In migrating the font configuration mechanism out of Xft and into a
separate library, I have an opportunity to redefine the configuration
language to make it easier for external agents to parse and modify.
I've decided to give XML a try and see how it looks; other applications
have started migrating to this for configuration and it has a lot of
appeal.
Please find enclosed the proposed DTD and a sample font configuration file.
They have only been run through xmllint --valid; I have not started on any
related C code.
For those of you with more XML experience than I (that shouldn't be hard,
I just printed the XML spec this morning), please let me know if I'm doing
things in silly or unconventional ways. Also, please let me know if using
libxml is a bad idea; it seems a bit easier to use than expat.
If this transition goes well, I may propose that the XFree86 server
configuration file be transitioned to XML as well; the ability to have
external agents edit the file without needing a complete understanding of
the syntax should be very useful.
Keith Packard XFree86 Core Team Compaq Cambridge Research Lab
<!-- This is the Document Type Definition for font configuration files -->
<!ELEMENT fontconfig (dir |
cache |
include |
include_if |
match |
alias)* >
<!--
Add a directory that provides fonts
-->
<!ELEMENT dir EMPTY>
<!ATTLIST dir
dir CDATA #REQUIRED>
<!--
Define the per-user file that holds cache font information.
If the filename begins with '~', it is replaced with the users
home directory path.
-->
<!ELEMENT cache EMPTY>
<!ATTLIST cache
file CDATA #REQUIRED>
<!--
Reference another configuration file; note that this
is another complete font configuration file and not
just a file included by the XML parser.
Set 'ignore_missing' to 'yes' if errors are to be ignored.
If the filename begins with '~', it is replaced with the users
home directory path.
-->
<!ELEMENT include EMPTY>
<!ATTLIST include
ignore_missing (no|yes) "no"
file CDATA #REQUIRED>
<!--
Aliases are just a special case for multiple match elements
They are syntactically equivalent to:
<match>
<test name="family">
<string value=[family]/>
</test>
<edit name="family" mode="prepend">
<string value=[prefer]/>
...
</edit>
<edit name="family" mode="append">
<string value=[accept]/>
...
</edit>
<edit name="family" mode="append_last">
<string value=[default]/>
...
</edit>
</match>
-->
<!ELEMENT alias (prefer?, accept?, default?)>
<!ATTLIST alias
family CDATA #REQUIRED>
<!ELEMENT prefer (family)*>
<!ELEMENT accept (family)*>
<!ELEMENT default (family)*>
<!ELEMENT family EMPTY>
<!ATTLIST family
family CDATA #REQUIRED>
<!ENTITY % expr
'number|string|name|matrix|boolean_or|boolean_and|eq|not_eq|less|less_eq|more|more_eq|plus|minus|times|divide|not|if'>
<!--
Match and edit patterns.
If 'target' is 'pattern', execute the match before selecting a font.
if 'target' is 'font', execute the match on the result of a font
selection.
-->
<!ELEMENT match (test*, edit*)>
<!ATTLIST match
target (pattern|font) "pattern">
<!--
Match a field in a pattern
if 'qual' is 'any', then the match succeeds if any value in the field matches.
if 'qual' is 'all', then the match succeeds only if all values match.
-->
<!ELEMENT test (%expr;)>
<!ATTLIST test
qual (any|all) "any"
name CDATA #REQUIRED
compare (eq|not_eq|less|less_eq|more|more_eq) "eq">
<!--
Edit a field in a pattern
The enclosed values are used together to edit the list of values
associated with 'name'.
If 'name' matches one of those used in a test element for this match element:
if 'mode' is 'assign', replace the matched value.
if 'mode' is 'assign_replace', replace all of the values
if 'mode' is 'prepend', insert before the matched value
if 'mode' is 'append', insert after the matched value
if 'mode' is 'prepend_first', insert before all of the values
if 'mode' is 'append_last', insert after all of the values
If 'name' doesn't match any of those used in a test element:
if 'mode' is 'assign' or 'assign_replace, replace all of the values
if 'mode' is 'prepend' or 'prepend_first', insert before all of the values
if 'mode' is 'append' or 'append_last', insert after all of the values
-->
<!ELEMENT edit (%expr;)*>
<!ATTLIST edit
name CDATA #REQUIRED
mode (assign|assign_replace|prepend|append|prepend_first|append_last)
"assign">
<!--
Elements of expressions follow
-->
<!ELEMENT number EMPTY>
<!ATTLIST number
value CDATA #REQUIRED>
<!ELEMENT string EMPTY>
<!ATTLIST string
value CDATA #REQUIRED>
<!ELEMENT name EMPTY>
<!ATTLIST name
name CDATA #REQUIRED>
<!ELEMENT matrix (number,number,number,number)>
<!ELEMENT boolean_or (%expr;)*>
<!ELEMENT boolean_and (%expr;)*>
<!ELEMENT eq (%expr;)*>
<!ELEMENT not_eq (%expr;)*>
<!ELEMENT less (%expr;)*>
<!ELEMENT less_eq (%expr;)*>
<!ELEMENT more (%expr;)*>
<!ELEMENT more_eq (%expr;)*>
<!ELEMENT plus (%expr;)*>
<!ELEMENT minus (%expr;)*>
<!ELEMENT times (%expr;)*>
<!ELEMENT divide (%expr;)*>
<!ELEMENT not (%expr;)>
<!ELEMENT if ((%expr;), (%expr;), (%expr;)?)>
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<!-- /etc/fonts.conf file to configure system font access -->
<fontconfig>
<!--
Find true type fonts in this directory
-->
<dir dir="/usr/X11R6/lib/X11/fonts/truetype"/>
<!--
Accept deprecated 'mono' alias, replacing it with 'monospace'
-->
<match target="pattern">
<test qual="any" name="family"><string value="mono"/></test>
<edit name="family" mode="assign"><string value="monospace"/></edit>
</match>
<!--
Load per-user customization file
-->
<include ignore_missing="yes" file="~/.fonts.conf"/>
<!--
Alias well known font names to available TrueType fonts
-->
<alias family="Times">
<prefer><family family="Times New Roman"/></prefer>
<default><family family="serif"/></default>
</alias>
<alias family="Helvetica">
<prefer><family family="Verdana"/></prefer>
<default><family family="sans"/></default>
</alias>
<alias family="Courier">
<prefer><family family="Courier New"/></prefer>
<default><family family="monospace"/></default>
</alias>
<!--
Provide required aliases for standard names
-->
<alias family="serif">
<prefer><family family="Times New Roman"/></prefer>
</alias>
<alias family="sans">
<prefer><family family="Verdana"/></prefer>
</alias>
<alias family="monospace">
<prefer><family family="Andale Mono"/></prefer>
</alias>
</fontconfig>
