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  #if !defined(HB_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
      26  #error "Include <hb.h> instead."
      27  #endif
      28  
      29  #ifndef HB_STYLE_H
      30  #define HB_STYLE_H
      31  
      32  #include "hb.h"
      33  
      34  HB_BEGIN_DECLS
      35  
      36  /**
      37   * hb_style_tag_t:
      38   * @HB_STYLE_TAG_ITALIC: Used to vary between non-italic and italic.
      39   * A value of 0 can be interpreted as "Roman" (non-italic); a value of 1 can
      40   * be interpreted as (fully) italic.
      41   * @HB_STYLE_TAG_OPTICAL_SIZE: Used to vary design to suit different text sizes.
      42   * Non-zero. Values can be interpreted as text size, in points.
      43   * @HB_STYLE_TAG_SLANT_ANGLE: Used to vary between upright and slanted text. Values
      44   * must be greater than -90 and less than +90. Values can be interpreted as
      45   * the angle, in counter-clockwise degrees, of oblique slant from whatever the
      46   * designer considers to be upright for that font design. Typical right-leaning
      47   * Italic fonts have a negative slant angle (typically around -12)
      48   * @HB_STYLE_TAG_SLANT_RATIO: same as @HB_STYLE_TAG_SLANT_ANGLE expression as ratio.
      49   * Typical right-leaning Italic fonts have a positive slant ratio (typically around 0.2)
      50   * @HB_STYLE_TAG_WIDTH: Used to vary width of text from narrower to wider.
      51   * Non-zero. Values can be interpreted as a percentage of whatever the font
      52   * designer considers “normal width” for that font design.
      53   * @HB_STYLE_TAG_WEIGHT: Used to vary stroke thicknesses or other design details
      54   * to give variation from lighter to blacker. Values can be interpreted in direct
      55   * comparison to values for usWeightClass in the OS/2 table,
      56   * or the CSS font-weight property.
      57   *
      58   * Defined by [OpenType Design-Variation Axis Tag Registry](https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxisreg).
      59   *
      60   * Since: 3.0.0
      61   **/
      62  typedef enum
      63  {
      64    HB_STYLE_TAG_ITALIC		= HB_TAG ('i','t','a','l'),
      65    HB_STYLE_TAG_OPTICAL_SIZE	= HB_TAG ('o','p','s','z'),
      66    HB_STYLE_TAG_SLANT_ANGLE	= HB_TAG ('s','l','n','t'),
      67    HB_STYLE_TAG_SLANT_RATIO	= HB_TAG ('S','l','n','t'),
      68    HB_STYLE_TAG_WIDTH		= HB_TAG ('w','d','t','h'),
      69    HB_STYLE_TAG_WEIGHT		= HB_TAG ('w','g','h','t'),
      70  
      71    /*< private >*/
      72    _HB_STYLE_TAG_MAX_VALUE	= HB_TAG_MAX_SIGNED /*< skip >*/
      73  } hb_style_tag_t;
      74  
      75  
      76  HB_EXTERN float
      77  hb_style_get_value (hb_font_t *font, hb_style_tag_t style_tag);
      78  
      79  HB_END_DECLS
      80  
      81  #endif /* HB_STYLE_H */