50f2986c02c3b9d596ffe525f78498df707b0992
[framework/uifw/harfbuzz.git] / src / hb-ot-shape.cc
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
34 HB_BEGIN_DECLS
35
36
37 hb_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
45 hb_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  */
58 hb_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
66 static void
67 hb_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
112 static void
113 hb_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
132 static void
133 hb_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
144 static void
145 hb_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
179 static void
180 hb_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
192 static void
193 hb_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
205 static void
206 hb_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
222 static void
223 hb_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
233 static void
234 hb_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
253 static void
254 hb_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
280 static void
281 hb_substitute_default (hb_ot_shape_context_t *c)
282 {
283   hb_map_glyphs (c->font, c->buffer);
284 }
285
286 static void
287 hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
288 {
289   /* TODO Arabic */
290 }
291
292
293 /* Position */
294
295 static void
296 hb_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
313 static void
314 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
315 {
316   /* TODO Mark pos */
317 }
318
319 static void
320 hb_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
345 static void
346 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
347 {
348   hb_truetype_kern (c);
349 }
350
351
352 /* Do it! */
353
354 static void
355 hb_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
404 static void
405 hb_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
420 static void
421 hb_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
431 void
432 hb_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
444 HB_END_DECLS