'salt' attribute affects a cache filename to generate different name from directory name.
This is useful when sharing caches with host on sandbox and/or give a filename differently:
<dir salt="randomdata">/usr/share/fonts</dir>
<remap-dir as-path="/usr/share/fonts" salt="salt for /usr/share/fonts on host">/run/host/fonts</remap-dir>
Applications can read caches as-is for fonts on /run/host/fonts where is mounted from host.
and write a cache for their own fonts on /usr/share/fonts with different name.
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>
realfilename is the file name after sysroot adjustments. It should be used
instead of filename in the call to FcOpen() which forwards the name directly to
open().
Though I don't explicitly request a sysroot, I was getting error messages saying
"failed reading config file". This CL fixes the error spam.
Trying to address what these configuration files really do.
This change allows to see the short description that mention
the purpose of the content in the config file and obtain
them through API.
This change also encourage one who want to make some UI for
the user-specific configuration management. it is the main
purpose of this change for me though.
Aside from that, I've also made programs translatable. so
we see more dependencies on the build time for gettext,
and itstool to generate PO from xml.
Paths starting with '/' don't make sense on W32 as-is,
prepend the installation root directory to them.
This allows the cache to be contained within a particular
fontconfig installation (as long as the default
--with-cache-dir= is overriden at configure time).
This feature requires the FreeType 2.5.1 or later at the build time.
Besides <range> element allows <double> elements with this changes.
This may breaks the cache but not bumping in this change sets at this moment.
please be aware if you want to try it and run fc-cache before/after to
avoid the weird thing against it.
Akira TAGOH
Keith Packard
Tom Anderson
Alexander Kanavin
Behdad Esfahbod
Patrick Haller
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