ladybird/Libraries/LibWeb/HTML/HTMLTableRowElement.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) 2020-2022, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Bindings/HTMLTableRowElementPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/Parser/Parser.h>
#include <LibWeb/CSS/Parser/ParsingContext.h>
#include <LibWeb/CSS/StyleValues/CSSColorValue.h>
#include <LibWeb/CSS/StyleValues/CSSKeywordValue.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/HTMLTableCellElement.h>
#include <LibWeb/HTML/HTMLTableElement.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(HTMLTableRowElement);
HTMLTableRowElement::HTMLTableRowElement(DOM::Document& document, DOM::QualifiedName qualified_name)
: HTMLElement(document, move(qualified_name))
{
}
HTMLTableRowElement::~HTMLTableRowElement() = default;
void HTMLTableRowElement::initialize(JS::Realm& realm)
{
Base::initialize(realm);
WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLTableRowElement);
}
bool HTMLTableRowElement::is_presentational_hint(FlyString const& name) const
{
if (Base::is_presentational_hint(name))
return true;
return first_is_one_of(name,
HTML::AttributeNames::bgcolor,
HTML::AttributeNames::background,
HTML::AttributeNames::height,
HTML::AttributeNames::valign);
}
void HTMLTableRowElement::apply_presentational_hints(GC::Ref<CSS::CascadedProperties> cascaded_properties) const
{
Base::apply_presentational_hints(cascaded_properties);
for_each_attribute([&](auto& name, auto& value) {
if (name == HTML::AttributeNames::bgcolor) {
// https://html.spec.whatwg.org/multipage/rendering.html#tables-2:rules-for-parsing-a-legacy-colour-value
auto color = parse_legacy_color_value(value);
if (color.has_value())
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BackgroundColor, CSS::CSSColorValue::create_from_color(color.value()));
} else if (name == HTML::AttributeNames::background) {
// https://html.spec.whatwg.org/multipage/rendering.html#tables-2:encoding-parsing-and-serializing-a-url
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));
} else if (name == HTML::AttributeNames::height) {
if (auto parsed_value = parse_dimension_value(value))
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::Height, *parsed_value);
} else if (name == HTML::AttributeNames::valign) {
if (auto parsed_value = parse_css_value(CSS::Parser::ParsingContext { document() }, value, CSS::PropertyID::VerticalAlign))
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::VerticalAlign, parsed_value.release_nonnull());
}
});
}
void HTMLTableRowElement::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_cells);
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tr-cells
GC::Ref<DOM::HTMLCollection> HTMLTableRowElement::cells() const
{
// The cells attribute must return an HTMLCollection rooted at this tr element,
// whose filter matches only td and th elements that are children of the tr element.
if (!m_cells) {
m_cells = DOM::HTMLCollection::create(const_cast<HTMLTableRowElement&>(*this), DOM::HTMLCollection::Scope::Children, [](Element const& element) {
return is<HTMLTableCellElement>(element);
});
}
return *m_cells;
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tr-rowindex
int HTMLTableRowElement::row_index() const
{
// The rowIndex attribute must, if this element has a parent table element,
// or a parent tbody, thead, or tfoot element and a grandparent table element,
// return the index of this tr element in that table element's rows collection.
// If there is no such table element, then the attribute must return 1.
auto rows_collection = [&]() -> GC::Ptr<DOM::HTMLCollection> {
if (!parent())
return nullptr;
if (is<HTMLTableElement>(*parent()))
return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent())).rows();
if (is<HTMLTableSectionElement>(*parent()) && parent()->parent() && is<HTMLTableElement>(*parent()->parent()))
return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent()->parent())).rows();
return nullptr;
}();
if (!rows_collection)
return -1;
auto rows = rows_collection->collect_matching_elements();
for (size_t i = 0; i < rows.size(); ++i) {
if (rows[i] == this)
return i;
}
return -1;
}
int HTMLTableRowElement::section_row_index() const
{
// The sectionRowIndex attribute must, if this element has a parent table, tbody, thead, or tfoot element,
// return the index of the tr element in the parent element's rows collection
// (for tables, that's HTMLTableElement's rows collection; for table sections, that's HTMLTableSectionElement's rows collection).
// If there is no such parent element, then the attribute must return 1.
auto rows_collection = [&]() -> GC::Ptr<DOM::HTMLCollection> {
if (!parent())
return nullptr;
if (is<HTMLTableElement>(*parent()))
return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent())).rows();
if (is<HTMLTableSectionElement>(*parent()))
return static_cast<HTMLTableSectionElement const&>(*parent()).rows();
return nullptr;
}();
if (!rows_collection)
return -1;
auto rows = rows_collection->collect_matching_elements();
for (size_t i = 0; i < rows.size(); ++i) {
if (rows[i] == this)
return i;
}
return -1;
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tr-insertcell
WebIDL::ExceptionOr<GC::Ref<HTMLTableCellElement>> HTMLTableRowElement::insert_cell(i32 index)
{
auto cells_collection = cells();
auto cells_collection_size = static_cast<i32>(cells_collection->length());
// 1. If index is less than 1 or greater than the number of elements in the cells collection, then throw an "IndexSizeError" DOMException.
if (index < -1 || index > cells_collection_size)
return WebIDL::IndexSizeError::create(realm(), "Index is negative or greater than the number of cells"_string);
// 2. Let table cell be the result of creating an element given this tr element's node document, "td", and the HTML namespace.
auto& table_cell = static_cast<HTMLTableCellElement&>(*TRY(DOM::create_element(document(), HTML::TagNames::td, Namespace::HTML)));
// 3. If index is equal to 1 or equal to the number of items in cells collection, then append table cell to this tr element.
if (index == -1 || index == cells_collection_size)
TRY(append_child(table_cell));
// 4. Otherwise, insert table cell as a child of this tr element, immediately before the indexth td or th element in the cells collection.
else
insert_before(table_cell, cells_collection->item(index));
// 5. Return table cell.
return GC::Ref(table_cell);
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-tr-deletecell
WebIDL::ExceptionOr<void> HTMLTableRowElement::delete_cell(i32 index)
{
auto cells_collection = cells();
auto cells_collection_size = static_cast<i32>(cells_collection->length());
// 1. If index is less than 1 or greater than or equal to the number of elements in the cells collection, then throw an "IndexSizeError" DOMException.
if (index < -1 || index >= cells_collection_size)
return WebIDL::IndexSizeError::create(realm(), "Index is negative or greater than or equal to the number of cells"_string);
// 2. If index is 1, then remove the last element in the cells collection from its parent, or do nothing if the cells collection is empty.
if (index == -1) {
if (cells_collection_size > 0)
cells_collection->item(cells_collection_size - 1)->remove();
}
// 3. Otherwise, remove the indexth element in the cells collection from its parent.
else {
cells_collection->item(index)->remove();
}
return {};
}
}