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6 Copyright © 2003 Keith Packard
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28 <refentrytitle>fonts-conf</refentrytitle>
29 <manvolnum>5</manvolnum>
32 <refname>fonts.conf</refname>
33 <refpurpose>Font configuration files</refpurpose>
43 <refsect1><title>Description</title>
45 Fontconfig is a library designed to provide system-wide font configuration,
46 customization and application access.
49 <refsect1><title>Functional Overview</title>
51 Fontconfig contains two essential modules, the configuration module which
52 builds an internal configuration from XML files and the matching module
53 which accepts font patterns and returns the nearest matching font.
55 <refsect2><title>Font Configuration</title>
57 The configuration module consists of the FcConfig datatype, libexpat and
58 FcConfigParse which walks over an XML tree and amends a configuration with
59 data found within. From an external perspective, configuration of the
60 library consists of generating a valid XML tree and feeding that to
61 FcConfigParse. The only other mechanism provided to applications for
62 changing the running configuration is to add fonts and directories to the
63 list of application-provided font files.
65 The intent is to make font configurations relatively static, and shared by
66 as many applications as possible. It is hoped that this will lead to more
67 stable font selection when passing names from one application to another.
68 XML was chosen as a configuration file format because it provides a format
69 which is easy for external agents to edit while retaining the correct
72 Font configuration is separate from font matching; applications needing to
73 do their own matching can access the available fonts from the library and
74 perform private matching. The intent is to permit applications to pick and
75 choose appropriate functionality from the library instead of forcing them to
76 choose between this library and a private configuration mechanism. The hope
77 is that this will ensure that configuration of fonts for all applications
78 can be centralized in one place. Centralizing font configuration will
79 simplify and regularize font installation and customization.
83 <title>Font Properties</title>
85 While font patterns may contain essentially any properties, there are some
86 well known properties with associated types. Fontconfig uses some of these
87 properties for font matching and font completion. Others are provided as a
88 convenience for the applications' rendering mechanism.
91 Property Type Description
92 --------------------------------------------------------------
93 family String Font family names
94 familylang String Languages corresponding to each family
95 style String Font style. Overrides weight and slant
96 stylelang String Languages corresponding to each style
97 fullname String Font full names (often includes style)
98 fullnamelang String Languages corresponding to each fullname
99 slant Int Italic, oblique or roman
100 weight Int Light, medium, demibold, bold or black
101 size Double Point size
102 width Int Condensed, normal or expanded
103 aspect Double Stretches glyphs horizontally before hinting
104 pixelsize Double Pixel size
105 spacing Int Proportional, dual-width, monospace or charcell
106 foundry String Font foundry name
107 antialias Bool Whether glyphs can be antialiased
108 hinting Bool Whether the rasterizer should use hinting
109 hintstyle Int Automatic hinting style
110 verticallayout Bool Use vertical layout
111 autohint Bool Use autohinter instead of normal hinter
112 globaladvance Bool Use font global advance data
113 file String The filename holding the font
114 index Int The index of the font within the file
115 ftface FT_Face Use the specified FreeType face object
116 rasterizer String Which rasterizer is in use
117 outline Bool Whether the glyphs are outlines
118 scalable Bool Whether glyphs can be scaled
119 scale Double Scale factor for point->pixel conversions
120 dpi Double Target dots per inch
121 rgba Int unknown, rgb, bgr, vrgb, vbgr,
122 none - subpixel geometry
123 lcdfilter Int Type of LCD filter
124 minspace Bool Eliminate leading from line spacing
125 charset CharSet Unicode chars encoded by the font
126 lang String List of RFC-3066-style languages this
128 fontversion Int Version number of the font
129 capability String List of layout capabilities in the font
130 embolden Bool Rasterizer should synthetically embolden the font
134 <title>Font Matching</title>
136 Fontconfig performs matching by measuring the distance from a provided
137 pattern to all of the available fonts in the system. The closest matching
138 font is selected. This ensures that a font will always be returned, but
139 doesn't ensure that it is anything like the requested pattern.
141 Font matching starts with an application constructed pattern. The desired
142 attributes of the resulting font are collected together in a pattern. Each
143 property of the pattern can contain one or more values; these are listed in
144 priority order; matches earlier in the list are considered "closer" than
145 matches later in the list.
147 The initial pattern is modified by applying the list of editing instructions
148 specific to patterns found in the configuration; each consists of a match
149 predicate and a set of editing operations. They are executed in the order
150 they appeared in the configuration. Each match causes the associated
151 sequence of editing operations to be applied.
153 After the pattern has been edited, a sequence of default substitutions are
154 performed to canonicalize the set of available properties; this avoids the
155 need for the lower layers to constantly provide default values for various
156 font properties during rendering.
158 The canonical font pattern is finally matched against all available fonts.
159 The distance from the pattern to the font is measured for each of several
160 properties: foundry, charset, family, lang, spacing, pixelsize, style,
161 slant, weight, antialias, rasterizer and outline. This list is in priority
162 order -- results of comparing earlier elements of this list weigh more
163 heavily than later elements.
165 There is one special case to this rule; family names are split into two
166 bindings; strong and weak. Strong family names are given greater precedence
167 in the match than lang elements while weak family names are given lower
168 precedence than lang elements. This permits the document language to drive
169 font selection when any document specified font is unavailable.
171 The pattern representing that font is augmented to include any properties
172 found in the pattern but not found in the font itself; this permits the
173 application to pass rendering instructions or any other data through the
174 matching system. Finally, the list of editing instructions specific to
175 fonts found in the configuration are applied to the pattern. This modified
176 pattern is returned to the application.
178 The return value contains sufficient information to locate and rasterize the
179 font, including the file name, pixel size and other rendering data. As
180 none of the information involved pertains to the FreeType library,
181 applications are free to use any rasterization engine or even to take
182 the identified font file and access it directly.
184 The match/edit sequences in the configuration are performed in two passes
185 because there are essentially two different operations necessary -- the
186 first is to modify how fonts are selected; aliasing families and adding
187 suitable defaults. The second is to modify how the selected fonts are
188 rasterized. Those must apply to the selected font, not the original pattern
189 as false matches will often occur.
192 <refsect2><title>Font Names</title>
194 Fontconfig provides a textual representation for patterns that the library
195 can both accept and generate. The representation is in three parts, first a
196 list of family names, second a list of point sizes and finally a list of
197 additional properties:
200 <families>-<point sizes>:<name1>=<values1>:<name2>=<values2>...
203 Values in a list are separated with commas. The name needn't include either
204 families or point sizes; they can be elided. In addition, there are
205 symbolic constants that simultaneously indicate both a name and a value.
206 Here are some examples:
210 ----------------------------------------------------------
211 Times-12 12 point Times Roman
212 Times-12:bold 12 point Times Bold
213 Courier:italic Courier Italic in the default size
214 Monospace:matrix=1 .1 0 1 The users preferred monospace font
215 with artificial obliquing
218 The '\', '-', ':' and ',' characters in family names must be preceeded by a
219 '\' character to avoid having them misinterpreted. Similarly, values
220 containing '\', '=', '_', ':' and ',' must also have them preceeded by a
221 '\' character. The '\' characters are stripped out of the family name and
222 values as the font name is read.
226 <refsect1><title>Debugging Applications</title>
228 To help diagnose font and applications problems, fontconfig is built with a
229 large amount of internal debugging left enabled. It is controlled by means
230 of the FC_DEBUG environment variable. The value of this variable is
231 interpreted as a number, and each bit within that value controls different
236 ---------------------------------------------------------
237 MATCH 1 Brief information about font matching
238 MATCHV 2 Extensive font matching information
239 EDIT 4 Monitor match/test/edit execution
240 FONTSET 8 Track loading of font information at startup
241 CACHE 16 Watch cache files being written
242 CACHEV 32 Extensive cache file writing information
243 PARSE 64 (no longer in use)
244 SCAN 128 Watch font files being scanned to build caches
245 SCANV 256 Verbose font file scanning information
246 MEMORY 512 Monitor fontconfig memory usage
247 CONFIG 1024 Monitor which config files are loaded
248 LANGSET 2048 Dump char sets used to construct lang values
249 OBJTYPES 4096 Display message when value typechecks fail
252 Add the value of the desired debug levels together and assign that (in
253 base 10) to the FC_DEBUG environment variable before running the
254 application. Output from these statements is sent to stdout.
257 <refsect1><title>Lang Tags</title>
259 Each font in the database contains a list of languages it supports. This is
260 computed by comparing the Unicode coverage of the font with the orthography
261 of each language. Languages are tagged using an RFC-3066 compatible naming
262 and occur in two parts -- the ISO 639 language tag followed a hyphen and then
263 by the ISO 3166 country code. The hyphen and country code may be elided.
265 Fontconfig has orthographies for several languages built into the library.
266 No provision has been made for adding new ones aside from rebuilding the
267 library. It currently supports 122 of the 139 languages named in ISO 639-1,
268 141 of the languages with two-letter codes from ISO 639-2 and another 30
269 languages with only three-letter codes. Languages with both two and three
270 letter codes are provided with only the two letter code.
272 For languages used in multiple territories with radically different
273 character sets, fontconfig includes per-territory orthographies. This
274 includes Azerbaijani, Kurdish, Pashto, Tigrinya and Chinese.
277 <refsect1><title>Configuration File Format</title>
279 Configuration files for fontconfig are stored in XML format; this
280 format makes external configuration tools easier to write and ensures that
281 they will generate syntactically correct configuration files. As XML
282 files are plain text, they can also be manipulated by the expert user using
285 The fontconfig document type definition resides in the external entity
286 "fonts.dtd"; this is normally stored in the default font configuration
287 directory (&confdir;). Each configuration file should contain the
290 <?xml version="1.0"?>
291 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
297 <refsect2><title><literal><fontconfig></literal></title><para>
298 This is the top level element for a font configuration and can contain
299 <literal><dir></literal>, <literal><cache></literal>, <literal><include></literal>, <literal><match></literal> and <literal><alias></literal> elements in any order.
301 <refsect2><title><literal><dir></literal></title><para>
302 This element contains a directory name which will be scanned for font files
303 to include in the set of available fonts.
305 <refsect2><title><literal><cache></literal></title><para>
306 This element contains a file name for the per-user cache of font
307 information. If it starts with '~', it refers to a file in the users
308 home directory. This file is used to hold information about fonts that
309 isn't present in the per-directory cache files. It is automatically
310 maintained by the fontconfig library. The default for this file
311 is ``~/.fonts.cache-<literal><version></literal>'', where <literal><version></literal> is the font configuration
312 file version number (currently 2).
314 <refsect2><title><literal><include ignore_missing="no"></literal></title><para>
315 This element contains the name of an additional configuration file or
316 directory. If a directory, every file within that directory starting with an
317 ASCII digit (U+0030 - U+0039) and ending with the string ``.conf'' will be processed in sorted order. When
318 the XML datatype is traversed by FcConfigParse, the contents of the file(s)
319 will also be incorporated into the configuration by passing the filename(s) to
320 FcConfigLoadAndParse. If 'ignore_missing' is set to "yes" instead of the
321 default "no", a missing file or directory will elicit no warning message from
324 <refsect2><title><literal><config></literal></title><para>
325 This element provides a place to consolidate additional configuration
326 information. <literal><config></literal> can contain <literal><blank></literal> and <literal><rescan></literal> elements in any
329 <refsect2><title><literal><blank></literal></title><para>
330 Fonts often include "broken" glyphs which appear in the encoding but are
331 drawn as blanks on the screen. Within the <literal><blank></literal> element, place each
332 Unicode characters which is supposed to be blank in an <literal><int></literal> element.
333 Characters outside of this set which are drawn as blank will be elided from
334 the set of characters supported by the font.
336 <refsect2><title><literal><rescan></literal></title><para>
337 The <literal><rescan></literal> element holds an <literal><int></literal> element which indicates the default
338 interval between automatic checks for font configuration changes.
339 Fontconfig will validate all of the configuration files and directories and
340 automatically rebuild the internal datastructures when this interval passes.
342 <refsect2><title><literal><selectfont></literal></title><para>
343 This element is used to black/white list fonts from being listed or matched
344 against. It holds acceptfont and rejectfont elements.
346 <refsect2><title><literal><acceptfont></literal></title><para>
347 Fonts matched by an acceptfont element are "whitelisted"; such fonts are
348 explicitly included in the set of fonts used to resolve list and match
349 requests; including them in this list protects them from being "blacklisted"
350 by a rejectfont element. Acceptfont elements include glob and pattern
351 elements which are used to match fonts.
353 <refsect2><title><literal><rejectfont></literal></title><para>
354 Fonts matched by an rejectfont element are "blacklisted"; such fonts are
355 excluded from the set of fonts used to resolve list and match requests as if
356 they didn't exist in the system. Rejectfont elements include glob and
357 pattern elements which are used to match fonts.
359 <refsect2><title><literal><glob></literal></title><para>
360 Glob elements hold shell-style filename matching patterns (including ? and
361 *) which match fonts based on their complete pathnames. This can be used to
362 exclude a set of directories (/usr/share/fonts/uglyfont*), or particular
363 font file types (*.pcf.gz), but the latter mechanism relies rather heavily
364 on filenaming conventions which can't be relied upon. Note that globs
365 only apply to directories, not to individual fonts.
367 <refsect2><title><literal><pattern></literal></title><para>
368 Pattern elements perform list-style matching on incoming fonts; that is,
369 they hold a list of elements and associated values. If all of those
370 elements have a matching value, then the pattern matches the font. This can
371 be used to select fonts based on attributes of the font (scalable, bold,
372 etc), which is a more reliable mechanism than using file extensions.
373 Pattern elements include patelt elements.
375 <refsect2><title><literal><patelt name="property"></literal></title><para>
376 Patelt elements hold a single pattern element and list of values. They must
377 have a 'name' attribute which indicates the pattern element name. Patelt
378 elements include int, double, string, matrix, bool, charset and const
381 <refsect2><title><literal><match target="pattern"></literal></title><para>
382 This element holds first a (possibly empty) list of <literal><test></literal> elements and then
383 a (possibly empty) list of <literal><edit></literal> elements. Patterns which match all of the
384 tests are subjected to all the edits. If 'target' is set to "font" instead
385 of the default "pattern", then this element applies to the font name
386 resulting from a match rather than a font pattern to be matched. If 'target'
387 is set to "scan", then this element applies when the font is scanned to
388 build the fontconfig database.
390 <refsect2><title><literal><test qual="any" name="property" target="default" compare="eq"></literal></title><para>
391 This element contains a single value which is compared with the target
392 ('pattern', 'font', 'scan' or 'default') property "property" (substitute any of the property names seen
393 above). 'compare' can be one of "eq", "not_eq", "less", "less_eq", "more", or
394 "more_eq". 'qual' may either be the default, "any", in which case the match
395 succeeds if any value associated with the property matches the test value, or
396 "all", in which case all of the values associated with the property must
397 match the test value. When used in a <match target="font"> element,
398 the target= attribute in the <test> element selects between matching
399 the original pattern or the font. "default" selects whichever target the
400 outer <match> element has selected.
402 <refsect2><title><literal><edit name="property" mode="assign" binding="weak"></literal></title><para>
403 This element contains a list of expression elements (any of the value or
404 operator elements). The expression elements are evaluated at run-time and
405 modify the property "property". The modification depends on whether
406 "property" was matched by one of the associated <literal><test></literal> elements, if so, the
407 modification may affect the first matched value. Any values inserted into
408 the property are given the indicated binding ("strong", "weak" or "same")
409 with "same" binding using the value from the matched pattern element.
412 Mode With Match Without Match
413 ---------------------------------------------------------------------
414 "assign" Replace matching value Replace all values
415 "assign_replace" Replace all values Replace all values
416 "prepend" Insert before matching Insert at head of list
417 "prepend_first" Insert at head of list Insert at head of list
418 "append" Append after matching Append at end of list
419 "append_last" Append at end of list Append at end of list
422 <refsect2><title><literal><int></literal>, <literal><double></literal>, <literal><string></literal>, <literal><bool></literal></title><para>
423 These elements hold a single value of the indicated type. <literal><bool></literal>
424 elements hold either true or false. An important limitation exists in
425 the parsing of floating point numbers -- fontconfig requires that
426 the mantissa start with a digit, not a decimal point, so insert a leading
427 zero for purely fractional values (e.g. use 0.5 instead of .5 and -0.5
430 <refsect2><title><literal><matrix></literal></title><para>
431 This element holds the four <literal><double></literal> elements of an affine
434 <refsect2><title><literal><name></literal></title><para>
435 Holds a property name. Evaluates to the first value from the property of
436 the font, not the pattern.
438 <refsect2><title><literal><const></literal></title><para>
439 Holds the name of a constant; these are always integers and serve as
440 symbolic names for common font values:
442 Constant Property Value
443 -------------------------------------
461 ultracondensed width 50
462 extracondensed width 63
464 semicondensed width 87
466 semiexpanded width 113
468 extraexpanded width 150
469 ultraexpanded width 200
470 proportional spacing 0
481 lcddefault lcdfilter 1
483 lcdlegacy lcdfilter 3
485 hintslight hintstyle 1
486 hintmedium hintstyle 2
492 <title><literal><or></literal>, <literal><and></literal>, <literal><plus></literal>, <literal><minus></literal>, <literal><times></literal>, <literal><divide></literal></title>
494 These elements perform the specified operation on a list of expression
495 elements. <literal><or></literal> and <literal><and></literal> are boolean, not bitwise.
499 <title><literal><eq></literal>, <literal><not_eq></literal>, <literal><less></literal>, <literal><less_eq></literal>, <literal><more></literal>, <literal><more_eq></literal></title>
501 These elements compare two values, producing a boolean result.
503 <refsect2><title><literal><not></literal></title><para>
504 Inverts the boolean sense of its one expression element
506 <refsect2><title><literal><if></literal></title><para>
507 This element takes three expression elements; if the value of the first is
508 true, it produces the value of the second, otherwise it produces the value
511 <refsect2><title><literal><alias></literal></title><para>
512 Alias elements provide a shorthand notation for the set of common match
513 operations needed to substitute one font family for another. They contain a
514 <literal><family></literal> element followed by optional <literal><prefer></literal>, <literal><accept></literal> and <literal><default></literal>
515 elements. Fonts matching the <literal><family></literal> element are edited to prepend the
516 list of <literal><prefer></literal>ed families before the matching <literal><family></literal>, append the
517 <literal><accept></literal>able families after the matching <literal><family></literal> and append the <literal><default></literal>
518 families to the end of the family list.
520 <refsect2><title><literal><family></literal></title><para>
521 Holds a single font family name
523 <refsect2><title><literal><prefer></literal>, <literal><accept></literal>, <literal><default></literal></title><para>
524 These hold a list of <literal><family></literal> elements to be used by the <literal><alias></literal> element.
527 <refsect1><title>EXAMPLE CONFIGURATION FILE</title>
528 <refsect2><title>System configuration file</title>
530 This is an example of a system-wide configuration file
533 <?xml version="1.0"?>
534 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
535 <!-- &confdir;/fonts.conf file to configure system font access -->
538 Find fonts in these directories
540 <dir>/usr/share/fonts</dir>
541 <dir>/usr/X11R6/lib/X11/fonts</dir>
544 Accept deprecated 'mono' alias, replacing it with 'monospace'
546 <match target="pattern">
547 <test qual="any" name="family"><string>mono</string></test>
548 <edit name="family" mode="assign"><string>monospace</string></edit>
552 Names not including any well known alias are given 'sans'
554 <match target="pattern">
555 <test qual="all" name="family" mode="not_eq">sans</test>
556 <test qual="all" name="family" mode="not_eq">serif</test>
557 <test qual="all" name="family" mode="not_eq">monospace</test>
558 <edit name="family" mode="append_last"><string>sans</string></edit>
562 Load per-user customization file, but don't complain
565 <include ignore_missing="yes">~/.fonts.conf</include>
568 Load local customization files, but don't complain
571 <include ignore_missing="yes">conf.d</include>
572 <include ignore_missing="yes">local.conf</include>
575 Alias well known font names to available TrueType fonts.
576 These substitute TrueType faces for similar Type1
577 faces to improve screen appearance.
580 <family>Times</family>
581 <prefer><family>Times New Roman</family></prefer>
582 <default><family>serif</family></default>
585 <family>Helvetica</family>
586 <prefer><family>Arial</family></prefer>
587 <default><family>sans</family></default>
590 <family>Courier</family>
591 <prefer><family>Courier New</family></prefer>
592 <default><family>monospace</family></default>
596 Provide required aliases for standard names
597 Do these after the users configuration file so that
598 any aliases there are used preferentially
601 <family>serif</family>
602 <prefer><family>Times New Roman</family></prefer>
605 <family>sans</family>
606 <prefer><family>Arial</family></prefer>
609 <family>monospace</family>
610 <prefer><family>Andale Mono</family></prefer>
615 <refsect2><title>User configuration file</title>
617 This is an example of a per-user configuration file that lives in
621 <?xml version="1.0"?>
622 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
623 <!-- ~/.fonts.conf for per-user font configuration -->
627 Private font directory
629 <dir>~/.fonts</dir>
632 use rgb sub-pixel ordering to improve glyph appearance on
633 LCD screens. Changes affecting rendering, but not matching
634 should always use target="font".
636 <match target="font">
637 <edit name="rgba" mode="assign"><const>rgb</const></edit>
643 <refsect1><title>Files</title>
645 <emphasis>fonts.conf</emphasis>
646 contains configuration information for the fontconfig library
647 consisting of directories to look at for font information as well as
648 instructions on editing program specified font patterns before attempting to
649 match the available fonts. It is in xml format.
652 <emphasis>conf.d</emphasis>
653 is the conventional name for a directory of additional configuration files
654 managed by external applications or the local administrator. The
655 filenames starting with decimal digits are sorted in lexicographic order
656 and used as additional configuration files. All of these files are in xml
657 format. The master fonts.conf file references this directory in an
658 <include> directive.
661 <emphasis>fonts.dtd</emphasis>
662 is a DTD that describes the format of the configuration files.
665 <emphasis>~/.fonts.conf</emphasis>
666 is the conventional location for per-user font configuration, although the
667 actual location is specified in the global fonts.conf file.
670 <emphasis> ~/.fonts.cache-*</emphasis>
671 is the conventional repository of font information that isn't found in the
672 per-directory caches. This file is automatically maintained by fontconfig.
675 <refsect1><title>See Also</title>
677 fc-cat(1), fc-cache(1), fc-list(1), fc-match(1), fc-query(1)
680 <refsect1><title>Version</title>
682 Fontconfig version &version;
git.wh0rd.org / fontconfig.git / blob