412  substitute_fallback = !hb_ot_substitute_complex (font, face, buffer, features, num_features);
413
414  if (substitute_fallback)
415    hb_substitute_complex_fallback (font, face, buffer, features, num_features);
416
417  hb_position_default (font, face, buffer, features, num_features);
418
419  position_fallback = !hb_ot_position_complex (font, face, buffer, features, num_features);
420
421  if (position_fallback)
422    hb_position_complex_fallback (font, face, buffer, features, num_features);
423
424  if (HB_DIRECTION_IS_BACKWARD (buffer->direction))
425    hb_buffer_reverse (buffer);
426
427  if (position_fallback)
428    hb_position_complex_fallback_visual (font, face, buffer, features, num_features);
429
430  buffer->direction = original_direction;
431}
432