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1 /*
2  * Copyright © 2009  Red Hat, Inc.
3  * Copyright © 2011  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 #ifndef HB_FONT_HH
30 #define HB_FONT_HH
31 
32 #include "hb.hh"
33 
34 #include "hb-face.hh"
35 #include "hb-shaper.hh"
36 
37 
38 /*
39  * hb_font_funcs_t
40  */
41 
42 #define HB_FONT_FUNCS_IMPLEMENT_CALLBACKS \
43   HB_FONT_FUNC_IMPLEMENT (font_h_extents) \
44   HB_FONT_FUNC_IMPLEMENT (font_v_extents) \
45   HB_FONT_FUNC_IMPLEMENT (nominal_glyph) \
46   HB_FONT_FUNC_IMPLEMENT (nominal_glyphs) \
47   HB_FONT_FUNC_IMPLEMENT (variation_glyph) \
48   HB_FONT_FUNC_IMPLEMENT (glyph_h_advance) \
49   HB_FONT_FUNC_IMPLEMENT (glyph_v_advance) \
50   HB_FONT_FUNC_IMPLEMENT (glyph_h_advances) \
51   HB_FONT_FUNC_IMPLEMENT (glyph_v_advances) \
52   HB_FONT_FUNC_IMPLEMENT (glyph_h_origin) \
53   HB_FONT_FUNC_IMPLEMENT (glyph_v_origin) \
54   HB_FONT_FUNC_IMPLEMENT (glyph_h_kerning) \
55   HB_IF_NOT_DEPRECATED (HB_FONT_FUNC_IMPLEMENT (glyph_v_kerning)) \
56   HB_FONT_FUNC_IMPLEMENT (glyph_extents) \
57   HB_FONT_FUNC_IMPLEMENT (glyph_contour_point) \
58   HB_FONT_FUNC_IMPLEMENT (glyph_name) \
59   HB_FONT_FUNC_IMPLEMENT (glyph_from_name) \
60   /* ^--- Add new callbacks here */
61 
62 struct hb_font_funcs_t
63 {
64   hb_object_header_t header;
65 
66   struct {
67 #define HB_FONT_FUNC_IMPLEMENT(name) void *name;
68     HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
69 #undef HB_FONT_FUNC_IMPLEMENT
70   } user_data;
71 
72   struct {
73 #define HB_FONT_FUNC_IMPLEMENT(name) hb_destroy_func_t name;
74     HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
75 #undef HB_FONT_FUNC_IMPLEMENT
76   } destroy;
77 
78   /* Don't access these directly.  Call font->get_*() instead. */
79   union get_t {
80     struct get_funcs_t {
81 #define HB_FONT_FUNC_IMPLEMENT(name) hb_font_get_##name##_func_t name;
82       HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
83 #undef HB_FONT_FUNC_IMPLEMENT
84     } f;
85     void (*array[0
86 #define HB_FONT_FUNC_IMPLEMENT(name) +1
87       HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
88 #undef HB_FONT_FUNC_IMPLEMENT
89 		]) ();
90   } get;
91 };
92 DECLARE_NULL_INSTANCE (hb_font_funcs_t);
93 
94 
95 /*
96  * hb_font_t
97  */
98 
99 #define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INSTANTIATE_SHAPERS(shaper, font);
100 #include "hb-shaper-list.hh"
101 #undef HB_SHAPER_IMPLEMENT
102 
103 struct hb_font_t
104 {
105   hb_object_header_t header;
106 
107   hb_font_t *parent;
108   hb_face_t *face;
109 
110   int32_t x_scale;
111   int32_t y_scale;
112   int64_t x_mult;
113   int64_t y_mult;
114 
115   unsigned int x_ppem;
116   unsigned int y_ppem;
117 
118   float ptem;
119 
120   /* Font variation coordinates. */
121   unsigned int num_coords;
122   int *coords;
123   float *design_coords;
124 
125   hb_font_funcs_t   *klass;
126   void              *user_data;
127   hb_destroy_func_t  destroy;
128 
129   hb_shaper_object_dataset_t<hb_font_t> data; /* Various shaper data. */
130 
131 
132   /* Convert from font-space to user-space */
dir_multhb_font_t133   int64_t dir_mult (hb_direction_t direction)
134   { return HB_DIRECTION_IS_VERTICAL(direction) ? y_mult : x_mult; }
em_scale_xhb_font_t135   hb_position_t em_scale_x (int16_t v) { return em_mult (v, x_mult); }
em_scale_yhb_font_t136   hb_position_t em_scale_y (int16_t v) { return em_mult (v, y_mult); }
em_scalef_xhb_font_t137   hb_position_t em_scalef_x (float v) { return em_scalef (v, x_scale); }
em_scalef_yhb_font_t138   hb_position_t em_scalef_y (float v) { return em_scalef (v, y_scale); }
em_fscale_xhb_font_t139   float em_fscale_x (int16_t v) { return em_fscale (v, x_scale); }
em_fscale_yhb_font_t140   float em_fscale_y (int16_t v) { return em_fscale (v, y_scale); }
em_scale_dirhb_font_t141   hb_position_t em_scale_dir (int16_t v, hb_direction_t direction)
142   { return em_mult (v, dir_mult (direction)); }
143 
144   /* Convert from parent-font user-space to our user-space */
parent_scale_x_distancehb_font_t145   hb_position_t parent_scale_x_distance (hb_position_t v)
146   {
147     if (unlikely (parent && parent->x_scale != x_scale))
148       return (hb_position_t) (v * (int64_t) this->x_scale / this->parent->x_scale);
149     return v;
150   }
parent_scale_y_distancehb_font_t151   hb_position_t parent_scale_y_distance (hb_position_t v)
152   {
153     if (unlikely (parent && parent->y_scale != y_scale))
154       return (hb_position_t) (v * (int64_t) this->y_scale / this->parent->y_scale);
155     return v;
156   }
parent_scale_x_positionhb_font_t157   hb_position_t parent_scale_x_position (hb_position_t v)
158   { return parent_scale_x_distance (v); }
parent_scale_y_positionhb_font_t159   hb_position_t parent_scale_y_position (hb_position_t v)
160   { return parent_scale_y_distance (v); }
161 
parent_scale_distancehb_font_t162   void parent_scale_distance (hb_position_t *x, hb_position_t *y)
163   {
164     *x = parent_scale_x_distance (*x);
165     *y = parent_scale_y_distance (*y);
166   }
parent_scale_positionhb_font_t167   void parent_scale_position (hb_position_t *x, hb_position_t *y)
168   {
169     *x = parent_scale_x_position (*x);
170     *y = parent_scale_y_position (*y);
171   }
172 
173 
174   /* Public getters */
175 
176   HB_INTERNAL bool has_func (unsigned int i);
177   HB_INTERNAL bool has_func_set (unsigned int i);
178 
179   /* has_* ... */
180 #define HB_FONT_FUNC_IMPLEMENT(name) \
181   bool \
182   has_##name##_func () \
183   { \
184     hb_font_funcs_t *funcs = this->klass; \
185     unsigned int i = offsetof (hb_font_funcs_t::get_t::get_funcs_t, name) / sizeof (funcs->get.array[0]); \
186     return has_func (i); \
187   } \
188   bool \
189   has_##name##_func_set () \
190   { \
191     hb_font_funcs_t *funcs = this->klass; \
192     unsigned int i = offsetof (hb_font_funcs_t::get_t::get_funcs_t, name) / sizeof (funcs->get.array[0]); \
193     return has_func_set (i); \
194   }
195   HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
196 #undef HB_FONT_FUNC_IMPLEMENT
197 
get_font_h_extentshb_font_t198   hb_bool_t get_font_h_extents (hb_font_extents_t *extents)
199   {
200     memset (extents, 0, sizeof (*extents));
201     return klass->get.f.font_h_extents (this, user_data,
202 					extents,
203 					klass->user_data.font_h_extents);
204   }
get_font_v_extentshb_font_t205   hb_bool_t get_font_v_extents (hb_font_extents_t *extents)
206   {
207     memset (extents, 0, sizeof (*extents));
208     return klass->get.f.font_v_extents (this, user_data,
209 					extents,
210 					klass->user_data.font_v_extents);
211   }
212 
has_glyphhb_font_t213   bool has_glyph (hb_codepoint_t unicode)
214   {
215     hb_codepoint_t glyph;
216     return get_nominal_glyph (unicode, &glyph);
217   }
218 
get_nominal_glyphhb_font_t219   hb_bool_t get_nominal_glyph (hb_codepoint_t unicode,
220 			       hb_codepoint_t *glyph)
221   {
222     *glyph = 0;
223     return klass->get.f.nominal_glyph (this, user_data,
224 				       unicode, glyph,
225 				       klass->user_data.nominal_glyph);
226   }
get_nominal_glyphshb_font_t227   unsigned int get_nominal_glyphs (unsigned int count,
228 				   const hb_codepoint_t *first_unicode,
229 				   unsigned int unicode_stride,
230 				   hb_codepoint_t *first_glyph,
231 				   unsigned int glyph_stride)
232   {
233     return klass->get.f.nominal_glyphs (this, user_data,
234 					count,
235 					first_unicode, unicode_stride,
236 					first_glyph, glyph_stride,
237 					klass->user_data.nominal_glyphs);
238   }
239 
get_variation_glyphhb_font_t240   hb_bool_t get_variation_glyph (hb_codepoint_t unicode, hb_codepoint_t variation_selector,
241 				 hb_codepoint_t *glyph)
242   {
243     *glyph = 0;
244     return klass->get.f.variation_glyph (this, user_data,
245 					 unicode, variation_selector, glyph,
246 					 klass->user_data.variation_glyph);
247   }
248 
get_glyph_h_advancehb_font_t249   hb_position_t get_glyph_h_advance (hb_codepoint_t glyph)
250   {
251     return klass->get.f.glyph_h_advance (this, user_data,
252 					 glyph,
253 					 klass->user_data.glyph_h_advance);
254   }
255 
get_glyph_v_advancehb_font_t256   hb_position_t get_glyph_v_advance (hb_codepoint_t glyph)
257   {
258     return klass->get.f.glyph_v_advance (this, user_data,
259 					 glyph,
260 					 klass->user_data.glyph_v_advance);
261   }
262 
get_glyph_h_advanceshb_font_t263   void get_glyph_h_advances (unsigned int count,
264 			     const hb_codepoint_t *first_glyph,
265 			     unsigned int glyph_stride,
266 			     hb_position_t *first_advance,
267 			     unsigned int advance_stride)
268   {
269     return klass->get.f.glyph_h_advances (this, user_data,
270 					  count,
271 					  first_glyph, glyph_stride,
272 					  first_advance, advance_stride,
273 					  klass->user_data.glyph_h_advances);
274   }
275 
get_glyph_v_advanceshb_font_t276   void get_glyph_v_advances (unsigned int count,
277 			     const hb_codepoint_t *first_glyph,
278 			     unsigned int glyph_stride,
279 			     hb_position_t *first_advance,
280 			     unsigned int advance_stride)
281   {
282     return klass->get.f.glyph_v_advances (this, user_data,
283 					  count,
284 					  first_glyph, glyph_stride,
285 					  first_advance, advance_stride,
286 					  klass->user_data.glyph_v_advances);
287   }
288 
get_glyph_h_originhb_font_t289   hb_bool_t get_glyph_h_origin (hb_codepoint_t glyph,
290 				hb_position_t *x, hb_position_t *y)
291   {
292     *x = *y = 0;
293     return klass->get.f.glyph_h_origin (this, user_data,
294 					glyph, x, y,
295 					klass->user_data.glyph_h_origin);
296   }
297 
get_glyph_v_originhb_font_t298   hb_bool_t get_glyph_v_origin (hb_codepoint_t glyph,
299 				hb_position_t *x, hb_position_t *y)
300   {
301     *x = *y = 0;
302     return klass->get.f.glyph_v_origin (this, user_data,
303 					glyph, x, y,
304 					klass->user_data.glyph_v_origin);
305   }
306 
get_glyph_h_kerninghb_font_t307   hb_position_t get_glyph_h_kerning (hb_codepoint_t left_glyph,
308 				     hb_codepoint_t right_glyph)
309   {
310 #ifdef HB_DISABLE_DEPRECATED
311     return 0;
312 #else
313     return klass->get.f.glyph_h_kerning (this, user_data,
314 					 left_glyph, right_glyph,
315 					 klass->user_data.glyph_h_kerning);
316 #endif
317   }
318 
get_glyph_v_kerninghb_font_t319   hb_position_t get_glyph_v_kerning (hb_codepoint_t top_glyph,
320 				     hb_codepoint_t bottom_glyph)
321   {
322 #ifdef HB_DISABLE_DEPRECATED
323     return 0;
324 #else
325     return klass->get.f.glyph_v_kerning (this, user_data,
326 					 top_glyph, bottom_glyph,
327 					 klass->user_data.glyph_v_kerning);
328 #endif
329   }
330 
get_glyph_extentshb_font_t331   hb_bool_t get_glyph_extents (hb_codepoint_t glyph,
332 			       hb_glyph_extents_t *extents)
333   {
334     memset (extents, 0, sizeof (*extents));
335     return klass->get.f.glyph_extents (this, user_data,
336 				       glyph,
337 				       extents,
338 				       klass->user_data.glyph_extents);
339   }
340 
get_glyph_contour_pointhb_font_t341   hb_bool_t get_glyph_contour_point (hb_codepoint_t glyph, unsigned int point_index,
342 				     hb_position_t *x, hb_position_t *y)
343   {
344     *x = *y = 0;
345     return klass->get.f.glyph_contour_point (this, user_data,
346 					     glyph, point_index,
347 					     x, y,
348 					     klass->user_data.glyph_contour_point);
349   }
350 
get_glyph_namehb_font_t351   hb_bool_t get_glyph_name (hb_codepoint_t glyph,
352 			    char *name, unsigned int size)
353   {
354     if (size) *name = '\0';
355     return klass->get.f.glyph_name (this, user_data,
356 				    glyph,
357 				    name, size,
358 				    klass->user_data.glyph_name);
359   }
360 
get_glyph_from_namehb_font_t361   hb_bool_t get_glyph_from_name (const char *name, int len, /* -1 means nul-terminated */
362 				 hb_codepoint_t *glyph)
363   {
364     *glyph = 0;
365     if (len == -1) len = strlen (name);
366     return klass->get.f.glyph_from_name (this, user_data,
367 					 name, len,
368 					 glyph,
369 					 klass->user_data.glyph_from_name);
370   }
371 
372 
373   /* A bit higher-level, and with fallback */
374 
get_h_extents_with_fallbackhb_font_t375   void get_h_extents_with_fallback (hb_font_extents_t *extents)
376   {
377     if (!get_font_h_extents (extents))
378     {
379       extents->ascender = y_scale * .8;
380       extents->descender = extents->ascender - y_scale;
381       extents->line_gap = 0;
382     }
383   }
get_v_extents_with_fallbackhb_font_t384   void get_v_extents_with_fallback (hb_font_extents_t *extents)
385   {
386     if (!get_font_v_extents (extents))
387     {
388       extents->ascender = x_scale / 2;
389       extents->descender = extents->ascender - x_scale;
390       extents->line_gap = 0;
391     }
392   }
393 
get_extents_for_directionhb_font_t394   void get_extents_for_direction (hb_direction_t direction,
395 				  hb_font_extents_t *extents)
396   {
397     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
398       get_h_extents_with_fallback (extents);
399     else
400       get_v_extents_with_fallback (extents);
401   }
402 
get_glyph_advance_for_directionhb_font_t403   void get_glyph_advance_for_direction (hb_codepoint_t glyph,
404 					hb_direction_t direction,
405 					hb_position_t *x, hb_position_t *y)
406   {
407     *x = *y = 0;
408     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
409       *x = get_glyph_h_advance (glyph);
410     else
411       *y = get_glyph_v_advance (glyph);
412   }
get_glyph_advances_for_directionhb_font_t413   void get_glyph_advances_for_direction (hb_direction_t direction,
414 					 unsigned int count,
415 					 const hb_codepoint_t *first_glyph,
416 					 unsigned glyph_stride,
417 					 hb_position_t *first_advance,
418 					 unsigned advance_stride)
419   {
420     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
421       get_glyph_h_advances (count, first_glyph, glyph_stride, first_advance, advance_stride);
422     else
423       get_glyph_v_advances (count, first_glyph, glyph_stride, first_advance, advance_stride);
424   }
425 
guess_v_origin_minus_h_originhb_font_t426   void guess_v_origin_minus_h_origin (hb_codepoint_t glyph,
427 				      hb_position_t *x, hb_position_t *y)
428   {
429     *x = get_glyph_h_advance (glyph) / 2;
430 
431     /* TODO cache this somehow?! */
432     hb_font_extents_t extents;
433     get_h_extents_with_fallback (&extents);
434     *y = extents.ascender;
435   }
436 
get_glyph_h_origin_with_fallbackhb_font_t437   void get_glyph_h_origin_with_fallback (hb_codepoint_t glyph,
438 					 hb_position_t *x, hb_position_t *y)
439   {
440     if (!get_glyph_h_origin (glyph, x, y) &&
441 	 get_glyph_v_origin (glyph, x, y))
442     {
443       hb_position_t dx, dy;
444       guess_v_origin_minus_h_origin (glyph, &dx, &dy);
445       *x -= dx; *y -= dy;
446     }
447   }
get_glyph_v_origin_with_fallbackhb_font_t448   void get_glyph_v_origin_with_fallback (hb_codepoint_t glyph,
449 					 hb_position_t *x, hb_position_t *y)
450   {
451     if (!get_glyph_v_origin (glyph, x, y) &&
452 	 get_glyph_h_origin (glyph, x, y))
453     {
454       hb_position_t dx, dy;
455       guess_v_origin_minus_h_origin (glyph, &dx, &dy);
456       *x += dx; *y += dy;
457     }
458   }
459 
get_glyph_origin_for_directionhb_font_t460   void get_glyph_origin_for_direction (hb_codepoint_t glyph,
461 				       hb_direction_t direction,
462 				       hb_position_t *x, hb_position_t *y)
463   {
464     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
465       get_glyph_h_origin_with_fallback (glyph, x, y);
466     else
467       get_glyph_v_origin_with_fallback (glyph, x, y);
468   }
469 
add_glyph_h_originhb_font_t470   void add_glyph_h_origin (hb_codepoint_t glyph,
471 			   hb_position_t *x, hb_position_t *y)
472   {
473     hb_position_t origin_x, origin_y;
474 
475     get_glyph_h_origin_with_fallback (glyph, &origin_x, &origin_y);
476 
477     *x += origin_x;
478     *y += origin_y;
479   }
add_glyph_v_originhb_font_t480   void add_glyph_v_origin (hb_codepoint_t glyph,
481 			   hb_position_t *x, hb_position_t *y)
482   {
483     hb_position_t origin_x, origin_y;
484 
485     get_glyph_v_origin_with_fallback (glyph, &origin_x, &origin_y);
486 
487     *x += origin_x;
488     *y += origin_y;
489   }
add_glyph_origin_for_directionhb_font_t490   void add_glyph_origin_for_direction (hb_codepoint_t glyph,
491 				       hb_direction_t direction,
492 				       hb_position_t *x, hb_position_t *y)
493   {
494     hb_position_t origin_x, origin_y;
495 
496     get_glyph_origin_for_direction (glyph, direction, &origin_x, &origin_y);
497 
498     *x += origin_x;
499     *y += origin_y;
500   }
501 
subtract_glyph_h_originhb_font_t502   void subtract_glyph_h_origin (hb_codepoint_t glyph,
503 				hb_position_t *x, hb_position_t *y)
504   {
505     hb_position_t origin_x, origin_y;
506 
507     get_glyph_h_origin_with_fallback (glyph, &origin_x, &origin_y);
508 
509     *x -= origin_x;
510     *y -= origin_y;
511   }
subtract_glyph_v_originhb_font_t512   void subtract_glyph_v_origin (hb_codepoint_t glyph,
513 				hb_position_t *x, hb_position_t *y)
514   {
515     hb_position_t origin_x, origin_y;
516 
517     get_glyph_v_origin_with_fallback (glyph, &origin_x, &origin_y);
518 
519     *x -= origin_x;
520     *y -= origin_y;
521   }
subtract_glyph_origin_for_directionhb_font_t522   void subtract_glyph_origin_for_direction (hb_codepoint_t glyph,
523 					    hb_direction_t direction,
524 					    hb_position_t *x, hb_position_t *y)
525   {
526     hb_position_t origin_x, origin_y;
527 
528     get_glyph_origin_for_direction (glyph, direction, &origin_x, &origin_y);
529 
530     *x -= origin_x;
531     *y -= origin_y;
532   }
533 
get_glyph_kerning_for_directionhb_font_t534   void get_glyph_kerning_for_direction (hb_codepoint_t first_glyph, hb_codepoint_t second_glyph,
535 					hb_direction_t direction,
536 					hb_position_t *x, hb_position_t *y)
537   {
538     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction))) {
539       *y = 0;
540       *x = get_glyph_h_kerning (first_glyph, second_glyph);
541     } else {
542       *x = 0;
543       *y = get_glyph_v_kerning (first_glyph, second_glyph);
544     }
545   }
546 
get_glyph_extents_for_originhb_font_t547   hb_bool_t get_glyph_extents_for_origin (hb_codepoint_t glyph,
548 					  hb_direction_t direction,
549 					  hb_glyph_extents_t *extents)
550   {
551     hb_bool_t ret = get_glyph_extents (glyph, extents);
552 
553     if (ret)
554       subtract_glyph_origin_for_direction (glyph, direction, &extents->x_bearing, &extents->y_bearing);
555 
556     return ret;
557   }
558 
get_glyph_contour_point_for_originhb_font_t559   hb_bool_t get_glyph_contour_point_for_origin (hb_codepoint_t glyph, unsigned int point_index,
560 						hb_direction_t direction,
561 						hb_position_t *x, hb_position_t *y)
562   {
563     hb_bool_t ret = get_glyph_contour_point (glyph, point_index, x, y);
564 
565     if (ret)
566       subtract_glyph_origin_for_direction (glyph, direction, x, y);
567 
568     return ret;
569   }
570 
571   /* Generates gidDDD if glyph has no name. */
572   void
glyph_to_stringhb_font_t573   glyph_to_string (hb_codepoint_t glyph,
574 		   char *s, unsigned int size)
575   {
576     if (get_glyph_name (glyph, s, size)) return;
577 
578     if (size && snprintf (s, size, "gid%u", glyph) < 0)
579       *s = '\0';
580   }
581 
582   /* Parses gidDDD and uniUUUU strings automatically. */
583   hb_bool_t
glyph_from_stringhb_font_t584   glyph_from_string (const char *s, int len, /* -1 means nul-terminated */
585 		     hb_codepoint_t *glyph)
586   {
587     if (get_glyph_from_name (s, len, glyph)) return true;
588 
589     if (len == -1) len = strlen (s);
590 
591     /* Straight glyph index. */
592     if (hb_codepoint_parse (s, len, 10, glyph))
593       return true;
594 
595     if (len > 3)
596     {
597       /* gidDDD syntax for glyph indices. */
598       if (0 == strncmp (s, "gid", 3) &&
599 	  hb_codepoint_parse (s + 3, len - 3, 10, glyph))
600 	return true;
601 
602       /* uniUUUU and other Unicode character indices. */
603       hb_codepoint_t unichar;
604       if (0 == strncmp (s, "uni", 3) &&
605 	  hb_codepoint_parse (s + 3, len - 3, 16, &unichar) &&
606 	  get_nominal_glyph (unichar, glyph))
607 	return true;
608     }
609 
610     return false;
611   }
612 
mults_changedhb_font_t613   void mults_changed ()
614   {
615     signed upem = face->get_upem ();
616     x_mult = ((int64_t) x_scale << 16) / upem;
617     y_mult = ((int64_t) y_scale << 16) / upem;
618   }
619 
em_multhb_font_t620   hb_position_t em_mult (int16_t v, int64_t mult)
621   {
622     return (hb_position_t) ((v * mult) >> 16);
623   }
em_scalefhb_font_t624   hb_position_t em_scalef (float v, int scale)
625   { return (hb_position_t) roundf (v * scale / face->get_upem ()); }
em_fscalehb_font_t626   float em_fscale (int16_t v, int scale)
627   { return (float) v * scale / face->get_upem (); }
628 };
629 DECLARE_NULL_INSTANCE (hb_font_t);
630 
631 
632 #endif /* HB_FONT_HH */
633