Re: Qt, GNOME, and fonts
Le lundi 17 février 2020 à 16:08 -0700, Jerry James a écrit :
Hi,
I am trying to track down a font problem with MuseScore:
https://bugzilla.redhat.com/show_bug.cgi?id=1790829
The problem is that everything is displayed in Cantarell, no matter
which font the user actually selects. In the style menu, one can pop
up a list of fonts to choose from, and even though every font on the
system is displayed by name, the text samples are all displayed in
Cantarell.
I’m neither a QT nor Musescore user. However, I know how things should
have been done to work reliably. So I'll put it there and let you find
where one of the app authors though it smart to play fast and loose.
First, Muse Score should install its fonts in the system font store,
use standard unicode points to render, and rely on fontconfig to
compute the best font containing those symbols given user-provided font
preferences. (I suppose, musical symbols Unicode.org range,
https://unicode.org/charts/PDF/U1D100.pdf). Eventually, contributing a
music orth file to fontconfig to make selection easier if none is
present yet.
That would make rendering work regardless of the font family selected,
as long as a font containing music symbols was present on system.
Maybe that’s the case today, or maybe Muse Score relies on non-unicode
fonts (or fonts using a PUA area) in a private directory. Private or
non unicode fonts are begging for breakage, as far as I am concerned.
Second, QT should interface properly with fontconfig and honor its
aliases and fallbacks in its selectors (that wasn't the case a long
time ago, I assume the bugs have been fixed since, but maybe I'm
wrong).
Third, GNOME should go back to using fontconfig directly as it did in
the past, instead of trying to override it with a vanity font declared
in a private non interoperable registry, enforced by overriding default
fontconfig queries in GNOME APIs. (vanity font that could not be
accepted as default font either Fedora or upstream, fontconfig side,
because its coverage is too small, and does not pass any serious i18n
test).
That’s not rocket science, drop a file in $XDG_CONFIG_HOME/fonts
defining the system-ui alias to whatever GNOME wants it to be, and you
get instant interoperability with non-GNOME apps (KDE, GTK, etc). If
the file is already present, do nothing, assume the user already
defined his prefered UI font.
Interoperability means thing like the CSS 4 system-ui selector work in
all compliant browsers without needing a special GNOME frobation.
If you want to be fancy go XDG or fontconfig to define a standard
filename all DE use, so different DEs do not stomp on one another.
Regards,
--
Nicolas Mailhot