Copyright © 2002 Keith Packard
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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, libexpat and FcConfigParse which walks over an XML tree and amends a configuration with data found within. From an external perspective, configuration of the library consists of generating a valid XML tree and feeding that to FcConfigParse. The only other mechanism provided to applications for changing the running configuration is to add fonts and directories to the list of application-provided font files.
The intent is to make font configurations relatively static, and shared by as many applications as possible. It is hoped that this will lead to more stable font selection when passing names from one application to another. XML was chosen as a configuration file format because it provides a format which is easy for external agents to edit while retaining the correct structure and syntax.
Font configuration is separate from font matching; applications needing to do their own matching can access the available fonts from the library and perform private matching. The intent is to permit applications to pick and choose appropriate functionality from the library instead of forcing them to choose between this library and a private configuration mechanism. The hope is that this will ensure that configuration of fonts for all applications can be centralized in one place. Centralizing font configuration will simplify and regularize font installation and customization.
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 application's rendering mechanism.
Property Definitions
Property C Preprocessor Symbol Type Description
----------------------------------------------------
family FC_FAMILY String Font family names
familylang FC_FAMILYLANG String Language corresponding to
each family name
style FC_STYLE String Font style. Overrides weight
and slant
stylelang FC_STYLELANG String Language corresponding to
each style name
fullname FC_FULLNAME String Font face full name where
different from family and
family + style
fullnamelang FC_FULLNAMELANG String Language corresponding to
each fullname
slant FC_SLANT Int Italic, oblique or roman
weight FC_WEIGHT Int Light, medium, demibold,
bold or black
width FC_WIDTH Int Condensed, normal or expanded
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, dual-width,
monospace or charcell
foundry FC_FOUNDRY String Font foundry name
antialias FC_ANTIALIAS Bool Whether glyphs can be
antialiased
hintstyle FC_HINT_STYLE Int Automatic hinting style
hinting FC_HINTING Bool Whether the rasterizer should
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 (deprecated)
file FC_FILE String The filename holding the font
relative to the config's sysroot
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 (deprecated)
outline FC_OUTLINE Bool Whether the glyphs are outlines
scalable FC_SCALABLE Bool Whether the glyphs are outlines or have color
dpi FC_DPI Double Target dots per inch
rgba FC_RGBA Int unknown, rgb, bgr, vrgb,
vbgr, none - subpixel geometry
scale FC_SCALE Double Scale factor for point->pixel
conversions (deprecated)
minspace FC_MINSPACE Bool Eliminate leading from line
spacing
matrix FC_MATRIX Matrix Hold an affine transformation
charset FC_CHARSET CharSet Unicode chars encoded by
the font
lang FC_LANG LangSet Set of RFC-3066-style
languages this font supports
fontversion FC_FONTVERSION Int Version number of the font
capability FC_CAPABILITY String List of layout capabilities in
the font
fontformat FC_FONTFORMAT String String name of the font format
embolden FC_EMBOLDEN Bool Rasterizer should
synthetically embolden the font
embeddedbitmap FC_EMBEDDED_BITMAP Bool Use the embedded bitmap instead
of the outline
decorative FC_DECORATIVE Bool Whether the style is a decorative
variant
lcdfilter FC_LCD_FILTER Int Type of LCD filter
namelang FC_NAMELANG String Language name to be used for the
default value of familylang,
stylelang and fullnamelang
fontfeatures FC_FONT_FEATURES String List of extra feature tags in
OpenType to be enabled
prgname FC_PRGNAME String Name of the running program
hash FC_HASH String SHA256 hash value of the font data
with "sha256:" prefix (deprecated)
postscriptname FC_POSTSCRIPT_NAME String Font name in PostScript
color FC_COLOR Bool Whether any glyphs have color
symbol FC_SYMBOL Bool Whether font uses MS symbol-font encoding
fontvariations FC_FONT_VARIATIONS String comma-separated string of axes in variable font
variable FC_VARIABLE Bool Whether font is Variable Font
fonthashint FC_FONT_HAS_HINT Bool Whether font has hinting
order FC_ORDER Int Order number of the font
desktop FC_DESKTOP_NAME String Current desktop name
namedinstance FC_NAMED_INSTANCE Bool Whether font is a named instance
fontwarapper FC_FONT_WRAPPER String The font wrapper format
|
Fontconfig uses abstract data types to hide internal implementation details for most data structures. A few structures are exposed where appropriate.
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 C preprocessor symbols: FcFalse or FcTrue.
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;
|
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.
An FcLangSet is an abstract type that holds the set of languages supported by a font. Operations to build and compare these sets are provided. These are computed for a font based on orthographic information built into the fontconfig library. Fontconfig has orthographies for all of the ISO 639-1 languages except for MS, NA, PA, PS, QU, RN, RW, SD, SG, SN, SU and ZA. If you have orthographic information for any of these languages, please submit them.
An FcLangResult is an enumeration used to return the results of comparing two language strings or FcLangSet objects. FcLangEqual means the objects match language and territory. FcLangDifferentTerritory means the objects match in language but differ in territory. FcLangDifferentLang means the objects differ in language.
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 FcLangSet *l;
const FcRange *r;
} u;
} FcValue;
|
FcValue Members
Type Union member Datatype
--------------------------------
FcTypeVoid (none) (none)
FcTypeInteger i int
FcTypeDouble d double
FcTypeString s FcChar8 *
FcTypeBool b b
FcTypeMatrix m FcMatrix *
FcTypeCharSet c FcCharSet *
FcTypeFTFace f void * (FT_Face)
FcTypeLangSet l FcLangSet *
FcTypeRange r FcRange *
|
An 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. An FcPatternIter is used during iteration to access properties in FcPattern.
typedef struct _FcFontSet {
int nfont;
int sfont;
FcPattern **fonts;
} FcFontSet;
|
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.
typedef struct _FcObjectSet {
int nobject;
int sobject;
const char **objects;
} FcObjectSet;
|
typedef struct _FcObjectType {
const char *object;
FcType type;
} FcObjectType;
|
typedef struct _FcConstant {
const FcChar8 *name;
const char *object;
int value;
} FcConstant;
|
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.
FcBlanks is deprecated and should not be used in newly written code. It is still accepted by some functions for compatibility with older code but will be removed in the future.
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.
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 particular set use one of the FcSetName enumerated values.
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.
Used as a return type for functions manipulating FcPattern objects.
FcResult Values
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
FcResultOutOfMemory malloc failed
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Used for locking access to configuration files. Provides a safe way to update configuration files.
Holds information about the fonts contained in a single directory. Normal applications need not worry about this as caches for font access are automatically managed by the library. Applications dealing with cache management may want to use some of these objects in their work, however the included 'fc-cache' program generally suffices for all of that.
These are grouped by functionality, often using the main data type being manipulated.
These functions provide some control over how the library is initialized.
Loads the default configuration file and returns the resulting configuration. Does not load any font information.
Loads the default configuration file and builds information about the available fonts. Returns the resulting configuration.
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.
Frees all data structures allocated by previous calls to fontconfig functions. Fontconfig returns to an uninitialized state, requiring a new call to one of the FcInit functions before any other fontconfig function may be called.
Forces the default configuration file to be reloaded and resets the default configuration. Returns FcFalse if the configuration cannot be reloaded (due to configuration file errors, allocation failures or other issues) and leaves the existing configuration unchanged. Otherwise returns FcTrue.
An FcPattern is an opaque type that holds both patterns to match against the available fonts, as well as the information about each font.
Copy a pattern, returning a new pattern that matches p. Each pattern may be modified without affecting the other.
Add another reference to p. Patterns are freed only when the reference count reaches zero.
Decrement the pattern reference count. If all references are gone, destroys the pattern, in the process destroying all related values.
Returns a new pattern that only has those objects from p that are in os. If os is NULL, a duplicate of p is returned.
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 beginning. `value' is saved (with FcValueSave) when inserted into the pattern so that the library retains no reference to any application-supplied data structure.
FcPatternAddWeak is essentially the same as FcPatternAdd except that any values added to the list have binding weak instead of strong.
#include <fontconfig/fontconfig.h>
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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 FcChar8 *s);
FcBool FcPatternAddMatrix(FcPattern *p, const char *object, const FcMatrix *m);
FcBool FcPatternAddCharSet(FcPattern *p, const char *object, const FcCharSet *c);
FcBool FcPatternAddBool(FcPattern *p, const char *object, FcBool b);
FcBool FcPatternAddFTFace(FcPattern *p, const char *object, const FT_Face f);
FcBool FcPatternAddLangSet(FcPattern *p, const char *object, const FcLangSet *l);
FcBool FcPatternAddRange(FcPattern *p, const char *object, const FcRange *r);
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. FcPatternAddRange are available since 2.11.91.
Returns in v the id'th value and b binding for that 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.
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.
#include <fontconfig/fontconfig.h>
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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, FcChar8 **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);
FcResult FcPatternGetFTFace(FcPattern *p, const char *object, int n, FT_Face *f);
FcResult FcPatternGetLangSet(FcPattern *p, const char *object, int n, FcLangSet **l);
FcResult FcPatternGetRange(FcPattern *p, const char *object, int n, FcRange **r);
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. FcPatternGetRange are available since 2.11.91.
Builds a pattern using a list of objects, types and values. Each value to be entered in the pattern is specified with three arguments:
Object name, a string describing the property to be added.
Object type, one of the FcType enumerated values
Value, not an FcValue, but the raw type as passed to any of the FcPatternAdd<type> functions. Must match the type of the second argument.
The argument list is terminated by a null object name, no object type nor value need be passed for this. The values are added to `pattern', if `pattern' is null, a new pattern is created. In either case, the pattern is returned. Example
pattern = FcPatternBuild (0, FC_FAMILY, FcTypeString, "Times", (char *) 0); |
FcPatternVaBuild is used when the arguments are already in the form of a varargs value. FcPatternVapBuild is a macro version of FcPatternVaBuild which returns its result directly in the result variable.
Deletes all values associated with the property `object', returning whether the property existed or not.
Removes the value associated with the property `object' at position `id', returning whether the property existed and had a value at that position or not.
Initialize iter with the first iterator in p. If there are no objects in p, iter will not have any valid data.
Set iter to point to the next object in p and returns FcTrue if iter has been changed to the next object. returns FcFalse otherwise.
Return FcTrue if both i1 and i2 point to same object and contains same values. return FcFalse otherwise.
Returns the number of the values in the object which iter point to. if iter isn't valid, returns 0.
Returns in v the id'th value which iter point to. also binding to b if given. The value returned is not a copy, but rather refers to the data stored within the pattern directly. Applications must not free this value.
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.
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).
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 using free().
Converts given pattern pat into text described by the format specifier format. The return value refers to newly allocated memory which should be freed by the caller using free(), or NULL if format is invalid.
The format is loosely modeled after printf-style format string. The format string is composed of zero or more directives: ordinary characters (not "%"), which are copied unchanged to the output stream; and tags which are interpreted to construct text from the pattern in a variety of ways (explained below). Special characters can be escaped using backslash. C-string style special characters like \n and \r are also supported (this is useful when the format string is not a C string literal). It is advisable to always escape curly braces that are meant to be copied to the output as ordinary characters.
Each tag is introduced by the character "%", followed by an optional minimum field width, followed by tag contents in curly braces ({}). If the minimum field width value is provided the tag will be expanded and the result padded to achieve the minimum width. If the minimum field width is positive, the padding will right-align the text. Negative field width will left-align. The rest of this section describes various supported tag contents and their expansion.
A simple tag is one where the content is an identifier. When simple tags are expanded, the named identifier will be looked up in pattern and the resulting list of values returned, joined together using comma. For example, to print the family name and style of the pattern, use the format "%{family} %{style}\n". To extend the family column to forty characters use "%-40{family}%{style}\n".
Simple tags expand to list of all values for an element. To only choose one of the values, one can index using the syntax "%{elt[idx]}". For example, to get the first family name only, use "%{family[0]}".
If a simple tag ends with "=" and the element is found in the pattern, the name of the element followed by "=" will be output before the list of values. For example, "%{weight=}" may expand to the string "weight=80". Or to the empty string if pattern does not have weight set.
If a simple tag starts with ":" and the element is found in the pattern, ":" will be printed first. For example, combining this with the =, the format "%{:weight=}" may expand to ":weight=80" or to the empty string if pattern does not have weight set.
If a simple tag contains the string ":-", the rest of the the tag contents will be used as a default string. The default string is output if the element is not found in the pattern. For example, the format "%{:weight=:-123}" may expand to ":weight=80" or to the string ":weight=123" if pattern does not have weight set.
A count tag is one that starts with the character "#" followed by an element name, and expands to the number of values for the element in the pattern. For example, "%{#family}" expands to the number of family names pattern has set, which may be zero.
A sub-expression tag is one that expands a sub-expression. The tag contents are the sub-expression to expand placed inside another set of curly braces. Sub-expression tags are useful for aligning an entire sub-expression, or to apply converters (explained later) to the entire sub-expression output. For example, the format "%40{{%{family} %{style}}}" expands the sub-expression to construct the family name followed by the style, then takes the entire string and pads it on the left to be at least forty characters.
A filter-out tag is one starting with the character "-" followed by a comma-separated list of element names, followed by a sub-expression enclosed in curly braces. The sub-expression will be expanded but with a pattern that has the listed elements removed from it. For example, the format "%{-size,pixelsize{sub-expr}}" will expand "sub-expr" with pattern sans the size and pixelsize elements.
A filter-in tag is one starting with the character "+" followed by a comma-separated list of element names, followed by a sub-expression enclosed in curly braces. The sub-expression will be expanded but with a pattern that only has the listed elements from the surrounding pattern. For example, the format "%{+family,familylang{sub-expr}}" will expand "sub-expr" with a sub-pattern consisting only the family and family lang elements of pattern.
A conditional tag is one starting with the character "?" followed by a comma-separated list of element conditions, followed by two sub-expression enclosed in curly braces. An element condition can be an element name, in which case it tests whether the element is defined in pattern, or the character "!" followed by an element name, in which case the test is negated. The conditional passes if all the element conditions pass. The tag expands the first sub-expression if the conditional passes, and expands the second sub-expression otherwise. For example, the format "%{?size,dpi,!pixelsize{pass}{fail}}" will expand to "pass" if pattern has size and dpi elements but no pixelsize element, and to "fail" otherwise.
An enumerate tag is one starting with the string "[]" followed by a comma-separated list of element names, followed by a sub-expression enclosed in curly braces. The list of values for the named elements are walked in parallel and the sub-expression expanded each time with a pattern just having a single value for those elements, starting from the first value and continuing as long as any of those elements has a value. For example, the format "%{[]family,familylang{%{family} (%{familylang})\n}}" will expand the pattern "%{family} (%{familylang})\n" with a pattern having only the first value of the family and familylang elements, then expands it with the second values, then the third, etc.
As a special case, if an enumerate tag has only one element, and that element has only one value in the pattern, and that value is of type FcLangSet, the individual languages in the language set are enumerated.
A builtin tag is one starting with the character "=" followed by a builtin name. The following builtins are defined:
Expands to the result of calling FcNameUnparse() on the pattern.
Expands to the output of the default output format of the fc-match command on the pattern, without the final newline.
Expands to the output of the default output format of the fc-list command on the pattern, without the final newline.
Expands to the output of the default output format of the fc-cat command on the pattern, without the final newline.
Expands to the list of PackageKit font() tags for the pattern. Currently this includes tags for each family name, and each language from the pattern, enumerated and sanitized into a set of tags terminated by newline. Package management systems can use these tags to tag their packages accordingly.
The contents of any tag can be followed by a set of zero or more converters. A converter is specified by the character "|" followed by the converter name and arguments. The following converters are defined:
Replaces text with the results of calling FcStrBasename() on it.
Replaces text with the results of calling FcStrDirname() on it.
Replaces text with the results of calling FcStrDowncase() on it.
Escapes text for one level of shell expansion. (Escapes single-quotes, also encloses text in single-quotes.)
Escapes text such that it can be used as part of a C string literal. (Escapes backslash and double-quotes.)
Escapes text such that it can be used in XML and HTML. (Escapes less-than, greater-than, and ampersand.)
Deletes all occurrences of each of the characters in chars from the text. FIXME: This converter is not UTF-8 aware yet.
Escapes all occurrences of each of the characters in chars by prepending it by the first character in chars. FIXME: This converter is not UTF-8 aware yet.
Translates all occurrences of each of the characters in from by replacing them with their corresponding character in to. If to has fewer characters than from, it will be extended by repeating its last character. FIXME: This converter is not UTF-8 aware yet.
An FcFontSet simply holds a list of patterns; these are used to return the results of listing available fonts.
Adds a pattern to a font set. Note that the pattern is not copied before being inserted into the set. Returns FcFalse if the pattern cannot be inserted into the set (due to allocation failure). Otherwise returns FcTrue.
Selects fonts matching pattern from sets, creates patterns from those fonts containing only the objects in object_set and returns the set of unique such patterns. If config is NULL, the default configuration is checked to be up to date, and used.
Finds the font in sets most closely matching pattern and returns the result of FcFontRenderPrepare for that font and the provided pattern. This function should be called only after FcConfigSubstitute and FcDefaultSubstitute have been called for pattern; otherwise the results will not be correct. If config is NULL, the current configuration is used. Returns NULL if an error occurs during this process.
This function is useful for diagnosing font related issues, printing the complete contents of every pattern in set. The format of the output is designed to be of help to users and developers, and may change at any time.
Returns the list of fonts from sets sorted by closeness to pattern. 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 cannot modify these patterns. Instead, they should be passed, along with pattern to FcFontRenderPrepare which combines them into a complete pattern.
The FcFontSet returned by FcFontSetSort is destroyed by calling FcFontSetDestroy.
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.
Adds a property name to the set. Returns FcFalse if the property name cannot be inserted into the set (due to allocation failure). Otherwise returns FcTrue.
While the fontconfig library doesn't insist that FreeType be used as the rasterization mechanism for fonts, it does provide some convenience functions.
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.
Scans a FreeType face and returns the set of encoded Unicode chars. FcBlanks is deprecated, blanks is ignored and accepted only for compatibility with older code.
Scans a FreeType face and returns the set of encoded Unicode chars. FcBlanks is deprecated, blanks is ignored and accepted only for compatibility with older code. spacing receives the computed spacing type of the font, one of FC_MONO for a font where all glyphs have the same width, FC_DUAL, where the font has glyphs in precisely two widths, one twice as wide as the other, or FC_PROPORTIONAL where the font has glyphs of many widths.
Constructs a pattern representing the 'id'th face in 'file'. The number of faces in 'file' is returned in 'count'. FcBlanks is deprecated, blanks is ignored and accepted only for compatibility with older code.
Constructs patterns found in 'file'. If id is -1, then all patterns found in 'file' are added to 'set'. Otherwise, this function works exactly like FcFreeTypeQuery(). The number of faces in 'file' is returned in 'count'. The number of patterns added to 'set' is returned. FcBlanks is deprecated, blanks is ignored and accepted only for compatibility with older code.
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.
Frees any memory referenced by v. Values of type FcTypeString, FcTypeMatrix and FcTypeCharSet reference memory, the other types do not.
Returns a copy of v duplicating any object referenced by it so that v may be safely destroyed without harming the new value.
Prints a human-readable representation of v to stdout. The format should not be considered part of the library specification as it may change in the future.
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.
FcCharSetDestroy decrements the reference count fcs. If the reference count becomes zero, all memory referenced is freed.
FcCharSetAddChar 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.
FcCharSetDelChar deletes a single Unicode char from the set, returning FcFalse on failure, either as a result of a constant set or from running out of memory.
Makes a copy of src; note that this may not actually do anything more than increment the reference count on src.
Adds all chars in b to a. In other words, this is an in-place version of FcCharSetUnion. If changed is not NULL, then it returns whether any new chars from b were added to a. Returns FcFalse on failure, either when a is a constant set or from running out of memory.
Builds an array of bits in map marking the
first page of Unicode coverage of a.
*next is set to contains the base code point
for the next page in a. Returns the base code
point for the page, or FC_CHARSET_DONE if
a contains no pages. As an example, if
FcCharSetFirstPage returns
0x300 and fills map with
0xffffffff 0xffffffff 0x01000008 0x44300002 0xffffd7f0 0xfffffffb 0xffff7fff 0xffff0003 |
Builds an array of bits in map marking the
Unicode coverage of a for page containing
*next (see the
FcCharSetFirstPage description for details).
*next is set to contains the base code point
for the next page in a. Returns the base of
code point for the page, or FC_CHARSET_DONE if
a does not contain
*next.
DEPRECATED This function returns a bitmask in result which indicates which code points in page are included in a. FcCharSetCoverage returns the next page in the charset which has any coverage.
An FcLangSet is a set of language names (each of which include language and an optional territory). They are used when selecting fonts to indicate which languages the fonts need to support. Each font is marked, using language orthography information built into fontconfig, with the set of supported languages.
lang is added to ls. lang should be of the form Ll-Tt where Ll is a two or three letter language from ISO 639 and Tt is a territory from ISO 3166.
lang is removed from ls. lang should be of the form Ll-Tt where Ll is a two or three letter language from ISO 639 and Tt is a territory from ISO 3166.
FcLangSetCompare compares language coverage for ls_a and ls_b. If they share any language and territory pair, this function returns FcLangEqual. If they share a language but differ in which territory that language is for, this function returns FcLangDifferentTerritory. If they share no languages in common, this function returns FcLangDifferentLang.
FcLangSetContains returns FcTrue if ls_a contains every language in ls_b. ls_a will 'contain' a language from ls_b if ls_a has exactly the language, or either the language or ls_a has no territory.
Returns FcTrue if and only if ls_a supports precisely the same language and territory combinations as ls_b.
This function returns a value which depends solely on the languages supported by ls. Any language which equals ls will have the same result from FcLangSetHash. However, two langsets with the same hash value may not be equal.
FcLangSetHasLang checks whether ls supports lang. If ls has a matching language and territory pair, this function returns FcLangEqual. If ls has a matching language but differs in which territory that language is for, this function returns FcLangDifferentTerritory. If ls has no matching language, this function returns FcLangDifferentLang.
Returns a string set of the default languages according to the environment variables on the system. This function looks for them in order of FC_LANG, LC_ALL, LC_CTYPE and LANG then. If there are no valid values in those environment variables, "en" will be set as fallback.
FcMatrix structures hold an affine transformation in matrix form.
FcMatrixEqual compares matrix1 and matrix2 returning FcTrue when they are equal and FcFalse when they are not.
FcMatrixRotate rotates matrix by the angle who's sine is sin and cosine is cos. This is done by multiplying by the matrix:
cos -sin sin cos |
FcMatrixScale multiplies matrix x values by sx and y values by dy. This is done by multiplying by the matrix:
sx 0 0 dy |
An FcRange holds two variables to indicate a range in between.
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.
Add another reference to config. Configs are freed only when the reference count reaches zero. If config is NULL, the current configuration is used. In that case this function will be similar to FcConfigGetCurrent() except that it increments the reference count before returning and the user is responsible for destroying the configuration when not needed anymore.
Decrements the config reference count. If all references are gone, destroys the configuration and any data associated with it. Note that calling this function with the return from FcConfigGetCurrent will cause a new configuration to be created for use as current configuration.
Sets the current default configuration to config. Implicitly calls FcConfigBuildFonts if necessary, and FcConfigReference() to inrease the reference count in config since 2.12.0, returning FcFalse if that call fails.
Sets filter_func as a predicate function and filter out fontsets in config as desired. filter_func will be called with a font pattern and user_data only when loading caches. When config is going to be destroyed, user_data will be destroyed through destroy_data_func if it is set.
This triggers a predicate function set by FcConfigSetFontSetFilter and return FcTrue if font matches something they expect. otherwise FcFalse.
Checks all of the files related to config and returns whether any of them has been modified since the configuration was created. If config is NULL, the current configuration is used.
Return the current user's home directory, if it is available, and if using it is enabled, and NULL otherwise. See also FcConfigEnableHome).
If enable is FcTrue, then Fontconfig will use various files which are specified relative to the user's home directory (using the ~ notation in the configuration). When enable is FcFalse, then all use of the home directory in these contexts will be disabled. The previous setting of the value is returned.
Builds the set of available fonts for the given configuration. Note that any changes to the configuration after this call (through FcConfigParseAndLoad or FcConfigParseAndLoadFromMemory) have indeterminate effects. (On the other hand, application fonts can still be modified through FcConfigAppFontAddFile, FcConfigAppFontAddDir and FcConfigAppFontClear). Returns FcFalse if this operation runs out of memory. If config is NULL, the current configuration is used.
Returns the list of font directories specified in the configuration files for config. Does not include any subdirectories. If config is NULL, the current configuration is used.
Returns the list of font directories in config. This includes the configured font directories along with any directories below those in the filesystem. If config is NULL, the current configuration is used.
Returns the list of known configuration files used to generate config. If config is NULL, the current configuration is used.
With fontconfig no longer using per-user cache files, this function now simply returns NULL to indicate that no per-user file exists.
FcConfigGetCacheDirs returns a string list containing all of the directories that fontconfig will search when attempting to load a cache file for a font directory. If config is NULL, the current configuration is used.
Returns one of the two sets of fonts from the configuration as specified by set. This font set is owned by the library and must not be modified or freed. If config is NULL, the current configuration is used.
This function isn't MT-safe. FcConfigReference must be called before using this and then FcConfigDestroy when the return value is no longer referenced.
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. An interval setting of zero disables automatic checks. If config is NULL, the current configuration is used.
Sets the rescan interval. Returns FcFalse if the interval cannot be set (due to allocation failure). Otherwise returns FcTrue. An interval setting of zero disables automatic checks. If config is NULL, the current configuration is used.
Adds an application-specific font to the configuration. Returns FcFalse if the fonts cannot be added (due to allocation failure or no fonts found). Otherwise returns FcTrue. If config is NULL, the current configuration is used.
Scans the specified directory for fonts, adding each one found to the application-specific set of fonts. Returns FcFalse if the fonts cannot be added (due to allocation failure). Otherwise returns FcTrue. If config is NULL, the current configuration is used.
Clears the set of application-specific fonts. If config is NULL, the current configuration is used.
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. Returns FcFalse if the substitution cannot be performed (due to allocation failure). Otherwise returns FcTrue. If config is NULL, the current configuration is used.
Calls FcConfigSubstituteWithPat setting p_pat to NULL. Returns FcFalse if the substitution cannot be performed (due to allocation failure). Otherwise returns FcTrue. If config is NULL, the current configuration is used.
Finds the font in sets most closely matching pattern and returns the result of FcFontRenderPrepare for that font and the provided pattern. This function should be called only after FcConfigSubstitute and FcDefaultSubstitute have been called for p; otherwise the results will not be correct. If config is NULL, the current configuration is used.
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 calling FcFontSetDestroy. If config is NULL, the current configuration is used.
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 FcConfigSubstituteWithPat with kind FcMatchFont and then returned.
Selects fonts matching p, creates patterns from those fonts containing only the objects in os and returns the set of unique such patterns. If config is NULL, the default configuration is checked to be up to date, and used.
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 FONTCONFIG_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 FONTCONFIG_PATH environment variable.
The result of this function is affected by the FONTCONFIG_SYSROOT environment variable or equivalent functionality.
Walks the configuration in 'file' and constructs the internal representation in 'config'. Any include files referenced from within 'file' will be loaded and parsed. If 'complain' is FcFalse, no warning will be displayed if 'file' does not exist. Error and warning messages will be output to stderr. Returns FcFalse if some error occurred while loading the file, either a parse error, semantic error or allocation failure. Otherwise returns FcTrue. After all configuration files / strings have been loaded, with FcConfigParseAndLoad and/or FcConfigParseAndLoadFromMemory, call FcConfigBuildFonts to build the font database.
Walks the configuration in 'memory' and constructs the internal representation in 'config'. Any includes files referenced from within 'memory' will be loaded and dparsed. If 'complain' is FcFalse, no warning will be displayed if 'file' does not exist. Error and warning messages will be output to stderr. Returns FcFalse if fsome error occurred while loading the file, either a parse error, semantic error or allocation failure. Otherwise returns FcTrue. After all configuration files / strings have been loaded, with FcConfigParseAndLoad and/or FcConfigParseAndLoadFromMemory, call FcConfigBuildFonts to build the font database.
Obtains the system root directory in 'config' if available. All files (including file properties in patterns) obtained from this 'config' are relative to this system root directory.
This function isn't MT-safe. FcConfigReference must be called before using this and then FcConfigDestroy when the return value is no longer referenced.
Set 'sysroot' as the system root directory. All file paths used or created with this 'config' (including file properties in patterns) will be considered or made relative to this 'sysroot'. This allows a host to generate caches for targets at build time. This also allows a cache to be re-targeted to a different base directory if 'FcConfigGetSysRoot' is used to resolve file paths. When setting this on the current config this causes changing current config (calls FcConfigSetCurrent()).
Initialize 'iter' with the first iterator in the config file information list.
The config file information list is stored in numerical order for filenames i.e. how fontconfig actually read them.
This function isn't MT-safe. FcConfigReference must be called before using this and then FcConfigDestroy when the relevant values are no longer referenced.
Set 'iter' to point to the next node in the config file information list. If there is no next node, FcFalse is returned.
This function isn't MT-safe. FcConfigReference must be called before using FcConfigFileInfoIterInit and then FcConfigDestroy when the relevant values are no longer referenced.
Obtain the filename, the description and the flag whether it is enabled or not for 'iter' where points to current configuration file information. If the iterator is invalid, FcFalse is returned.
This function isn't MT-safe. FcConfigReference must be called before using FcConfigFileInfoIterInit and then FcConfigDestroy when the relevant values are no longer referenced.
Provides for application-specified font name object types so that new pattern elements can be generated from font names.
Provides for application-specified symbolic constants for font names.
Maps weights to and from OpenType weights.
FcWeightFromOpenTypeDouble returns an double value to use with FC_WEIGHT, from an double in the 1..1000 range, resembling the numbers from OpenType specification's OS/2 usWeight numbers, which are also similar to CSS font-weight numbers. If input is negative, zero, or greater than 1000, returns -1. This function linearly interpolates between various FC_WEIGHT_* constants. As such, the returned value does not necessarily match any of the predefined constants.
FcWeightToOpenTypeDouble is the inverse of FcWeightFromOpenType. If the input is less than FC_WEIGHT_THIN or greater than FC_WEIGHT_EXTRABLACK, returns -1. Otherwise returns a number in the range 1 to 1000.
FcWeightFromOpenType is like FcWeightFromOpenTypeDouble but with integer arguments. Use the other function instead.
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 is deprecated and should not be used in newly written code. It is still accepted by some functions for compatibility with older code but will be removed in the future.
These functions provide a safe way to update configuration files, allowing ongoing reading of the old configuration file while locked for writing and ensuring that a consistent and complete version of the configuration file is always available.
Creates a data structure containing data needed to control access to file. Writing is done to a separate file. Once that file is complete, the original configuration file is atomically replaced so that reading process always see a consistent and complete file without the need to lock for reading.
Attempts to lock the file referenced by atomic. Returns FcFalse if the file is already locked, else returns FcTrue and leaves the file locked.
Replaces the original file referenced by atomic with the new file. Returns FcFalse if the file cannot be replaced due to permission issues in the filesystem. Otherwise returns FcTrue.
These routines work with font files and directories, including font directory cache files.
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. Whether fonts are found depends on fontconfig policy as well as the current configuration. Internally, fontconfig will ignore BDF and PCF fonts which are not in Unicode (or the effectively equivalent ISO Latin-1) encoding as those are not usable by Unicode-based applications. The configuration can ignore fonts based on filename or contents of the font file itself. Returns FcFalse if any of the fonts cannot be added (due to allocation failure). Otherwise returns FcTrue.
If cache is not zero or if force is FcFalse, this function currently returns FcFalse. Otherwise, it scans an entire directory and adds all fonts found to set. Any subdirectories found are added to dirs. Calling this function does not create any cache files. Use FcDirCacheRead() if caching is desired.
This function now does nothing aside from returning FcFalse. It used to creates the per-directory cache file for dir and populates it with the fonts in set and subdirectories in dirs. All of this functionality is now automatically managed by FcDirCacheLoad and FcDirCacheRead.
Scans the cache directories in config, removing any instances of the cache file for dir. Returns FcFalse when some internal error occurs (out of memory, etc). Errors actually unlinking any files are ignored.
Loads the cache related to dir. If no cache file exists, returns NULL. The name of the cache file is returned in cache_file, unless that is NULL. See also FcDirCacheRead.
This returns a cache for dir. If force is FcFalse, then an existing, valid cache file will be used. Otherwise, a new cache will be created by scanning the directory and that returned.
This function loads a directory cache from cache_file. If file_stat is non-NULL, it will be filled with the results of stat(2) on the cache file.
These routines work with font directory caches, accessing their contents in limited ways. It is not expected that normal applications will need to use these functions.
The returned fontset contains each of the font patterns from cache. This fontset may be modified, but the patterns from the cache are read-only.
The set of subdirectories stored in a cache file are indexed by this function, i should range from 0 to n-1, where n is the return value from FcCacheNumSubdir.
This returns the number of fonts which would be included in the return from FcCacheCopySet.
This tries to clean up the cache directory of cache_dir. This returns FcTrue if the operation is successfully complete. otherwise FcFalse.
A data structure for enumerating strings, used to list directories while scanning the configuration as directories are added while scanning.
Returns whether set_a contains precisely the same strings as set_b. Ordering of strings within the two sets is not considered.
Adds a copy s to set, The copy is created with FcStrCopyFilename so that leading '~' values are replaced with the value of the HOME environment variable.
Fontconfig manipulates many UTF-8 strings represented with the FcChar8 type. These functions are exposed to help applications deal with these UTF-8 strings in a locale-insensitive manner.
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.
Converts the Unicode char from src into dst and returns the number of bytes needed to encode the char.
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.
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.
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.
Allocates memory, copies s and returns the resulting buffer. Yes, this is strdup, but that function isn't available on every platform.
Allocates memory, copies s, converting upper case letters to lower case and returns the allocated buffer.
FcStrCopyFilename constructs an absolute pathname from s. It converts any leading '~' characters in to the value of the HOME environment variable, and any relative paths are converted to absolute paths using the current working directory. Sequences of '/' characters are converted to a single '/', and names containing the current directory '.' or parent directory '..' are correctly reconstructed. Returns NULL if '~' is the leading character and HOME is unset or disabled (see FcConfigEnableHome).
Returns the usual <0, 0, >0 result of comparing s1 and s2. This test is case-insensitive for all proper UTF-8 encoded strings.
Returns the location of s2 in s1. Returns NULL if s2 is not present in s1. This test will operate properly with UTF8 encoded strings.
Returns the location of s2 in s1, ignoring case. Returns NULL if s2 is not present in s1. This test is case-insensitive for all proper UTF-8 encoded strings.
This function allocates new storage and places the concatenation of s1 and s2 there, returning the new string.
This is just a wrapper around free(3) which helps track memory usage of strings within the fontconfig library.
Creates a filename from the given elements of strings as file paths and concatenate them with the appropriate file separator. Arguments must be null-terminated. This returns a newly-allocated memory which should be freed when no longer needed.
Returns the directory containing file. This is returned in newly allocated storage which should be freed when no longer needed.