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 * SECTION:hb-shape
38 * @title: Shaping
39 * @short_description: Conversion of text strings into positioned glyphs
40 * @include: hb.h
41 *
42 * Shaping is the central operation of HarfBuzz. Shaping operates on buffers,
43 * which are sequences of Unicode characters that use the same font and have
44 * the same text direction, script and language. After shaping the buffer
45 * contains the output glyphs and their positions.
46 **/
47
48 static bool
49 parse_space (const char **pp, const char *end)
50 {
51 while (*pp < end && ISSPACE (**pp))
52 (*pp)++;
53 return true;
54 }
55
56 static bool
57 parse_char (const char **pp, const char *end, char c)
58 {
59 parse_space (pp, end);
60
61 if (*pp == end || **pp != c)
62 return false;
63
64 (*pp)++;
65 return true;
66 }
67
68 static bool
69 parse_uint (const char **pp, const char *end, unsigned int *pv)
70 {
71 char buf[32];
72 unsigned int len = MIN (ARRAY_LENGTH (buf) - 1, (unsigned int) (end - *pp));
73 strncpy (buf, *pp, len);
74 buf[len] = '\0';
75
76 char *p = buf;
77 char *pend = p;
78 unsigned int v;
79
80 /* Intentionally use strtol instead of strtoul, such that
81 * -1 turns into "big number"... */
82 errno = 0;
83 v = strtol (p, &pend, 0);
84 if (errno || p == pend)
85 return false;
86
87 *pv = v;
88 *pp += pend - p;
89 return true;
90 }
91
92 static bool
93 parse_bool (const char **pp, const char *end, unsigned int *pv)
94 {
95 parse_space (pp, end);
96
97 const char *p = *pp;
98 while (*pp < end && ISALPHA(**pp))
99 (*pp)++;
100
101 /* CSS allows on/off as aliases 1/0. */
102 if (*pp - p == 2 || 0 == strncmp (p, "on", 2))
103 *pv = 1;
104 else if (*pp - p == 3 || 0 == strncmp (p, "off", 2))
105 *pv = 0;
106 else
107 return false;
108
109 return true;
110 }
111
112 static bool
113 parse_feature_value_prefix (const char **pp, const char *end, hb_feature_t *feature)
114 {
115 if (parse_char (pp, end, '-'))
116 feature->value = 0;
117 else {
118 parse_char (pp, end, '+');
119 feature->value = 1;
120 }
121
122 return true;
123 }
124
125 static bool
126 parse_feature_tag (const char **pp, const char *end, hb_feature_t *feature)
127 {
128 parse_space (pp, end);
129
130 char quote = 0;
131
132 if (*pp < end && (**pp == '\'' || **pp == '"'))
133 {
134 quote = **pp;
135 (*pp)++;
136 }
137
138 const char *p = *pp;
139 while (*pp < end && ISALNUM(**pp))
140 (*pp)++;
141
142 if (p == *pp || *pp - p > 4)
143 return false;
144
145 feature->tag = hb_tag_from_string (p, *pp - p);
146
147 if (quote)
148 {
149 /* CSS expects exactly four bytes. And we only allow quotations for
150 * CSS compatibility. So, enforce the length. */
151 if (*pp - p != 4)
152 return false;
153 if (*pp == end || **pp != quote)
154 return false;
155 (*pp)++;
156 }
157
158 return true;
159 }
160
161 static bool
162 parse_feature_indices (const char **pp, const char *end, hb_feature_t *feature)
163 {
164 parse_space (pp, end);
165
166 bool has_start;
167
168 feature->start = 0;
169 feature->end = (unsigned int) -1;
170
171 if (!parse_char (pp, end, '['))
172 return true;
173
174 has_start = parse_uint (pp, end, &feature->start);
175
176 if (parse_char (pp, end, ':')) {
177 parse_uint (pp, end, &feature->end);
178 } else {
179 if (has_start)
180 feature->end = feature->start + 1;
181 }
182
183 return parse_char (pp, end, ']');
184 }
185
186 static bool
187 parse_feature_value_postfix (const char **pp, const char *end, hb_feature_t *feature)
188 {
189 bool had_equal = parse_char (pp, end, '=');
190 bool had_value = parse_uint (pp, end, &feature->value) ||
191 parse_bool (pp, end, &feature->value);
192 /* CSS doesn't use equal-sign between tag and value.
193 * If there was an equal-sign, then there *must* be a value.
194 * A value without an eqaul-sign is ok, but not required. */
195 return !had_equal || had_value;
196 }
197
198
199 static bool
200 parse_one_feature (const char **pp, const char *end, hb_feature_t *feature)
201 {
202 return parse_feature_value_prefix (pp, end, feature) &&
203 parse_feature_tag (pp, end, feature) &&
204 parse_feature_indices (pp, end, feature) &&
205 parse_feature_value_postfix (pp, end, feature) &&
206 parse_space (pp, end) &&
207 *pp == end;
208 }
209
210 /**
211 * hb_feature_from_string:
212 * @str: (array length=len) (element-type uint8_t): a string to parse
213 * @len: length of @str, or -1 if string is nul-terminated
214 * @feature: (out): the #hb_feature_t to initialize with the parsed values
215 *
216 * Parses a string into a #hb_feature_t. If @len is -1 then @str is
217 * %NULL-terminated.
218 *
219 * Return value: %TRUE if @str is successfully parsed, %FALSE otherwise
220 *
221 * Since: 0.9.5
222 **/
223 hb_bool_t
224 hb_feature_from_string (const char *str, int len,
225 hb_feature_t *feature)
226 {
227 hb_feature_t feat;
228
229 if (len < 0)
230 len = strlen (str);
231
232 if (likely (parse_one_feature (&str, str + len, &feat)))
233 {
234 if (feature)
235 *feature = feat;
236 return true;
237 }
238
239 if (feature)
240 memset (feature, 0, sizeof (*feature));
241 return false;
242 }
243
244 /**
245 * hb_feature_to_string:
246 * @feature: an #hb_feature_t to convert
247 * @buf: (array length=size) (out): output string
248 * @size: the allocated size of @buf
249 *
250 * Converts a #hb_feature_t into a %NULL-terminated string in the format
251 * understood by hb_feature_from_string(). The client in responsible for
252 * allocating big enough size for @buf, 128 bytes is more than enough.
253 *
254 * Since: 0.9.5
255 **/
256 void
257 hb_feature_to_string (hb_feature_t *feature,
258 char *buf, unsigned int size)
259 {
260 if (unlikely (!size)) return;
261
262 char s[128];
263 unsigned int len = 0;
264 if (feature->value == 0)
265 s[len++] = '-';
266 hb_tag_to_string (feature->tag, s + len);
267 len += 4;
268 while (len && s[len - 1] == ' ')
269 len--;
270 if (feature->start != 0 || feature->end != (unsigned int) -1)
271 {
272 s[len++] = '[';
273 if (feature->start)
274 len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->start));
275 if (feature->end != feature->start + 1) {
276 s[len++] = ':';
277 if (feature->end != (unsigned int) -1)
278 len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->end));
279 }
280 s[len++] = ']';
281 }
282 if (feature->value > 1)
283 {
284 s[len++] = '=';
285 len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->value));
286 }
287 assert (len < ARRAY_LENGTH (s));
288 len = MIN (len, size - 1);
289 memcpy (buf, s, len);
290 buf[len] = '\0';
291 }
292
293
294 static const char **static_shaper_list;
295
296 #ifdef HB_USE_ATEXIT
297 static
298 void free_static_shaper_list (void)
299 {
300 free (static_shaper_list);
301 }
302 #endif
303
304 /**
305 * hb_shape_list_shapers:
306 *
307 * Retrieves the list of shapers supported by HarfBuzz.
308 *
309 * Return value: (transfer none) (array zero-terminated=1): an array of
310 * constant strings
311 *
312 * Since: 0.9.2
313 **/
314 const char **
315 hb_shape_list_shapers (void)
316 {
317 retry:
318 const char **shaper_list = (const char **) hb_atomic_ptr_get (&static_shaper_list);
319
320 if (unlikely (!shaper_list))
321 {
322 /* Not found; allocate one. */
323 shaper_list = (const char **) calloc (1 + HB_SHAPERS_COUNT, sizeof (const char *));
324 if (unlikely (!shaper_list)) {
325 static const char *nil_shaper_list[] = {NULL};
326 return nil_shaper_list;
327 }
328
329 const hb_shaper_pair_t *shapers = _hb_shapers_get ();
330 unsigned int i;
331 for (i = 0; i < HB_SHAPERS_COUNT; i++)
332 shaper_list[i] = shapers[i].name;
333 shaper_list[i] = NULL;
334
335 if (!hb_atomic_ptr_cmpexch (&static_shaper_list, NULL, shaper_list)) {
336 free (shaper_list);
337 goto retry;
338 }
339
340 #ifdef HB_USE_ATEXIT
341 atexit (free_static_shaper_list); /* First person registers atexit() callback. */
342 #endif
343 }
344
345 return shaper_list;
346 }
347
348
349 /**
350 * hb_shape_full:
351 * @font: an #hb_font_t to use for shaping
352 * @buffer: an #hb_buffer_t to shape
353 * @features: (array length=num_features) (allow-none): an array of user
354 * specified #hb_feature_t or %NULL
355 * @num_features: the length of @features array
356 * @shaper_list: (array zero-terminated=1) (allow-none): a %NULL-terminated
357 * array of shapers to use or %NULL
358 *
359 * See hb_shape() for details. If @shaper_list is not %NULL, the specified
360 * shapers will be used in the given order, otherwise the default shapers list
361 * will be used.
362 *
363 * Return value: %FALSE if all shapers failed, %TRUE otherwise
364 *
365 * Since: 0.9.2
366 **/
367 hb_bool_t
368 hb_shape_full (hb_font_t *font,
369 hb_buffer_t *buffer,
370 const hb_feature_t *features,
371 unsigned int num_features,
372 const char * const *shaper_list)
373 {
374 hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props, features, num_features, shaper_list);
375 hb_bool_t res = hb_shape_plan_execute (shape_plan, font, buffer, features, num_features);
376 hb_shape_plan_destroy (shape_plan);
377
378 if (res)
379 buffer->content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;
380 return res;
381 }
382
383 /**
384 * hb_shape:
385 * @font: an #hb_font_t to use for shaping
386 * @buffer: an #hb_buffer_t to shape
387 * @features: (array length=num_features) (allow-none): an array of user
388 * specified #hb_feature_t or %NULL
389 * @num_features: the length of @features array
390 *
391 * Shapes @buffer using @font turning its Unicode characters content to
392 * positioned glyphs. If @features is not %NULL, it will be used to control the
393 * features applied during shaping.
394 *
395 * Return value: %FALSE if all shapers failed, %TRUE otherwise
396 *
397 * Since: 0.9.2
398 **/
399 void
400 hb_shape (hb_font_t *font,
401 hb_buffer_t *buffer,
402 const hb_feature_t *features,
403 unsigned int num_features)
404 {
405 hb_shape_full (font, buffer, features, num_features, NULL);
406 }