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LibWeb: Implement "directionality" of an Element

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Sam Atkins 2023-08-21 11:47:24 +01:00 committed by Andreas Kling
parent 9f83c0f0da
commit 9522f761a3
Notes: sideshowbarker 2024-07-17 18:38:54 +09:00 
Author: https://github.com/AtkinsSJ
Commit: https://github.com/SerenityOS/serenity/commit/9522f761a3
Pull-request: https://github.com/SerenityOS/serenity/pull/20593
Reviewed-by: https://github.com/awesomekling
2 changed files with 164 additions and 0 deletions
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150
Userland/Libraries/LibWeb/DOM/Element.cpp
View File

@ -1,5 +1,6 @@
/*
* Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022-2023, San Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -7,6 +8,8 @@
#include <AK/AnyOf.h>
#include <AK/Debug.h>
#include <AK/StringBuilder.h>
#include <LibUnicode/CharacterTypes.h>
#include <LibUnicode/UnicodeData.h>
#include <LibWeb/Bindings/ElementPrototype.h>
#include <LibWeb/Bindings/ExceptionOrUtils.h>
#include <LibWeb/Bindings/MainThreadVM.h>
@ -42,6 +45,7 @@
#include <LibWeb/HTML/HTMLOptGroupElement.h>
#include <LibWeb/HTML/HTMLOptionElement.h>
#include <LibWeb/HTML/HTMLSelectElement.h>
#include <LibWeb/HTML/HTMLStyleElement.h>
#include <LibWeb/HTML/HTMLTextAreaElement.h>
#include <LibWeb/HTML/Parser/HTMLParser.h>
#include <LibWeb/HTML/Window.h>
@ -391,6 +395,16 @@ void Element::attribute_changed(DeprecatedFlyString const& name, DeprecatedStrin
m_inline_style = parse_css_style_attribute(CSS::Parser::ParsingContext(document()), value, *this);
set_needs_style_update(true);
}
} else if (name == HTML::AttributeNames::dir) {
// https://html.spec.whatwg.org/multipage/dom.html#attr-dir
if (value.equals_ignoring_ascii_case("ltr"sv))
m_dir = Dir::Ltr;
else if (value.equals_ignoring_ascii_case("rtl"sv))
m_dir = Dir::Rtl;
else if (value.equals_ignoring_ascii_case("auto"sv))
m_dir = Dir::Auto;
else
m_dir = {};
}
}
@ -1833,4 +1847,140 @@ IntersectionObserver::IntersectionObserverRegistration& Element::get_intersectio
return *registration_iterator;
}
// https://html.spec.whatwg.org/multipage/dom.html#the-directionality
Element::Directionality Element::directionality() const
{
// The directionality of an element (any element, not just an HTML element) is either 'ltr' or 'rtl',
// and is determined as per the first appropriate set of steps from the following list:
auto dir = this->dir();
// -> If the element's dir attribute is in the ltr state
// -> If the element is a document element and the dir attribute is not in a defined state
// (i.e. it is not present or has an invalid value)
// -> If the element is an input element whose type attribute is in the Telephone state, and the
// dir attribute is not in a defined state (i.e. it is not present or has an invalid value)
if (dir == Dir::Ltr
|| (is_document_element() && !dir.has_value())
|| (is<HTML::HTMLInputElement>(this)
&& static_cast<HTML::HTMLInputElement const&>(*this).type_state() == HTML::HTMLInputElement::TypeAttributeState::Telephone
&& !dir.has_value())) {
// The directionality of the element is 'ltr'.
return Directionality::Ltr;
}
// -> If the element's dir attribute is in the rtl state
if (dir == Dir::Rtl) {
// The directionality of the element is 'rtl'.
return Directionality::Rtl;
}
// -> If the element is an input element whose type attribute is in the Text, Search, Telephone,
// URL, or Email state, and the dir attribute is in the auto state
// -> If the element is a textarea element and the dir attribute is in the auto state
if ((is<HTML::HTMLInputElement>(this)
&& first_is_one_of(static_cast<HTML::HTMLInputElement const&>(*this).type_state(),
HTML::HTMLInputElement::TypeAttributeState::Text, HTML::HTMLInputElement::TypeAttributeState::Search,
HTML::HTMLInputElement::TypeAttributeState::Telephone, HTML::HTMLInputElement::TypeAttributeState::URL,
HTML::HTMLInputElement::TypeAttributeState::Email)
&& dir == Dir::Auto)
|| (is<HTML::HTMLTextAreaElement>(this) && dir == Dir::Auto)) {
auto value = is<HTML::HTMLInputElement>(this)
? static_cast<HTML::HTMLInputElement const&>(*this).value()
: static_cast<HTML::HTMLTextAreaElement const&>(*this).value();
// If the element's value contains a character of bidirectional character type AL or R, and
// there is no character of bidirectional character type L anywhere before it in the element's
// value, then the directionality of the element is 'rtl'. [BIDI]
for (auto code_point : Utf8View(value)) {
auto bidi_class = Unicode::bidirectional_class(code_point);
if (bidi_class == Unicode::BidirectionalClass::L)
break;
if (bidi_class == Unicode::BidirectionalClass::AL || bidi_class == Unicode::BidirectionalClass::R)
return Directionality::Rtl;
}
// Otherwise, if the element's value is not the empty string, or if the element is a document element,
// the directionality of the element is 'ltr'.
if (!value.is_empty() || is_document_element()) {
return Directionality::Ltr;
}
// Otherwise, the directionality of the element is the same as the element's parent element's directionality.
else {
return parent_element()->directionality();
}
}
// -> If the element's dir attribute is in the auto state
// FIXME: -> If the element is a bdi element and the dir attribute is not in a defined state
// (i.e. it is not present or has an invalid value)
if (dir == Dir::Auto) {
// Find the first character in tree order that matches the following criteria:
// - The character is from a Text node that is a descendant of the element whose directionality is being determined.
// - The character is of bidirectional character type L, AL, or R. [BIDI]
// - The character is not in a Text node that has an ancestor element that is a descendant of
// the element whose directionality is being determined and that is either:
// - FIXME: A bdi element.
// - A script element.
// - A style element.
// - A textarea element.
// - An element with a dir attribute in a defined state.
Optional<u32> found_character;
Optional<Unicode::BidirectionalClass> found_character_bidi_class;
for_each_in_subtree_of_type<Text>([&](Text const& text_node) {
// Discard not-allowed ancestors
for (auto* ancestor = text_node.parent(); ancestor && ancestor != this; ancestor = ancestor->parent()) {
if (is<HTML::HTMLScriptElement>(*ancestor) || is<HTML::HTMLStyleElement>(*ancestor) || is<HTML::HTMLTextAreaElement>(*ancestor))
return IterationDecision::Continue;
if (ancestor->is_element()) {
auto ancestor_element = static_cast<Element const*>(ancestor);
if (ancestor_element->dir().has_value())
return IterationDecision::Continue;
}
}
// Look for matching characters
for (auto code_point : Utf8View(text_node.data())) {
auto bidi_class = Unicode::bidirectional_class(code_point);
if (first_is_one_of(bidi_class, Unicode::BidirectionalClass::L, Unicode::BidirectionalClass::AL, Unicode::BidirectionalClass::R)) {
found_character = code_point;
found_character_bidi_class = bidi_class;
return IterationDecision::Break;
}
}
return IterationDecision::Continue;
});
// If such a character is found and it is of bidirectional character type AL or R,
// the directionality of the element is 'rtl'.
if (found_character.has_value()
&& first_is_one_of(found_character_bidi_class.value(), Unicode::BidirectionalClass::AL, Unicode::BidirectionalClass::R)) {
return Directionality::Rtl;
}
// If such a character is found and it is of bidirectional character type L,
// the directionality of the element is 'ltr'.
if (found_character.has_value() && found_character_bidi_class.value() == Unicode::BidirectionalClass::L) {
return Directionality::Ltr;
}
// Otherwise, if the element is a document element, the directionality of the element is 'ltr'.
else if (is_document_element()) {
return Directionality::Ltr;
}
// Otherwise, the directionality of the element is the same as the element's parent element's directionality.
else {
return parent_element()->directionality();
}
}
// If the element has a parent element and the dir attribute is not in a defined state
// (i.e. it is not present or has an invalid value)
if (parent_element() && !dir.has_value()) {
// The directionality of the element is the same as the element's parent element's directionality.
return parent_element()->directionality();
}
VERIFY_NOT_REACHED();
}
}

14
Userland/Libraries/LibWeb/DOM/Element.h
View File

@ -325,6 +325,19 @@ public:
CSSPixelPoint scroll_offset(ScrollOffsetFor type) const { return m_scroll_offset[to_underlying(type)]; }
void set_scroll_offset(ScrollOffsetFor type, CSSPixelPoint offset) { m_scroll_offset[to_underlying(type)] = offset; }
enum class Dir {
Ltr,
Rtl,
Auto,
};
Optional<Dir> dir() const { return m_dir; }
enum class Directionality {
Ltr,
Rtl,
};
Directionality directionality() const;
protected:
Element(Document&, DOM::QualifiedName);
virtual void initialize(JS::Realm&) override;
@ -358,6 +371,7 @@ private:
Array<HashMap<DeprecatedFlyString, CSS::StyleProperty>, to_underlying(CSS::Selector::PseudoElement::PseudoElementCount)> m_pseudo_element_custom_properties;
Vector<FlyString> m_classes;
Optional<Dir> m_dir;
Array<JS::GCPtr<Layout::Node>, to_underlying(CSS::Selector::PseudoElement::PseudoElementCount)> m_pseudo_element_nodes;