Fontconfig Developers Guide Fontconfig KeithPackard krp NAME fontconfig - Font configuration and customization library SYNOPSIS #include <fontconfig/fontconfig.h> #include <fontconfig/fcfreetype.h> DESCRIPTION Fontconfig is a library designed to provide system-wide font configuration, customization and application access. FUNCTIONAL OVERVIEW Fontconfig contains two essential modules, the configuration module which builds an internal configuration from XML files and the matching module which accepts font patterns and returns the nearest matching font. FONT CONFIGURATION The configuration module consists of the FcConfig datatype, libexpat and FcConfigParse which walks over an XML tree and ammends a configuration with data found within. From an external perspective, configuration of the library consists of generating a valid XML tree and feeding that to FcConfigParse. The only other mechanism provided to applications for changing the running configuration is to add fonts and directories to the list of application-provided font files. The intent is to make font configurations relatively static, and shared by as many applications as possible. It is hoped that this will lead to more stable font selection when passing names from one application to another. XML was chosen as a configuration file format because it provides a format which is easy for external agents to edit while retaining the correct structure and syntax. Font configuration is separate from font matching; applications needing to do their own matching can access the available fonts from the library and perform private matching. The intent is to permit applications to pick and choose appropriate functionality from the library instead of forcing them to choose between this library and a private configuration mechanism. The hope is that this will ensure that configuration of fonts for all applications can be centralized in one place. Centralizing font configuration will simplify and regularize font installation and customization. FONT PROPERTIES While font patterns may contain essentially any properties, there are some well known properties with associated types. Fontconfig uses some of these properties for font matching and font completion. Others are provided as a convenience for the applications rendering mechanism. Property Definitions Property CPP Symbol Type Description familyFC_FAMILYStringFont family namestyleFC_STYLEStringFont style. Overrides weight and slantslantFC_SLANTIntItalic, oblique or romanweightFC_WEIGHTIntLight, medium, demibold, bold or blacksizeFC_SIZEDoublePoint sizeaspectFC_ASPECTDoubleStretches glyphs horizontally before hintingpixelsizeFC_PIXEL_SIZEDoublePixel sizespacingFC_SPACINGIntProportional, monospace or charcellfoundryFC_FOUNDRYStringFont foundry nameantialiasFC_ANTIALIASBoolWhether glyphs can be antialiasedhintingFC_HINTINGBoolWhether the rasterizer should use hintingverticallayoutFC_VERTICAL_LAYOUTBoolUse vertical layoutautohintFC_AUTOHINTBoolUse autohinter instead of normal hinterglobaladvanceFC_GLOBAL_ADVANCEBoolUse font global advance datafileFC_FILEStringThe filename holding the fontindexFC_INDEXIntThe index of the font within the fileftfaceFC_FT_FACEFT_FaceUse the specified FreeType face objectrasterizerFC_RASTERIZERStringWhich rasterizer is in useoutlineFC_OUTLINEBoolWhether the glyphs are outlinesscalableFC_SCALABLEBoolWhether glyphs can be scaledscaleFC_SCALEDoubleScale factor for point->pixel conversionsdpiFC_DPIDoubleTarget dots per inchrgbaFC_RGBAIntunknown, rgb, bgr, vrgb, vbgr, none - subpixel geometryminspaceFC_MINSPACEBoolEliminate leading from line spacingcharsetFC_CHARSETCharSetUnicode chars encoded by the fontlangFC_LANGStringList of RFC-3066-style languages this font supports
DATATYPES Fontconfig uses abstract datatypes to hide internal implementation details for most data structures. A few structures are exposed where appropriate. FcChar8, FcChar16, FcChar32, FcBool These are primitive datatypes; the FcChar* types hold precisely the number of bits stated (if supported by the C implementation). FcBool holds one of two CPP symbols: FcFalse or FcTrue. FcMatrix An FcMatrix holds an affine transformation, usually used to reshape glyphs. A small set of matrix operations are provided to manipulate these. typedef struct _FcMatrix { double xx, xy, yx, yy; } FcMatrix; FcCharSet An FcCharSet is an abstract type that holds the set of encoded unicode chars in a font. Operations to build and compare these sets are provided. FcType Tags the kind of data stored in an FcValue. FcValue An FcValue object holds a single value with one of a number of different types. The 'type' tag indicates which member is valid. typedef struct _FcValue { FcType type; union { const FcChar8 *s; int i; FcBool b; double d; const FcMatrix *m; const FcCharSet *c; } u; } FcValue; FcValue Members Type Union member Datatype FcTypeVoid(none)(none)FcTypeIntegeriintFcTypeDoubleddoubleFcTypeStringschar *FcTypeBoolbbFcTypeMatrixmFcMatrix *FcTypeCharSetcFcCharSet *
FcPattern holds a set of names with associated value lists; each name refers to a property of a font. FcPatterns are used as inputs to the matching code as well as holding information about specific fonts. Each property can hold one or more values; conventionally all of the same type, although the interface doesn't demand that. FcFontSet typedef struct _FcFontSet { int nfont; int sfont; FcPattern **fonts; } FcFontSet; An FcFontSet contains a list of FcPatterns. Internally fontconfig uses this data structure to hold sets of fonts. Externally, fontconfig returns the results of listing fonts in this format. 'nfont' holds the number of patterns in the 'fonts' array; 'sfont' is used to indicate the size of that array. FcStrSet, FcStrList FcStrSet holds a list of strings that can be appended to and enumerated. Its unique characteristic is that the enumeration works even while strings are appended during enumeration. FcStrList is used during enumeration to safely and correctly walk the list of strings even while that list is edited in the middle of enumeration. FcObjectSet typedef struct _FcObjectSet { int nobject; int sobject; const char **objects; } FcObjectSet; holds a set of names and is used to specify which fields from fonts are placed in the the list of returned patterns when listing fonts. FcObjectType typedef struct _FcObjectType { const char *object; FcType type; } FcObjectType; marks the type of a pattern element generated when parsing font names. Applications can add new object types so that font names may contain the new elements. FcConstant typedef struct _FcConstant { const FcChar8 *name; const char *object; int value; } FcConstant; Provides for symbolic constants for new pattern elements. When 'name' is seen in a font name, an 'object' element is created with value 'value'. FcBlanks holds a list of Unicode chars which are expected to be blank; unexpectedly blank chars are assumed to be invalid and are elided from the charset associated with the font. FcFileCache holds the per-user cache information for use while loading the font database. This is built automatically for the current configuration when that is loaded. Applications must always pass '0' when one is requested. FcConfig holds a complete configuration of the library; there is one default configuration, other can be constructed from XML data structures. All public entry points that need global data can take an optional FcConfig* argument; passing 0 uses the default configuration. FcConfig objects hold two sets of fonts, the first contains those specified by the configuration, the second set holds those added by the application at run-time. Interfaces that need to reference a particulat set use one of the FcSetName enumerated values. FcSetName Specifies one of the two sets of fonts available in a configuration; FcSetSystem for those fonts specified in the configuration and FcSetApplication which holds fonts provided by the application. FcResult Used as a return type for functions manipulating FcPattern objects. FcResult Values Result Code Meaning FcResultMatchObject exists with the specified IDFcResultNoMatchObject doesn't exist at allFcResultTypeMismatchObject exists, but the type doesn't matchFcResultNoIdObject exists, but has fewer values than specified
FcAtomic Used for locking access to config files. Provides a safe way to update configuration files.
FUNCTIONS Functions are grouped by the main datatype involved FcMatrix FcMatrix structures hold an affine transformation in matrix form. FcMatrixInit #define FcMatrixInit(m) ((m)->xx = (m)->yy = 1, (m)->xy = (m)->yx = 0) Initializes a matrix to the identify transformation. FcMatrixCopy FcMatrix *FcMatrixCopy (const FcMatrix *mat) Allocates a new FcMatrix and copies 'mat' into it. FcMatrixEqual FcBool FcMatrixEqual (const FcMatrix *mat1, const FcMatrix *mat2) Returns FcTrue if 'mat1' and 'mat2' are equal, else FcFalse. FcMatrixMultiply void FcMatrixMultiply (FcMatrix *result, const FcMatrix *a, const FcMatrix *b) Multiplies 'a' and 'b' together, placing the result in 'result'. 'result' may refer to the sam matrix as either 'a' or 'b'. FcMatrixRotate void FcMatrixRotate (FcMatrix *m, double c, double s) If 'c' is cos(angle) and 's' is sin(angle), FcMatrixRotate rotates the matrix by 'angle'. FcMatrixScale void FcMatrixScale (FcMatrix *m, double sx, double sy) Scales 'm' by 'sx' in the horizontal dimension and 'sy' in the vertical dimension. FcMatrixShear void FcMatrixShear (FcMatrix *m, double sh, double sv) Shears 'm' by 'sh' in the horizontal direction and 'sv' in the vertical direction. FcCharSet An FcCharSet is a boolean array indicating a set of unicode chars. Those associated with a font are marked constant and cannot be edited. FcCharSets may be reference counted internally to reduce memory consumption; this may be visible to applications as the result of FcCharSetCopy may return it's argument, and that CharSet may remain unmodifiable. FcCharSetCreate FcCharSet *FcCharSetCreate (void) Creates an empty FcCharSet object. FcCharSetDestroy void FcCharSetDestroy (FcCharSet *fcs) Frees an FcCharSet object. FcCharSetAddChar FcBool FcCharSetAddChar (FcCharSet *fcs, FcChar32 ucs4) Adds a single unicode char to the set, returning FcFalse on failure, either as a result of a constant set or from running out of memory. FcCharSetCopy FcCharSet *FcCharSetCopy (FcCharSet *src) Makes a copy of 'src'; note that this may not actually do anything more than increment the reference count on 'src'. FcCharSetEqual FcBool FcCharSetEqual (const FcCharSet *a, const FcCharSet *b) Returns whether 'a' and 'b' contain the same set of unicode chars. FcCharSetIntersect FcCharSet *FcCharSetIntersect (const FcCharSet *a, const FcCharSet *b) Returns a set including only those chars found in both 'a' and 'b'. FcCharSetUnion FcCharSet *FcCharSetUnion (const FcCharSet *a, const FcCharSet *b); Returns a set including only those chars found in either 'a' or 'b'. FcCharSetSubtract FcCharSet *FcCharSetSubtract (const FcCharSet *a, const FcCharSet *b) Returns a set including only those chars found in 'a' but not 'b'. FcCharSetHasChar FcBool FcCharSetHasChar (const FcCharSet *fcs, FcChar32 ucs4) Returns whether 'fcs' contains the char 'ucs4'. FcCharSetCount FcChar32 FcCharSetCount (const FcCharSet *a) Returns the total number of unicode chars in 'a'. FcCharSetIntersectCount FcChar32 FcCharSetIntersectCount (const FcCharSet *a, const FcCharSet *b) Returns the number of chars that are in both 'a' and 'b'. FcCharSetSubtractCount FcChar32 FcCharSetSubtractCount (const FcCharSet *a, const FcCharSet *b) Returns the number of chars that are in 'a' but not in 'b'. FcCharSetIsSubset FcBool FcCharSetIsSubset (const FcCharSet *a, const FcCharSet *b) Returns whether 'a' is a subset of 'b'. FcCharSetFirstPage FcChar32 FcCharSetFirstPage (const FcCharSet *a, FcChar32 [FC_CHARSET_MAP_SIZE], FcChar32 *next) Builds an array of bits marking the first page of Unicode coverage of 'a'. Returns the base of the array. 'next' contains the next page in the font. FcCharSetNextPage FcChar32 FcCharSetNextPage (const FcCharSet *a, FcChar32 [FC_CHARSET_MAP_SIZE], FcChar32 *next) Builds an array of bits marking the Unicode coverage of 'a' for page '*next'. Returns the base of the array. 'next' contains the next page in the font. FcValue FcValue is a structure containing a type tag and a union of all possible datatypes. The tag is an enum of type FcType and is intended to provide a measure of run-time typechecking, although that depends on careful programming. FcValueDestroy void FcValueDestroy (FcValue v) Frees any memory referenced by `v'. Values of type FcTypeString, FcTypeMatrix and FcTypeCharSet reference memory, the other types do not. FcValueSave FcValue FcValueSave (FcValue v) Returns a copy of `v' duplicating any object referenced by it so that `v' may be safely destroyed without harming the new value. FcPattern An FcPattern is an opaque type that holds both patterns to match against the available fonts, as well as the information about each font. FcPatternCreate FcPattern *FcPatternCreate (void) Creates a pattern with no properties; used to build patterns from scratch. FcPatternDestroy void FcPatternDestroy (FcPattern *p) Destroys a pattern, in the process destroying all related values. FcPatternEqual FcBool FcPatternEqual (const FcPattern *pa, const FcPattern *pb); Returns whether 'pa' and 'pb' are exactly alike. FcPatternEqualSubset FcBool FcPatternEqualSubset (const FcPattern *pa, const FcPattern *pb, const FcObjectSet *os) Returns whether 'pa' and 'pb' have exactly the same values for all of the objects in 'os'. FcPatternHash FcChar32 FcPatternHash (const FcPattern *p) Returns a 32-bit number which is the same for any two patterns which are exactly alike. FcPatternAdd FcBool FcPatternAdd (FcPattern *p, const char *object, FcValue value, FcBool append) Adds a single value to the list of values associated with the property named `object'. If `append' is FcTrue, the value is added at the end of any existing list, otherwise it is inserted at the begining. `value' is saved (with FcValueSave) when inserted into the pattern so that the library retains no reference to any application-supplied data structure. FcPatternAddWeak FcBool FcPatternAddWeak (FcPattern *p, const char *object, FcValue value, FcBool append) FcPatternAddWeak is essentially the same as FcPatternAdd except that any values added to the list have binding 'weak' instead of 'strong'. FcPatternAdd <emphasis>Type</emphasis> FcBool FcPatternAddInteger (FcPattern *p, const char *object, int i) FcBool FcPatternAddDouble (FcPattern *p, const char *object, double d) FcBool FcPatternAddString (FcPattern *p, const char *object, const char *s) FcBool FcPatternAddMatrix (FcPattern *p, const char *object, const FcMatrix *s) FcBool FcPatternAddCharSet (FcPattern *p, const char *object, const FcCharSet *c) FcBool FcPatternAddBool (FcPattern *p, const char *object, FcBool b) These are all convenience functions that insert objects of the specified type into the pattern. Use these in preference to FcPatternAdd as they will provide compile-time typechecking. These all append values to any existing list of values. FcPatternGet FcResult FcPatternGet (FcPattern *p, const char *object, int id, FcValue *v) Returns in `v' the `id'th value associated with the property `object'. The value returned is not a copy, but rather refers to the data stored within the pattern directly. Applications must not free this value. FcPatternGet <emphasis>Type</emphasis> FcResult FcPatternGetInteger (FcPattern *p, const char *object, int n, int *i); FcResult FcPatternGetDouble (FcPattern *p, const char *object, int n, double *d); FcResult FcPatternGetString (FcPattern *p, const char *object, int n, char **const s); FcResult FcPatternGetMatrix (FcPattern *p, const char *object, int n, FcMatrix **s); FcResult FcPatternGetCharSet (FcPattern *p, const char *object, int n, FcCharSet **c); FcResult FcPatternGetBool (FcPattern *p, const char *object, int n, FcBool *b); These are convenience functions that call FcPatternGet and verify that the returned data is of the expected type. They return FcResultTypeMismatch if this is not the case. Note that these (like FcPatternGet) do not make a copy of any data structure referenced by the return value. Use these in preference to FcPatternGet to provide compile-time typechecking. FcPatternBuild, FcPatternVaBuild FcPattern *FcPatternBuild (FcPattern *orig, ...); FcPattern *FcPatternVaBuild (FcPattern *orig, va_list va) Builds a pattern using a list of objects, types and values. Each value to be entered in the pattern is specified with three arguments: Object name, a string describing the property to be added. Object type, one of the FcType enumerated values Value, not an FcValue, but the raw type as passed to any of the FcPatternAdd<type> functions. Must match the type of the second argument. The argument list is terminated by a null object name, no object type nor value need be passed for this. The values are added to `pattern', if `pattern' is null, a new pattern is created. In either case, the pattern is returned. Example pattern = FcPatternBuild (0, FC_FAMILY, FtTypeString, "Times", (char *) 0); FcPatternVaBuild is used when the arguments are already in the form of a varargs value. FcPatternDel FcBool FcPatternDel (FcPattern *p, const char *object) Deletes all values associated with the property `object', returning whether the property existed or not. FcPatternPrint void FcPatternPrint (const FcPattern *p) Prints an easily readable version of the pattern to stdout. There is no provision for reparsing data in this format, it's just for diagnostics and debugging. FcDefaultSubstitute void FcDefaultSubstitute (FcPattern *pattern) Supplies default values for underspecified font patterns: Patterns without a specified style or weight are set to Medium Patterns without a specified style or slant are set to Roman Patterns without a specified pixel size are given one computed from any specified point size (default 12), dpi (default 75) and scale (default 1). FcNameParse FcPattern *FcNameParse (const char *name) Converts 'name' from the standard text format described above into a pattern. FcNameUnparse FcChar8 *FcNameUnparse (FcPattern *pat) Converts the given pattern into the standard text format described above. The return value is not static, but instead refers to newly allocated memory which should be freed by the caller. FcFontSet An FcFontSet simply holds a list of patterns; these are used to return the results of listing available fonts. FcFontSetCreate FcFontSet *FcFontSetCreate (void) Creates an empty font set. FcFontSetDestroy void FcFontSetDestroy (FcFontSet *s); Destroys a font set. Note that this destroys any referenced patterns as well. FcFontSetAdd FcBool FcFontSetAdd (FcFontSet *s, FcPattern *font) Adds a pattern to a font set. Note that the pattern is not copied before being inserted into the set. FcObjectSet An FcObjectSet holds a list of pattern property names; it is used to indiciate which properties are to be returned in the patterns from FcFontList. FcObjectSetCreate FcObjectSet *FcObjectSetCreate (void) Creates an empty set. FcObjectSetAdd FcBool FcObjectSetAdd (FcObjectSet *os, const char *object) Adds a proprety name to the set. FcObjectSetDestroy void FcObjectSetDestroy (FcObjectSet *os) Destroys an object set. FcObjectSetBuild, FcObjectSetVaBuild FcObjectSet *FcObjectSetBuild (const char *first, ...) FcObjectSet *FcObjectSetVaBuild (const char *first, va_list va) These build an object set from a null-terminated list of property names. FcObjectType Provides for applcation-specified font name object types so that new pattern elements can be generated from font names. FcNameRegisterObjectTypes FcBool FcNameRegisterObjectTypes (const FcObjectType *types, int ntype) Register 'ntype' new object types. FcNameUnregisterObjectTypes FcBool FcNameUnregisterObjectTypes (const FcObjectType *types, int ntype) Unregister 'ntype' object types. FcNameGetObjectType const FcObjectType *FcNameGetObjectType (const char *object) Return the object type for the pattern element named 'object'. FcConstant Provides for application-specified symbolic constants for font names. FcNameRegisterConstants FcBool FcNameRegisterConstants (const FcConstant *consts, int nconsts) Register 'nconsts' new symbolic constants. FcNameUnregisterConstants FcBool FcNameUnregisterConstants (const FcConstant *consts, int nconsts) Unregister 'nconsts' symbolic constants. FcNameGetConstant const FcConstant *FcNameGetConstant (FcChar8 *string) Return the FcConstant structure related to symbolic constant 'string'. FcNameConstant FcBool FcNameConstant (FcChar8 *string, int *result); Returns whether a symbolic constant with name 'string' is registered, placing the value of the constant in 'result' if present. FcBlanks An FcBlanks object holds a list of Unicode chars which are expected to be blank when drawn. When scanning new fonts, any glyphs which are empty and not in this list will be assumed to be broken and not placed in the FcCharSet associated with the font. This provides a significantly more accurate CharSet for applications. FcBlanksCreate FcBlanks *FcBlanksCreate (void) Creates an empty FcBlanks object. FcBlanksDestroy void FcBlanksDestroy (FcBlanks *b) Destroys an FcBlanks object, freeing any associated memory. FcBlanksAdd FcBool FcBlanksAdd (FcBlanks *b, FcChar32 ucs4) Adds a single character to an FcBlanks object, returning FcFalse if this process ran out of memory. FcBlanksIsMember FcBool FcBlanksIsMember (FcBlanks *b, FcChar32 ucs4) Returns whether the specified FcBlanks object contains the indicated Unicode value. FcConfig An FcConfig object holds the internal representation of a configuration. There is a default configuration which applications may use by passing 0 to any function using the data within an FcConfig. FcConfigCreate FcConfig *FcConfigCreate (void) Creates an empty configuration. FcConfigDestroy void FcConfigDestroy (FcConfig *config) Destroys a configuration and any data associated with it. Note that calling this function with the return from FcConfigGetCurrent will place the library in an indeterminate state. FcConfigSetCurrent FcBool FcConfigSetCurrent (FcConfig *config) Sets the current default configuration to 'config'. Implicitly calls FcConfigBuildFonts if necessary, returning FcFalse if that call fails. FcConfigGetCurrent FcConfig *FcConfigGetCurrent (void) Returns the current default configuration. FcConfigUptoDate FcBool FcConfigUptoDate (FcConfig *config) Checks all of the files related to 'config' and returns whether the in-memory version is in sync with the disk version. FcConfigBuildFonts FcBool FcConfigBuildFonts (FcConfig *config) Builds the set of available fonts for the given configuration. Note that any changes to the configuration after this call have indeterminate effects. Returns FcFalse if this operation runs out of memory. FcConfigGetConfigDirs FcStrList *FcConfigGetConfigDirs (FcConfig *config) Returns the list of font directories specified in the configuration files for 'config'. Does not include any subdirectories. FcConfigGetFontDirs FcStrList *FcConfigGetFontDirs (FcConfig *config) Returns the list of font directories in 'config'. This includes the configured font directories along with any directories below those in the filesystem. FcConfigGetConfigFiles FcStrList *FcConfigGetConfigFiles (FcConfig *config) Returns the list of known configuration files used to generate 'config'. Note that this will not include any configuration done with FcConfigParse. FcConfigGetCache char *FcConfigGetCache (FcConfig *config) Returns the name of the file used to store per-user font information. FcConfigGetFonts FcFontSet *FcConfigGetFonts (FcConfig *config, FcSetName set) Returns one of the two sets of fonts from the configuration as specified by 'set'. FcConfigGetBlanks FcBlanks *FcConfigGetBlanks (FcConfig *config) Returns the FcBlanks object associated with the given configuration, if no blanks were present in the configuration, this function will return 0. FcConfigGetRescanInverval int FcConfigGetRescanInverval (FcConfig *config) Returns the interval between automatic checks of the configuration (in seconds) specified in 'config'. The configuration is checked during a call to FcFontList when this interval has passed since the last check. FcConfigSetRescanInverval FcBool FcConfigSetRescanInverval (FcConfig *config, int rescanInterval) Sets the rescan interval; returns FcFalse if an error occurred. FcConfigAppFontAddFile FcBool FcConfigAppFontAddFile (FcConfig *config, const char *file) Adds an application-specific font to the configuration. FcConfigAppFontAddDir FcBool FcConfigAppFontAddDir (FcConfig *config, const char *dir) Scans the specified directory for fonts, adding each one found to the application-specific set of fonts. FcConfigAppFontClear void FcConfigAppFontClear (FcConfig *config) Clears the set of application-specific fonts. FcConfigSubstituteWithPat FcBool FcConfigSubstituteWithPat (FcConfig *config, FcPattern *p, FcPattern *p_pat FcMatchKind kind) Performs the sequence of pattern modification operations, if 'kind' is FcMatchPattern, then those tagged as pattern operations are applied, else if 'kind' is FcMatchFont, those tagged as font operations are applied and p_pat is used for <test> elements with target=pattern. FcConfigSubstitute FcBool FcConfigSubstitute (FcConfig *config, FcPattern *p, FcMatchKind kind) Calls FcConfigSubstituteWithPat setting p_pat to NULL. FcFontMatch FcPattern *FcFontMatch (FcConfig *config, FcPattern *p, FcResult *result) Returns the font in 'config' most close matching 'p'. This function should be called only after FcConfigSubstitute and FcDefaultSubstitute have been called for 'p'; otherwise the results will not be correct. FcFontSort FcFontSet *FcFontSort (FcConfig *config, FcPattern *p, FcBool trim, FcCharSet **csp, FcResult *result) Returns the list of fonts sorted by closeness to 'p'. If 'trim' is FcTrue, elements in the list which don't include Unicode coverage not provided by earlier elements in the list are elided. The union of Unicode coverage of all of the fonts is returned in 'csp', if 'csp' is not NULL. This function should be called only after FcConfigSubstitute and FcDefaultSubstitute have been called for 'p'; otherwise the results will not be correct. The returned FcFontSet references FcPattern structures which may be shared by the return value from multiple FcFontSort calls, applications must not modify these patterns. Instead, they should be passed, along with 'p' to FcFontRenderPrepare which combines them into a complete pattern. The FcFontSet returned by FcFontSort is destroyed by caling FcFontSetDestroy. FcFontRenderPrepare FcPattern *FcFontRenderPrepare (FcConfig *config, FcPattern *pat, FcPattern *font) Creates a new pattern consisting of elements of 'font' not appearing in 'pat', elements of 'pat' not appearing in 'font' and the best matching value from 'pat' for elements appearing in both. The result is passed to FcConfigSubstitute with 'kind' FcMatchFont and then returned. FcFontList FcFontSet *FcFontList (FcConfig *config, FcPattern *p, FcObjectSet *os) Selects fonts matching 'p', creates patterns from those fonts containing only the objects in 'os' and returns the set of unique such patterns. FcConfigFilename char *FcConfigFilename (const char *name) Given the specified external entity name, return the associated filename. This provides applications a way to convert various configuration file references into filename form. A null or empty 'name' indicates that the default configuration file should be used; which file this references can be overridden with the FC_CONFIG_FILE environment variable. Next, if the name starts with '~', it refers to a file in the current users home directory. Otherwise if the name doesn't start with '/', it refers to a file in the default configuration directory; the built-in default directory can be overridden with the FC_CONFIG_DIR environment variable. Initialization These functions provide some control over how the library is initialized. FcInitLoadConfig FcConfig *FcInitLoadConfig (void) Loads the default configuration file and returns the resulting configuration. Does not load any font information. FcInitLoadConfigAndFonts FcConfig *FcInitLoadConfigAndFonts (void) Loads the default configuration file and builds information about the available fonts. Returns the resulting configuration. FcInit FcBool FcInit (void) Loads the default configuration file and the fonts referenced therein and sets the default configuration to that result. Returns whether this process succeeded or not. If the default configuration has already been loaded, this routine does nothing and returns FcTrue. FcGetVersion int FcGetVersion (void) Returns the version number of the library. FcInitReinitialize FcBool FcInitReinitialize (void) Forces the default configuration file to be reloaded and resets the default configuration. FcInitBringUptoDate FcBool FcInitBringUptoDate (void) Checks the rescan interval in the default configuration, checking the configuration if the interval has passed and reloading the configuration if when any changes are detected. FcAtomic These functions provide a safe way to update config files, allowing ongoing reading of the old config file while locked for writing and ensuring that a consistent and complete version of the config file is always available. FcAtomicCreate FcAtomic * FcAtomicCreate (const FcChar8 *file) Creates a data structure containing data needed to control access to 'file'. Writing is done to a separate file. Once that file is complete, the original configuration file is atomically replaced so that reading process always see a consistent and complete file without the need to lock for reading. FcAtomicLock FcBool FcAtomicLock (FcAtomic *atomic) Attempts to lock the file referenced by 'atomic'. Returns FcFalse if the file is locked by another process, else returns FcTrue and leaves the file locked. FcAtomicNewFile FcChar8 *FcAtomicNewFile (FcAtomic *atomic) Returns the filename for writing a new version of the file referenced by 'atomic'. FcAtomicOrigFile FcChar8 *FcAtomicOrigFile (FcAtomic *atomic) Returns the file refernced by 'atomic'. FcAtomicReplaceOrig FcBool FcAtomicReplaceOrig (FcAtomic *atomic) Replaces the original file referenced by 'atomic' with the new file. FcAtomicDeleteNew void FcAtomicDeleteNew (FcAtomic *atomic) Deletes the new file. FcAtomicUnlock void FcAtomicUnlock (FcAtomic *atomic) Unlocks the file. FcAtomicDestroy void FcAtomicDestroy (FcAtomic *atomic) Destroys 'atomic'. FreeType specific functions #include <fontconfig/fcfreetype.h> While the fontconfig library doesn't insist that FreeType be used as the rasterization mechanism for fonts, it does provide some convenience functions. FcFreeTypeCharIndex FT_UInt FcFreeTypeCharIndex (FT_Face face, FcChar32 ucs4) Maps a Unicode char to a glyph index. This function uses information from several possible underlying encoding tables to work around broken fonts. As a result, this function isn't designed to be used in performance sensitive areas; results from this function are intended to be cached by higher level functions. FcFreeTypeCharSet FcCharSet *FcFreeTypeCharSet (FT_Face face, FcBlanks *blanks) Scans a FreeType face and returns the set of encoded Unicode chars. This scans several encoding tables to build as complete a list as possible. If 'blanks' is not 0, the glyphs in the font are examined and any blank glyphs not in 'blanks' are not placed in the returned FcCharSet. FcFreeTypeQuery FcPattern *FcFreeTypeQuery (const char *file, int id, FcBlanks *blanks, int *count) Constructs a pattern representing the 'id'th font in 'file'. The number of fonts in 'file' is returned in 'count'. XML specific functions FcConfigParseAndLoad FcBool FcConfigParseAndLoad (FcConfig *config, const FcChar8 *file, FcBool complain) Walks the configuration in 'file' and constructs the internal representation in 'config'. Any include files referenced from within 'file' will be loaded with FcConfigLoad and also parsed. If 'complain' is FcFalse, no warning will be displayed if 'file' does not exist. File and Directory routines FcFileScan FcBool FcFileScan (FcFontSet *set, FcStrSet *dirs, FcFileCache *cache, FcBlanks *blanks, const char *file, FcBool force) Scans a single file and adds all fonts found to 'set'. If 'force' is FcTrue, then the file is scanned even if associated information is found in 'cache'. If 'file' is a directory, it is added to 'dirs'. FcDirScan FcBool FcDirScan (FcFontSet *set, FcStrSet *dirs, FcFileCache *cache, FcBlanks *blanks, const char *dir, FcBool force) Scans an entire directory and adds all fonts found to 'set'. If 'force' is FcTrue, then the directory and all files within it are scanned even if information is present in the per-directory cache file or 'cache'. Any subdirectories found are added to 'dirs'. FcDirSave FcBool FcDirSave (FcFontSet *set, FcStrSet *dirs, const char *dir) Creates the per-directory cache file for 'dir' and populates it with the fonts in 'set' and subdirectories in 'dirs'. FcDirCacheValid FcBool FcDirCacheValid (const FcChar8 *cache_file) Returns FcTrue if 'cache_file' is no older than the directory containing it, else FcFalse. FcStrSet and FcStrList A data structure for enumerating strings, used to list directories while scanning the configuration as directories are added while scanning. FcStrSetCreate FcStrSet *FcStrSetCreate (void) Create an empty set. FcStrSetMember FcBool FcStrSetMember (FcStrSet *set, const FcChar8 *s) Returns whether 's' is a member of 'set'. FcStrSetAdd FcBool FcStrSetAdd (FcStrSet *set, const FcChar8 *s) Adds a copy of 's' to 'set'. FcStrSetAddFilename FcBool FcStrSetAddFilename (FcStrSet *set, const FcChar8 *s) Adds a copy 's' to 'set', The copy is created with FcStrCopyFilename so that leading '~' values are replaced with the value of the HOME environment variable. FcStrSetDel FcBool FcStrSetDel (FcStrSet *set, const FcChar8 *s) Removes 's' from 'set', returning FcTrue if 's' was a member else FcFalse. FcStrSetDestroy void FcStrSetDestroy (FcStrSet *set) Destroys 'set'. FcStrListCreate FcStrList *FcStrListCreate (FcStrSet *set) Creates an enumerator to list the strings in 'set'. FcStrListNext FcChar8 *FcStrListNext (FcStrList *list) Returns the next string in 'set'. FcStrListDone void FcStrListDone (FcStrList *list) Destroys the enumerator 'list'. String utilities FcUtf8ToUcs4 int FcUtf8ToUcs4 (FcChar8 *src, FcChar32 *dst, int len) Converts the next Unicode char from 'src' into 'dst' and returns the number of bytes containing the char. 'src' nust be at least 'len' bytes long. FcUcs4ToUtf8 int FcUcs4ToUtf8 (FcChar32 src, FcChar8 dst[FC_UTF8_MAX_LEN]) Converts the Unicode char from 'src' into 'dst' and returns the number of bytes needed to encode the char. FcUtf8Len FcBool FcUtf8Len (FcChar8 *src, int len, int *nchar, int *wchar) Counts the number of Unicode chars in 'len' bytes of 'src'. Places that count in 'nchar'. 'wchar' contains 1, 2 or 4 depending on the number of bytes needed to hold the largest unicode char counted. The return value indicates whether 'src' is a well-formed UTF8 string. FcUtf16ToUcs4 int FcUtf16ToUcs4 (FcChar8 *src, FcEndian endian, FcChar32 *dst, int len) Converts the next Unicode char from 'src' into 'dst' and returns the number of bytes containing the char. 'src' must be at least 'len' bytes long. Bytes of 'src' are combined into 16-bit units according to 'endian'. FcUtf16Len FcBool FcUtf16Len (FcChar8 *src, FcEndian endian, int len, int *nchar, int *wchar) Counts the number of Unicode chars in 'len' bytes of 'src'. Bytes of 'src' are combined into 16-bit units according to 'endian'. Places that count in 'nchar'. 'wchar' contains 1, 2 or 4 depending on the number of bytes needed to hold the largest unicode char counted. The return value indicates whether 'string' is a well-formed UTF16 string. FcStrCopy FcChar8 *FcStrCopy (const FcChar8 *s) Allocates memory, copies 's' and returns the resulting buffer. Yes, this is 'strdup', but that function isn't available on every platform. FcStrCopyFilename FcChar8 *FcStrCopyFilename (const FcChar8 *s) Just like FcStrCopy except that it converts any leading '~' characters in 's' to the value of the HOME environment variable. FcStrCmpIgnoreCase int FcStrCmpIgnoreCase (const char *s1, const char *s2) Returns the usual <0, 0, >0 result of comparing 's1' and 's2'. This test is case-insensitive in the ASCII range and will operate properly with UTF8 encoded strings, although it does not check for well formed strings. FcStrDirname FcChar8 *FcStrDirname (const FcChar8 *file) Returns the directory containing 'file'. FcStrBasename FcChar8 *FcStrBasename (const FcChar8 *file) Returns the filename of 'file' stripped of any leading directory names.