third_party/harfbuzz-ng/src/hb-shape.cc

   1 /*
   2  * Copyright © 2009  Red Hat, Inc.
   3  * Copyright © 2012  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-private.hh"
  30
  31 #include "hb-shaper-private.hh"
  32 #include "hb-shape-plan-private.hh"
  33 #include "hb-buffer-private.hh"
  34 #include "hb-font-private.hh"
  35
  36
  37 static bool
  38 parse_space (const char **pp, const char *end)
  39 {
  40   while (*pp < end && ISSPACE (**pp))
  41     (*pp)++;
  42   return true;
  43 }
  44
  45 static bool
  46 parse_char (const char **pp, const char *end, char c)
  47 {
  48   parse_space (pp, end);
  49
  50   if (*pp == end || **pp != c)
  51     return false;
  52
  53   (*pp)++;
  54   return true;
  55 }
  56
  57 static bool
  58 parse_uint (const char **pp, const char *end, unsigned int *pv)
  59 {
  60   char buf[32];
  61   unsigned int len = MIN (ARRAY_LENGTH (buf) - 1, (unsigned int) (end - *pp));
  62   strncpy (buf, *pp, len);
  63   buf[len] = '\0';
  64
  65   char *p = buf;
  66   char *pend = p;
  67   unsigned int v;
  68
  69   /* Intentionally use strtol instead of strtoul, such that
  70    * -1 turns into "big number"... */
  71   errno = 0;
  72   v = strtol (p, &pend, 0);
  73   if (errno || p == pend)
  74     return false;
  75
  76   *pv = v;
  77   *pp += pend - p;
  78   return true;
  79 }
  80
  81 static bool
  82 parse_bool (const char **pp, const char *end, unsigned int *pv)
  83 {
  84   parse_space (pp, end);
  85
  86   const char *p = *pp;
  87   while (*pp < end && ISALPHA(**pp))
  88     (*pp)++;
  89
  90   /* CSS allows on/off as aliases 1/0. */
  91   if (*pp - p == 2 || 0 == strncmp (p, "on", 2))
  92     *pv = 1;
  93   else if (*pp - p == 3 || 0 == strncmp (p, "off", 2))
  94     *pv = 0;
  95   else
  96     return false;
  97
  98   return true;
  99 }
 100
 101 static bool
 102 parse_feature_value_prefix (const char **pp, const char *end, hb_feature_t *feature)
 103 {
 104   if (parse_char (pp, end, '-'))
 105     feature->value = 0;
 106   else {
 107     parse_char (pp, end, '+');
 108     feature->value = 1;
 109   }
 110
 111   return true;
 112 }
 113
 114 static bool
 115 parse_feature_tag (const char **pp, const char *end, hb_feature_t *feature)
 116 {
 117   parse_space (pp, end);
 118
 119   char quote = 0;
 120
 121   if (*pp < end && (**pp == '\'' || **pp == '"'))
 122   {
 123     quote = **pp;
 124     (*pp)++;
 125   }
 126
 127   const char *p = *pp;
 128   while (*pp < end && ISALNUM(**pp))
 129     (*pp)++;
 130
 131   if (p == *pp || *pp - p > 4)
 132     return false;
 133
 134   feature->tag = hb_tag_from_string (p, *pp - p);
 135
 136   if (quote)
 137   {
 138     /* CSS expects exactly four bytes.  And we only allow quotations for
 139      * CSS compatibility.  So, enforce the length. */
 140      if (*pp - p != 4)
 141        return false;
 142     if (*pp == end || **pp != quote)
 143       return false;
 144     (*pp)++;
 145   }
 146
 147   return true;
 148 }
 149
 150 static bool
 151 parse_feature_indices (const char **pp, const char *end, hb_feature_t *feature)
 152 {
 153   parse_space (pp, end);
 154
 155   bool has_start;
 156
 157   feature->start = 0;
 158   feature->end = (unsigned int) -1;
 159
 160   if (!parse_char (pp, end, '['))
 161     return true;
 162
 163   has_start = parse_uint (pp, end, &feature->start);
 164
 165   if (parse_char (pp, end, ':')) {
 166     parse_uint (pp, end, &feature->end);
 167   } else {
 168     if (has_start)
 169       feature->end = feature->start + 1;
 170   }
 171
 172   return parse_char (pp, end, ']');
 173 }
 174
 175 static bool
 176 parse_feature_value_postfix (const char **pp, const char *end, hb_feature_t *feature)
 177 {
 178   bool had_equal = parse_char (pp, end, '=');
 179   bool had_value = parse_uint (pp, end, &feature->value) ||
 180                    parse_bool (pp, end, &feature->value);
 181   /* CSS doesn't use equal-sign between tag and value.
 182    * If there was an equal-sign, then there *must* be a value.
 183    * A value without an eqaul-sign is ok, but not required. */
 184   return !had_equal || had_value;
 185 }
 186
 187
 188 static bool
 189 parse_one_feature (const char **pp, const char *end, hb_feature_t *feature)
 190 {
 191   return parse_feature_value_prefix (pp, end, feature) &&
 192          parse_feature_tag (pp, end, feature) &&
 193          parse_feature_indices (pp, end, feature) &&
 194          parse_feature_value_postfix (pp, end, feature) &&
 195          parse_space (pp, end) &&
 196          *pp == end;
 197 }
 198
 199 /**
 200  * hb_feature_from_string:
 201  * @str: (array length=len):
 202  * @len:
 203  * @feature: (out) (optional):
 204  *
 205  *
 206  *
 207  * Return value:
 208  *
 209  * Since: 1.0
 210  **/
 211 hb_bool_t
 212 hb_feature_from_string (const char *str, int len,
 213                         hb_feature_t *feature)
 214 {
 215   hb_feature_t feat;
 216
 217   if (len < 0)
 218     len = strlen (str);
 219
 220   if (likely (parse_one_feature (&str, str + len, &feat)))
 221   {
 222     if (feature)
 223       *feature = feat;
 224     return true;
 225   }
 226
 227   if (feature)
 228     memset (feature, 0, sizeof (*feature));
 229   return false;
 230 }
 231
 232 /**
 233  * hb_feature_to_string:
 234  * @feature:
 235  * @buf: (array length=size):
 236  * @size:
 237  *
 238  *
 239  *
 240  * Since: 1.0
 241  **/
 242 void
 243 hb_feature_to_string (hb_feature_t *feature,
 244                       char *buf, unsigned int size)
 245 {
 246   if (unlikely (!size)) return;
 247
 248   char s[128];
 249   unsigned int len = 0;
 250   if (feature->value == 0)
 251     s[len++] = '-';
 252   hb_tag_to_string (feature->tag, s + len);
 253   len += 4;
 254   while (len && s[len - 1] == ' ')
 255     len--;
 256   if (feature->start != 0 || feature->end != (unsigned int) -1)
 257   {
 258     s[len++] = '[';
 259     if (feature->start)
 260       len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->start));
 261     if (feature->end != feature->start + 1) {
 262       s[len++] = ':';
 263       if (feature->end != (unsigned int) -1)
 264         len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->end));
 265     }
 266     s[len++] = ']';
 267   }
 268   if (feature->value > 1)
 269   {
 270     s[len++] = '=';
 271     len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->value));
 272   }
 273   assert (len < ARRAY_LENGTH (s));
 274   len = MIN (len, size - 1);
 275   memcpy (buf, s, len);
 276   buf[len] = '\0';
 277 }
 278
 279
 280 static const char **static_shaper_list;
 281
 282 #ifdef HB_USE_ATEXIT
 283 static
 284 void free_static_shaper_list (void)
 285 {
 286   free (static_shaper_list);
 287 }
 288 #endif
 289
 290 /**
 291  * hb_shape_list_shapers:
 292  *
 293  *
 294  *
 295  * Return value: (transfer none):
 296  *
 297  * Since: 1.0
 298  **/
 299 const char **
 300 hb_shape_list_shapers (void)
 301 {
 302 retry:
 303   const char **shaper_list = (const char **) hb_atomic_ptr_get (&static_shaper_list);
 304
 305   if (unlikely (!shaper_list))
 306   {
 307     /* Not found; allocate one. */
 308     shaper_list = (const char **) calloc (1 + HB_SHAPERS_COUNT, sizeof (const char *));
 309     if (unlikely (!shaper_list)) {
 310       static const char *nil_shaper_list[] = {NULL};
 311       return nil_shaper_list;
 312     }
 313
 314     const hb_shaper_pair_t *shapers = _hb_shapers_get ();
 315     unsigned int i;
 316     for (i = 0; i < HB_SHAPERS_COUNT; i++)
 317       shaper_list[i] = shapers[i].name;
 318     shaper_list[i] = NULL;
 319
 320     if (!hb_atomic_ptr_cmpexch (&static_shaper_list, NULL, shaper_list)) {
 321       free (shaper_list);
 322       goto retry;
 323     }
 324
 325 #ifdef HB_USE_ATEXIT
 326     atexit (free_static_shaper_list); /* First person registers atexit() callback. */
 327 #endif
 328   }
 329
 330   return shaper_list;
 331 }
 332
 333
 334 /**
 335  * hb_shape_full:
 336  * @font: a font.
 337  * @buffer: a buffer.
 338  * @features: (array length=num_features):
 339  * @num_features:
 340  * @shaper_list: (array zero-terminated=1):
 341  *
 342  *
 343  *
 344  * Return value:
 345  *
 346  * Since: 1.0
 347  **/
 348 hb_bool_t
 349 hb_shape_full (hb_font_t          *font,
 350                hb_buffer_t        *buffer,
 351                const hb_feature_t *features,
 352                unsigned int        num_features,
 353                const char * const *shaper_list)
 354 {
 355   if (unlikely (!buffer->len))
 356     return true;
 357
 358   assert (buffer->content_type == HB_BUFFER_CONTENT_TYPE_UNICODE);
 359
 360   hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props, features, num_features, shaper_list);
 361   hb_bool_t res = hb_shape_plan_execute (shape_plan, font, buffer, features, num_features);
 362   hb_shape_plan_destroy (shape_plan);
 363
 364   if (res)
 365     buffer->content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;
 366   return res;
 367 }
 368
 369 /**
 370  * hb_shape:
 371  * @font: a font.
 372  * @buffer: a buffer.
 373  * @features: (array length=num_features):
 374  * @num_features:
 375  *
 376  *
 377  *
 378  * Since: 1.0
 379  **/
 380 void
 381 hb_shape (hb_font_t           *font,
 382           hb_buffer_t         *buffer,
 383           const hb_feature_t  *features,
 384           unsigned int         num_features)
 385 {
 386   hb_shape_full (font, buffer, features, num_features, NULL);
 387 }