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FcPatternFormat(3)					    FcPatternFormat(3)

NAME
       FcPatternFormat	- Format a pattern into	a string according to a	format
       specifier

SYNOPSIS
       #include	<fontconfig/fontconfig.h>

       FcChar8 * FcPatternFormat (FcPattern *pat, const	FcChar8	*format);

DESCRIPTION
       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 charac-
       ters (not "%"), which are copied	unchanged to the  output  stream;  and
       tags  which are interpreted to construct	text from the pattern in a va-
       riety of	ways (explained	below).	 Special characters can	be escaped us-
       ing  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 vari-
       ous 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 pat-
       tern, ":" 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  con-
       tents 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 con-
       tents 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 en-
       closed 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  pat-
       tern 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 en-
       closed  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-expres-
       sion  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 en-
       closed  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}  (%{family-
       lang})\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:

       unparse
	      Expands to the result of calling FcNameUnparse() on the pattern.

       fcmatch
	      Expands to the output of the default output format  of  the  fc-
	      match command on the pattern, without the	final newline.

       fclist Expands  to  the	output of the default output format of the fc-
	      list command on the pattern, without the final newline.

       fccat  Expands to the output of the default output format of the	fc-cat
	      command on the pattern, without the final	newline.

       pkgkit Expands  to  the list of PackageKit font() tags for the pattern.
	      Currently	this includes tags for each family name, and each lan-
	      guage  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.

       For  example,  the format "%{+family,style{%{=unparse}}}\n" will	expand
       to an unparsed name containing only the family and style	element	values
       from pattern.

       The  contents  of any tag can be	followed by a set of zero or more con-
       verters.	A converter is specified by the	character "|" followed by  the
       converter name and arguments. The following converters are defined:

       basename
	      Replaces text with the results of	calling	FcStrBasename()	on it.

       dirname
	      Replaces text with the results of	calling	FcStrDirname() on it.

       downcase
	      Replaces text with the results of	calling	FcStrDowncase()	on it.

       shescape
	      Escapes text for one level of shell expansion.  (Escapes single-
	      quotes, also encloses text in single-quotes.)

       cescape
	      Escapes text such	that it	can be used as part of a C string lit-
	      eral.  (Escapes backslash	and double-quotes.)

       xmlescape
	      Escapes text such	that it	can be used in XML and HTML.  (Escapes
	      less-than, greater-than, and ampersand.)

       delete(chars)
	      Deletes all occurrences of each of the characters	in chars  from
	      the text.	 FIXME:	This converter is not UTF-8 aware yet.

       escape(chars)
	      Escapes  all  occurrences	 of each of the	characters in chars by
	      prepending it by the first character in chars.  FIXME: This con-
	      verter is	not UTF-8 aware	yet.

       translate(from,to)
	      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.

       For example, the	format "%{family|downcase|delete( )}\n"	will expand to
       the values of the family	element	in pattern, lower-cased	and with  spa-
       ces removed.

SINCE
       version 2.9.0

Fontconfig 2.13.92		  09 8ae 2019		    FcPatternFormat(3)

NAME | SYNOPSIS | DESCRIPTION | SINCE

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