diff options
Diffstat (limited to 'src/3rdparty/freetype/include/freetype/ftdriver.h')
| -rw-r--r-- | src/3rdparty/freetype/include/freetype/ftdriver.h | 157 |
1 files changed, 88 insertions, 69 deletions
diff --git a/src/3rdparty/freetype/include/freetype/ftdriver.h b/src/3rdparty/freetype/include/freetype/ftdriver.h index 804ec34a39..7af7465bc7 100644 --- a/src/3rdparty/freetype/include/freetype/ftdriver.h +++ b/src/3rdparty/freetype/include/freetype/ftdriver.h @@ -4,7 +4,7 @@ * * FreeType API for controlling driver modules (specification only). * - * Copyright (C) 2017-2020 by + * Copyright (C) 2017-2023 by * David Turner, Robert Wilhelm, and Werner Lemberg. * * This file is part of the FreeType project, and may only be used, @@ -53,10 +53,10 @@ FT_BEGIN_HEADER * reasons. * * Available properties are @increase-x-height, @no-stem-darkening - * (experimental), @darkening-parameters (experimental), @warping - * (experimental), @glyph-to-script-map (experimental), @fallback-script - * (experimental), and @default-script (experimental), as documented in - * the @properties section. + * (experimental), @darkening-parameters (experimental), + * @glyph-to-script-map (experimental), @fallback-script (experimental), + * and @default-script (experimental), as documented in the @properties + * section. * */ @@ -84,15 +84,15 @@ FT_BEGIN_HEADER * @properties section. * * - * **Hinting and antialiasing principles of the new engine** + * **Hinting and anti-aliasing 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 - * amount of antialiasing applied to them, while placing vertical + * amount of anti-aliasing applied to them, while placing vertical * 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 + * 'anti-aliasing' means that stems are not positioned exactly on pixel * borders, causing a fuzzy appearance. * * There are two principles behind this approach. @@ -108,7 +108,7 @@ FT_BEGIN_HEADER * 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 + * One of the reasons to not hint horizontally is anti-aliasing 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 @@ -116,7 +116,7 @@ FT_BEGIN_HEADER * 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 + * designs. Even when the rasterizer uses greyscale anti-aliasing 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. @@ -134,7 +134,7 @@ FT_BEGIN_HEADER * 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 + * Hstems (that 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 * in one of four ways, top edge up or down, bottom edge up or down. @@ -212,16 +212,14 @@ FT_BEGIN_HEADER * @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'. + * and @FT_Property_Get. * - * A single property @interpreter-version is available, as documented in - * the @properties section. + * The TrueType driver's module name is 'truetype'; a single property + * @interpreter-version is available, as documented in the @properties + * section. * - * We start with a list of definitions, kindly provided by Greg - * Hitchcock. + * To help understand the differences between interpreter versions, we + * introduce a list of definitions, kindly provided by Greg Hitchcock. * * _Bi-Level Rendering_ * @@ -303,6 +301,31 @@ FT_BEGIN_HEADER /************************************************************************** * * @section: + * ot_svg_driver + * + * @title: + * The SVG driver + * + * @abstract: + * Controlling the external rendering of OT-SVG glyphs. + * + * @description: + * By default, FreeType can only load the 'SVG~' table of OpenType fonts + * if configuration macro `FT_CONFIG_OPTION_SVG` is defined. To make it + * render SVG glyphs, an external SVG rendering library is needed. All + * details on the interface between FreeType and the external library + * via function hooks can be found in section @svg_fonts. + * + * The OT-SVG driver's module name is 'ot-svg'; it supports a single + * property called @svg-hooks, documented below in the @properties + * section. + * + */ + + + /************************************************************************** + * + * @section: * properties * * @title: @@ -362,12 +385,8 @@ FT_BEGIN_HEADER * The same holds for the Type~1 and CID modules if compiled with * `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 both the 'type1' and 't1cid' modules, the default engine is - * 'freetype' if `T1_CONFIG_OPTION_OLD_ENGINE` is defined, and 'adobe' - * otherwise. + * For the 'cff' module, the default engine is 'adobe'. For both the + * 'type1' and 't1cid' modules, the default engine is 'adobe', too. * * @note: * This property can be used with @FT_Property_Get also. @@ -427,7 +446,7 @@ FT_BEGIN_HEADER * at smaller sizes. * * For the auto-hinter, stem-darkening is experimental currently and thus - * switched off by default (this is, `no-stem-darkening` is set to TRUE + * switched off by default (that 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 @@ -632,11 +651,8 @@ FT_BEGIN_HEADER * 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). It is used in FreeType to select the 'Infinality' - * subpixel hinting code. The code may be removed in a future version. + * Version~38 is the same Version~40. The original 'Infinality' code is + * no longer available. * * TT_INTERPRETER_VERSION_40 :: * Version~40 corresponds to MS rasterizer v.2.1; it is roughly @@ -801,6 +817,39 @@ FT_BEGIN_HEADER * 2.5 */ + /************************************************************************** + * + * @property: + * svg-hooks + * + * @description: + * Set up the interface between FreeType and an extern SVG rendering + * library like 'librsvg'. All details on the function hooks can be + * found in section @svg_fonts. + * + * @example: + * The following example code expects that the four hook functions + * `svg_*` are defined elsewhere. Error handling is omitted, too. + * + * ``` + * FT_Library library; + * SVG_RendererHooks hooks = { + * (SVG_Lib_Init_Func)svg_init, + * (SVG_Lib_Free_Func)svg_free, + * (SVG_Lib_Render_Func)svg_render, + * (SVG_Lib_Preset_Slot_Func)svg_preset_slot }; + * + * + * FT_Init_FreeType( &library ); + * + * FT_Property_Set( library, "ot-svg", + * "svg-hooks", &hooks ); + * ``` + * + * @since: + * 2.12 + */ + /************************************************************************** * @@ -1166,48 +1215,18 @@ FT_BEGIN_HEADER * warping * * @description: - * **Experimental only** + * **Obsolete** * - * 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. + * This property was always experimental and probably never worked + * correctly. It was entirely removed from the FreeType~2 sources. This + * entry is only here for historical reference. * - * 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 + * Warping only worked in 'normal' auto-hinting mode replacing it. The + * idea of the code was 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 + * much of its segments were 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. - * - * @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). - * - * The warping code can also change advance widths. Have a look at the - * `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. - * - * @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 ); - * ``` + * combinations were tried and scored. * * @since: * 2.6 |