1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/modules/freetype2/include/ftttdrv.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,170 @@
1.4 +/***************************************************************************/
1.5 +/* */
1.6 +/* ftttdrv.h */
1.7 +/* */
1.8 +/* FreeType API for controlling the TrueType driver */
1.9 +/* (specification only). */
1.10 +/* */
1.11 +/* Copyright 2013 by */
1.12 +/* David Turner, Robert Wilhelm, and Werner Lemberg. */
1.13 +/* */
1.14 +/* This file is part of the FreeType project, and may only be used, */
1.15 +/* modified, and distributed under the terms of the FreeType project */
1.16 +/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
1.17 +/* this file you indicate that you have read the license and */
1.18 +/* understand and accept it fully. */
1.19 +/* */
1.20 +/***************************************************************************/
1.21 +
1.22 +
1.23 +#ifndef __FTTTDRV_H__
1.24 +#define __FTTTDRV_H__
1.25 +
1.26 +#include <ft2build.h>
1.27 +#include FT_FREETYPE_H
1.28 +
1.29 +#ifdef FREETYPE_H
1.30 +#error "freetype.h of FreeType 1 has been loaded!"
1.31 +#error "Please fix the directory search order for header files"
1.32 +#error "so that freetype.h of FreeType 2 is found first."
1.33 +#endif
1.34 +
1.35 +
1.36 +FT_BEGIN_HEADER
1.37 +
1.38 +
1.39 + /**************************************************************************
1.40 + *
1.41 + * @section:
1.42 + * tt_driver
1.43 + *
1.44 + * @title:
1.45 + * The TrueType driver
1.46 + *
1.47 + * @abstract:
1.48 + * Controlling the TrueType driver module.
1.49 + *
1.50 + * @description:
1.51 + * While FreeType's TrueType driver doesn't expose API functions by
1.52 + * itself, it is possible to control its behaviour with @FT_Property_Set
1.53 + * and @FT_Property_Get. The following lists the available properties
1.54 + * together with the necessary macros and structures.
1.55 + *
1.56 + * The TrueType driver's module name is `truetype'.
1.57 + *
1.58 + */
1.59 +
1.60 +
1.61 + /**************************************************************************
1.62 + *
1.63 + * @property:
1.64 + * interpreter-version
1.65 + *
1.66 + * @description:
1.67 + * Currently, two versions are available, representing the bytecode
1.68 + * interpreter with and without subpixel hinting support,
1.69 + * respectively. The default is subpixel support if
1.70 + * TT_CONFIG_OPTION_SUBPIXEL_HINTING is defined, and no subpixel
1.71 + * support otherwise (since it isn't available then).
1.72 + *
1.73 + * If subpixel hinting is on, many TrueType bytecode instructions
1.74 + * behave differently compared to B/W or grayscale rendering. The
1.75 + * main idea is to render at a much increased horizontal resolution,
1.76 + * then sampling down the created output to subpixel precision.
1.77 + * However, many older fonts are not suited to this and must be
1.78 + * specially taken care of by applying (hardcoded) font-specific
1.79 + * tweaks.
1.80 + *
1.81 + * Details on subpixel hinting and some of the necessary tweaks can be
1.82 + * found in Greg Hitchcock's whitepaper at
1.83 + * `http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'.
1.84 + *
1.85 + * The following example code demonstrates how to activate subpixel
1.86 + * hinting (omitting the error handling).
1.87 + *
1.88 + * {
1.89 + * FT_Library library;
1.90 + * FT_Face face;
1.91 + * FT_UInt interpreter_version = TT_INTERPRETER_VERSION_38;
1.92 + *
1.93 + *
1.94 + * FT_Init_FreeType( &library );
1.95 + *
1.96 + * FT_Property_Set( library, "truetype",
1.97 + * "interpreter-version",
1.98 + * &interpreter_version );
1.99 + * }
1.100 + *
1.101 + * @note:
1.102 + * This property can be used with @FT_Property_Get also.
1.103 + *
1.104 + */
1.105 +
1.106 +
1.107 + /**************************************************************************
1.108 + *
1.109 + * @enum:
1.110 + * TT_INTERPRETER_VERSION_XXX
1.111 + *
1.112 + * @description:
1.113 + * A list of constants used for the @interpreter-version property to
1.114 + * select the hinting engine for Truetype fonts.
1.115 + *
1.116 + * The numeric value in the constant names represents the version
1.117 + * number as returned by the `GETINFO' bytecode instruction.
1.118 + *
1.119 + * @values:
1.120 + * TT_INTERPRETER_VERSION_35 ::
1.121 + * Version~35 corresponds to MS rasterizer v.1.7 as used e.g. in
1.122 + * Windows~98; only grayscale and B/W rasterizing is supported.
1.123 + *
1.124 + * TT_INTERPRETER_VERSION_38 ::
1.125 + * Version~38 corresponds to MS rasterizer v.1.9; it is roughly
1.126 + * equivalent to the hinting provided by DirectWrite ClearType (as
1.127 + * can be found, for example, in the Internet Explorer~9 running on
1.128 + * Windows~7).
1.129 + *
1.130 + * @note:
1.131 + * This property controls the behaviour of the bytecode interpreter
1.132 + * and thus how outlines get hinted. It does *not* control how glyph
1.133 + * get rasterized! In particular, it does not control subpixel color
1.134 + * filtering.
1.135 + *
1.136 + * If FreeType has not been compiled with configuration option
1.137 + * FT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 causes an
1.138 + * `FT_Err_Unimplemented_Feature' error.
1.139 + *
1.140 + * Depending on the graphics framework, Microsoft uses different
1.141 + * bytecode engines. As a consequence, the version numbers returned by
1.142 + * a call to the `GETINFO[1]' bytecode instruction are more convoluted
1.143 + * than desired.
1.144 + *
1.145 + * {
1.146 + * framework Windows version result of GETINFO[1]
1.147 + * ----------------------------------------------------
1.148 + * GDI before XP 35
1.149 + * GDI XP and later 37
1.150 + * GDI+ old before Vista 37
1.151 + * GDI+ old Vista, 7 38
1.152 + * GDI+ after 7 40
1.153 + * DWrite before 8 39
1.154 + * DWrite 8 and later 40
1.155 + * }
1.156 + *
1.157 + * Since FreeType doesn't provide all capabilities of DWrite ClearType,
1.158 + * using version~38 seems justified.
1.159 + *
1.160 + */
1.161 +#define TT_INTERPRETER_VERSION_35 35
1.162 +#define TT_INTERPRETER_VERSION_38 38
1.163 +
1.164 +
1.165 + /* */
1.166 +
1.167 +FT_END_HEADER
1.168 +
1.169 +
1.170 +#endif /* __FTTTDRV_H__ */
1.171 +
1.172 +
1.173 +/* END */
