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
48static bool
49parse_space (const char **pp, const char *end)
50{
51  while (*pp < end && ISSPACE (**pp))
52    (*pp)++;
53  return true;
54}
55
56static bool
57parse_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
68static bool
69parse_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
92static bool
93parse_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
112static bool
113parse_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
125static bool
126parse_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
161static bool
162parse_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
186static bool
187parse_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
199static bool
200parse_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 %NULL terminated
214 * @feature: (out): the #hb_feature_t to initialize with the parsed values
215 *
216 * Parses a string into a #hb_feature_t.
217 *
218 * TODO: document the syntax here.
219 *
220 * Return value:
221 * %true if @str is successfully parsed, %false otherwise.
222 *
223 * Since: 0.9.5
224 **/
225hb_bool_t
226hb_feature_from_string (const char *str, int len,
227			hb_feature_t *feature)
228{
229  hb_feature_t feat;
230
231  if (len < 0)
232    len = strlen (str);
233
234  if (likely (parse_one_feature (&str, str + len, &feat)))
235  {
236    if (feature)
237      *feature = feat;
238    return true;
239  }
240
241  if (feature)
242    memset (feature, 0, sizeof (*feature));
243  return false;
244}
245
246/**
247 * hb_feature_to_string:
248 * @feature: an #hb_feature_t to convert
249 * @buf: (array length=size) (out): output string
250 * @size: the allocated size of @buf
251 *
252 * Converts a #hb_feature_t into a %NULL-terminated string in the format
253 * understood by hb_feature_from_string(). The client in responsible for
254 * allocating big enough size for @buf, 128 bytes is more than enough.
255 *
256 * Since: 0.9.5
257 **/
258void
259hb_feature_to_string (hb_feature_t *feature,
260		      char *buf, unsigned int size)
261{
262  if (unlikely (!size)) return;
263
264  char s[128];
265  unsigned int len = 0;
266  if (feature->value == 0)
267    s[len++] = '-';
268  hb_tag_to_string (feature->tag, s + len);
269  len += 4;
270  while (len && s[len - 1] == ' ')
271    len--;
272  if (feature->start != 0 || feature->end != (unsigned int) -1)
273  {
274    s[len++] = '[';
275    if (feature->start)
276      len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->start));
277    if (feature->end != feature->start + 1) {
278      s[len++] = ':';
279      if (feature->end != (unsigned int) -1)
280	len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->end));
281    }
282    s[len++] = ']';
283  }
284  if (feature->value > 1)
285  {
286    s[len++] = '=';
287    len += MAX (0, snprintf (s + len, ARRAY_LENGTH (s) - len, "%u", feature->value));
288  }
289  assert (len < ARRAY_LENGTH (s));
290  len = MIN (len, size - 1);
291  memcpy (buf, s, len);
292  buf[len] = '\0';
293}
294
295
296static const char **static_shaper_list;
297
298#ifdef HB_USE_ATEXIT
299static
300void free_static_shaper_list (void)
301{
302  free (static_shaper_list);
303}
304#endif
305
306/**
307 * hb_shape_list_shapers:
308 *
309 * Retrieves the list of shapers supported by HarfBuzz.
310 *
311 * Return value: (transfer none) (array zero-terminated=1): an array of
312 *    constant strings
313 *
314 * Since: 0.9.2
315 **/
316const char **
317hb_shape_list_shapers (void)
318{
319retry:
320  const char **shaper_list = (const char **) hb_atomic_ptr_get (&static_shaper_list);
321
322  if (unlikely (!shaper_list))
323  {
324    /* Not found; allocate one. */
325    shaper_list = (const char **) calloc (1 + HB_SHAPERS_COUNT, sizeof (const char *));
326    if (unlikely (!shaper_list)) {
327      static const char *nil_shaper_list[] = {NULL};
328      return nil_shaper_list;
329    }
330
331    const hb_shaper_pair_t *shapers = _hb_shapers_get ();
332    unsigned int i;
333    for (i = 0; i < HB_SHAPERS_COUNT; i++)
334      shaper_list[i] = shapers[i].name;
335    shaper_list[i] = NULL;
336
337    if (!hb_atomic_ptr_cmpexch (&static_shaper_list, NULL, shaper_list)) {
338      free (shaper_list);
339      goto retry;
340    }
341
342#ifdef HB_USE_ATEXIT
343    atexit (free_static_shaper_list); /* First person registers atexit() callback. */
344#endif
345  }
346
347  return shaper_list;
348}
349
350
351/**
352 * hb_shape_full:
353 * @font: an #hb_font_t to use for shaping
354 * @buffer: an #hb_buffer_t to shape
355 * @features: (array length=num_features) (allow-none): an array of user
356 *    specified #hb_feature_t or %NULL
357 * @num_features: the length of @features array
358 * @shaper_list: (array zero-terminated=1) (allow-none): a %NULL-terminated
359 *    array of shapers to use or %NULL
360 *
361 * See hb_shape() for details. If @shaper_list is not %NULL, the specified
362 * shapers will be used in the given order, otherwise the default shapers list
363 * will be used.
364 *
365 * Return value: %FALSE if all shapers failed, %TRUE otherwise
366 *
367 * Since: 0.9.2
368 **/
369hb_bool_t
370hb_shape_full (hb_font_t          *font,
371	       hb_buffer_t        *buffer,
372	       const hb_feature_t *features,
373	       unsigned int        num_features,
374	       const char * const *shaper_list)
375{
376  hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props, features, num_features, shaper_list);
377  hb_bool_t res = hb_shape_plan_execute (shape_plan, font, buffer, features, num_features);
378  hb_shape_plan_destroy (shape_plan);
379
380  if (res)
381    buffer->content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;
382  return res;
383}
384
385/**
386 * hb_shape:
387 * @font: an #hb_font_t to use for shaping
388 * @buffer: an #hb_buffer_t to shape
389 * @features: (array length=num_features) (allow-none): an array of user
390 *    specified #hb_feature_t or %NULL
391 * @num_features: the length of @features array
392 *
393 * Shapes @buffer using @font turning its Unicode characters content to
394 * positioned glyphs. If @features is not %NULL, it will be used to control the
395 * features applied during shaping.
396 *
397 * Return value: %FALSE if all shapers failed, %TRUE otherwise
398 *
399 * Since: 0.9.2
400 **/
401void
402hb_shape (hb_font_t           *font,
403	  hb_buffer_t         *buffer,
404	  const hb_feature_t  *features,
405	  unsigned int         num_features)
406{
407  hb_shape_full (font, buffer, features, num_features, NULL);
408}
409