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hb-style.cc (3902B)

      1 /*
      2 * Copyright © 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 #ifndef HB_NO_STYLE
     28 
     29 #include "hb-ot-var-avar-table.hh"
     30 #include "hb-ot-var-fvar-table.hh"
     31 #include "hb-ot-stat-table.hh"
     32 #include "hb-ot-os2-table.hh"
     33 #include "hb-ot-head-table.hh"
     34 #include "hb-ot-post-table.hh"
     35 #include "hb-ot-face.hh"
     36 
     37 /**
     38 * SECTION:hb-style
     39 * @title: hb-style
     40 * @short_description: Font Styles
     41 * @include: hb.h
     42 *
     43 * Functions for fetching style information from fonts.
     44 **/
     45 
     46 static inline float
     47 _hb_angle_to_ratio (float a)
     48 {
     49  return tanf (a * -HB_PI / 180.f);
     50 }
     51 
     52 static inline float
     53 _hb_ratio_to_angle (float r)
     54 {
     55  return atanf (r) * -180.f / HB_PI;
     56 }
     57 
     58 /**
     59 * hb_style_get_value:
     60 * @font: a #hb_font_t object.
     61 * @style_tag: a style tag.
     62 *
     63 * Searches variation axes of a #hb_font_t object for a specific axis first,
     64 * if not set, first tries to get default style values in `STAT` table
     65 * then tries to polyfill from different tables of the font.
     66 *
     67 * Returns: Corresponding axis or default value to a style tag.
     68 *
     69 * Since: 3.0.0
     70 **/
     71 float
     72 hb_style_get_value (hb_font_t *font, hb_style_tag_t style_tag)
     73 {
     74  if (unlikely (style_tag == HB_STYLE_TAG_SLANT_RATIO))
     75    return _hb_angle_to_ratio (hb_style_get_value (font, HB_STYLE_TAG_SLANT_ANGLE));
     76 
     77  hb_face_t *face = font->face;
     78 
     79 #ifndef HB_NO_VAR
     80  hb_ot_var_axis_info_t axis;
     81  if (hb_ot_var_find_axis_info (face, style_tag, &axis))
     82  {
     83    if (axis.axis_index < font->num_coords) return font->design_coords[axis.axis_index];
     84    /* If a face is variable, fvar's default_value is better than STAT records */
     85    return axis.default_value;
     86  }
     87 #endif
     88 
     89  if (style_tag == HB_STYLE_TAG_OPTICAL_SIZE && font->ptem)
     90    return font->ptem;
     91 
     92  /* STAT */
     93  float value;
     94  if (face->table.STAT->get_value (style_tag, &value))
     95    return value;
     96 
     97  switch ((unsigned) style_tag)
     98  {
     99  case HB_STYLE_TAG_ITALIC:
    100    return face->table.OS2->is_italic () || face->table.head->is_italic () ? 1 : 0;
    101  case HB_STYLE_TAG_OPTICAL_SIZE:
    102  {
    103    unsigned int lower, design, upper;
    104    return face->table.OS2->v5 ().get_optical_size (&lower, &upper)
    105    ? (float) (lower + upper) / 2.f
    106    : hb_ot_layout_get_size_params (face, &design, nullptr, nullptr, nullptr, nullptr)
    107    ? design / 10.f
    108    : 12.f;
    109  }
    110  case HB_STYLE_TAG_SLANT_ANGLE:
    111  {
    112    float angle = face->table.post->table->italicAngle.to_float ();
    113 
    114    if (font->slant)
    115      angle = _hb_ratio_to_angle (font->slant + _hb_angle_to_ratio (angle));
    116 
    117    return angle;
    118  }
    119  case HB_STYLE_TAG_WIDTH:
    120    return face->table.OS2->has_data ()
    121    ? face->table.OS2->get_width ()
    122    : (face->table.head->is_condensed () ? 75 :
    123       face->table.head->is_expanded () ? 125 :
    124       100);
    125  case HB_STYLE_TAG_WEIGHT:
    126    return face->table.OS2->has_data ()
    127    ? face->table.OS2->usWeightClass
    128    : (face->table.head->is_bold () ? 700 : 400);
    129  default:
    130    return 0;
    131  }
    132 }
    133 
    134 #endif