gfx/harfbuzz/src/hb-style.cc

   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, then tries to get default style values from different
  65  * 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