3. The fontconfig API

#include <fontconfig/fontconfig.h>
#include <fontconfig/fcfreetype.h>

While fontconfig is designed to be extensible, it provides a comprehensive set of standard properties and values for fonts.

The following table gives the list of standard font properties. The property name is represented as a string. In C code a C preprocessor symbol may be used to help with typo detection.

Property        CPP symbol      Type    Description

family          FC_FAMILY       String  Font family name
style           FC_STYLE        String  Font style. Overrides weight and slant
slant           FC_SLANT        Int     Italic, oblique or roman
weight          FC_WEIGHT       Int     Light, medium, demibold, bold or black
size            FC_SIZE         Double  Point size
aspect          FC_ASPECT       Double  Stretch glyphs horizontally, then hint
pixelsize       FC_PIXEL_SIZE   Double  Pixel size
spacing         FC_SPACING      Int     Proportional, monospace or charcell
foundry         FC_FOUNDRY      String  Font foundry name
antialias       FC_ANTIALIAS    Bool    Should glyphs be antialiased?
hinting         FC_HINTING      Bool    Should the rasterizer use hinting?
verticallayout  FC_VERTICAL_LAYOUT Bool Use vertical layout
autohint        FC_AUTOHINT     Bool    Use autohinter instead of normal hinter
globaladvance   FC_GLOBAL_ADVANCE Bool  Use font global advance data
file            FC_FILE         String  The filename holding the font
index           FC_INDEX        Int     The index of the font within the file
ftface          FC_FT_FACE      FT_Face Use the specified FreeType face object
rasterizer      FC_RASTERIZER   String  Which rasterizer is in use
outline         FC_OUTLINE      Bool    Whether the glyphs are outlines
scalable        FC_SCALABLE     Bool    Whether glyphs can be scaled
scale           FC_SCALE        Double  Point->pixel conversion scale factor
dpi             FC_DPI          Double  Target dots per inch
rgba            FC_RGBA         Int     unknown, rgb, bgr, vrgb, vbgr, none
                                        - subpixel geometry
source		FC_SOURCE	String  X11, freetype
minspace        FC_MINSPACE     Bool    Eliminate leading from line spacing
charset         FC_CHARSET      CharSet Unicode chars encoded by the font
lang            FC_LANG         String  List of RFC-3066-style languages
                                        this font supports
fontversion	FC_FONTVERSION  Int     From 'head' table

C code can check the fontconfig version number with the numerical preprocessor constants FC_MAJOR, FC_MINOR, and FC_REVISION, or use the combined constant FC_VERSION, defined as FC_MAJOR*10000 + FC_MINOR*100 + FC_REVISION.

The cache version is given by FC_CACHE_VERSION, and is a string, not an integer. This is normally appended to the end of the cache file name, so multiple versions of fontconfig can peacefully co-exist. The cache file names are defined as FC_DIR_CACHE_FILE and FC_USER_CACHE_FILE.

The Boolean constants are FcFalse (0) and FcTrue (1).

Properties used to control the rasterizer, their preprocessor constants, and their types, include:

charwidth	FC_CHAR_WIDTH	Int
charheight	FC_CHAR_HEIGHT	Int
matrix          FC_MATRIX       FcMatrix

Preprocessor constants are defined for common standard font weights. All are Ints.

FC_WEIGHT_LIGHT	    0
FC_WEIGHT_MEDIUM    100
FC_WEIGHT_DEMIBOLD  180
FC_WEIGHT_BOLD	    200
FC_WEIGHT_BLACK	    210

Preprocessor constants are defined for common standard slants. All are Ints.

FC_SLANT_ROMAN	    0
FC_SLANT_ITALIC	    100
FC_SLANT_OBLIQUE    110

Preprocessor constants are defined for the three spacing types. All are Ints, but should be treated as symbolic constants.

FC_PROPORTIONAL	    0
FC_MONO		    100
FC_CHARCELL	    110

Preprocessor constants are defined for the subpixel orders. All are Ints, but should be treated as symbolic constants.

FC_RGBA_UNKNOWN	    0
FC_RGBA_RGB	    1
FC_RGBA_BGR	    2
FC_RGBA_VRGB	    3
FC_RGBA_VBGR	    4
FC_RGBA_NONE	    5

3.1 Data Types

`FcChar8'

`FcChar16'

`FcChar32'

`FcBool'

These are primitive data types; 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; void *f; const FcPattern *p; const FcLangSet *l; } u; } FcValue;

type Union member Datatype FcTypeVoid (none) (none) FcTypeInteger i int FcTypeDouble d double FcTypeString s TcChar8 * FcTypeBool b b FcTypeMatrix m FcMatrix * FcTypeCharSet c FcCharSet * FcTypeFTFace f void * p FcPattern * FcTypeLangSet l FcLangSet *

`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.

Result code Meaning FcResultMatch Object exists with the specified ID FcResultNoMatch Object doesn't exist at all FcResultTypeMismatch Object exists, but the type doesn't match FcResultNoId Object exists, but has fewer values than specified

`FcAtomic'

Used for locking access to config files. Provides a safe way to update configuration files.

`FcMatchKind'

An enumeration containing FcMatchPattern and FcMatchFont.

`FcLangResult'

An enumeration containing FcLangEqual, FcLangDifferentCountry, and FcLangDifferentLang. Presumably FcLangDifferentLang implies FcLangDifferentCountry.

`FcSetName'

An enumeration containing FcSetSystem and FcSetApplication.

`FcEndian'

An enumeration containing FcEndianBig and FcEndianLittle.

3.2 Functions

3.2.1 FcMatrix

FcMatrix structures hold an affine transformation in matrix form.

#define FcMatrixInit(m)	((m)->xx = (m)->yy = 1, (m)->xy = (m)->yx = 0)

Function: FcMatrix * FcMatrixCopy (const FcMatrix *mat)

Allocates a new FcMatrix and copies 'mat' into it.

Function: FcBool FcMatrixEqual (const FcMatrix *mat1, const FcMatrix *var{mat2})

Returns FcTrue if 'mat1' and 'mat2' are equal, else FcFalse.

Function: void FcMatrixMultiply (FcMatrix *result, const FcMatrix *a, const FcMatrix *var{b})

Multiplies 'a' and 'b' together, placing the result in 'result'. 'result' may refer to the same matrix as either 'a' or 'b'.

Function: void FcMatrixRotate (FcMatrix *m, double c, double s)

If 'c' is cos(angle) and 's' is sin(angle), FcMatrixRotate rotates the matrix by 'angle'.

Function: void FcMatrixScale (FcMatrix *m, double sx, double sy)

Scales 'm' by 'sx' in the horizontal dimension and 'sy' in the vertical dimension.

Function: void FcMatrixShear (FcMatrix *m, double sh, double sv)

Shears 'm' by 'sh' in the horizontal direction and 'sv' in the vertical direction.

3.2.2 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 its argument, and that CharSet may remain unmodifiable.

When represented as a string, an FcCharSet is not a pure bitmap; octet values are limited such that FcCharSet objects, when printed, are valid ASCII characters.

Function: FcCharSet * FcCharSetCreate (void)

Creates an empty FcCharSet object.

Function: void FcCharSetDestroy (FcCharSet *fcs)

Frees an FcCharSet object.

Function: 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.

Function: 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'.

Function: FcBool FcCharSetEqual (const FcCharSet *a, const FcCharSet *b)

Returns whether 'a' and 'b' contain the same set of unicode chars.

Function: FcCharSet * FcCharSetIntersect (const FcCharSet *a, const FcCharSet *b)

Returns a set including only those chars found in both 'a' and 'b'.

Function: FcCharSet * FcCharSetUnion (const FcCharSet *a, const FcCharSet *b);

Returns a set including only those chars found in either 'a' or 'b'.

Function: FcCharSet * FcCharSetSubtract (const FcCharSet *a, const FcCharSet *b)

Returns a set including only those chars found in 'a' but not 'b'.

Function: FcBool FcCharSetHasChar (const FcCharSet *fcs, FcChar32 ucs4)

Returns whether 'fcs' contains the char 'ucs4'.

Function: FcChar32 FcCharSetCount (const FcCharSet *a)

Returns the total number of unicode chars in 'a'.

Function: FcChar32 FcCharSetIntersectCount (const FcCharSet *a, const FcCharSet *b)

Returns the number of chars that are in both 'a' and 'b'.

Function: FcChar32 FcCharSetSubtractCount (const FcCharSet *a, const FcCharSet *b)

Returns the number of chars that are in 'a' but not in 'b'.

Function: FcBool FcCharSetIsSubset (const FcCharSet *a, const FcCharSet *b)

Returns whether 'a' is a subset of 'b'.

Function: 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.

Function: 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.

3.2.3 FcValue

FcValue is a structure containing a type tag and a union of all possible data types. 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.

Function: void FcValueDestroy (FcValue v)

Frees any memory referenced by `v'. Values of type FcTypeString, FcTypeMatrix and FcTypeCharSet reference memory, the other types do not.

Function: 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.

Function: void FcValuePrint (const FcValue v)

Prints an easily readable version of the value to stdout. There is no provision for reparsing data in this format, it's just for diagnostics and debugging.

3.2.4 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.

Function: FcPattern * FcPatternCreate (void)

Creates a pattern with no properties; used to build patterns from scratch.

Function: void FcPatternDestroy (FcPattern *p)

Destroys a pattern, in the process destroying all related values.

Function: FcBool FcPatternEqual (const FcPattern *pa, const FcPattern *pb);

Returns whether 'pa' and 'pb' are exactly alike.

Function: 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'.

Function: FcChar32 FcPatternHash (const FcPattern *p)

Returns a 32-bit number which is the same for any two patterns which are exactly alike.

Function: 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.

Function: 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'.

Function: FcBool FcPatternAddInteger (FcPattern *p, const char *object, int i)

Function: FcBool FcPatternAddDouble (FcPattern *p, const char *object, double d)

Function: FcBool FcPatternAddString (FcPattern *p, const char *object, const char *s)

Function: FcBool FcPatternAddMatrix (FcPattern *p, const char *object, const FcMatrix *s)

Function: FcBool FcPatternAddCharSet (FcPattern *p, const char *object, const FcCharSet *c)

Function: 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.

Function: 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.

Function: FcResult FcPatternGetInteger (FcPattern *p, const char *object, int id, int *i);

Function: FcResult FcPatternGetDouble (FcPattern *p, const char *object, int id, double *d);

Function: FcResult FcPatternGetString (FcPattern *p, const char *object, int id, char **const s);

Function: FcResult FcPatternGetMatrix (FcPattern *p, const char *object, int id, FcMatrix **s);

Function: FcResult FcPatternGetCharSet (FcPattern *p, const char *object, int id, FcCharSet **c);

Function: FcResult FcPatternGetBool (FcPattern *p, const char *object, int id, 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.

Function: FcPattern * FcPatternBuild (FcPattern *orig, ...);

Function: 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:

1. Object name, a string describing the property to be added.
2. Object type, one of the FcType enumerated values
3. 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.

Function: FcBool FcPatternDel (FcPattern *p, const char *object)

Deletes all values associated with the property `object', returning whether the property existed or not.

Function: 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.

Function: 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).

Function: FcPattern * FcNameParse (const char *name)

Converts 'name' from the standard text format described above into a pattern.

Function: 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.

3.2.5 FcFontSet

An FcFontSet simply holds a list of patterns; these are used to return the results of listing available fonts.

Function: FcFontSet *FcFontSetCreate (void)

Creates an empty font set.

Function: void FcFontSetDestroy (FcFontSet *s);

Destroys a font set. Note that this destroys any referenced patterns as well.

Function: 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.

Function: void FcFontSetPrint (const FcFontSet *s)

Prints an easily readable version of the font set to stdout. There is no provision for reparsing data in this format, it's just for diagnostics and debugging.

3.2.6 FcObjectSet

An FcObjectSet holds a list of pattern property names; it is used to indicate which properties are to be returned in the patterns from FcFontList.

Function: FcObjectSet *FcObjectSetCreate (void)

Creates an empty set.

Function: FcBool FcObjectSetAdd (FcObjectSet *os, const char *object)

Adds a property name to the set.

Function: void FcObjectSetDestroy (FcObjectSet *os)

Destroys an object set.

Function: FcObjectSet *FcObjectSetBuild (const char *first, ...)

Function: FcObjectSet *FcObjectSetVaBuild (const char *first, va_list va)

These build an object set from a null-terminated list of property names.

3.2.7 FcObjectType

Provides for application-specified font name object types so that new pattern elements can be generated from font names.

Function: FcBool FcNameRegisterObjectTypes (const FcObjectType *types, int ntype)

Register 'ntype' new object types.

Function: FcBool FcNameUnregisterObjectTypes (const FcObjectType *types, int ntype)

Unregister 'ntype' object types.

Function: 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.

Function: FcBool FcNameRegisterConstants (const FcConstant *consts, int nconsts)

Register 'nconsts' new symbolic constants.

Function: FcBool FcNameUnregisterConstants (const FcConstant *consts, int nconsts)

Unregister 'nconsts' symbolic constants.

Function: const FcConstant *FcNameGetConstant (FcChar8 *string)

Return the FcConstant structure related to symbolic constant 'string'.

Function: 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.

3.2.8 FcLangSet

An FcLangSet holds a set of RFC 3066 language tags, 2.6 LANG Tags. This module provides functions to determine whether a given language is fully supported by a font. Partial support can be determined using the font's character set, 3.2.2 FcCharSet.

Function: FcLangSet *FcLangSetCreate (void);

Create an empty FcLangSet.

Function: void FcLangSetDestroy (FcLangSet *ls);

Destroy a FcLangSet, freeing any associated storage.

Function: FcLangSet *FcLangSetCopy (const FcLangSet *ls);

Copy ls to a newly allocated FcLangSet.

Function: FcBool FcLangSetAdd (FcLangSet *ls, const FcChar8 *lang);

Add lang to FcLangSet ls.

Function: FcLangResult FcLangSetHasLang (const FcLangSet *ls, const FcChar8 *lang);

Check whether lang is a member of FcLangSet ls. Note that the return value is a FcLangResult, not a Boolean.

Function: FcLangResult FcLangSetCompare (const FcLangSet *lsa, const FcLangSet *lsb);

#### Document me.

Function: FcBool FcLangSetEqual (const FcLangSet *lsa, const FcLangSet *lsb);

Check whether the FcLangSets lsa and lsb contain the same members.

Function: FcChar32 FcLangSetHash (const FcLangSet *ls);

Return a hash value; two FcLangSets which hash to different values cannot contain the same members.

3.2.9 Querying Fonts and Their Properties

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.

Function: FcBlanks *FcBlanksCreate (void)

Creates an empty FcBlanks object.

Function: void FcBlanksDestroy (FcBlanks *b)

Destroys an FcBlanks object, freeing any associated memory.

Function: FcBool FcBlanksAdd (FcBlanks *b, FcChar32 ucs4)

Adds a single character to an FcBlanks object, returning FcFalse if this process ran out of memory.

Function: FcBool FcBlanksIsMember (FcBlanks *b, FcChar32 ucs4)

Returns whether the specified FcBlanks object contains the indicated Unicode value.

The site or user may specify substitutions for certain font patterns, for convenience or to get more accurate results for the local installation or preferences. These functions execute the substitution based on a specified configuration.

Function: 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.

Function: FcBool FcConfigSubstitute (FcConfig *config, FcPattern *p, FcMatchKind kind)

Calls FcConfigSubstituteWithPat setting p_pat to NULL.

The following functions return fonts that match a certain pattern. FcFontRenderPrepare and FcFontMatch always return a single best match. FcFontList returns the list of fonts that match a a given pattern on a certain set of properties. FcFontSort returns the entire list of fonts, sorted in order of match quality, possibly filtering out fonts that do not provide additional characters beyond those provided by preferred fonts.

Function: 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.

Function: 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.

Function: FcFontSet *FcFontList (FcConfig *config, FcPattern *p, FcObjectSet *os)

Selects fonts matching 'p', creates patterns containing only the objects in 'os' from those fonts, and returns the set of unique such patterns.

The FcFontSet returned by FcFontList is destroyed by calling FcFontSetDestroy.

Function: FcFontSet *FcFontSort (FcConfig *config, FcPattern *p, FcBool trim, FcCharSet **csp, FcResult *result)

Returns the list of all 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 calling FcFontSetDestroy.

3.2.10 Initialization

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.

Function: FcConfig *FcConfigCreate (void)

Creates an empty configuration.

Function: void FcConfigDestroy (FcConfig *config)

Destroys a configuration and any data associated with it. Note that calling this function with the return value from FcConfigGetCurrent will place the library in an indeterminate state.

Function: FcBool FcConfigSetCurrent (FcConfig *config)

Sets the current default configuration to 'config'. Implicitly calls FcConfigBuildFonts if necessary, returning FcFalse if that call fails.

Function: FcConfig *FcConfigGetCurrent (void)

Returns the current default configuration.

Function: 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.

Function: 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.

Function: FcStrList *FcConfigGetConfigDirs (FcConfig *config)

Returns the list of font directories specified in the configuration files for 'config'. Does not include any subdirectories.

Function: 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.

Function: 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.

Function: char *FcConfigGetCache (FcConfig *config)

Returns the name of the file used to store per-user font information.

Function: FcFontSet *FcConfigGetFonts (FcConfig *config, FcSetName set)

Returns one of the two sets of fonts from the configuration as specified by 'set'.

Function: 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.

Function: 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.

Function: FcBool FcConfigSetRescanInverval (FcConfig *config, int rescanInterval)

Sets the rescan interval; returns FcFalse if an error occurred.

Function: FcBool FcConfigAppFontAddFile (FcConfig *config, const char *file)

Adds an application-specific font to the configuration.

Function: FcBool FcConfigAppFontAddDir (FcConfig *config, const char *dir)

Scans the specified directory for fonts, adding each one found to the application-specific set of fonts.

Function: void FcConfigAppFontClear (FcConfig *config)

Clears the set of application-specific fonts.

These functions provide some control over how the default configuration of the library is initialized. (This configuration is normally implicitly initialized.)

Function: 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.

Function: FcConfig *FcInitLoadConfig (void)

Loads the default configuration file and returns the resulting configuration. Does not load any font information.

Function: FcConfig *FcInitLoadConfigAndFonts (void)

Loads the default configuration file and builds information about the available fonts. Returns the resulting configuration.

Function: 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.

Function: int FcGetVersion (void)

Returns the version number of the library.

Function: FcBool FcInitReinitialize (void)

Forces the default configuration file to be reloaded and resets the default configuration.

Function: FcBool FcInitBringUptoDate (void)

Checks the rescan interval in the default configuration, checking the configuration if the interval has passed and reloading the configuration when any changes are detected.

3.2.11 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.

Function: 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 processes always see a consistent and complete file without the need to lock for reading.

Function: 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.

Function: FcChar8 *FcAtomicNewFile (FcAtomic *atomic)

Returns the filename for writing a new version of the file referenced by 'atomic'.

Function: FcChar8 *FcAtomicOrigFile (FcAtomic *atomic)

Returns the file refernced by 'atomic'.

Function: FcBool FcAtomicReplaceOrig (FcAtomic *atomic)

Replaces the original file referenced by 'atomic' with the new file.

Function: void FcAtomicDeleteNew (FcAtomic *atomic)

Deletes the new file.

Function: void FcAtomicUnlock (FcAtomic *atomic)

Unlocks the file.

Function: void FcAtomicDestroy (FcAtomic *atomic)

Destroys 'atomic'.

3.2.12 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.

Function: 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.

Function: 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.

Function: 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'.

3.2.13 XML-Specific Functions

Function: 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.

3.2.14 File and Directory Routines

Function: 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'.

Function: 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'.

Function: 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'.

Function: FcBool FcDirCacheValid (const FcChar8 *cache_file)

Returns FcTrue if 'cache_file' is no older than the directory containing it, else FcFalse.

3.2.15 FcStrSet and FcStrList

A data structure for enumerating strings, used to list directories while scanning the configuration as directories are added while scanning.

Function: FcStrSet *FcStrSetCreate (void)

Create an empty set.

Function: FcBool FcStrSetMember (FcStrSet *set, const FcChar8 *s)

Returns whether 's' is a member of 'set'.

Function: FcBool FcStrSetAdd (FcStrSet *set, const FcChar8 *s)

Adds a copy of 's' to 'set'.

Function: FcBool FcStrSetAddFilename (FcStrSet *set, const FcChar8 *s)

Adds a copy of 's' to 'set', The copy is created with FcStrCopyFilename so that leading '~' values are replaced with the value of the HOME environment variable.

Function: FcBool FcStrSetDel (FcStrSet *set, const FcChar8 *s)

Removes 's' from 'set', returning FcTrue if 's' was a member else FcFalse.

Function: void FcStrSetDestroy (FcStrSet *set)

Destroys 'set'.

Function: FcStrList *FcStrListCreate (FcStrSet *set)

Creates an enumerator to list the strings in 'set'.

Function: FcChar8 *FcStrListNext (FcStrList *list)

Returns the next string in 'set'.

Function: void FcStrListDone (FcStrList *list)

Destroys the enumerator 'list'.

3.2.16 String Utilities

Function: 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' must be at least 'len' bytes long.

Function: 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.

Function: 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.

Function: 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'.

Function: 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.

Function: 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.

Function: 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.

Function: 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.

Function: FcChar8 *FcStrDirname (const FcChar8 *file)

Returns the directory containing 'file'.

Function: FcChar8 *FcStrBasename (const FcChar8 *file)

Returns the filename of 'file' stripped of any leading directory names.

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