src/hb-font.hh

   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
 124   hb_font_funcs_t   *klass;
 125   void              *user_data;
 126   hb_destroy_func_t  destroy;
 127
 128   hb_shaper_object_dataset_t<hb_font_t> data; /* Various shaper data. */
 129
 130
 131   /* Convert from font-space to user-space */
 132   int64_t dir_mult (hb_direction_t direction)
 133   { return HB_DIRECTION_IS_VERTICAL(direction) ? y_mult : x_mult; }
 134   hb_position_t em_scale_x (int16_t v) { return em_mult (v, x_mult); }
 135   hb_position_t em_scale_y (int16_t v) { return em_mult (v, y_mult); }
 136   hb_position_t em_scalef_x (float v) { return em_scalef (v, x_scale); }
 137   hb_position_t em_scalef_y (float v) { return em_scalef (v, y_scale); }
 138   float em_fscale_x (int16_t v) { return em_fscale (v, x_scale); }
 139   float em_fscale_y (int16_t v) { return em_fscale (v, y_scale); }
 140   hb_position_t em_scale_dir (int16_t v, hb_direction_t direction)
 141   { return em_mult (v, dir_mult (direction)); }
 142
 143   /* Convert from parent-font user-space to our user-space */
 144   hb_position_t parent_scale_x_distance (hb_position_t v)
 145   {
 146     if (unlikely (parent && parent->x_scale != x_scale))
 147       return (hb_position_t) (v * (int64_t) this->x_scale / this->parent->x_scale);
 148     return v;
 149   }
 150   hb_position_t parent_scale_y_distance (hb_position_t v)
 151   {
 152     if (unlikely (parent && parent->y_scale != y_scale))
 153       return (hb_position_t) (v * (int64_t) this->y_scale / this->parent->y_scale);
 154     return v;
 155   }
 156   hb_position_t parent_scale_x_position (hb_position_t v)
 157   { return parent_scale_x_distance (v); }
 158   hb_position_t parent_scale_y_position (hb_position_t v)
 159   { return parent_scale_y_distance (v); }
 160
 161   void parent_scale_distance (hb_position_t *x, hb_position_t *y)
 162   {
 163     *x = parent_scale_x_distance (*x);
 164     *y = parent_scale_y_distance (*y);
 165   }
 166   void parent_scale_position (hb_position_t *x, hb_position_t *y)
 167   {
 168     *x = parent_scale_x_position (*x);
 169     *y = parent_scale_y_position (*y);
 170   }
 171
 172
 173   /* Public getters */
 174
 175   HB_INTERNAL bool has_func (unsigned int i);
 176   HB_INTERNAL bool has_func_set (unsigned int i);
 177
 178   /* has_* ... */
 179 #define HB_FONT_FUNC_IMPLEMENT(name) \
 180   bool \
 181   has_##name##_func () \
 182   { \
 183     hb_font_funcs_t *funcs = this->klass; \
 184     unsigned int i = offsetof (hb_font_funcs_t::get_t::get_funcs_t, name) / sizeof (funcs->get.array[0]); \
 185     return has_func (i); \
 186   } \
 187   bool \
 188   has_##name##_func_set () \
 189   { \
 190     hb_font_funcs_t *funcs = this->klass; \
 191     unsigned int i = offsetof (hb_font_funcs_t::get_t::get_funcs_t, name) / sizeof (funcs->get.array[0]); \
 192     return has_func_set (i); \
 193   }
 194   HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
 195 #undef HB_FONT_FUNC_IMPLEMENT
 196
 197   hb_bool_t get_font_h_extents (hb_font_extents_t *extents)
 198   {
 199     memset (extents, 0, sizeof (*extents));
 200     return klass->get.f.font_h_extents (this, user_data,
 201                                         extents,
 202                                         klass->user_data.font_h_extents);
 203   }
 204   hb_bool_t get_font_v_extents (hb_font_extents_t *extents)
 205   {
 206     memset (extents, 0, sizeof (*extents));
 207     return klass->get.f.font_v_extents (this, user_data,
 208                                         extents,
 209                                         klass->user_data.font_v_extents);
 210   }
 211
 212   bool has_glyph (hb_codepoint_t unicode)
 213   {
 214     hb_codepoint_t glyph;
 215     return get_nominal_glyph (unicode, &glyph);
 216   }
 217
 218   hb_bool_t get_nominal_glyph (hb_codepoint_t unicode,
 219                                hb_codepoint_t *glyph)
 220   {
 221     *glyph = 0;
 222     return klass->get.f.nominal_glyph (this, user_data,
 223                                        unicode, glyph,
 224                                        klass->user_data.nominal_glyph);
 225   }
 226   unsigned int get_nominal_glyphs (unsigned int count,
 227                                    const hb_codepoint_t *first_unicode,
 228                                    unsigned int unicode_stride,
 229                                    hb_codepoint_t *first_glyph,
 230                                    unsigned int glyph_stride)
 231   {
 232     return klass->get.f.nominal_glyphs (this, user_data,
 233                                         count,
 234                                         first_unicode, unicode_stride,
 235                                         first_glyph, glyph_stride,
 236                                         klass->user_data.nominal_glyphs);
 237   }
 238
 239   hb_bool_t get_variation_glyph (hb_codepoint_t unicode, hb_codepoint_t variation_selector,
 240                                  hb_codepoint_t *glyph)
 241   {
 242     *glyph = 0;
 243     return klass->get.f.variation_glyph (this, user_data,
 244                                          unicode, variation_selector, glyph,
 245                                          klass->user_data.variation_glyph);
 246   }
 247
 248   hb_position_t get_glyph_h_advance (hb_codepoint_t glyph)
 249   {
 250     return klass->get.f.glyph_h_advance (this, user_data,
 251                                          glyph,
 252                                          klass->user_data.glyph_h_advance);
 253   }
 254
 255   hb_position_t get_glyph_v_advance (hb_codepoint_t glyph)
 256   {
 257     return klass->get.f.glyph_v_advance (this, user_data,
 258                                          glyph,
 259                                          klass->user_data.glyph_v_advance);
 260   }
 261
 262   void get_glyph_h_advances (unsigned int count,
 263                              const hb_codepoint_t *first_glyph,
 264                              unsigned int glyph_stride,
 265                              hb_position_t *first_advance,
 266                              unsigned int advance_stride)
 267   {
 268     return klass->get.f.glyph_h_advances (this, user_data,
 269                                           count,
 270                                           first_glyph, glyph_stride,
 271                                           first_advance, advance_stride,
 272                                           klass->user_data.glyph_h_advances);
 273   }
 274
 275   void get_glyph_v_advances (unsigned int count,
 276                              const hb_codepoint_t *first_glyph,
 277                              unsigned int glyph_stride,
 278                              hb_position_t *first_advance,
 279                              unsigned int advance_stride)
 280   {
 281     return klass->get.f.glyph_v_advances (this, user_data,
 282                                           count,
 283                                           first_glyph, glyph_stride,
 284                                           first_advance, advance_stride,
 285                                           klass->user_data.glyph_v_advances);
 286   }
 287
 288   hb_bool_t get_glyph_h_origin (hb_codepoint_t glyph,
 289                                 hb_position_t *x, hb_position_t *y)
 290   {
 291     *x = *y = 0;
 292     return klass->get.f.glyph_h_origin (this, user_data,
 293                                         glyph, x, y,
 294                                         klass->user_data.glyph_h_origin);
 295   }
 296
 297   hb_bool_t get_glyph_v_origin (hb_codepoint_t glyph,
 298                                 hb_position_t *x, hb_position_t *y)
 299   {
 300     *x = *y = 0;
 301     return klass->get.f.glyph_v_origin (this, user_data,
 302                                         glyph, x, y,
 303                                         klass->user_data.glyph_v_origin);
 304   }
 305
 306   hb_position_t get_glyph_h_kerning (hb_codepoint_t left_glyph,
 307                                      hb_codepoint_t right_glyph)
 308   {
 309 #ifdef HB_DISABLE_DEPRECATED
 310     return 0;
 311 #else
 312     return klass->get.f.glyph_h_kerning (this, user_data,
 313                                          left_glyph, right_glyph,
 314                                          klass->user_data.glyph_h_kerning);
 315 #endif
 316   }
 317
 318   hb_position_t get_glyph_v_kerning (hb_codepoint_t top_glyph,
 319                                      hb_codepoint_t bottom_glyph)
 320   {
 321 #ifdef HB_DISABLE_DEPRECATED
 322     return 0;
 323 #else
 324     return klass->get.f.glyph_v_kerning (this, user_data,
 325                                          top_glyph, bottom_glyph,
 326                                          klass->user_data.glyph_v_kerning);
 327 #endif
 328   }
 329
 330   hb_bool_t get_glyph_extents (hb_codepoint_t glyph,
 331                                hb_glyph_extents_t *extents)
 332   {
 333     memset (extents, 0, sizeof (*extents));
 334     return klass->get.f.glyph_extents (this, user_data,
 335                                        glyph,
 336                                        extents,
 337                                        klass->user_data.glyph_extents);
 338   }
 339
 340   hb_bool_t get_glyph_contour_point (hb_codepoint_t glyph, unsigned int point_index,
 341                                             hb_position_t *x, hb_position_t *y)
 342   {
 343     *x = *y = 0;
 344     return klass->get.f.glyph_contour_point (this, user_data,
 345                                              glyph, point_index,
 346                                              x, y,
 347                                              klass->user_data.glyph_contour_point);
 348   }
 349
 350   hb_bool_t get_glyph_name (hb_codepoint_t glyph,
 351                             char *name, unsigned int size)
 352   {
 353     if (size) *name = '\0';
 354     return klass->get.f.glyph_name (this, user_data,
 355                                     glyph,
 356                                     name, size,
 357                                     klass->user_data.glyph_name);
 358   }
 359
 360   hb_bool_t get_glyph_from_name (const char *name, int len, /* -1 means nul-terminated */
 361                                  hb_codepoint_t *glyph)
 362   {
 363     *glyph = 0;
 364     if (len == -1) len = strlen (name);
 365     return klass->get.f.glyph_from_name (this, user_data,
 366                                          name, len,
 367                                          glyph,
 368                                          klass->user_data.glyph_from_name);
 369   }
 370
 371
 372   /* A bit higher-level, and with fallback */
 373
 374   void get_h_extents_with_fallback (hb_font_extents_t *extents)
 375   {
 376     if (!get_font_h_extents (extents))
 377     {
 378       extents->ascender = y_scale * .8;
 379       extents->descender = extents->ascender - y_scale;
 380       extents->line_gap = 0;
 381     }
 382   }
 383   void get_v_extents_with_fallback (hb_font_extents_t *extents)
 384   {
 385     if (!get_font_v_extents (extents))
 386     {
 387       extents->ascender = x_scale / 2;
 388       extents->descender = extents->ascender - x_scale;
 389       extents->line_gap = 0;
 390     }
 391   }
 392
 393   void get_extents_for_direction (hb_direction_t direction,
 394                                   hb_font_extents_t *extents)
 395   {
 396     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
 397       get_h_extents_with_fallback (extents);
 398     else
 399       get_v_extents_with_fallback (extents);
 400   }
 401
 402   void get_glyph_advance_for_direction (hb_codepoint_t glyph,
 403                                         hb_direction_t direction,
 404                                         hb_position_t *x, hb_position_t *y)
 405   {
 406     *x = *y = 0;
 407     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
 408       *x = get_glyph_h_advance (glyph);
 409     else
 410       *y = get_glyph_v_advance (glyph);
 411   }
 412   void get_glyph_advances_for_direction (hb_direction_t direction,
 413                                          unsigned int count,
 414                                          const hb_codepoint_t *first_glyph,
 415                                          unsigned glyph_stride,
 416                                          hb_position_t *first_advance,
 417                                          unsigned advance_stride)
 418   {
 419     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
 420       get_glyph_h_advances (count, first_glyph, glyph_stride, first_advance, advance_stride);
 421     else
 422       get_glyph_v_advances (count, first_glyph, glyph_stride, first_advance, advance_stride);
 423   }
 424
 425   void guess_v_origin_minus_h_origin (hb_codepoint_t glyph,
 426                                       hb_position_t *x, hb_position_t *y)
 427   {
 428     *x = get_glyph_h_advance (glyph) / 2;
 429
 430     /* TODO cache this somehow?! */
 431     hb_font_extents_t extents;
 432     get_h_extents_with_fallback (&extents);
 433     *y = extents.ascender;
 434   }
 435
 436   void get_glyph_h_origin_with_fallback (hb_codepoint_t glyph,
 437                                          hb_position_t *x, hb_position_t *y)
 438   {
 439     if (!get_glyph_h_origin (glyph, x, y) &&
 440          get_glyph_v_origin (glyph, x, y))
 441     {
 442       hb_position_t dx, dy;
 443       guess_v_origin_minus_h_origin (glyph, &dx, &dy);
 444       *x -= dx; *y -= dy;
 445     }
 446   }
 447   void get_glyph_v_origin_with_fallback (hb_codepoint_t glyph,
 448                                          hb_position_t *x, hb_position_t *y)
 449   {
 450     if (!get_glyph_v_origin (glyph, x, y) &&
 451          get_glyph_h_origin (glyph, x, y))
 452     {
 453       hb_position_t dx, dy;
 454       guess_v_origin_minus_h_origin (glyph, &dx, &dy);
 455       *x += dx; *y += dy;
 456     }
 457   }
 458
 459   void get_glyph_origin_for_direction (hb_codepoint_t glyph,
 460                                        hb_direction_t direction,
 461                                        hb_position_t *x, hb_position_t *y)
 462   {
 463     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction)))
 464       get_glyph_h_origin_with_fallback (glyph, x, y);
 465     else
 466       get_glyph_v_origin_with_fallback (glyph, x, y);
 467   }
 468
 469   void add_glyph_h_origin (hb_codepoint_t glyph,
 470                            hb_position_t *x, hb_position_t *y)
 471   {
 472     hb_position_t origin_x, origin_y;
 473
 474     get_glyph_h_origin_with_fallback (glyph, &origin_x, &origin_y);
 475
 476     *x += origin_x;
 477     *y += origin_y;
 478   }
 479   void add_glyph_v_origin (hb_codepoint_t glyph,
 480                            hb_position_t *x, hb_position_t *y)
 481   {
 482     hb_position_t origin_x, origin_y;
 483
 484     get_glyph_v_origin_with_fallback (glyph, &origin_x, &origin_y);
 485
 486     *x += origin_x;
 487     *y += origin_y;
 488   }
 489   void add_glyph_origin_for_direction (hb_codepoint_t glyph,
 490                                        hb_direction_t direction,
 491                                        hb_position_t *x, hb_position_t *y)
 492   {
 493     hb_position_t origin_x, origin_y;
 494
 495     get_glyph_origin_for_direction (glyph, direction, &origin_x, &origin_y);
 496
 497     *x += origin_x;
 498     *y += origin_y;
 499   }
 500
 501   void subtract_glyph_h_origin (hb_codepoint_t glyph,
 502                                 hb_position_t *x, hb_position_t *y)
 503   {
 504     hb_position_t origin_x, origin_y;
 505
 506     get_glyph_h_origin_with_fallback (glyph, &origin_x, &origin_y);
 507
 508     *x -= origin_x;
 509     *y -= origin_y;
 510   }
 511   void subtract_glyph_v_origin (hb_codepoint_t glyph,
 512                                 hb_position_t *x, hb_position_t *y)
 513   {
 514     hb_position_t origin_x, origin_y;
 515
 516     get_glyph_v_origin_with_fallback (glyph, &origin_x, &origin_y);
 517
 518     *x -= origin_x;
 519     *y -= origin_y;
 520   }
 521   void subtract_glyph_origin_for_direction (hb_codepoint_t glyph,
 522                                             hb_direction_t direction,
 523                                             hb_position_t *x, hb_position_t *y)
 524   {
 525     hb_position_t origin_x, origin_y;
 526
 527     get_glyph_origin_for_direction (glyph, direction, &origin_x, &origin_y);
 528
 529     *x -= origin_x;
 530     *y -= origin_y;
 531   }
 532
 533   void get_glyph_kerning_for_direction (hb_codepoint_t first_glyph, hb_codepoint_t second_glyph,
 534                                         hb_direction_t direction,
 535                                         hb_position_t *x, hb_position_t *y)
 536   {
 537     if (likely (HB_DIRECTION_IS_HORIZONTAL (direction))) {
 538       *y = 0;
 539       *x = get_glyph_h_kerning (first_glyph, second_glyph);
 540     } else {
 541       *x = 0;
 542       *y = get_glyph_v_kerning (first_glyph, second_glyph);
 543     }
 544   }
 545
 546   hb_bool_t get_glyph_extents_for_origin (hb_codepoint_t glyph,
 547                                           hb_direction_t direction,
 548                                           hb_glyph_extents_t *extents)
 549   {
 550     hb_bool_t ret = get_glyph_extents (glyph, extents);
 551
 552     if (ret)
 553       subtract_glyph_origin_for_direction (glyph, direction, &extents->x_bearing, &extents->y_bearing);
 554
 555     return ret;
 556   }
 557
 558   hb_bool_t get_glyph_contour_point_for_origin (hb_codepoint_t glyph, unsigned int point_index,
 559                                                 hb_direction_t direction,
 560                                                 hb_position_t *x, hb_position_t *y)
 561   {
 562     hb_bool_t ret = get_glyph_contour_point (glyph, point_index, x, y);
 563
 564     if (ret)
 565       subtract_glyph_origin_for_direction (glyph, direction, x, y);
 566
 567     return ret;
 568   }
 569
 570   /* Generates gidDDD if glyph has no name. */
 571   void
 572   glyph_to_string (hb_codepoint_t glyph,
 573                    char *s, unsigned int size)
 574   {
 575     if (get_glyph_name (glyph, s, size)) return;
 576
 577     if (size && snprintf (s, size, "gid%u", glyph) < 0)
 578       *s = '\0';
 579   }
 580
 581   /* Parses gidDDD and uniUUUU strings automatically. */
 582   hb_bool_t
 583   glyph_from_string (const char *s, int len, /* -1 means nul-terminated */
 584                      hb_codepoint_t *glyph)
 585   {
 586     if (get_glyph_from_name (s, len, glyph)) return true;
 587
 588     if (len == -1) len = strlen (s);
 589
 590     /* Straight glyph index. */
 591     if (hb_codepoint_parse (s, len, 10, glyph))
 592       return true;
 593
 594     if (len > 3)
 595     {
 596       /* gidDDD syntax for glyph indices. */
 597       if (0 == strncmp (s, "gid", 3) &&
 598           hb_codepoint_parse (s + 3, len - 3, 10, glyph))
 599         return true;
 600
 601       /* uniUUUU and other Unicode character indices. */
 602       hb_codepoint_t unichar;
 603       if (0 == strncmp (s, "uni", 3) &&
 604           hb_codepoint_parse (s + 3, len - 3, 16, &unichar) &&
 605           get_nominal_glyph (unichar, glyph))
 606         return true;
 607     }
 608
 609     return false;
 610   }
 611
 612   void mults_changed ()
 613   {
 614     signed upem = face->get_upem ();
 615     x_mult = ((int64_t) x_scale << 16) / upem;
 616     y_mult = ((int64_t) y_scale << 16) / upem;
 617   }
 618
 619   hb_position_t em_mult (int16_t v, int64_t mult)
 620   {
 621     return (hb_position_t) ((v * mult) >> 16);
 622   }
 623   hb_position_t em_scalef (float v, int scale)
 624   { return (hb_position_t) roundf (v * scale / face->get_upem ()); }
 625   float em_fscale (int16_t v, int scale)
 626   { return (float) v * scale / face->get_upem (); }
 627 };
 628 DECLARE_NULL_INSTANCE (hb_font_t);
 629
 630
 631 #endif /* HB_FONT_HH */