ladybird/Libraries/LibWeb/HTML/HTMLBodyElement.h
Andreas Kling b981e6f7bc LibWeb: Avoid many style invalidations on DOM attribute mutation
Many times, attribute mutation doesn't necessitate a full style
invalidation on the element. However, the conditions are pretty
elaborate, so this first version has a lot of false positives.

We only need to invalidate style when any of these things apply:

1. The change may affect the match state of a selector somewhere.
2. The change may affect presentational hints applied to the element.

For (1) in this first version, we have a fixed list of attribute names
that may affect selectors. We also collect all names referenced by
attribute selectors anywhere in the document.

For (2), we add a new Element::is_presentational_hint() virtual that
tells us whether a given attribute name is a presentational hint.

This drastically reduces style work on many websites. As an example,
https://cnn.com/ is once again browseable.
2024-12-24 17:17:09 +01:00

55 lines
1.7 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibWeb/ARIA/Roles.h>
#include <LibWeb/HTML/HTMLElement.h>
#include <LibWeb/HTML/WindowEventHandlers.h>
namespace Web::HTML {
class HTMLBodyElement final
: public HTMLElement
, public WindowEventHandlers {
WEB_PLATFORM_OBJECT(HTMLBodyElement, HTMLElement);
GC_DECLARE_ALLOCATOR(HTMLBodyElement);
public:
virtual ~HTMLBodyElement() override;
virtual void attribute_changed(FlyString const& name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_) override;
virtual bool is_presentational_hint(FlyString const&) const override;
virtual void apply_presentational_hints(GC::Ref<CSS::CascadedProperties>) const override;
// https://www.w3.org/TR/html-aria/#el-body
virtual Optional<ARIA::Role> default_role() const override { return ARIA::Role::generic; }
private:
HTMLBodyElement(DOM::Document&, DOM::QualifiedName);
virtual void visit_edges(Visitor&) override;
// ^DOM::Node
virtual bool is_html_body_element() const override { return true; }
virtual void initialize(JS::Realm&) override;
// ^HTML::GlobalEventHandlers
virtual GC::Ptr<DOM::EventTarget> global_event_handlers_to_event_target(FlyString const& event_name) override;
// ^HTML::WindowEventHandlers
virtual GC::Ptr<DOM::EventTarget> window_event_handlers_to_event_target() override;
RefPtr<CSS::ImageStyleValue> m_background_style_value;
};
}
namespace Web::DOM {
template<>
inline bool Node::fast_is<HTML::HTMLBodyElement>() const { return is_html_body_element(); }
}