hb-ot-shape.cc revision cf7f43ec3382cac2af11f5637c840500daabf889 
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 void
180hb_set_unicode_props (hb_ot_shape_context_t *c)
181{
182  hb_unicode_funcs_t *unicode = c->buffer->unicode;
183  hb_glyph_info_t *info = c->buffer->info;
184
185  unsigned int count = c->buffer->len;
186  for (unsigned int i = 1; i < count; i++) {
187    info[i].general_category() = hb_unicode_general_category (unicode, info[i].codepoint);
188    info[i].combining_class() = hb_unicode_combining_class (unicode, info[i].codepoint);
189  }
190}
191
192static void
193hb_form_clusters (hb_ot_shape_context_t *c)
194{
195  unsigned int count = c->buffer->len;
196  for (unsigned int i = 1; i < count; i++)
197    if (FLAG (c->buffer->info[i].general_category()) &
198	(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
199	 FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
200	 FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)) ||
201        is_variation_selector (c->buffer->info[c->buffer->i].codepoint))
202      c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
203}
204
205static void
206hb_ensure_native_direction (hb_ot_shape_context_t *c)
207{
208  hb_direction_t direction = c->buffer->props.direction;
209
210  /* TODO vertical:
211   * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
212   * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
213   * first. */
214  if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (c->buffer->props.script)) ||
215      (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
216  {
217    hb_buffer_reverse_clusters (c->buffer);
218    c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
219  }
220}
221
222static void
223hb_reset_glyph_infos (hb_ot_shape_context_t *c)
224{
225  unsigned int count = c->buffer->len;
226  for (unsigned int i = 0; i < count; i++)
227    c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
228}
229
230
231/* Substitute */
232
233static void
234hb_mirror_chars (hb_ot_shape_context_t *c)
235{
236  hb_unicode_funcs_t *unicode = c->buffer->unicode;
237
238  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
239    return;
240
241  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
242
243  unsigned int count = c->buffer->len;
244  for (unsigned int i = 0; i < count; i++) {
245    hb_codepoint_t codepoint = hb_unicode_mirroring (unicode, c->buffer->info[i].codepoint);
246    if (likely (codepoint == c->buffer->info[i].codepoint))
247      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
248    else
249      c->buffer->info[i].codepoint = codepoint;
250  }
251}
252
253static void
254hb_map_glyphs (hb_font_t    *font,
255	       hb_buffer_t  *buffer)
256{
257  if (unlikely (!buffer->len))
258    return;
259
260  hb_codepoint_t glyph;
261  buffer->clear_output ();
262  unsigned int count = buffer->len - 1;
263  for (buffer->i = 0; buffer->i < count;) {
264    if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
265      hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint, &glyph);
266      buffer->replace_glyph (glyph);
267      buffer->skip_glyph ();
268    } else {
269      hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
270      buffer->replace_glyph (glyph);
271    }
272  }
273  if (likely (buffer->i < buffer->len)) {
274    hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
275    buffer->replace_glyph (glyph);
276  }
277  buffer->swap ();
278}
279
280static void
281hb_substitute_default (hb_ot_shape_context_t *c)
282{
283  hb_map_glyphs (c->font, c->buffer);
284}
285
286static void
287hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
288{
289  /* TODO Arabic */
290}
291
292
293/* Position */
294
295static void
296hb_position_default (hb_ot_shape_context_t *c)
297{
298  hb_ot_layout_position_start (c->buffer);
299
300  unsigned int count = c->buffer->len;
301  for (unsigned int i = 0; i < count; i++) {
302    hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
303					     c->buffer->props.direction,
304					     &c->buffer->pos[i].x_advance,
305					     &c->buffer->pos[i].y_advance);
306    hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
307						 c->buffer->props.direction,
308						 &c->buffer->pos[i].x_offset,
309						 &c->buffer->pos[i].y_offset);
310  }
311}
312
313static void
314hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
315{
316  /* TODO Mark pos */
317}
318
319static void
320hb_truetype_kern (hb_ot_shape_context_t *c)
321{
322  /* TODO Check for kern=0 */
323  unsigned int count = c->buffer->len;
324  for (unsigned int i = 1; i < count; i++) {
325    hb_position_t x_kern, y_kern, kern1, kern2;
326    hb_font_get_glyph_kerning_for_direction (c->font,
327					     c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
328					     c->buffer->props.direction,
329					     &x_kern, &y_kern);
330
331    kern1 = x_kern >> 1;
332    kern2 = x_kern - kern1;
333    c->buffer->pos[i - 1].x_advance += kern1;
334    c->buffer->pos[i].x_advance += kern2;
335    c->buffer->pos[i].x_offset += kern2;
336
337    kern1 = y_kern >> 1;
338    kern2 = y_kern - kern1;
339    c->buffer->pos[i - 1].y_advance += kern1;
340    c->buffer->pos[i].y_advance += kern2;
341    c->buffer->pos[i].y_offset += kern2;
342  }
343}
344
345static void
346hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
347{
348  hb_truetype_kern (c);
349}
350
351
352/* Do it! */
353
354static void
355hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
356{
357  /* Save the original direction, we use it later. */
358  c->target_direction = c->buffer->props.direction;
359
360  hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
361
362  hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
363
364  hb_form_clusters (c);
365
366  hb_ensure_native_direction (c);
367
368  _hb_normalize (c);
369
370  hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
371
372  /* SUBSTITUTE */
373  {
374    hb_mirror_chars (c);
375
376    hb_substitute_default (c);
377
378    hb_ot_substitute_complex (c);
379
380    if (!c->applied_substitute_complex)
381      hb_substitute_complex_fallback (c);
382  }
383
384  /* POSITION */
385  {
386    hb_position_default (c);
387
388    hb_ot_position_complex (c);
389
390    hb_bool_t position_fallback = !c->applied_position_complex;
391    if (position_fallback)
392      hb_position_complex_fallback (c);
393
394    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
395      hb_buffer_reverse (c->buffer);
396
397    if (position_fallback)
398      hb_position_complex_fallback_visual (c);
399  }
400
401  c->buffer->props.direction = c->target_direction;
402}
403
404static void
405hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
406			   hb_face_t                *face,
407			   const hb_segment_properties_t  *props,
408			   const hb_feature_t       *user_features,
409			   unsigned int              num_user_features)
410{
411  hb_ot_shape_planner_t planner;
412
413  planner.shaper = hb_ot_shape_complex_categorize (props);
414
415  hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
416
417  planner.compile (face, props, *plan);
418}
419
420static void
421hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
422		     hb_font_t          *font,
423		     hb_buffer_t        *buffer,
424		     const hb_feature_t *user_features,
425		     unsigned int        num_user_features)
426{
427  hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
428  hb_ot_shape_execute_internal (&c);
429}
430
431void
432hb_ot_shape (hb_font_t          *font,
433	     hb_buffer_t        *buffer,
434	     const hb_feature_t *features,
435	     unsigned int        num_features)
436{
437  hb_ot_shape_plan_t plan;
438
439  hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
440  hb_ot_shape_execute (&plan, font, buffer, features, num_features);
441}
442
443
444HB_END_DECLS
445