hb-shape.cc revision f64b2ebf82c5f355cd95806478cd30c00b1a2731 
1/*
2 * Copyright © 2009  Red Hat, Inc.
3 *
4 *  This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Red Hat Author(s): Behdad Esfahbod
25 */
26
27#include "hb-private.hh"
28
29#include "hb-shape.h"
30
31#include "hb-buffer-private.hh"
32
33#ifdef HAVE_GRAPHITE
34#include "hb-graphite2-private.hh"
35#endif
36#ifdef HAVE_UNISCRIBE
37# include "hb-uniscribe-private.hh"
38#endif
39#ifdef HAVE_OT
40# include "hb-ot-shape-private.hh"
41#endif
42#include "hb-fallback-shape-private.hh"
43
44typedef hb_bool_t (*hb_shape_func_t) (hb_font_t          *font,
45				      hb_buffer_t        *buffer,
46				      const hb_feature_t *features,
47				      unsigned int        num_features);
48
49#define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape}
50static const struct hb_shaper_pair_t {
51  char name[16];
52  hb_shape_func_t func;
53} all_shapers[] = {
54  /* v--- Add new shapers in the right place here */
55#ifdef HAVE_GRAPHITE
56  HB_SHAPER_IMPLEMENT (graphite2),
57#endif
58#ifdef HAVE_UNISCRIBE
59  HB_SHAPER_IMPLEMENT (uniscribe),
60#endif
61#ifdef HAVE_OT
62  HB_SHAPER_IMPLEMENT (ot),
63#endif
64  HB_SHAPER_IMPLEMENT (fallback) /* should be last */
65};
66#undef HB_SHAPER_IMPLEMENT
67
68
69/* Thread-safe, lock-free, shapers */
70
71static hb_shaper_pair_t *static_shapers;
72
73static
74void free_static_shapers (void)
75{
76  if (unlikely (static_shapers != all_shapers))
77    free (static_shapers);
78}
79
80static const hb_shaper_pair_t *
81get_shapers (void)
82{
83retry:
84  hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);
85
86  if (unlikely (!shapers))
87  {
88    char *env = getenv ("HB_SHAPER_LIST");
89    if (!env || !*env) {
90      hb_atomic_ptr_cmpexch (&static_shapers, NULL, (const hb_shaper_pair_t *) all_shapers);
91      return (const hb_shaper_pair_t *) all_shapers;
92    }
93
94    /* Not found; allocate one. */
95    shapers = (hb_shaper_pair_t *) malloc (sizeof (all_shapers));
96    if (unlikely (!shapers))
97      return (const hb_shaper_pair_t *) all_shapers;
98     memcpy (shapers, all_shapers, sizeof (all_shapers));
99
100     /* Reorder shaper list to prefer requested shapers. */
101    unsigned int i = 0;
102    char *end, *p = env;
103    for (;;) {
104      end = strchr (p, ',');
105      if (!end)
106	end = p + strlen (p);
107
108      for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
109	if (end - p == (int) strlen (shapers[j].name) &&
110	    0 == strncmp (shapers[j].name, p, end - p))
111	{
112	  /* Reorder this shaper to position i */
113	 struct hb_shaper_pair_t t = shapers[j];
114	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
115	 shapers[i] = t;
116	 i++;
117	}
118
119      if (!*end)
120	break;
121      else
122	p = end + 1;
123    }
124
125    if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {
126      free (shapers);
127      goto retry;
128    }
129
130#ifdef HAVE_ATEXIT
131    atexit (free_static_shapers); /* First person registers atexit() callback. */
132#endif
133  }
134
135  return shapers;
136}
137
138
139static const char **static_shaper_list;
140
141static
142void free_static_shaper_list (void)
143{
144  free (static_shaper_list);
145}
146
147const char **
148hb_shape_list_shapers (void)
149{
150retry:
151  const char **shaper_list = (const char **) hb_atomic_ptr_get (&static_shaper_list);
152
153  if (unlikely (!shaper_list))
154  {
155    /* Not found; allocate one. */
156    shaper_list = (const char **) calloc (1 + ARRAY_LENGTH (all_shapers), sizeof (const char *));
157    if (unlikely (!shaper_list)) {
158      static const char *nil_shaper_list[] = {NULL};
159      return nil_shaper_list;
160    }
161
162    const hb_shaper_pair_t *shapers = get_shapers ();
163    unsigned int i;
164    for (i = 0; i < ARRAY_LENGTH (all_shapers); i++)
165      shaper_list[i] = shapers[i].name;
166    shaper_list[i] = NULL;
167
168    if (!hb_atomic_ptr_cmpexch (&static_shaper_list, NULL, shaper_list)) {
169      free (shaper_list);
170      goto retry;
171    }
172
173#ifdef HAVE_ATEXIT
174    atexit (free_static_shaper_list); /* First person registers atexit() callback. */
175#endif
176  }
177
178  return shaper_list;
179}
180
181
182hb_bool_t
183hb_shape_full (hb_font_t          *font,
184	       hb_buffer_t        *buffer,
185	       const hb_feature_t *features,
186	       unsigned int        num_features,
187	       const char * const *shaper_list)
188{
189  hb_font_make_immutable (font); /* So we can safely cache stuff on it */
190
191  if (likely (!shaper_list)) {
192    const hb_shaper_pair_t *shapers = get_shapers ();
193    for (unsigned int i = 0; i < ARRAY_LENGTH (all_shapers); i++)
194      if (likely (shapers[i].func (font, buffer, features, num_features)))
195        return TRUE;
196  } else {
197    while (*shaper_list) {
198      for (unsigned int i = 0; i < ARRAY_LENGTH (all_shapers); i++)
199	if (0 == strcmp (*shaper_list, all_shapers[i].name)) {
200	  if (likely (all_shapers[i].func (font, buffer, features, num_features)))
201	    return TRUE;
202	  break;
203	}
204      shaper_list++;
205    }
206  }
207  return FALSE;
208}
209
210void
211hb_shape (hb_font_t           *font,
212	  hb_buffer_t         *buffer,
213	  const hb_feature_t  *features,
214	  unsigned int         num_features)
215{
216  hb_shape_full (font, buffer, features, num_features, NULL);
217}
218