hb-ot-shape.cc revision 2409d5f8d7dd8b535ce5ea29e933f7db27d33793 
1/*
2 * Copyright © 2009,2010  Red Hat, Inc.
3 * Copyright © 2010  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
32HB_BEGIN_DECLS
33
34
35/* XXX vertical */
36hb_tag_t default_features[] = {
37  HB_TAG('c','a','l','t'),
38  HB_TAG('c','c','m','p'),
39  HB_TAG('c','l','i','g'),
40  HB_TAG('c','u','r','s'),
41  HB_TAG('k','e','r','n'),
42  HB_TAG('l','i','g','a'),
43  HB_TAG('l','o','c','l'),
44  HB_TAG('m','a','r','k'),
45  HB_TAG('m','k','m','k'),
46  HB_TAG('r','l','i','g')
47};
48
49static void
50hb_ot_shape_collect_features (hb_ot_shape_plan_t       *plan,
51			      const hb_segment_properties_t  *props,
52			      const hb_feature_t       *user_features,
53			      unsigned int              num_user_features)
54{
55  switch (props->direction) {
56    case HB_DIRECTION_LTR:
57      plan->map.add_bool_feature (HB_TAG ('l','t','r','a'));
58      plan->map.add_bool_feature (HB_TAG ('l','t','r','m'));
59      break;
60    case HB_DIRECTION_RTL:
61      plan->map.add_bool_feature (HB_TAG ('r','t','l','a'));
62      plan->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
63      break;
64    case HB_DIRECTION_TTB:
65    case HB_DIRECTION_BTT:
66    case HB_DIRECTION_INVALID:
67    default:
68      break;
69  }
70
71  for (unsigned int i = 0; i < ARRAY_LENGTH (default_features); i++)
72    plan->map.add_bool_feature (default_features[i]);
73
74  hb_ot_shape_complex_collect_features (plan, props);
75
76  for (unsigned int i = 0; i < num_user_features; i++) {
77    const hb_feature_t *feature = &user_features[i];
78    plan->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
79  }
80}
81
82
83static void
84hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
85{
86  hb_mask_t global_mask = c->plan->map.get_global_mask ();
87  c->buffer->reset_masks (global_mask);
88
89  hb_ot_shape_complex_setup_masks (c); /* BUFFER: Clobbers var2 */
90
91  for (unsigned int i = 0; i < c->num_user_features; i++)
92  {
93    const hb_feature_t *feature = &c->user_features[i];
94    if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
95      unsigned int shift;
96      hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
97      c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
98    }
99  }
100}
101
102
103static void
104hb_ot_substitute_complex (hb_ot_shape_context_t *c)
105{
106  if (!hb_ot_layout_has_substitution (c->face))
107    return;
108
109  c->plan->map.substitute (c->face, c->buffer);
110
111  c->applied_substitute_complex = TRUE;
112  return;
113}
114
115static void
116hb_ot_position_complex (hb_ot_shape_context_t *c)
117{
118
119  if (!hb_ot_layout_has_positioning (c->face))
120    return;
121
122  c->plan->map.position (c->font, c->face, c->buffer);
123
124  hb_ot_layout_position_finish (c->buffer);
125
126  c->applied_position_complex = TRUE;
127  return;
128}
129
130
131/* Main shaper */
132
133/* Prepare */
134
135static inline hb_bool_t
136is_variation_selector (hb_codepoint_t unicode)
137{
138  return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
139		   (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
140		   (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
141}
142
143static void
144hb_set_unicode_props (hb_ot_shape_context_t *c)
145{
146  hb_unicode_funcs_t *unicode = c->buffer->unicode;
147  hb_glyph_info_t *info = c->buffer->info;
148
149  unsigned int count = c->buffer->len;
150  for (unsigned int i = 1; i < count; i++) {
151    info[i].general_category() = unicode->get_general_category (info[i].codepoint);
152    info[i].combining_class() = unicode->get_combining_class (info[i].codepoint);
153  }
154}
155
156static void
157hb_form_clusters (hb_ot_shape_context_t *c)
158{
159  unsigned int count = c->buffer->len;
160  for (unsigned int i = 1; i < count; i++)
161    if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
162      c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
163}
164
165static void
166hb_ensure_native_direction (hb_ot_shape_context_t *c)
167{
168  hb_direction_t direction = c->buffer->props.direction;
169
170  /* TODO vertical */
171  if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
172      direction != hb_script_get_horizontal_direction (c->buffer->props.script))
173  {
174    hb_buffer_reverse_clusters (c->buffer);
175    c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
176  }
177}
178
179static void
180hb_reset_glyph_infos (hb_ot_shape_context_t *c)
181{
182  unsigned int count = c->buffer->len;
183  for (unsigned int i = 0; i < count; i++)
184    c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
185}
186
187
188/* Substitute */
189
190static void
191hb_mirror_chars (hb_ot_shape_context_t *c)
192{
193  hb_unicode_funcs_t *unicode = c->buffer->unicode;
194
195  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
196    return;
197
198  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
199
200  unsigned int count = c->buffer->len;
201  for (unsigned int i = 0; i < count; i++) {
202    hb_codepoint_t codepoint = unicode->get_mirroring (c->buffer->info[i].codepoint);
203    if (likely (codepoint == c->buffer->info[i].codepoint))
204      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
205    else
206      c->buffer->info[i].codepoint = codepoint;
207  }
208}
209
210static void
211hb_map_glyphs (hb_font_t    *font,
212	       hb_face_t    *face,
213	       hb_buffer_t  *buffer)
214{
215  if (unlikely (!buffer->len))
216    return;
217
218  buffer->clear_output ();
219  unsigned int count = buffer->len - 1;
220  for (buffer->i = 0; buffer->i < count;) {
221    if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
222      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
223      buffer->i++;
224    } else {
225      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
226    }
227  }
228  if (likely (buffer->i < buffer->len))
229    buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
230  buffer->swap ();
231}
232
233static void
234hb_substitute_default (hb_ot_shape_context_t *c)
235{
236  hb_map_glyphs (c->font, c->face, c->buffer);
237}
238
239static void
240hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
241{
242  /* TODO Arabic */
243}
244
245
246/* Position */
247
248static void
249hb_position_default (hb_ot_shape_context_t *c)
250{
251  hb_ot_layout_position_start (c->buffer);
252
253  unsigned int count = c->buffer->len;
254  for (unsigned int i = 0; i < count; i++) {
255    hb_font_get_glyph_advance (c->font, c->face, c->buffer->info[i].codepoint,
256			       &c->buffer->pos[i].x_advance,
257			       &c->buffer->pos[i].y_advance);
258  }
259}
260
261static void
262hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
263{
264  /* TODO Mark pos */
265}
266
267static void
268hb_truetype_kern (hb_ot_shape_context_t *c)
269{
270  /* TODO Check for kern=0 */
271  unsigned int count = c->buffer->len;
272  for (unsigned int i = 1; i < count; i++) {
273    hb_position_t kern, kern1, kern2;
274    kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
275    kern1 = kern >> 1;
276    kern2 = kern - kern1;
277    c->buffer->pos[i - 1].x_advance += kern1;
278    c->buffer->pos[i].x_advance += kern2;
279    c->buffer->pos[i].x_offset += kern2;
280  }
281}
282
283static void
284hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
285{
286  hb_truetype_kern (c);
287}
288
289
290/* Do it! */
291
292static void
293hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
294{
295  /* Save the original direction, we use it later. */
296  c->target_direction = c->buffer->props.direction;
297
298  hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
299
300  hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
301
302  hb_ensure_native_direction (c);
303
304  hb_form_clusters (c);
305
306  hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
307
308  /* SUBSTITUTE */
309  {
310    /* Mirroring needs to see the original direction */
311    hb_mirror_chars (c);
312
313    hb_substitute_default (c);
314
315    hb_ot_substitute_complex (c);
316
317    if (!c->applied_substitute_complex)
318      hb_substitute_complex_fallback (c);
319  }
320
321  /* POSITION */
322  {
323    hb_position_default (c);
324
325    hb_ot_position_complex (c);
326
327    hb_bool_t position_fallback = !c->applied_position_complex;
328    if (position_fallback)
329      hb_position_complex_fallback (c);
330
331    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
332      hb_buffer_reverse (c->buffer);
333
334    if (position_fallback)
335      hb_position_complex_fallback_visual (c);
336  }
337
338  c->buffer->props.direction = c->target_direction;
339}
340
341void
342hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
343			   hb_face_t                *face,
344			   const hb_segment_properties_t  *props,
345			   const hb_feature_t       *user_features,
346			   unsigned int              num_user_features)
347{
348  plan->shaper = hb_ot_shape_complex_categorize (props);
349
350  hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
351
352  plan->map.compile (face, props);
353}
354
355void
356hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
357		     hb_font_t          *font,
358		     hb_face_t          *face,
359		     hb_buffer_t        *buffer,
360		     const hb_feature_t *user_features,
361		     unsigned int        num_user_features)
362{
363  hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
364  hb_ot_shape_execute_internal (&c);
365}
366
367void
368hb_ot_shape (hb_font_t          *font,
369	     hb_face_t          *face,
370	     hb_buffer_t        *buffer,
371	     const hb_feature_t *features,
372	     unsigned int        num_features)
373{
374  hb_ot_shape_plan_t plan;
375
376  hb_ot_shape_plan_internal (&plan, face, &buffer->props, features, num_features);
377  hb_ot_shape_execute (&plan, font, face, buffer, features, num_features);
378}
379
380
381HB_END_DECLS
382