Previously, font selection ignored the Unicode emoji presentation of a
code point. Emoji-capable code points were always resolved through
pre-baked color emoji and symbol fonts. Text-default code points which
lacked the `Emoji_Presentation` property, were therefore rendered as
color emoji rather than text. We now classify each code point's default
presentation from its `Emoji_Presentation` property and any trailing
variation selector.
Enable -Wexit-time-destructors for all in-tree library targets and
update process-lifetime library statics so they no longer register
exit-time destructors. Long-lived caches, lookup tables, singleton
registries, and generated constants now use NeverDestroyed or leaked
references where the data is intended to live until process exit.
Update LibWeb, LibLine, and the binding generators so regenerated
sources follow the same rule instead of reintroducing destructed
statics.
Previously we would resolve font features
(https://drafts.csswg.org/css-fonts-4/#feature-variation-precedence)
per element, while this works for the current subset of the font feature
resolution algorithm that we support, some as yet unimplemented parts
require us to know whether we are resolving against a CSS @font-face
rule, and if so which one (e.g. applying descriptors from the @font-face
rule, deciding which @font-feature-values rules to apply, etc).
To achieve this we store the data required to resolve font features in a
struct and pass that to `FontComputer` which resolves the font features
and stores them with the computed `Font`.
We no longer need to invalidate the font shaping cache when features
change since the features are defined per font (and therefore won't ever
change).
While our default font supporting variations is unlikely, this is
nevertheless required for our fallback font to be considered equal to
it's non-default/fallback equivalent (i.e. `font-family: serif`) which
in turn is required for LineBuilder to merge chunks into a single
fragment.
When rendering text, if none of the fonts in the cascade list contain a
glyph for a given code point, we now query Skia's font manager to find
a system font that can render it.
this commit also introduces GlobalFontConfig class that is now
responsible for fontconfig initialization. it seems sane, even thought
FcInit's docs state that if the default configuration has already been
loaded, this routine does nothing.
the goal is to rely on fontconfig for font directory resolution. it
doesn't seem like it would be appropritate to call to fontconfig funcs
from within the LibCore.
i'm not 100% confident that FontDatabase is the correct place.. seems
okay?
