/**************************************************************************** * * freetype.h * * FreeType high-level API and common types (specification only). * * Copyright (C) 1996-2023 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 FREETYPE_H_ #define FREETYPE_H_ #include <ft2build.h> #include FT_CONFIG_CONFIG_H #include <freetype/fttypes.h> #include <freetype/fterrors.h> FT_BEGIN_HEADER /************************************************************************** * * @section: * preamble * * @title: * Preamble * * @abstract: * What FreeType is and isn't * * @description: * FreeType is a library that provides access to glyphs in font files. It * scales the glyph images and their metrics to a requested size, and it * rasterizes the glyph images to produce pixel or subpixel alpha coverage * bitmaps. * * Note that FreeType is _not_ a text layout engine. You have to use * higher-level libraries like HarfBuzz, Pango, or ICU for that. * * Note also that FreeType does _not_ perform alpha blending or * compositing the resulting bitmaps or pixmaps by itself. Use your * favourite graphics library (for example, Cairo or Skia) to further * process FreeType's output. * */ /************************************************************************** * * @section: * header_inclusion * * @title: * FreeType's header inclusion scheme * * @abstract: * How client applications should include FreeType header files. * * @description: * To be as flexible as possible (and for historical reasons), you must * load file `ft2build.h` first before other header files, for example * * ``` * #include <ft2build.h> * * #include <freetype/freetype.h> * #include <freetype/ftoutln.h> * ``` */ /************************************************************************** * * @section: * user_allocation * * @title: * User allocation * * @abstract: * How client applications should allocate FreeType data structures. * * @description: * FreeType assumes that structures allocated by the user and passed as * arguments are zeroed out except for the actual data. In other words, * it is recommended to use `calloc` (or variants of it) instead of * `malloc` for allocation. * */ /************************************************************************** * * @section: * font_testing_macros * * @title: * Font Testing Macros * * @abstract: * Macros to test various properties of fonts. * * @description: * Macros to test the most important font properties. * * It is recommended to use these high-level macros instead of directly * testing the corresponding flags, which are scattered over various * structures. * * @order: * FT_HAS_HORIZONTAL * FT_HAS_VERTICAL * FT_HAS_KERNING * FT_HAS_FIXED_SIZES * FT_HAS_GLYPH_NAMES * FT_HAS_COLOR * FT_HAS_MULTIPLE_MASTERS * FT_HAS_SVG * FT_HAS_SBIX * FT_HAS_SBIX_OVERLAY * * FT_IS_SFNT * FT_IS_SCALABLE * FT_IS_FIXED_WIDTH * FT_IS_CID_KEYED * FT_IS_TRICKY * FT_IS_NAMED_INSTANCE * FT_IS_VARIATION * */ /************************************************************************** * * @section: * library_setup * * @title: * Library Setup * * @abstract: * Functions to start and end the usage of the FreeType library. * * @description: * Functions to start and end the usage of the FreeType library. * * Note that @FT_Library_Version and @FREETYPE_XXX are of limited use * because even a new release of FreeType with only documentation * changes increases the version number. * * @order: * FT_Library * FT_Init_FreeType * FT_Done_FreeType * * FT_Library_Version * FREETYPE_XXX * */ /************************************************************************** * * @section: * face_creation * * @title: * Face Creation * * @abstract: * Functions to manage fonts. * * @description: * The functions and structures collected in this section operate on * fonts globally. * * @order: * FT_Face * FT_FaceRec * FT_FACE_FLAG_XXX * FT_STYLE_FLAG_XXX * * FT_New_Face * FT_Done_Face * FT_Reference_Face * FT_New_Memory_Face * FT_Face_Properties * FT_Open_Face * FT_Open_Args * FT_OPEN_XXX * FT_Parameter * FT_Attach_File * FT_Attach_Stream * */ /************************************************************************** * * @section: * sizing_and_scaling * * @title: * Sizing and Scaling * * @abstract: * Functions to manage font sizes. * * @description: * The functions and structures collected in this section are related to * selecting and manipulating the size of a font globally. * * @order: * FT_Size * FT_SizeRec * FT_Size_Metrics * * FT_Bitmap_Size * * FT_Set_Char_Size * FT_Set_Pixel_Sizes * FT_Request_Size * FT_Select_Size * FT_Size_Request_Type * FT_Size_RequestRec * FT_Size_Request * * FT_Set_Transform * FT_Get_Transform * */ /************************************************************************** * * @section: * glyph_retrieval * * @title: * Glyph Retrieval * * @abstract: * Functions to manage glyphs. * * @description: * The functions and structures collected in this section operate on * single glyphs, of which @FT_Load_Glyph is most important. * * @order: * FT_GlyphSlot * FT_GlyphSlotRec * FT_Glyph_Metrics * * FT_Load_Glyph * FT_LOAD_XXX * FT_LOAD_TARGET_MODE * FT_LOAD_TARGET_XXX * * FT_Render_Glyph * FT_Render_Mode * FT_Get_Kerning * FT_Kerning_Mode * FT_Get_Track_Kerning * */ /************************************************************************** * * @section: * character_mapping * * @title: * Character Mapping * * @abstract: * Functions to manage character-to-glyph maps. * * @description: * This section holds functions and structures that are related to * mapping character input codes to glyph indices. * * Note that for many scripts the simplistic approach used by FreeType * of mapping a single character to a single glyph is not valid or * possible! In general, a higher-level library like HarfBuzz or ICU * should be used for handling text strings. * * @order: * FT_CharMap * FT_CharMapRec * FT_Encoding * FT_ENC_TAG * * FT_Select_Charmap * FT_Set_Charmap * FT_Get_Charmap_Index * * FT_Get_Char_Index * FT_Get_First_Char * FT_Get_Next_Char * FT_Load_Char * */ /************************************************************************** * * @section: * information_retrieval * * @title: * Information Retrieval * * @abstract: * Functions to retrieve font and glyph information. * * @description: * Functions to retrieve font and glyph information. Only some very * basic data is covered; see also the chapter on the format-specific * API for more. * * * @order: * FT_Get_Name_Index * FT_Get_Glyph_Name * FT_Get_Postscript_Name * FT_Get_FSType_Flags * FT_FSTYPE_XXX * FT_Get_SubGlyph_Info * FT_SUBGLYPH_FLAG_XXX * */ /************************************************************************** * * @section: * other_api_data * * @title: * Other API Data * * @abstract: * Other structures, enumerations, and macros. * * @description: * Other structures, enumerations, and macros. Deprecated functions are * also listed here. * * @order: * FT_Face_Internal * FT_Size_Internal * FT_Slot_Internal * * FT_SubGlyph * * FT_HAS_FAST_GLYPHS * FT_Face_CheckTrueTypePatents * FT_Face_SetUnpatentedHinting * */ /*************************************************************************/ /*************************************************************************/ /* */ /* B A S I C T Y P E S */ /* */ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @struct: * FT_Glyph_Metrics * * @description: * A structure to model the metrics of a single glyph. The values are * expressed in 26.6 fractional pixel format; if the flag * @FT_LOAD_NO_SCALE has been used while loading the glyph, values are * expressed in font units instead. * * @fields: * width :: * The glyph's width. * * height :: * The glyph's height. * * horiBearingX :: * Left side bearing for horizontal layout. * * horiBearingY :: * Top side bearing for horizontal layout. * * horiAdvance :: * Advance width for horizontal layout. * * vertBearingX :: * Left side bearing for vertical layout. * * vertBearingY :: * Top side bearing for vertical layout. Larger positive values mean * further below the vertical glyph origin. * * vertAdvance :: * Advance height for vertical layout. Positive values mean the glyph * has a positive advance downward. * * @note: * If not disabled with @FT_LOAD_NO_HINTING, the values represent * dimensions of the hinted glyph (in case hinting is applicable). * * Stroking a glyph with an outside border does not increase * `horiAdvance` or `vertAdvance`; you have to manually adjust these * values to account for the added width and height. * * FreeType doesn't use the 'VORG' table data for CFF fonts because it * doesn't have an interface to quickly retrieve the glyph height. The * y~coordinate of the vertical origin can be simply computed as * `vertBearingY + height` after loading a glyph. */ FT_Glyph_Metrics; /************************************************************************** * * @section: * sizing_and_scaling * */ /************************************************************************** * * @struct: * FT_Bitmap_Size * * @description: * This structure models the metrics of a bitmap strike (i.e., a set of * glyphs for a given point size and resolution) in a bitmap font. It is * used for the `available_sizes` field of @FT_Face. * * @fields: * height :: * The vertical distance, in pixels, between two consecutive baselines. * It is always positive. * * width :: * The average width, in pixels, of all glyphs in the strike. * * size :: * The nominal size of the strike in 26.6 fractional points. This * field is not very useful. * * x_ppem :: * The horizontal ppem (nominal width) in 26.6 fractional pixels. * * y_ppem :: * The vertical ppem (nominal height) in 26.6 fractional pixels. * * @note: * Windows FNT: * The nominal size given in a FNT font is not reliable. If the driver * finds it incorrect, it sets `size` to some calculated values, and * `x_ppem` and `y_ppem` to the pixel width and height given in the * font, respectively. * * TrueType embedded bitmaps: * `size`, `width`, and `height` values are not contained in the bitmap * strike itself. They are computed from the global font parameters. */ FT_Bitmap_Size; /*************************************************************************/ /*************************************************************************/ /* */ /* O B J E C T C L A S S E S */ /* */ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * @section: * library_setup * */ /************************************************************************** * * @type: * FT_Library * * @description: * A handle to a FreeType library instance. Each 'library' is completely * independent from the others; it is the 'root' of a set of objects like * fonts, faces, sizes, etc. * * It also embeds a memory manager (see @FT_Memory), as well as a * scan-line converter object (see @FT_Raster). * * [Since 2.5.6] In multi-threaded applications it is easiest to use one * `FT_Library` object per thread. In case this is too cumbersome, a * single `FT_Library` object across threads is possible also, as long as * a mutex lock is used around @FT_New_Face and @FT_Done_Face. * * @note: * Library objects are normally created by @FT_Init_FreeType, and * destroyed with @FT_Done_FreeType. If you need reference-counting * (cf. @FT_Reference_Library), use @FT_New_Library and @FT_Done_Library. */ FT_Library; /************************************************************************** * * @section: * module_management * */ /************************************************************************** * * @type: * FT_Module * * @description: * A handle to a given FreeType module object. A module can be a font * driver, a renderer, or anything else that provides services to the * former. */ FT_Module; /************************************************************************** * * @type: * FT_Driver * * @description: * A handle to a given FreeType font driver object. A font driver is a * module capable of creating faces from font files. */ FT_Driver; /************************************************************************** * * @type: * FT_Renderer * * @description: * A handle to a given FreeType renderer. A renderer is a module in * charge of converting a glyph's outline image to a bitmap. It supports * a single glyph image format, and one or more target surface depths. */ FT_Renderer; /************************************************************************** * * @section: * face_creation * */ /************************************************************************** * * @type: * FT_Face * * @description: * A handle to a typographic face object. A face object models a given * typeface, in a given style. * * @note: * A face object also owns a single @FT_GlyphSlot object, as well as one * or more @FT_Size objects. * * Use @FT_New_Face or @FT_Open_Face to create a new face object from a * given filepath or a custom input stream. * * Use @FT_Done_Face to destroy it (along with its slot and sizes). * * An `FT_Face` object can only be safely used from one thread at a time. * Similarly, creation and destruction of `FT_Face` with the same * @FT_Library object can only be done from one thread at a time. On the * other hand, functions like @FT_Load_Glyph and its siblings are * thread-safe and do not need the lock to be held as long as the same * `FT_Face` object is not used from multiple threads at the same time. * * @also: * See @FT_FaceRec for the publicly accessible fields of a given face * object. */ FT_Face; /************************************************************************** * * @section: * sizing_and_scaling * */ /************************************************************************** * * @type: * FT_Size * * @description: * A handle to an object that models a face scaled to a given character * size. * * @note: * An @FT_Face has one _active_ `FT_Size` object that is used by * functions like @FT_Load_Glyph to determine the scaling transformation * that in turn is used to load and hint glyphs and metrics. * * A newly created `FT_Size` object contains only meaningless zero values. * You must use @FT_Set_Char_Size, @FT_Set_Pixel_Sizes, @FT_Request_Size * or even @FT_Select_Size to change the content (i.e., the scaling * values) of the active `FT_Size`. Otherwise, the scaling and hinting * will not be performed. * * You can use @FT_New_Size to create additional size objects for a given * @FT_Face, but they won't be used by other functions until you activate * it through @FT_Activate_Size. Only one size can be activated at any * given time per face. * * @also: * See @FT_SizeRec for the publicly accessible fields of a given size * object. */ FT_Size; /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @type: * FT_GlyphSlot * * @description: * A handle to a given 'glyph slot'. A slot is a container that can hold * any of the glyphs contained in its parent face. * * In other words, each time you call @FT_Load_Glyph or @FT_Load_Char, * the slot's content is erased by the new glyph data, i.e., the glyph's * metrics, its image (bitmap or outline), and other control information. * * @also: * See @FT_GlyphSlotRec for the publicly accessible glyph fields. */ FT_GlyphSlot; /************************************************************************** * * @section: * character_mapping * */ /************************************************************************** * * @type: * FT_CharMap * * @description: * A handle to a character map (usually abbreviated to 'charmap'). A * charmap is used to translate character codes in a given encoding into * glyph indexes for its parent's face. Some font formats may provide * several charmaps per font. * * Each face object owns zero or more charmaps, but only one of them can * be 'active', providing the data used by @FT_Get_Char_Index or * @FT_Load_Char. * * The list of available charmaps in a face is available through the * `face->num_charmaps` and `face->charmaps` fields of @FT_FaceRec. * * The currently active charmap is available as `face->charmap`. You * should call @FT_Set_Charmap to change it. * * @note: * When a new face is created (either through @FT_New_Face or * @FT_Open_Face), the library looks for a Unicode charmap within the * list and automatically activates it. If there is no Unicode charmap, * FreeType doesn't set an 'active' charmap. * * @also: * See @FT_CharMapRec for the publicly accessible fields of a given * character map. */ FT_CharMap; /************************************************************************** * * @macro: * FT_ENC_TAG * * @description: * This macro converts four-letter tags into an unsigned long. It is * used to define 'encoding' identifiers (see @FT_Encoding). * * @note: * Since many 16-bit compilers don't like 32-bit enumerations, you should * redefine this macro in case of problems to something like this: * * ``` * #define FT_ENC_TAG( value, a, b, c, d ) value * ``` * * to get a simple enumeration without assigning special numbers. */ #ifndef FT_ENC_TAG #define FT_ENC_TAG( value, a, b, c, d ) … #endif /* FT_ENC_TAG */ /************************************************************************** * * @enum: * FT_Encoding * * @description: * An enumeration to specify character sets supported by charmaps. Used * in the @FT_Select_Charmap API function. * * @note: * Despite the name, this enumeration lists specific character * repertoires (i.e., charsets), and not text encoding methods (e.g., * UTF-8, UTF-16, etc.). * * Other encodings might be defined in the future. * * @values: * FT_ENCODING_NONE :: * The encoding value~0 is reserved for all formats except BDF, PCF, * and Windows FNT; see below for more information. * * FT_ENCODING_UNICODE :: * The Unicode character set. This value covers all versions of the * Unicode repertoire, including ASCII and Latin-1. Most fonts include * a Unicode charmap, but not all of them. * * For example, if you want to access Unicode value U+1F028 (and the * font contains it), use value 0x1F028 as the input value for * @FT_Get_Char_Index. * * FT_ENCODING_MS_SYMBOL :: * Microsoft Symbol encoding, used to encode mathematical symbols and * wingdings. For more information, see * 'https://www.microsoft.com/typography/otspec/recom.htm#non-standard-symbol-fonts', * 'http://www.kostis.net/charsets/symbol.htm', and * 'http://www.kostis.net/charsets/wingding.htm'. * * This encoding uses character codes from the PUA (Private Unicode * Area) in the range U+F020-U+F0FF. * * FT_ENCODING_SJIS :: * Shift JIS encoding for Japanese. More info at * 'https://en.wikipedia.org/wiki/Shift_JIS'. See note on multi-byte * encodings below. * * FT_ENCODING_PRC :: * Corresponds to encoding systems mainly for Simplified Chinese as * used in People's Republic of China (PRC). The encoding layout is * based on GB~2312 and its supersets GBK and GB~18030. * * FT_ENCODING_BIG5 :: * Corresponds to an encoding system for Traditional Chinese as used in * Taiwan and Hong Kong. * * FT_ENCODING_WANSUNG :: * Corresponds to the Korean encoding system known as Extended Wansung * (MS Windows code page 949). For more information see * 'https://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WindowsBestFit/bestfit949.txt'. * * FT_ENCODING_JOHAB :: * The Korean standard character set (KS~C 5601-1992), which * corresponds to MS Windows code page 1361. This character set * includes all possible Hangul character combinations. * * FT_ENCODING_ADOBE_LATIN_1 :: * Corresponds to a Latin-1 encoding as defined in a Type~1 PostScript * font. It is limited to 256 character codes. * * FT_ENCODING_ADOBE_STANDARD :: * Adobe Standard encoding, as found in Type~1, CFF, and OpenType/CFF * fonts. It is limited to 256 character codes. * * FT_ENCODING_ADOBE_EXPERT :: * Adobe Expert encoding, as found in Type~1, CFF, and OpenType/CFF * fonts. It is limited to 256 character codes. * * FT_ENCODING_ADOBE_CUSTOM :: * Corresponds to a custom encoding, as found in Type~1, CFF, and * OpenType/CFF fonts. It is limited to 256 character codes. * * FT_ENCODING_APPLE_ROMAN :: * Apple roman encoding. Many TrueType and OpenType fonts contain a * charmap for this 8-bit encoding, since older versions of Mac OS are * able to use it. * * FT_ENCODING_OLD_LATIN_2 :: * This value is deprecated and was neither used nor reported by * FreeType. Don't use or test for it. * * FT_ENCODING_MS_SJIS :: * Same as FT_ENCODING_SJIS. Deprecated. * * FT_ENCODING_MS_GB2312 :: * Same as FT_ENCODING_PRC. Deprecated. * * FT_ENCODING_MS_BIG5 :: * Same as FT_ENCODING_BIG5. Deprecated. * * FT_ENCODING_MS_WANSUNG :: * Same as FT_ENCODING_WANSUNG. Deprecated. * * FT_ENCODING_MS_JOHAB :: * Same as FT_ENCODING_JOHAB. Deprecated. * * @note: * When loading a font, FreeType makes a Unicode charmap active if * possible (either if the font provides such a charmap, or if FreeType * can synthesize one from PostScript glyph name dictionaries; in either * case, the charmap is tagged with `FT_ENCODING_UNICODE`). If such a * charmap is synthesized, it is placed at the first position of the * charmap array. * * All other encodings are considered legacy and tagged only if * explicitly defined in the font file. Otherwise, `FT_ENCODING_NONE` is * used. * * `FT_ENCODING_NONE` is set by the BDF and PCF drivers if the charmap is * neither Unicode nor ISO-8859-1 (otherwise it is set to * `FT_ENCODING_UNICODE`). Use @FT_Get_BDF_Charset_ID to find out which * encoding is really present. If, for example, the `cs_registry` field * is 'KOI8' and the `cs_encoding` field is 'R', the font is encoded in * KOI8-R. * * `FT_ENCODING_NONE` is always set (with a single exception) by the * winfonts driver. Use @FT_Get_WinFNT_Header and examine the `charset` * field of the @FT_WinFNT_HeaderRec structure to find out which encoding * is really present. For example, @FT_WinFNT_ID_CP1251 (204) means * Windows code page 1251 (for Russian). * * `FT_ENCODING_NONE` is set if `platform_id` is @TT_PLATFORM_MACINTOSH * and `encoding_id` is not `TT_MAC_ID_ROMAN` (otherwise it is set to * `FT_ENCODING_APPLE_ROMAN`). * * If `platform_id` is @TT_PLATFORM_MACINTOSH, use the function * @FT_Get_CMap_Language_ID to query the Mac language ID that may be * needed to be able to distinguish Apple encoding variants. See * * https://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/Readme.txt * * to get an idea how to do that. Basically, if the language ID is~0, * don't use it, otherwise subtract 1 from the language ID. Then examine * `encoding_id`. If, for example, `encoding_id` is `TT_MAC_ID_ROMAN` * and the language ID (minus~1) is `TT_MAC_LANGID_GREEK`, it is the * Greek encoding, not Roman. `TT_MAC_ID_ARABIC` with * `TT_MAC_LANGID_FARSI` means the Farsi variant of the Arabic encoding. */ FT_Encoding; /* these constants are deprecated; use the corresponding `FT_Encoding` */ /* values instead */ #define ft_encoding_none … #define ft_encoding_unicode … #define ft_encoding_symbol … #define ft_encoding_latin_1 … #define ft_encoding_latin_2 … #define ft_encoding_sjis … #define ft_encoding_gb2312 … #define ft_encoding_big5 … #define ft_encoding_wansung … #define ft_encoding_johab … #define ft_encoding_adobe_standard … #define ft_encoding_adobe_expert … #define ft_encoding_adobe_custom … #define ft_encoding_apple_roman … /************************************************************************** * * @struct: * FT_CharMapRec * * @description: * The base charmap structure. * * @fields: * face :: * A handle to the parent face object. * * encoding :: * An @FT_Encoding tag identifying the charmap. Use this with * @FT_Select_Charmap. * * platform_id :: * An ID number describing the platform for the following encoding ID. * This comes directly from the TrueType specification and gets * emulated for other formats. * * encoding_id :: * A platform-specific encoding number. This also comes from the * TrueType specification and gets emulated similarly. */ FT_CharMapRec; /*************************************************************************/ /*************************************************************************/ /* */ /* B A S E O B J E C T C L A S S E S */ /* */ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * @section: * other_api_data * */ /************************************************************************** * * @type: * FT_Face_Internal * * @description: * An opaque handle to an `FT_Face_InternalRec` structure that models the * private data of a given @FT_Face object. * * This structure might change between releases of FreeType~2 and is not * generally available to client applications. */ FT_Face_Internal; /************************************************************************** * * @section: * face_creation * */ /************************************************************************** * * @struct: * FT_FaceRec * * @description: * FreeType root face class structure. A face object models a typeface * in a font file. * * @fields: * num_faces :: * The number of faces in the font file. Some font formats can have * multiple faces in a single font file. * * face_index :: * This field holds two different values. Bits 0-15 are the index of * the face in the font file (starting with value~0). They are set * to~0 if there is only one face in the font file. * * [Since 2.6.1] Bits 16-30 are relevant to GX and OpenType variation * fonts only, holding the named instance index for the current face * index (starting with value~1; value~0 indicates font access without * a named instance). For non-variation fonts, bits 16-30 are ignored. * If we have the third named instance of face~4, say, `face_index` is * set to 0x00030004. * * Bit 31 is always zero (that is, `face_index` is always a positive * value). * * [Since 2.9] Changing the design coordinates with * @FT_Set_Var_Design_Coordinates or @FT_Set_Var_Blend_Coordinates does * not influence the named instance index value (only * @FT_Set_Named_Instance does that). * * face_flags :: * A set of bit flags that give important information about the face; * see @FT_FACE_FLAG_XXX for the details. * * style_flags :: * The lower 16~bits contain a set of bit flags indicating the style of * the face; see @FT_STYLE_FLAG_XXX for the details. * * [Since 2.6.1] Bits 16-30 hold the number of named instances * available for the current face if we have a GX or OpenType variation * (sub)font. Bit 31 is always zero (that is, `style_flags` is always * a positive value). Note that a variation font has always at least * one named instance, namely the default instance. * * num_glyphs :: * The number of glyphs in the face. If the face is scalable and has * sbits (see `num_fixed_sizes`), it is set to the number of outline * glyphs. * * For CID-keyed fonts (not in an SFNT wrapper) this value gives the * highest CID used in the font. * * family_name :: * The face's family name. This is an ASCII string, usually in * English, that describes the typeface's family (like 'Times New * Roman', 'Bodoni', 'Garamond', etc). This is a least common * denominator used to list fonts. Some formats (TrueType & OpenType) * provide localized and Unicode versions of this string. Applications * should use the format-specific interface to access them. Can be * `NULL` (e.g., in fonts embedded in a PDF file). * * In case the font doesn't provide a specific family name entry, * FreeType tries to synthesize one, deriving it from other name * entries. * * style_name :: * The face's style name. This is an ASCII string, usually in English, * that describes the typeface's style (like 'Italic', 'Bold', * 'Condensed', etc). Not all font formats provide a style name, so * this field is optional, and can be set to `NULL`. As for * `family_name`, some formats provide localized and Unicode versions * of this string. Applications should use the format-specific * interface to access them. * * num_fixed_sizes :: * The number of bitmap strikes in the face. Even if the face is * scalable, there might still be bitmap strikes, which are called * 'sbits' in that case. * * available_sizes :: * An array of @FT_Bitmap_Size for all bitmap strikes in the face. It * is set to `NULL` if there is no bitmap strike. * * Note that FreeType tries to sanitize the strike data since they are * sometimes sloppy or incorrect, but this can easily fail. * * num_charmaps :: * The number of charmaps in the face. * * charmaps :: * An array of the charmaps of the face. * * generic :: * A field reserved for client uses. See the @FT_Generic type * description. * * bbox :: * The font bounding box. Coordinates are expressed in font units (see * `units_per_EM`). The box is large enough to contain any glyph from * the font. Thus, `bbox.yMax` can be seen as the 'maximum ascender', * and `bbox.yMin` as the 'minimum descender'. Only relevant for * scalable formats. * * Note that the bounding box might be off by (at least) one pixel for * hinted fonts. See @FT_Size_Metrics for further discussion. * * Note that the bounding box does not vary in OpenType variation fonts * and should only be used in relation to the default instance. * * units_per_EM :: * The number of font units per EM square for this face. This is * typically 2048 for TrueType fonts, and 1000 for Type~1 fonts. Only * relevant for scalable formats. * * ascender :: * The typographic ascender of the face, expressed in font units. For * font formats not having this information, it is set to `bbox.yMax`. * Only relevant for scalable formats. * * descender :: * The typographic descender of the face, expressed in font units. For * font formats not having this information, it is set to `bbox.yMin`. * Note that this field is negative for values below the baseline. * Only relevant for scalable formats. * * height :: * This value is the vertical distance between two consecutive * baselines, expressed in font units. It is always positive. Only * relevant for scalable formats. * * If you want the global glyph height, use `ascender - descender`. * * max_advance_width :: * The maximum advance width, in font units, for all glyphs in this * face. This can be used to make word wrapping computations faster. * Only relevant for scalable formats. * * max_advance_height :: * The maximum advance height, in font units, for all glyphs in this * face. This is only relevant for vertical layouts, and is set to * `height` for fonts that do not provide vertical metrics. Only * relevant for scalable formats. * * underline_position :: * The position, in font units, of the underline line for this face. * It is the center of the underlining stem. Only relevant for * scalable formats. * * underline_thickness :: * The thickness, in font units, of the underline for this face. Only * relevant for scalable formats. * * glyph :: * The face's associated glyph slot(s). * * size :: * The current active size for this face. * * charmap :: * The current active charmap for this face. * * @note: * Fields may be changed after a call to @FT_Attach_File or * @FT_Attach_Stream. * * For an OpenType variation font, the values of the following fields can * change after a call to @FT_Set_Var_Design_Coordinates (and friends) if * the font contains an 'MVAR' table: `ascender`, `descender`, `height`, * `underline_position`, and `underline_thickness`. * * Especially for TrueType fonts see also the documentation for * @FT_Size_Metrics. */ FT_FaceRec; /************************************************************************** * * @enum: * FT_FACE_FLAG_XXX * * @description: * A list of bit flags used in the `face_flags` field of the @FT_FaceRec * structure. They inform client applications of properties of the * corresponding face. * * @values: * FT_FACE_FLAG_SCALABLE :: * The face contains outline glyphs. Note that a face can contain * bitmap strikes also, i.e., a face can have both this flag and * @FT_FACE_FLAG_FIXED_SIZES set. * * FT_FACE_FLAG_FIXED_SIZES :: * The face contains bitmap strikes. See also the `num_fixed_sizes` * and `available_sizes` fields of @FT_FaceRec. * * FT_FACE_FLAG_FIXED_WIDTH :: * The face contains fixed-width characters (like Courier, Lucida, * MonoType, etc.). * * FT_FACE_FLAG_SFNT :: * The face uses the SFNT storage scheme. For now, this means TrueType * and OpenType. * * FT_FACE_FLAG_HORIZONTAL :: * The face contains horizontal glyph metrics. This should be set for * all common formats. * * FT_FACE_FLAG_VERTICAL :: * The face contains vertical glyph metrics. This is only available in * some formats, not all of them. * * FT_FACE_FLAG_KERNING :: * The face contains kerning information. If set, the kerning distance * can be retrieved using the function @FT_Get_Kerning. Otherwise the * function always returns the vector (0,0). Note that FreeType * doesn't handle kerning data from the SFNT 'GPOS' table (as present * in many OpenType fonts). * * FT_FACE_FLAG_FAST_GLYPHS :: * THIS FLAG IS DEPRECATED. DO NOT USE OR TEST IT. * * FT_FACE_FLAG_MULTIPLE_MASTERS :: * The face contains multiple masters and is capable of interpolating * between them. Supported formats are Adobe MM, TrueType GX, and * OpenType variation fonts. * * See section @multiple_masters for API details. * * FT_FACE_FLAG_GLYPH_NAMES :: * The face contains glyph names, which can be retrieved using * @FT_Get_Glyph_Name. Note that some TrueType fonts contain broken * glyph name tables. Use the function @FT_Has_PS_Glyph_Names when * needed. * * FT_FACE_FLAG_EXTERNAL_STREAM :: * Used internally by FreeType to indicate that a face's stream was * provided by the client application and should not be destroyed when * @FT_Done_Face is called. Don't read or test this flag. * * FT_FACE_FLAG_HINTER :: * The font driver has a hinting machine of its own. For example, with * TrueType fonts, it makes sense to use data from the SFNT 'gasp' * table only if the native TrueType hinting engine (with the bytecode * interpreter) is available and active. * * FT_FACE_FLAG_CID_KEYED :: * The face is CID-keyed. In that case, the face is not accessed by * glyph indices but by CID values. For subsetted CID-keyed fonts this * has the consequence that not all index values are a valid argument * to @FT_Load_Glyph. Only the CID values for which corresponding * glyphs in the subsetted font exist make `FT_Load_Glyph` return * successfully; in all other cases you get an * `FT_Err_Invalid_Argument` error. * * Note that CID-keyed fonts that are in an SFNT wrapper (that is, all * OpenType/CFF fonts) don't have this flag set since the glyphs are * accessed in the normal way (using contiguous indices); the * 'CID-ness' isn't visible to the application. * * FT_FACE_FLAG_TRICKY :: * The face is 'tricky', that is, it always needs the font format's * native hinting engine to get a reasonable result. A typical example * is the old Chinese font `mingli.ttf` (but not `mingliu.ttc`) that * uses TrueType bytecode instructions to move and scale all of its * subglyphs. * * It is not possible to auto-hint such fonts using * @FT_LOAD_FORCE_AUTOHINT; it will also ignore @FT_LOAD_NO_HINTING. * You have to set both @FT_LOAD_NO_HINTING and @FT_LOAD_NO_AUTOHINT to * really disable hinting; however, you probably never want this except * for demonstration purposes. * * Currently, there are about a dozen TrueType fonts in the list of * tricky fonts; they are hard-coded in file `ttobjs.c`. * * FT_FACE_FLAG_COLOR :: * [Since 2.5.1] The face has color glyph tables. See @FT_LOAD_COLOR * for more information. * * FT_FACE_FLAG_VARIATION :: * [Since 2.9] Set if the current face (or named instance) has been * altered with @FT_Set_MM_Design_Coordinates, * @FT_Set_Var_Design_Coordinates, @FT_Set_Var_Blend_Coordinates, or * @FT_Set_MM_WeightVector to select a non-default instance. * * FT_FACE_FLAG_SVG :: * [Since 2.12] The face has an 'SVG~' OpenType table. * * FT_FACE_FLAG_SBIX :: * [Since 2.12] The face has an 'sbix' OpenType table *and* outlines. * For such fonts, @FT_FACE_FLAG_SCALABLE is not set by default to * retain backward compatibility. * * FT_FACE_FLAG_SBIX_OVERLAY :: * [Since 2.12] The face has an 'sbix' OpenType table where outlines * should be drawn on top of bitmap strikes. * */ #define FT_FACE_FLAG_SCALABLE … #define FT_FACE_FLAG_FIXED_SIZES … #define FT_FACE_FLAG_FIXED_WIDTH … #define FT_FACE_FLAG_SFNT … #define FT_FACE_FLAG_HORIZONTAL … #define FT_FACE_FLAG_VERTICAL … #define FT_FACE_FLAG_KERNING … #define FT_FACE_FLAG_FAST_GLYPHS … #define FT_FACE_FLAG_MULTIPLE_MASTERS … #define FT_FACE_FLAG_GLYPH_NAMES … #define FT_FACE_FLAG_EXTERNAL_STREAM … #define FT_FACE_FLAG_HINTER … #define FT_FACE_FLAG_CID_KEYED … #define FT_FACE_FLAG_TRICKY … #define FT_FACE_FLAG_COLOR … #define FT_FACE_FLAG_VARIATION … #define FT_FACE_FLAG_SVG … #define FT_FACE_FLAG_SBIX … #define FT_FACE_FLAG_SBIX_OVERLAY … /************************************************************************** * * @section: * font_testing_macros * */ /************************************************************************** * * @macro: * FT_HAS_HORIZONTAL * * @description: * A macro that returns true whenever a face object contains horizontal * metrics (this is true for all font formats though). * * @also: * @FT_HAS_VERTICAL can be used to check for vertical metrics. * */ #define FT_HAS_HORIZONTAL( face ) … /************************************************************************** * * @macro: * FT_HAS_VERTICAL * * @description: * A macro that returns true whenever a face object contains real * vertical metrics (and not only synthesized ones). * */ #define FT_HAS_VERTICAL( face ) … /************************************************************************** * * @macro: * FT_HAS_KERNING * * @description: * A macro that returns true whenever a face object contains kerning data * that can be accessed with @FT_Get_Kerning. * */ #define FT_HAS_KERNING( face ) … /************************************************************************** * * @macro: * FT_IS_SCALABLE * * @description: * A macro that returns true whenever a face object contains a scalable * font face (true for TrueType, Type~1, Type~42, CID, OpenType/CFF, and * PFR font formats). * */ #define FT_IS_SCALABLE( face ) … /************************************************************************** * * @macro: * FT_IS_SFNT * * @description: * A macro that returns true whenever a face object contains a font whose * format is based on the SFNT storage scheme. This usually means: * TrueType fonts, OpenType fonts, as well as SFNT-based embedded bitmap * fonts. * * If this macro is true, all functions defined in @FT_SFNT_NAMES_H and * @FT_TRUETYPE_TABLES_H are available. * */ #define FT_IS_SFNT( face ) … /************************************************************************** * * @macro: * FT_IS_FIXED_WIDTH * * @description: * A macro that returns true whenever a face object contains a font face * that contains fixed-width (or 'monospace', 'fixed-pitch', etc.) * glyphs. * */ #define FT_IS_FIXED_WIDTH( face ) … /************************************************************************** * * @macro: * FT_HAS_FIXED_SIZES * * @description: * A macro that returns true whenever a face object contains some * embedded bitmaps. See the `available_sizes` field of the @FT_FaceRec * structure. * */ #define FT_HAS_FIXED_SIZES( face ) … /************************************************************************** * * @section: * other_api_data * */ /************************************************************************** * * @macro: * FT_HAS_FAST_GLYPHS * * @description: * Deprecated. * */ #define FT_HAS_FAST_GLYPHS( face ) … /************************************************************************** * * @section: * font_testing_macros * */ /************************************************************************** * * @macro: * FT_HAS_GLYPH_NAMES * * @description: * A macro that returns true whenever a face object contains some glyph * names that can be accessed through @FT_Get_Glyph_Name. * */ #define FT_HAS_GLYPH_NAMES( face ) … /************************************************************************** * * @macro: * FT_HAS_MULTIPLE_MASTERS * * @description: * A macro that returns true whenever a face object contains some * multiple masters. The functions provided by @FT_MULTIPLE_MASTERS_H * are then available to choose the exact design you want. * */ #define FT_HAS_MULTIPLE_MASTERS( face ) … /************************************************************************** * * @macro: * FT_IS_NAMED_INSTANCE * * @description: * A macro that returns true whenever a face object is a named instance * of a GX or OpenType variation font. * * [Since 2.9] Changing the design coordinates with * @FT_Set_Var_Design_Coordinates or @FT_Set_Var_Blend_Coordinates does * not influence the return value of this macro (only * @FT_Set_Named_Instance does that). * * @since: * 2.7 * */ #define FT_IS_NAMED_INSTANCE( face ) … /************************************************************************** * * @macro: * FT_IS_VARIATION * * @description: * A macro that returns true whenever a face object has been altered by * @FT_Set_MM_Design_Coordinates, @FT_Set_Var_Design_Coordinates, * @FT_Set_Var_Blend_Coordinates, or @FT_Set_MM_WeightVector. * * @since: * 2.9 * */ #define FT_IS_VARIATION( face ) … /************************************************************************** * * @macro: * FT_IS_CID_KEYED * * @description: * A macro that returns true whenever a face object contains a CID-keyed * font. See the discussion of @FT_FACE_FLAG_CID_KEYED for more details. * * If this macro is true, all functions defined in @FT_CID_H are * available. * */ #define FT_IS_CID_KEYED( face ) … /************************************************************************** * * @macro: * FT_IS_TRICKY * * @description: * A macro that returns true whenever a face represents a 'tricky' font. * See the discussion of @FT_FACE_FLAG_TRICKY for more details. * */ #define FT_IS_TRICKY( face ) … /************************************************************************** * * @macro: * FT_HAS_COLOR * * @description: * A macro that returns true whenever a face object contains tables for * color glyphs. * * @since: * 2.5.1 * */ #define FT_HAS_COLOR( face ) … /************************************************************************** * * @macro: * FT_HAS_SVG * * @description: * A macro that returns true whenever a face object contains an 'SVG~' * OpenType table. * * @since: * 2.12 */ #define FT_HAS_SVG( face ) … /************************************************************************** * * @macro: * FT_HAS_SBIX * * @description: * A macro that returns true whenever a face object contains an 'sbix' * OpenType table *and* outline glyphs. * * Currently, FreeType only supports bitmap glyphs in PNG format for this * table (i.e., JPEG and TIFF formats are unsupported, as are * Apple-specific formats not part of the OpenType specification). * * @note: * For backward compatibility, a font with an 'sbix' table is treated as * a bitmap-only face. Using @FT_Open_Face with * @FT_PARAM_TAG_IGNORE_SBIX, an application can switch off 'sbix' * handling so that the face is treated as an ordinary outline font with * scalable outlines. * * Here is some pseudo code that roughly illustrates how to implement * 'sbix' handling according to the OpenType specification. * * ``` * if ( FT_HAS_SBIX( face ) ) * { * // open font as a scalable one without sbix handling * FT_Face face2; * FT_Parameter param = { FT_PARAM_TAG_IGNORE_SBIX, NULL }; * FT_Open_Args args = { FT_OPEN_PARAMS | ..., * ..., * 1, ¶m }; * * * FT_Open_Face( library, &args, 0, &face2 ); * * <sort `face->available_size` as necessary into * `preferred_sizes`[*]> * * for ( i = 0; i < face->num_fixed_sizes; i++ ) * { * size = preferred_sizes[i].size; * * error = FT_Set_Pixel_Sizes( face, size, size ); * <error handling omitted> * * // check whether we have a glyph in a bitmap strike * error = FT_Load_Glyph( face, * glyph_index, * FT_LOAD_SBITS_ONLY | * FT_LOAD_BITMAP_METRICS_ONLY ); * if ( error == FT_Err_Invalid_Argument ) * continue; * else if ( error ) * <other error handling omitted> * else * break; * } * * if ( i != face->num_fixed_sizes ) * <load embedded bitmap with `FT_Load_Glyph`, * scale it, display it, etc.> * * if ( i == face->num_fixed_sizes || * FT_HAS_SBIX_OVERLAY( face ) ) * <use `face2` to load outline glyph with `FT_Load_Glyph`, * scale it, display it on top of the bitmap, etc.> * } * ``` * * [*] Assuming a target value of 400dpi and available strike sizes 100, * 200, 300, and 400dpi, a possible order might be [400, 200, 300, 100]: * scaling 200dpi to 400dpi usually gives better results than scaling * 300dpi to 400dpi; it is also much faster. However, scaling 100dpi to * 400dpi can yield a too pixelated result, thus the preference might be * 300dpi over 100dpi. * * @since: * 2.12 */ #define FT_HAS_SBIX( face ) … /************************************************************************** * * @macro: * FT_HAS_SBIX_OVERLAY * * @description: * A macro that returns true whenever a face object contains an 'sbix' * OpenType table with bit~1 in its `flags` field set, instructing the * application to overlay the bitmap strike with the corresponding * outline glyph. See @FT_HAS_SBIX for pseudo code how to use it. * * @since: * 2.12 */ #define FT_HAS_SBIX_OVERLAY( face ) … /************************************************************************** * * @section: * face_creation * */ /************************************************************************** * * @enum: * FT_STYLE_FLAG_XXX * * @description: * A list of bit flags to indicate the style of a given face. These are * used in the `style_flags` field of @FT_FaceRec. * * @values: * FT_STYLE_FLAG_ITALIC :: * The face style is italic or oblique. * * FT_STYLE_FLAG_BOLD :: * The face is bold. * * @note: * The style information as provided by FreeType is very basic. More * details are beyond the scope and should be done on a higher level (for * example, by analyzing various fields of the 'OS/2' table in SFNT based * fonts). */ #define FT_STYLE_FLAG_ITALIC … #define FT_STYLE_FLAG_BOLD … /************************************************************************** * * @section: * other_api_data * */ /************************************************************************** * * @type: * FT_Size_Internal * * @description: * An opaque handle to an `FT_Size_InternalRec` structure, used to model * private data of a given @FT_Size object. */ FT_Size_Internal; /************************************************************************** * * @section: * sizing_and_scaling * */ /************************************************************************** * * @struct: * FT_Size_Metrics * * @description: * The size metrics structure gives the metrics of a size object. * * @fields: * x_ppem :: * The width of the scaled EM square in pixels, hence the term 'ppem' * (pixels per EM). It is also referred to as 'nominal width'. * * y_ppem :: * The height of the scaled EM square in pixels, hence the term 'ppem' * (pixels per EM). It is also referred to as 'nominal height'. * * x_scale :: * A 16.16 fractional scaling value to convert horizontal metrics from * font units to 26.6 fractional pixels. Only relevant for scalable * font formats. * * y_scale :: * A 16.16 fractional scaling value to convert vertical metrics from * font units to 26.6 fractional pixels. Only relevant for scalable * font formats. * * ascender :: * The ascender in 26.6 fractional pixels, rounded up to an integer * value. See @FT_FaceRec for the details. * * descender :: * The descender in 26.6 fractional pixels, rounded down to an integer * value. See @FT_FaceRec for the details. * * height :: * The height in 26.6 fractional pixels, rounded to an integer value. * See @FT_FaceRec for the details. * * max_advance :: * The maximum advance width in 26.6 fractional pixels, rounded to an * integer value. See @FT_FaceRec for the details. * * @note: * The scaling values, if relevant, are determined first during a size * changing operation. The remaining fields are then set by the driver. * For scalable formats, they are usually set to scaled values of the * corresponding fields in @FT_FaceRec. Some values like ascender or * descender are rounded for historical reasons; more precise values (for * outline fonts) can be derived by scaling the corresponding @FT_FaceRec * values manually, with code similar to the following. * * ``` * scaled_ascender = FT_MulFix( face->ascender, * size_metrics->y_scale ); * ``` * * Note that due to glyph hinting and the selected rendering mode these * values are usually not exact; consequently, they must be treated as * unreliable with an error margin of at least one pixel! * * Indeed, the only way to get the exact metrics is to render _all_ * glyphs. As this would be a definite performance hit, it is up to * client applications to perform such computations. * * The `FT_Size_Metrics` structure is valid for bitmap fonts also. * * * **TrueType fonts with native bytecode hinting** * * All applications that handle TrueType fonts with native hinting must * be aware that TTFs expect different rounding of vertical font * dimensions. The application has to cater for this, especially if it * wants to rely on a TTF's vertical data (for example, to properly align * box characters vertically). * * Only the application knows _in advance_ that it is going to use native * hinting for TTFs! FreeType, on the other hand, selects the hinting * mode not at the time of creating an @FT_Size object but much later, * namely while calling @FT_Load_Glyph. * * Here is some pseudo code that illustrates a possible solution. * * ``` * font_format = FT_Get_Font_Format( face ); * * if ( !strcmp( font_format, "TrueType" ) && * do_native_bytecode_hinting ) * { * ascender = ROUND( FT_MulFix( face->ascender, * size_metrics->y_scale ) ); * descender = ROUND( FT_MulFix( face->descender, * size_metrics->y_scale ) ); * } * else * { * ascender = size_metrics->ascender; * descender = size_metrics->descender; * } * * height = size_metrics->height; * max_advance = size_metrics->max_advance; * ``` */ FT_Size_Metrics; /************************************************************************** * * @struct: * FT_SizeRec * * @description: * FreeType root size class structure. A size object models a face * object at a given size. * * @fields: * face :: * Handle to the parent face object. * * generic :: * A typeless pointer, unused by the FreeType library or any of its * drivers. It can be used by client applications to link their own * data to each size object. * * metrics :: * Metrics for this size object. This field is read-only. */ FT_SizeRec; /************************************************************************** * * @section: * other_api_data * */ /************************************************************************** * * @struct: * FT_SubGlyph * * @description: * The subglyph structure is an internal object used to describe * subglyphs (for example, in the case of composites). * * @note: * The subglyph implementation is not part of the high-level API, hence * the forward structure declaration. * * You can however retrieve subglyph information with * @FT_Get_SubGlyph_Info. */ FT_SubGlyph; /************************************************************************** * * @type: * FT_Slot_Internal * * @description: * An opaque handle to an `FT_Slot_InternalRec` structure, used to model * private data of a given @FT_GlyphSlot object. */ FT_Slot_Internal; /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @struct: * FT_GlyphSlotRec * * @description: * FreeType root glyph slot class structure. A glyph slot is a container * where individual glyphs can be loaded, be they in outline or bitmap * format. * * @fields: * library :: * A handle to the FreeType library instance this slot belongs to. * * face :: * A handle to the parent face object. * * next :: * In some cases (like some font tools), several glyph slots per face * object can be a good thing. As this is rare, the glyph slots are * listed through a direct, single-linked list using its `next` field. * * glyph_index :: * [Since 2.10] The glyph index passed as an argument to @FT_Load_Glyph * while initializing the glyph slot. * * generic :: * A typeless pointer unused by the FreeType library or any of its * drivers. It can be used by client applications to link their own * data to each glyph slot object. * * metrics :: * The metrics of the last loaded glyph in the slot. The returned * values depend on the last load flags (see the @FT_Load_Glyph API * function) and can be expressed either in 26.6 fractional pixels or * font units. * * Note that even when the glyph image is transformed, the metrics are * not. * * linearHoriAdvance :: * The advance width of the unhinted glyph. Its value is expressed in * 16.16 fractional pixels, unless @FT_LOAD_LINEAR_DESIGN is set when * loading the glyph. This field can be important to perform correct * WYSIWYG layout. Only relevant for scalable glyphs. * * linearVertAdvance :: * The advance height of the unhinted glyph. Its value is expressed in * 16.16 fractional pixels, unless @FT_LOAD_LINEAR_DESIGN is set when * loading the glyph. This field can be important to perform correct * WYSIWYG layout. Only relevant for scalable glyphs. * * advance :: * This shorthand is, depending on @FT_LOAD_IGNORE_TRANSFORM, the * transformed (hinted) advance width for the glyph, in 26.6 fractional * pixel format. As specified with @FT_LOAD_VERTICAL_LAYOUT, it uses * either the `horiAdvance` or the `vertAdvance` value of `metrics` * field. * * format :: * This field indicates the format of the image contained in the glyph * slot. Typically @FT_GLYPH_FORMAT_BITMAP, @FT_GLYPH_FORMAT_OUTLINE, * or @FT_GLYPH_FORMAT_COMPOSITE, but other values are possible. * * bitmap :: * This field is used as a bitmap descriptor. Note that the address * and content of the bitmap buffer can change between calls of * @FT_Load_Glyph and a few other functions. * * bitmap_left :: * The bitmap's left bearing expressed in integer pixels. * * bitmap_top :: * The bitmap's top bearing expressed in integer pixels. This is the * distance from the baseline to the top-most glyph scanline, upwards * y~coordinates being **positive**. * * outline :: * The outline descriptor for the current glyph image if its format is * @FT_GLYPH_FORMAT_OUTLINE. Once a glyph is loaded, `outline` can be * transformed, distorted, emboldened, etc. However, it must not be * freed. * * [Since 2.10.1] If @FT_LOAD_NO_SCALE is set, outline coordinates of * OpenType variation fonts for a selected instance are internally * handled as 26.6 fractional font units but returned as (rounded) * integers, as expected. To get unrounded font units, don't use * @FT_LOAD_NO_SCALE but load the glyph with @FT_LOAD_NO_HINTING and * scale it, using the font's `units_per_EM` value as the ppem. * * num_subglyphs :: * The number of subglyphs in a composite glyph. This field is only * valid for the composite glyph format that should normally only be * loaded with the @FT_LOAD_NO_RECURSE flag. * * subglyphs :: * An array of subglyph descriptors for composite glyphs. There are * `num_subglyphs` elements in there. Currently internal to FreeType. * * control_data :: * Certain font drivers can also return the control data for a given * glyph image (e.g. TrueType bytecode, Type~1 charstrings, etc.). * This field is a pointer to such data; it is currently internal to * FreeType. * * control_len :: * This is the length in bytes of the control data. Currently internal * to FreeType. * * other :: * Reserved. * * lsb_delta :: * The difference between hinted and unhinted left side bearing while * auto-hinting is active. Zero otherwise. * * rsb_delta :: * The difference between hinted and unhinted right side bearing while * auto-hinting is active. Zero otherwise. * * @note: * If @FT_Load_Glyph is called with default flags (see @FT_LOAD_DEFAULT) * the glyph image is loaded in the glyph slot in its native format * (e.g., an outline glyph for TrueType and Type~1 formats). [Since 2.9] * The prospective bitmap metrics are calculated according to * @FT_LOAD_TARGET_XXX and other flags even for the outline glyph, even * if @FT_LOAD_RENDER is not set. * * This image can later be converted into a bitmap by calling * @FT_Render_Glyph. This function searches the current renderer for the * native image's format, then invokes it. * * The renderer is in charge of transforming the native image through the * slot's face transformation fields, then converting it into a bitmap * that is returned in `slot->bitmap`. * * Note that `slot->bitmap_left` and `slot->bitmap_top` are also used to * specify the position of the bitmap relative to the current pen * position (e.g., coordinates (0,0) on the baseline). Of course, * `slot->format` is also changed to @FT_GLYPH_FORMAT_BITMAP. * * Here is a small pseudo code fragment that shows how to use `lsb_delta` * and `rsb_delta` to do fractional positioning of glyphs: * * ``` * FT_GlyphSlot slot = face->glyph; * FT_Pos origin_x = 0; * * * for all glyphs do * <load glyph with `FT_Load_Glyph'> * * FT_Outline_Translate( slot->outline, origin_x & 63, 0 ); * * <save glyph image, or render glyph, or ...> * * <compute kern between current and next glyph * and add it to `origin_x'> * * origin_x += slot->advance.x; * origin_x += slot->lsb_delta - slot->rsb_delta; * endfor * ``` * * Here is another small pseudo code fragment that shows how to use * `lsb_delta` and `rsb_delta` to improve integer positioning of glyphs: * * ``` * FT_GlyphSlot slot = face->glyph; * FT_Pos origin_x = 0; * FT_Pos prev_rsb_delta = 0; * * * for all glyphs do * <compute kern between current and previous glyph * and add it to `origin_x'> * * <load glyph with `FT_Load_Glyph'> * * if ( prev_rsb_delta - slot->lsb_delta > 32 ) * origin_x -= 64; * else if ( prev_rsb_delta - slot->lsb_delta < -31 ) * origin_x += 64; * * prev_rsb_delta = slot->rsb_delta; * * <save glyph image, or render glyph, or ...> * * origin_x += slot->advance.x; * endfor * ``` * * If you use strong auto-hinting, you **must** apply these delta values! * Otherwise you will experience far too large inter-glyph spacing at * small rendering sizes in most cases. Note that it doesn't harm to use * the above code for other hinting modes also, since the delta values * are zero then. */ FT_GlyphSlotRec; /*************************************************************************/ /*************************************************************************/ /* */ /* F U N C T I O N S */ /* */ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * @section: * library_setup * */ /************************************************************************** * * @function: * FT_Init_FreeType * * @description: * Initialize a new FreeType library object. The set of modules that are * registered by this function is determined at build time. * * @output: * alibrary :: * A handle to a new library object. * * @return: * FreeType error code. 0~means success. * * @note: * In case you want to provide your own memory allocating routines, use * @FT_New_Library instead, followed by a call to @FT_Add_Default_Modules * (or a series of calls to @FT_Add_Module) and * @FT_Set_Default_Properties. * * See the documentation of @FT_Library and @FT_Face for multi-threading * issues. * * If you need reference-counting (cf. @FT_Reference_Library), use * @FT_New_Library and @FT_Done_Library. * * If compilation option `FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES` is * set, this function reads the `FREETYPE_PROPERTIES` environment * variable to control driver properties. See section @properties for * more. */ FT_EXPORT( FT_Error ) FT_Init_FreeType( FT_Library *alibrary ); /************************************************************************** * * @function: * FT_Done_FreeType * * @description: * Destroy a given FreeType library object and all of its children, * including resources, drivers, faces, sizes, etc. * * @input: * library :: * A handle to the target library object. * * @return: * FreeType error code. 0~means success. */ FT_EXPORT( FT_Error ) FT_Done_FreeType( FT_Library library ); /************************************************************************** * * @section: * face_creation * */ /************************************************************************** * * @enum: * FT_OPEN_XXX * * @description: * A list of bit field constants used within the `flags` field of the * @FT_Open_Args structure. * * @values: * FT_OPEN_MEMORY :: * This is a memory-based stream. * * FT_OPEN_STREAM :: * Copy the stream from the `stream` field. * * FT_OPEN_PATHNAME :: * Create a new input stream from a C~path name. * * FT_OPEN_DRIVER :: * Use the `driver` field. * * FT_OPEN_PARAMS :: * Use the `num_params` and `params` fields. * * @note: * The `FT_OPEN_MEMORY`, `FT_OPEN_STREAM`, and `FT_OPEN_PATHNAME` flags * are mutually exclusive. */ #define FT_OPEN_MEMORY … #define FT_OPEN_STREAM … #define FT_OPEN_PATHNAME … #define FT_OPEN_DRIVER … #define FT_OPEN_PARAMS … /* these constants are deprecated; use the corresponding `FT_OPEN_XXX` */ /* values instead */ #define ft_open_memory … #define ft_open_stream … #define ft_open_pathname … #define ft_open_driver … #define ft_open_params … /************************************************************************** * * @struct: * FT_Parameter * * @description: * A simple structure to pass more or less generic parameters to * @FT_Open_Face and @FT_Face_Properties. * * @fields: * tag :: * A four-byte identification tag. * * data :: * A pointer to the parameter data. * * @note: * The ID and function of parameters are driver-specific. See section * @parameter_tags for more information. */ FT_Parameter; /************************************************************************** * * @struct: * FT_Open_Args * * @description: * A structure to indicate how to open a new font file or stream. A * pointer to such a structure can be used as a parameter for the * functions @FT_Open_Face and @FT_Attach_Stream. * * @fields: * flags :: * A set of bit flags indicating how to use the structure. * * memory_base :: * The first byte of the file in memory. * * memory_size :: * The size in bytes of the file in memory. * * pathname :: * A pointer to an 8-bit file pathname, which must be a C~string (i.e., * no null bytes except at the very end). The pointer is not owned by * FreeType. * * stream :: * A handle to a source stream object. * * driver :: * This field is exclusively used by @FT_Open_Face; it simply specifies * the font driver to use for opening the face. If set to `NULL`, * FreeType tries to load the face with each one of the drivers in its * list. * * num_params :: * The number of extra parameters. * * params :: * Extra parameters passed to the font driver when opening a new face. * * @note: * The stream type is determined by the contents of `flags`: * * If the @FT_OPEN_MEMORY bit is set, assume that this is a memory file * of `memory_size` bytes, located at `memory_address`. The data are not * copied, and the client is responsible for releasing and destroying * them _after_ the corresponding call to @FT_Done_Face. * * Otherwise, if the @FT_OPEN_STREAM bit is set, assume that a custom * input stream `stream` is used. * * Otherwise, if the @FT_OPEN_PATHNAME bit is set, assume that this is a * normal file and use `pathname` to open it. * * If none of the above bits are set or if multiple are set at the same * time, the flags are invalid and @FT_Open_Face fails. * * If the @FT_OPEN_DRIVER bit is set, @FT_Open_Face only tries to open * the file with the driver whose handler is in `driver`. * * If the @FT_OPEN_PARAMS bit is set, the parameters given by * `num_params` and `params` is used. They are ignored otherwise. * * Ideally, both the `pathname` and `params` fields should be tagged as * 'const'; this is missing for API backward compatibility. In other * words, applications should treat them as read-only. */ FT_Open_Args; /************************************************************************** * * @function: * FT_New_Face * * @description: * Call @FT_Open_Face to open a font by its pathname. * * @inout: * library :: * A handle to the library resource. * * @input: * pathname :: * A path to the font file. * * face_index :: * See @FT_Open_Face for a detailed description of this parameter. * * @output: * aface :: * A handle to a new face object. If `face_index` is greater than or * equal to zero, it must be non-`NULL`. * * @return: * FreeType error code. 0~means success. * * @note: * The `pathname` string should be recognizable as such by a standard * `fopen` call on your system; in particular, this means that `pathname` * must not contain null bytes. If that is not sufficient to address all * file name possibilities (for example, to handle wide character file * names on Windows in UTF-16 encoding) you might use @FT_Open_Face to * pass a memory array or a stream object instead. * * Use @FT_Done_Face to destroy the created @FT_Face object (along with * its slot and sizes). */ FT_EXPORT( FT_Error ) FT_New_Face( FT_Library library, const char* filepathname, FT_Long face_index, FT_Face *aface ); /************************************************************************** * * @function: * FT_New_Memory_Face * * @description: * Call @FT_Open_Face to open a font that has been loaded into memory. * * @inout: * library :: * A handle to the library resource. * * @input: * file_base :: * A pointer to the beginning of the font data. * * file_size :: * The size of the memory chunk used by the font data. * * face_index :: * See @FT_Open_Face for a detailed description of this parameter. * * @output: * aface :: * A handle to a new face object. If `face_index` is greater than or * equal to zero, it must be non-`NULL`. * * @return: * FreeType error code. 0~means success. * * @note: * You must not deallocate the memory before calling @FT_Done_Face. */ FT_EXPORT( FT_Error ) FT_New_Memory_Face( FT_Library library, const FT_Byte* file_base, FT_Long file_size, FT_Long face_index, FT_Face *aface ); /************************************************************************** * * @function: * FT_Open_Face * * @description: * Create a face object from a given resource described by @FT_Open_Args. * * @inout: * library :: * A handle to the library resource. * * @input: * args :: * A pointer to an `FT_Open_Args` structure that must be filled by the * caller. * * face_index :: * This field holds two different values. Bits 0-15 are the index of * the face in the font file (starting with value~0). Set it to~0 if * there is only one face in the font file. * * [Since 2.6.1] Bits 16-30 are relevant to GX and OpenType variation * fonts only, specifying the named instance index for the current face * index (starting with value~1; value~0 makes FreeType ignore named * instances). For non-variation fonts, bits 16-30 are ignored. * Assuming that you want to access the third named instance in face~4, * `face_index` should be set to 0x00030004. If you want to access * face~4 without variation handling, simply set `face_index` to * value~4. * * `FT_Open_Face` and its siblings can be used to quickly check whether * the font format of a given font resource is supported by FreeType. * In general, if the `face_index` argument is negative, the function's * return value is~0 if the font format is recognized, or non-zero * otherwise. The function allocates a more or less empty face handle * in `*aface` (if `aface` isn't `NULL`); the only two useful fields in * this special case are `face->num_faces` and `face->style_flags`. * For any negative value of `face_index`, `face->num_faces` gives the * number of faces within the font file. For the negative value * '-(N+1)' (with 'N' a non-negative 16-bit value), bits 16-30 in * `face->style_flags` give the number of named instances in face 'N' * if we have a variation font (or zero otherwise). After examination, * the returned @FT_Face structure should be deallocated with a call to * @FT_Done_Face. * * @output: * aface :: * A handle to a new face object. If `face_index` is greater than or * equal to zero, it must be non-`NULL`. * * @return: * FreeType error code. 0~means success. * * @note: * Unlike FreeType 1.x, this function automatically creates a glyph slot * for the face object that can be accessed directly through * `face->glyph`. * * Each new face object created with this function also owns a default * @FT_Size object, accessible as `face->size`. * * One @FT_Library instance can have multiple face objects, that is, * @FT_Open_Face and its siblings can be called multiple times using the * same `library` argument. * * See the discussion of reference counters in the description of * @FT_Reference_Face. * * If `FT_OPEN_STREAM` is set in `args->flags`, the stream in * `args->stream` is automatically closed before this function returns * any error (including `FT_Err_Invalid_Argument`). * * @example: * To loop over all faces, use code similar to the following snippet * (omitting the error handling). * * ``` * ... * FT_Face face; * FT_Long i, num_faces; * * * error = FT_Open_Face( library, args, -1, &face ); * if ( error ) { ... } * * num_faces = face->num_faces; * FT_Done_Face( face ); * * for ( i = 0; i < num_faces; i++ ) * { * ... * error = FT_Open_Face( library, args, i, &face ); * ... * FT_Done_Face( face ); * ... * } * ``` * * To loop over all valid values for `face_index`, use something similar * to the following snippet, again without error handling. The code * accesses all faces immediately (thus only a single call of * `FT_Open_Face` within the do-loop), with and without named instances. * * ``` * ... * FT_Face face; * * FT_Long num_faces = 0; * FT_Long num_instances = 0; * * FT_Long face_idx = 0; * FT_Long instance_idx = 0; * * * do * { * FT_Long id = ( instance_idx << 16 ) + face_idx; * * * error = FT_Open_Face( library, args, id, &face ); * if ( error ) { ... } * * num_faces = face->num_faces; * num_instances = face->style_flags >> 16; * * ... * * FT_Done_Face( face ); * * if ( instance_idx < num_instances ) * instance_idx++; * else * { * face_idx++; * instance_idx = 0; * } * * } while ( face_idx < num_faces ) * ``` */ FT_EXPORT( FT_Error ) FT_Open_Face( FT_Library library, const FT_Open_Args* args, FT_Long face_index, FT_Face *aface ); /************************************************************************** * * @function: * FT_Attach_File * * @description: * Call @FT_Attach_Stream to attach a file. * * @inout: * face :: * The target face object. * * @input: * filepathname :: * The pathname. * * @return: * FreeType error code. 0~means success. */ FT_EXPORT( FT_Error ) FT_Attach_File( FT_Face face, const char* filepathname ); /************************************************************************** * * @function: * FT_Attach_Stream * * @description: * 'Attach' data to a face object. Normally, this is used to read * additional information for the face object. For example, you can * attach an AFM file that comes with a Type~1 font to get the kerning * values and other metrics. * * @inout: * face :: * The target face object. * * @input: * parameters :: * A pointer to @FT_Open_Args that must be filled by the caller. * * @return: * FreeType error code. 0~means success. * * @note: * The meaning of the 'attach' (i.e., what really happens when the new * file is read) is not fixed by FreeType itself. It really depends on * the font format (and thus the font driver). * * Client applications are expected to know what they are doing when * invoking this function. Most drivers simply do not implement file or * stream attachments. */ FT_EXPORT( FT_Error ) FT_Attach_Stream( FT_Face face, const FT_Open_Args* parameters ); /************************************************************************** * * @function: * FT_Reference_Face * * @description: * A counter gets initialized to~1 at the time an @FT_Face structure is * created. This function increments the counter. @FT_Done_Face then * only destroys a face if the counter is~1, otherwise it simply * decrements the counter. * * This function helps in managing life-cycles of structures that * reference @FT_Face objects. * * @input: * face :: * A handle to a target face object. * * @return: * FreeType error code. 0~means success. * * @since: * 2.4.2 * */ FT_EXPORT( FT_Error ) FT_Reference_Face( FT_Face face ); /************************************************************************** * * @function: * FT_Done_Face * * @description: * Discard a given face object, as well as all of its child slots and * sizes. * * @input: * face :: * A handle to a target face object. * * @return: * FreeType error code. 0~means success. * * @note: * See the discussion of reference counters in the description of * @FT_Reference_Face. */ FT_EXPORT( FT_Error ) FT_Done_Face( FT_Face face ); /************************************************************************** * * @section: * sizing_and_scaling * */ /************************************************************************** * * @function: * FT_Select_Size * * @description: * Select a bitmap strike. To be more precise, this function sets the * scaling factors of the active @FT_Size object in a face so that * bitmaps from this particular strike are taken by @FT_Load_Glyph and * friends. * * @inout: * face :: * A handle to a target face object. * * @input: * strike_index :: * The index of the bitmap strike in the `available_sizes` field of * @FT_FaceRec structure. * * @return: * FreeType error code. 0~means success. * * @note: * For bitmaps embedded in outline fonts it is common that only a subset * of the available glyphs at a given ppem value is available. FreeType * silently uses outlines if there is no bitmap for a given glyph index. * * For GX and OpenType variation fonts, a bitmap strike makes sense only * if the default instance is active (that is, no glyph variation takes * place); otherwise, FreeType simply ignores bitmap strikes. The same * is true for all named instances that are different from the default * instance. * * Don't use this function if you are using the FreeType cache API. */ FT_EXPORT( FT_Error ) FT_Select_Size( FT_Face face, FT_Int strike_index ); /************************************************************************** * * @enum: * FT_Size_Request_Type * * @description: * An enumeration type that lists the supported size request types, i.e., * what input size (in font units) maps to the requested output size (in * pixels, as computed from the arguments of @FT_Size_Request). * * @values: * FT_SIZE_REQUEST_TYPE_NOMINAL :: * The nominal size. The `units_per_EM` field of @FT_FaceRec is used * to determine both scaling values. * * This is the standard scaling found in most applications. In * particular, use this size request type for TrueType fonts if they * provide optical scaling or something similar. Note, however, that * `units_per_EM` is a rather abstract value which bears no relation to * the actual size of the glyphs in a font. * * FT_SIZE_REQUEST_TYPE_REAL_DIM :: * The real dimension. The sum of the `ascender` and (minus of) the * `descender` fields of @FT_FaceRec is used to determine both scaling * values. * * FT_SIZE_REQUEST_TYPE_BBOX :: * The font bounding box. The width and height of the `bbox` field of * @FT_FaceRec are used to determine the horizontal and vertical * scaling value, respectively. * * FT_SIZE_REQUEST_TYPE_CELL :: * The `max_advance_width` field of @FT_FaceRec is used to determine * the horizontal scaling value; the vertical scaling value is * determined the same way as @FT_SIZE_REQUEST_TYPE_REAL_DIM does. * Finally, both scaling values are set to the smaller one. This type * is useful if you want to specify the font size for, say, a window of * a given dimension and 80x24 cells. * * FT_SIZE_REQUEST_TYPE_SCALES :: * Specify the scaling values directly. * * @note: * The above descriptions only apply to scalable formats. For bitmap * formats, the behaviour is up to the driver. * * See the note section of @FT_Size_Metrics if you wonder how size * requesting relates to scaling values. */ FT_Size_Request_Type; /************************************************************************** * * @struct: * FT_Size_RequestRec * * @description: * A structure to model a size request. * * @fields: * type :: * See @FT_Size_Request_Type. * * width :: * The desired width, given as a 26.6 fractional point value (with 72pt * = 1in). * * height :: * The desired height, given as a 26.6 fractional point value (with * 72pt = 1in). * * horiResolution :: * The horizontal resolution (dpi, i.e., pixels per inch). If set to * zero, `width` is treated as a 26.6 fractional **pixel** value, which * gets internally rounded to an integer. * * vertResolution :: * The vertical resolution (dpi, i.e., pixels per inch). If set to * zero, `height` is treated as a 26.6 fractional **pixel** value, * which gets internally rounded to an integer. * * @note: * If `width` is zero, the horizontal scaling value is set equal to the * vertical scaling value, and vice versa. * * If `type` is `FT_SIZE_REQUEST_TYPE_SCALES`, `width` and `height` are * interpreted directly as 16.16 fractional scaling values, without any * further modification, and both `horiResolution` and `vertResolution` * are ignored. */ FT_Size_RequestRec; /************************************************************************** * * @struct: * FT_Size_Request * * @description: * A handle to a size request structure. */ FT_Size_Request; /************************************************************************** * * @function: * FT_Request_Size * * @description: * Resize the scale of the active @FT_Size object in a face. * * @inout: * face :: * A handle to a target face object. * * @input: * req :: * A pointer to a @FT_Size_RequestRec. * * @return: * FreeType error code. 0~means success. * * @note: * Although drivers may select the bitmap strike matching the request, * you should not rely on this if you intend to select a particular * bitmap strike. Use @FT_Select_Size instead in that case. * * The relation between the requested size and the resulting glyph size * is dependent entirely on how the size is defined in the source face. * The font designer chooses the final size of each glyph relative to * this size. For more information refer to * 'https://www.freetype.org/freetype2/docs/glyphs/glyphs-2.html'. * * Contrary to @FT_Set_Char_Size, this function doesn't have special code * to normalize zero-valued widths, heights, or resolutions, which are * treated as @FT_LOAD_NO_SCALE. * * Don't use this function if you are using the FreeType cache API. */ FT_EXPORT( FT_Error ) FT_Request_Size( FT_Face face, FT_Size_Request req ); /************************************************************************** * * @function: * FT_Set_Char_Size * * @description: * Call @FT_Request_Size to request the nominal size (in points). * * @inout: * face :: * A handle to a target face object. * * @input: * char_width :: * The nominal width, in 26.6 fractional points. * * char_height :: * The nominal height, in 26.6 fractional points. * * horz_resolution :: * The horizontal resolution in dpi. * * vert_resolution :: * The vertical resolution in dpi. * * @return: * FreeType error code. 0~means success. * * @note: * While this function allows fractional points as input values, the * resulting ppem value for the given resolution is always rounded to the * nearest integer. * * If either the character width or height is zero, it is set equal to * the other value. * * If either the horizontal or vertical resolution is zero, it is set * equal to the other value. * * A character width or height smaller than 1pt is set to 1pt; if both * resolution values are zero, they are set to 72dpi. * * Don't use this function if you are using the FreeType cache API. */ FT_EXPORT( FT_Error ) FT_Set_Char_Size( FT_Face face, FT_F26Dot6 char_width, FT_F26Dot6 char_height, FT_UInt horz_resolution, FT_UInt vert_resolution ); /************************************************************************** * * @function: * FT_Set_Pixel_Sizes * * @description: * Call @FT_Request_Size to request the nominal size (in pixels). * * @inout: * face :: * A handle to the target face object. * * @input: * pixel_width :: * The nominal width, in pixels. * * pixel_height :: * The nominal height, in pixels. * * @return: * FreeType error code. 0~means success. * * @note: * You should not rely on the resulting glyphs matching or being * constrained to this pixel size. Refer to @FT_Request_Size to * understand how requested sizes relate to actual sizes. * * Don't use this function if you are using the FreeType cache API. */ FT_EXPORT( FT_Error ) FT_Set_Pixel_Sizes( FT_Face face, FT_UInt pixel_width, FT_UInt pixel_height ); /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @function: * FT_Load_Glyph * * @description: * Load a glyph into the glyph slot of a face object. * * @inout: * face :: * A handle to the target face object where the glyph is loaded. * * @input: * glyph_index :: * The index of the glyph in the font file. For CID-keyed fonts * (either in PS or in CFF format) this argument specifies the CID * value. * * load_flags :: * A flag indicating what to load for this glyph. The @FT_LOAD_XXX * flags can be used to control the glyph loading process (e.g., * whether the outline should be scaled, whether to load bitmaps or * not, whether to hint the outline, etc). * * @return: * FreeType error code. 0~means success. * * @note: * For proper scaling and hinting, the active @FT_Size object owned by * the face has to be meaningfully initialized by calling * @FT_Set_Char_Size before this function, for example. The loaded * glyph may be transformed. See @FT_Set_Transform for the details. * * For subsetted CID-keyed fonts, `FT_Err_Invalid_Argument` is returned * for invalid CID values (that is, for CID values that don't have a * corresponding glyph in the font). See the discussion of the * @FT_FACE_FLAG_CID_KEYED flag for more details. * * If you receive `FT_Err_Glyph_Too_Big`, try getting the glyph outline * at EM size, then scale it manually and fill it as a graphics * operation. */ FT_EXPORT( FT_Error ) FT_Load_Glyph( FT_Face face, FT_UInt glyph_index, FT_Int32 load_flags ); /************************************************************************** * * @section: * character_mapping * */ /************************************************************************** * * @function: * FT_Load_Char * * @description: * Load a glyph into the glyph slot of a face object, accessed by its * character code. * * @inout: * face :: * A handle to a target face object where the glyph is loaded. * * @input: * char_code :: * The glyph's character code, according to the current charmap used in * the face. * * load_flags :: * A flag indicating what to load for this glyph. The @FT_LOAD_XXX * constants can be used to control the glyph loading process (e.g., * whether the outline should be scaled, whether to load bitmaps or * not, whether to hint the outline, etc). * * @return: * FreeType error code. 0~means success. * * @note: * This function simply calls @FT_Get_Char_Index and @FT_Load_Glyph. * * Many fonts contain glyphs that can't be loaded by this function since * its glyph indices are not listed in any of the font's charmaps. * * If no active cmap is set up (i.e., `face->charmap` is zero), the call * to @FT_Get_Char_Index is omitted, and the function behaves identically * to @FT_Load_Glyph. */ FT_EXPORT( FT_Error ) FT_Load_Char( FT_Face face, FT_ULong char_code, FT_Int32 load_flags ); /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @enum: * FT_LOAD_XXX * * @description: * A list of bit field constants for @FT_Load_Glyph to indicate what kind * of operations to perform during glyph loading. * * @values: * FT_LOAD_DEFAULT :: * Corresponding to~0, this value is used as the default glyph load * operation. In this case, the following happens: * * 1. FreeType looks for a bitmap for the glyph corresponding to the * face's current size. If one is found, the function returns. The * bitmap data can be accessed from the glyph slot (see note below). * * 2. If no embedded bitmap is searched for or found, FreeType looks * for a scalable outline. If one is found, it is loaded from the font * file, scaled to device pixels, then 'hinted' to the pixel grid in * order to optimize it. The outline data can be accessed from the * glyph slot (see note below). * * Note that by default the glyph loader doesn't render outlines into * bitmaps. The following flags are used to modify this default * behaviour to more specific and useful cases. * * FT_LOAD_NO_SCALE :: * Don't scale the loaded outline glyph but keep it in font units. * This flag is also assumed if @FT_Size owned by the face was not * properly initialized. * * This flag implies @FT_LOAD_NO_HINTING and @FT_LOAD_NO_BITMAP, and * unsets @FT_LOAD_RENDER. * * If the font is 'tricky' (see @FT_FACE_FLAG_TRICKY for more), using * `FT_LOAD_NO_SCALE` usually yields meaningless outlines because the * subglyphs must be scaled and positioned with hinting instructions. * This can be solved by loading the font without `FT_LOAD_NO_SCALE` * and setting the character size to `font->units_per_EM`. * * FT_LOAD_NO_HINTING :: * Disable hinting. This generally generates 'blurrier' bitmap glyphs * when the glyphs are rendered in any of the anti-aliased modes. See * also the note below. * * This flag is implied by @FT_LOAD_NO_SCALE. * * FT_LOAD_RENDER :: * Call @FT_Render_Glyph after the glyph is loaded. By default, the * glyph is rendered in @FT_RENDER_MODE_NORMAL mode. This can be * overridden by @FT_LOAD_TARGET_XXX or @FT_LOAD_MONOCHROME. * * This flag is unset by @FT_LOAD_NO_SCALE. * * FT_LOAD_NO_BITMAP :: * Ignore bitmap strikes when loading. Bitmap-only fonts ignore this * flag. * * @FT_LOAD_NO_SCALE always sets this flag. * * FT_LOAD_SBITS_ONLY :: * [Since 2.12] This is the opposite of @FT_LOAD_NO_BITMAP, more or * less: @FT_Load_Glyph returns `FT_Err_Invalid_Argument` if the face * contains a bitmap strike for the given size (or the strike selected * by @FT_Select_Size) but there is no glyph in the strike. * * Note that this load flag was part of FreeType since version 2.0.6 * but previously tagged as internal. * * FT_LOAD_VERTICAL_LAYOUT :: * Load the glyph for vertical text layout. In particular, the * `advance` value in the @FT_GlyphSlotRec structure is set to the * `vertAdvance` value of the `metrics` field. * * In case @FT_HAS_VERTICAL doesn't return true, you shouldn't use this * flag currently. Reason is that in this case vertical metrics get * synthesized, and those values are not always consistent across * various font formats. * * FT_LOAD_FORCE_AUTOHINT :: * Prefer the auto-hinter over the font's native hinter. See also the * note below. * * FT_LOAD_PEDANTIC :: * Make the font driver perform pedantic verifications during glyph * loading and hinting. This is mostly used to detect broken glyphs in * fonts. By default, FreeType tries to handle broken fonts also. * * In particular, errors from the TrueType bytecode engine are not * passed to the application if this flag is not set; this might result * in partially hinted or distorted glyphs in case a glyph's bytecode * is buggy. * * FT_LOAD_NO_RECURSE :: * Don't load composite glyphs recursively. Instead, the font driver * fills the `num_subglyph` and `subglyphs` values of the glyph slot; * it also sets `glyph->format` to @FT_GLYPH_FORMAT_COMPOSITE. The * description of subglyphs can then be accessed with * @FT_Get_SubGlyph_Info. * * Don't use this flag for retrieving metrics information since some * font drivers only return rudimentary data. * * This flag implies @FT_LOAD_NO_SCALE and @FT_LOAD_IGNORE_TRANSFORM. * * FT_LOAD_IGNORE_TRANSFORM :: * Ignore the transform matrix set by @FT_Set_Transform. * * FT_LOAD_MONOCHROME :: * This flag is used with @FT_LOAD_RENDER to indicate that you want to * render an outline glyph to a 1-bit monochrome bitmap glyph, with * 8~pixels packed into each byte of the bitmap data. * * Note that this has no effect on the hinting algorithm used. You * should rather use @FT_LOAD_TARGET_MONO so that the * monochrome-optimized hinting algorithm is used. * * FT_LOAD_LINEAR_DESIGN :: * Keep `linearHoriAdvance` and `linearVertAdvance` fields of * @FT_GlyphSlotRec in font units. See @FT_GlyphSlotRec for details. * * FT_LOAD_NO_AUTOHINT :: * Disable the auto-hinter. See also the note below. * * FT_LOAD_COLOR :: * Load colored glyphs. FreeType searches in the following order; * there are slight differences depending on the font format. * * [Since 2.5] Load embedded color bitmap images (provided * @FT_LOAD_NO_BITMAP is not set). The resulting color bitmaps, if * available, have the @FT_PIXEL_MODE_BGRA format, with pre-multiplied * color channels. If the flag is not set and color bitmaps are found, * they are converted to 256-level gray bitmaps, using the * @FT_PIXEL_MODE_GRAY format. * * [Since 2.12] If the glyph index maps to an entry in the face's * 'SVG~' table, load the associated SVG document from this table and * set the `format` field of @FT_GlyphSlotRec to @FT_GLYPH_FORMAT_SVG * ([since 2.13.1] provided @FT_LOAD_NO_SVG is not set). Note that * FreeType itself can't render SVG documents; however, the library * provides hooks to seamlessly integrate an external renderer. See * sections @ot_svg_driver and @svg_fonts for more. * * [Since 2.10, experimental] If the glyph index maps to an entry in * the face's 'COLR' table with a 'CPAL' palette table (as defined in * the OpenType specification), make @FT_Render_Glyph provide a default * blending of the color glyph layers associated with the glyph index, * using the same bitmap format as embedded color bitmap images. This * is mainly for convenience and works only for glyphs in 'COLR' v0 * tables (or glyphs in 'COLR' v1 tables that exclusively use v0 * features). For full control of color layers use * @FT_Get_Color_Glyph_Layer and FreeType's color functions like * @FT_Palette_Select instead of setting @FT_LOAD_COLOR for rendering * so that the client application can handle blending by itself. * * FT_LOAD_NO_SVG :: * [Since 2.13.1] Ignore SVG glyph data when loading. * * FT_LOAD_COMPUTE_METRICS :: * [Since 2.6.1] Compute glyph metrics from the glyph data, without the * use of bundled metrics tables (for example, the 'hdmx' table in * TrueType fonts). This flag is mainly used by font validating or * font editing applications, which need to ignore, verify, or edit * those tables. * * Currently, this flag is only implemented for TrueType fonts. * * FT_LOAD_BITMAP_METRICS_ONLY :: * [Since 2.7.1] Request loading of the metrics and bitmap image * information of a (possibly embedded) bitmap glyph without allocating * or copying the bitmap image data itself. No effect if the target * glyph is not a bitmap image. * * This flag unsets @FT_LOAD_RENDER. * * FT_LOAD_CROP_BITMAP :: * Ignored. Deprecated. * * FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH :: * Ignored. Deprecated. * * @note: * By default, hinting is enabled and the font's native hinter (see * @FT_FACE_FLAG_HINTER) is preferred over the auto-hinter. You can * disable hinting by setting @FT_LOAD_NO_HINTING or change the * precedence by setting @FT_LOAD_FORCE_AUTOHINT. You can also set * @FT_LOAD_NO_AUTOHINT in case you don't want the auto-hinter to be used * at all. * * See the description of @FT_FACE_FLAG_TRICKY for a special exception * (affecting only a handful of Asian fonts). * * Besides deciding which hinter to use, you can also decide which * hinting algorithm to use. See @FT_LOAD_TARGET_XXX for details. * * Note that the auto-hinter needs a valid Unicode cmap (either a native * one or synthesized by FreeType) for producing correct results. If a * font provides an incorrect mapping (for example, assigning the * character code U+005A, LATIN CAPITAL LETTER~Z, to a glyph depicting a * mathematical integral sign), the auto-hinter might produce useless * results. * */ #define FT_LOAD_DEFAULT … #define FT_LOAD_NO_SCALE … #define FT_LOAD_NO_HINTING … #define FT_LOAD_RENDER … #define FT_LOAD_NO_BITMAP … #define FT_LOAD_VERTICAL_LAYOUT … #define FT_LOAD_FORCE_AUTOHINT … #define FT_LOAD_CROP_BITMAP … #define FT_LOAD_PEDANTIC … #define FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH … #define FT_LOAD_NO_RECURSE … #define FT_LOAD_IGNORE_TRANSFORM … #define FT_LOAD_MONOCHROME … #define FT_LOAD_LINEAR_DESIGN … #define FT_LOAD_SBITS_ONLY … #define FT_LOAD_NO_AUTOHINT … /* Bits 16-19 are used by `FT_LOAD_TARGET_` */ #define FT_LOAD_COLOR … #define FT_LOAD_COMPUTE_METRICS … #define FT_LOAD_BITMAP_METRICS_ONLY … #define FT_LOAD_NO_SVG … /* */ /* used internally only by certain font drivers */ #define FT_LOAD_ADVANCE_ONLY … #define FT_LOAD_SVG_ONLY … /************************************************************************** * * @enum: * FT_LOAD_TARGET_XXX * * @description: * A list of values to select a specific hinting algorithm for the * hinter. You should OR one of these values to your `load_flags` when * calling @FT_Load_Glyph. * * Note that a font's native hinters may ignore the hinting algorithm you * have specified (e.g., the TrueType bytecode interpreter). You can set * @FT_LOAD_FORCE_AUTOHINT to ensure that the auto-hinter is used. * * @values: * FT_LOAD_TARGET_NORMAL :: * The default hinting algorithm, optimized for standard gray-level * rendering. For monochrome output, use @FT_LOAD_TARGET_MONO instead. * * FT_LOAD_TARGET_LIGHT :: * A lighter hinting algorithm for gray-level modes. Many generated * glyphs are fuzzier but better resemble their original shape. This * is achieved by snapping glyphs to the pixel grid only vertically * (Y-axis), as is done by FreeType's new CFF engine or Microsoft's * ClearType font renderer. This preserves inter-glyph spacing in * horizontal text. The snapping is done either by the native font * driver, if the driver itself and the font support it, or by the * auto-hinter. * * Advance widths are rounded to integer values; however, using the * `lsb_delta` and `rsb_delta` fields of @FT_GlyphSlotRec, it is * possible to get fractional advance widths for subpixel positioning * (which is recommended to use). * * If configuration option `AF_CONFIG_OPTION_TT_SIZE_METRICS` is * active, TrueType-like metrics are used to make this mode behave * similarly as in unpatched FreeType versions between 2.4.6 and 2.7.1 * (inclusive). * * FT_LOAD_TARGET_MONO :: * Strong hinting algorithm that should only be used for monochrome * output. The result is probably unpleasant if the glyph is rendered * in non-monochrome modes. * * Note that for outline fonts only the TrueType font driver has proper * monochrome hinting support, provided the TTFs contain hints for B/W * rendering (which most fonts no longer provide). If these conditions * are not met it is very likely that you get ugly results at smaller * sizes. * * FT_LOAD_TARGET_LCD :: * A variant of @FT_LOAD_TARGET_LIGHT optimized for horizontally * decimated LCD displays. * * FT_LOAD_TARGET_LCD_V :: * A variant of @FT_LOAD_TARGET_NORMAL optimized for vertically * decimated LCD displays. * * @note: * You should use only _one_ of the `FT_LOAD_TARGET_XXX` values in your * `load_flags`. They can't be ORed. * * If @FT_LOAD_RENDER is also set, the glyph is rendered in the * corresponding mode (i.e., the mode that matches the used algorithm * best). An exception is `FT_LOAD_TARGET_MONO` since it implies * @FT_LOAD_MONOCHROME. * * You can use a hinting algorithm that doesn't correspond to the same * rendering mode. As an example, it is possible to use the 'light' * hinting algorithm and have the results rendered in horizontal LCD * pixel mode, with code like * * ``` * FT_Load_Glyph( face, glyph_index, * load_flags | FT_LOAD_TARGET_LIGHT ); * * FT_Render_Glyph( face->glyph, FT_RENDER_MODE_LCD ); * ``` * * In general, you should stick with one rendering mode. For example, * switching between @FT_LOAD_TARGET_NORMAL and @FT_LOAD_TARGET_MONO * enforces a lot of recomputation for TrueType fonts, which is slow. * Another reason is caching: Selecting a different mode usually causes * changes in both the outlines and the rasterized bitmaps; it is thus * necessary to empty the cache after a mode switch to avoid false hits. * */ #define FT_LOAD_TARGET_( x ) … #define FT_LOAD_TARGET_NORMAL … #define FT_LOAD_TARGET_LIGHT … #define FT_LOAD_TARGET_MONO … #define FT_LOAD_TARGET_LCD … #define FT_LOAD_TARGET_LCD_V … /************************************************************************** * * @macro: * FT_LOAD_TARGET_MODE * * @description: * Return the @FT_Render_Mode corresponding to a given * @FT_LOAD_TARGET_XXX value. * */ #define FT_LOAD_TARGET_MODE( x ) … /************************************************************************** * * @section: * sizing_and_scaling * */ /************************************************************************** * * @function: * FT_Set_Transform * * @description: * Set the transformation that is applied to glyph images when they are * loaded into a glyph slot through @FT_Load_Glyph. * * @inout: * face :: * A handle to the source face object. * * @input: * matrix :: * A pointer to the transformation's 2x2 matrix. Use `NULL` for the * identity matrix. * delta :: * A pointer to the translation vector. Use `NULL` for the null * vector. * * @note: * This function is provided as a convenience, but keep in mind that * @FT_Matrix coefficients are only 16.16 fixed-point values, which can * limit the accuracy of the results. Using floating-point computations * to perform the transform directly in client code instead will always * yield better numbers. * * The transformation is only applied to scalable image formats after the * glyph has been loaded. It means that hinting is unaltered by the * transformation and is performed on the character size given in the * last call to @FT_Set_Char_Size or @FT_Set_Pixel_Sizes. * * Note that this also transforms the `face.glyph.advance` field, but * **not** the values in `face.glyph.metrics`. */ FT_EXPORT( void ) FT_Set_Transform( FT_Face face, FT_Matrix* matrix, FT_Vector* delta ); /************************************************************************** * * @function: * FT_Get_Transform * * @description: * Return the transformation that is applied to glyph images when they * are loaded into a glyph slot through @FT_Load_Glyph. See * @FT_Set_Transform for more details. * * @input: * face :: * A handle to the source face object. * * @output: * matrix :: * A pointer to a transformation's 2x2 matrix. Set this to NULL if you * are not interested in the value. * * delta :: * A pointer to a translation vector. Set this to NULL if you are not * interested in the value. * * @since: * 2.11 * */ FT_EXPORT( void ) FT_Get_Transform( FT_Face face, FT_Matrix* matrix, FT_Vector* delta ); /************************************************************************** * * @section: * glyph_retrieval * */ /************************************************************************** * * @enum: * FT_Render_Mode * * @description: * Render modes supported by FreeType~2. Each mode corresponds to a * specific type of scanline conversion performed on the outline. * * For bitmap fonts and embedded bitmaps the `bitmap->pixel_mode` field * in the @FT_GlyphSlotRec structure gives the format of the returned * bitmap. * * All modes except @FT_RENDER_MODE_MONO use 256 levels of opacity, * indicating pixel coverage. Use linear alpha blending and gamma * correction to correctly render non-monochrome glyph bitmaps onto a * surface; see @FT_Render_Glyph. * * The @FT_RENDER_MODE_SDF is a special render mode that uses up to 256 * distance values, indicating the signed distance from the grid position * to the nearest outline. * * @values: * FT_RENDER_MODE_NORMAL :: * Default render mode; it corresponds to 8-bit anti-aliased bitmaps. * * FT_RENDER_MODE_LIGHT :: * This is equivalent to @FT_RENDER_MODE_NORMAL. It is only defined as * a separate value because render modes are also used indirectly to * define hinting algorithm selectors. See @FT_LOAD_TARGET_XXX for * details. * * FT_RENDER_MODE_MONO :: * This mode corresponds to 1-bit bitmaps (with 2~levels of opacity). * * FT_RENDER_MODE_LCD :: * This mode corresponds to horizontal RGB and BGR subpixel displays * like LCD screens. It produces 8-bit bitmaps that are 3~times the * width of the original glyph outline in pixels, and which use the * @FT_PIXEL_MODE_LCD mode. * * FT_RENDER_MODE_LCD_V :: * This mode corresponds to vertical RGB and BGR subpixel displays * (like PDA screens, rotated LCD displays, etc.). It produces 8-bit * bitmaps that are 3~times the height of the original glyph outline in * pixels and use the @FT_PIXEL_MODE_LCD_V mode. * * FT_RENDER_MODE_SDF :: * This mode corresponds to 8-bit, single-channel signed distance field * (SDF) bitmaps. Each pixel in the SDF grid is the value from the * pixel's position to the nearest glyph's outline. The distances are * calculated from the center of the pixel and are positive if they are * filled by the outline (i.e., inside the outline) and negative * otherwise. Check the note below on how to convert the output values * to usable data. * * @note: * The selected render mode only affects vector glyphs of a font. * Embedded bitmaps often have a different pixel mode like * @FT_PIXEL_MODE_MONO. You can use @FT_Bitmap_Convert to transform them * into 8-bit pixmaps. * * For @FT_RENDER_MODE_SDF the output bitmap buffer contains normalized * distances that are packed into unsigned 8-bit values. To get pixel * values in floating point representation use the following pseudo-C * code for the conversion. * * ``` * // Load glyph and render using FT_RENDER_MODE_SDF, * // then use the output buffer as follows. * * ... * FT_Byte buffer = glyph->bitmap->buffer; * * * for pixel in buffer * { * // `sd` is the signed distance and `spread` is the current spread; * // the default spread is 2 and can be changed. * * float sd = (float)pixel - 128.0f; * * * // Convert to pixel values. * sd = ( sd / 128.0f ) * spread; * * // Store `sd` in a buffer or use as required. * } * * ``` * * FreeType has two rasterizers for generating SDF, namely: * * 1. `sdf` for generating SDF directly from glyph's outline, and * * 2. `bsdf` for generating SDF from rasterized bitmaps. * * Depending on the glyph type (i.e., outline or bitmap), one of the two * rasterizers is chosen at runtime and used for generating SDFs. To * force the use of `bsdf` you should render the glyph with any of the * FreeType's other rendering modes (e.g., `FT_RENDER_MODE_NORMAL`) and * then re-render with `FT_RENDER_MODE_SDF`. * * There are some issues with stability and possible failures of the SDF * renderers (specifically `sdf`). * * 1. The `sdf` rasterizer is sensitive to really small features (e.g., * sharp turns that are less than 1~pixel) and imperfections in the * glyph's outline, causing artifacts in the final output. * * 2. The `sdf` rasterizer has limited support for handling intersecting * contours and *cannot* handle self-intersecting contours whatsoever. * Self-intersection happens when a single connected contour * intersects itself at some point; having these in your font * definitely poses a problem to the rasterizer and cause artifacts, * too. * * 3. Generating SDF for really small glyphs may result in undesirable * output; the pixel grid (which stores distance information) becomes * too coarse. * * 4. Since the output buffer is normalized, precision at smaller spreads * is greater than precision at larger spread values because the * output range of [0..255] gets mapped to a smaller SDF range. A * spread of~2 should be sufficient in most cases. * * Points (1) and (2) can be avoided by using the `bsdf` rasterizer, * which is more stable than the `sdf` rasterizer in general. * */ FT_Render_Mode; /* these constants are deprecated; use the corresponding */ /* `FT_Render_Mode` values instead */ #define ft_render_mode_normal … #define ft_render_mode_mono … /************************************************************************** * * @function: * FT_Render_Glyph * * @description: * Convert a given glyph image to a bitmap. It does so by inspecting the * glyph image format, finding the relevant renderer, and invoking it. * * @inout: * slot :: * A handle to the glyph slot containing the image to convert. * * @input: * render_mode :: * The render mode used to render the glyph image into a bitmap. See * @FT_Render_Mode for a list of possible values. * * If @FT_RENDER_MODE_NORMAL is used, a previous call of @FT_Load_Glyph * with flag @FT_LOAD_COLOR makes `FT_Render_Glyph` provide a default * blending of colored glyph layers associated with the current glyph * slot (provided the font contains such layers) instead of rendering * the glyph slot's outline. This is an experimental feature; see * @FT_LOAD_COLOR for more information. * * @return: * FreeType error code. 0~means success. * * @note: * When FreeType outputs a bitmap of a glyph, it really outputs an alpha * coverage map. If a pixel is completely covered by a filled-in * outline, the bitmap contains 0xFF at that pixel, meaning that * 0xFF/0xFF fraction of that pixel is covered, meaning the pixel is 100% * black (or 0% bright). If a pixel is only 50% covered (value 0x80), * the pixel is made 50% black (50% bright or a middle shade of grey). * 0% covered means 0% black (100% bright or white). * * On high-DPI screens like on smartphones and tablets, the pixels are so * small that their chance of being completely covered and therefore * completely black are fairly good. On the low-DPI screens, however, * the situation is different. The pixels are too large for most of the * details of a glyph and shades of gray are the norm rather than the * exception. * * This is relevant because all our screens have a second problem: they * are not linear. 1~+~1 is not~2. Twice the value does not result in * twice the brightness. When a pixel is only 50% covered, the coverage * map says 50% black, and this translates to a pixel value of 128 when * you use 8~bits per channel (0-255). However, this does not translate * to 50% brightness for that pixel on our sRGB and gamma~2.2 screens. * Due to their non-linearity, they dwell longer in the darks and only a * pixel value of about 186 results in 50% brightness -- 128 ends up too * dark on both bright and dark backgrounds. The net result is that dark * text looks burnt-out, pixely and blotchy on bright background, bright * text too frail on dark backgrounds, and colored text on colored * background (for example, red on green) seems to have dark halos or * 'dirt' around it. The situation is especially ugly for diagonal stems * like in 'w' glyph shapes where the quality of FreeType's anti-aliasing * depends on the correct display of grays. On high-DPI screens where * smaller, fully black pixels reign supreme, this doesn't matter, but on * our low-DPI screens with all the gray shades, it does. 0% and 100% * brightness are the same things in linear and non-linear space, just * all the shades in-between aren't. * * The blending function for placing text over a background is * * ``` * dst = alpha * src + (1 - alpha) * dst , * ``` * * which is known as the OVER operator. * * To correctly composite an anti-aliased pixel of a glyph onto a * surface, * * 1. take the foreground and background colors (e.g., in sRGB space) * and apply gamma to get them in a linear space, * * 2. use OVER to blend the two linear colors using the glyph pixel * as the alpha value (remember, the glyph bitmap is an alpha coverage * bitmap), and * * 3. apply inverse gamma to the blended pixel and write it back to * the image. * * Internal testing at Adobe found that a target inverse gamma of~1.8 for * step~3 gives good results across a wide range of displays with an sRGB * gamma curve or a similar one. * * This process can cost performance. There is an approximation that * does not need to know about the background color; see * https://bel.fi/alankila/lcd/ and * https://bel.fi/alankila/lcd/alpcor.html for details. * * **ATTENTION**: Linear blending is even more important when dealing * with subpixel-rendered glyphs to prevent color-fringing! A * subpixel-rendered glyph must first be filtered with a filter that * gives equal weight to the three color primaries and does not exceed a * sum of 0x100, see section @lcd_rendering. Then the only difference to * gray linear blending is that subpixel-rendered linear blending is done * 3~times per pixel: red foreground subpixel to red background subpixel * and so on for green and blue. */ FT_EXPORT( FT_Error ) FT_Render_Glyph( FT_GlyphSlot slot, FT_Render_Mode render_mode ); /************************************************************************** * * @enum: * FT_Kerning_Mode * * @description: * An enumeration to specify the format of kerning values returned by * @FT_Get_Kerning. * * @values: * FT_KERNING_DEFAULT :: * Return grid-fitted kerning distances in 26.6 fractional pixels. * * FT_KERNING_UNFITTED :: * Return un-grid-fitted kerning distances in 26.6 fractional pixels. * * FT_KERNING_UNSCALED :: * Return the kerning vector in original font units. * * @note: * `FT_KERNING_DEFAULT` returns full pixel values; it also makes FreeType * heuristically scale down kerning distances at small ppem values so * that they don't become too big. * * Both `FT_KERNING_DEFAULT` and `FT_KERNING_UNFITTED` use the current * horizontal scaling factor (as set e.g. with @FT_Set_Char_Size) to * convert font units to pixels. */ FT_Kerning_Mode; /* these constants are deprecated; use the corresponding */ /* `FT_Kerning_Mode` values instead */ #define ft_kerning_default … #define ft_kerning_unfitted … #define ft_kerning_unscaled … /************************************************************************** * * @function: * FT_Get_Kerning * * @description: * Return the kerning vector between two glyphs of the same face. * * @input: * face :: * A handle to a source face object. * * left_glyph :: * The index of the left glyph in the kern pair. * * right_glyph :: * The index of the right glyph in the kern pair. * * kern_mode :: * See @FT_Kerning_Mode for more information. Determines the scale and * dimension of the returned kerning vector. * * @output: * akerning :: * The kerning vector. This is either in font units, fractional pixels * (26.6 format), or pixels for scalable formats, and in pixels for * fixed-sizes formats. * * @return: * FreeType error code. 0~means success. * * @note: * Only horizontal layouts (left-to-right & right-to-left) are supported * by this method. Other layouts, or more sophisticated kernings, are * out of the scope of this API function -- they can be implemented * through format-specific interfaces. * * Kerning for OpenType fonts implemented in a 'GPOS' table is not * supported; use @FT_HAS_KERNING to find out whether a font has data * that can be extracted with `FT_Get_Kerning`. */ FT_EXPORT( FT_Error ) FT_Get_Kerning( FT_Face face, FT_UInt left_glyph, FT_UInt right_glyph, FT_UInt kern_mode, FT_Vector *akerning ); /************************************************************************** * * @function: * FT_Get_Track_Kerning * * @description: * Return the track kerning for a given face object at a given size. * * @input: * face :: * A handle to a source face object. * * point_size :: * The point size in 16.16 fractional points. * * degree :: * The degree of tightness. Increasingly negative values represent * tighter track kerning, while increasingly positive values represent * looser track kerning. Value zero means no track kerning. * * @output: * akerning :: * The kerning in 16.16 fractional points, to be uniformly applied * between all glyphs. * * @return: * FreeType error code. 0~means success. * * @note: * Currently, only the Type~1 font driver supports track kerning, using * data from AFM files (if attached with @FT_Attach_File or * @FT_Attach_Stream). * * Only very few AFM files come with track kerning data; please refer to * Adobe's AFM specification for more details. */ FT_EXPORT( FT_Error ) FT_Get_Track_Kerning( FT_Face face, FT_Fixed point_size, FT_Int degree, FT_Fixed* akerning ); /************************************************************************** * * @section: * character_mapping * */ /************************************************************************** * * @function: * FT_Select_Charmap * * @description: * Select a given charmap by its encoding tag (as listed in * `freetype.h`). * * @inout: * face :: * A handle to the source face object. * * @input: * encoding :: * A handle to the selected encoding. * * @return: * FreeType error code. 0~means success. * * @note: * This function returns an error if no charmap in the face corresponds * to the encoding queried here. * * Because many fonts contain more than a single cmap for Unicode * encoding, this function has some special code to select the one that * covers Unicode best ('best' in the sense that a UCS-4 cmap is * preferred to a UCS-2 cmap). It is thus preferable to @FT_Set_Charmap * in this case. */ FT_EXPORT( FT_Error ) FT_Select_Charmap( FT_Face face, FT_Encoding encoding ); /************************************************************************** * * @function: * FT_Set_Charmap * * @description: * Select a given charmap for character code to glyph index mapping. * * @inout: * face :: * A handle to the source face object. * * @input: * charmap :: * A handle to the selected charmap. * * @return: * FreeType error code. 0~means success. * * @note: * This function returns an error if the charmap is not part of the face * (i.e., if it is not listed in the `face->charmaps` table). * * It also fails if an OpenType type~14 charmap is selected (which * doesn't map character codes to glyph indices at all). */ FT_EXPORT( FT_Error ) FT_Set_Charmap( FT_Face face, FT_CharMap charmap ); /************************************************************************** * * @function: * FT_Get_Charmap_Index * * @description: * Retrieve index of a given charmap. * * @input: * charmap :: * A handle to a charmap. * * @return: * The index into the array of character maps within the face to which * `charmap` belongs. If an error occurs, -1 is returned. * */ FT_EXPORT( FT_Int ) FT_Get_Charmap_Index( FT_CharMap charmap ); /************************************************************************** * * @function: * FT_Get_Char_Index * * @description: * Return the glyph index of a given character code. This function uses * the currently selected charmap to do the mapping. * * @input: * face :: * A handle to the source face object. * * charcode :: * The character code. * * @return: * The glyph index. 0~means 'undefined character code'. * * @note: * If you use FreeType to manipulate the contents of font files directly, * be aware that the glyph index returned by this function doesn't always * correspond to the internal indices used within the file. This is done * to ensure that value~0 always corresponds to the 'missing glyph'. If * the first glyph is not named '.notdef', then for Type~1 and Type~42 * fonts, '.notdef' will be moved into the glyph ID~0 position, and * whatever was there will be moved to the position '.notdef' had. For * Type~1 fonts, if there is no '.notdef' glyph at all, then one will be * created at index~0 and whatever was there will be moved to the last * index -- Type~42 fonts are considered invalid under this condition. */ FT_EXPORT( FT_UInt ) FT_Get_Char_Index( FT_Face face, FT_ULong charcode ); /************************************************************************** * * @function: * FT_Get_First_Char * * @description: * Return the first character code in the current charmap of a given * face, together with its corresponding glyph index. * * @input: * face :: * A handle to the source face object. * * @output: * agindex :: * Glyph index of first character code. 0~if charmap is empty. * * @return: * The charmap's first character code. * * @note: * You should use this function together with @FT_Get_Next_Char to parse * all character codes available in a given charmap. The code should * look like this: * * ``` * FT_ULong charcode; * FT_UInt gindex; * * * charcode = FT_Get_First_Char( face, &gindex ); * while ( gindex != 0 ) * { * ... do something with (charcode,gindex) pair ... * * charcode = FT_Get_Next_Char( face, charcode, &gindex ); * } * ``` * * Be aware that character codes can have values up to 0xFFFFFFFF; this * might happen for non-Unicode or malformed cmaps. However, even with * regular Unicode encoding, so-called 'last resort fonts' (using SFNT * cmap format 13, see function @FT_Get_CMap_Format) normally have * entries for all Unicode characters up to 0x1FFFFF, which can cause *a * lot* of iterations. * * Note that `*agindex` is set to~0 if the charmap is empty. The result * itself can be~0 in two cases: if the charmap is empty or if the * value~0 is the first valid character code. */ FT_EXPORT( FT_ULong ) FT_Get_First_Char( FT_Face face, FT_UInt *agindex ); /************************************************************************** * * @function: * FT_Get_Next_Char * * @description: * Return the next character code in the current charmap of a given face * following the value `char_code`, as well as the corresponding glyph * index. * * @input: * face :: * A handle to the source face object. * * char_code :: * The starting character code. * * @output: * agindex :: * Glyph index of next character code. 0~if charmap is empty. * * @return: * The charmap's next character code. * * @note: * You should use this function with @FT_Get_First_Char to walk over all * character codes available in a given charmap. See the note for that * function for a simple code example. * * Note that `*agindex` is set to~0 when there are no more codes in the * charmap. */ FT_EXPORT( FT_ULong ) FT_Get_Next_Char( FT_Face face, FT_ULong char_code, FT_UInt *agindex ); /************************************************************************** * * @section: * face_creation * */ /************************************************************************** * * @function: * FT_Face_Properties * * @description: * Set or override certain (library or module-wide) properties on a * face-by-face basis. Useful for finer-grained control and avoiding * locks on shared structures (threads can modify their own faces as they * see fit). * * Contrary to @FT_Property_Set, this function uses @FT_Parameter so that * you can pass multiple properties to the target face in one call. Note * that only a subset of the available properties can be controlled. * * * @FT_PARAM_TAG_STEM_DARKENING (stem darkening, corresponding to the * property `no-stem-darkening` provided by the 'autofit', 'cff', * 'type1', and 't1cid' modules; see @no-stem-darkening). * * * @FT_PARAM_TAG_LCD_FILTER_WEIGHTS (LCD filter weights, corresponding * to function @FT_Library_SetLcdFilterWeights). * * * @FT_PARAM_TAG_RANDOM_SEED (seed value for the CFF, Type~1, and CID * 'random' operator, corresponding to the `random-seed` property * provided by the 'cff', 'type1', and 't1cid' modules; see * @random-seed). * * Pass `NULL` as `data` in @FT_Parameter for a given tag to reset the * option and use the library or module default again. * * @input: * face :: * A handle to the source face object. * * num_properties :: * The number of properties that follow. * * properties :: * A handle to an @FT_Parameter array with `num_properties` elements. * * @return: * FreeType error code. 0~means success. * * @example: * Here is an example that sets three properties. You must define * `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` to make the LCD filter examples * work. * * ``` * FT_Parameter property1; * FT_Bool darken_stems = 1; * * FT_Parameter property2; * FT_LcdFiveTapFilter custom_weight = * { 0x11, 0x44, 0x56, 0x44, 0x11 }; * * FT_Parameter property3; * FT_Int32 random_seed = 314159265; * * FT_Parameter properties[3] = { property1, * property2, * property3 }; * * * property1.tag = FT_PARAM_TAG_STEM_DARKENING; * property1.data = &darken_stems; * * property2.tag = FT_PARAM_TAG_LCD_FILTER_WEIGHTS; * property2.data = custom_weight; * * property3.tag = FT_PARAM_TAG_RANDOM_SEED; * property3.data = &random_seed; * * FT_Face_Properties( face, 3, properties ); * ``` * * The next example resets a single property to its default value. * * ``` * FT_Parameter property; * * * property.tag = FT_PARAM_TAG_LCD_FILTER_WEIGHTS; * property.data = NULL; * * FT_Face_Properties( face, 1, &property ); * ``` * * @since: * 2.8 * */ FT_EXPORT( FT_Error ) FT_Face_Properties( FT_Face face, FT_UInt num_properties, FT_Parameter* properties ); /************************************************************************** * * @section: * information_retrieval * */ /************************************************************************** * * @function: * FT_Get_Name_Index * * @description: * Return the glyph index of a given glyph name. This only works * for those faces where @FT_HAS_GLYPH_NAMES returns true. * * @input: * face :: * A handle to the source face object. * * glyph_name :: * The glyph name. * * @return: * The glyph index. 0~means 'undefined character code'. * * @note: * Acceptable glyph names might come from the [Adobe Glyph * List](https://github.com/adobe-type-tools/agl-aglfn). See * @FT_Get_Glyph_Name for the inverse functionality. * * This function has limited capabilities if the config macro * `FT_CONFIG_OPTION_POSTSCRIPT_NAMES` is not defined in `ftoption.h`: * It then works only for fonts that actually embed glyph names (which * many recent OpenType fonts do not). */ FT_EXPORT( FT_UInt ) FT_Get_Name_Index( FT_Face face, const FT_String* glyph_name ); /************************************************************************** * * @function: * FT_Get_Glyph_Name * * @description: * Retrieve the ASCII name of a given glyph in a face. This only works * for those faces where @FT_HAS_GLYPH_NAMES returns true. * * @input: * face :: * A handle to a source face object. * * glyph_index :: * The glyph index. * * buffer_max :: * The maximum number of bytes available in the buffer. * * @output: * buffer :: * A pointer to a target buffer where the name is copied to. * * @return: * FreeType error code. 0~means success. * * @note: * An error is returned if the face doesn't provide glyph names or if the * glyph index is invalid. In all cases of failure, the first byte of * `buffer` is set to~0 to indicate an empty name. * * The glyph name is truncated to fit within the buffer if it is too * long. The returned string is always zero-terminated. * * Be aware that FreeType reorders glyph indices internally so that glyph * index~0 always corresponds to the 'missing glyph' (called '.notdef'). * * This function has limited capabilities if the config macro * `FT_CONFIG_OPTION_POSTSCRIPT_NAMES` is not defined in `ftoption.h`: * It then works only for fonts that actually embed glyph names (which * many recent OpenType fonts do not). */ FT_EXPORT( FT_Error ) FT_Get_Glyph_Name( FT_Face face, FT_UInt glyph_index, FT_Pointer buffer, FT_UInt buffer_max ); /************************************************************************** * * @function: * FT_Get_Postscript_Name * * @description: * Retrieve the ASCII PostScript name of a given face, if available. * This only works with PostScript, TrueType, and OpenType fonts. * * @input: * face :: * A handle to the source face object. * * @return: * A pointer to the face's PostScript name. `NULL` if unavailable. * * @note: * The returned pointer is owned by the face and is destroyed with it. * * For variation fonts, this string changes if you select a different * instance, and you have to call `FT_Get_PostScript_Name` again to * retrieve it. FreeType follows Adobe TechNote #5902, 'Generating * PostScript Names for Fonts Using OpenType Font Variations'. * * https://download.macromedia.com/pub/developer/opentype/tech-notes/5902.AdobePSNameGeneration.html * * [Since 2.9] Special PostScript names for named instances are only * returned if the named instance is set with @FT_Set_Named_Instance (and * the font has corresponding entries in its 'fvar' table or is the * default named instance). If @FT_IS_VARIATION returns true, the * algorithmically derived PostScript name is provided, not looking up * special entries for named instances. */ FT_EXPORT( const char* ) FT_Get_Postscript_Name( FT_Face face ); /************************************************************************** * * @enum: * FT_SUBGLYPH_FLAG_XXX * * @description: * A list of constants describing subglyphs. Please refer to the 'glyf' * table description in the OpenType specification for the meaning of the * various flags (which get synthesized for non-OpenType subglyphs). * * https://docs.microsoft.com/en-us/typography/opentype/spec/glyf#composite-glyph-description * * @values: * FT_SUBGLYPH_FLAG_ARGS_ARE_WORDS :: * FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES :: * FT_SUBGLYPH_FLAG_ROUND_XY_TO_GRID :: * FT_SUBGLYPH_FLAG_SCALE :: * FT_SUBGLYPH_FLAG_XY_SCALE :: * FT_SUBGLYPH_FLAG_2X2 :: * FT_SUBGLYPH_FLAG_USE_MY_METRICS :: * */ #define FT_SUBGLYPH_FLAG_ARGS_ARE_WORDS … #define FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES … #define FT_SUBGLYPH_FLAG_ROUND_XY_TO_GRID … #define FT_SUBGLYPH_FLAG_SCALE … #define FT_SUBGLYPH_FLAG_XY_SCALE … #define FT_SUBGLYPH_FLAG_2X2 … #define FT_SUBGLYPH_FLAG_USE_MY_METRICS … /************************************************************************** * * @function: * FT_Get_SubGlyph_Info * * @description: * Retrieve a description of a given subglyph. Only use it if * `glyph->format` is @FT_GLYPH_FORMAT_COMPOSITE; an error is returned * otherwise. * * @input: * glyph :: * The source glyph slot. * * sub_index :: * The index of the subglyph. Must be less than * `glyph->num_subglyphs`. * * @output: * p_index :: * The glyph index of the subglyph. * * p_flags :: * The subglyph flags, see @FT_SUBGLYPH_FLAG_XXX. * * p_arg1 :: * The subglyph's first argument (if any). * * p_arg2 :: * The subglyph's second argument (if any). * * p_transform :: * The subglyph transformation (if any). * * @return: * FreeType error code. 0~means success. * * @note: * The values of `*p_arg1`, `*p_arg2`, and `*p_transform` must be * interpreted depending on the flags returned in `*p_flags`. See the * OpenType specification for details. * * https://docs.microsoft.com/en-us/typography/opentype/spec/glyf#composite-glyph-description * */ FT_EXPORT( FT_Error ) FT_Get_SubGlyph_Info( FT_GlyphSlot glyph, FT_UInt sub_index, FT_Int *p_index, FT_UInt *p_flags, FT_Int *p_arg1, FT_Int *p_arg2, FT_Matrix *p_transform ); /************************************************************************** * * @enum: * FT_FSTYPE_XXX * * @description: * A list of bit flags used in the `fsType` field of the OS/2 table in a * TrueType or OpenType font and the `FSType` entry in a PostScript font. * These bit flags are returned by @FT_Get_FSType_Flags; they inform * client applications of embedding and subsetting restrictions * associated with a font. * * See * https://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/FontPolicies.pdf * for more details. * * @values: * FT_FSTYPE_INSTALLABLE_EMBEDDING :: * Fonts with no fsType bit set may be embedded and permanently * installed on the remote system by an application. * * FT_FSTYPE_RESTRICTED_LICENSE_EMBEDDING :: * Fonts that have only this bit set must not be modified, embedded or * exchanged in any manner without first obtaining permission of the * font software copyright owner. * * FT_FSTYPE_PREVIEW_AND_PRINT_EMBEDDING :: * The font may be embedded and temporarily loaded on the remote * system. Documents containing Preview & Print fonts must be opened * 'read-only'; no edits can be applied to the document. * * FT_FSTYPE_EDITABLE_EMBEDDING :: * The font may be embedded but must only be installed temporarily on * other systems. In contrast to Preview & Print fonts, documents * containing editable fonts may be opened for reading, editing is * permitted, and changes may be saved. * * FT_FSTYPE_NO_SUBSETTING :: * The font may not be subsetted prior to embedding. * * FT_FSTYPE_BITMAP_EMBEDDING_ONLY :: * Only bitmaps contained in the font may be embedded; no outline data * may be embedded. If there are no bitmaps available in the font, * then the font is unembeddable. * * @note: * The flags are ORed together, thus more than a single value can be * returned. * * While the `fsType` flags can indicate that a font may be embedded, a * license with the font vendor may be separately required to use the * font in this way. */ #define FT_FSTYPE_INSTALLABLE_EMBEDDING … #define FT_FSTYPE_RESTRICTED_LICENSE_EMBEDDING … #define FT_FSTYPE_PREVIEW_AND_PRINT_EMBEDDING … #define FT_FSTYPE_EDITABLE_EMBEDDING … #define FT_FSTYPE_NO_SUBSETTING … #define FT_FSTYPE_BITMAP_EMBEDDING_ONLY … /************************************************************************** * * @function: * FT_Get_FSType_Flags * * @description: * Return the `fsType` flags for a font. * * @input: * face :: * A handle to the source face object. * * @return: * The `fsType` flags, see @FT_FSTYPE_XXX. * * @note: * Use this function rather than directly reading the `fs_type` field in * the @PS_FontInfoRec structure, which is only guaranteed to return the * correct results for Type~1 fonts. * * @since: * 2.3.8 * */ FT_EXPORT( FT_UShort ) FT_Get_FSType_Flags( FT_Face face ); /************************************************************************** * * @section: * glyph_variants * * @title: * Unicode Variation Sequences * * @abstract: * The FreeType~2 interface to Unicode Variation Sequences (UVS), using * the SFNT cmap format~14. * * @description: * Many characters, especially for CJK scripts, have variant forms. They * are a sort of grey area somewhere between being totally irrelevant and * semantically distinct; for this reason, the Unicode consortium decided * to introduce Variation Sequences (VS), consisting of a Unicode base * character and a variation selector instead of further extending the * already huge number of characters. * * Unicode maintains two different sets, namely 'Standardized Variation * Sequences' and registered 'Ideographic Variation Sequences' (IVS), * collected in the 'Ideographic Variation Database' (IVD). * * https://unicode.org/Public/UCD/latest/ucd/StandardizedVariants.txt * https://unicode.org/reports/tr37/ https://unicode.org/ivd/ * * To date (January 2017), the character with the most ideographic * variations is U+9089, having 32 such IVS. * * Three Mongolian Variation Selectors have the values U+180B-U+180D; 256 * generic Variation Selectors are encoded in the ranges U+FE00-U+FE0F * and U+E0100-U+E01EF. IVS currently use Variation Selectors from the * range U+E0100-U+E01EF only. * * A VS consists of the base character value followed by a single * Variation Selector. For example, to get the first variation of * U+9089, you have to write the character sequence `U+9089 U+E0100`. * * Adobe and MS decided to support both standardized and ideographic VS * with a new cmap subtable (format~14). It is an odd subtable because * it is not a mapping of input code points to glyphs, but contains lists * of all variations supported by the font. * * A variation may be either 'default' or 'non-default' for a given font. * A default variation is the one you will get for that code point if you * look it up in the standard Unicode cmap. A non-default variation is a * different glyph. * */ /************************************************************************** * * @function: * FT_Face_GetCharVariantIndex * * @description: * Return the glyph index of a given character code as modified by the * variation selector. * * @input: * face :: * A handle to the source face object. * * charcode :: * The character code point in Unicode. * * variantSelector :: * The Unicode code point of the variation selector. * * @return: * The glyph index. 0~means either 'undefined character code', or * 'undefined selector code', or 'no variation selector cmap subtable', * or 'current CharMap is not Unicode'. * * @note: * If you use FreeType to manipulate the contents of font files directly, * be aware that the glyph index returned by this function doesn't always * correspond to the internal indices used within the file. This is done * to ensure that value~0 always corresponds to the 'missing glyph'. * * This function is only meaningful if * a) the font has a variation selector cmap sub table, and * b) the current charmap has a Unicode encoding. * * @since: * 2.3.6 * */ FT_EXPORT( FT_UInt ) FT_Face_GetCharVariantIndex( FT_Face face, FT_ULong charcode, FT_ULong variantSelector ); /************************************************************************** * * @function: * FT_Face_GetCharVariantIsDefault * * @description: * Check whether this variation of this Unicode character is the one to * be found in the charmap. * * @input: * face :: * A handle to the source face object. * * charcode :: * The character codepoint in Unicode. * * variantSelector :: * The Unicode codepoint of the variation selector. * * @return: * 1~if found in the standard (Unicode) cmap, 0~if found in the variation * selector cmap, or -1 if it is not a variation. * * @note: * This function is only meaningful if the font has a variation selector * cmap subtable. * * @since: * 2.3.6 * */ FT_EXPORT( FT_Int ) FT_Face_GetCharVariantIsDefault( FT_Face face, FT_ULong charcode, FT_ULong variantSelector ); /************************************************************************** * * @function: * FT_Face_GetVariantSelectors * * @description: * Return a zero-terminated list of Unicode variation selectors found in * the font. * * @input: * face :: * A handle to the source face object. * * @return: * A pointer to an array of selector code points, or `NULL` if there is * no valid variation selector cmap subtable. * * @note: * The last item in the array is~0; the array is owned by the @FT_Face * object but can be overwritten or released on the next call to a * FreeType function. * * @since: * 2.3.6 * */ FT_EXPORT( FT_UInt32* ) FT_Face_GetVariantSelectors( FT_Face face ); /************************************************************************** * * @function: * FT_Face_GetVariantsOfChar * * @description: * Return a zero-terminated list of Unicode variation selectors found for * the specified character code. * * @input: * face :: * A handle to the source face object. * * charcode :: * The character codepoint in Unicode. * * @return: * A pointer to an array of variation selector code points that are * active for the given character, or `NULL` if the corresponding list is * empty. * * @note: * The last item in the array is~0; the array is owned by the @FT_Face * object but can be overwritten or released on the next call to a * FreeType function. * * @since: * 2.3.6 * */ FT_EXPORT( FT_UInt32* ) FT_Face_GetVariantsOfChar( FT_Face face, FT_ULong charcode ); /************************************************************************** * * @function: * FT_Face_GetCharsOfVariant * * @description: * Return a zero-terminated list of Unicode character codes found for the * specified variation selector. * * @input: * face :: * A handle to the source face object. * * variantSelector :: * The variation selector code point in Unicode. * * @return: * A list of all the code points that are specified by this selector * (both default and non-default codes are returned) or `NULL` if there * is no valid cmap or the variation selector is invalid. * * @note: * The last item in the array is~0; the array is owned by the @FT_Face * object but can be overwritten or released on the next call to a * FreeType function. * * @since: * 2.3.6 * */ FT_EXPORT( FT_UInt32* ) FT_Face_GetCharsOfVariant( FT_Face face, FT_ULong variantSelector ); /************************************************************************** * * @section: * computations * * @title: * Computations * * @abstract: * Crunching fixed numbers and vectors. * * @description: * This section contains various functions used to perform computations * on 16.16 fixed-point numbers or 2D vectors. FreeType does not use * floating-point data types. * * **Attention**: Most arithmetic functions take `FT_Long` as arguments. * For historical reasons, FreeType was designed under the assumption * that `FT_Long` is a 32-bit integer; results can thus be undefined if * the arguments don't fit into 32 bits. * * @order: * FT_MulDiv * FT_MulFix * FT_DivFix * FT_RoundFix * FT_CeilFix * FT_FloorFix * FT_Vector_Transform * FT_Matrix_Multiply * FT_Matrix_Invert * */ /************************************************************************** * * @function: * FT_MulDiv * * @description: * Compute `(a*b)/c` with maximum accuracy, using a 64-bit intermediate * integer whenever necessary. * * This function isn't necessarily as fast as some processor-specific * operations, but is at least completely portable. * * @input: * a :: * The first multiplier. * * b :: * The second multiplier. * * c :: * The divisor. * * @return: * The result of `(a*b)/c`. This function never traps when trying to * divide by zero; it simply returns 'MaxInt' or 'MinInt' depending on * the signs of `a` and `b`. */ FT_EXPORT( FT_Long ) FT_MulDiv( FT_Long a, FT_Long b, FT_Long c ); /************************************************************************** * * @function: * FT_MulFix * * @description: * Compute `(a*b)/0x10000` with maximum accuracy. Its main use is to * multiply a given value by a 16.16 fixed-point factor. * * @input: * a :: * The first multiplier. * * b :: * The second multiplier. Use a 16.16 factor here whenever possible * (see note below). * * @return: * The result of `(a*b)/0x10000`. * * @note: * This function has been optimized for the case where the absolute value * of `a` is less than 2048, and `b` is a 16.16 scaling factor. As this * happens mainly when scaling from notional units to fractional pixels * in FreeType, it resulted in noticeable speed improvements between * versions 2.x and 1.x. * * As a conclusion, always try to place a 16.16 factor as the _second_ * argument of this function; this can make a great difference. */ FT_EXPORT( FT_Long ) FT_MulFix( FT_Long a, FT_Long b ); /************************************************************************** * * @function: * FT_DivFix * * @description: * Compute `(a*0x10000)/b` with maximum accuracy. Its main use is to * divide a given value by a 16.16 fixed-point factor. * * @input: * a :: * The numerator. * * b :: * The denominator. Use a 16.16 factor here. * * @return: * The result of `(a*0x10000)/b`. */ FT_EXPORT( FT_Long ) FT_DivFix( FT_Long a, FT_Long b ); /************************************************************************** * * @function: * FT_RoundFix * * @description: * Round a 16.16 fixed number. * * @input: * a :: * The number to be rounded. * * @return: * `a` rounded to the nearest 16.16 fixed integer, halfway cases away * from zero. * * @note: * The function uses wrap-around arithmetic. */ FT_EXPORT( FT_Fixed ) FT_RoundFix( FT_Fixed a ); /************************************************************************** * * @function: * FT_CeilFix * * @description: * Compute the smallest following integer of a 16.16 fixed number. * * @input: * a :: * The number for which the ceiling function is to be computed. * * @return: * `a` rounded towards plus infinity. * * @note: * The function uses wrap-around arithmetic. */ FT_EXPORT( FT_Fixed ) FT_CeilFix( FT_Fixed a ); /************************************************************************** * * @function: * FT_FloorFix * * @description: * Compute the largest previous integer of a 16.16 fixed number. * * @input: * a :: * The number for which the floor function is to be computed. * * @return: * `a` rounded towards minus infinity. */ FT_EXPORT( FT_Fixed ) FT_FloorFix( FT_Fixed a ); /************************************************************************** * * @function: * FT_Vector_Transform * * @description: * Transform a single vector through a 2x2 matrix. * * @inout: * vector :: * The target vector to transform. * * @input: * matrix :: * A pointer to the source 2x2 matrix. * * @note: * The result is undefined if either `vector` or `matrix` is invalid. */ FT_EXPORT( void ) FT_Vector_Transform( FT_Vector* vector, const FT_Matrix* matrix ); /************************************************************************** * * @section: * library_setup * */ /************************************************************************** * * @enum: * FREETYPE_XXX * * @description: * These three macros identify the FreeType source code version. Use * @FT_Library_Version to access them at runtime. * * @values: * FREETYPE_MAJOR :: * The major version number. * FREETYPE_MINOR :: * The minor version number. * FREETYPE_PATCH :: * The patch level. * * @note: * The version number of FreeType if built as a dynamic link library with * the 'libtool' package is _not_ controlled by these three macros. * */ #define FREETYPE_MAJOR … #define FREETYPE_MINOR … #define FREETYPE_PATCH … /************************************************************************** * * @function: * FT_Library_Version * * @description: * Return the version of the FreeType library being used. This is useful * when dynamically linking to the library, since one cannot use the * macros @FREETYPE_MAJOR, @FREETYPE_MINOR, and @FREETYPE_PATCH. * * @input: * library :: * A source library handle. * * @output: * amajor :: * The major version number. * * aminor :: * The minor version number. * * apatch :: * The patch version number. * * @note: * The reason why this function takes a `library` argument is because * certain programs implement library initialization in a custom way that * doesn't use @FT_Init_FreeType. * * In such cases, the library version might not be available before the * library object has been created. */ FT_EXPORT( void ) FT_Library_Version( FT_Library library, FT_Int *amajor, FT_Int *aminor, FT_Int *apatch ); /************************************************************************** * * @section: * other_api_data * */ /************************************************************************** * * @function: * FT_Face_CheckTrueTypePatents * * @description: * Deprecated, does nothing. * * @input: * face :: * A face handle. * * @return: * Always returns false. * * @note: * Since May 2010, TrueType hinting is no longer patented. * * @since: * 2.3.5 * */ FT_EXPORT( FT_Bool ) FT_Face_CheckTrueTypePatents( FT_Face face ); /************************************************************************** * * @function: * FT_Face_SetUnpatentedHinting * * @description: * Deprecated, does nothing. * * @input: * face :: * A face handle. * * value :: * New boolean setting. * * @return: * Always returns false. * * @note: * Since May 2010, TrueType hinting is no longer patented. * * @since: * 2.3.5 * */ FT_EXPORT( FT_Bool ) FT_Face_SetUnpatentedHinting( FT_Face face, FT_Bool value ); /* */ FT_END_HEADER #endif /* FREETYPE_H_ */ /* END */
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