hb-ot-shape.cc revision 8f0d7e0c3fd4b05c43ac449be4f374dc2dc56127 
1/*
2 * Copyright (C) 2009,2010  Red Hat, Inc.
3 * Copyright (C) 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_get_general_category_func_t get_general_category = c->buffer->unicode->v.get_general_category;
147  hb_unicode_get_combining_class_func_t get_combining_class = c->buffer->unicode->v.get_combining_class;
148  hb_glyph_info_t *info = c->buffer->info;
149
150  unsigned int count = c->buffer->len;
151  for (unsigned int i = 1; i < count; i++) {
152    info[i].general_category() = get_general_category (info[i].codepoint);
153    info[i].combining_class() = get_combining_class (info[i].codepoint);
154  }
155}
156
157static void
158hb_form_clusters (hb_ot_shape_context_t *c)
159{
160  unsigned int count = c->buffer->len;
161  for (unsigned int i = 1; i < count; i++)
162    if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
163      c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
164}
165
166static void
167hb_ensure_native_direction (hb_ot_shape_context_t *c)
168{
169  hb_direction_t direction = c->buffer->props.direction;
170
171  /* TODO vertical */
172  if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
173      direction != hb_script_get_horizontal_direction (c->buffer->props.script))
174  {
175    hb_buffer_reverse_clusters (c->buffer);
176    c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
177  }
178}
179
180static void
181hb_reset_glyph_infos (hb_ot_shape_context_t *c)
182{
183  unsigned int count = c->buffer->len;
184  for (unsigned int i = 0; i < count; i++)
185    c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
186}
187
188
189/* Substitute */
190
191static void
192hb_mirror_chars (hb_ot_shape_context_t *c)
193{
194  hb_unicode_get_mirroring_func_t get_mirroring = c->buffer->unicode->v.get_mirroring;
195
196  if (HB_DIRECTION_IS_FORWARD (c->target_direction))
197    return;
198
199  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
200
201  unsigned int count = c->buffer->len;
202  for (unsigned int i = 0; i < count; i++) {
203    hb_codepoint_t codepoint = get_mirroring (c->buffer->info[i].codepoint);
204    if (likely (codepoint == c->buffer->info[i].codepoint))
205      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
206    else
207      c->buffer->info[i].codepoint = codepoint;
208  }
209}
210
211static void
212hb_map_glyphs (hb_font_t    *font,
213	       hb_face_t    *face,
214	       hb_buffer_t  *buffer)
215{
216  if (unlikely (!buffer->len))
217    return;
218
219  buffer->clear_output ();
220  unsigned int count = buffer->len - 1;
221  for (buffer->i = 0; buffer->i < count;) {
222    if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
223      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
224      buffer->i++;
225    } else {
226      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
227    }
228  }
229  if (likely (buffer->i < buffer->len))
230    buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
231  buffer->swap ();
232}
233
234static void
235hb_substitute_default (hb_ot_shape_context_t *c)
236{
237  hb_map_glyphs (c->font, c->face, c->buffer);
238}
239
240static void
241hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
242{
243  /* TODO Arabic */
244}
245
246
247/* Position */
248
249static void
250hb_position_default (hb_ot_shape_context_t *c)
251{
252  hb_ot_layout_position_start (c->buffer);
253
254  unsigned int count = c->buffer->len;
255  for (unsigned int i = 0; i < count; i++) {
256    hb_font_get_glyph_advance (c->font, c->face, c->buffer->info[i].codepoint,
257			       &c->buffer->pos[i].x_advance,
258			       &c->buffer->pos[i].y_advance);
259  }
260}
261
262static void
263hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
264{
265  /* TODO Mark pos */
266}
267
268static void
269hb_truetype_kern (hb_ot_shape_context_t *c)
270{
271  /* TODO Check for kern=0 */
272  unsigned int count = c->buffer->len;
273  for (unsigned int i = 1; i < count; i++) {
274    hb_position_t kern, kern1, kern2;
275    kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
276    kern1 = kern >> 1;
277    kern2 = kern - kern1;
278    c->buffer->pos[i - 1].x_advance += kern1;
279    c->buffer->pos[i].x_advance += kern2;
280    c->buffer->pos[i].x_offset += kern2;
281  }
282}
283
284static void
285hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
286{
287  hb_truetype_kern (c);
288}
289
290
291/* Do it! */
292
293static void
294hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
295{
296  /* Save the original direction, we use it later. */
297  c->target_direction = c->buffer->props.direction;
298
299  hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
300
301  hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
302
303  hb_ensure_native_direction (c);
304
305  hb_form_clusters (c);
306
307  hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
308
309  /* SUBSTITUTE */
310  {
311    /* Mirroring needs to see the original direction */
312    hb_mirror_chars (c);
313
314    hb_substitute_default (c);
315
316    hb_ot_substitute_complex (c);
317
318    if (!c->applied_substitute_complex)
319      hb_substitute_complex_fallback (c);
320  }
321
322  /* POSITION */
323  {
324    hb_position_default (c);
325
326    hb_ot_position_complex (c);
327
328    hb_bool_t position_fallback = !c->applied_position_complex;
329    if (position_fallback)
330      hb_position_complex_fallback (c);
331
332    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
333      hb_buffer_reverse (c->buffer);
334
335    if (position_fallback)
336      hb_position_complex_fallback_visual (c);
337  }
338
339  c->buffer->props.direction = c->target_direction;
340}
341
342void
343hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
344			   hb_face_t                *face,
345			   const hb_segment_properties_t  *props,
346			   const hb_feature_t       *user_features,
347			   unsigned int              num_user_features)
348{
349  plan->shaper = hb_ot_shape_complex_categorize (props);
350
351  hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
352
353  plan->map.compile (face, props);
354}
355
356void
357hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
358		     hb_font_t          *font,
359		     hb_face_t          *face,
360		     hb_buffer_t        *buffer,
361		     const hb_feature_t *user_features,
362		     unsigned int        num_user_features)
363{
364  hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
365  hb_ot_shape_execute_internal (&c);
366}
367
368void
369hb_ot_shape (hb_font_t          *font,
370	     hb_face_t          *face,
371	     hb_buffer_t        *buffer,
372	     const hb_feature_t *features,
373	     unsigned int        num_features)
374{
375  hb_ot_shape_plan_t plan;
376
377  hb_ot_shape_plan_internal (&plan, face, &buffer->props, features, num_features);
378  hb_ot_shape_execute (&plan, font, face, buffer, features, num_features);
379}
380
381
382HB_END_DECLS
383