This change should move us forward toward emoji support, as we are no
longer limited by our own OpenType implementation, which was failing
to parse the TrueType Collection format used to store emoji fonts
(at least on macOS).
Currently we rely on parser returning an error if encoded data cannot be
parsed into a valid WOFF or WOFF2 font, which is not going to be true
after switching to Skia that sometimes does not fail even if a data does
not represent a valid font.
This is only used for CSS style sheets. One case wants it as a String,
and the others don't care, but will in future also want to have the
source as a String.
Instead of CSSColorValue holding a Gfx::Color, make it an abstract class
with subclasses for each different color function, to match the Typed-OM
spec. This means moving the color calculations from the parsing code to
the `to_color()` method on the style value.
This lets us have calc() inside a color function, instead of having to
fully resolve the color at parse time. The canvas fillStyle tests have
been updated to reflect this.
The other test change is Screenshot/css-color-functions.html: previously
we produced slightly different colors for an alpha of 0.5 and one of
50%, and this incorrect behavior was baked into the test. So now it's
more correct. :^)
Soon, CSSColorValue will be an abstract class, and we'll instead create
a CSSRGB, CSSHSL, or other specific color type from the Typed-OM spec.
However, it's still useful to have an easy "just give me a style value
for this color" method. So change the name to distinguish this from the
usual StyleValue::create() methods.
We previously had 4 single-instance StyleValues for these keywords.
CSS-Typed-OM expects them keywords to be exposed as CSSKeywordValue, so
it's simpler to treat them the same. The single-instance behaviour is
kept by having StyleValue::create() use a cached instance for each of
these.
For a long time, we've used two terms, inconsistently:
- "Identifier" is a spec term, but refers to a sequence of alphanumeric
characters, which may or may not be a keyword. (Keywords are a
subset of all identifiers.)
- "ValueID" is entirely non-spec, and is directly called a "keyword" in
the CSS specs.
So to avoid confusion as much as possible, let's align with the spec
terminology. I've attempted to change variable names as well, but
obviously we use Keywords in a lot of places in LibWeb and so I may
have missed some.
One exception is that I've not renamed "valid-identifiers" in
Properties.json... I'd like to combine that and the "valid-types" array
together eventually, so there's no benefit to doing an extra rename
now.
Not every value in a StyleProperties will be non-null by the time we
perform `revert`, so let's make a specialized function for reverting a
property instead of using the path that requires the value to be
non-null.
We were saving to source declarations for *every* property, even though
we only ever looked it up for animation-name.
This patch gets rid of the per-property source pointer and we now keep
a single pointer to the animation-name source only.
This shrinks StyleProperties from 6512 bytes to 4368 bytes per instance.
The :host family of pseudo class selectors select the shadow host
element when matching against a rule from within the element's shadow
tree.
This is a bit convoluted due to the fact that the document-level
StyleComputer keeps track of *all* style rules, and not just the
document-level ones.
In the future, we should refactor style storage so that shadow roots
have their own style scope, and we can simplify a lot of this.
This change removes wrappers inherited from Gfx::Typeface for WOFF and
WOFF2 fonts. The only purpose they served is owning of ttf ByteBuffer
produced by decoding a WOFF/WOFF2 font. Now new FontData class is
responsible for holding ByteBuffer when a font is constructed from
non-externally owned memory.
We already have a FlyString of its value from parsing, and most users
also want a FlyString from it, so let's use that instead of converting
backwards and forwards.
The two users that did want a String are:
- Quotes, which make sense as FlyString instead, so I've converted that.
- Animation names, which should probably be FlyString too, but the code
currently also allows for other kinds of StyleValue, and I don't want
to dive into this right now to figure out if that's needed or not.
Typeface is a more widely used name for the data represented by
class previously named VectorFont.
Now:
- Typeface represents decoded font that is not ready for rendering
- ScaledFont represents the combination of typeface and size for
rendering
The values aren't that complex, so it doesn't make much sense to have a
dedicated generator for them. Parsing them manually also allows us to
have much more control over the produced values, so as a result of this
change, EasingStyleValue becomes much more ergonomic.
This closes the window at WebContent process startup where we were
relying on Gfx::FontDatabase having some resolvable value in its default
font query.
We'll want to explicitly load fonts from FontFace and other Web APIs
in the future. A future refactor should also move this completely away
from StyleComputer and call it something like 'FontCache'.
For bitmap fonts, we will often not have an exact match for requested
sizes. Return the closest match instead of a nullptr.
LibWeb is currently the only user of this API. If it needs to be
configurable in the future to only allow exact matches, we can add a
parameter or another method at that time.
Rather than each element which supports dimension attributes needing to
implement parsing the attributes and setting the appropriate style, we
can generalize this functionality. This will also make each element more
closely resemble the spec text, as we will be effectively declaring, for
example, "The img element supports dimension attributes" in code.
As the parser was trying to directly unwrap an unresolved duration.
Currently we are outputting the wrong results for the serialized
duration, but this is still a step forwards.
Fixes a crash seen on: https://evaparish.com/blog/how-i-edit
This way we can just leave it alone if the property hasn't changed.
Notably, if the play-state property has been set to 'paused', and then
the user gets the animation with JS and calls .play() on it, it should
start playing despite the play-state property value.
We don't want to always invoke the .play() method if an animation is
relevant and had a play state of running, as the play state is
essentially just "paused" or "not paused". We replace that relevancy
check with the inverse of the pause check so we don't constantly call
.play() on animations that are finished.
Also duplicates and moves the temporary context into both blocks, since
most of the time neither condition will be true.
Given a selector like `.foo .bar #baz`, we know that elements with
the class names `foo` and `bar` must be present in the ancestor chain of
the candidate element, or the selector cannot match.
By keeping track of the current ancestor chain during style computation,
and which strings are used in tag names and attribute names, we can do
a quick check before evaluating the selector itself, to see if all the
required ancestors are present.
The way this works:
1. CSS::Selector now has a cache of up to 8 strings that must be present
in the ancestor chain of a matching element. Note that we actually
store string *hashes*, not the strings themselves.
2. When Document performs a recursive style update, we now push and pop
elements to the ancestor chain stack as they are entered and exited.
3. When entering/exiting an ancestor, StyleComputer collects all the
relevant string hashes from that ancestor element and updates a
counting bloom filter.
4. Before evaluating a selector, we first check if any of the hashes
required by the selector are definitely missing from the ancestor
filter. If so, it cannot be a match, and we reject it immediately.
5. Otherwise, we carry on and evaluate the selector as usual.
I originally tried doing this with a HashMap, but we ended up losing
a huge chunk of the time saved to HashMap instead. As it turns out,
a simple counting bloom filter is way better at handling this.
The cost is a flat 8KB per StyleComputer, and since it's a bloom filter,
false positives are a thing.
This is extremely efficient, and allows us to quickly reject the
majority of selectors on many huge websites.
Some example rejection rates:
- https://amazon.com: 77%
- https://github.com/SerenityOS/serenity: 61%
- https://nytimes.com: 57%
- https://store.steampowered.com: 55%
- https://en.wikipedia.org: 45%
- https://youtube.com: 32%
- https://shopify.com: 25%
This also yields a chunky 37% speedup on StyleBench. :^)
When iterating through a @keyframes rule, it isn't possible to resolve
unresolved style properties since there are no elements. This change
allows those properties to simply pass through this helper function.
