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6 Copyright © 2003 Keith Packard
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9 documentation for any purpose is hereby granted without fee, provided that
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28 <refentrytitle>fonts-conf</refentrytitle>
29 <manvolnum>5</manvolnum>
32 <refname>fonts.conf</refname>
33 <refpurpose>Font configuration files</refpurpose>
44 <refsect1><title>Description</title>
46 Fontconfig is a library designed to provide system-wide font configuration,
47 customization and application access.
50 <refsect1><title>Functional Overview</title>
52 Fontconfig contains two essential modules, the configuration module which
53 builds an internal configuration from XML files and the matching module
54 which accepts font patterns and returns the nearest matching font.
56 <refsect2><title>Font Configuration</title>
58 The configuration module consists of the FcConfig datatype, libexpat and
59 FcConfigParse which walks over an XML tree and amends a configuration with
60 data found within. From an external perspective, configuration of the
61 library consists of generating a valid XML tree and feeding that to
62 FcConfigParse. The only other mechanism provided to applications for
63 changing the running configuration is to add fonts and directories to the
64 list of application-provided font files.
66 The intent is to make font configurations relatively static, and shared by
67 as many applications as possible. It is hoped that this will lead to more
68 stable font selection when passing names from one application to another.
69 XML was chosen as a configuration file format because it provides a format
70 which is easy for external agents to edit while retaining the correct
73 Font configuration is separate from font matching; applications needing to
74 do their own matching can access the available fonts from the library and
75 perform private matching. The intent is to permit applications to pick and
76 choose appropriate functionality from the library instead of forcing them to
77 choose between this library and a private configuration mechanism. The hope
78 is that this will ensure that configuration of fonts for all applications
79 can be centralized in one place. Centralizing font configuration will
80 simplify and regularize font installation and customization.
84 <title>Font Properties</title>
86 While font patterns may contain essentially any properties, there are some
87 well known properties with associated types. Fontconfig uses some of these
88 properties for font matching and font completion. Others are provided as a
89 convenience for the applications' rendering mechanism.
92 Property Type Description
93 --------------------------------------------------------------
94 family String Font family names
95 familylang String Languages corresponding to each family
96 style String Font style. Overrides weight and slant
97 stylelang String Languages corresponding to each style
98 fullname String Font full names (often includes style)
99 fullnamelang String Languages corresponding to each fullname
100 slant Int Italic, oblique or roman
101 weight Int Light, medium, demibold, bold or black
102 size Double Point size
103 width Int Condensed, normal or expanded
104 aspect Double Stretches glyphs horizontally before hinting
105 pixelsize Double Pixel size
106 spacing Int Proportional, dual-width, monospace or charcell
107 foundry String Font foundry name
108 antialias Bool Whether glyphs can be antialiased
109 hinting Bool Whether the rasterizer should use hinting
110 hintstyle Int Automatic hinting style
111 verticallayout Bool Use vertical layout
112 autohint Bool Use autohinter instead of normal hinter
113 globaladvance Bool Use font global advance data
114 file String The filename holding the font
115 index Int The index of the font within the file
116 ftface FT_Face Use the specified FreeType face object
117 rasterizer String Which rasterizer is in use
118 outline Bool Whether the glyphs are outlines
119 scalable Bool Whether glyphs can be scaled
120 scale Double Scale factor for point->pixel conversions
121 dpi Double Target dots per inch
122 rgba Int unknown, rgb, bgr, vrgb, vbgr,
123 none - subpixel geometry
124 lcdfilter Int Type of LCD filter
125 minspace Bool Eliminate leading from line spacing
126 charset CharSet Unicode chars encoded by the font
127 lang String List of RFC-3066-style languages this
129 fontversion Int Version number of the font
130 capability String List of layout capabilities in the font
131 embolden Bool Rasterizer should synthetically embolden the font
135 <title>Font Matching</title>
137 Fontconfig performs matching by measuring the distance from a provided
138 pattern to all of the available fonts in the system. The closest matching
139 font is selected. This ensures that a font will always be returned, but
140 doesn't ensure that it is anything like the requested pattern.
142 Font matching starts with an application constructed pattern. The desired
143 attributes of the resulting font are collected together in a pattern. Each
144 property of the pattern can contain one or more values; these are listed in
145 priority order; matches earlier in the list are considered "closer" than
146 matches later in the list.
148 The initial pattern is modified by applying the list of editing instructions
149 specific to patterns found in the configuration; each consists of a match
150 predicate and a set of editing operations. They are executed in the order
151 they appeared in the configuration. Each match causes the associated
152 sequence of editing operations to be applied.
154 After the pattern has been edited, a sequence of default substitutions are
155 performed to canonicalize the set of available properties; this avoids the
156 need for the lower layers to constantly provide default values for various
157 font properties during rendering.
159 The canonical font pattern is finally matched against all available fonts.
160 The distance from the pattern to the font is measured for each of several
161 properties: foundry, charset, family, lang, spacing, pixelsize, style,
162 slant, weight, antialias, rasterizer and outline. This list is in priority
163 order -- results of comparing earlier elements of this list weigh more
164 heavily than later elements.
166 There is one special case to this rule; family names are split into two
167 bindings; strong and weak. Strong family names are given greater precedence
168 in the match than lang elements while weak family names are given lower
169 precedence than lang elements. This permits the document language to drive
170 font selection when any document specified font is unavailable.
172 The pattern representing that font is augmented to include any properties
173 found in the pattern but not found in the font itself; this permits the
174 application to pass rendering instructions or any other data through the
175 matching system. Finally, the list of editing instructions specific to
176 fonts found in the configuration are applied to the pattern. This modified
177 pattern is returned to the application.
179 The return value contains sufficient information to locate and rasterize the
180 font, including the file name, pixel size and other rendering data. As
181 none of the information involved pertains to the FreeType library,
182 applications are free to use any rasterization engine or even to take
183 the identified font file and access it directly.
185 The match/edit sequences in the configuration are performed in two passes
186 because there are essentially two different operations necessary -- the
187 first is to modify how fonts are selected; aliasing families and adding
188 suitable defaults. The second is to modify how the selected fonts are
189 rasterized. Those must apply to the selected font, not the original pattern
190 as false matches will often occur.
193 <refsect2><title>Font Names</title>
195 Fontconfig provides a textual representation for patterns that the library
196 can both accept and generate. The representation is in three parts, first a
197 list of family names, second a list of point sizes and finally a list of
198 additional properties:
201 <families>-<point sizes>:<name1>=<values1>:<name2>=<values2>...
204 Values in a list are separated with commas. The name needn't include either
205 families or point sizes; they can be elided. In addition, there are
206 symbolic constants that simultaneously indicate both a name and a value.
207 Here are some examples:
211 ----------------------------------------------------------
212 Times-12 12 point Times Roman
213 Times-12:bold 12 point Times Bold
214 Courier:italic Courier Italic in the default size
215 Monospace:matrix=1 .1 0 1 The users preferred monospace font
216 with artificial obliquing
219 The '\', '-', ':' and ',' characters in family names must be preceeded by a
220 '\' character to avoid having them misinterpreted. Similarly, values
221 containing '\', '=', '_', ':' and ',' must also have them preceeded by a
222 '\' character. The '\' characters are stripped out of the family name and
223 values as the font name is read.
227 <refsect1><title>Debugging Applications</title>
229 To help diagnose font and applications problems, fontconfig is built with a
230 large amount of internal debugging left enabled. It is controlled by means
231 of the FC_DEBUG environment variable. The value of this variable is
232 interpreted as a number, and each bit within that value controls different
237 ---------------------------------------------------------
238 MATCH 1 Brief information about font matching
239 MATCHV 2 Extensive font matching information
240 EDIT 4 Monitor match/test/edit execution
241 FONTSET 8 Track loading of font information at startup
242 CACHE 16 Watch cache files being written
243 CACHEV 32 Extensive cache file writing information
244 PARSE 64 (no longer in use)
245 SCAN 128 Watch font files being scanned to build caches
246 SCANV 256 Verbose font file scanning information
247 MEMORY 512 Monitor fontconfig memory usage
248 CONFIG 1024 Monitor which config files are loaded
249 LANGSET 2048 Dump char sets used to construct lang values
250 OBJTYPES 4096 Display message when value typechecks fail
253 Add the value of the desired debug levels together and assign that (in
254 base 10) to the FC_DEBUG environment variable before running the
255 application. Output from these statements is sent to stdout.
258 <refsect1><title>Lang Tags</title>
260 Each font in the database contains a list of languages it supports. This is
261 computed by comparing the Unicode coverage of the font with the orthography
262 of each language. Languages are tagged using an RFC-3066 compatible naming
263 and occur in two parts -- the ISO 639 language tag followed a hyphen and then
264 by the ISO 3166 country code. The hyphen and country code may be elided.
266 Fontconfig has orthographies for several languages built into the library.
267 No provision has been made for adding new ones aside from rebuilding the
268 library. It currently supports 122 of the 139 languages named in ISO 639-1,
269 141 of the languages with two-letter codes from ISO 639-2 and another 30
270 languages with only three-letter codes. Languages with both two and three
271 letter codes are provided with only the two letter code.
273 For languages used in multiple territories with radically different
274 character sets, fontconfig includes per-territory orthographies. This
275 includes Azerbaijani, Kurdish, Pashto, Tigrinya and Chinese.
278 <refsect1><title>Configuration File Format</title>
280 Configuration files for fontconfig are stored in XML format; this
281 format makes external configuration tools easier to write and ensures that
282 they will generate syntactically correct configuration files. As XML
283 files are plain text, they can also be manipulated by the expert user using
286 The fontconfig document type definition resides in the external entity
287 "fonts.dtd"; this is normally stored in the default font configuration
288 directory (&confdir;). Each configuration file should contain the
291 <?xml version="1.0"?>
292 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
298 <refsect2><title><literal><fontconfig></literal></title><para>
299 This is the top level element for a font configuration and can contain
300 <literal><dir></literal>, <literal><cache></literal>, <literal><include></literal>, <literal><match></literal> and <literal><alias></literal> elements in any order.
302 <refsect2><title><literal><dir></literal></title><para>
303 This element contains a directory name which will be scanned for font files
304 to include in the set of available fonts.
306 <refsect2><title><literal><cache></literal></title><para>
307 This element contains a file name for the per-user cache of font
308 information. If it starts with '~', it refers to a file in the users
309 home directory. This file is used to hold information about fonts that
310 isn't present in the per-directory cache files. It is automatically
311 maintained by the fontconfig library. The default for this file
312 is ``~/.fonts.cache-<literal><version></literal>'', where <literal><version></literal> is the font configuration
313 file version number (currently 2).
315 <refsect2><title><literal><include ignore_missing="no"></literal></title><para>
316 This element contains the name of an additional configuration file or
317 directory. If a directory, every file within that directory starting with an
318 ASCII digit (U+0030 - U+0039) and ending with the string ``.conf'' will be processed in sorted order. When
319 the XML datatype is traversed by FcConfigParse, the contents of the file(s)
320 will also be incorporated into the configuration by passing the filename(s) to
321 FcConfigLoadAndParse. If 'ignore_missing' is set to "yes" instead of the
322 default "no", a missing file or directory will elicit no warning message from
325 <refsect2><title><literal><config></literal></title><para>
326 This element provides a place to consolidate additional configuration
327 information. <literal><config></literal> can contain <literal><blank></literal> and <literal><rescan></literal> elements in any
330 <refsect2><title><literal><blank></literal></title><para>
331 Fonts often include "broken" glyphs which appear in the encoding but are
332 drawn as blanks on the screen. Within the <literal><blank></literal> element, place each
333 Unicode characters which is supposed to be blank in an <literal><int></literal> element.
334 Characters outside of this set which are drawn as blank will be elided from
335 the set of characters supported by the font.
337 <refsect2><title><literal><rescan></literal></title><para>
338 The <literal><rescan></literal> element holds an <literal><int></literal> element which indicates the default
339 interval between automatic checks for font configuration changes.
340 Fontconfig will validate all of the configuration files and directories and
341 automatically rebuild the internal datastructures when this interval passes.
343 <refsect2><title><literal><selectfont></literal></title><para>
344 This element is used to black/white list fonts from being listed or matched
345 against. It holds acceptfont and rejectfont elements.
347 <refsect2><title><literal><acceptfont></literal></title><para>
348 Fonts matched by an acceptfont element are "whitelisted"; such fonts are
349 explicitly included in the set of fonts used to resolve list and match
350 requests; including them in this list protects them from being "blacklisted"
351 by a rejectfont element. Acceptfont elements include glob and pattern
352 elements which are used to match fonts.
354 <refsect2><title><literal><rejectfont></literal></title><para>
355 Fonts matched by an rejectfont element are "blacklisted"; such fonts are
356 excluded from the set of fonts used to resolve list and match requests as if
357 they didn't exist in the system. Rejectfont elements include glob and
358 pattern elements which are used to match fonts.
360 <refsect2><title><literal><glob></literal></title><para>
361 Glob elements hold shell-style filename matching patterns (including ? and
362 *) which match fonts based on their complete pathnames. This can be used to
363 exclude a set of directories (/usr/share/fonts/uglyfont*), or particular
364 font file types (*.pcf.gz), but the latter mechanism relies rather heavily
365 on filenaming conventions which can't be relied upon. Note that globs
366 only apply to directories, not to individual fonts.
368 <refsect2><title><literal><pattern></literal></title><para>
369 Pattern elements perform list-style matching on incoming fonts; that is,
370 they hold a list of elements and associated values. If all of those
371 elements have a matching value, then the pattern matches the font. This can
372 be used to select fonts based on attributes of the font (scalable, bold,
373 etc), which is a more reliable mechanism than using file extensions.
374 Pattern elements include patelt elements.
376 <refsect2><title><literal><patelt name="property"></literal></title><para>
377 Patelt elements hold a single pattern element and list of values. They must
378 have a 'name' attribute which indicates the pattern element name. Patelt
379 elements include int, double, string, matrix, bool, charset and const
382 <refsect2><title><literal><match target="pattern"></literal></title><para>
383 This element holds first a (possibly empty) list of <literal><test></literal> elements and then
384 a (possibly empty) list of <literal><edit></literal> elements. Patterns which match all of the
385 tests are subjected to all the edits. If 'target' is set to "font" instead
386 of the default "pattern", then this element applies to the font name
387 resulting from a match rather than a font pattern to be matched. If 'target'
388 is set to "scan", then this element applies when the font is scanned to
389 build the fontconfig database.
391 <refsect2><title><literal><test qual="any" name="property" target="default" compare="eq"></literal></title><para>
392 This element contains a single value which is compared with the target
393 ('pattern', 'font', 'scan' or 'default') property "property" (substitute any of the property names seen
394 above). 'compare' can be one of "eq", "not_eq", "less", "less_eq", "more", or
395 "more_eq". 'qual' may either be the default, "any", in which case the match
396 succeeds if any value associated with the property matches the test value, or
397 "all", in which case all of the values associated with the property must
398 match the test value. When used in a <match target="font"> element,
399 the target= attribute in the <test> element selects between matching
400 the original pattern or the font. "default" selects whichever target the
401 outer <match> element has selected.
403 <refsect2><title><literal><edit name="property" mode="assign" binding="weak"></literal></title><para>
404 This element contains a list of expression elements (any of the value or
405 operator elements). The expression elements are evaluated at run-time and
406 modify the property "property". The modification depends on whether
407 "property" was matched by one of the associated <literal><test></literal> elements, if so, the
408 modification may affect the first matched value. Any values inserted into
409 the property are given the indicated binding ("strong", "weak" or "same")
410 with "same" binding using the value from the matched pattern element.
413 Mode With Match Without Match
414 ---------------------------------------------------------------------
415 "assign" Replace matching value Replace all values
416 "assign_replace" Replace all values Replace all values
417 "prepend" Insert before matching Insert at head of list
418 "prepend_first" Insert at head of list Insert at head of list
419 "append" Append after matching Append at end of list
420 "append_last" Append at end of list Append at end of list
423 <refsect2><title><literal><int></literal>, <literal><double></literal>, <literal><string></literal>, <literal><bool></literal></title><para>
424 These elements hold a single value of the indicated type. <literal><bool></literal>
425 elements hold either true or false. An important limitation exists in
426 the parsing of floating point numbers -- fontconfig requires that
427 the mantissa start with a digit, not a decimal point, so insert a leading
428 zero for purely fractional values (e.g. use 0.5 instead of .5 and -0.5
431 <refsect2><title><literal><matrix></literal></title><para>
432 This element holds the four <literal><double></literal> elements of an affine
435 <refsect2><title><literal><name></literal></title><para>
436 Holds a property name. Evaluates to the first value from the property of
437 the font, not the pattern.
439 <refsect2><title><literal><const></literal></title><para>
440 Holds the name of a constant; these are always integers and serve as
441 symbolic names for common font values:
443 Constant Property Value
444 -------------------------------------
462 ultracondensed width 50
463 extracondensed width 63
465 semicondensed width 87
467 semiexpanded width 113
469 extraexpanded width 150
470 ultraexpanded width 200
471 proportional spacing 0
482 lcddefault lcdfilter 1
484 lcdlegacy lcdfilter 3
486 hintslight hintstyle 1
487 hintmedium hintstyle 2
493 <title><literal><or></literal>, <literal><and></literal>, <literal><plus></literal>, <literal><minus></literal>, <literal><times></literal>, <literal><divide></literal></title>
495 These elements perform the specified operation on a list of expression
496 elements. <literal><or></literal> and <literal><and></literal> are boolean, not bitwise.
500 <title><literal><eq></literal>, <literal><not_eq></literal>, <literal><less></literal>, <literal><less_eq></literal>, <literal><more></literal>, <literal><more_eq></literal></title>
502 These elements compare two values, producing a boolean result.
504 <refsect2><title><literal><not></literal></title><para>
505 Inverts the boolean sense of its one expression element
507 <refsect2><title><literal><if></literal></title><para>
508 This element takes three expression elements; if the value of the first is
509 true, it produces the value of the second, otherwise it produces the value
512 <refsect2><title><literal><alias></literal></title><para>
513 Alias elements provide a shorthand notation for the set of common match
514 operations needed to substitute one font family for another. They contain a
515 <literal><family></literal> element followed by optional <literal><prefer></literal>, <literal><accept></literal> and <literal><default></literal>
516 elements. Fonts matching the <literal><family></literal> element are edited to prepend the
517 list of <literal><prefer></literal>ed families before the matching <literal><family></literal>, append the
518 <literal><accept></literal>able families after the matching <literal><family></literal> and append the <literal><default></literal>
519 families to the end of the family list.
521 <refsect2><title><literal><family></literal></title><para>
522 Holds a single font family name
524 <refsect2><title><literal><prefer></literal>, <literal><accept></literal>, <literal><default></literal></title><para>
525 These hold a list of <literal><family></literal> elements to be used by the <literal><alias></literal> element.
528 <refsect1><title>EXAMPLE CONFIGURATION FILE</title>
529 <refsect2><title>System configuration file</title>
531 This is an example of a system-wide configuration file
534 <?xml version="1.0"?>
535 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
536 <!-- &confdir;/fonts.conf file to configure system font access -->
539 Find fonts in these directories
541 <dir>/usr/share/fonts</dir>
542 <dir>/usr/X11R6/lib/X11/fonts</dir>
545 Accept deprecated 'mono' alias, replacing it with 'monospace'
547 <match target="pattern">
548 <test qual="any" name="family"><string>mono</string></test>
549 <edit name="family" mode="assign"><string>monospace</string></edit>
553 Names not including any well known alias are given 'sans'
555 <match target="pattern">
556 <test qual="all" name="family" mode="not_eq">sans</test>
557 <test qual="all" name="family" mode="not_eq">serif</test>
558 <test qual="all" name="family" mode="not_eq">monospace</test>
559 <edit name="family" mode="append_last"><string>sans</string></edit>
563 Load per-user customization file, but don't complain
566 <include ignore_missing="yes">~/.fonts.conf</include>
569 Load local customization files, but don't complain
572 <include ignore_missing="yes">conf.d</include>
573 <include ignore_missing="yes">local.conf</include>
576 Alias well known font names to available TrueType fonts.
577 These substitute TrueType faces for similar Type1
578 faces to improve screen appearance.
581 <family>Times</family>
582 <prefer><family>Times New Roman</family></prefer>
583 <default><family>serif</family></default>
586 <family>Helvetica</family>
587 <prefer><family>Arial</family></prefer>
588 <default><family>sans</family></default>
591 <family>Courier</family>
592 <prefer><family>Courier New</family></prefer>
593 <default><family>monospace</family></default>
597 Provide required aliases for standard names
598 Do these after the users configuration file so that
599 any aliases there are used preferentially
602 <family>serif</family>
603 <prefer><family>Times New Roman</family></prefer>
606 <family>sans</family>
607 <prefer><family>Arial</family></prefer>
610 <family>monospace</family>
611 <prefer><family>Andale Mono</family></prefer>
616 <refsect2><title>User configuration file</title>
618 This is an example of a per-user configuration file that lives in
622 <?xml version="1.0"?>
623 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
624 <!-- ~/.fonts.conf for per-user font configuration -->
628 Private font directory
630 <dir>~/.fonts</dir>
633 use rgb sub-pixel ordering to improve glyph appearance on
634 LCD screens. Changes affecting rendering, but not matching
635 should always use target="font".
637 <match target="font">
638 <edit name="rgba" mode="assign"><const>rgb</const></edit>
644 <refsect1><title>Files</title>
646 <emphasis>fonts.conf</emphasis>
647 contains configuration information for the fontconfig library
648 consisting of directories to look at for font information as well as
649 instructions on editing program specified font patterns before attempting to
650 match the available fonts. It is in xml format.
653 <emphasis>conf.d</emphasis>
654 is the conventional name for a directory of additional configuration files
655 managed by external applications or the local administrator. The
656 filenames starting with decimal digits are sorted in lexicographic order
657 and used as additional configuration files. All of these files are in xml
658 format. The master fonts.conf file references this directory in an
659 <include> directive.
662 <emphasis>fonts.dtd</emphasis>
663 is a DTD that describes the format of the configuration files.
666 <emphasis>~/.fonts.conf.d</emphasis>
667 is the conventional name for a per-user directory of (typically
668 auto-generated) configuration files, although the
669 actual location is specified in the global fonts.conf file.
672 <emphasis>~/.fonts.conf</emphasis>
673 is the conventional location for per-user font configuration, although the
674 actual location is specified in the global fonts.conf file.
677 <emphasis> ~/.fonts.cache-*</emphasis>
678 is the conventional repository of font information that isn't found in the
679 per-directory caches. This file is automatically maintained by fontconfig.
682 <refsect1><title>See Also</title>
684 fc-cat(1), fc-cache(1), fc-list(1), fc-match(1), fc-query(1)
687 <refsect1><title>Version</title>
689 Fontconfig version &version;
git.wh0rd.org / fontconfig.git / blob