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.hh"
30
31 #include "hb-shaper.hh"
32 #include "hb-shape-plan.hh"
33 #include "hb-buffer.hh"
34 #include "hb-font.hh"
35 #include "hb-machinery.hh"
36
37
38 #ifndef HB_NO_SHAPER
39
40 /**
41 * SECTION:hb-shape
42 * @title: hb-shape
43 * @short_description: Conversion of text strings into positioned glyphs
44 * @include: hb.h
45 *
46 * Shaping is the central operation of HarfBuzz. Shaping operates on buffers,
47 * which are sequences of Unicode characters that use the same font and have
48 * the same text direction, script, and language. After shaping the buffer
49 * contains the output glyphs and their positions.
50 **/
51
52
53 static inline void free_static_shaper_list ();
54
55 static const char * const nil_shaper_list[] = {nullptr};
56
57 static struct hb_shaper_list_lazy_loader_t : hb_lazy_loader_t<const char *,
58 hb_shaper_list_lazy_loader_t>
59 {
createhb_shaper_list_lazy_loader_t60 static const char ** create ()
61 {
62 const char **shaper_list = (const char **) hb_calloc (1 + HB_SHAPERS_COUNT, sizeof (const char *));
63 if (unlikely (!shaper_list))
64 return nullptr;
65
66 const hb_shaper_entry_t *shapers = _hb_shapers_get ();
67 unsigned int i;
68 for (i = 0; i < HB_SHAPERS_COUNT; i++)
69 shaper_list[i] = shapers[i].name;
70 shaper_list[i] = nullptr;
71
72 hb_atexit (free_static_shaper_list);
73
74 return shaper_list;
75 }
destroyhb_shaper_list_lazy_loader_t76 static void destroy (const char **l)
77 { hb_free (l); }
get_nullhb_shaper_list_lazy_loader_t78 static const char * const * get_null ()
79 { return nil_shaper_list; }
80 } static_shaper_list;
81
82 static inline
free_static_shaper_list()83 void free_static_shaper_list ()
84 {
85 static_shaper_list.free_instance ();
86 }
87
88
89 /**
90 * hb_shape_list_shapers:
91 *
92 * Retrieves the list of shapers supported by HarfBuzz.
93 *
94 * Return value: (transfer none) (array zero-terminated=1): an array of
95 * constant strings
96 *
97 * Since: 0.9.2
98 **/
99 const char **
hb_shape_list_shapers()100 hb_shape_list_shapers ()
101 {
102 return static_shaper_list.get_unconst ();
103 }
104
105
106 /**
107 * hb_shape_full:
108 * @font: an #hb_font_t to use for shaping
109 * @buffer: an #hb_buffer_t to shape
110 * @features: (array length=num_features) (nullable): an array of user
111 * specified #hb_feature_t or `NULL`
112 * @num_features: the length of @features array
113 * @shaper_list: (array zero-terminated=1) (nullable): a `NULL`-terminated
114 * array of shapers to use or `NULL`
115 *
116 * See hb_shape() for details. If @shaper_list is not `NULL`, the specified
117 * shapers will be used in the given order, otherwise the default shapers list
118 * will be used.
119 *
120 * Return value: false if all shapers failed, true otherwise
121 *
122 * Since: 0.9.2
123 **/
124 hb_bool_t
hb_shape_full(hb_font_t * font,hb_buffer_t * buffer,const hb_feature_t * features,unsigned int num_features,const char * const * shaper_list)125 hb_shape_full (hb_font_t *font,
126 hb_buffer_t *buffer,
127 const hb_feature_t *features,
128 unsigned int num_features,
129 const char * const *shaper_list)
130 {
131 if (unlikely (!buffer->len))
132 return true;
133
134 buffer->enter ();
135
136 hb_buffer_t *text_buffer = nullptr;
137 if (buffer->flags & HB_BUFFER_FLAG_VERIFY)
138 {
139 text_buffer = hb_buffer_create ();
140 hb_buffer_append (text_buffer, buffer, 0, -1);
141 }
142
143 hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached2 (font->face, &buffer->props,
144 features, num_features,
145 font->coords, font->num_coords,
146 shaper_list);
147
148 hb_bool_t res = hb_shape_plan_execute (shape_plan, font, buffer, features, num_features);
149
150 if (buffer->max_ops <= 0)
151 buffer->shaping_failed = true;
152
153 hb_shape_plan_destroy (shape_plan);
154
155 if (text_buffer)
156 {
157 if (res && buffer->successful && !buffer->shaping_failed
158 && text_buffer->successful
159 && !buffer->verify (text_buffer,
160 font,
161 features,
162 num_features,
163 shaper_list))
164 res = false;
165 hb_buffer_destroy (text_buffer);
166 }
167
168 buffer->leave ();
169
170 return res;
171 }
172
173 /**
174 * hb_shape:
175 * @font: an #hb_font_t to use for shaping
176 * @buffer: an #hb_buffer_t to shape
177 * @features: (array length=num_features) (nullable): an array of user
178 * specified #hb_feature_t or `NULL`
179 * @num_features: the length of @features array
180 *
181 * Shapes @buffer using @font turning its Unicode characters content to
182 * positioned glyphs. If @features is not `NULL`, it will be used to control the
183 * features applied during shaping. If two @features have the same tag but
184 * overlapping ranges the value of the feature with the higher index takes
185 * precedence.
186 *
187 * Since: 0.9.2
188 **/
189 void
hb_shape(hb_font_t * font,hb_buffer_t * buffer,const hb_feature_t * features,unsigned int num_features)190 hb_shape (hb_font_t *font,
191 hb_buffer_t *buffer,
192 const hb_feature_t *features,
193 unsigned int num_features)
194 {
195 hb_shape_full (font, buffer, features, num_features, nullptr);
196 }
197
198
199 #ifdef HB_EXPERIMENTAL_API
200
201 static float
buffer_advance(hb_buffer_t * buffer)202 buffer_advance (hb_buffer_t *buffer)
203 {
204 float a = 0;
205 auto *pos = buffer->pos;
206 unsigned count = buffer->len;
207 if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
208 for (unsigned i = 0; i < count; i++)
209 a += pos[i].x_advance;
210 else
211 for (unsigned i = 0; i < count; i++)
212 a += pos[i].y_advance;
213 return a;
214 }
215
216 static void
reset_buffer(hb_buffer_t * buffer,hb_array_t<const hb_glyph_info_t> text)217 reset_buffer (hb_buffer_t *buffer,
218 hb_array_t<const hb_glyph_info_t> text)
219 {
220 assert (buffer->ensure (text.length));
221 buffer->have_positions = false;
222 buffer->len = text.length;
223 hb_memcpy (buffer->info, text.arrayZ, text.length * sizeof (buffer->info[0]));
224 hb_buffer_set_content_type (buffer, HB_BUFFER_CONTENT_TYPE_UNICODE);
225 }
226
227 /**
228 * hb_shape_justify:
229 * @font: a mutable #hb_font_t to use for shaping
230 * @buffer: an #hb_buffer_t to shape
231 * @features: (array length=num_features) (nullable): an array of user
232 * specified #hb_feature_t or `NULL`
233 * @num_features: the length of @features array
234 * @shaper_list: (array zero-terminated=1) (nullable): a `NULL`-terminated
235 * array of shapers to use or `NULL`
236 * @min_target_advance: Minimum advance width/height to aim for.
237 * @max_target_advance: Maximum advance width/height to aim for.
238 * @advance: (inout): Input/output advance width/height of the buffer.
239 * @var_tag: (out): Variation-axis tag used for justification.
240 * @var_value: (out): Variation-axis value used to reach target justification.
241 *
242 * See hb_shape_full() for basic details. If @shaper_list is not `NULL`, the specified
243 * shapers will be used in the given order, otherwise the default shapers list
244 * will be used.
245 *
246 * In addition, justify the shaping results such that the shaping results reach
247 * the target advance width/height, depending on the buffer direction.
248 *
249 * If the advance of the buffer shaped with hb_shape_full() is already known,
250 * put that in *advance. Otherwise set *advance to zero.
251 *
252 * This API is currently experimental and will probably change in the future.
253 *
254 * Return value: false if all shapers failed, true otherwise
255 *
256 * XSince: EXPERIMENTAL
257 **/
258 hb_bool_t
hb_shape_justify(hb_font_t * font,hb_buffer_t * buffer,const hb_feature_t * features,unsigned int num_features,const char * const * shaper_list,float min_target_advance,float max_target_advance,float * advance,hb_tag_t * var_tag,float * var_value)259 hb_shape_justify (hb_font_t *font,
260 hb_buffer_t *buffer,
261 const hb_feature_t *features,
262 unsigned int num_features,
263 const char * const *shaper_list,
264 float min_target_advance,
265 float max_target_advance,
266 float *advance, /* IN/OUT */
267 hb_tag_t *var_tag, /* OUT */
268 float *var_value /* OUT */)
269 {
270 // TODO Negative font scales?
271
272 /* If default advance already matches target, nothing to do. Shape and return. */
273 if (min_target_advance <= *advance && *advance <= max_target_advance)
274 {
275 *var_tag = HB_TAG_NONE;
276 *var_value = 0.0f;
277 return hb_shape_full (font, buffer,
278 features, num_features,
279 shaper_list);
280 }
281
282 hb_face_t *face = font->face;
283
284 /* Choose variation tag to use for justification. */
285
286 hb_tag_t tag = HB_TAG_NONE;
287 hb_ot_var_axis_info_t axis_info;
288
289 hb_tag_t tags[] =
290 {
291 HB_TAG ('j','s','t','f'),
292 HB_TAG ('w','d','t','h'),
293 };
294 for (unsigned i = 0; i < ARRAY_LENGTH (tags); i++)
295 if (hb_ot_var_find_axis_info (face, tags[i], &axis_info))
296 {
297 tag = *var_tag = tags[i];
298 break;
299 }
300
301 /* If no suitable variation axis found, can't justify. Just shape and return. */
302 if (!tag)
303 {
304 *var_tag = HB_TAG_NONE;
305 *var_value = 0.0f;
306 if (hb_shape_full (font, buffer,
307 features, num_features,
308 shaper_list))
309 {
310 *advance = buffer_advance (buffer);
311 return true;
312 }
313 else
314 return false;
315 }
316
317 /* Copy buffer text as we need it so we can shape multiple times. */
318 unsigned text_len = buffer->len;
319 auto *text_info = (hb_glyph_info_t *) hb_malloc (text_len * sizeof (buffer->info[0]));
320 if (unlikely (text_len && !text_info))
321 return false;
322 hb_memcpy (text_info, buffer->info, text_len * sizeof (buffer->info[0]));
323 auto text = hb_array<const hb_glyph_info_t> (text_info, text_len);
324
325 /* If default advance was not provided to us, calculate it. */
326 if (!*advance)
327 {
328 hb_font_set_variation (font, tag, axis_info.default_value);
329 if (!hb_shape_full (font, buffer,
330 features, num_features,
331 shaper_list))
332 return false;
333 *advance = buffer_advance (buffer);
334 }
335
336 /* If default advance already matches target, nothing to do. Shape and return.
337 * Do this again, in case advance was just calculated.
338 */
339 if (min_target_advance <= *advance && *advance <= max_target_advance)
340 {
341 *var_tag = HB_TAG_NONE;
342 *var_value = 0.0f;
343 return true;
344 }
345
346 /* Prepare for running the solver. */
347 double a, b, ya, yb;
348 if (*advance < min_target_advance)
349 {
350 /* Need to expand. */
351 ya = (double) *advance;
352 a = (double) axis_info.default_value;
353 b = (double) axis_info.max_value;
354
355 /* Shape buffer for maximum expansion to use as other
356 * starting point for the solver. */
357 hb_font_set_variation (font, tag, (float) b);
358 reset_buffer (buffer, text);
359 if (!hb_shape_full (font, buffer,
360 features, num_features,
361 shaper_list))
362 return false;
363 yb = (double) buffer_advance (buffer);
364 /* If the maximum expansion is less than max target,
365 * there's nothing to solve for. Just return it. */
366 if (yb <= (double) max_target_advance)
367 {
368 *var_value = (float) b;
369 *advance = (float) yb;
370 return true;
371 }
372 }
373 else
374 {
375 /* Need to shrink. */
376 yb = (double) *advance;
377 a = (double) axis_info.min_value;
378 b = (double) axis_info.default_value;
379
380 /* Shape buffer for maximum shrinkate to use as other
381 * starting point for the solver. */
382 hb_font_set_variation (font, tag, (float) a);
383 reset_buffer (buffer, text);
384 if (!hb_shape_full (font, buffer,
385 features, num_features,
386 shaper_list))
387 return false;
388 ya = (double) buffer_advance (buffer);
389 /* If the maximum shrinkate is more than min target,
390 * there's nothing to solve for. Just return it. */
391 if (ya >= (double) min_target_advance)
392 {
393 *var_value = (float) a;
394 *advance = (float) ya;
395 return true;
396 }
397 }
398
399 /* Run the solver to find a var axis value that hits
400 * the desired width. */
401
402 double epsilon = (b - a) / (1<<14);
403 bool failed = false;
404
405 auto f = [&] (double x)
406 {
407 hb_font_set_variation (font, tag, (float) x);
408 reset_buffer (buffer, text);
409 if (unlikely (!hb_shape_full (font, buffer,
410 features, num_features,
411 shaper_list)))
412 {
413 failed = true;
414 return (double) min_target_advance;
415 }
416
417 double w = (double) buffer_advance (buffer);
418 DEBUG_MSG (JUSTIFY, nullptr, "Trying '%c%c%c%c' axis parameter %f. Advance %g. Target: min %g max %g",
419 HB_UNTAG (tag), x, w,
420 (double) min_target_advance, (double) max_target_advance);
421 return w;
422 };
423
424 double y = 0;
425 double itp = solve_itp (f,
426 a, b,
427 epsilon,
428 (double) min_target_advance, (double) max_target_advance,
429 ya, yb, y);
430
431 hb_free (text_info);
432
433 if (failed)
434 return false;
435
436 *var_value = (float) itp;
437 *advance = (float) y;
438
439 return true;
440 }
441
442 #endif
443
444
445 #endif
446