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Diffstat (limited to 'src/3rdparty/freetype/include/freetype/ftttdrv.h')
| -rw-r--r-- | src/3rdparty/freetype/include/freetype/ftttdrv.h | 310 |
1 files changed, 0 insertions, 310 deletions
diff --git a/src/3rdparty/freetype/include/freetype/ftttdrv.h b/src/3rdparty/freetype/include/freetype/ftttdrv.h deleted file mode 100644 index dc0081a0b9..0000000000 --- a/src/3rdparty/freetype/include/freetype/ftttdrv.h +++ /dev/null @@ -1,310 +0,0 @@ -/***************************************************************************/ -/* */ -/* ftttdrv.h */ -/* */ -/* FreeType API for controlling the TrueType driver */ -/* (specification only). */ -/* */ -/* Copyright 2013-2015 by */ -/* David Turner, Robert Wilhelm, and Werner Lemberg. */ -/* */ -/* This file is part of the FreeType project, and may only be used, */ -/* modified, and distributed under the terms of the FreeType project */ -/* license, LICENSE.TXT. By continuing to use, modify, or distribute */ -/* this file you indicate that you have read the license and */ -/* understand and accept it fully. */ -/* */ -/***************************************************************************/ - - -#ifndef __FTTTDRV_H__ -#define __FTTTDRV_H__ - -#include <ft2build.h> -#include FT_FREETYPE_H - -#ifdef FREETYPE_H -#error "freetype.h of FreeType 1 has been loaded!" -#error "Please fix the directory search order for header files" -#error "so that freetype.h of FreeType 2 is found first." -#endif - - -FT_BEGIN_HEADER - - - /************************************************************************** - * - * @section: - * tt_driver - * - * @title: - * The TrueType driver - * - * @abstract: - * Controlling the TrueType driver module. - * - * @description: - * While FreeType's TrueType driver doesn't expose API functions by - * itself, it is possible to control its behaviour with @FT_Property_Set - * and @FT_Property_Get. The following lists the available properties - * together with the necessary macros and structures. - * - * The TrueType driver's module name is `truetype'. - * - * We start with a list of definitions, kindly provided by Greg - * Hitchcock. - * - * _Bi-Level_ _Rendering_ - * - * Monochromatic rendering, exclusively used in the early days of - * TrueType by both Apple and Microsoft. Microsoft's GDI interface - * supported hinting of the right-side bearing point, such that the - * advance width could be non-linear. Most often this was done to - * achieve some level of glyph symmetry. To enable reasonable - * performance (e.g., not having to run hinting on all glyphs just to - * get the widths) there was a bit in the head table indicating if the - * side bearing was hinted, and additional tables, `hdmx' and `LTSH', to - * cache hinting widths across multiple sizes and device aspect ratios. - * - * _Font_ _Smoothing_ - * - * Microsoft's GDI implementation of anti-aliasing. Not traditional - * anti-aliasing as the outlines were hinted before the sampling. The - * widths matched the bi-level rendering. - * - * _ClearType_ _Rendering_ - * - * Technique that uses physical subpixels to improve rendering on LCD - * (and other) displays. Because of the higher resolution, many methods - * of improving symmetry in glyphs through hinting the right-side - * bearing were no longer necessary. This lead to what GDI calls - * `natural widths' ClearType, see - * http://www.beatstamm.com/typography/RTRCh4.htm#Sec21. Since hinting - * has extra resolution, most non-linearity went away, but it is still - * possible for hints to change the advance widths in this mode. - * - * _ClearType_ _Compatible_ _Widths_ - * - * One of the earliest challenges with ClearType was allowing the - * implementation in GDI to be selected without requiring all UI and - * documents to reflow. To address this, a compatible method of - * rendering ClearType was added where the font hints are executed once - * to determine the width in bi-level rendering, and then re-run in - * ClearType, with the difference in widths being absorbed in the font - * hints for ClearType (mostly in the white space of hints); see - * http://www.beatstamm.com/typography/RTRCh4.htm#Sec20. Somewhat by - * definition, compatible width ClearType allows for non-linear widths, - * but only when the bi-level version has non-linear widths. - * - * _ClearType_ _Subpixel_ _Positioning_ - * - * One of the nice benefits of ClearType is the ability to more crisply - * display fractional widths; unfortunately, the GDI model of integer - * bitmaps did not support this. However, the WPF and Direct Write - * frameworks do support fractional widths. DWrite calls this `natural - * mode', not to be confused with GDI's `natural widths'. Subpixel - * positioning, in the current implementation of Direct Write, - * unfortunately does not support hinted advance widths, see - * http://www.beatstamm.com/typography/RTRCh4.htm#Sec22. Note that the - * TrueType interpreter fully allows the advance width to be adjusted in - * this mode, just the DWrite client will ignore those changes. - * - * _ClearType_ _Backwards_ _Compatibility_ - * - * This is a set of exceptions made in the TrueType interpreter to - * minimize hinting techniques that were problematic with the extra - * resolution of ClearType; see - * http://www.beatstamm.com/typography/RTRCh4.htm#Sec1 and - * http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx. - * This technique is not to be confused with ClearType compatible - * widths. ClearType backwards compatibility has no direct impact on - * changing advance widths, but there might be an indirect impact on - * disabling some deltas. This could be worked around in backwards - * compatibility mode. - * - * _Native_ _ClearType_ _Mode_ - * - * (Not to be confused with `natural widths'.) This mode removes all - * the exceptions in the TrueType interpreter when running with - * ClearType. Any issues on widths would still apply, though. - * - */ - - - /************************************************************************** - * - * @property: - * interpreter-version - * - * @description: - * Currently, two versions are available, representing the bytecode - * interpreter with and without subpixel hinting support, - * respectively. The default is subpixel support if - * TT_CONFIG_OPTION_SUBPIXEL_HINTING is defined, and no subpixel - * support otherwise (since it isn't available then). - * - * If subpixel hinting is on, many TrueType bytecode instructions behave - * differently compared to B/W or grayscale rendering (except if `native - * ClearType' is selected by the font). The main idea is to render at a - * much increased horizontal resolution, then sampling down the created - * output to subpixel precision. However, many older fonts are not - * suited to this and must be specially taken care of by applying - * (hardcoded) font-specific tweaks. - * - * Details on subpixel hinting and some of the necessary tweaks can be - * found in Greg Hitchcock's whitepaper at - * `http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'. - * - * The following example code demonstrates how to activate subpixel - * hinting (omitting the error handling). - * - * { - * FT_Library library; - * FT_Face face; - * FT_UInt interpreter_version = TT_INTERPRETER_VERSION_38; - * - * - * FT_Init_FreeType( &library ); - * - * FT_Property_Set( library, "truetype", - * "interpreter-version", - * &interpreter_version ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - */ - - - /************************************************************************** - * - * @enum: - * TT_INTERPRETER_VERSION_XXX - * - * @description: - * A list of constants used for the @interpreter-version property to - * select the hinting engine for Truetype fonts. - * - * The numeric value in the constant names represents the version - * number as returned by the `GETINFO' bytecode instruction. - * - * @values: - * TT_INTERPRETER_VERSION_35 :: - * Version~35 corresponds to MS rasterizer v.1.7 as used e.g. in - * Windows~98; only grayscale and B/W rasterizing is supported. - * - * TT_INTERPRETER_VERSION_38 :: - * Version~38 corresponds to MS rasterizer v.1.9; it is roughly - * equivalent to the hinting provided by DirectWrite ClearType (as - * can be found, for example, in the Internet Explorer~9 running on - * Windows~7). - * - * @note: - * This property controls the behaviour of the bytecode interpreter - * and thus how outlines get hinted. It does *not* control how glyph - * get rasterized! In particular, it does not control subpixel color - * filtering. - * - * If FreeType has not been compiled with configuration option - * FT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 causes an - * `FT_Err_Unimplemented_Feature' error. - * - * Depending on the graphics framework, Microsoft uses different - * bytecode and rendering engines. As a consequence, the version - * numbers returned by a call to the `GETINFO' bytecode instruction are - * more convoluted than desired. - * - * Here are two tables that try to shed some light on the possible - * values for the MS rasterizer engine, together with the additional - * features introduced by it. - * - * { - * GETINFO framework version feature - * ------------------------------------------------------------------- - * 3 GDI (Win 3.1), v1.0 16-bit, first version - * TrueImage - * 33 GDI (Win NT 3.1), v1.5 32-bit - * HP Laserjet - * 34 GDI (Win 95) v1.6 font smoothing, - * new SCANTYPE opcode - * 35 GDI (Win 98/2000) v1.7 (UN)SCALED_COMPONENT_OFFSET - * bits in composite glyphs - * 36 MGDI (Win CE 2) v1.6+ classic ClearType - * 37 GDI (XP and later), v1.8 ClearType - * GDI+ old (before Vista) - * 38 GDI+ old (Vista, Win 7), v1.9 subpixel ClearType, - * WPF Y-direction ClearType, - * additional error checking - * 39 DWrite (before Win 8) v2.0 subpixel ClearType flags - * in GETINFO opcode, - * bug fixes - * 40 GDI+ (after Win 7), v2.1 Y-direction ClearType flag - * DWrite (Win 8) in GETINFO opcode, - * Gray ClearType - * } - * - * The `version' field gives a rough orientation only, since some - * applications provided certain features much earlier (as an example, - * Microsoft Reader used subpixel and Y-direction ClearType already in - * Windows 2000). Similarly, updates to a given framework might include - * improved hinting support. - * - * { - * version sampling rendering comment - * x y x y - * -------------------------------------------------------------- - * v1.0 normal normal B/W B/W bi-level - * v1.6 high high gray gray grayscale - * v1.8 high normal color-filter B/W (GDI) ClearType - * v1.9 high high color-filter gray Color ClearType - * v2.1 high normal gray B/W Gray ClearType - * v2.1 high high gray gray Gray ClearType - * } - * - * Color and Gray ClearType are the two available variants of - * `Y-direction ClearType', meaning grayscale rasterization along the - * Y-direction; the name used in the TrueType specification for this - * feature is `symmetric smoothing'. `Classic ClearType' is the - * original algorithm used before introducing a modified version in - * Win~XP. Another name for v1.6's grayscale rendering is `font - * smoothing', and `Color ClearType' is sometimes also called `DWrite - * ClearType'. To differentiate between today's Color ClearType and the - * earlier ClearType variant with B/W rendering along the vertical axis, - * the latter is sometimes called `GDI ClearType'. - * - * `Normal' and `high' sampling describe the (virtual) resolution to - * access the rasterized outline after the hinting process. `Normal' - * means 1 sample per grid line (i.e., B/W). In the current Microsoft - * implementation, `high' means an extra virtual resolution of 16x16 (or - * 16x1) grid lines per pixel for bytecode instructions like `MIRP'. - * After hinting, these 16 grid lines are mapped to 6x5 (or 6x1) grid - * lines for color filtering if Color ClearType is activated. - * - * Note that `Gray ClearType' is essentially the same as v1.6's - * grayscale rendering. However, the GETINFO instruction handles it - * differently: v1.6 returns bit~12 (hinting for grayscale), while v2.1 - * returns bits~13 (hinting for ClearType), 18 (symmetrical smoothing), - * and~19 (Gray ClearType). Also, this mode respects bits 2 and~3 for - * the version~1 gasp table exclusively (like Color ClearType), while - * v1.6 only respects the values of version~0 (bits 0 and~1). - * - * FreeType doesn't provide all capabilities of the most recent - * ClearType incarnation, thus we identify our subpixel support as - * version~38. - * - */ -#define TT_INTERPRETER_VERSION_35 35 -#define TT_INTERPRETER_VERSION_38 38 - - /* */ - - -FT_END_HEADER - - -#endif /* __FTTTDRV_H__ */ - - -/* END */ |