Remove this trait and replace it by two non-public functions on
ServoThreadSafeLayoutNode. This requires making the iterator not
generic, which simplifies things a little bit as well.
There are duplicate sets of Layout DOM wrappers: one for Layout 2013 and
one for Layout 2020. As part of cleaning up and simplifying the
wrappers, this change parameterizes them on the specific layout data
they contain. This allows them to be shared again. In addition, various
small cleanups are included.
Fixes#29691.
During layout it is often useful, for various specification reasons, to
know if an element is the `<body>` element of an `<html>` element root. There
are a couple places where a brittle heuristic is used to detect `<body>`
elements. This information is going to be even more important to
properly handle `<html>` elements that inherit their overflow property from
their `<body>` children.
Implementing this properly requires updating the DOM wrapper interface.
This check does reach up to the parent of thread-safe nodes, but this is
essentially the same kind of operation that `parent_style()` does, so is
ostensibly safe.
This change should not change any behavior and is just a preparation
step for properly handle `<body>` overflow.
This allows servo to use the ExternalScrollId API from WebRender fixing
some issues related to duplicate scroll root ids.
Fixes#17176.
Fixes#19287.
Fixes#19648.
Now that we have an Element around on cascade, we can stop using the cascade
flags mechanism to pass various element-related state, like "is this element the
root", or "should it use the item-based display fixup".
That fixes handwaviness in the handling of those flags from style reparenting,
and code duplication to handle tricky stuff like :visited.
There are a number of other changes that are worth noticing:
* skip_root_and_item_based_display_fixup is renamed to skip_item_display_fixup:
TElement::is_root() already implies being the document element, which by
definition is not native anonymous and not a pseudo-element.
Thus, you never get fixed-up if your NAC or a pseudo, which is what the code
tried to avoid, so the only fixup with a point is the item one, which is
necessary.
* The pseudo-element probing code was refactored to return early a
Option::<CascadeInputs>::None, which is nicer than what it was doing.
* The visited_links_enabled check has moved to selector-matching time. The rest
of the checks aren't based on whether the element is a link, or are properly
guarded by parent_style.visited_style().is_some() or visited_rules.is_some().
Thus you can transitively infer that no element will end up with a :visited
style, not even from style reparenting.
Anyway, the underlying reason why I want the element in StyleAdjuster is because
we're going to implement an adjustment in there depending on the tag of the
element (converting display: contents to display: none depending on the tag), so
computing that information eagerly, including a hash lookup, wouldn't be nice.
Not super-proud of this one, but it's the easiest way I could think of.
The changeset looks bigger than what it is, because while at it I've rewrapped a
fair amount of functions around to use proper block indentation.
Alternatives are parameterizing Stylist by <E>, which is not fun, or moving the
concrete element from layout_thread to layout, but that implies layout depending
on script, which isn't fun either.
Other alternative is implementing an empty enum and making anon boxes work on
it. It has the advantage of removing the annoying type parameter, but the
disadvantage of instantiating `cascade` twice, which isn't great, and having to
maintain all the boilerplate of a `TElement` implementation that just does
nothing.
We only override it when there's no "open" attribute. But a display: none
pseudo-element is the same as no pseudo-element at all.
This should get the same behavior when iterating children in dom_wrapper.rs
All TElement's implement Copy, and are just pointers, so the double indirection
is stupid.
I'm going to try to see if removing this double-indirection fixes some
selector-matching performance, and this is a trivial pre-requisite while I wait
for Talos results.
The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
