ladybird/Libraries/LibWeb/HTML/HTMLTableColElement.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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2.5 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Bindings/HTMLTableColElementPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/HTML/HTMLTableColElement.h>
#include <LibWeb/HTML/Numbers.h>
#include <LibWeb/HTML/Parser/HTMLParser.h>
namespace Web::HTML {
GC_DEFINE_ALLOCATOR(HTMLTableColElement);
HTMLTableColElement::HTMLTableColElement(DOM::Document& document, DOM::QualifiedName qualified_name)
: HTMLElement(document, move(qualified_name))
{
}
HTMLTableColElement::~HTMLTableColElement() = default;
void HTMLTableColElement::initialize(JS::Realm& realm)
{
Base::initialize(realm);
WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLTableColElement);
}
// https://html.spec.whatwg.org/multipage/tables.html#dom-colgroup-span
WebIDL::UnsignedLong HTMLTableColElement::span() const
{
// The span IDL attribute must reflect the content attribute of the same name. It is clamped to the range [1, 1000], and its default value is 1.
if (auto span_string = get_attribute(HTML::AttributeNames::span); span_string.has_value()) {
if (auto span_digits = parse_non_negative_integer_digits(*span_string); span_digits.has_value()) {
auto span = AK::StringUtils::convert_to_int<i64>(*span_digits);
// NOTE: If span has no value at this point, the value must be larger than NumericLimits<i64>::max(), so return the maximum value of 1000.
if (!span.has_value())
return 1000;
return clamp(*span, 1, 1000);
}
}
return 1;
}
WebIDL::ExceptionOr<void> HTMLTableColElement::set_span(unsigned int value)
{
if (value > 2147483647)
value = 1;
return set_attribute(HTML::AttributeNames::span, String::number(value));
}
bool HTMLTableColElement::is_presentational_hint(FlyString const& name) const
{
if (Base::is_presentational_hint(name))
return true;
return name == HTML::AttributeNames::width;
}
void HTMLTableColElement::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:maps-to-the-dimension-property-2
if (name == HTML::AttributeNames::width) {
if (auto parsed_value = parse_dimension_value(value)) {
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::Width, *parsed_value);
}
}
});
}
}