Table of Contents
This document describes the support for fonts in X11R7.6. Installing fonts is aimed at the casual user wishing to install fonts in X11R7.6 the rest of the document describes the font support in more detail.
We assume some familiarity with digital fonts. If anything is not clear to you, please consult Appendix: Background at the end of this document for background information.
X11 includes two font systems: the original core X11 fonts system, which is present in all implementations of X11, and the Xft fonts system, which may not yet be distributed with implementations of X11 that are not based on either XFree86 or X11R6.8 or later.
The core X11 fonts system is directly derived from the fonts system included with X11R1 in 1987, which could only use monochrome bitmap fonts. Over the years, it has been more or less happily coerced into dealing with scalable fonts and rotated glyphs.
Xft was designed from the start to provide good support for scalable fonts, and to do so efficiently. Unlike the core fonts system, it supports features such as anti-aliasing and sub-pixel rasterisation. Perhaps more importantly, it gives applications full control over the way glyphs are rendered, making fine typesetting and WYSIWIG display possible. Finally, it allows applications to use fonts that are not installed system-wide for displaying documents with embedded fonts.
Xft is not compatible with the core fonts system: usage of Xft requires fairly extensive changes to toolkits (user-interface libraries). While X.Org will continue to maintain the core fonts system, toolkit authors are encouraged to switch to Xft as soon as possible.
This section explains how to configure both Xft and the core fonts system to access newly-installed fonts.
Xft has no configuration mechanism itself, it relies upon the fontconfig library to configure and customise fonts. That library is not specific to the X Window system, and does not rely on any particular font output mechanism.
Fontconfig looks for fonts in a set of well-known directories that
include all of X11R7.6's standard font directories
/usr/share/fonts/X11/*') by default) as well as a
directory called `
.fonts/' in the user's home directory.
Installing a font for use by Xft applications is as simple
as copying a font file into one of these directories.
$ cp lucbr.ttf ~/.fonts/
Fontconfig will notice the new font at the next opportunity and rebuild its list of fonts. If you want to trigger this update from the command line, you may run the command `fc-cache'.
In order to globally update the system-wide Fontconfig information on Unix systems, you will typically need to run this command as root:
$ su -c fc-cache
Fontconfig's behaviour is controlled by a set of configuration
files: a standard configuration file, `
a host-specific configuration file, `
and a user-specific file called `
.fonts.conf' in the user's
home directory (this can be overridden with the
FONTCONFIG_FILE' environment variable).
Every Fontconfig configuration file must start with the following boilerplate:
<?xml version="1.0"?> <!DOCTYPE fontconfig SYSTEM "fonts.dtd"> <fontconfig>
In addition, every Fontconfig configuration file must end with the following line:
The default Fontconfig configuration file includes the directory
˜/.fonts/' in the list of directories searched for font
files, and this is where user-specific font files should be installed.
In the unlikely case that a new font directory needs to be added, this
can be done with the following syntax:
Another useful option is the ability to disable anti-aliasing (font smoothing) for selected fonts. This can be done with the following syntax:
<match target="font"> <test qual="any" name="family"> <string>Lucida Console</string> </test> <edit name="antialias" mode="assign"> <bool>false</bool> </edit> </match>
Anti-aliasing can be disabled for all fonts by the following incantation:
<match target="font"> <edit name="antialias" mode="assign"> <bool>false</bool> </edit> </match>
Xft supports sub-pixel rasterisation on LCD displays. X11R7.6 should automatically enable this feature on laptops and when using an LCD monitor connected with a DVI cable; you can check whether this was done by typing
$ xdpyinfo -ext RENDER | grep sub-pixel
If this doesn't print anything, you will need to configure Render for your particular LCD hardware manually; this is done with the following syntax:
<match target="font"> <edit name="rgba" mode="assign"> <const>rgb</const> </edit> </match>
The string `
rgb' within the
specifies the order of pixel components on your display, and should be
changed to match your hardware; it can be one of `
LCD screen), `
bgr' (backwards LCD screen), `
screen rotated clockwise) or `
vbgr' (LCD screen rotated
A growing number of applications use Xft in preference to the core fonts system. Some applications, however, need to be explicitly configured to use Xft.
A case in point is XTerm, which can be set to use Xft by using the
-fa' command line option or by setting the `
$ xterm -fa "Courier"
For KDE applications, you should select “Anti-alias fonts” in the “Fonts” panel of KDE's “Control Center”. Note that this option is misnamed: it switches KDE to using Xft but doesn't enable anti-aliasing in case it was disabled by your Xft configuration file.
Gnome applications and Mozilla Firefox will use Xft by default.
Installing fonts in the core system is a two step process. First, you need to create a font directory that contains all the relevant font files as well as some index files. You then need to inform the X server of the existence of this new directory by including it in the font path.
The X11R7.6 server can use bitmap fonts in both the cross-platform BDF format and the somewhat more efficient binary PCF format. (X11R7.6 also supports the obsolete SNF format.)
Bitmap fonts are normally distributed in the BDF format. Before installing such fonts, it is desirable (but not absolutely necessary) to convert the font files to the PCF format. This is done by using the command `bdftopcf', e.g.
$ bdftopcf courier12.bdf
You will then want to compress the resulting PCF font files:
$ gzip courier12.pcf
After the fonts have been converted, you should copy all the font
files that you wish to make available into a arbitrary directory, say
/usr/local/share/fonts/bitmap/'. You should then create the
index file `
fonts.dir' by running the command `mkfontdir'
(please see the mkfontdir(1)
manual page for more information):
$ mkdir /usr/local/share/fonts/bitmap/ $ cp *.pcf.gz /usr/local/share/fonts/bitmap/ $ mkfontdir /usr/local/share/fonts/bitmap/
All that remains is to tell the X server about the existence of the new font directory; see Setting the server font path below.
The X11R7.6 server supports scalable fonts in multiple formats, including Type 1, TrueType, and OpenType/CFF. (Earlier versions of X11 also included support for the Speedo and CID scalable font formats, but that is not included in current releases.)
Installing scalable fonts is very similar to installing bitmap fonts:
you create a directory with the font files, and run `mkfontdir'
to create an index file called `
There is, however, a big difference: `mkfontdir' cannot
automatically recognise scalable font files. For that reason, you
must first index all the font files in a file called
fonts.scale'. While this can be done by hand, it is best done
by using the `mkfontscale' utility.
$ mkfontscale /usr/local/share/fonts/Type1/ $ mkfontdir /usr/local/share/fonts/Type1/
Under some circumstances, it may be necessary to modify the
fonts.scale' file generated by mkfontscale; for more
information, please see the mkfontdir(1) and mkfontscale(1) manual pages and Core fonts and internationalisation
later in this document.
The CID-keyed font format was designed by Adobe Systems for fonts with large character sets. The CID-keyed format is obsolete, as it has been superseded by other formats such as OpenType/CFF and support for CID-keyed fonts has been removed from X11.
The list of directories where the server looks for fonts is known as the font path. Informing the server of the existence of a new font directory consists of putting it on the font path.
The font path is an ordered list; if a client's request matches multiple fonts, the first one in the font path is the one that gets used. When matching fonts, the server makes two passes over the font path: during the first pass, it searches for an exact match; during the second, it searches for fonts suitable for scaling.
For best results, scalable fonts should appear in the font path before
the bitmap fonts; this way, the server will prefer bitmap fonts to
scalable fonts when an exact match is possible, but will avoid scaling
bitmap fonts when a scalable font can be used. (The `
hack, while still supported, should no longer be necessary in X11R7.6.)
You may check the font path of the running server by typing the command
$ xset q
You can specify a special kind of font path directory in the form
The directory specified after the
prefix will be scanned for symlinks and each symlink destination will be
added as a local font path entry.
The symlink can be suffixed by attributes such as
unscaled', which will be passed through
to the underlying font path entry. The only exception is the newly
pri' attribute, which will be
used for ordering the font paths specified by the symlinks.
An example configuration:
75dpi:unscaled:pri=20 -> /usr/share/X11/fonts/75dpi ghostscript:pri=60 -> /usr/share/fonts/default/ghostscript misc:unscaled:pri=10 -> /usr/share/X11/fonts/misc type1:pri=40 -> /usr/share/X11/fonts/Type1 type1:pri=50 -> /usr/share/fonts/default/Type1
This will add
/usr/share/X11/fonts/misc as the
first font path entry with the attribute
unscaled. This is functionally equivalent to
setting the following font path:
/usr/share/X11/fonts/misc:unscaled, /usr/share/X11/fonts/75dpi:unscaled, /usr/share/X11/fonts/Type1, /usr/share/fonts/default/Type1, /usr/share/fonts/default/ghostscript
The `xset' utility may be used to modify the font path for the current session. The font path is set with the command xset fp; a new element is added to the front with xset +fp, and added to the end with xset fp+. For example,
$ xset +fp /usr/local/fonts/Type1 $ xset fp+ /usr/local/fonts/bitmap
Conversely, an element may be removed from the front of the font path with `xset -fp', and removed from the end with `xset fp-'. You may reset the font path to its default value with `xset fp default'.
For more information, please consult the xset(1) manual page.
The default font path (the one used just after server startup or
after `xset fp default') may be specified in the
xorg.conf' file. It is computed by appending all the
directories mentioned in the `
FontPath' entries of the
Files' section in the order in which they appear. If no font path is specified in a config file, the server uses a default
value specified when it was built.
FontPath "/usr/local/fonts/Type1" ... FontPath "/usr/local/fonts/bitmap"
For more information, please consult the xorg.conf(5) manual page.
If you seem to be unable to use some of the fonts you have
installed, the first thing to check is that the `
are correct and that they are readable by the server (the X server
usually runs as root, beware of NFS-mounted font directories). If
this doesn't help, it is quite possible that you are trying to use a
font in a format that is not supported by your server.
X11R7.6 supports the BDF, PCF, SNF, Type 1, TrueType, and OpenType font formats. However, not all X11R7.6 servers come with all the font backends configured in.
On most platforms, the X11R7.6 servers no longer uses font backends from modules that are loaded at runtime. The built in font support corresponds to the functionality formerly provided by these modules:
bitmap fonts (`
TrueType fonts (`
OpenType fonts (`
Type 1 fonts (`
The Sample Implementation of X11 (SI) comes with a large number of
bitmap fonts, including the `
fixed' family, and bitmap versions
of Courier, Times, Helvetica and some members of the Lucida family.
In X11R7.6, a number of these fonts are provided in Unicode-encoded font files now. At build time, these fonts are split into font files encoded according to legacy encodings, a process which allows us to provide the standard fonts in a number of regional encodings with no duplication of work.
For example, the font file
is a Unicode-encoded version of the standard `
fixed' font with
added support for the Latin, Greek, Cyrillic, Georgian, Armenian, IPA
and other scripts plus numerous technical symbols. It contains over
2800 glyphs, covering all characters of ISO 8859 parts 1-5,
7-10, 13-15, as well as all European IBM and Microsoft code pages,
KOI8, WGL4, and the repertoires of many other character sets.
This font is used at build time for generating the font files
6x13-ISO8859-1.bdf 6x13-ISO8859-2.bdf ... 6x13-ISO8859-15.bdf 6x13-KOI8-R.bdf
with respective XLFDs
-misc-fixed-medium-r-normal--13-120-75-75-c-60-iso8859-1 ... -misc-fixed-medium-r-normal--13-120-75-75-c-60-iso8859-15 -misc-fixed-medium-r-normal--13-120-75-75-c-60-koi8-r
The standard short name `
fixed' is normally an alias for
The ClearlyU family of fonts provides a set of 12 pt, 100 dpi proportional fonts with many of the glyphs needed for Unicode text. Together, the fonts contain approximately 7500 glyphs.
The main ClearlyU font has the XLFD
and resides in the font file
Additional ClearlyU fonts include
-mutt-clearlyu alternate glyphs-medium-r-normal--17-120-100-100-p-91-iso10646-1 -mutt-clearlyu pua-medium-r-normal--17-120-100-100-p-111-iso10646-1 -mutt-clearlyu arabic extra-medium-r-normal--17-120-100-100-p-103-fontspecific-0 -mutt-clearlyu ligature-medium-r-normal--17-120-100-100-p-141-fontspecific-0
The Alternate Glyphs font contains additional glyph shapes that are needed for certain languages. A second alternate glyph font will be provided later for cases where a character has more than one commonly used alternate shape (e.g. the Urdu heh).
The PUA font contains extra glyphs that are useful for certain rendering purposes.
The Arabic Extra font contains the glyphs necessary for characters that don't have all of their possible shapes encoded in ISO 10646. The glyphs are roughly ordered according to the order of the characters in the ISO 10646 standard.
The Ligature font contains ligatures for various scripts that may be useful for improved presentation of text.
X11R7.6 includes all the scalable fonts distributed with X11R6.
The IBM Courier set of fonts cover ISO 8859-1 and ISO 8859-2 as well as Adobe Standard Encoding. These fonts have XLFD
and reside in the font files
The Adobe Utopia set of fonts only cover ISO 8859-1 as well as Adobe Standard Encoding. These fonts have XLFD
and reside in the font files
Finally, X11R7.6 also comes with Type 1 versions of Bitstream Courier and Charter. These fonts have XLFD
and reside in the font files
X11R7.6 includes the Luxi family of scalable fonts, in both TrueType and Type 1 format. This family consists of the fonts Luxi Serif, with XLFD
Luxi Sans, with XLFD
and Luxi Mono, with XLFD
Each of these fonts comes Roman, oblique, bold and bold oblique variants The TrueType version have glyphs covering the basic ASCII Unicode range, the Latin 1 range, as well as the Extended Latin range and some additional punctuation characters. In particular, these fonts include all the glyphs needed for ISO 8859 parts 1, 2, 3, 4, 9, 13 and 15, as well as all the glyphs in the Adobe Standard encoding and the Windows 3.1 character set.
The glyph coverage of the Type 1 versions is somewhat reduced, and only covers ISO 8859 parts 1, 2 and 15 as well as the Adobe Standard encoding.
The Luxi fonts are original designs by Kris Holmes and Charles Bigelow. Luxi fonts include seriffed, sans serif, and monospaced styles, in roman and oblique, and normal and bold weights. The fonts share stem weight, x-height, capital height, ascent and descent, for graphical harmony.
The character width metrics of Luxi roman and bold fonts match those of core fonts bundled with popular operating and window systems.
The license terms for the Luxi fonts are included in the file
COPYRIGHT.BH', as well as in the License document.
Charles Bigelow and Kris Holmes from Bigelow and Holmes Inc. developed the Luxi typeface designs in Ikarus digital format.
URW++ Design and Development GmbH converted the Ikarus format fonts to TrueType and Type1 font programs and implemented the grid-fitting "hints" and kerning tables in the Luxi fonts.
An earlier version of the Luxi fonts was made available under the name Lucidux. This name should no longer be used due to trademark uncertainties, and all traces of the Lucidux name have been removed from X11R7.6.
This section describes X11R7.6-specific enhancements to the core X11 fonts system.
The scalable font backends (Type 1 and TrueType) can
automatically re-encode fonts to the encoding specified in the
XLFD in `
fonts.dir'. For example, a `
fonts.dir' file can
contain entries for the Type 1 Courier font such as
cour.pfa -adobe-courier-medium-r-normal--0-0-0-0-m-0-iso8859-1 cour.pfa -adobe-courier-medium-r-normal--0-0-0-0-m-0-iso8859-2
which will lead to the font being recoded to ISO 8859-1 and ISO 8859-2 respectively.
Two of the scalable backends (Type 1 and the FreeType TrueType backend) use a common fontenc layer for font re-encoding. This allows these backends to share their encoding data, and allows simple configuration of new locales independently of font type.
Please note: the X-TrueType (X-TT) backend is not included in X11R7.6. That functionality has been merged into the FreeType backend.
In the fontenc layer, an encoding is defined by a name (such as
iso8859-1), possibly a number of aliases (alternate names), and
an ordered collection of mappings. A mapping defines the way the
encoding can be mapped into one of the target encodings known to
fontenc; currently, these consist of Unicode, Adobe glyph names,
and arbitrary TrueType “cmap”s.
A number of encodings are hardwired into fontenc, and are therefore always available; the hardcoded encodings cannot easily be redefined. These include:
iso8859-1: ISO Latin-1 (Western Europe);
iso8859-2: ISO Latin-2 (Eastern Europe);
iso8859-3: ISO Latin-3 (Southern Europe);
iso8859-4: ISO Latin-4 (Northern Europe);
iso8859-5: ISO Cyrillic;
iso8859-6: ISO Arabic;
iso8859-7: ISO Greek;
iso8859-8: ISO Hebrew;
iso8859-9: ISO Latin-5 (Turkish);
iso8859-10: ISO Latin-6 (Nordic);
iso8859-15: ISO Latin-9, or Latin-0 (Revised
koi8-r: KOI8 Russian;
koi8-u: KOI8 Ukrainian (see RFC 2319);
koi8-ru: KOI8 Russian/Ukrainian;
koi8-uni: KOI8 “Unified” (Russian, Ukrainian, and
koi8-e: KOI8 “European,” ISO-IR-111, or ECMA-Cyrillic;
apple-roman: these are only
likely to be useful with TrueType symbol fonts.
Additional encodings can be added by defining encoding files.
When a font encoding is requested that the fontenc layer doesn't
know about, the backend checks the directory in which the font file
resides (not necessarily the directory with
fonts.dir!) for a
file named `
encodings.dir'. If found, this file is scanned for
the requested encoding, and the relevant encoding definition file is
read in. The `mkfontdir' utility, when invoked with the
-e' option followed by the name of a directory containing
encoding files, can be used to automatically build `
files. Please see the mkfontdir(1)
manual page for more details.
A number of encoding files for common encodings are included with X11R7.6. Information on writing new encoding files can be found in Format of encodings directory files and Format of encoding files later in this document.
For TrueType and OpenType fonts, the FreeType backend scans the mappings in order. Mappings with a target of PostScript are ignored; mappings with a TrueType or Unicode target are checked against all the cmaps in the file. The first applicable mapping is used.
For Type 1 fonts, the FreeType backend first searches for a mapping with a target of PostScript. If one is found, it is used. Otherwise, the backend searches for a mapping with target Unicode, which is then composed with a built-in table mapping codes to glyph names. Note that this table only covers part of the Unicode code points that have been assigned names by Adobe.
Specifying an encoding value of
adobe-fontspecific for a
Type 1 font disables the encoding mechanism. This is useful with
symbol and incorrectly encoded fonts (see Incorrectly encoded fonts below).
If a suitable mapping is not found, the FreeType backend defaults to ISO 8859-1.
In order to use a font in an encoding that the font backend does
not know about, you need to have an `
encodings.dir' file either
in the same directory as the font file used or in a system-wide
/usr/share/fonts/X11/encodings/' by default).
encodings.dir' file has a similar format to
fonts.dir'. Its first line specifies the number of encodings,
while every successive line has two columns, the name of the encoding,
and the name of the encoding file; this can be relative to the current
directory, or absolute. Every encoding name should agree with the
encoding name defined in the encoding file. For example,
3 mulearabic-0 /usr/share/fonts/X11/encodings/mulearabic-0.enc mulearabic-1 /usr/share/fonts/X11/encodings/mulearabic-1.enc mulearabic-2 /usr/share/fonts/X11/encodings/mulearabic-2.enc
The name of an encoding must be specified in the encoding file's
STARTENCODING' or `
ALIAS' line. It is not enough to create
If your platform supports it (it probably does), encoding files may be compressed or gzipped.
encoding.dir' files are best maintained by the
`mkfontdir' utility. Please see the mkfontdir(1) manual page for more information.
The encoding files are “free form,” i.e. any string of
whitespace is equivalent to a single space. Keywords are parsed in a
non-case-sensitive manner, meaning that `
SiZE' all parse as the same keyword; on the other hand, case is
significant in glyph names.
Numbers can be written in decimal, as in `
256', in hexadecimal,
as in `
0x100', or in octal, as in `
Comments are introduced by a hash sign `
#'. A `
appear at any point in a line, and all characters following the
#' are ignored, up to the end of the line.
The encoding file starts with the definition of the name of the encoding, and possibly its alternate names (aliases):
STARTENCODING mulearabic-0 ALIAS arabic-0
The name of the encoding and its aliases should be suitable for use in
an XLFD font name, and therefore contain exactly one dash `
The encoding file may then optionally declare the size of the encoding. For a linear encoding (such as ISO 8859-1), the SIZE line specifies the maximum code plus one:
For a matrix encoding, it should specify two numbers. The first is
the number of the last row plus one, the other, the highest column
number plus one. In the case of `
(JIS X 0208(1990), double-byte encoding, high bit clear), it
SIZE 0x75 0x80
In the case of a matrix encoding, a `
FIRSTINDEX' line may be
included to specify the minimum glyph index in an encoding. The
FIRSTINDEX' is followed by two integers, the minimum row
number followed by the minimum column number:
FIRSTINDEX 0x20 0x20
In the case of a linear encoding, a `
FIRSTINDEX' line is not very
useful. If for some reason however you chose to include on, it should
be followed by a single integer.
Note that in most font backends inclusion of a `
has the side effect of disabling default glyph generation, and this
keyword should therefore be avoided unless absolutely necessary.
Codes outside the region defined by the `
FIRSTINDEX' lines are understood to be undefined. Encodings
default to linear encoding with a size of 256 (0x100). This means
that you must declare the size of all 16 bit encodings.
What follows is one or more mapping sections. A mapping section
starts with a `
STARTMAPPING' line stating the target of the mapping.
The target may be one of:
Unicode (ISO 10646):
a given TrueType “cmap”:
STARTMAPPING cmap 3 1
PostScript glyph names:
Every line in a mapping section maps one from the encoding being defined to the target of the mapping. In mappings with a Unicode or TrueType mapping, codes are mapped to codes:
0x21 0x0660 0x22 0x0661 ...
As an abbreviation, it is possible to map a contiguous range of codes in a single line. A line consisting of three integers
<it/start/ <it/end/ <it/target/
is an abbreviation for the range of lines
For example, the line
0x2121 0x215F 0x8140
is an abbreviation for
0x2121 0x8140 0x2122 0x8141 ... 0x215F 0x817E
Codes not listed are assumed to map through the identity (i.e. to
the same numerical value). In order to override this default mapping,
you may specify a range of codes to be undefined by using an
UNDEFINE 0x00 0x2A
or, for a single code,
PostScript mappings are different. Every line in a PostScript mapping maps a code to a glyph name
0x41 A 0x42 B ...
and codes not explicitly listed are undefined.
A mapping section ends with an
After all the mappings have been defined, the file ends with an
In order to make future extensions to the format possible, lines starting with an unknown keyword are silently ignored, as are mapping sections with an unknown target.
Type 1 symbol fonts should be installed using the
In an ideal world, all TrueType symbol fonts would be installed using
one of the
apple-roman encodings. A
number of symbol fonts, however, are not marked as such; such fonts
should be installed using
microsoft-cp1252, or, for older fonts,
In order to guarantee consistent results (especially between
Type 1 and TrueType versions of the same font), it is possible to
define a special encoding for a given font. This has already been done
ZapfDingbats font; see the file
A number of text fonts are incorrectly encoded. Incorrect encoding is sometimes done by design, in order to make a font for an exotic script appear like an ordinary Western text font on systems which are not easily extended with new locale data. It is often the result of the font designer's laziness or incompetence; for some reason, most people seem to find it easier to invent idiosyncratic glyph names rather than follow the Adobe glyph list.
There are two ways of dealing with such fonts: using them with the encoding they were designed for, and creating an ad hoc encoding file.
In the case of Type 1 fonts, the font designer can specify a
default encoding; this encoding is requested by using the
adobe-fontspecific' encoding in the XLFD name. Sometimes, the
font designer omitted to specify a reasonable default encoding, in
which case you should experiment with `
microsoft-win3.1'. (The encoding `
make sense for Type 1 fonts).
TrueType fonts do not have a default encoding. However, most TrueType
fonts are designed with either Microsoft or Apple platforms in mind,
so one of `
microsoft-win3.1', or `
apple-roman' should yield reasonable
It is always possible to define an encoding file to put the glyphs
in a font in any desired order. Again, see the
encodings/adobe-dingbats.enc' file to see how this is done.
By following the directions above, you will find yourself with a
number of fonts with unusual names --- with encodings such as
microsoft-win3.1' etc. In order
to use these fonts with standard applications, it may be useful to
remap them to their proper names.
This is done by writing a `
fonts.alias' file. The format of this file
is very simple: it consists of a series of lines each mapping an alias
name to a font name. A `
fonts.alias' file might look as follows:
"-ogonki-alamakota-medium-r-normal--0-0-0-0-p-0-iso8859-2" \ "-ogonki-alamakota-medium-r-normal--0-0-0-0-p-0-adobe-fontspecific"
(both XLFD names on a single line). The syntax of the
fonts.alias' file is more precisely described in the
mkfontdir(1) manual page.
The FreeType backend (formerly xfsft)
is a backend based on version 2 of the FreeType library (see the FreeType web site) and has
the X-TT functionalities for CJKV support provided by the After X-TT
Project (see the After X-TT Project web site). The FreeType backend has support for the
“fontenc” style of internationalisation (see the section called “The fontenc layer ”). This backend supports TrueType font files
*.ttf'), OpenType font files (`
*.otf'), TrueType Collections
*.ttc'), OpenType Collections (`
*.otc') and Type 1 font
*.pfa' and `
In order to access the faces in a TrueType Collection file, the face number must be specified in the fonts.dir file before the filename, within a pair of colons, or by setting the 'fn' TTCap option. For example,
refers to face 1 in the `
mincho.ttc' TrueType Collection file.
The new FreeType backend supports the extended
fonts.dir' syntax introduced by X-TrueType with a number
of options, collectively known as `TTCap'. A `TTCap' entry follows the
and should be specified before the filename. The new FreeType
almost perfectly supports TTCap options that are compatible with X-TT
1.4. The Automatic Italic (`
ai'), Double Strike (`
Bounding box Width (`
bw') options are indispensable in CJKV.
mincho.ttc -misc-mincho-medium-r-normal--0-0-0-0-c-0-jisx0208.1990-0 ds=y:mincho.ttc -misc-mincho-bold-r-normal--0-0-0-0-c-0-jisx0208.1990-0 ai=0.2:mincho.ttc -misc-mincho-medium-i-normal--0-0-0-0-c-0-jisx0208.1990-0 ds=y:ai=0.2:mincho.ttc -misc-mincho-bold-i-normal--0-0-0-0-c-0-jisx0208.1990-0 bw=0.5:mincho.ttc -misc-mincho-medium-r-normal--0-0-0-0-c-0-jisx0201.1976-0 bw=0.5:ds=y:mincho.ttc -misc-mincho-bold-r-normal--0-0-0-0-c-0-jisx0201.1976-0 bw=0.5:ai=0.2:mincho.ttc -misc-mincho-medium-i-normal--0-0-0-0-c-0-jisx0201.1976-0 bw=0.5:ds=y:ai=0.2:mincho.ttc -misc-mincho-bold-i-normal--0-0-0-0-c-0-jisx0201.1976-0
setup the complete combination of jisx0208 and jisx0201 using mincho.ttc only. More information on the TTCap syntax is found on the After X-TT Project page.
The FreeType backend uses the fontenc layer in order to support recoding of fonts; this was described in the section called “The fontenc layer ” and especially the section called “The FreeType backend ” earlier in this document.
When loading a proportional fonts which contain a huge number of glyphs,
the old FreeType delayed glyph rasterisation until the time at which
the glyph was first used. The new FreeType (libfreetype-xtt2) has an
improved `very lazy' metric calculation method to speed up the process when
loading TrueType or OpenType fonts. Although the X-TT module also
has this method, the "
vl=y" TTCap option must be set if you want to
use it. This is the default method for FreeType when it loads
multi-byte fonts. Even if you use a unicode font which has tens of
thousands of glyphs, this delay will not be worrisome as long as you use
the new FreeType backend -- its `very lazy' method is super-fast.
The maximum error of bitmap position using `very lazy' method is 1 pixel,
and is the same as that of a character-cell spacing. When the X-TT
backend is used with the `
vl=y' option, a chipped bitmap is displayed
with certain fonts. However, the new FreeType backend has minimal problem
with this, since it corrects left- and right-side bearings using
`italicAngle' in the TrueType/OpenType post table, and does automatic
correction of bitmap positions when rasterisation so that chipped bitmaps
are not displayed. Nevertheless if you don't want to use the `very lazy'
method when using multi-bytes fonts, set `
vl=n' in the TTCap option to
vl=n:luxirr.ttf -b&h-Luxi Serif-medium-r-normal--0-0-0-0-p-0-iso10646-1
Of course, both backends also support an optimisation for character-cell
fonts (fonts with all glyph metrics equal, or terminal fonts). A font
with an XLFD specifying a character-cell spacing `
c', as in
will not compute the metric for each glyph, but instead trust the font to be a character-cell font. You are encouraged to make use of this optimisation when useful, but be warned that not all monospaced fonts are character-cell fonts.
A computer text-processing system inputs keystrokes and outputs
glyphs, small pictures that are assembled on paper or on a
computer screen. Keystrokes and glyphs do not, in general, coincide:
for example, if the system does generate ligatures, then to the
sequence of two keystrokes <
i> will typically
correspond a single glyph. Similarly, if the system shapes Arabic
glyphs in a vaguely reasonable manner, then multiple different glyphs
may correspond to a single keystroke.
The complex transformation rules from keystrokes to glyphs are usually factored into two simpler transformations, from keystrokes to characters and from characters to glyphs. You may want to think of characters as the basic unit of text that is stored e.g. in the buffer of your text editor. While the definition of a character is intrinsically application-specific, a number of standardised collections of characters have been defined.
A coded character set is a set of characters together with a mapping from integer codes --- known as codepoints --- to characters. Examples of coded character sets include US-ASCII, ISO 8859-1, KOI8-R, and JIS X 0208(1990).
A coded character set need not use 8 bit integers to index characters. Many early systems used 6 bit character sets, while 16 bit (or more) character sets are necessary for ideographic writing systems.
Traditionally, typographers speak about typefaces and founts. A typeface is a particular style or design, such as Times Italic, while a fount is a molten-lead incarnation of a given typeface at a given size.
Digital fonts come in font files. A font file contains the information necessary for generating glyphs of a given typeface, and applications using font files may access glyph information in an arbitrary order.
Digital fonts may consist of bitmap data, in which case they are said to be bitmap fonts. They may also consist of a mathematical description of glyph shapes, in which case they are said to be scalable fonts. Common formats for scalable font files are Type 1 (sometimes incorrectly called ATM fonts or PostScript fonts), TrueType and OpenType.
The glyph data in a digital font needs to be indexed somehow. How this is done depends on the font file format. In the case of Type 1 fonts, glyphs are identified by glyph names. In the case of TrueType fonts, glyphs are indexed by integers corresponding to one of a number of indexing schemes (usually Unicode --- see below).
The X11 core fonts system uses the data in a font file to generate font instances, which are collections of glyphs at a given size indexed according to a given encoding.
X11 core font instances are usually specified using a notation known
as the X Logical Font Description (XLFD). An XLFD starts with a
-', and consists of fourteen fields separated by dashes,
Or particular interest are the last two fields `
specify the font instance's encoding.
A scalable font is specified by an XLFD which contains zeroes instead of some fields:
X11 font instances may also be specified by short name. Unlike an
XLFD, a short name has no structure and is simply a conventional name
for a font instance. Two short names are of particular interest, as
the server will not start if font instances with these names cannot be
opened. These are `
fixed', which specifies the fallback font to
use when the requested font cannot be opened, and `
specifies the set of glyphs to be used by the mouse pointer.
Short names are usually implemented as aliases to XLFDs; the
fixed' and `
cursor' aliases are defined in
Unicode (http://www.unicode.org) is a coded character set with the goal of uniquely identifying all characters for all scripts, current and historical. While Unicode was explicitly not designed as a glyph encoding scheme, it is often possible to use it as such.
Unicode is an open character set, meaning that codepoint assignments may be added to Unicode at any time (once specified, though, an assignment can never be changed). For this reason, a Unicode font will be sparse, meaning that it only defines glyphs for a subset of the character registry of Unicode.
The Unicode standard is defined in parallel with the international standard ISO 10646. Assignments in the two standards are always equivalent, and we often use the terms Unicode and ISO 10646 interchangeably.
When used in the X11 core fonts system, Unicode-encoded fonts should
have the last two fields of their XLFD set to `
X11R7.6 comes with extensive documentation in the form of manual
pages and typeset documents. Before installing fonts, you really should
read the fontconfig(3) and
mkfontdir(1) manual pages; other
manual pages of interest include X(7),
Xserver(1), xset(1), Xft(3), xlsfonts(1) and showfont(1). In addition, you may want to read the X Logical
Font Description document, by Jim Flowers, which is provided in the file
The comp.fonts FAQ, which is unfortunately no longer being maintained, contains a wealth of information about digital fonts.
Xft and Fontconfig are described on Keith Packard's Fontconfig site.
The xfsft home page has been superseded by this document, and is now obsolete; you may however still find some of the information that it contains useful. Joerg Pommnitz' xfsft page is the canonical source for the `ttmkfdir' utility, which is the ancestor of mkfontscale.
The author's software pages might or might not contain related scribbles and development versions of software.
The documentation of X-TrueType is available from the After X-TT Project page.
The IANA RFC documents, available from a number of sites throughout the world, often provide interesting information about character set issues; see for example RFC 373.