Resolve prelude-less @scope roots from the owning stylesheet context
during matching. This lets implicit scoped declarations target a style
element's parent. It also lets implicit shadow-root scopes use the
shadow host as the scoping root.
Use StyleValue's computational-independence predicate when deciding
which specified values to retain for inherited-style recomputation.
Compound values such as shadows, filters, lists, and calc trees now
reuse their existing dependency tracking instead of the old bare-length
check.
Treat missing tuple entries and keyword-only edge offsets as
computationally independent. These nullable slots are part of the
parsed value representation, and the inherited dependency tracking now
uses the shared computational-independence query for specified values.
Add viewport resize coverage for media query changes that update root
font metrics while a descendant uses font-relative lengths inside
box-shadow and filter values.
Record when computed properties depend on viewport metrics while
resolving lengths. Carry that information through font metrics so
font-relative lengths can be associated with viewport-sized fonts.
This keeps the dependency tracking local to style computation and gives
later viewport resize invalidation a way to find affected elements.
`@scope (a) to (b) {}` applies its contained style rules to elements
that have `a` as a parent, and do not have `a b` as a parent. Both the
`a` and `b` selector lists are optional.
Because it's situational whether a `@scope` will apply to a given
element, we store the ancestor scope on the `MatchingRule`, similar to
`@container`, and then determine during matching whether all the parent
`@scope`s match or not.
The rules for how selectors inside `@scope` are adjusted and interpreted
are a bit confusing. Unlike for other at-rules, nested style rules
inside `@scope` do not get a leading `&` added during parsing. To
support this, `adapt_nested_relative_selector_list()` now takes a flag
for whether its parent is a `@scope` or not.
`@scope` can also contain nested declarations without itself being
nested inside a style rule.
When determining their selectors, nested declarations rules adopt the
`@scope`'s scoping root if it has one, or otherwise fall back to the
parent element of the `<style>` element (not implemented here,) or the
`:root`. These are required to have zero specificity, so we wrap the
selector in `:where()`.
This is preparation for nested declarations inside `@scope`. User code
no longer makes assumptions about there being a style rule parent, as
there may not be one.
We cache the absolutized selectors because `@scope` will require us to
modify the parent's selectors instead of using them directly.
Track explicit inherit of non-inherited properties only on the direct
parent shadow root. A deeper descendant with margin-left: inherit still
inherits from its own parent, so a host margin change does not require
marking every ancestor as possibly affected.
Extend the shadow-root inherited style test to cover both the direct
child case that must still update and the deeper descendant case that
must not trigger broad inherited-style recomputation.
Track when style recomputation may require inherited-style work in a
shadow tree, and use that signal when crossing from a shadow host into
its shadow root. Shadow descendants can explicitly inherit normally
non-inherited host properties, so any host style change may need
inherited-style recomputation there.
Use the CSS property definition to tell whether changed longhands need
to propagate to shadow descendants. Do the same after recomputing
inheritance-dependent values, such as host font-size: 2em after a parent
font-size change.
The shadow DOM tests cover inline and class-driven inherited host style
changes, explicit inherit for non-inherited host properties, relative
units on hosts, and nested slotted inheritance updates.
Previously we applied them ad-hoc when computing the style for the
referenced element but we now apply it as part of the cascade. This
fixes a couple bugs:
- Computing the style for the pseudo-element (rather than the
referenced element itself) as we do in the case we don't have a
layout node in `get_direct_property` now includes the inline style.
- Inline style is applied according to the cascade (i.e. it can be
overriden by non-inline `!important` styles).
- Properties go through the computation process.
e.g., `@container (width >= 300px) {}` and similar.
During style computation, flag any elements whose style depends on a
size container. Then re-evaluate their style after the initial layout
has been computed and size containers have a size. This may take
multiple passes, as these may have further descendants that depend on
their size, etc. We limit this to 8 passes currently.
SizeFeature itself is very similar to MediaFeature, but queries the
container element instead. There are only 6 size features specified, so
they're hard-coded instead of generated from JSON.
Also add a counter test for the narrower restyle path.
We now apply first letter styles by splitting text with a first-letter
style applied into 2 `TextSliceNode` objects. The
`DOM::Text` layout node always points at the non first-letter slice
and the first-letter slice is reachable via
`TextSliceNode::first_letter_slice()`.
First letter splitting works by `TreeBuilder` walking a block
container's inline descendants to find the first typographic letter
unit per the pattern given in css-pseudo level 4, which is then
wrapped in an anonymous inline box styled with the `::first-letter`
computed properties.
Consumers that map between DOM offsets and layout geometry
are updated to visit all slices of a `DOM::Text` through
`TextOffsetMapping`.
MatchingRules now have a container_rule member which stores the nearest
ancestor CSSContainerRule, if any. When populating the rule cache, we
maintain a stack of CSSContainerRules that we are within, and use
record the last one on the MatchingRule, so that it's O(1) instead of
having to walk up the rule's ancestors each time. This does mean we
have reimplement some "for each rule" code.
When collecting rules to apply to an element, we see if the MatchingRule
has a container_rule, and if so, we evaluate that rule's query to see
if the element has a matching container. We then also match any ancestor
container rules, using the cached parent container rule.
Add a custom test to cover the case of nested name-only `@container`s,
which WPT lacks currently as far as I can tell.
Previously, and according to the spec, `a::part(foo)::before` would be a
single CompoundSelector, even though it matches against 3 different
targets. This meant some awkward swapping of targets in the middle of
matching, and in particular it made `::part()` and `::slotted()` quite
hacky, requiring them to track extra data on the MatchContext to then
use later. This was scattered around and difficult to follow.
Partly inspired by Gecko, this commit instead introduces an invisible
PseudoElement combinator. After parsing a selector, we find any
CompoundSelectors that contain a pseudo-element and split them up, so
that each CompoundSelector only has a single target in the end. Where
the pseudo-element was at the start of a CompoundSelector, we insert an
invisible universal selector before it to represent its originating
element.
So now, a CompoundSelector deals with one target, and switching targets
is done at the combinator.
The one inconsistency is that we match the target of ::slotted()
and ::part() in pseudo_element_transition_target(), instead of before
then when processing the SimpleSelector. This is to avoid repeating the
same computations twice.
No outward-facing behaviour changes, though the invalidation metrics
have changed.
Previously we were inconsistent by generating code for enum definitions
but not generating code for dictionaries. With future changes to the
IDL generator to expose helpers to convert to and from IDL values
this produced circular depdendencies. To solve this problem, also
generate the dictionary definitions in bindings headers.
Previously, we consulted `cascaded_properties()` in a couple of places
after the cascade pass for the relevant element had finished, forcing
`CascadedProperties` to outlive style resolution.
We now keep the small set of values these consumers need on
`ComputedProperties`. We keep hold of resolved specified values for
properties whose computation depends on inherited info, so they can be
re-resolved when an ancestor changes. We also keep the raw winning
cascaded font-size, as this is needed by the time-traveling monospace
font quirk implemented by `recascade_font_size_if_needed()`.
Previously, presentational hints bypassed the regular cascade pipeline
and wrote directly into `CascadedProperties` under
`CascadeOrigin::Author`. That meant `var()` substitution and the
invalid-at-computed-value-time fallback had to be duplicated in a
separate per-element pass, which in practice missed the IACVT step and
could leave a `GuaranteedInvalidStyleValue` in the cascaded
properties. This caused a crash in downstream code that assumed the
value had been resolved.
This introduces an `AuthorPresentationalHint` cascade origin and feeds
them through the cascade as normal declarations. This means that
`var()` resolution now happens in only one place.
This is preparatory work for routing presentational hints through the
same cascade pipeline as ordinary CSS declarations. Currently those
hints bypass `cascade_declarations()` and write into
`CascadedProperties` directly, which means `var()` substitution has to
be duplicated in a separate pass. To unify them at a single point, we
need to be able to feed an arbitrary property list.
Per "find flattened slotables", a <slot> whose root is a shadow root is
recursed through, not appended to the result. ::slotted() in an outer
shadow must therefore not match such an intermediate slot.
Fixes the gallery on Reddit comment pages: a re-slotted <slot> was
picking up `::slotted(:not([slot])) { display: grid }` from the inner
shadow, which made the <ul> size to its content rather than the flex
container, leaving the carousel's "next" button with a 0px translate.
Share the style cache for shadow roots whose only active author sheet is
the same constructed stylesheet. Matching already carries the effective
shadow root separately, so the cache can be reused while selectors such
as :host and ::slotted() still evaluate against each consuming shadow
root.
Keep the optimization conservative by falling back to the existing
per-scope cache whenever the shadow root has multiple active sheets, a
non-constructed sheet, or a page user stylesheet. Drop the shared cache
when the stylesheet rules or media query match state change.
Add coverage for two shadow roots adopting the same constructed sheet,
including :host, ::slotted(), and replaceSync() invalidation.
Keep cached MatchingRule entries independent from the shadow root that
owns the rule cache. Thread the effective rule shadow root through style
matching as transient state instead, so a rule cache can later be shared
by multiple scopes without copying every cached rule.
This preserves the existing matching behavior by deriving the effective
rule root from each cache lookup site. Pseudo-class invalidation already
operates on a single style scope, so it no longer needs a per-rule scope
filter.
When computing pseudo-element style and no pseudo-element rules match,
StyleComputer was returning early without clearing the cascaded and
custom property data on the AbstractElement. As a result,
getComputedStyle() on the pseudo-element kept exposing values from a
previous matching state.
Clear both before bailing so a transition from matched to unmatched
leaves the pseudo-element in a clean state.
Previously, we were accidentally creating temporary copies of custom
property maps on both sides of a ternary in `compute_style_impl()`. We
now bind to a static empty sentinel instead so the reference binds
directly to `own_values()` without copying.
When inheriting custom-property data from a parent element, we were
copying the parent's full CustomPropertyData regardless of whether
each property was registered with `inherits: false`. That caused
non-inheriting registered properties to leak from the parent,
contrary to the @property spec.
Wrap the parent-side lookup so we strip any custom property whose
registration says it should not inherit, and only build a fresh
CustomPropertyData when at least one property was actually filtered.
Key the filtered view's cache on both the destination document's
identity and its custom-property registration generation. The
generation counter is local to each document, so a subtree adopted
into another document (or queried via getComputedStyle from another
window) could otherwise pick up a cached view computed under an
unrelated registration set and silently skip non-inheriting filtering
in the new document.
A @keyframes rule scoped to a shadow root was not reliably reached
from an animated slotted light-DOM element: the keyframes lookup
walked the element's own root first, then fell back to the document,
but slotted elements can pick up animation-name from a ::slotted(...)
rule that lives in an ancestor shadow root rather than in the
element's own tree.
Track the shadow-root scope that supplied each winning cascaded
declaration, and use that scope to resolve the matching @keyframes
when processing animation definitions. A shared constructable
stylesheet can be adopted into several scopes at once, so the
declaration object alone is too weak as a key; the per-entry
shadow-root pointer disambiguates which adoption actually contributed.
Also refresh running CSS animations' keyframe sets when style is
recomputed. Previously only the first animation creation path set a
keyframe set, so an existing animation never picked up newly inserted
@keyframes rules.
This allows us to avoid the ugly hack in
`property_accepted_type_ranges()`.
This also updates the `ValueType` to be `opacity-value` rather than
`opacity` to match the spec.
Record per-feature :has() invalidation metadata instead of only tracking
whether some selector somewhere mentions a class, id, attribute, tag,
or pseudo-class. The new buckets preserve the relative selector and a
coarse scope classification for each :has() argument, which gives the
next invalidation step enough information to route mutations more
precisely.
Keep this commit behavior-preserving for mutation handling by only
switching the lookup path over to the new metadata buckets. Expose a
test-only counter for the number of candidate :has() metadata entries a
mutation matched, and add coverage showing that one feature can map to
one or multiple :has() buckets without forcing a document-wide yes/no
answer.
sort_matching_rules() was calling Selector::specificity() inside the
sort comparator. MatchingRule already caches the specificity value
at rule insertion time, so use that directly instead.
This were introduced in dfe5d00 but only papered over the underlying
issue that we were computing style for element belonging to detached
documents - this underlying fix was implemented in c173a66 so these
fallbacks/guards are no longer needed
...instead of separate Element and PseudoElement arguments.
As noted, AbstractElement's constness is weird currently, but that's a
tangent I don't want to go on right now.
When a `@keyframes` rule contains `animation-timing-function` with a
`var()`, we cannot eagerly resolve it to an `EasingFunction` at rule
cache build time because there is no element context available. We now
store the unresolved `StyleValue` and defer resolution to
`collect_animation_into()`, where the animated element's custom
properties can be used to substitute the variable. Previously, an
`animation-timing-function` with a `var()` in a `@keyframe` would cause
a crash.
When a shorthand like `background` containing `var()` is used in
a `::selection` rule, the shorthand was filtered out by the pseudo-
element property whitelist before variable resolution could occur.
This left PendingSubstitutionStyleValue longhands unresolved,
causing either a crash or incorrect computed values.
Allow unresolved shorthands to bypass the pseudo-element filter so
variable resolution can proceed. After resolution and expansion
into longhands, filter out any that the pseudo-element does not
support.
Fixes#8625.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This requires us to front load computation of writing-mode and direction
before we encounter any logical aliases or their physical counterparts
so that we can create a mapping context.
Doing this at compute rather than cascade time achieves a few things:
1) Brings us into line with the spec
2) Avoids the double cascade that was previously required to compute
mapping contexts
3) We now compute values of logical aliases, while
`style_value_for_computed_property` maps logical aliases to their
physical counterparts, this didn't account for all cases (i.e. if
there was no layout node, Typed OM, etc).
4) Removes a hurdle to moving other upstream processes (i.e. arbitrary
substitution function resolution, custom property computation) to
compute time as the spec requires.
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>
Per the CSS Animations spec, the animation-timing-function property
describes how the animation progresses between each pair of keyframes,
not as an overall effect-level timing function.
Previously we set it as the effect-level timing function on the
AnimationEffect, which caused easing to be applied to the global
animation progress. This made animations with multiple keyframes
"pause" at the start and end of the full animation cycle instead of
easing smoothly between each pair of keyframes.
Now we:
- Store per-keyframe easing in ResolvedKeyFrame from @keyframes rules
- Store the default easing on CSSAnimation instead of on the effect
- Apply per-keyframe easing to the interval progress during
interpolation, falling back to the CSS animation's default easing
- Also store per-keyframe easing from JS-created KeyframeEffects to
avoid incorrectly applying CSS default easing to replaced effects
When processing CSS animations, we were only looking up @keyframes
rules from the document-level rule cache, passing nullptr for the
shadow root parameter. This meant that @keyframes defined inside
shadow DOM <style> elements were never found, and animations
referencing them would silently have no keyframes.
Fix this by first checking the element's containing shadow root for
@keyframes rules, then falling back to the document-level rules.
Per CSS2 section 9.7, if position has the value absolute or fixed,
the computed value of float is none. We were already blockifying the
display for such elements, but not resetting the computed value of
float. This made the wrong value observable via getComputedStyle().
The :host::part() pattern allows a shadow DOM's own stylesheet to
style its internal elements that have been exposed via the part
attribute. Previously, ::part() rules were only collected from
ancestor shadow roots (for external part styling), but never from the
element's own containing shadow root.
Fix this by also collecting ::part() rules from the element's own
shadow root in collect_matching_rules(). Additionally, fix the
selector engine's ::part() compound matching to preserve the
shadow_host when the rule originates from the part element's own
shadow root, allowing :host to match correctly in the same compound
selector.
This fixes 2 previously failing WPT tests:
- css/css-shadow-parts/host-part-002.html
- css/css-shadow-parts/host-part-nesting.html
When an element inside a shadow DOM is itself a shadow host, and a
rule from the parent shadow DOM uses a selector like
`:host([attr]) .child`, the combinator traversal needs to reach the
outer shadow host to match `:host([attr])`.
Previously, when the styled element was a shadow host and the rule
came from outside its own shadow root, we set shadow_host_to_use to
nullptr. This caused traverse_up() to use parent() which cannot
cross the shadow boundary, preventing the selector from reaching the
outer :host.
Fix this by using the rule's shadow root's host as the traversal
boundary instead of nullptr. This allows the descendant combinator
to traverse from the element up through the enclosing shadow DOM to
reach the outer shadow host for :host() matching.
