Provided by: fontconfig-config_2.6.0-1ubuntu12_all bug

NAME

       fonts.conf - Font configuration files

SYNOPSIS

          /etc/fonts/fonts.conf
          /etc/fonts/fonts.dtd
          /etc/fonts/conf.d
          ~/.fonts.conf

DESCRIPTION

       Fontconfig   is   a   library  designed  to  provide  system-wide  font
       configuration, customization and application access.

FUNCTIONAL OVERVIEW

       Fontconfig contains two essential  modules,  the  configuration  module
       which  builds an internal configuration from XML files and the matching
       module which accepts font patterns and  returns  the  nearest  matching
       font.

   FONT CONFIGURATION
       The  configuration  module  consists of the FcConfig datatype, libexpat
       and  FcConfigParse  which  walks  over  an  XML  tree  and   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.

   FONT PROPERTIES
       While font patterns may contain essentially any properties,  there  are
       some well known properties with associated types.  Fontconfig uses some
       of these properties for font matching and font completion.  Others  are
       provided as a convenience for the applications’ rendering mechanism.

         Property        Type    Description
         --------------------------------------------------------------
         family          String  Font family names
         familylang      String  Languages corresponding to each family
         style           String  Font style. Overrides weight and slant
         stylelang       String  Languages corresponding to each style
         fullname        String  Font full names (often includes style)
         fullnamelang    String  Languages corresponding to each fullname
         slant           Int     Italic, oblique or roman
         weight          Int     Light, medium, demibold, bold or black
         size            Double  Point size
         width           Int     Condensed, normal or expanded
         aspect          Double  Stretches glyphs horizontally before hinting
         pixelsize       Double  Pixel size
         spacing         Int     Proportional, dual-width, monospace or charcell
         foundry         String  Font foundry name
         antialias       Bool    Whether glyphs can be antialiased
         hinting         Bool    Whether the rasterizer should use hinting
         hintstyle       Int     Automatic hinting style
         verticallayout  Bool    Use vertical layout
         autohint        Bool    Use autohinter instead of normal hinter
         globaladvance   Bool    Use font global advance data
         file            String  The filename holding the font
         index           Int     The index of the font within the file
         ftface          FT_Face Use the specified FreeType face object
         rasterizer      String  Which rasterizer is in use
         outline         Bool    Whether the glyphs are outlines
         scalable        Bool    Whether glyphs can be scaled
         scale           Double  Scale factor for point->pixel conversions
         dpi             Double  Target dots per inch
         rgba            Int     unknown, rgb, bgr, vrgb, vbgr,
                                 none - subpixel geometry
         lcdfilter       Int     Type of LCD filter
         minspace        Bool    Eliminate leading from line spacing
         charset         CharSet Unicode chars encoded by the font
         lang            String  List of RFC-3066-style languages this
                                 font supports
         fontversion     Int     Version number of the font
         capability      String  List of layout capabilities in the font
         embolden        Bool    Rasterizer should synthetically embolden the font

   FONT MATCHING
       Fontconfig  performs matching by measuring the distance from a provided
       pattern to all of the available  fonts  in  the  system.   The  closest
       matching  font  is  selected.   This ensures that a font will always be
       returned, but doesn’t ensure that it is  anything  like  the  requested
       pattern.

       Font  matching  starts  with  an  application constructed pattern.  The
       desired attributes of the resulting font are collected  together  in  a
       pattern.   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,  family,  lang,  spacing,
       pixelsize, style, slant, weight,  antialias,  rasterizer  and  outline.
       This list is in priority order -- results of comparing earlier elements
       of this list weigh more heavily than later elements.

       There is one special case to this rule; family names are split into two
       bindings;  strong  and  weak.   Strong  family  names are given greater
       precedence in the match than lang elements while weak family names  are
       given  lower  precedence than lang elements.  This permits the document
       language to drive font selection when any document  specified  font  is
       unavailable.

       The  pattern  representing  that  font  is  augmented  to  include  any
       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.

   FONT NAMES
       Fontconfig provides a textual  representation  for  patterns  that  the
       library  can  both accept and generate.  The representation is in three
       parts, first a list of family names, second a list of point  sizes  and
       finally a list of additional properties:

            <families>-<point sizes>:<name1>=<values1>:<name2>=<values2>...

       Values  in  a list are separated with commas.  The name needn’t include
       either families or point sizes; they can be elided.  In addition, there
       are  symbolic  constants that simultaneously indicate both a name and a
       value.  Here are some examples:

         Name                            Meaning
         ----------------------------------------------------------
         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

       The ’\’, ’-’, ’:’ and ’,’ characters in family names must be  preceeded
       by  a  ’\’  character  to  avoid having them misinterpreted. Similarly,
       values containing ’\’, ’=’, ’_’,  ’:’  and  ’,’  must  also  have  them
       preceeded  by  a  ’\’ character. The ’\’ characters are stripped out of
       the family name and values as the font name is read.

DEBUGGING APPLICATIONS

       To help diagnose font and applications problems,  fontconfig  is  built
       with  a  large  amount  of  internal  debugging  left  enabled.  It  is
       controlled by means of the FC_DEBUG environment variable. The value  of
       this  variable  is  interpreted  as  a number, and each bit within that
       value controls different debugging messages.

         Name         Value    Meaning
         ---------------------------------------------------------
         MATCH            1    Brief information about font matching
         MATCHV           2    Extensive font matching information
         EDIT             4    Monitor match/test/edit execution
         FONTSET          8    Track loading of font information at startup
         CACHE           16    Watch cache files being written
         CACHEV          32    Extensive cache file writing information
         PARSE           64    (no longer in use)
         SCAN           128    Watch font files being scanned to build caches
         SCANV          256    Verbose font file scanning information
         MEMORY         512    Monitor fontconfig memory usage
         CONFIG        1024    Monitor which config files are loaded
         LANGSET       2048    Dump char sets used to construct lang values
         OBJTYPES      4096    Display message when value typechecks fail

       Add the value of the desired debug levels together and assign that  (in
       base  10)  to  the  FC_DEBUG  environment  variable  before running the
       application. Output from these statements is sent to stdout.

LANG TAGS

       Each font in the database contains a list  of  languages  it  supports.
       This is computed by comparing the Unicode coverage of the font with the
       orthography of each language.  Languages are tagged using  an  RFC-3066
       compatible  naming  and  occur in two parts -- the ISO 639 language tag
       followed a hyphen and then by the ISO 3166 country  code.   The  hyphen
       and country code may be elided.

       Fontconfig  has  orthographies  for  several  languages  built into the
       library.  No provision has been made for adding  new  ones  aside  from
       rebuilding the library.  It currently supports 122 of the 139 languages
       named in ISO 639-1, 141 of the languages with two-letter codes from ISO
       639-2 and another 30 languages with only three-letter codes.  Languages
       with both two and three letter codes are provided  with  only  the  two
       letter code.

       For  languages  used  in  multiple territories with radically different
       character sets, fontconfig includes per-territory orthographies.   This
       includes Azerbaijani, Kurdish, Pashto, Tigrinya and Chinese.

CONFIGURATION FILE FORMAT

       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>

   <FONTCONFIG>
       This is the top level element for a font configuration and can  contain
       <dir>, <cache>, <include>, <match> and <alias> elements in any order.

   <DIR>
       This  element  contains a directory name which will be scanned for font
       files to include in the set of available fonts.

   <CACHE>
       This element contains a file  name  for  the  per-user  cache  of  font
       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-<version>’’, where <version> is the font configuration
       file version number (currently 2).

   <INCLUDE IGNORE_MISSING= NO">"
       This element contains the name of an additional configuration  file  or
       directory.   If  a directory, every file within that directory starting
       with an ASCII digit (U+0030  -  U+0039)  and  ending  with  the  string
       ‘‘.conf’’  will be processed in sorted order.  When the XML datatype is
       traversed by FcConfigParse, the contents of the file(s)  will  also  be
       incorporated  into  the  configuration  by  passing  the filename(s) to
       FcConfigLoadAndParse.  If ’ignore_missing’ is set to "yes"  instead  of
       the  default  "no",  a missing file or directory will elicit no warning
       message from the library.

   <CONFIG>
       This element provides a place to consolidate  additional  configuration
       information.  <config> can contain <blank> and <rescan> elements in any
       order.

   <BLANK>
       Fonts often include "broken" glyphs which appear in  the  encoding  but
       are  drawn  as blanks on the screen.  Within the <blank> element, place
       each Unicode characters which is supposed  to  be  blank  in  an  <int>
       element.   Characters outside of this set which are drawn as blank will
       be elided from the set of characters supported by the font.

   <RESCAN>
       The <rescan> element holds an <int> element which indicates the default
       interval  between  automatic  checks  for  font  configuration changes.
       Fontconfig will validate all of the configuration files and directories
       and   automatically  rebuild  the  internal  datastructures  when  this
       interval passes.

   <SELECTFONT>
       This element is used to black/white list fonts  from  being  listed  or
       matched against.  It holds acceptfont and rejectfont elements.

   <ACCEPTFONT>
       Fonts  matched  by  an acceptfont element are "whitelisted"; such fonts
       are explicitly included in the set of fonts used to  resolve  list  and
       match  requests;  including  them in this list protects them from being
       "blacklisted" by a rejectfont  element.   Acceptfont  elements  include
       glob and pattern elements which are used to match fonts.

   <REJECTFONT>
       Fonts  matched  by  an rejectfont element are "blacklisted"; such fonts
       are excluded from the set of fonts  used  to  resolve  list  and  match
       requests  as  if  they didn’t exist in the system.  Rejectfont elements
       include glob and pattern elements which are used to match fonts.

   <GLOB>
       Glob elements hold shell-style filename matching patterns (including  ?
       and  *)  which match fonts based on their complete pathnames.  This can
       be used to exclude a set of  directories  (/usr/share/fonts/uglyfont*),
       or  particular  font  file  types  (*.pcf.gz), but the latter mechanism
       relies rather heavily on filenaming conventions which can’t  be  relied
       upon.   Note  that  globs  only apply to directories, not to individual
       fonts.

   <PATTERN>
       Pattern elements perform list-style matching on  incoming  fonts;  that
       is,  they  hold  a  list  of elements and associated values.  If all of
       those elements have a matching value,  then  the  pattern  matches  the
       font.  This can be used to select fonts based on attributes of the font
       (scalable, bold, etc), which is a more reliable  mechanism  than  using
       file extensions.  Pattern elements include patelt elements.

   <PATELT NAME= PROPERTY">"
       Patelt elements hold a single pattern element and list of values.  They
       must have a ’name’ attribute which indicates the pattern element  name.
       Patelt  elements include int, double, string, matrix, bool, charset and
       const elements.

   <MATCH TARGET= PATTERN">"
       This element holds first a (possibly empty) list of <test> elements and
       then  a (possibly empty) list of <edit> elements.  Patterns which match
       all of the tests are subjected to all the edits.  If ’target’ is set to
       "font"  instead  of the default "pattern", then this element applies to
       the font name resulting from a match rather than a font pattern  to  be
       matched.  If  ’target’ is set to "scan", then this element applies when
       the font is scanned to build the fontconfig database.

   <TEST QUAL= ANY" NAME="PROPERTY" TARGET="DEFAULT" COMPARE="EQ">"
       This element contains a single value which is compared with the  target
       (’pattern’,   ’font’,   ’scan’   or   ’default’)   property  "property"
       (substitute any of the property names seen above). ’compare’ can be one
       of "eq", "not_eq", "less", "less_eq", "more", or "more_eq".  ’qual’ may
       either be the default, "any", in which case the match succeeds  if  any
       value associated with the property matches the test value, or "all", in
       which case all of the values associated with the  property  must  match
       the  test  value.   When  used  in a <match target="font"> element, the
       target= attribute in the <test> element selects  between  matching  the
       original  pattern  or the font.  "default" selects whichever target the
       outer <match> element has selected.

   <EDIT NAME= PROPERTY" MODE="ASSIGN" BINDING="WEAK">"
       This element contains a list of expression elements (any of  the  value
       or  operator  elements).  The expression elements are evaluated at run-
       time and modify the property "property".  The modification  depends  on
       whether  "property"  was  matched  by  one  of  the  associated  <test>
       elements, if so, the modification may affect the first  matched  value.
       Any  values  inserted into the property are given the indicated binding
       ("strong", "weak" or "same") with "same" binding using the  value  from
       the matched pattern element.  ’mode’ is one of:

         Mode                    With Match              Without Match
         ---------------------------------------------------------------------
         "assign"                Replace matching value  Replace all values
         "assign_replace"        Replace all values      Replace all values
         "prepend"               Insert before matching  Insert at head of list
         "prepend_first"         Insert at head of list  Insert at head of list
         "append"                Append after matching   Append at end of list
         "append_last"           Append at end of list   Append at end of list

   <INT>, <DOUBLE>, <STRING>, <BOOL>
       These  elements  hold  a  single  value  of the indicated type.  <bool>
       elements hold either true or false.  An important limitation exists  in
       the  parsing  of floating point numbers -- fontconfig requires that the
       mantissa start with a digit, not a decimal point, so insert  a  leading
       zero  for purely fractional values (e.g. use 0.5 instead of .5 and -0.5
       instead of -.5).

   <MATRIX>
       This  element  holds  the  four  <double>   elements   of   an   affine
       transformation.

   <NAME>
       Holds  a property name.  Evaluates to the first value from the property
       of the font, not the pattern.

   <CONST>
       Holds the name of a constant; these are always integers  and  serve  as
       symbolic names for common font values:

         Constant        Property        Value
         -------------------------------------
         thin            weight          0
         extralight      weight          40
         ultralight      weight          40
         light           weight          50
         book            weight          75
         regular         weight          80
         normal          weight          80
         medium          weight          100
         demibold        weight          180
         semibold        weight          180
         bold            weight          200
         extrabold       weight          205
         black           weight          210
         heavy           weight          210
         roman           slant           0
         italic          slant           100
         oblique         slant           110
         ultracondensed  width           50
         extracondensed  width           63
         condensed       width           75
         semicondensed   width           87
         normal          width           100
         semiexpanded    width           113
         expanded        width           125
         extraexpanded   width           150
         ultraexpanded   width           200
         proportional    spacing         0
         dual            spacing         90
         mono            spacing         100
         charcell        spacing         110
         unknown         rgba            0
         rgb             rgba            1
         bgr             rgba            2
         vrgb            rgba            3
         vbgr            rgba            4
         none            rgba            5
         lcdnone         lcdfilter       0
         lcddefault      lcdfilter       1
         lcdlight        lcdfilter       2
         lcdlegacy       lcdfilter       3
         hintnone        hintstyle       0
         hintslight      hintstyle       1
         hintmedium      hintstyle       2
         hintfull        hintstyle       3

   <OR>, <AND>, <PLUS>, <MINUS>, <TIMES>, <DIVIDE>
       These  elements perform the specified operation on a list of expression
       elements.  <or> and <and> are boolean, not bitwise.

   <EQ>, <NOT_EQ>, <LESS>, <LESS_EQ>, <MORE>, <MORE_EQ>
       These elements compare two values, producing a boolean result.

   <NOT>
       Inverts the boolean sense of its one expression element

   <IF>
       This element takes three expression elements; if the value of the first
       is true, it produces the value of the second, otherwise it produces the
       value of the third.

   <ALIAS>
       Alias elements provide a shorthand notation for the set of common match
       operations  needed  to  substitute  one  font family for another.  They
       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 families after the matching <family> and append
       the <default> families to the end of the family list.

   <FAMILY>
       Holds a single font family name

   <PREFER>, <ACCEPT>, <DEFAULT>
       These hold a list of <family>  elements  to  be  used  by  the  <alias>
       element.

EXAMPLE CONFIGURATION FILE

   SYSTEM CONFIGURATION FILE
       This is an example of a system-wide configuration file

       <?xml version="1.0"?>
       <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
       <!-- /etc/fonts/fonts.conf file to configure system font access -->
       <fontconfig>
       <!--
            Find fonts in these directories
       -->
       <dir>/usr/share/fonts</dir>
       <dir>/usr/X11R6/lib/X11/fonts</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>

       <!--
            Load local customization files, but don’t complain
            if there aren’t any
       -->
       <include ignore_missing="yes">conf.d</include>
       <include ignore_missing="yes">local.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>Arial</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>Arial</family></prefer>
       </alias>
       <alias>
            <family>monospace</family>
            <prefer><family>Andale Mono</family></prefer>
       </alias>
       </fontconfig>

   USER CONFIGURATION FILE
       This  is  an  example  of  a  per-user configuration file that lives in
       ~/.fonts.conf

       <?xml version="1.0"?>
       <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
       <!-- ~/.fonts.conf for per-user font configuration -->
       <fontconfig>

       <!--
            Private font directory
       -->
       <dir>~/.fonts</dir>

       <!--
            use rgb sub-pixel ordering to improve glyph appearance on
            LCD screens.  Changes affecting rendering, but not matching
            should always use target="font".
       -->
       <match target="font">
            <edit name="rgba" mode="assign"><const>rgb</const></edit>
       </match>
       </fontconfig>

FILES

       fonts.conf  contains  configuration  information  for  the   fontconfig
       library  consisting  of  directories to look at for font information as
       well as instructions on editing program specified font patterns  before
       attempting to match the available fonts.  It is in xml format.

       conf.d   is  the  conventional  name  for  a  directory  of  additional
       configuration files managed  by  external  applications  or  the  local
       administrator.   The  filenames starting with decimal digits are sorted
       in lexicographic order and used as additional configuration files.  All
       of  these  files  are  in  xml  format.   The  master  fonts.conf  file
       references this directory in an <include> directive.

       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.

SEE ALSO

       fc-cache(1), fc-match(1), fc-list(1)

VERSION

       Fontconfig version 2.6.0

                                  31 May 2008                    FONTS-CONF(5)