fontconfig(3) fontconfig(3)
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 configura-
tion, 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 configura-
tion with data found within. From an external perspective, configura-
tion of the library consists of generating a valid XML tree and feeding
that to FcConfigParse. The only other mechanism provided to applica-
tions for changing the running configuration is to add fonts and direc-
tories 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 applica-
tions 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 con-
figuration of fonts for all applications can be centralized in one
place. Centralizing font configuration will make simplify and regular-
ize 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 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 Stretches glyphs horizontally before hinting
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 Whether glyphs can be antialiased
hinting FC_HINTING Bool Whether the rasterizer should use hinting
verticallayout FC_VERTICAL_LAYOUT BoolUse vertical layout
autohint FC_AUTOHINT Bool Use autohinter instead of normal hinter
globaladvance FC_GLOBAL_ADVANCE BoolUse 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 StringWhich 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 Scale factor for point->pixel conversions
dpi FC_DPI Double Target dots per inch
rgba FC_RGBA Int unknown, rgb, bgr, vrgb, vbgr, none - subpixel geometry
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
FONT MATCHING
Fontconfig performs matching by measuring the distance from a provided
pattern to all of the available fonts in the system. The closest
matching font is selected. This ensures that a font will always be
returned, but doesn't ensure that it is anything like the requested
pattern.
Font matching starts with an application constructed pattern. The
desired attributes of the resulting font are collected together in an
FcPattern object. Each property of the pattern can contain one or more
values; these are listed in priority order; matches earlier in the list
are considered "closer" than matches later in the list.
The initial pattern is modified by applying the list of editing
instructions specific to patterns found in the configuration; each con-
sists of a match predicate and a set of editing operations. They are
executed in the order they appeared in the configuration. Each match
causes the associated sequence of editing operations to be applied.
After the pattern has been edited, a sequence of default substitutions
are performed to canonicalize the set of available properties; this
avoids the need for the lower layers to constantly provide default val-
ues for various font properties during rendering.
The canonical font pattern is finally matched against all available
fonts. The distance from the pattern to the font is measured for each
of several properties: foundry, charset, family, lang, spacing, pixel-
size, style, slant, weight, antialias, rasterizer and outline. This
list is in priority order -- results of comparing earlier elements of
this list weigh more heavily than later elements.
There is one special case to this rule; family names are split into two
bindings; strong and weak. Strong family names are given greater
precedence in the match than lang elements while weak family names are
given lower precedence than lang elements. This permits the document
language to drive font selection when any document specified font is
unavailable.
The pattern representing that font is augmented to include any proper-
ties found in the pattern but not found in the font itself; this per-
mits the application to pass rendering instructions or any other data
through the matching system. Finally, the list of editing instructions
specific to fonts found in the configuration are applied to the pat-
tern. This modified pattern is returned to the application.
The return value contains sufficient information to locate and raster-
ize the font, including the file name, pixel size and other rendering
data. As none of the information involved pertains to the FreeType
library, applications are free to use any rasterization engine or even
to take the identified font file and access it directly.
The match/edit sequences in the configuration are performed in two
passes because there are essentially two different operations necessary
-- the first is to modify how fonts are selected; aliasing families and
adding suitable defaults. The second is to modify how the selected
fonts are rasterized. Those must apply to the selected font, not the
original pattern as false matches will often occur.
FONT LIST MATCHING
While many applications want to locate a single font best matching
their search criteria, other applications need to build a set of fonts
which can be used to present any Unicode data. Fontconfig provides an
API to generate a list sorted by the nearness of each font to the pat-
tern. Every font in the system is considered, the best matching fonts
are placed first. The application then can select whether the remain-
ing fonts are unconditionally included in the list, or whether they are
included only if they cover portions of Unicode not covered by any of
the preceeding fonts.
The list resulting from this match is represented by references to the
original font patterns and so consumes very little memory. Using a
list entry involves creating a pattern which combines the information
from the font with the information from the original pattern and exe-
cuting the font substitutions.
FONT NAMES
Fontconfig provides a textual representation for patterns that the
library can both accept and generate. The representation is in three
parts, first a list of family names, second a list of point sizes and
finally a list of additional properties:
<families>-<point sizes>:<name1>=<values1>:<name2>=<values2>...
Values in a list are separated with commas. The name needn't include
either families or point sizes; they can be elided. In addition, there
are symbolic constants that simultaneously indicate both a name and a
value. Here are some examples:
Times-12 12 point Times Roman
Times-12:bold 12 point Times Bold
Courier:italic Courier Italic in the default size
Monospace:matrix=1 .1 0 1The users preferred monospace font
with artificial obliquing
LANG TAGS
Each font in the database contains a list of languages it supports.
This is computed by comparing the Unicode coverage of the font with the
orthography of each language. Languages are tagged using an RFC-3066
compatible naming and occur in two parts -- the ISO639 language tag
followed a hyphen and then by the ISO 3166 country code. The hyphen
and country code may be elided.
Fontconfig has orthographies for several languages built into the
library. No provision has been made for adding new ones aside from
rebuilding the library. It currently supports 122 of the 139 languages
named in ISO 639-1, 141 of the languages with two-letter codes from ISO
639-2 and another 30 languages with only three-letter codes.
DATATYPES
FcChar8
FcChar16
FcChar32
FcBool These are primitive datatypes; the FcChar* types hold precisely
the number of bits stated (if supported by the C implementa-
tion). 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;
type Union member Datatype
------------------------------
FcTypeVoid (none) (none)
FcTypeInteger i int
FcTypeDouble d double
FcTypeString s char *
FcTypeBool b b
FcTypeMatrix m FcMatrix *
FcTypeCharSet c FcCharSet *
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 spe-
cific fonts. Each property can hold one or more values; conven-
tionally 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 fontcon-
fig 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 enu-
meration works even while strings are appended during enumera-
tion. FcStrList is used during enumeration to safely and cor-
rectly 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 list-
ing 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 con-
figuration 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. Inter-
faces 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 configura-
tion; FcSetSystem for those fonts specified in the configuration
and FcSetApplication which holds fonts provided by the applica-
tion.
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.
FUNCTIONS
FcMatrix
FcMatrix structures hold an affine transformation in matrix form.
Initializes a matrix to the identify transformation.
FcMatrix *FcMatrixCopy (const FcMatrix *mat)
Allocates a new FcMatrix and copies 'mat' into it.
FcBool FcMatrixEqual (const FcMatrix *mat1, const FcMatrix *mat2)
Returns FcTrue if 'mat1' and 'mat2' are equal, else FcFalse.
void FcMatrixMultiply (FcMatrix *result, const FcMatrix *a, const FcMa-
trix *b)
Multiplies 'a' and 'b' together, placing the result in 'result'.
'result' may refer to the sam matrix as either 'a' or 'b'.
void FcMatrixRotate (FcMatrix *m, double c, double s)
If 'c' is cos(angle) and 's' is sin(angle), FcMatrixRotate
rotates the matrix by 'angle'.
void FcMatrixScale (FcMatrix *m, double sx, double sy)
Scales 'm' by 'sx' in the horizontal dimension and 'sy' in the
vertical dimension.
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 con-
sumption; this may be visible to applications as the result of FcCha-
rSetCopy may return it's argument, and that CharSet may remain unmodi-
fiable.
FcCharSet *FcCharSetCreate (void)
Creates an empty FcCharSet object.
void FcCharSetDestroy (FcCharSet *fcs)
Frees an FcCharSet object.
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.
FcCharSet *FcCharSetCopy (FcCharSet *src)
Makes a copy of 'src'; note that this may not actually do any-
thing more than increment the reference count on 'src'.
FcBool FcCharSetEqual (const FcCharSet *a, const FcCharSet *b)
Returns whether 'a' and 'b' contain the same set of unicode
chars.
FcCharSet *FcCharSetIntersect (const FcCharSet *a, const FcCharSet *b)
Returns a set including only those chars found in both 'a' and
'b'.
FcCharSet *FcCharSetUnion (const FcCharSet *a, const FcCharSet *b);
Returns a set including only those chars found in either 'a' or
'b'.
FcCharSet *FcCharSetSubtract (const FcCharSet *a, const FcCharSet *b)
Returns a set including only those chars found in 'a' but not
'b'.
FcBool FcCharSetHasChar (const FcCharSet *fcs, FcChar32 ucs4)
Returns whether 'fcs' contains the char 'ucs4'.
FcChar32 FcCharSetCount (const FcCharSet *a)
Returns the total number of unicode chars in 'a'.
FcChar32 FcCharSetIntersectCount (const FcCharSet *a, const FcCharSet
*b)
Returns the number of chars that are in both 'a' and 'b'.
FcChar32 FcCharSetSubtractCount (const FcCharSet *a, const FcCharSet
*b)
Returns the number of chars that are in 'a' but not in 'b'.
FcBool FcCharSetIsSubset (const FcCharSet *a, const FcCharSet *b)
Returns whether 'a' is a subset of 'b'.
FcChar32 FcCharSetFirstPage (const FcCharSet *a, FcChar32
[FC_CHARSET_MAP_SIZE], FcChar32 *next)
Builds an array of bits marking the first page of Unicode cover-
age of 'a'. Returns the base of the array. 'next' contains the
next page in the font.
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 possi-
ble 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.
void FcValueDestroy (FcValue v)
Frees any memory referenced by `v'. Values of type FcType-
String, FcTypeMatrix and FcTypeCharSet reference memory, the
other types do not.
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.
FcPattern *FcPatternCreate (void)
Creates a pattern with no properties; used to build patterns
from scratch.
void FcPatternDestroy (FcPattern *p)
Destroys a pattern, in the process destroying all related val-
ues.
FcBool FcPatternEqual (const FcPattern *pa, const FcPattern *pb);
Returns whether 'pa' and 'pb' are exactly alike.
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'.
FcChar32 FcPatternHash (const FcPattern *p)
Returns a 32-bit number which is the same for any two patterns
which are exactly alike.
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 refer-
ence to any application-supplied data structure.
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'.
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.
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.
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 ver-
ify 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.
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:
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.
FcBool FcPatternDel (FcPattern *p, const char *object)
Deletes all values associated with the property `object',
returning whether the property existed or not.
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.
void FcDefaultSubstitute (FcPattern *pattern)
Supplies default values for underspecified font patterns:
o Patterns without a specified style or weight are set to
Medium
o Patterns without a specified style or slant are set to
Roman
o Patterns without a specified pixel size are given one
computed from any specified point size (default 12), dpi
(default 75) and scale (default 1).
FcPattern *FcNameParse (const char *name)
Converts 'name' from the standard text format described above
into a pattern.
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.
FcFontSet *FcFontSetCreate (void)
Creates an empty font set.
void FcFontSetDestroy (FcFontSet *s);
Destroys a font set. Note that this destroys any referenced
patterns as well.
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.
FcObjectSet *FcObjectSetCreate (void)
Creates an empty set.
FcBool FcObjectSetAdd (FcObjectSet *os, const char *object)
Adds a proprety name to the set.
void FcObjectSetDestroy (FcObjectSet *os)
Destroys an object set.
FcObjectSet *FcObjectSetBuild (const char *first, ...)
FcObjectSet *FcObjectSetVaBuild (const char *first, va_list va)
These build an object set from a null-terminated list of prop-
erty names.
FcObjectType
Provides for applcation-specified font name object types so that new
pattern elements can be generated from font names.
FcBool FcNameRegisterObjectTypes (const FcObjectType *types, int ntype)
Register 'ntype' new object types.
FcBool FcNameUnregisterObjectTypes (const FcObjectType *types, int
ntype)
Unregister 'ntype' object types.
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.
FcBool FcNameRegisterConstants (const FcConstant *consts, int nconsts)
Register 'nconsts' new symbolic constants.
FcBool FcNameUnregisterConstants (const FcConstant *consts, int ncon-
sts)
Unregister 'nconsts' symbolic constants.
const FcConstant *FcNameGetConstant (FcChar8 *string)
Return the FcConstant structure related to symbolic constant
'string'.
FcBool FcNameConstant (FcChar8 *string, int *result);
Returns whether a symbolic constant with name 'string' is regis-
tered, 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 signifi-
cantly more accurate CharSet for applications.
FcBlanks *FcBlanksCreate (void)
Creates an empty FcBlanks object.
void FcBlanksDestroy (FcBlanks *b)
Destroys an FcBlanks object, freeing any associated memory.
FcBool FcBlanksAdd (FcBlanks *b, FcChar32 ucs4)
Adds a single character to an FcBlanks object, returning FcFalse
if this process ran out of memory.
FcBool FcBlanksIsMember (FcBlanks *b, FcChar32 ucs4)
Returns whether the specified FcBlanks object contains the indi-
cated Unicode value.
FcConfig
An FcConfig object holds the internal representation of a configura-
tion. There is a default configuration which applications may use by
passing 0 to any function using the data within an FcConfig.
FcConfig *FcConfigCreate (void)
Creates an empty configuration.
void FcConfigDestroy (FcConfig *config)
Destroys a configuration and any data associated with it. Note
that calling this function with the return from FcConfigGetCur-
rent will place the library in an indeterminate state.
FcBool FcConfigSetCurrent (FcConfig *config)
Sets the current default configuration to 'config'. Implicitly
calls FcConfigBuildFonts if necessary, returning FcFalse if that
call fails.
FcConfig *FcConfigGetCurrent (void)
Returns the current default configuration.
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.
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.
FcStrList *FcConfigGetConfigDirs (FcConfig *config)
Returns the list of font directories specified in the configura-
tion files for 'config'. Does not include any subdirectories.
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.
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.
char *FcConfigGetCache (FcConfig *config)
Returns the name of the file used to store per-user font infor-
mation.
FcFontSet *FcConfigGetFonts (FcConfig *config, FcSetName set)
Returns one of the two sets of fonts from the configuration as
specified by 'set'.
FcBlanks *FcConfigGetBlanks (FcConfig *config)
Returns the FcBlanks object associated with the given configura-
tion, if no blanks were present in the configuration, this func-
tion will return 0.
int FcConfigGetRescanInverval (FcConfig *config)
Returns the interval between automatic checks of the configura-
tion (in seconds) specified in 'config'. The configuration is
checked during a call to FcFontList when this interval has
passed since the last check.
FcBool FcConfigSetRescanInverval (FcConfig *config, int rescanInterval)
Sets the rescan interval; returns FcFalse if an error occurred.
FcBool FcConfigAppFontAddFile (FcConfig *config, const char *file)
Adds an application-specific font to the configuration.
FcBool FcConfigAppFontAddDir (FcConfig *config, const char *dir)
Scans the specified directory for fonts, adding each one found
to the application-specific set of fonts.
void FcConfigAppFontClear (FcConfig *config)
Clears the set of application-specific fonts.
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 opera-
tions are applied, else if 'kind' is FcMatchFont, those tagged
as font operations are applied and p_pat is used for <test> ele-
ments with target=pattern.
FcBool FcConfigSubstitute (FcConfig *config, FcPattern *p, FcMatchKind
kind)
Calls FcConfigSubstituteWithPat setting p_pat to NULL.
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.
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 FcFontSet-
Destroy.
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.
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.
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. Other-
wise 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 initial-
ized.
FcConfig *FcInitLoadConfig (void)
Loads the default configuration file and returns the resulting
configuration. Does not load any font information.
FcConfig *FcInitLoadConfigAndFonts (void)
Loads the default configuration file and builds information
about the available fonts. Returns the resulting configuration.
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.
int FcGetVersion (void)
Returns the version number of the library.
FcBool FcInitReinitialize (void)
Forces the default configuration file to be reloaded and resets
the default configuration.
FcBool FcInitBringUptoDate (void)
Checks the rescan interval in the default configuration, check-
ing 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.
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 atomi-
cally replaced so that reading process always see a consistent
and complete file without the need to lock for reading.
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.
FcChar8 *FcAtomicNewFile (FcAtomic *atomic)
Returns the filename for writing a new version of the file ref-
erenced by 'atomic'.
FcChar8 *FcAtomicOrigFile (FcAtomic *atomic)
Returns the file refernced by 'atomic'.
FcBool FcAtomicReplaceOrig (FcAtomic *atomic)
Replaces the original file referenced by 'atomic' with the new
file.
void FcAtomicDeleteNew (FcAtomic *atomic)
Deletes the new file.
void FcAtomicUnlock (FcAtomic *atomic)
Unlocks the file.
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.
FT_UInt FcFreeTypeCharIndex (FT_Face face, FcChar32 ucs4)
Maps a Unicode char to a glyph index. This function uses infor-
mation 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.
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.
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
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
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'.
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'.
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'.
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 scan-
ning.
FcStrSet *FcStrSetCreate (void)
Create an empty set.
FcBool FcStrSetMember (FcStrSet *set, const FcChar8 *s)
Returns whether 's' is a member of 'set'.
FcBool FcStrSetAdd (FcStrSet *set, const FcChar8 *s)
Adds a copy of 's' to 'set'.
FcBool FcStrSetAddFilename (FcStrSet *set, const FcChar8 *s)
Adds a copy 's' to 'set', The copy is created with FcStrCopy-
Filename so that leading '~' values are replaced with the value
of the HOME environment variable.
FcBool FcStrSetDel (FcStrSet *set, const FcChar8 *s)
Removes 's' from 'set', returning FcTrue if 's' was a member
else FcFalse.
void FcStrSetDestroy (FcStrSet *set)
Destroys 'set'.
FcStrList *FcStrListCreate (FcStrSet *set)
Creates an enumerator to list the strings in 'set'.
FcChar8 *FcStrListNext (FcStrList *list)
Returns the next string in 'set'.
void FcStrListDone (FcStrList *list)
Destroys the enumerator 'list'.
String utilities
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.
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.
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 uni-
code char counted. The return value indicates whether 'src' is
a well-formed UTF8 string.
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'.
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.
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.
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.
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 oper-
ate properly with UTF8 encoded strings, although it does not
check for well formed strings.
FcChar8 *FcStrDirname (const FcChar8 *file)
Returns the directory containing 'file'.
FcChar8 *FcStrBasename (const FcChar8 *file)
Returns the filename of 'file' stripped of any leading directory
names.
CONFIGURATION FILE FORMAT
Configuration files for fontconfig are stored in XML format; this for-
mat makes external configuration tools easier to write and ensures that
they will generate syntactically correct configuration files. As XML
files are plain text, they can also be manipulated by the expert user
using a text editor.
The fontconfig document type definition resides in the external entity
"fonts.dtd"; this is normally stored in the default font configuration
directory (/etc/fonts). Each configuration file should contain the
following structure:
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
...
</fontconfig>
<fontconfig>
This is the top level element for a font configuration and can contain
<dir>, <cache>, <include>, <match> and <alias> elements in any order.
<dir>
This element contains a directory name which will be scanned for font
files to include in the set of available fonts.
<cache>
This element contains a file name for the per-user cache of font infor-
mation. If it starts with '~', it refers to a file in the users home
directory. This file is used to hold information about fonts that
isn't present in the per-directory cache files. It is automatically
maintained by the fontconfig library. The default for this file is
``~/.fonts.cache-<version>'', where <version> is the font configuration
file version number (currently 1).
<include ignore_missing="no">
This element contains the name of an additional configuration file.
When the XML datatype is traversed by FcConfigParse, the contents of
the file will also be incorporated into the configuration by passing
the filename to FcConfigLoadAndParse. If 'ignore_missing' is set to
"yes" instead of the default "no", a missing file will elicit no warn-
ing message from the library.
<config>
This element provides a place to consolodate additional configuration
information. <config> can contain <blank> and <rescan> elements in any
order.
<blank>
Fonts often include "broken" glyphs which appear in the encoding but
are drawn as blanks on the screen. Within the <blank> element, place
each Unicode characters which is supposed to be blank in an <int> ele-
ment. Characters outside of this set which are drawn as blank will be
elided from the set of characters supported by the font. <b
<rescan>
The <rescan> element holds an <int> element which indicates the default
interval between automatic checks for font configuration changes.
Fontconfig will validate all of the configuration files and directories
and automatically rebuild the internal datastructures when this inter-
val passes.
<match target="pattern">
This element holds first a (possibly empty) list of <test> elements and
then a (possibly empty) list of <edit> elements. Patterns which match
all of the tests are subjected to all the edits. If 'target' is set to
"font" instead of the default "pattern", then this element applies to
the font name resulting from a match rather than a font pattern to be
matched.
<test qual="any" name="property" compare="eq">
This element contains a single value which is compared with the pattern
property "property" (substitute any of the property names seen above).
'compare' can be one of "eq", "not_eq", "less", "less_eq", "more", or
"more_eq". 'qual' may either be the default, "any", in which case the
match succeeds if any value associated with the property matches the
test value, or "all", in which case all of the values associated with
the property must match the test value.
<edit name="property" mode="assign" binding="weak">
This element contains a list of expression elements (any of the value
or operator elements). The expression elements are evaluated at run-
time and modify the property "property". The modification depends on
whether "property" was matched by one of the associated <test> ele-
ments, if so, the modification may affect the first matched value. Any
values inserted into the property are given the indicated binding.
'mode' is one of:
Mode Operation with match Operation without match
--------------------------------------------------
"assign" Replace matching value Replace all values
"assign_replace" Replace all values Replace all values
"prepend" Insert before matching value Insert at head of list
"prepend_first" Insert at head of listInsert at head of list
"append" Append after matching value Append at end of list
"append_last" Append at end of listAppend at end of list
<int>
<double>
<string>
<bool>
These elements hold a single value of the indicated type. <bool> ele-
ments hold either true or false.
<matrix>
This element holds the four <double> elements of an affine transforma-
tion.
<name>
Holds a property name. Evaluates to the first value from the property
of the font, not the pattern.
<const>
Holds the name of a constant; these are always integers and serve as
symbolic names for common font values:
Constant Property CPP symbol
------------------------------
light weight FC_WEIGHT_LIGHT
medium weight FC_WEIGHT_MEDIUM
demibold weight FC_WEIGHT_DEMIBOLD
bold weight FC_WEIGHT_BOLD
black weight FC_WEIGHT_BLACK
roman slant FC_SLANT_ROMAN
italic slant FC_SLANT_ITALIC
oblique slant FC_SLANT_OBLIQUE
proportional spacing FC_PROPORTIONAL
mono spacing FC_MONO
charcell spacing FC_CHARCELL
unknown rgba FC_RGBA_UNKNOWN
rgb rgba FC_RGBA_RGB
bgr rgba FC_RGBA_BGR
vrgb rgba FC_RGBA_VRGB
vbgr rgba FC_RGBA_VBGR
none rgba FC_RGBA_NONE
<or>
<and>
<plus>
<minus>
<times>
<divide>
These elements perform the specified operation on a list of expression
elements. <or> and <and> are boolean, not bitwise.
<eq>
<not_eq>
<less>
<less_eq>
<more>
<more_eq>
These elements compare two values, producing a boolean result.
<not>
Inverts the boolean sense of its one expression element
<if>
This element takes three expression elements; if the value of the first
is true, it produces the value of the second, otherwise it produces the
value of the third.
<alias>
Alias elements provide a shorthand notation for the set of common match
operations needed to substitute one font family for another. They con-
tain a <family> element followed by optional <prefer>, <accept> and
<default> elements. Fonts matching the <family> element are edited to
prepend the list of <prefer>ed families before the matching <family>,
append the <accept>able familys after the matching <family> and append
the <default> families to the end of the family list.
<family>
Holds a single font family name
<prefer>
<accept>
<default>
These hold a list of <family> elements to be used by the <alias> ele-
ment.
EXAMPLE CONFIGURATION FILE
System configuration file
This is an example of a system-wide configuration file
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<!-- /etc/fonts/fonts.conf file to configure system font access -->
<fontconfig>
<!--
Find fonts in these directories
-->
<dir>/usr/X11R6/lib/X11/fonts/truetype</dir>
<dir>/usr/X11R6/lib/X11/fonts/Type1</dir>
<!--
Accept deprecated 'mono' alias, replacing it with 'monospace'
-->
<match target="pattern">
<test qual="any" name="family"><string>mono</string></test>
<edit name="family" mode="assign"><string>monospace</string></edit>
</match>
<!--
Names not including any well known alias are given 'sans'
-->
<match target="pattern">
<test qual="all" name="family" mode="not_eq">sans</test>
<test qual="all" name="family" mode="not_eq">serif</test>
<test qual="all" name="family" mode="not_eq">monospace</test>
<edit name="family" mode="append_last"><string>sans</string></edit>
</match>
<!--
Load per-user customization file, but don't complain
if it doesn't exist
-->
<include ignore_missing="yes">~/.fonts.conf</include>
<!--
Alias well known font names to available TrueType fonts.
These substitute TrueType faces for similar Type1
faces to improve screen appearance.
-->
<alias>
<family>Times</family>
<prefer><family>Times New Roman</family></prefer>
<default><family>serif</family></default>
</alias>
<alias>
<family>Helvetica</family>
<prefer><family>Verdana</family></prefer>
<default><family>sans</family></default>
</alias>
<alias>
<family>Courier</family>
<prefer><family>Courier New</family></prefer>
<default><family>monospace</family></default>
</alias>
<!--
Provide required aliases for standard names
Do these after the users configuration file so that
any aliases there are used preferentially
-->
<alias>
<family>serif</family>
<prefer><family>Times New Roman</family></prefer>
</alias>
<alias>
<family>sans</family>
<prefer><family>Verdana</family></prefer>
</alias>
<alias>
<family>monospace</family>
<prefer><family>Andale Mono</family></prefer>
</alias>
</fontconfig>
User configuration file
This is an example of a per-user configuration file that lives in
~/.fonts.conf
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<!-- ~/.fonts.conf for per-user font configuration -->
<fontconfig>
<!--
Private font directory
-->
<dir>~/misc/fonts</dir>
<!--
use rgb sub-pixel ordering to improve glyph appearance on
LCD screens. Changes affecting rendering, but not matching
should always use target="font".
-->
<match target="font">
<edit name="rgba" mode="assign"><const>rgb</const></edit>
</match>
</fontconfig>
FILES
fonts.conf contains configuration information for the fontconfig
library consisting of directories to look at for font information as
well as instructions on editing program specified font patterns before
attempting to match the available fonts. It is in xml format.
fonts.dtd is a DTD that describes the format of the configuration
files.
local.conf is sourced by the default system-wide fonts.conf file. Note
that the normal 'make install' procedure for XFree86 is to replace any
existing fonts.conf file with the new version. Place any local cus-
tomizations in local.conf which this file references.
~/.fonts.conf is the conventional location for per-user font configura-
tion, although the actual location is specified in the global
fonts.conf file.
~/.fonts.cache-* is the conventional repository of font information
that isn't found in the per-directory caches. This file is automati-
cally maintained by fontconfig.
AUTHOR
Keith Packard, member of the XFree86 Project, Inc.
XFree86 Version 1.0 fontconfig(3)
Mac OS X 10.4 X11 - Generated Sat Apr 30 05:11:30 CDT 2005