The UUID files would be placed in each font directory to provide the
unique cache name, independent of path, for that directory. The UUID
files are undesireable for a couple of reasons:
1) They must be placed in the font directories to be useful. This
requires modifying the font directories themselves, introducing
potential visible timestamp changes when running multiple
applications, and makes the cache processing inconsistent between
applications with permission to write to the font directories and
applications without such permission.
2) The UUID contents were generated randomly, which makes the font
cache not reproducible across multiple runs.
One proposed fix for 2) is to make the UUID dependent on the font
directory path, but once we do that, we can simply use the font
directory path itself as the key as the original MD5-based font cache
naming mechanism did.
The goal of the UUID file mechanism was to fix startup time of
flatpaks; as the font path names inside the flatpak did not match the
font path names in the base system, the font cache would need to be
reconstructed the first time the flatpak was launched.
The new mechanism for doing this is to allow each '<dir>' element in
the configuration include a 'map' attribute. When looking for a cache
file for a particular directory, if the directory name starts with the
contents of the <dir> element, that portion of the name will be
replaced with the value of the 'map' attribute.
Outside of the flatpak, nothing need change -- fontconfig will build
cache files using real directory names.
Inside the flatpak, the custom fonts.conf file will now include
mappings such as this:
<dir map="/usr/share/fonts">/run/host/fonts</dir>
When scanning the directory /run/host/fonts/ttf, fontconfig will
use the name /usr/share/fonts/ttf as the source for building the cache
file name.
The existing FC_FILE replacement code used for the UUID-based
implementation continues to correctly adapt font path names seen by
applications.
v2:
Leave FcDirCacheCreateUUID stub around to avoid removing
public API function.
Document 'map' attribute of <dir> element in
fontconfig-user.sgml
Suggested-by: Akira TAGOH <akira@tagoh.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
Whilst working on the Reproducible Builds[0] effort, we noticed that
fontconfig generates unreproducible cache files.
This is due to fc-cache uses the modification timestamps of each
directory in the "checksum" and "checksum_nano" members of the _FcCache
struct. This is so that it can identify which cache files are valid
and/or require regeneration.
This patch changes the behaviour of the checksum calculations to prefer
the value of the SOURCE_DATE_EPOCH[1] environment variable over the
directory's own mtime. This variable can then be exported by build
systems to ensure reproducible output.
If SOURCE_DATE_EPOCH is not set or is newer than the mtime of the
directory, the existing behaviour is unchanged.
This work was sponsored by Tails[2].
[0] https://reproducible-builds.org/
[1] https://reproducible-builds.org/specs/source-date-epoch/
[2] https://tails.boum.org/
just setting FC_MATCH=3 shows a lot of information and hard to keep on track for informamtion
which is really necessary to see. to use this more effectively, added FC_DBG_MATCH_FILTER to
see for what one really want to see. it takes a comma-separated-list of object names.
If you want to see family name only, try like this:
FC_DBG_MATCH_FILTER=family FC_DEBUG=4096 fc-match
debugging output will be filtered out and see family only in the result.
Add two edit mode, "delete" and "delete_all".
what values are being deleted depends on <test> as documented.
if the target object is same to what is tested, matching value there
will be deleted. otherwise all of values in the object will be deleted.
so this would means both edit mode will not take any expressions.
e.g.
Given that the testing is always true here, the following rules:
<match>
<test name="foo" compare="eq">
<string>bar</string>
</test>
<edit name="foo" mode="delete"/>
</match>
will removes "bar" string from "foo" object. and:
<match>
<test name="foo" compare="eq">
<string>foo</string>
</test>
<edit name="bar" mode="delete"/>
</match>
will removes all of values in "bar" object.
Warn if the multiple values is set to <test>, including the case of
in <alias> because the behavior isn't intuitive since so many users
is asking for a help to get things working for their expectation.
Use multiple <match>s or <alias>es for OR operator and
multiple <test>s for AND operator.
Allows reading configuration files, fonts and cache files from
the directories where the XDG Base Directory Specification defines.
the old directories are still in the configuration files for
the backward compatibility.
Add a new attribute `ignore-blanks' to <test>.
When this is set to "true", any blanks in the string will be ignored
on comparison. This takes effects for compare="eq" or "not_eq" only.
Also changed the behavior of the comparison on <alias> too.
Stop using mmap() if the cache file is stored on NFS.
also added FONTCONFIG_USE_MMAP environment variable to enforce the use of
or not the use of mmap(2) regardless of what the filesystem the cache files
are stored on.
David Turner has modified FreeType to be able to render sub-pixel decimated
glyphs using different methods of filtering. Fontconfig needs new
configurables to support selecting these new filtering options. A patch
follows that would correspond to one available for Cairo in bug 10301.
The Delicious family includes one named Delicious Heavy, a bold variant
which is unfortunately marked as having normal weight. Because the family
name is 'Delicious', fontconfig accidentally selects this font instead of
the normal weight variant. The fix here rewrites the scanned data by running
the scanned pattern through a new substitution sequence tagged with
<match target=scan>; a sample for the Delicious family is included to
demonstrate how it works (and fix Delicious at the same time).
Also added was a new match predicate -- the 'decorative' predicate which is
automatically detected in fonts by searching style names for key decorative
phrases like SmallCaps, Shadow, Embosed and Antiqua. Suggestions for
additional decorative key words are welcome. This should have little effect
on font matching except when two fonts share the same characteristics except
for this value.
Limited FC_DEBUG documentation (just shows values and vague idea of what
they're related to). Also document \ escape syntax for font names, including
how family name and values have different escape requirements.
Akira TAGOH
Keith Packard
Chris Lamb
Tom Anderson
Alan Coopersmith
Behdad Esfahbod
Brad Hards
Sylvain Pasche
Peter Breitenlohner
Keith Packard
Patrick Lam