ladybird/Libraries/LibWeb/HTML/HTMLMarqueeElement.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

116 lines
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C++

/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2024, Jamie Mansfield <jmansfield@cadixdev.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Bindings/HTMLMarqueeElementPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/StyleValues/CSSColorValue.h>
#include <LibWeb/HTML/HTMLMarqueeElement.h>
#include <LibWeb/HTML/Numbers.h>
#include <LibWeb/HTML/Parser/HTMLParser.h>
namespace Web::HTML {
GC_DEFINE_ALLOCATOR(HTMLMarqueeElement);
HTMLMarqueeElement::HTMLMarqueeElement(DOM::Document& document, DOM::QualifiedName qualified_name)
: HTMLElement(document, move(qualified_name))
{
}
HTMLMarqueeElement::~HTMLMarqueeElement() = default;
void HTMLMarqueeElement::initialize(JS::Realm& realm)
{
Base::initialize(realm);
WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLMarqueeElement);
}
bool HTMLMarqueeElement::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::height,
HTML::AttributeNames::hspace,
HTML::AttributeNames::vspace,
HTML::AttributeNames::width);
}
void HTMLMarqueeElement::apply_presentational_hints(GC::Ref<CSS::CascadedProperties> cascaded_properties) const
{
HTMLElement::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#the-marquee-element-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::height) {
// https://html.spec.whatwg.org/multipage/rendering.html#the-marquee-element-2:maps-to-the-dimension-property
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::hspace) {
if (auto parsed_value = parse_dimension_value(value)) {
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::MarginLeft, *parsed_value);
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::MarginRight, *parsed_value);
}
} else if (name == HTML::AttributeNames::vspace) {
if (auto parsed_value = parse_dimension_value(value)) {
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::MarginTop, *parsed_value);
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::MarginBottom, *parsed_value);
}
} else 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);
}
}
});
}
// https://html.spec.whatwg.org/multipage/obsolete.html#dom-marquee-scrollamount
WebIDL::UnsignedLong HTMLMarqueeElement::scroll_amount()
{
// The scrollAmount IDL attribute must reflect the scrollamount content attribute. The default value is 6.
if (auto scroll_amount_string = get_attribute(HTML::AttributeNames::scrollamount); scroll_amount_string.has_value()) {
if (auto scroll_amount = parse_non_negative_integer(*scroll_amount_string); scroll_amount.has_value() && *scroll_amount <= 2147483647)
return *scroll_amount;
}
return 6;
}
// https://html.spec.whatwg.org/multipage/obsolete.html#dom-marquee-scrollamount
WebIDL::ExceptionOr<void> HTMLMarqueeElement::set_scroll_amount(WebIDL::UnsignedLong value)
{
if (value > 2147483647)
value = 6;
return set_attribute(HTML::AttributeNames::scrollamount, String::number(value));
}
// https://html.spec.whatwg.org/multipage/obsolete.html#dom-marquee-scrolldelay
WebIDL::UnsignedLong HTMLMarqueeElement::scroll_delay()
{
// The scrollDelay IDL attribute must reflect the scrolldelay content attribute. The default value is 85.
if (auto scroll_delay_string = get_attribute(HTML::AttributeNames::scrolldelay); scroll_delay_string.has_value()) {
if (auto scroll_delay = parse_non_negative_integer(*scroll_delay_string); scroll_delay.has_value() && *scroll_delay <= 2147483647)
return *scroll_delay;
}
return 85;
}
// https://html.spec.whatwg.org/multipage/obsolete.html#dom-marquee-scrolldelay
WebIDL::ExceptionOr<void> HTMLMarqueeElement::set_scroll_delay(WebIDL::UnsignedLong value)
{
if (value > 2147483647)
value = 85;
return set_attribute(HTML::AttributeNames::scrolldelay, String::number(value));
}
}