Table of Contents
fontconfig - Font configuration and customization
library
#include <fontconfig/fontconfig.h>
#include <fontconfig/fcfreetype.h>
#include <fontconfig/fcxml.h>
Fontconfig is a library designed to provide system-wide font
configuration, customization and application access.
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.
The
configuration module consists of the FcConfig datatype, libxml2 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 make simplify and regularize font installation and customization.
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
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 Bool Use vertical layout
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
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 Scale factor for point->pixel conversions
dpi FC_DPI Double Target dots per inch
rgba FC_RGBA Int rgb, bgr, vrgb, vbgr - 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 language groups this font is designed for
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 consists 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 values 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, antialias, family,
spacing, pixelsize, style, slant, weight, rasterizer and outline. This
list is in priority order -- results of comparing earlier elements of this
list weigh more heavily than later elements.
The pattern representing that
font is augmented to include any properties found in the pattern but not
found in the font itself; this permits 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 pattern. This modified pattern is returned to the application.
The return value contains sufficient information to locate and rasterize
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.
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 1 The users preferred monospace font
with artificial obliquing
- 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;
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 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.
- 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.
- 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
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 FcMatrix *b)
- Multiplies 'a' and
'b' together, placing the result in
- 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.
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.
- 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 anything 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'.
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.
- void FcValueDestroy (FcValue v)
- Frees any memory referenced
by `v'. Values of type FcTypeString, 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.
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 values.
- 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.
- 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 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.
- 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 (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:
·- 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).
- 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.
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.
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 property names.
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.
- 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
indicated Unicode value.
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.
- 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 FcConfigGetCurrent 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 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.
- char **FcConfigGetDirs
(FcConfig *config)
- Returns the list of font directories specified in 'config'.
- char **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 information.
- 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 configuration, if no blanks were present in the
configuration, this function will return 0.
- 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 FcConfigSubstitute
(FcConfig *config, FcPattern *p, 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.
- 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; otherwise the results will be
less useful.
- 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. 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.
These
functions provide some control over how the library is initialized.
- FcBool
FcInitConfig (void)
- Initializes the default configuration using the default
configuration file
- FcBool FcInitFonts (void)
- Initializes the set of fonts
available in the default configuration
- FcBool FcInit (void)
- Calls FcInitConfig
and FcInitFonts to completely initialize the default configuration.
#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 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.
- 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 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'.
#include <fontconfig/fcxml.h>
These functions expose the libxml2 datatypes used for font configuration.
- xmlDocPtr FcConfigLoad (const char *file)
- Loads a configuration file mapping
'file' into a filename with FcConfigFilename. This doesn't load a complete
configuration as any include files referenced from 'file' will not be loaded.
- FcBool FcConfigParse (FcConfig *config, xmlDocPtr doc)
- Walks the given
configuration and constructs the internal representation in with FcConfigLoad
and also parsed.
- FcBool FcFileScan (FcFontSet
*set, 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'.
- FcBool FcDirScan (FcFontSet *set, 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'.
- FcBool FcDirSave (FcFontSet *set, const char *dir)
- Creates
the per-directory cache file for 'dir' and populates it with the fonts in
'set'.
- 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.
- FcBool
FcUtf8Len (FcChar8 *string, int len, int *nchar, int *wchar)
- Counts the
number of Unicode chars in 'len' bytes of 'string'. 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 UTF8 string.
- char *FcStrCopy (const char *s)
- Allocates
memory, copies 's' and returns the resulting buffer. Yes, this is
- 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.
Configuration files for fontconfig
are stored in XML format; this format 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>
This is the top level element for a font configuration and can
contain <dir>, <cache>, <include>, <match> and <alias> elements in any order.
This
element contains a directory name which will be scanned for font files
to include in the set of available fonts.
This element contains a
file name for the per-user cache of font information. 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''.
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 warning message from the library.
This
element holds first a (possibly empty) list of tests and then a (possibly
empty) list of edits. 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.
This
element contains a single value which is compared with the pattern property
"property" (substitute any of the property names seen above). "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.
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> elements, if so, the modification may affect
the first matched value. '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 list Insert at head of list
"append" Append after matching value Append at end of list
"append_last" Append at end of list Append at end of list
These elements hold a single value of the indicated
type. <bool> elements hold either true or false.
This element holds
the four <double> elements of an affine transformation.
Holds a property
name. Evaluates to the first value from the property of the font, not the
pattern.
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
rgb rgba FC_RGBA_RGB
bgr rgba FC_RGBA_BGR
vrgb rgba FC_RGBA_VRGB
vbgr rgba FC_RGBA_VBGR
These elements perform the specified operation
on a list of expression elements. <or> and <and> are boolean, not bitwise.
These
elements compare two values, producing a boolean result.
Inverts the
boolean sense of its one expression element
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
elements provide a shorthand notation for the set of common match operations
needed to substitute one font family for another. They contain 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.
Holds a single font family name
These hold
a list of <family> elements to be used by the <alias> element.
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>
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>
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.
~/.fonts.conf is the conventional
location for per-user font configuration, 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 automatically maintained by fontconfig.
Keith Packard,
member of the XFree86 Project, Inc.
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