Based very scientifically on what's listed here:
https://harfbuzz.github.io/what-does-harfbuzz-do.html
I've moved the code into LibGfx because including a HarfBuzz header
directly from LibWeb is a little unpleasant. But the Gfx::FontTech enum
follows the CSS definitions for font features for simplicity.
TrueType collections are supported. SVG and Embedded OpenType are not,
but they're not widely supported by other browsers so that's fine.
Most of the features are completely supported by HarfBuzz, so we can
just return true. Graphite support is optional (and it appears we use a
build of HarfBuzz without it) but there's a define we can check.
Incremental Font Transfer is a whole separate thing that we definitely
don't support yet.
This function attempts to resolve `lighter` and `bolder`, which we don't
want to do when serializing - that should happen in style computation.
This has the unexpected bonus of 37 more WPT passes!
We don't want to reset the values of `font-variant-*` here, as that will
override whatever our parsed font-variant-css2 was, so stop doing that.
Also, font-stretch is mentioned in the spec, but it's a legacy name
alias for font-width, so we don't need to do anything for it.
Gets us 319 WPT passes!
This gives us a more human-looking serialization of numbers by default,
and in case a fixed number of decimal digits is actually wanted, we
still have the 'f' specifier.
There's discussion in the linked spec issue, but the short version is,
this algorithm will see "foo,bar," as a list of two groups, with "foo"
in the first group and "bar" in the second. However, users of this want
to get a list of three groups, with the last one being empty. So, do
that!
This commit disallows "default" as a font-family name, when the name is
not quoted because unquoted names are treated as custom-idents, for
which the name "default" is not allowed.
CSSFontFaceRule now stores its values as a CSSFontFaceDescriptors, with
a ParsedFontFace produced on request. This is exposed via the `style`
attribute, so we pass a lot of tests that try to read values from
that.
We have one test regression, which we passed by mistake before: The test
wanted to ensure we don't allow `@font-face` nested inside other rules.
We passed it just because we discarded any `@font-face` without a
`font-family`. What we're supposed to do is 1) keep at-rules with
missing required descriptors and just not use them, and 2) reject
certain ones when nested.
We may want to cache the ParsedFontFace in the future, but I didn't here
because 1) it's called rarely, and 2) that would mean knowing to
invalidate it when the CSSFontFaceDescriptors changes, which isn't
obvious to me right now.
This gets us 37 new subtest passes in css/css-values, and 13 passes in
our other in-tree tests (and probably some random other ones!)
As noted in comments, a few parts of this algorithm have ad-hoc
behaviour to handle some issues in the spec.
The spec wants these keywords to appear in a particular order when
serialized, so let's just put them in that order during parsing.
This also fixes a bug where we didn't reject `font-variant-east-asian`
that contains `normal` alongside another value.
Also, rather than always parsing them as a StyleValueList, parse single
values on their own, and then support that in the to_font_variant_foo()
methods.
Without this, we'd happily parse `font-variant-caps: small-caps potato`
as just `small-caps` and ignore the fact that unused tokens were left
over.
This fix gets us some WPT subtest passes, and removes the need for a
bespoke parsing function for font-variant-caps.
Without this, getting a property's value from `element.style.foo` would
fail if `foo` is a shorthand property which has a longhand that is also
a shorthand. For example, `border` expands to `border-width` which
expands to `border-top-width`.
This is because we used `property()` to get a longhand's value, but this
returns nothing if the property is a shorthand.
This commit solves that by moving most of get_property_value() into a
separate method that returns a StyleProperty instead of a String, and
which calls itself recursively for shorthands. Also move the manual
shorthand construction out of ResolvedCSSStyleDeclaration so that all
CSSStyleDeclarations can use it.
