hb-ot-shape.cc revision dd2ffd282c059194fd87fb1664e2e0cdb56a87a0 
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','s','w','h'),
41  HB_TAG('c','u','r','s'),
42  HB_TAG('k','e','r','n'),
43  HB_TAG('l','i','g','a'),
44  HB_TAG('l','o','c','l'),
45  HB_TAG('m','a','r','k'),
46  HB_TAG('m','k','m','k'),
47  HB_TAG('r','l','i','g')
48};
49
50static void
51hb_ot_shape_collect_features (hb_ot_shape_plan_t       *plan,
52			      const hb_segment_properties_t  *props,
53			      const hb_feature_t       *user_features,
54			      unsigned int              num_user_features)
55{
56  switch (props->direction) {
57    case HB_DIRECTION_LTR:
58      plan->map.add_bool_feature (HB_TAG ('l','t','r','a'));
59      plan->map.add_bool_feature (HB_TAG ('l','t','r','m'));
60      break;
61    case HB_DIRECTION_RTL:
62      plan->map.add_bool_feature (HB_TAG ('r','t','l','a'));
63      plan->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
64      break;
65    case HB_DIRECTION_TTB:
66    case HB_DIRECTION_BTT:
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);
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->font, c->face, 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_form_clusters (hb_ot_shape_context_t *c)
145{
146  unsigned int count = c->buffer->len;
147  for (unsigned int i = 1; i < count; i++)
148    if (c->buffer->unicode->v.get_general_category (c->buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
149      c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
150}
151
152static void
153hb_ensure_native_direction (hb_ot_shape_context_t *c)
154{
155  hb_direction_t direction = c->buffer->props.direction;
156
157  /* TODO vertical */
158  if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
159      direction != _hb_script_get_horizontal_direction (c->buffer->props.script))
160  {
161    hb_buffer_reverse_clusters (c->buffer);
162    c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
163  }
164}
165
166
167/* Substitute */
168
169static void
170hb_mirror_chars (hb_ot_shape_context_t *c)
171{
172  hb_unicode_get_mirroring_func_t get_mirroring = c->buffer->unicode->v.get_mirroring;
173
174  if (HB_DIRECTION_IS_FORWARD (c->buffer->props.direction))
175    return;
176
177  hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
178
179  unsigned int count = c->buffer->len;
180  for (unsigned int i = 0; i < count; i++) {
181    hb_codepoint_t codepoint = get_mirroring (c->buffer->info[i].codepoint);
182    if (likely (codepoint == c->buffer->info[i].codepoint))
183      c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
184    else
185      c->buffer->info[i].codepoint = codepoint;
186  }
187}
188
189static void
190hb_map_glyphs (hb_font_t    *font,
191	       hb_face_t    *face,
192	       hb_buffer_t  *buffer)
193{
194  if (unlikely (!buffer->len))
195    return;
196
197  buffer->clear_output ();
198  unsigned int count = buffer->len - 1;
199  for (buffer->i = 0; buffer->i < count;) {
200    if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
201      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
202      buffer->i++;
203    } else {
204      buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
205    }
206  }
207  if (likely (buffer->i < buffer->len))
208    buffer->replace_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
209  buffer->swap ();
210}
211
212static void
213hb_substitute_default (hb_ot_shape_context_t *c)
214{
215  hb_map_glyphs (c->font, c->face, c->buffer);
216}
217
218static void
219hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
220{
221  /* TODO Arabic */
222}
223
224
225/* Position */
226
227static void
228hb_position_default (hb_ot_shape_context_t *c)
229{
230  hb_buffer_clear_positions (c->buffer);
231
232  unsigned int count = c->buffer->len;
233  for (unsigned int i = 0; i < count; i++) {
234    hb_font_get_glyph_advance (c->font, c->face, c->buffer->info[i].codepoint,
235			       &c->buffer->pos[i].x_advance,
236			       &c->buffer->pos[i].y_advance);
237  }
238}
239
240static void
241hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
242{
243  /* TODO Mark pos */
244}
245
246static void
247hb_truetype_kern (hb_ot_shape_context_t *c)
248{
249  /* TODO Check for kern=0 */
250  unsigned int count = c->buffer->len;
251  for (unsigned int i = 1; i < count; i++) {
252    hb_position_t kern, kern1, kern2;
253    kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
254    kern1 = kern >> 1;
255    kern2 = kern - kern1;
256    c->buffer->pos[i - 1].x_advance += kern1;
257    c->buffer->pos[i].x_advance += kern2;
258    c->buffer->pos[i].x_offset += kern2;
259  }
260}
261
262static void
263hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
264{
265  hb_truetype_kern (c);
266}
267
268
269/* Do it! */
270
271static void
272hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
273{
274  /* Save the original direction, we use it later. */
275  c->original_direction = c->buffer->props.direction;
276
277  hb_form_clusters (c);
278
279  hb_ot_shape_setup_masks (c);
280
281  /* SUBSTITUTE */
282  {
283    /* Mirroring needs to see the original direction */
284    hb_mirror_chars (c);
285
286    hb_ensure_native_direction (c);
287
288    hb_substitute_default (c);
289
290    hb_ot_substitute_complex (c);
291
292    if (!c->applied_substitute_complex)
293      hb_substitute_complex_fallback (c);
294  }
295
296  /* POSITION */
297  {
298    hb_position_default (c);
299
300    hb_ot_position_complex (c);
301
302    hb_bool_t position_fallback = !c->applied_position_complex;
303    if (position_fallback)
304      hb_position_complex_fallback (c);
305
306    if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
307      hb_buffer_reverse (c->buffer);
308
309    if (position_fallback)
310      hb_position_complex_fallback_visual (c);
311  }
312
313  c->buffer->props.direction = c->original_direction;
314}
315
316void
317hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
318			   hb_face_t                *face,
319			   const hb_segment_properties_t  *props,
320			   const hb_feature_t       *user_features,
321			   unsigned int              num_user_features)
322{
323  plan->shaper = hb_ot_shape_complex_categorize (props);
324
325  hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
326
327  plan->map.compile (face, props);
328}
329
330void
331hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
332		     hb_font_t          *font,
333		     hb_face_t          *face,
334		     hb_buffer_t        *buffer,
335		     const hb_feature_t *user_features,
336		     unsigned int        num_user_features)
337{
338  hb_ot_shape_context_t c = {plan, font, face, buffer, user_features, num_user_features};
339  hb_ot_shape_execute_internal (&c);
340}
341
342void
343hb_ot_shape (hb_font_t    *font,
344	     hb_face_t    *face,
345	     hb_buffer_t  *buffer,
346	     const hb_feature_t *user_features,
347	     unsigned int        num_user_features)
348{
349  hb_ot_shape_plan_t plan;
350
351  hb_ot_shape_plan_internal (&plan, face, &buffer->props, user_features, num_user_features);
352  hb_ot_shape_execute (&plan, font, face, buffer, user_features, num_user_features);
353}
354
355
356HB_END_DECLS
357