Move ComputedProperties and CascadedProperties out of the GC. They no
longer contain strong references to GC-managed data.
Keep computed styles alive from DOM elements and animation updates with
RefPtr. Pass style into layout constructors by reference, since layout
only copies the values it needs while building nodes.
Use GC::Weak for cascade source links, so entries no longer keep the
style declaration or shadow root alive.
Collect the style rules that apply to an inspected element and expose
them through the existing DOM node inspection path. This gives Firefox's
Rules panel real rule forms instead of the previous empty getApplied
response.
Apply author declarations in encapsulation-context order before layer,
specificity, scope proximity, and source-order tie breaking. Normal
author rules now cascade from inner shadow contexts outward. This lets
outer contexts override component defaults. Important author rules
cascade the other way so inner contexts can enforce requirements.
Keep the ordering context-bucketed. The common document-only path still
collects and sorts one author context. Custom properties follow the same
context order. var() substitution now observes the same winners as
longhand properties.
Make revert-layer remove declarations only from the matching cascade
origin, context, and layer. This keeps presentational hints and values
from other shadow contexts available when one context rolls back its own
layer.
Add coverage for document and shadow-host competition, slotted rules,
nested slot contexts, inline styles, important declarations, custom
properties, and revert-layer across shadow contexts.
Keep the temporary scoped matching rule list on StyleComputer.
This lets repeated style matching reuse its allocation instead of
creating a large stack object in collect_matching_rules().
Release builds zero that stack object before the constructor runs due
to automatic variable initialization. This was causing a 16 KiB memset
on every call to this function(!)
Verify that the scratch vector is empty on entry so accidental reentry
is caught before it can corrupt the outer rule collection.
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()`.
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.
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.
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.
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.
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.
Replace flat InvalidationSet with recursive InvalidationPlan trees
that preserve selector combinator structure. Previously, selectors
with sibling combinators (+ and ~) fell back to whole-subtree
invalidation. Now the StyleInvalidator walks the DOM following
combinator-specific rules, so ".a + .b" only invalidates the
adjacent sibling matching ".b" rather than the entire subtree.
Plans are compiled at stylesheet parse time by walking selector
compounds right-to-left. For ".a .b + .c":
```
[.c]: plan = { invalidate_self }
register: "c" → plan
[.b]: wrap("+", righthand)
plan = { sibling_rules: [match ".c", adjacent, {self}] }
register: "b" → plan
[.a]: wrap(" ", righthand)
plan = { descendant_rules: [match ".b", <sibling plan>] }
register: "a" → plan
```
Changing class "a" produces a plan that walks descendants for ".b",
checks ".b"'s adjacent sibling for ".c", and invalidates only that
element.
Previously we didn't clear the computation context caches after:
- Recomputing inherited style
- Computing keyframe values
We now clear the caches in those two cases and verify it has been
cleared before using it.
Fixes#7959
Previously we computed font properties separately from other properties
for two reasons:
1) These font properties were computed using a different length
resolution context than the rest of the properties.
2) These properties were required to be computed before creating the
length resolution context for the rest of the properties.
The first issue was solved in the previous commit by introducing a
generic method to get the computation context for a property, and
the second is solved in this commit by computing properties in the
required order.
This simplifies the code a bit and opens up some opportunities for
optimization.
The computation context used is the main thing distinguishing the
computation of font/non-font properties so having a generic method to
handle this will allow us to consolidate logic between the two.
The main change here is that we now properly absolutize values which
means we now support `random()` and `sibling-{count,index}()`
We are also more consistent with how we handle computation for the other
font properties
The `:has()` pseudo-class requires traversing descendants (or siblings)
to find matches.
With this change we cache results keyed by `(Selector*, Element*)`
pairs. The cache is stored in `StyleComputer` and cleared at the start
of each style computation pass in `Document::update_style()`.
When `:has()` uses a descendant combinator and we find a match, we also
cache that all ancestors between the matching descendant and the
anchor match. For example with `div:has(.target)`:
```html
<div id="A"> <!-- checking :has(.target) here -->
<div id="B">
<div id="C">
<span class="target"/>
</div>
</div>
</div>
```
When we find `.target` while checking `div#A`, we also cache that
`div#B` and `div#C` match `:has(.target)` since they also contain
`.target`. Later when styling these elements, we get cache hits and skip
traversal.
...when the style is `none` or `hidden`. `outline-width` is not affected
by `outline-style: none` at all.
In our codebase, that means doing the border-width conversion when
assigning to ComputedValues.
Corresponds to:
2a3d1e4d1009f11f2ef9
Font computation and loading is distinct enough from style computation
that it makes more sense to have this in it's own class.
This will be useful later when we move the font loading process to
`ComputedProperties` in order to respect animated values.
Since we resolve any relative lengths at compute time there's no need
for the value to be passed around as a `NumberOrCalculated` and we can
just resolve it within `ComputedProperties::font_variation_settings`.
The only place this is used it is used with value_or so there's no need
to return it is an `Optional`.
This is only used for loading fonts (which occurs during style
computation) so there's no need to store it in `ComputedValues`
Before this change, we've been maintaining various StyleComputer caches
at the document level.
This made sense for old-school documents without shadow trees, since
all the style information was document-wide anyway. However, documents
with many shadow trees ended up suffering since any time you mutated
a style sheet inside a shadow tree, *all* style caches for the entire
document would get invalidated.
This was particularly expensive on Reddit, which has tons of shadow
trees with their own style elements. Every time we'd create one of their
custom elements, we'd invalidate the document-level "rule cache" and
have to rebuild it, taking about ~60ms each time (ouch).
This commit introduces a new object called StyleScope.
Every Document and ShadowRoot has its own StyleScope. Rule caches etc
are moved from StyleComputer to StyleScope.
Rule cache invalidation now happens at StyleScope level. As an example,
rule cache rebuilds now take ~1ms on Reddit instead of ~60ms.
This is largely a mechanical change, moving things around, but there's
one key detail to be aware of: due to the :host selector, which works
across the shadow DOM boundary and reaches from inside a shadow tree out
into the light tree, there are various places where we have to check
both the shadow tree's StyleScope *and* the document-level StyleScope
in order to get all rules that may apply.
The majority of time in `compute_font()` was spent in
`font_matching_algorithm()` repeatedly computing the same values. We
now cache these values to avoid unnecessary work.
Makes the `compute_font_variation_settings` function match other
`compute_font_*` by absolutizing values passed into them. It resolves a
crash related to using `siblings-count` inside `font-variation-settings`
Co-authored-by: Sam Atkins <sam@ladybird.org>
Integrates the new `FontVariationSettings` from LibGfx into LibWeb to
enable initial variable font functionality. Currently, only the `wght`
(weight) axis is fully supported and tested. This update also introduces
support for the CSS `font-variation-settings` property.
Since we now have access to the `AbstractElement` through the
`ComputationContext` we can just set the flag that this element relies
on tree counting functions directly, no need to pass this struct around.
Tree counting functions should be resolved at style computation time -
to do this we will need to know the element's sibling count and index.
This commit computes that information and propagates it to the various
`StyleValue::to_computed_value` methods.
This struct will in the future hold information other than a length
resolution context (e.g. context for tree counting functions) and a
single struct is easier to work with than multiple parameters.
We now fail a few more tests in properties-value-inherit-001.txt as we
no longer overwrite the non-animated value of `line-height` with the
animated value, this is in line with other major browsers.
We now also more closely follow the spec when computing values for
font-weight and we now:
- Support relative lengths in `calc()`s
- Properly clamp `calc()`s
- Support relative keywords (e.g. lighter, bolder)
- Respect that font-weight can be a non-integer number.
This does expose a few false positives in the font-weight-computed.html
WPT test. This is because we don't recompute non-inherited font-weight
within `recompute_inherited_style` which means that relative keyword
values can fall out of sync with their parent's value. These previously
passed as we treated `bolder` and `lighter` as aliases for `bold` and
`normal` respectively.
