ladybird/Libraries/LibWeb/HTML/HTMLTableSectionElement.cpp
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

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/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2022, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Bindings/HTMLTableSectionElementPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/StyleValues/CSSColorValue.h>
#include <LibWeb/CSS/StyleValues/ImageStyleValue.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/ElementFactory.h>
#include <LibWeb/DOM/HTMLCollection.h>
#include <LibWeb/HTML/HTMLTableRowElement.h>
#include <LibWeb/HTML/HTMLTableSectionElement.h>
#include <LibWeb/HTML/Parser/HTMLParser.h>
#include <LibWeb/Namespace.h>
namespace Web::HTML {
GC_DEFINE_ALLOCATOR(HTMLTableSectionElement);
HTMLTableSectionElement::HTMLTableSectionElement(DOM::Document& document, DOM::QualifiedName qualified_name)
: HTMLElement(document, move(qualified_name))
{
}
HTMLTableSectionElement::~HTMLTableSectionElement() = default;
void HTMLTableSectionElement::initialize(JS::Realm& realm)
{
Base::initialize(realm);
WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLTableSectionElement);
}
void HTMLTableSectionElement::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_rows);
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tbody-rows
GC::Ref<DOM::HTMLCollection> HTMLTableSectionElement::rows() const
{
// The rows attribute must return an HTMLCollection rooted at this element,
// whose filter matches only tr elements that are children of this element.
if (!m_rows) {
m_rows = DOM::HTMLCollection::create(const_cast<HTMLTableSectionElement&>(*this), DOM::HTMLCollection::Scope::Children, [](Element const& element) {
return is<HTMLTableRowElement>(element);
});
}
return *m_rows;
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tbody-insertrow
WebIDL::ExceptionOr<GC::Ref<HTMLTableRowElement>> HTMLTableSectionElement::insert_row(WebIDL::Long index)
{
auto rows_collection = rows();
auto rows_collection_size = static_cast<long>(rows_collection->length());
// 1. If index is less than 1 or greater than the number of elements in the rows collection, throw an "IndexSizeError" DOMException.
if (index < -1 || index > rows_collection_size)
return WebIDL::IndexSizeError::create(realm(), "Index is negative or greater than the number of rows"_string);
// 2. Let table row be the result of creating an element given this element's node document, "tr", and the HTML namespace.
auto& table_row = static_cast<HTMLTableRowElement&>(*TRY(DOM::create_element(document(), TagNames::tr, Namespace::HTML)));
// 3. If index is 1 or equal to the number of items in the rows collection, then append table row to this element.
if (index == -1 || index == rows_collection_size)
TRY(append_child(table_row));
// 4. Otherwise, insert table row as a child of this element, immediately before the index-th tr element in the rows collection.
else
insert_before(table_row, rows_collection->item(index));
// 5. Return table row.
return GC::Ref(table_row);
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tbody-deleterow
WebIDL::ExceptionOr<void> HTMLTableSectionElement::delete_row(WebIDL::Long index)
{
auto rows_collection = rows();
auto rows_collection_size = static_cast<long>(rows_collection->length());
// 1. If index is less than 1 or greater than or equal to the number of elements in the rows collection, then throw an "IndexSizeError" DOMException.
if (index < -1 || index >= rows_collection_size)
return WebIDL::IndexSizeError::create(realm(), "Index is negative or greater than or equal to the number of rows"_string);
// 2. If index is 1, then remove the last element in the rows collection from this element, or do nothing if the rows collection is empty.
if (index == -1) {
if (rows_collection_size > 0)
rows_collection->item(rows_collection_size - 1)->remove();
}
// 3. Otherwise, remove the indexth element in the rows collection from this element.
else {
rows_collection->item(index)->remove();
}
return {};
}
bool HTMLTableSectionElement::is_presentational_hint(FlyString const& name) const
{
if (Base::is_presentational_hint(name))
return true;
return first_is_one_of(name,
HTML::AttributeNames::background,
HTML::AttributeNames::bgcolor);
}
void HTMLTableSectionElement::apply_presentational_hints(GC::Ref<CSS::CascadedProperties> cascaded_properties) const
{
for_each_attribute([&](auto& name, auto& value) {
// https://html.spec.whatwg.org/multipage/rendering.html#tables-2:encoding-parsing-and-serializing-a-url
if (name == HTML::AttributeNames::background) {
if (auto parsed_value = document().encoding_parse_url(value); parsed_value.is_valid())
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BackgroundImage, CSS::ImageStyleValue::create(parsed_value));
}
// https://html.spec.whatwg.org/multipage/rendering.html#tables-2:rules-for-parsing-a-legacy-colour-value
else if (name == HTML::AttributeNames::bgcolor) {
if (auto color = parse_legacy_color_value(value); color.has_value())
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BackgroundColor, CSS::CSSColorValue::create_from_color(color.value()));
}
});
}
}