Pass the requested font weight and slope to generic_font_name() and use
them to select the most suitable font family. Families that have the
exact requested weight are strongly preferred, followed by families with
more style variety.
This ensures that when CSS requests bold text with a generic font family
like `serif`, we select a family that actually supports bold weights
rather than one that only has regular weight.
Co-authored-by: Jelle Raaijmakers <jelle@ladybird.org>
WebView::FontPlugin was the only implementation of the abstract
FontPlugin base class. Its dependencies (LibGfx, LibCore) are
already visible to LibWeb.
Remove the virtual dispatch by making FontPlugin concrete and
absorbing the WebView::FontPlugin implementation directly.
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.
