gfx/harfbuzz/src/hb-ot-metrics.cc

   1 /*
   2  * Copyright © 2018-2019  Ebrahim Byagowi
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  */
  24
  25 #include "hb.hh"
  26
  27 #include "hb-ot-var-mvar-table.hh"
  28 #include "hb-ot-gasp-table.hh" // Just so we compile it; unused otherwise.
  29 #include "hb-ot-os2-table.hh"
  30 #include "hb-ot-post-table.hh"
  31 #include "hb-ot-hhea-table.hh"
  32 #include "hb-ot-metrics.hh"
  33 #include "hb-ot-face.hh"
  34
  35
  36 /**
  37  * SECTION:hb-ot-metrics
  38  * @title: hb-ot-metrics
  39  * @short_description: OpenType Metrics
  40  * @include: hb-ot.h
  41  *
  42  * Functions for fetching metrics from fonts.
  43  **/
  44
  45 static float
  46 _fix_ascender_descender (float value, hb_ot_metrics_tag_t metrics_tag)
  47 {
  48   if (metrics_tag == HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER ||
  49       metrics_tag == HB_OT_METRICS_TAG_VERTICAL_ASCENDER)
  50     return fabs ((double) value);
  51   if (metrics_tag == HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER ||
  52       metrics_tag == HB_OT_METRICS_TAG_VERTICAL_DESCENDER)
  53     return -fabs ((double) value);
  54   return value;
  55 }
  56
  57 /* The common part of _get_position logic needed on hb-ot-font and here
  58    to be able to have slim builds without the not always needed parts */
  59 bool
  60 _hb_ot_metrics_get_position_common (hb_font_t           *font,
  61                                     hb_ot_metrics_tag_t  metrics_tag,
  62                                     hb_position_t       *position     /* OUT.  May be NULL. */)
  63 {
  64   hb_face_t *face = font->face;
  65   switch ((unsigned) metrics_tag)
  66   {
  67 #ifndef HB_NO_VAR
  68 #define GET_VAR face->table.MVAR->get_var (metrics_tag, font->coords, font->num_coords)
  69 #else
  70 #define GET_VAR .0f
  71 #endif
  72 #define GET_METRIC_X(TABLE, ATTR) \
  73   (face->table.TABLE->has_data () && \
  74     ((void) (position && (*position = font->em_scalef_x (_fix_ascender_descender ( \
  75       face->table.TABLE->ATTR + GET_VAR, metrics_tag)))), true))
  76 #define GET_METRIC_Y(TABLE, ATTR) \
  77   (face->table.TABLE->has_data () && \
  78     ((void) (position && (*position = font->em_scalef_y (_fix_ascender_descender ( \
  79       face->table.TABLE->ATTR + GET_VAR, metrics_tag)))), true))
  80
  81   case HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER:
  82     return (face->table.OS2->use_typo_metrics () && GET_METRIC_Y (OS2, sTypoAscender)) ||
  83            GET_METRIC_Y (hhea, ascender);
  84   case HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER:
  85     return (face->table.OS2->use_typo_metrics () && GET_METRIC_Y (OS2, sTypoDescender)) ||
  86            GET_METRIC_Y (hhea, descender);
  87   case HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP:
  88     return (face->table.OS2->use_typo_metrics () && GET_METRIC_Y (OS2, sTypoLineGap)) ||
  89            GET_METRIC_Y (hhea, lineGap);
  90
  91 #ifndef HB_NO_VERTICAL
  92   case HB_OT_METRICS_TAG_VERTICAL_ASCENDER:  return GET_METRIC_X (vhea, ascender);
  93   case HB_OT_METRICS_TAG_VERTICAL_DESCENDER: return GET_METRIC_X (vhea, descender);
  94   case HB_OT_METRICS_TAG_VERTICAL_LINE_GAP:  return GET_METRIC_X (vhea, lineGap);
  95 #endif
  96
  97 #undef GET_METRIC_Y
  98 #undef GET_METRIC_X
  99 #undef GET_VAR
 100   default:                               assert (0); return false;
 101   }
 102 }
 103
 104 #ifndef HB_NO_METRICS
 105
 106 #if 0
 107 static bool
 108 _get_gasp (hb_face_t *face, float *result, hb_ot_metrics_tag_t metrics_tag)
 109 {
 110   const OT::GaspRange& range = face->table.gasp->get_gasp_range (metrics_tag - HB_TAG ('g','s','p','0'));
 111   if (&range == &Null (OT::GaspRange)) return false;
 112   if (result) *result = range.rangeMaxPPEM + font->face->table.MVAR->get_var (metrics_tag, font->coords, font->num_coords);
 113   return true;
 114 }
 115 #endif
 116
 117 /* Private tags for https://github.com/harfbuzz/harfbuzz/issues/1866 */
 118 #define _HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER_OS2   HB_TAG ('O','a','s','c')
 119 #define _HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER_HHEA  HB_TAG ('H','a','s','c')
 120 #define _HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER_OS2  HB_TAG ('O','d','s','c')
 121 #define _HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER_HHEA HB_TAG ('H','d','s','c')
 122 #define _HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP_OS2   HB_TAG ('O','l','g','p')
 123 #define _HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP_HHEA  HB_TAG ('H','l','g','p')
 124
 125 /**
 126  * hb_ot_metrics_get_position:
 127  * @font: an #hb_font_t object.
 128  * @metrics_tag: tag of metrics value you like to fetch.
 129  * @position: (out) (optional): result of metrics value from the font.
 130  *
 131  * Fetches metrics value corresponding to @metrics_tag from @font.
 132  *
 133  * Returns: Whether found the requested metrics in the font.
 134  * Since: 2.6.0
 135  **/
 136 hb_bool_t
 137 hb_ot_metrics_get_position (hb_font_t           *font,
 138                             hb_ot_metrics_tag_t  metrics_tag,
 139                             hb_position_t       *position     /* OUT.  May be NULL. */)
 140 {
 141   hb_face_t *face = font->face;
 142   switch ((unsigned) metrics_tag)
 143   {
 144   case HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER:
 145   case HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER:
 146   case HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP:
 147   case HB_OT_METRICS_TAG_VERTICAL_ASCENDER:
 148   case HB_OT_METRICS_TAG_VERTICAL_DESCENDER:
 149   case HB_OT_METRICS_TAG_VERTICAL_LINE_GAP:           return _hb_ot_metrics_get_position_common (font, metrics_tag, position);
 150 #ifndef HB_NO_VAR
 151 #define GET_VAR hb_ot_metrics_get_variation (font, metrics_tag)
 152 #else
 153 #define GET_VAR 0
 154 #endif
 155 #define GET_METRIC_X(TABLE, ATTR) \
 156   (face->table.TABLE->has_data () && \
 157     ((void) (position && (*position = font->em_scalef_x (face->table.TABLE->ATTR + GET_VAR))), true))
 158 #define GET_METRIC_Y(TABLE, ATTR) \
 159   (face->table.TABLE->has_data () && \
 160     ((void) (position && (*position = font->em_scalef_y (face->table.TABLE->ATTR + GET_VAR))), true))
 161   case HB_OT_METRICS_TAG_HORIZONTAL_CLIPPING_ASCENT:  return GET_METRIC_Y (OS2, usWinAscent);
 162   case HB_OT_METRICS_TAG_HORIZONTAL_CLIPPING_DESCENT: return GET_METRIC_Y (OS2, usWinDescent);
 163
 164   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_RISE:
 165   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_RUN:
 166   {
 167     unsigned mult = 1u;
 168
 169     if (font->slant)
 170     {
 171       unsigned rise = face->table.hhea->caretSlopeRise;
 172       unsigned upem = face->get_upem ();
 173       mult = (rise && rise < upem) ? hb_min (upem / rise, 256u) : 1u;
 174     }
 175
 176     if (metrics_tag == HB_OT_METRICS_TAG_HORIZONTAL_CARET_RISE)
 177     {
 178       bool ret = GET_METRIC_Y (hhea, caretSlopeRise);
 179
 180       if (position)
 181         *position *= mult;
 182
 183       return ret;
 184     }
 185     else
 186     {
 187       hb_position_t rise = 0;
 188
 189       if (font->slant && position && GET_METRIC_Y (hhea, caretSlopeRise))
 190         rise = *position;
 191
 192       bool ret = GET_METRIC_X (hhea, caretSlopeRun);
 193
 194       if (position)
 195       {
 196         *position *= mult;
 197
 198         if (font->slant)
 199           *position += roundf (mult * font->slant_xy * rise);
 200       }
 201
 202       return ret;
 203     }
 204   }
 205   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_OFFSET:     return GET_METRIC_X (hhea, caretOffset);
 206
 207 #ifndef HB_NO_VERTICAL
 208   case HB_OT_METRICS_TAG_VERTICAL_CARET_RISE:         return GET_METRIC_X (vhea, caretSlopeRise);
 209   case HB_OT_METRICS_TAG_VERTICAL_CARET_RUN:          return GET_METRIC_Y (vhea, caretSlopeRun);
 210   case HB_OT_METRICS_TAG_VERTICAL_CARET_OFFSET:       return GET_METRIC_Y (vhea, caretOffset);
 211 #endif
 212   case HB_OT_METRICS_TAG_X_HEIGHT:                    return GET_METRIC_Y (OS2->v2 (), sxHeight);
 213   case HB_OT_METRICS_TAG_CAP_HEIGHT:                  return GET_METRIC_Y (OS2->v2 (), sCapHeight);
 214   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_X_SIZE:         return GET_METRIC_X (OS2, ySubscriptXSize);
 215   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_Y_SIZE:         return GET_METRIC_Y (OS2, ySubscriptYSize);
 216   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_X_OFFSET:       return GET_METRIC_X (OS2, ySubscriptXOffset);
 217   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_Y_OFFSET:       return GET_METRIC_Y (OS2, ySubscriptYOffset);
 218   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_X_SIZE:       return GET_METRIC_X (OS2, ySuperscriptXSize);
 219   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_Y_SIZE:       return GET_METRIC_Y (OS2, ySuperscriptYSize);
 220   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_X_OFFSET:     return GET_METRIC_X (OS2, ySuperscriptXOffset);
 221   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_Y_OFFSET:     return GET_METRIC_Y (OS2, ySuperscriptYOffset);
 222   case HB_OT_METRICS_TAG_STRIKEOUT_SIZE:              return GET_METRIC_Y (OS2, yStrikeoutSize);
 223   case HB_OT_METRICS_TAG_STRIKEOUT_OFFSET:            return GET_METRIC_Y (OS2, yStrikeoutPosition);
 224   case HB_OT_METRICS_TAG_UNDERLINE_SIZE:              return GET_METRIC_Y (post->table, underlineThickness);
 225   case HB_OT_METRICS_TAG_UNDERLINE_OFFSET:            return GET_METRIC_Y (post->table, underlinePosition);
 226
 227   /* Private tags */
 228   case _HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER_OS2:    return GET_METRIC_Y (OS2, sTypoAscender);
 229   case _HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER_HHEA:   return GET_METRIC_Y (hhea, ascender);
 230   case _HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER_OS2:   return GET_METRIC_Y (OS2, sTypoDescender);
 231   case _HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER_HHEA:  return GET_METRIC_Y (hhea, descender);
 232   case _HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP_OS2:    return GET_METRIC_Y (OS2, sTypoLineGap);
 233   case _HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP_HHEA:   return GET_METRIC_Y (hhea, lineGap);
 234 #undef GET_METRIC_Y
 235 #undef GET_METRIC_X
 236 #undef GET_VAR
 237   default:                                        return false;
 238   }
 239 }
 240
 241 /**
 242  * hb_ot_metrics_get_position_with_fallback:
 243  * @font: an #hb_font_t object.
 244  * @metrics_tag: tag of metrics value you like to fetch.
 245  * @position: (out) (optional): result of metrics value from the font.
 246  *
 247  * Fetches metrics value corresponding to @metrics_tag from @font,
 248  * and synthesizes a value if it the value is missing in the font.
 249  *
 250  * Since: 4.0.0
 251  **/
 252 void
 253 hb_ot_metrics_get_position_with_fallback (hb_font_t           *font,
 254                                           hb_ot_metrics_tag_t  metrics_tag,
 255                                           hb_position_t       *position     /* OUT */)
 256 {
 257   hb_font_extents_t font_extents;
 258   hb_codepoint_t glyph;
 259   hb_glyph_extents_t extents;
 260
 261   if (hb_ot_metrics_get_position (font, metrics_tag, position))
 262     {
 263       if ((metrics_tag != HB_OT_METRICS_TAG_STRIKEOUT_SIZE &&
 264            metrics_tag != HB_OT_METRICS_TAG_UNDERLINE_SIZE) ||
 265           *position != 0)
 266         return;
 267     }
 268
 269   switch (metrics_tag)
 270   {
 271   case HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER:
 272   case HB_OT_METRICS_TAG_HORIZONTAL_CLIPPING_ASCENT:
 273     hb_font_get_extents_for_direction (font, HB_DIRECTION_LTR, &font_extents);
 274     *position = font_extents.ascender;
 275     break;
 276
 277   case HB_OT_METRICS_TAG_VERTICAL_ASCENDER:
 278     hb_font_get_extents_for_direction (font, HB_DIRECTION_TTB, &font_extents);
 279     *position = font_extents.ascender;
 280     break;
 281
 282   case HB_OT_METRICS_TAG_HORIZONTAL_DESCENDER:
 283   case HB_OT_METRICS_TAG_HORIZONTAL_CLIPPING_DESCENT:
 284     hb_font_get_extents_for_direction (font, HB_DIRECTION_LTR, &font_extents);
 285     *position = font_extents.descender;
 286     break;
 287
 288   case HB_OT_METRICS_TAG_VERTICAL_DESCENDER:
 289     hb_font_get_extents_for_direction (font, HB_DIRECTION_TTB, &font_extents);
 290     *position = font_extents.ascender;
 291     break;
 292
 293   case HB_OT_METRICS_TAG_HORIZONTAL_LINE_GAP:
 294     hb_font_get_extents_for_direction (font, HB_DIRECTION_LTR, &font_extents);
 295     *position = font_extents.line_gap;
 296     break;
 297
 298   case HB_OT_METRICS_TAG_VERTICAL_LINE_GAP:
 299     hb_font_get_extents_for_direction (font, HB_DIRECTION_TTB, &font_extents);
 300     *position = font_extents.line_gap;
 301     break;
 302
 303   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_RISE:
 304   case HB_OT_METRICS_TAG_VERTICAL_CARET_RISE:
 305     *position = 1;
 306     break;
 307
 308   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_RUN:
 309   case HB_OT_METRICS_TAG_VERTICAL_CARET_RUN:
 310     *position = 0;
 311     break;
 312
 313   case HB_OT_METRICS_TAG_HORIZONTAL_CARET_OFFSET:
 314   case HB_OT_METRICS_TAG_VERTICAL_CARET_OFFSET:
 315     *position = 0;
 316     break;
 317
 318   case HB_OT_METRICS_TAG_X_HEIGHT:
 319     if (hb_font_get_nominal_glyph (font, 'x', &glyph) &&
 320         hb_font_get_glyph_extents (font, glyph, &extents))
 321       *position = extents.y_bearing;
 322     else
 323       *position = font->y_scale / 2;
 324     break;
 325
 326   case HB_OT_METRICS_TAG_CAP_HEIGHT:
 327     if (hb_font_get_nominal_glyph (font, 'O', &glyph) &&
 328         hb_font_get_glyph_extents (font, glyph, &extents))
 329       *position = extents.height + 2 * extents.y_bearing;
 330     else
 331       *position = font->y_scale * 2 / 3;
 332     break;
 333
 334   case HB_OT_METRICS_TAG_STRIKEOUT_SIZE:
 335   case HB_OT_METRICS_TAG_UNDERLINE_SIZE:
 336     *position = font->y_scale / 18;
 337     break;
 338
 339   case HB_OT_METRICS_TAG_STRIKEOUT_OFFSET:
 340     {
 341       hb_position_t ascender;
 342       hb_ot_metrics_get_position_with_fallback (font,
 343                                                 HB_OT_METRICS_TAG_HORIZONTAL_ASCENDER,
 344                                                 &ascender);
 345       *position = ascender / 2;
 346     }
 347     break;
 348
 349   case HB_OT_METRICS_TAG_UNDERLINE_OFFSET:
 350     *position = - font->y_scale / 18;
 351     break;
 352
 353   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_X_SIZE:
 354   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_X_SIZE:
 355     *position = font->x_scale * 10 / 12;
 356     break;
 357
 358   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_Y_SIZE:
 359   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_Y_SIZE:
 360     *position = font->y_scale * 10 / 12;
 361     break;
 362
 363   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_X_OFFSET:
 364   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_X_OFFSET:
 365     *position = 0;
 366     break;
 367
 368   case HB_OT_METRICS_TAG_SUBSCRIPT_EM_Y_OFFSET:
 369   case HB_OT_METRICS_TAG_SUPERSCRIPT_EM_Y_OFFSET:
 370     *position = font->y_scale / 5;
 371     break;
 372
 373   case _HB_OT_METRICS_TAG_MAX_VALUE:
 374   default:
 375     *position = 0;
 376     break;
 377   }
 378 }
 379
 380 #ifndef HB_NO_VAR
 381 /**
 382  * hb_ot_metrics_get_variation:
 383  * @font: an #hb_font_t object.
 384  * @metrics_tag: tag of metrics value you like to fetch.
 385  *
 386  * Fetches metrics value corresponding to @metrics_tag from @font with the
 387  * current font variation settings applied.
 388  *
 389  * Returns: The requested metric value.
 390  *
 391  * Since: 2.6.0
 392  **/
 393 float
 394 hb_ot_metrics_get_variation (hb_font_t *font, hb_ot_metrics_tag_t metrics_tag)
 395 {
 396   return font->face->table.MVAR->get_var (metrics_tag, font->coords, font->num_coords);
 397 }
 398
 399 /**
 400  * hb_ot_metrics_get_x_variation:
 401  * @font: an #hb_font_t object.
 402  * @metrics_tag: tag of metrics value you like to fetch.
 403  *
 404  * Fetches horizontal metrics value corresponding to @metrics_tag from @font
 405  * with the current font variation settings applied.
 406  *
 407  * Returns: The requested metric value.
 408  *
 409  * Since: 2.6.0
 410  **/
 411 hb_position_t
 412 hb_ot_metrics_get_x_variation (hb_font_t *font, hb_ot_metrics_tag_t metrics_tag)
 413 {
 414   return font->em_scalef_x (hb_ot_metrics_get_variation (font, metrics_tag));
 415 }
 416
 417 /**
 418  * hb_ot_metrics_get_y_variation:
 419  * @font: an #hb_font_t object.
 420  * @metrics_tag: tag of metrics value you like to fetch.
 421  *
 422  * Fetches vertical metrics value corresponding to @metrics_tag from @font with
 423  * the current font variation settings applied.
 424  *
 425  * Returns: The requested metric value.
 426  *
 427  * Since: 2.6.0
 428  **/
 429 hb_position_t
 430 hb_ot_metrics_get_y_variation (hb_font_t *font, hb_ot_metrics_tag_t metrics_tag)
 431 {
 432   return font->em_scalef_y (hb_ot_metrics_get_variation (font, metrics_tag));
 433 }
 434 #endif
 435
 436 #endif