include/harfbuzz/hb-style.h

0001 /*
0002  * Copyright © 2019  Ebrahim Byagowi
0003  *
0004  *  This is part of HarfBuzz, a text shaping library.
0005  *
0006  * Permission is hereby granted, without written agreement and without
0007  * license or royalty fees, to use, copy, modify, and distribute this
0008  * software and its documentation for any purpose, provided that the
0009  * above copyright notice and the following two paragraphs appear in
0010  * all copies of this software.
0011  *
0012  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
0013  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
0014  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
0015  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
0016  * DAMAGE.
0017  *
0018  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
0019  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
0020  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
0021  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
0022  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
0023  */
0024
0025 #if !defined(HB_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
0026 #error "Include <hb.h> instead."
0027 #endif
0028
0029 #ifndef HB_STYLE_H
0030 #define HB_STYLE_H
0031
0032 #include "hb.h"
0033
0034 HB_BEGIN_DECLS
0035
0036 /**
0037  * hb_style_tag_t:
0038  * @HB_STYLE_TAG_ITALIC: Used to vary between non-italic and italic.
0039  * A value of 0 can be interpreted as "Roman" (non-italic); a value of 1 can
0040  * be interpreted as (fully) italic.
0041  * @HB_STYLE_TAG_OPTICAL_SIZE: Used to vary design to suit different text sizes.
0042  * Non-zero. Values can be interpreted as text size, in points.
0043  * @HB_STYLE_TAG_SLANT_ANGLE: Used to vary between upright and slanted text. Values
0044  * must be greater than -90 and less than +90. Values can be interpreted as
0045  * the angle, in counter-clockwise degrees, of oblique slant from whatever the
0046  * designer considers to be upright for that font design. Typical right-leaning
0047  * Italic fonts have a negative slant angle (typically around -12)
0048  * @HB_STYLE_TAG_SLANT_RATIO: same as @HB_STYLE_TAG_SLANT_ANGLE expression as ratio.
0049  * Typical right-leaning Italic fonts have a positive slant ratio (typically around 0.2)
0050  * @HB_STYLE_TAG_WIDTH: Used to vary width of text from narrower to wider.
0051  * Non-zero. Values can be interpreted as a percentage of whatever the font
0052  * designer considers “normal width” for that font design.
0053  * @HB_STYLE_TAG_WEIGHT: Used to vary stroke thicknesses or other design details
0054  * to give variation from lighter to blacker. Values can be interpreted in direct
0055  * comparison to values for usWeightClass in the OS/2 table,
0056  * or the CSS font-weight property.
0057  *
0058  * Defined by [OpenType Design-Variation Axis Tag Registry](https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxisreg).
0059  *
0060  * Since: 3.0.0
0061  **/
0062 typedef enum
0063 {
0064   HB_STYLE_TAG_ITALIC       = HB_TAG ('i','t','a','l'),
0065   HB_STYLE_TAG_OPTICAL_SIZE = HB_TAG ('o','p','s','z'),
0066   HB_STYLE_TAG_SLANT_ANGLE  = HB_TAG ('s','l','n','t'),
0067   HB_STYLE_TAG_SLANT_RATIO  = HB_TAG ('S','l','n','t'),
0068   HB_STYLE_TAG_WIDTH        = HB_TAG ('w','d','t','h'),
0069   HB_STYLE_TAG_WEIGHT       = HB_TAG ('w','g','h','t'),
0070
0071   /*< private >*/
0072   _HB_STYLE_TAG_MAX_VALUE   = HB_TAG_MAX_SIGNED /*< skip >*/
0073 } hb_style_tag_t;
0074
0075
0076 HB_EXTERN float
0077 hb_style_get_value (hb_font_t *font, hb_style_tag_t style_tag);
0078
0079 HB_END_DECLS
0080
0081 #endif /* HB_STYLE_H */