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ladybird/Libraries/LibWeb/CSS/StyleResolver.cpp
Andreas Kling 29a4da30b7 LibWeb: Make DOM::Node::create_layout_node() not need parent's style 
The StyleResolver can find the specified CSS values for the parent
element via the DOM. Forcing everyone to locate specified values for
their parent was completely unnecessary.
2021-01-06 14:58:48 +01:00

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/QuickSort.h>
#include <LibWeb/CSS/Parser/CSSParser.h>
#include <LibWeb/CSS/SelectorEngine.h>
#include <LibWeb/CSS/StyleResolver.h>
#include <LibWeb/CSS/StyleSheet.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/Dump.h>
#include <ctype.h>
#include <stdio.h>
namespace Web::CSS {
StyleResolver::StyleResolver(DOM::Document& document)
: m_document(document)
{
}
StyleResolver::~StyleResolver()
{
}
static StyleSheet& default_stylesheet()
{
static StyleSheet* sheet;
if (!sheet) {
extern const char default_stylesheet_source[];
String css = default_stylesheet_source;
sheet = parse_css(CSS::ParsingContext(), css).leak_ref();
}
return *sheet;
}
static StyleSheet& quirks_mode_stylesheet()
{
static StyleSheet* sheet;
if (!sheet) {
extern const char quirks_mode_stylesheet_source[];
String css = quirks_mode_stylesheet_source;
sheet = parse_css(CSS::ParsingContext(), css).leak_ref();
}
return *sheet;
}
template<typename Callback>
void StyleResolver::for_each_stylesheet(Callback callback) const
{
callback(default_stylesheet());
if (document().in_quirks_mode())
callback(quirks_mode_stylesheet());
for (auto& sheet : document().style_sheets().sheets()) {
callback(sheet);
}
}
Vector<MatchingRule> StyleResolver::collect_matching_rules(const DOM::Element& element) const
{
Vector<MatchingRule> matching_rules;
size_t style_sheet_index = 0;
for_each_stylesheet([&](auto& sheet) {
size_t rule_index = 0;
for (auto& rule : sheet.rules()) {
size_t selector_index = 0;
for (auto& selector : rule.selectors()) {
if (SelectorEngine::matches(selector, element)) {
matching_rules.append({ rule, style_sheet_index, rule_index, selector_index });
break;
}
++selector_index;
}
++rule_index;
}
++style_sheet_index;
});
return matching_rules;
}
void StyleResolver::sort_matching_rules(Vector<MatchingRule>& matching_rules) const
{
quick_sort(matching_rules, [&](MatchingRule& a, MatchingRule& b) {
auto& a_selector = a.rule->selectors()[a.selector_index];
auto& b_selector = b.rule->selectors()[b.selector_index];
auto a_specificity = a_selector.specificity();
auto b_specificity = b_selector.specificity();
if (a_selector.specificity() == b_selector.specificity()) {
if (a.style_sheet_index == b.style_sheet_index)
return a.rule_index < b.rule_index;
return a.style_sheet_index < b.style_sheet_index;
}
return a_specificity < b_specificity;
});
}
bool StyleResolver::is_inherited_property(CSS::PropertyID property_id)
{
static HashTable<CSS::PropertyID> inherited_properties;
if (inherited_properties.is_empty()) {
inherited_properties.set(CSS::PropertyID::BorderCollapse);
inherited_properties.set(CSS::PropertyID::BorderSpacing);
inherited_properties.set(CSS::PropertyID::Color);
inherited_properties.set(CSS::PropertyID::FontFamily);
inherited_properties.set(CSS::PropertyID::FontSize);
inherited_properties.set(CSS::PropertyID::FontStyle);
inherited_properties.set(CSS::PropertyID::FontVariant);
inherited_properties.set(CSS::PropertyID::FontWeight);
inherited_properties.set(CSS::PropertyID::LetterSpacing);
inherited_properties.set(CSS::PropertyID::LineHeight);
inherited_properties.set(CSS::PropertyID::ListStyle);
inherited_properties.set(CSS::PropertyID::ListStyleImage);
inherited_properties.set(CSS::PropertyID::ListStylePosition);
inherited_properties.set(CSS::PropertyID::ListStyleType);
inherited_properties.set(CSS::PropertyID::TextAlign);
inherited_properties.set(CSS::PropertyID::TextIndent);
inherited_properties.set(CSS::PropertyID::TextTransform);
inherited_properties.set(CSS::PropertyID::Visibility);
inherited_properties.set(CSS::PropertyID::WhiteSpace);
inherited_properties.set(CSS::PropertyID::WordSpacing);
// FIXME: This property is not supposed to be inherited, but we currently
// rely on inheritance to propagate decorations into line boxes.
inherited_properties.set(CSS::PropertyID::TextDecorationLine);
}
return inherited_properties.contains(property_id);
}
static Vector<String> split_on_whitespace(const StringView& string)
{
if (string.is_empty())
return {};
Vector<String> v;
size_t substart = 0;
for (size_t i = 0; i < string.length(); ++i) {
char ch = string.characters_without_null_termination()[i];
if (isspace(ch)) {
size_t sublen = i - substart;
if (sublen != 0)
v.append(string.substring_view(substart, sublen));
substart = i + 1;
}
}
size_t taillen = string.length() - substart;
if (taillen != 0)
v.append(string.substring_view(substart, taillen));
return v;
}
enum class Edge {
Top,
Right,
Bottom,
Left,
All,
};
static bool contains(Edge a, Edge b)
{
return a == b || b == Edge::All;
}
static inline void set_property_border_width(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_length());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopWidth, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightWidth, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomWidth, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftWidth, value);
}
static inline void set_property_border_color(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_color());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopColor, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightColor, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomColor, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftColor, value);
}
static inline void set_property_border_style(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_string());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopStyle, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightStyle, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomStyle, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftStyle, value);
}
static void set_property_expanding_shorthands(StyleProperties& style, CSS::PropertyID property_id, const StyleValue& value, DOM::Document& document)
{
CSS::ParsingContext context(document);
if (property_id == CSS::PropertyID::TextDecoration) {
switch (value.to_identifier()) {
case CSS::ValueID::None:
case CSS::ValueID::Underline:
case CSS::ValueID::Overline:
case CSS::ValueID::LineThrough:
case CSS::ValueID::Blink:
set_property_expanding_shorthands(style, CSS::PropertyID::TextDecorationLine, value, document);
default:
break;
}
return;
}
if (property_id == CSS::PropertyID::Border) {
set_property_expanding_shorthands(style, CSS::PropertyID::BorderTop, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderRight, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderBottom, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderLeft, value, document);
return;
}
if (property_id == CSS::PropertyID::BorderTop
|| property_id == CSS::PropertyID::BorderRight
|| property_id == CSS::PropertyID::BorderBottom
|| property_id == CSS::PropertyID::BorderLeft) {
Edge edge = Edge::All;
switch (property_id) {
case CSS::PropertyID::BorderTop:
edge = Edge::Top;
break;
case CSS::PropertyID::BorderRight:
edge = Edge::Right;
break;
case CSS::PropertyID::BorderBottom:
edge = Edge::Bottom;
break;
case CSS::PropertyID::BorderLeft:
edge = Edge::Left;
break;
default:
break;
}
auto parts = split_on_whitespace(value.to_string());
if (value.is_length()) {
set_property_border_width(style, value, edge);
return;
}
if (value.is_color()) {
set_property_border_color(style, value, edge);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (parts.size() == 1) {
if (auto value = parse_line_style(context, parts[0])) {
set_property_border_style(style, value.release_nonnull(), edge);
set_property_border_color(style, ColorStyleValue::create(Gfx::Color::Black), edge);
set_property_border_width(style, LengthStyleValue::create(Length(3, Length::Type::Px)), edge);
return;
}
}
RefPtr<LengthStyleValue> line_width_value;
RefPtr<ColorStyleValue> color_value;
RefPtr<StringStyleValue> line_style_value;
for (auto& part : parts) {
if (auto value = parse_line_width(context, part)) {
if (line_width_value)
return;
line_width_value = move(value);
continue;
}
if (auto value = parse_color(context, part)) {
if (color_value)
return;
color_value = move(value);
continue;
}
if (auto value = parse_line_style(context, part)) {
if (line_style_value)
return;
line_style_value = move(value);
continue;
}
}
if (line_width_value)
set_property_border_width(style, line_width_value.release_nonnull(), edge);
if (color_value)
set_property_border_color(style, color_value.release_nonnull(), edge);
if (line_style_value)
set_property_border_style(style, line_style_value.release_nonnull(), edge);
return;
}
return;
}
if (property_id == CSS::PropertyID::BorderStyle) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[1]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::BorderTopStyle, *top);
style.set_property(CSS::PropertyID::BorderRightStyle, *right);
style.set_property(CSS::PropertyID::BorderBottomStyle, *bottom);
style.set_property(CSS::PropertyID::BorderLeftStyle, *left);
}
} else {
style.set_property(CSS::PropertyID::BorderTopStyle, value);
style.set_property(CSS::PropertyID::BorderRightStyle, value);
style.set_property(CSS::PropertyID::BorderBottomStyle, value);
style.set_property(CSS::PropertyID::BorderLeftStyle, value);
}
return;
}
if (property_id == CSS::PropertyID::BorderWidth) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical_border_width = parse_css_value(context, parts[0]);
auto horizontal_border_width = parse_css_value(context, parts[1]);
if (vertical_border_width && horizontal_border_width) {
style.set_property(CSS::PropertyID::BorderTopWidth, *vertical_border_width);
style.set_property(CSS::PropertyID::BorderRightWidth, *horizontal_border_width);
style.set_property(CSS::PropertyID::BorderBottomWidth, *vertical_border_width);
style.set_property(CSS::PropertyID::BorderLeftWidth, *horizontal_border_width);
}
} else {
style.set_property(CSS::PropertyID::BorderTopWidth, value);
style.set_property(CSS::PropertyID::BorderRightWidth, value);
style.set_property(CSS::PropertyID::BorderBottomWidth, value);
style.set_property(CSS::PropertyID::BorderLeftWidth, value);
}
return;
}
if (property_id == CSS::PropertyID::BorderColor) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::BorderTopColor, *top);
style.set_property(CSS::PropertyID::BorderRightColor, *right);
style.set_property(CSS::PropertyID::BorderBottomColor, *bottom);
style.set_property(CSS::PropertyID::BorderLeftColor, *left);
}
} else {
style.set_property(CSS::PropertyID::BorderTopColor, value);
style.set_property(CSS::PropertyID::BorderRightColor, value);
style.set_property(CSS::PropertyID::BorderBottomColor, value);
style.set_property(CSS::PropertyID::BorderLeftColor, value);
}
return;
}
if (property_id == CSS::PropertyID::Background) {
if (value.is_identifier() && static_cast<const IdentifierStyleValue&>(value).id() == CSS::ValueID::None) {
style.set_property(CSS::PropertyID::BackgroundColor, ColorStyleValue::create(Color::Transparent));
return;
}
auto parts = split_on_whitespace(value.to_string());
NonnullRefPtrVector<StyleValue> values;
for (auto& part : parts) {
auto value = parse_css_value(context, part);
if (!value)
return;
values.append(value.release_nonnull());
}
// HACK: Disallow more than one color value in a 'background' shorthand
size_t color_value_count = 0;
for (auto& value : values)
color_value_count += value.is_color();
if (values[0].is_color() && color_value_count == 1)
style.set_property(CSS::PropertyID::BackgroundColor, values[0]);
for (auto& value : values) {
if (!value.is_string())
continue;
auto string = value.to_string();
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundImage, value, document);
}
return;
}
if (property_id == CSS::PropertyID::BackgroundImage) {
if (!value.is_string())
return;
auto string = value.to_string();
if (!string.starts_with("url("))
return;
if (!string.ends_with(')'))
return;
auto url = string.substring_view(4, string.length() - 5);
if (url.length() >= 2 && url.starts_with('"') && url.ends_with('"'))
url = url.substring_view(1, url.length() - 2);
else if (url.length() >= 2 && url.starts_with('\'') && url.ends_with('\''))
url = url.substring_view(1, url.length() - 2);
auto background_image_value = ImageStyleValue::create(document.complete_url(url), document);
style.set_property(CSS::PropertyID::BackgroundImage, move(background_image_value));
return;
}
if (property_id == CSS::PropertyID::Margin) {
if (value.is_length()) {
style.set_property(CSS::PropertyID::MarginTop, value);
style.set_property(CSS::PropertyID::MarginRight, value);
style.set_property(CSS::PropertyID::MarginBottom, value);
style.set_property(CSS::PropertyID::MarginLeft, value);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
if (vertical && horizontal) {
style.set_property(CSS::PropertyID::MarginTop, *vertical);
style.set_property(CSS::PropertyID::MarginBottom, *vertical);
style.set_property(CSS::PropertyID::MarginLeft, *horizontal);
style.set_property(CSS::PropertyID::MarginRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
if (top && horizontal && bottom) {
style.set_property(CSS::PropertyID::MarginTop, *top);
style.set_property(CSS::PropertyID::MarginBottom, *bottom);
style.set_property(CSS::PropertyID::MarginLeft, *horizontal);
style.set_property(CSS::PropertyID::MarginRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::MarginTop, *top);
style.set_property(CSS::PropertyID::MarginBottom, *bottom);
style.set_property(CSS::PropertyID::MarginLeft, *left);
style.set_property(CSS::PropertyID::MarginRight, *right);
}
return;
}
dbg() << "Unsure what to do with CSS margin value '" << value.to_string() << "'";
return;
}
return;
}
if (property_id == CSS::PropertyID::Padding) {
if (value.is_length()) {
style.set_property(CSS::PropertyID::PaddingTop, value);
style.set_property(CSS::PropertyID::PaddingRight, value);
style.set_property(CSS::PropertyID::PaddingBottom, value);
style.set_property(CSS::PropertyID::PaddingLeft, value);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
if (vertical && horizontal) {
style.set_property(CSS::PropertyID::PaddingTop, *vertical);
style.set_property(CSS::PropertyID::PaddingBottom, *vertical);
style.set_property(CSS::PropertyID::PaddingLeft, *horizontal);
style.set_property(CSS::PropertyID::PaddingRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
if (top && bottom && horizontal) {
style.set_property(CSS::PropertyID::PaddingTop, *top);
style.set_property(CSS::PropertyID::PaddingBottom, *bottom);
style.set_property(CSS::PropertyID::PaddingLeft, *horizontal);
style.set_property(CSS::PropertyID::PaddingRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && bottom && left && right) {
style.set_property(CSS::PropertyID::PaddingTop, *top);
style.set_property(CSS::PropertyID::PaddingBottom, *bottom);
style.set_property(CSS::PropertyID::PaddingLeft, *left);
style.set_property(CSS::PropertyID::PaddingRight, *right);
}
return;
}
dbg() << "Unsure what to do with CSS padding value '" << value.to_string() << "'";
return;
}
return;
}
if (property_id == CSS::PropertyID::ListStyle) {
auto parts = split_on_whitespace(value.to_string());
if (!parts.is_empty()) {
auto value = parse_css_value(context, parts[0]);
if (!value)
return;
style.set_property(CSS::PropertyID::ListStyleType, value.release_nonnull());
}
return;
}
style.set_property(property_id, value);
}
NonnullRefPtr<StyleProperties> StyleResolver::resolve_style(const DOM::Element& element) const
{
auto style = StyleProperties::create();
if (auto* parent_style = element.parent_element() ? element.parent_element()->specified_css_values() : nullptr) {
parent_style->for_each_property([&](auto property_id, auto& value) {
if (is_inherited_property(property_id))
set_property_expanding_shorthands(style, property_id, value, m_document);
});
}
element.apply_presentational_hints(*style);
auto matching_rules = collect_matching_rules(element);
sort_matching_rules(matching_rules);
for (auto& match : matching_rules) {
for (auto& property : match.rule->declaration().properties()) {
set_property_expanding_shorthands(style, property.property_id, property.value, m_document);
}
}
if (auto* inline_style = element.inline_style()) {
for (auto& property : inline_style->properties()) {
set_property_expanding_shorthands(style, property.property_id, property.value, m_document);
}
}
return style;
}
}
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