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Diffstat (limited to 'src/3rdparty/freetype/include/freetype/ftdriver.h')
| -rw-r--r-- | src/3rdparty/freetype/include/freetype/ftdriver.h | 749 |
1 files changed, 378 insertions, 371 deletions
diff --git a/src/3rdparty/freetype/include/freetype/ftdriver.h b/src/3rdparty/freetype/include/freetype/ftdriver.h index e90475b2af..497bde9f6e 100644 --- a/src/3rdparty/freetype/include/freetype/ftdriver.h +++ b/src/3rdparty/freetype/include/freetype/ftdriver.h @@ -1,19 +1,19 @@ -/***************************************************************************/ -/* */ -/* ftdriver.h */ -/* */ -/* FreeType API for controlling driver modules (specification only). */ -/* */ -/* Copyright 2017-2018 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. */ -/* */ -/***************************************************************************/ +/**************************************************************************** + * + * ftdriver.h + * + * FreeType API for controlling driver modules (specification only). + * + * Copyright (C) 2017-2019 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 FTDRIVER_H_ @@ -50,8 +50,8 @@ FT_BEGIN_HEADER * @FT_Property_Get. The following lists the available properties * together with the necessary macros and structures. * - * Note that the auto-hinter's module name is `autofitter' for - * historical reasons. + * Note that the auto-hinter's module name is 'autofitter' for historical + * reasons. * * Available properties are @increase-x-height, @no-stem-darkening * (experimental), @darkening-parameters (experimental), @warping @@ -74,18 +74,18 @@ FT_BEGIN_HEADER * Controlling the CFF driver module. * * @description: - * While FreeType's CFF driver doesn't expose API functions by itself, - * it is possible to control its behaviour with @FT_Property_Set and + * While FreeType's CFF driver doesn't expose API functions by itself, it + * is possible to control its behaviour with @FT_Property_Set and * @FT_Property_Get. * - * The CFF driver's module name is `cff'. + * The CFF driver's module name is 'cff'. * * Available properties are @hinting-engine, @no-stem-darkening, * @darkening-parameters, and @random-seed, as documented in the * @properties section. * * - * *Hinting* *and* *antialiasing* *principles* *of* *the* *new* *engine* + * **Hinting and antialiasing principles of the new engine** * * The rasterizer is positioning horizontal features (e.g., ascender * height & x-height, or crossbars) on the pixel grid and minimizing the @@ -93,35 +93,34 @@ FT_BEGIN_HEADER * features (vertical stems) on the pixel grid without hinting, thus * representing the stem position and weight accurately. Sometimes the * vertical stems may be only partially black. In this context, - * `antialiasing' means that stems are not positioned exactly on pixel + * 'antialiasing' means that stems are not positioned exactly on pixel * borders, causing a fuzzy appearance. * * There are two principles behind this approach. * - * 1) No hinting in the horizontal direction: Unlike `superhinted' + * 1) No hinting in the horizontal direction: Unlike 'superhinted' * TrueType, which changes glyph widths to accommodate regular - * inter-glyph spacing, Adobe's approach is `faithful to the design' in - * representing both the glyph width and the inter-glyph spacing - * designed for the font. This makes the screen display as close as it - * can be to the result one would get with infinite resolution, while - * preserving what is considered the key characteristics of each glyph. - * Note that the distances between unhinted and grid-fitted positions at - * small sizes are comparable to kerning values and thus would be - * noticeable (and distracting) while reading if hinting were applied. + * inter-glyph spacing, Adobe's approach is 'faithful to the design' in + * representing both the glyph width and the inter-glyph spacing designed + * for the font. This makes the screen display as close as it can be to + * the result one would get with infinite resolution, while preserving + * what is considered the key characteristics of each glyph. Note that + * the distances between unhinted and grid-fitted positions at small + * sizes are comparable to kerning values and thus would be noticeable + * (and distracting) while reading if hinting were applied. * * One of the reasons to not hint horizontally is antialiasing for LCD - * screens: The pixel geometry of modern displays supplies three - * vertical subpixels as the eye moves horizontally across each visible - * pixel. On devices where we can be certain this characteristic is - * present a rasterizer can take advantage of the subpixels to add - * increments of weight. In Western writing systems this turns out to - * be the more critical direction anyway; the weights and spacing of - * vertical stems (see above) are central to Armenian, Cyrillic, Greek, - * and Latin type designs. Even when the rasterizer uses greyscale - * antialiasing instead of color (a necessary compromise when one - * doesn't know the screen characteristics), the unhinted vertical - * features preserve the design's weight and spacing much better than - * aliased type would. + * screens: The pixel geometry of modern displays supplies three vertical + * subpixels as the eye moves horizontally across each visible pixel. On + * devices where we can be certain this characteristic is present a + * rasterizer can take advantage of the subpixels to add increments of + * weight. In Western writing systems this turns out to be the more + * critical direction anyway; the weights and spacing of vertical stems + * (see above) are central to Armenian, Cyrillic, Greek, and Latin type + * designs. Even when the rasterizer uses greyscale antialiasing instead + * of color (a necessary compromise when one doesn't know the screen + * characteristics), the unhinted vertical features preserve the design's + * weight and spacing much better than aliased type would. * * 2) Alignment in the vertical direction: Weights and spacing along the * y~axis are less critical; what is much more important is the visual @@ -132,16 +131,16 @@ FT_BEGIN_HEADER * * On the technical side, horizontal alignment zones for ascender, * x-height, and other important height values (traditionally called - * `blue zones') as defined in the font are positioned independently, - * each being rounded to the nearest pixel edge, taking care of - * overshoot suppression at small sizes, stem darkening, and scaling. + * 'blue zones') as defined in the font are positioned independently, + * each being rounded to the nearest pixel edge, taking care of overshoot + * suppression at small sizes, stem darkening, and scaling. * * Hstems (this is, hint values defined in the font to help align * horizontal features) that fall within a blue zone are said to be - * `captured' and are aligned to that zone. Uncaptured stems are moved + * 'captured' and are aligned to that zone. Uncaptured stems are moved * in one of four ways, top edge up or down, bottom edge up or down. - * Unless there are conflicting hstems, the smallest movement is taken - * to minimize distortion. + * Unless there are conflicting hstems, the smallest movement is taken to + * minimize distortion. * */ @@ -158,13 +157,13 @@ FT_BEGIN_HEADER * Controlling the PCF driver module. * * @description: - * While FreeType's PCF driver doesn't expose API functions by itself, - * it is possible to control its behaviour with @FT_Property_Set and + * While FreeType's PCF driver doesn't expose API functions by itself, it + * is possible to control its behaviour with @FT_Property_Set and * @FT_Property_Get. Right now, there is a single property * @no-long-family-names available if FreeType is compiled with * PCF_CONFIG_OPTION_LONG_FAMILY_NAMES. * - * The PCF driver's module name is `pcf'. + * The PCF driver's module name is 'pcf'. * */ @@ -187,15 +186,15 @@ FT_BEGIN_HEADER * Behind the scenes, both drivers use the Adobe CFF engine for hinting; * however, the used properties must be specified separately. * - * The Type~1 driver's module name is `type1'; the CID driver's module - * name is `t1cid'. + * The Type~1 driver's module name is 'type1'; the CID driver's module + * name is 't1cid'. * * Available properties are @hinting-engine, @no-stem-darkening, * @darkening-parameters, and @random-seed, as documented in the * @properties section. * - * Please see the @cff_driver section for more details on the new - * hinting engine. + * Please see the @cff_driver section for more details on the new hinting + * engine. * */ @@ -217,7 +216,7 @@ FT_BEGIN_HEADER * 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'. + * The TrueType driver's module name is 'truetype'. * * A single property @interpreter-version is available, as documented in * the @properties section. @@ -225,36 +224,36 @@ FT_BEGIN_HEADER * We start with a list of definitions, kindly provided by Greg * Hitchcock. * - * _Bi-Level_ _Rendering_ + * _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. + * 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_ + * _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_ + * _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 + * 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://rastertragedy.com/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_ + * _ClearType Compatible Widths_ * * One of the earliest challenges with ClearType was allowing the * implementation in GDI to be selected without requiring all UI and @@ -263,41 +262,41 @@ FT_BEGIN_HEADER * 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 + * http://rastertragedy.com/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_ + * _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 + * 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 + * http://rastertragedy.com/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_ _Backward_ _Compatibility_ + * _ClearType Backward 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://rastertragedy.com/RTRCh4.htm#Sec1 and * https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx. - * This technique is not to be confused with ClearType compatible - * widths. ClearType backward 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 backward - * compatibility mode. + * This technique is not to be confused with ClearType compatible widths. + * ClearType backward 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 backward compatibility + * mode. * - * _Native_ _ClearType_ _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. + * (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. * */ @@ -328,8 +327,8 @@ FT_BEGIN_HEADER * FT_HINTING_XXX * * @description: - * A list of constants used for the @hinting-engine property to - * select the hinting engine for CFF, Type~1, and CID fonts. + * A list of constants used for the @hinting-engine property to select + * the hinting engine for CFF, Type~1, and CID fonts. * * @values: * FT_HINTING_FREETYPE :: @@ -356,45 +355,46 @@ FT_BEGIN_HEADER * hinting-engine * * @description: - * Thanks to Adobe, which contributed a new hinting (and parsing) - * engine, an application can select between `freetype' and `adobe' if - * compiled with CFF_CONFIG_OPTION_OLD_ENGINE. If this configuration - * macro isn't defined, `hinting-engine' does nothing. + * Thanks to Adobe, which contributed a new hinting (and parsing) engine, + * an application can select between 'freetype' and 'adobe' if compiled + * with `CFF_CONFIG_OPTION_OLD_ENGINE`. If this configuration macro + * isn't defined, 'hinting-engine' does nothing. * * The same holds for the Type~1 and CID modules if compiled with - * T1_CONFIG_OPTION_OLD_ENGINE. + * `T1_CONFIG_OPTION_OLD_ENGINE`. * - * For the `cff' module, the default engine is `freetype' if - * CFF_CONFIG_OPTION_OLD_ENGINE is defined, and `adobe' otherwise. + * For the 'cff' module, the default engine is 'freetype' if + * `CFF_CONFIG_OPTION_OLD_ENGINE` is defined, and 'adobe' otherwise. * - * For both the `type1' and `t1cid' modules, the default engine is - * `freetype' if T1_CONFIG_OPTION_OLD_ENGINE is defined, and `adobe' + * For both the 'type1' and 't1cid' modules, the default engine is + * 'freetype' if `T1_CONFIG_OPTION_OLD_ENGINE` is defined, and 'adobe' * otherwise. * + * @note: + * This property can be used with @FT_Property_Get also. + * + * This property can be set via the `FREETYPE_PROPERTIES` environment + * variable (using values 'adobe' or 'freetype'). + * + * @example: * The following example code demonstrates how to select Adobe's hinting - * engine for the `cff' module (omitting the error handling). + * engine for the 'cff' module (omitting the error handling). * - * { + * ``` * FT_Library library; - * FT_UInt hinting_engine = FT_CFF_HINTING_ADOBE; + * FT_UInt hinting_engine = FT_HINTING_ADOBE; * * * FT_Init_FreeType( &library ); * * FT_Property_Set( library, "cff", * "hinting-engine", &hinting_engine ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - * This property can be set via the `FREETYPE_PROPERTIES' environment - * variable (using values `adobe' or `freetype'). + * ``` * * @since: - * 2.4.12 (for `cff' module) + * 2.4.12 (for 'cff' module) * - * 2.9 (for `type1' and `t1cid' modules) + * 2.9 (for 'type1' and 't1cid' modules) * */ @@ -405,10 +405,10 @@ FT_BEGIN_HEADER * no-stem-darkening * * @description: - * All glyphs that pass through the auto-hinter will be emboldened - * unless this property is set to TRUE. The same is true for the CFF, - * Type~1, and CID font modules if the `Adobe' engine is selected (which - * is the default). + * All glyphs that pass through the auto-hinter will be emboldened unless + * this property is set to TRUE. The same is true for the CFF, Type~1, + * and CID font modules if the 'Adobe' engine is selected (which is the + * default). * * Stem darkening emboldens glyphs at smaller sizes to make them more * readable on common low-DPI screens when using linear alpha blending @@ -419,30 +419,38 @@ FT_BEGIN_HEADER * Gamma correction essentially lightens fonts since shades of grey are * shifted to higher pixel values (=~higher brightness) to match the * original intention to the reality of our screens. The side-effect is - * that glyphs `thin out'. Mac OS~X and Adobe's proprietary font + * that glyphs 'thin out'. Mac OS~X and Adobe's proprietary font * rendering library implement a counter-measure: stem darkening at * smaller sizes where shades of gray dominate. By emboldening a glyph * slightly in relation to its pixel size, individual pixels get higher - * coverage of filled-in outlines and are therefore `blacker'. This - * counteracts the `thinning out' of glyphs, making text remain readable + * coverage of filled-in outlines and are therefore 'blacker'. This + * counteracts the 'thinning out' of glyphs, making text remain readable * at smaller sizes. * * By default, the Adobe engines for CFF, Type~1, and CID fonts darken - * stems at smaller sizes, regardless of hinting, to enhance contrast. + * stems at smaller sizes, regardless of hinting, to enhance contrast. * Setting this property, stem darkening gets switched off. * - * For the auto-hinter, stem-darkening is experimental currently and - * thus switched off by default (this is, `no-stem-darkening' is set to - * TRUE by default). Total consistency with the CFF driver is not - * achieved right now because the emboldening method differs and glyphs - * must be scaled down on the Y-axis to keep outline points inside their + * For the auto-hinter, stem-darkening is experimental currently and thus + * switched off by default (this is, `no-stem-darkening` is set to TRUE + * by default). Total consistency with the CFF driver is not achieved + * right now because the emboldening method differs and glyphs must be + * scaled down on the Y-axis to keep outline points inside their * precomputed blue zones. The smaller the size (especially 9ppem and * down), the higher the loss of emboldening versus the CFF driver. * - * Note that stem darkening is never applied if @FT_LOAD_NO_SCALE is - * set. + * Note that stem darkening is never applied if @FT_LOAD_NO_SCALE is set. + * + * @note: + * This property can be used with @FT_Property_Get also. + * + * This property can be set via the `FREETYPE_PROPERTIES` environment + * variable (using values 1 and 0 for 'on' and 'off', respectively). It + * can also be set per face using @FT_Face_Properties with + * @FT_PARAM_TAG_STEM_DARKENING. * - * { + * @example: + * ``` * FT_Library library; * FT_Bool no_stem_darkening = TRUE; * @@ -451,22 +459,14 @@ FT_BEGIN_HEADER * * FT_Property_Set( library, "cff", * "no-stem-darkening", &no_stem_darkening ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - * This property can be set via the `FREETYPE_PROPERTIES' environment - * variable (using values 1 and 0 for `on' and `off', respectively). - * It can also be set per face using @FT_Face_Properties with - * @FT_PARAM_TAG_STEM_DARKENING. + * ``` * * @since: - * 2.4.12 (for `cff' module) + * 2.4.12 (for 'cff' module) * - * 2.6.2 (for `autofitter' module) + * 2.6.2 (for 'autofitter' module) * - * 2.9 (for `type1' and `t1cid' modules) + * 2.9 (for 'type1' and 't1cid' modules) * */ @@ -478,43 +478,29 @@ FT_BEGIN_HEADER * * @description: * By default, the Adobe hinting engine, as used by the CFF, Type~1, and - * CID font drivers, darkens stems as follows (if the - * `no-stem-darkening' property isn't set): + * CID font drivers, darkens stems as follows (if the `no-stem-darkening` + * property isn't set): * - * { + * ``` * stem width <= 0.5px: darkening amount = 0.4px * stem width = 1px: darkening amount = 0.275px * stem width = 1.667px: darkening amount = 0.275px * stem width >= 2.333px: darkening amount = 0px - * } + * ``` * * and piecewise linear in-between. At configuration time, these four * control points can be set with the macro - * `CFF_CONFIG_OPTION_DARKENING_PARAMETERS'; the CFF, Type~1, and CID + * `CFF_CONFIG_OPTION_DARKENING_PARAMETERS`; the CFF, Type~1, and CID * drivers share these values. At runtime, the control points can be - * changed using the `darkening-parameters' property, as the following - * example demonstrates for the Type~1 driver. - * - * { - * FT_Library library; - * FT_Int darken_params[8] = { 500, 300, // x1, y1 - * 1000, 200, // x2, y2 - * 1500, 100, // x3, y3 - * 2000, 0 }; // x4, y4 - * - * - * FT_Init_FreeType( &library ); - * - * FT_Property_Set( library, "type1", - * "darkening-parameters", darken_params ); - * } + * changed using the `darkening-parameters` property (see the example + * below that demonstrates this for the Type~1 driver). * * The x~values give the stem width, and the y~values the darkening * amount. The unit is 1000th of pixels. All coordinate values must be - * positive; the x~values must be monotonically increasing; the - * y~values must be monotonically decreasing and smaller than or - * equal to 500 (corresponding to half a pixel); the slope of each - * linear piece must be shallower than -1 (e.g., -.4). + * positive; the x~values must be monotonically increasing; the y~values + * must be monotonically decreasing and smaller than or equal to 500 + * (corresponding to half a pixel); the slope of each linear piece must + * be shallower than -1 (e.g., -.4). * * The auto-hinter provides this property, too, as an experimental * feature. See @no-stem-darkening for more. @@ -522,21 +508,36 @@ FT_BEGIN_HEADER * @note: * This property can be used with @FT_Property_Get also. * - * This property can be set via the `FREETYPE_PROPERTIES' environment + * This property can be set via the `FREETYPE_PROPERTIES` environment * variable, using eight comma-separated integers without spaces. Here - * the above example, using `\' to break the line for readability. + * the above example, using `\` to break the line for readability. * - * { + * ``` * FREETYPE_PROPERTIES=\ * type1:darkening-parameters=500,300,1000,200,1500,100,2000,0 - * } + * ``` + * + * @example: + * ``` + * FT_Library library; + * FT_Int darken_params[8] = { 500, 300, // x1, y1 + * 1000, 200, // x2, y2 + * 1500, 100, // x3, y3 + * 2000, 0 }; // x4, y4 + * + * + * FT_Init_FreeType( &library ); + * + * FT_Property_Set( library, "type1", + * "darkening-parameters", darken_params ); + * ``` * * @since: - * 2.5.1 (for `cff' module) + * 2.5.1 (for 'cff' module) * - * 2.6.2 (for `autofitter' module) + * 2.6.2 (for 'autofitter' module) * - * 2.9 (for `type1' and `t1cid' modules) + * 2.9 (for 'type1' and 't1cid' modules) * */ @@ -547,29 +548,29 @@ FT_BEGIN_HEADER * random-seed * * @description: - * By default, the seed value for the CFF `random' operator and the - * similar `0 28 callothersubr pop' command for the Type~1 and CID + * By default, the seed value for the CFF 'random' operator and the + * similar '0 28 callothersubr pop' command for the Type~1 and CID * drivers is set to a random value. However, mainly for debugging - * purposes, it is often necessary to use a known value as a seed so - * that the pseudo-random number sequences generated by `random' are + * purposes, it is often necessary to use a known value as a seed so that + * the pseudo-random number sequences generated by 'random' are * repeatable. * - * The `random-seed' property does that. Its argument is a signed 32bit + * The `random-seed` property does that. Its argument is a signed 32bit * integer; if the value is zero or negative, the seed given by the - * `intitialRandomSeed' private DICT operator in a CFF file gets used - * (or a default value if there is no such operator). If the value is - * positive, use it instead of `initialRandomSeed', which is - * consequently ignored. + * `intitialRandomSeed` private DICT operator in a CFF file gets used (or + * a default value if there is no such operator). If the value is + * positive, use it instead of `initialRandomSeed`, which is consequently + * ignored. * * @note: - * This property can be set via the `FREETYPE_PROPERTIES' environment + * This property can be set via the `FREETYPE_PROPERTIES` environment * variable. It can also be set per face using @FT_Face_Properties with * @FT_PARAM_TAG_RANDOM_SEED. * * @since: - * 2.8 (for `cff' module) + * 2.8 (for 'cff' module) * - * 2.9 (for `type1' and `t1cid' modules) + * 2.9 (for 'type1' and 't1cid' modules) * */ @@ -580,21 +581,28 @@ FT_BEGIN_HEADER * no-long-family-names * * @description: - * If PCF_CONFIG_OPTION_LONG_FAMILY_NAMES is active while compiling + * If `PCF_CONFIG_OPTION_LONG_FAMILY_NAMES` is active while compiling * FreeType, the PCF driver constructs long family names. * - * There are many PCF fonts just called `Fixed' which look completely + * There are many PCF fonts just called 'Fixed' which look completely * different, and which have nothing to do with each other. When - * selecting `Fixed' in KDE or Gnome one gets results that appear rather - * random, the style changes often if one changes the size and one - * cannot select some fonts at all. The improve this situation, the PCF - * module prepends the foundry name (plus a space) to the family name. - * It also checks whether there are `wide' characters; all put together, - * family names like `Sony Fixed' or `Misc Fixed Wide' are constructed. + * selecting 'Fixed' in KDE or Gnome one gets results that appear rather + * random, the style changes often if one changes the size and one cannot + * select some fonts at all. The improve this situation, the PCF module + * prepends the foundry name (plus a space) to the family name. It also + * checks whether there are 'wide' characters; all put together, family + * names like 'Sony Fixed' or 'Misc Fixed Wide' are constructed. + * + * If `no-long-family-names` is set, this feature gets switched off. * - * If `no-long-family-names' is set, this feature gets switched off. + * @note: + * This property can be used with @FT_Property_Get also. * - * { + * This property can be set via the `FREETYPE_PROPERTIES` environment + * variable (using values 1 and 0 for 'on' and 'off', respectively). + * + * @example: + * ``` * FT_Library library; * FT_Bool no_long_family_names = TRUE; * @@ -604,13 +612,7 @@ FT_BEGIN_HEADER * FT_Property_Set( library, "pcf", * "no-long-family-names", * &no_long_family_names ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - * This property can be set via the `FREETYPE_PROPERTIES' environment - * variable (using values 1 and 0 for `on' and `off', respectively). + * ``` * * @since: * 2.8 @@ -626,8 +628,8 @@ FT_BEGIN_HEADER * 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. + * The numeric value in the constant names represents the version number + * as returned by the 'GETINFO' bytecode instruction. * * @values: * TT_INTERPRETER_VERSION_35 :: @@ -638,38 +640,37 @@ FT_BEGIN_HEADER * 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). It is used in FreeType to select the `Infinality' - * subpixel hinting code. The code may be removed in a future - * version. + * Windows~7). It is used in FreeType to select the 'Infinality' + * subpixel hinting code. The code may be removed in a future version. * * TT_INTERPRETER_VERSION_40 :: * Version~40 corresponds to MS rasterizer v.2.1; it is roughly * equivalent to the hinting provided by DirectWrite ClearType (as can * be found, for example, in Microsoft's Edge Browser on Windows~10). - * It is used in FreeType to select the `minimal' subpixel hinting + * It is used in FreeType to select the 'minimal' subpixel hinting * code, a stripped-down and higher performance version of the - * `Infinality' code. + * 'Infinality' code. * * @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 + * 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 the configuration option - * TT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 or~40 causes - * an `FT_Err_Unimplemented_Feature' error. + * `TT_CONFIG_OPTION_SUBPIXEL_HINTING`, selecting version~38 or~40 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. + * 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. + * 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 @@ -692,15 +693,15 @@ FT_BEGIN_HEADER * 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 + * 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 * -------------------------------------------------------------- @@ -710,38 +711,38 @@ FT_BEGIN_HEADER * 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 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' + * 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'. + * 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). + * 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). * - * Keep in mind that the features of the above interpreter versions - * might not map exactly to FreeType features or behavior because it is - * a fundamentally different library with different internals. + * Keep in mind that the features of the above interpreter versions might + * not map exactly to FreeType features or behavior because it is a + * fundamentally different library with different internals. * */ #define TT_INTERPRETER_VERSION_35 35 @@ -755,33 +756,40 @@ FT_BEGIN_HEADER * interpreter-version * * @description: - * Currently, three versions are available, two representing the - * bytecode interpreter with subpixel hinting support (old `Infinality' - * code and new stripped-down and higher performance `minimal' code) and - * one without, 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). + * Currently, three versions are available, two representing the bytecode + * interpreter with subpixel hinting support (old 'Infinality' code and + * new stripped-down and higher performance 'minimal' code) and one + * without, 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 + * differently compared to B/W or grayscale rendering (except if 'native * ClearType' is selected by the font). Microsoft's 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) tweaks in Microsoft's interpreter. + * are not suited to this and must be specially taken care of by applying + * (hardcoded) tweaks in Microsoft's interpreter. * * Details on subpixel hinting and some of the necessary tweaks can be * found in Greg Hitchcock's whitepaper at - * `https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'. - * Note that FreeType currently doesn't really `subpixel hint' (6x1, 6x2, + * 'https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'. + * Note that FreeType currently doesn't really 'subpixel hint' (6x1, 6x2, * or 6x5 supersampling) like discussed in the paper. Depending on the * chosen interpreter, it simply ignores instructions on vertical stems * to arrive at very similar results. * + * @note: + * This property can be used with @FT_Property_Get also. + * + * This property can be set via the `FREETYPE_PROPERTIES` environment + * variable (using values '35', '38', or '40'). + * + * @example: * The following example code demonstrates how to deactivate subpixel * hinting (omitting the error handling). * - * { + * ``` * FT_Library library; * FT_Face face; * FT_UInt interpreter_version = TT_INTERPRETER_VERSION_35; @@ -792,13 +800,7 @@ FT_BEGIN_HEADER * FT_Property_Set( library, "truetype", * "interpreter-version", * &interpreter_version ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - * This property can be set via the `FREETYPE_PROPERTIES' environment - * variable (using values `35', `38', or `40'). + * ``` * * @since: * 2.5 @@ -811,7 +813,7 @@ FT_BEGIN_HEADER * glyph-to-script-map * * @description: - * *Experimental* *only* + * **Experimental only** * * The auto-hinter provides various script modules to hint glyphs. * Examples of supported scripts are Latin or CJK. Before a glyph is @@ -819,25 +821,26 @@ FT_BEGIN_HEADER * the script is then determined based on Unicode character ranges, see * below. * - * OpenType fonts, however, often provide much more glyphs than - * character codes (small caps, superscripts, ligatures, swashes, etc.), - * to be controlled by so-called `features'. Handling OpenType features - * can be quite complicated and thus needs a separate library on top of + * OpenType fonts, however, often provide much more glyphs than character + * codes (small caps, superscripts, ligatures, swashes, etc.), to be + * controlled by so-called 'features'. Handling OpenType features can be + * quite complicated and thus needs a separate library on top of * FreeType. * * The mapping between glyph indices and scripts (in the auto-hinter - * sense, see the @FT_AUTOHINTER_SCRIPT_XXX values) is stored as an - * array with `num_glyphs' elements, as found in the font's @FT_Face - * structure. The `glyph-to-script-map' property returns a pointer to - * this array, which can be modified as needed. Note that the - * modification should happen before the first glyph gets processed by - * the auto-hinter so that the global analysis of the font shapes - * actually uses the modified mapping. - * - * The following example code demonstrates how to access it (omitting - * the error handling). - * - * { + * sense, see the @FT_AUTOHINTER_SCRIPT_XXX values) is stored as an array + * with `num_glyphs` elements, as found in the font's @FT_Face structure. + * The `glyph-to-script-map` property returns a pointer to this array, + * which can be modified as needed. Note that the modification should + * happen before the first glyph gets processed by the auto-hinter so + * that the global analysis of the font shapes actually uses the modified + * mapping. + * + * @example: + * The following example code demonstrates how to access it (omitting the + * error handling). + * + * ``` * FT_Library library; * FT_Face face; * FT_Prop_GlyphToScriptMap prop; @@ -854,7 +857,7 @@ FT_BEGIN_HEADER * // adjust `prop.map' as needed right here * * FT_Load_Glyph( face, ..., FT_LOAD_FORCE_AUTOHINT ); - * } + * ``` * * @since: * 2.4.11 @@ -868,7 +871,7 @@ FT_BEGIN_HEADER * FT_AUTOHINTER_SCRIPT_XXX * * @description: - * *Experimental* *only* + * **Experimental only** * * A list of constants used for the @glyph-to-script-map property to * specify the script submodule the auto-hinter should use for hinting a @@ -879,14 +882,14 @@ FT_BEGIN_HEADER * Don't auto-hint this glyph. * * FT_AUTOHINTER_SCRIPT_LATIN :: - * Apply the latin auto-hinter. For the auto-hinter, `latin' is a - * very broad term, including Cyrillic and Greek also since characters - * from those scripts share the same design constraints. + * Apply the latin auto-hinter. For the auto-hinter, 'latin' is a very + * broad term, including Cyrillic and Greek also since characters from + * those scripts share the same design constraints. * * By default, characters from the following Unicode ranges are * assigned to this submodule. * - * { + * ``` * U+0020 - U+007F // Basic Latin (no control characters) * U+00A0 - U+00FF // Latin-1 Supplement (no control characters) * U+0100 - U+017F // Latin Extended-A @@ -915,7 +918,7 @@ FT_BEGIN_HEADER * U+FB00 - U+FB06 // Alphab. Present. Forms (Latin Ligatures) * U+1D400 - U+1D7FF // Mathematical Alphanumeric Symbols * U+1F100 - U+1F1FF // Enclosed Alphanumeric Supplement - * } + * ``` * * FT_AUTOHINTER_SCRIPT_CJK :: * Apply the CJK auto-hinter, covering Chinese, Japanese, Korean, old @@ -924,7 +927,7 @@ FT_BEGIN_HEADER * By default, characters from the following Unicode ranges are * assigned to this submodule. * - * { + * ``` * U+1100 - U+11FF // Hangul Jamo * U+2E80 - U+2EFF // CJK Radicals Supplement * U+2F00 - U+2FDF // Kangxi Radicals @@ -957,7 +960,7 @@ FT_BEGIN_HEADER * U+2A700 - U+2B73F // CJK Unified Ideographs Extension C * U+2B740 - U+2B81F // CJK Unified Ideographs Extension D * U+2F800 - U+2FA1F // CJK Compatibility Ideographs Supplement - * } + * ``` * * FT_AUTOHINTER_SCRIPT_INDIC :: * Apply the indic auto-hinter, covering all major scripts from the @@ -967,7 +970,7 @@ FT_BEGIN_HEADER * By default, characters from the following Unicode ranges are * assigned to this submodule. * - * { + * ``` * U+0900 - U+0DFF // Indic Range * U+0F00 - U+0FFF // Tibetan * U+1900 - U+194F // Limbu @@ -975,7 +978,7 @@ FT_BEGIN_HEADER * U+A800 - U+A82F // Syloti Nagri * U+ABC0 - U+ABFF // Meetei Mayek * U+11800 - U+118DF // Sharada - * } + * ``` * * Note that currently Indic support is rudimentary only, missing blue * zone support. @@ -996,7 +999,7 @@ FT_BEGIN_HEADER * FT_Prop_GlyphToScriptMap * * @description: - * *Experimental* *only* + * **Experimental only** * * The data exchange structure for the @glyph-to-script-map property. * @@ -1018,36 +1021,36 @@ FT_BEGIN_HEADER * fallback-script * * @description: - * *Experimental* *only* - * - * If no auto-hinter script module can be assigned to a glyph, a - * fallback script gets assigned to it (see also the - * @glyph-to-script-map property). By default, this is - * @FT_AUTOHINTER_SCRIPT_CJK. Using the `fallback-script' property, - * this fallback value can be changed. - * - * { - * FT_Library library; - * FT_UInt fallback_script = FT_AUTOHINTER_SCRIPT_NONE; - * - * - * FT_Init_FreeType( &library ); + * **Experimental only** * - * FT_Property_Set( library, "autofitter", - * "fallback-script", &fallback_script ); - * } + * If no auto-hinter script module can be assigned to a glyph, a fallback + * script gets assigned to it (see also the @glyph-to-script-map + * property). By default, this is @FT_AUTOHINTER_SCRIPT_CJK. Using the + * `fallback-script` property, this fallback value can be changed. * * @note: * This property can be used with @FT_Property_Get also. * * It's important to use the right timing for changing this value: The - * creation of the glyph-to-script map that eventually uses the - * fallback script value gets triggered either by setting or reading a + * creation of the glyph-to-script map that eventually uses the fallback + * script value gets triggered either by setting or reading a * face-specific property like @glyph-to-script-map, or by auto-hinting * any glyph from that face. In particular, if you have already created * an @FT_Face structure but not loaded any glyph (using the * auto-hinter), a change of the fallback script will affect this face. * + * @example: + * ``` + * FT_Library library; + * FT_UInt fallback_script = FT_AUTOHINTER_SCRIPT_NONE; + * + * + * FT_Init_FreeType( &library ); + * + * FT_Property_Set( library, "autofitter", + * "fallback-script", &fallback_script ); + * ``` + * * @since: * 2.4.11 * @@ -1060,42 +1063,43 @@ FT_BEGIN_HEADER * default-script * * @description: - * *Experimental* *only* + * **Experimental only** * - * If FreeType gets compiled with FT_CONFIG_OPTION_USE_HARFBUZZ to make - * the HarfBuzz library access OpenType features for getting better - * glyph coverages, this property sets the (auto-fitter) script to be - * used for the default (OpenType) script data of a font's GSUB table. - * Features for the default script are intended for all scripts not - * explicitly handled in GSUB; an example is a `dlig' feature, - * containing the combination of the characters `T', `E', and `L' to - * form a `TEL' ligature. + * If FreeType gets compiled with `FT_CONFIG_OPTION_USE_HARFBUZZ` to make + * the HarfBuzz library access OpenType features for getting better glyph + * coverages, this property sets the (auto-fitter) script to be used for + * the default (OpenType) script data of a font's GSUB table. Features + * for the default script are intended for all scripts not explicitly + * handled in GSUB; an example is a 'dlig' feature, containing the + * combination of the characters 'T', 'E', and 'L' to form a 'TEL' + * ligature. * * By default, this is @FT_AUTOHINTER_SCRIPT_LATIN. Using the - * `default-script' property, this default value can be changed. - * - * { - * FT_Library library; - * FT_UInt default_script = FT_AUTOHINTER_SCRIPT_NONE; - * - * - * FT_Init_FreeType( &library ); - * - * FT_Property_Set( library, "autofitter", - * "default-script", &default_script ); - * } + * `default-script` property, this default value can be changed. * * @note: * This property can be used with @FT_Property_Get also. * * It's important to use the right timing for changing this value: The - * creation of the glyph-to-script map that eventually uses the - * default script value gets triggered either by setting or reading a + * creation of the glyph-to-script map that eventually uses the default + * script value gets triggered either by setting or reading a * face-specific property like @glyph-to-script-map, or by auto-hinting * any glyph from that face. In particular, if you have already created * an @FT_Face structure but not loaded any glyph (using the * auto-hinter), a change of the default script will affect this face. * + * @example: + * ``` + * FT_Library library; + * FT_UInt default_script = FT_AUTOHINTER_SCRIPT_NONE; + * + * + * FT_Init_FreeType( &library ); + * + * FT_Property_Set( library, "autofitter", + * "default-script", &default_script ); + * ``` + * * @since: * 2.5.3 * @@ -1108,13 +1112,20 @@ FT_BEGIN_HEADER * increase-x-height * * @description: - * For ppem values in the range 6~<= ppem <= `increase-x-height', round - * up the font's x~height much more often than normally. If the value - * is set to~0, which is the default, this feature is switched off. Use + * For ppem values in the range 6~<= ppem <= `increase-x-height`, round + * up the font's x~height much more often than normally. If the value is + * set to~0, which is the default, this feature is switched off. Use * this property to improve the legibility of small font sizes if * necessary. * - * { + * @note: + * This property can be used with @FT_Property_Get also. + * + * Set this value right after calling @FT_Set_Char_Size, but before + * loading any glyph (using the auto-hinter). + * + * @example: + * ``` * FT_Library library; * FT_Face face; * FT_Prop_IncreaseXHeight prop; @@ -1129,13 +1140,7 @@ FT_BEGIN_HEADER * * FT_Property_Set( library, "autofitter", * "increase-x-height", &prop ); - * } - * - * @note: - * This property can be used with @FT_Property_Get also. - * - * Set this value right after calling @FT_Set_Char_Size, but before - * loading any glyph (using the auto-hinter). + * ``` * * @since: * 2.4.11 @@ -1166,46 +1171,48 @@ FT_BEGIN_HEADER * warping * * @description: - * *Experimental* *only* + * **Experimental only** * - * If FreeType gets compiled with option AF_CONFIG_OPTION_USE_WARPER to + * If FreeType gets compiled with option `AF_CONFIG_OPTION_USE_WARPER` to * activate the warp hinting code in the auto-hinter, this property * switches warping on and off. * - * Warping only works in `normal' auto-hinting mode replacing it. - * The idea of the code is to slightly scale and shift a glyph along - * the non-hinted dimension (which is usually the horizontal axis) so - * that as much of its segments are aligned (more or less) to the grid. - * To find out a glyph's optimal scaling and shifting value, various - * parameter combinations are tried and scored. + * Warping only works in 'normal' auto-hinting mode replacing it. The + * idea of the code is to slightly scale and shift a glyph along the + * non-hinted dimension (which is usually the horizontal axis) so that as + * much of its segments are aligned (more or less) to the grid. To find + * out a glyph's optimal scaling and shifting value, various parameter + * combinations are tried and scored. * - * By default, warping is off. The example below shows how to switch on - * warping (omitting the error handling). - * - * { - * FT_Library library; - * FT_Bool warping = 1; - * - * - * FT_Init_FreeType( &library ); - * - * FT_Property_Set( library, "autofitter", - * "warping", &warping ); - * } + * By default, warping is off. * * @note: * This property can be used with @FT_Property_Get also. * - * This property can be set via the `FREETYPE_PROPERTIES' environment - * variable (using values 1 and 0 for `on' and `off', respectively). + * This property can be set via the `FREETYPE_PROPERTIES` environment + * variable (using values 1 and 0 for 'on' and 'off', respectively). * * The warping code can also change advance widths. Have a look at the - * `lsb_delta' and `rsb_delta' fields in the @FT_GlyphSlotRec structure + * `lsb_delta` and `rsb_delta` fields in the @FT_GlyphSlotRec structure * for details on improving inter-glyph distances while rendering. * * Since warping is a global property of the auto-hinter it is best to * change its value before rendering any face. Otherwise, you should - * reload all faces that get auto-hinted in `normal' hinting mode. + * reload all faces that get auto-hinted in 'normal' hinting mode. + * + * @example: + * This example shows how to switch on warping (omitting the error + * handling). + * + * ``` + * FT_Library library; + * FT_Bool warping = 1; + * + * + * FT_Init_FreeType( &library ); + * + * FT_Property_Set( library, "autofitter", "warping", &warping ); + * ``` * * @since: * 2.6 |