ladybird/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
2021-11-10 14:38:49 +01:00

914 lines
37 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, the SerenityOS developers.
* Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/QuickSort.h>
#include <LibGfx/Font.h>
#include <LibGfx/FontDatabase.h>
#include <LibWeb/CSS/CSSStyleRule.h>
#include <LibWeb/CSS/Parser/Parser.h>
#include <LibWeb/CSS/SelectorEngine.h>
#include <LibWeb/CSS/StyleComputer.h>
#include <LibWeb/CSS/StyleSheet.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/Dump.h>
#include <LibWeb/FontCache.h>
#include <LibWeb/Page/BrowsingContext.h>
#include <ctype.h>
#include <stdio.h>
namespace Web::CSS {
StyleComputer::StyleComputer(DOM::Document& document)
: m_document(document)
{
}
StyleComputer::~StyleComputer()
{
}
static StyleSheet& default_stylesheet()
{
static StyleSheet* sheet;
if (!sheet) {
extern char const 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 char const quirks_mode_stylesheet_source[];
String css = quirks_mode_stylesheet_source;
sheet = parse_css(CSS::ParsingContext(), css).leak_ref();
}
return *sheet;
}
template<typename Callback>
void StyleComputer::for_each_stylesheet(CascadeOrigin cascade_origin, Callback callback) const
{
if (cascade_origin == CascadeOrigin::Any || cascade_origin == CascadeOrigin::UserAgent) {
callback(default_stylesheet());
if (document().in_quirks_mode())
callback(quirks_mode_stylesheet());
}
if (cascade_origin == CascadeOrigin::Any || cascade_origin == CascadeOrigin::Author) {
for (auto& sheet : document().style_sheets().sheets()) {
callback(sheet);
}
}
}
Vector<MatchingRule> StyleComputer::collect_matching_rules(DOM::Element const& element, CascadeOrigin declaration_type) const
{
Vector<MatchingRule> matching_rules;
size_t style_sheet_index = 0;
for_each_stylesheet(declaration_type, [&](auto& sheet) {
size_t rule_index = 0;
static_cast<CSSStyleSheet const&>(sheet).for_each_effective_style_rule([&](auto const& rule) {
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, selector.specificity() });
break;
}
++selector_index;
}
++rule_index;
});
++style_sheet_index;
});
return matching_rules;
}
void StyleComputer::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;
});
}
enum class Edge {
Top,
Right,
Bottom,
Left,
All,
};
static bool contains(Edge a, Edge b)
{
return a == b || b == Edge::All;
}
static void set_property_expanding_shorthands(StyleProperties& style, CSS::PropertyID property_id, StyleValue const& value, DOM::Document& document)
{
auto assign_edge_values = [&style](PropertyID top_property, PropertyID right_property, PropertyID bottom_property, PropertyID left_property, auto const& values) {
if (values.size() == 4) {
style.set_property(top_property, values[0]);
style.set_property(right_property, values[1]);
style.set_property(bottom_property, values[2]);
style.set_property(left_property, values[3]);
} else if (values.size() == 3) {
style.set_property(top_property, values[0]);
style.set_property(right_property, values[1]);
style.set_property(bottom_property, values[2]);
style.set_property(left_property, values[1]);
} else if (values.size() == 2) {
style.set_property(top_property, values[0]);
style.set_property(right_property, values[1]);
style.set_property(bottom_property, values[0]);
style.set_property(left_property, values[1]);
} else if (values.size() == 1) {
style.set_property(top_property, values[0]);
style.set_property(right_property, values[0]);
style.set_property(bottom_property, values[0]);
style.set_property(left_property, values[0]);
}
};
if (property_id == CSS::PropertyID::TextDecoration) {
if (value.is_text_decoration()) {
auto& text_decoration = value.as_text_decoration();
style.set_property(CSS::PropertyID::TextDecorationLine, text_decoration.line());
style.set_property(CSS::PropertyID::TextDecorationStyle, text_decoration.style());
style.set_property(CSS::PropertyID::TextDecorationColor, text_decoration.color());
return;
}
style.set_property(CSS::PropertyID::TextDecorationLine, value);
style.set_property(CSS::PropertyID::TextDecorationStyle, value);
style.set_property(CSS::PropertyID::TextDecorationColor, value);
return;
}
if (property_id == CSS::PropertyID::Overflow) {
if (value.is_overflow()) {
auto& overflow = value.as_overflow();
style.set_property(CSS::PropertyID::OverflowX, overflow.overflow_x());
style.set_property(CSS::PropertyID::OverflowY, overflow.overflow_y());
return;
}
style.set_property(CSS::PropertyID::OverflowX, value);
style.set_property(CSS::PropertyID::OverflowY, value);
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);
// FIXME: Also reset border-image, in line with the spec: https://www.w3.org/TR/css-backgrounds-3/#border-shorthands
return;
}
if (property_id == CSS::PropertyID::BorderRadius) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::BorderTopLeftRadius, PropertyID::BorderTopRightRadius, PropertyID::BorderBottomRightRadius, PropertyID::BorderBottomLeftRadius, values_list.values());
return;
}
style.set_property(CSS::PropertyID::BorderTopLeftRadius, value);
style.set_property(CSS::PropertyID::BorderTopRightRadius, value);
style.set_property(CSS::PropertyID::BorderBottomRightRadius, value);
style.set_property(CSS::PropertyID::BorderBottomLeftRadius, value);
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;
}
if (value.is_border()) {
auto& border = value.as_border();
if (contains(Edge::Top, edge)) {
style.set_property(PropertyID::BorderTopWidth, border.border_width());
style.set_property(PropertyID::BorderTopStyle, border.border_style());
style.set_property(PropertyID::BorderTopColor, border.border_color());
}
if (contains(Edge::Right, edge)) {
style.set_property(PropertyID::BorderRightWidth, border.border_width());
style.set_property(PropertyID::BorderRightStyle, border.border_style());
style.set_property(PropertyID::BorderRightColor, border.border_color());
}
if (contains(Edge::Bottom, edge)) {
style.set_property(PropertyID::BorderBottomWidth, border.border_width());
style.set_property(PropertyID::BorderBottomStyle, border.border_style());
style.set_property(PropertyID::BorderBottomColor, border.border_color());
}
if (contains(Edge::Left, edge)) {
style.set_property(PropertyID::BorderLeftWidth, border.border_width());
style.set_property(PropertyID::BorderLeftStyle, border.border_style());
style.set_property(PropertyID::BorderLeftColor, border.border_color());
}
return;
}
return;
}
if (property_id == CSS::PropertyID::BorderStyle) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::BorderTopStyle, PropertyID::BorderRightStyle, PropertyID::BorderBottomStyle, PropertyID::BorderLeftStyle, values_list.values());
return;
}
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) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::BorderTopWidth, PropertyID::BorderRightWidth, PropertyID::BorderBottomWidth, PropertyID::BorderLeftWidth, values_list.values());
return;
}
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) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::BorderTopColor, PropertyID::BorderRightColor, PropertyID::BorderBottomColor, PropertyID::BorderLeftColor, values_list.values());
return;
}
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) {
auto set_single_background = [&](CSS::BackgroundStyleValue const& background) {
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundColor, background.color(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundImage, background.image(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundPosition, background.position(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundRepeat, background.repeat(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundAttachment, background.attachment(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundOrigin, background.origin(), document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundClip, background.clip(), document);
};
if (value.is_background()) {
auto& background = value.as_background();
set_single_background(background);
return;
}
if (value.is_value_list()) {
auto& background_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_list.is_empty()) {
auto& background = background_list.first();
if (background.is_background())
set_single_background(background.as_background());
}
return;
}
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundColor, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundImage, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundPosition, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundRepeat, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundAttachment, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundOrigin, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundClip, value, document);
return;
}
if (property_id == CSS::PropertyID::BackgroundAttachment) {
if (value.is_value_list()) {
auto& background_attachment_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_attachment_list.is_empty()) {
auto& background_attachment = background_attachment_list.first();
style.set_property(CSS::PropertyID::BackgroundAttachment, background_attachment);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundAttachment, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundClip) {
if (value.is_value_list()) {
auto& background_clip_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_clip_list.is_empty()) {
auto& background_clip = background_clip_list.first();
style.set_property(CSS::PropertyID::BackgroundClip, background_clip);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundClip, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundImage) {
if (value.is_value_list()) {
auto& background_image_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_image_list.is_empty()) {
auto& background_image = background_image_list.first();
style.set_property(CSS::PropertyID::BackgroundImage, background_image);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundImage, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundOrigin) {
if (value.is_value_list()) {
auto& background_origin_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_origin_list.is_empty()) {
auto& background_origin = background_origin_list.first();
style.set_property(CSS::PropertyID::BackgroundOrigin, background_origin);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundOrigin, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundPosition) {
if (value.is_value_list()) {
auto& background_position_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_position_list.is_empty()) {
auto& background_position = background_position_list.first();
style.set_property(CSS::PropertyID::BackgroundPosition, background_position);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundPosition, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundRepeat) {
if (value.is_value_list()) {
auto& background_repeat_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_repeat_list.is_empty()) {
auto& background_repeat = background_repeat_list.first();
style.set_property(CSS::PropertyID::BackgroundRepeat, background_repeat);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundRepeat, value);
return;
}
if (property_id == CSS::PropertyID::BackgroundSize) {
if (value.is_value_list()) {
auto& background_size_list = value.as_value_list().values();
// FIXME: Handle multiple backgrounds.
if (!background_size_list.is_empty()) {
auto& background_size = background_size_list.first();
style.set_property(CSS::PropertyID::BackgroundSize, background_size);
}
return;
}
style.set_property(CSS::PropertyID::BackgroundSize, value);
return;
}
if (property_id == CSS::PropertyID::Margin) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::MarginTop, PropertyID::MarginRight, PropertyID::MarginBottom, PropertyID::MarginLeft, values_list.values());
return;
}
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 (property_id == CSS::PropertyID::Padding) {
if (value.is_value_list()) {
auto& values_list = value.as_value_list();
assign_edge_values(PropertyID::PaddingTop, PropertyID::PaddingRight, PropertyID::PaddingBottom, PropertyID::PaddingLeft, values_list.values());
return;
}
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 (property_id == CSS::PropertyID::ListStyle) {
if (value.is_list_style()) {
auto& list_style = value.as_list_style();
style.set_property(CSS::PropertyID::ListStylePosition, list_style.position());
style.set_property(CSS::PropertyID::ListStyleImage, list_style.image());
style.set_property(CSS::PropertyID::ListStyleType, list_style.style_type());
return;
}
style.set_property(CSS::PropertyID::ListStylePosition, value);
style.set_property(CSS::PropertyID::ListStyleImage, value);
style.set_property(CSS::PropertyID::ListStyleType, value);
return;
}
if (property_id == CSS::PropertyID::Font) {
if (value.is_font()) {
auto& font_shorthand = value.as_font();
style.set_property(CSS::PropertyID::FontSize, font_shorthand.font_size());
style.set_property(CSS::PropertyID::FontFamily, font_shorthand.font_families());
style.set_property(CSS::PropertyID::FontStyle, font_shorthand.font_style());
style.set_property(CSS::PropertyID::FontWeight, font_shorthand.font_weight());
style.set_property(CSS::PropertyID::LineHeight, font_shorthand.line_height());
// FIXME: Implement font-stretch and font-variant
return;
}
style.set_property(CSS::PropertyID::FontSize, value);
style.set_property(CSS::PropertyID::FontFamily, value);
style.set_property(CSS::PropertyID::FontStyle, value);
style.set_property(CSS::PropertyID::FontWeight, value);
style.set_property(CSS::PropertyID::LineHeight, value);
// FIXME: Implement font-stretch and font-variant
return;
}
if (property_id == CSS::PropertyID::Flex) {
if (value.is_flex()) {
auto& flex = value.as_flex();
style.set_property(CSS::PropertyID::FlexGrow, flex.grow());
style.set_property(CSS::PropertyID::FlexShrink, flex.shrink());
style.set_property(CSS::PropertyID::FlexBasis, flex.basis());
return;
}
style.set_property(CSS::PropertyID::FlexGrow, value);
style.set_property(CSS::PropertyID::FlexShrink, value);
style.set_property(CSS::PropertyID::FlexBasis, value);
return;
}
if (property_id == CSS::PropertyID::FlexFlow) {
if (value.is_flex_flow()) {
auto& flex_flow = value.as_flex_flow();
style.set_property(CSS::PropertyID::FlexDirection, flex_flow.flex_direction());
style.set_property(CSS::PropertyID::FlexWrap, flex_flow.flex_wrap());
return;
}
style.set_property(CSS::PropertyID::FlexDirection, value);
style.set_property(CSS::PropertyID::FlexWrap, value);
return;
}
style.set_property(property_id, value);
}
StyleComputer::CustomPropertyResolutionTuple StyleComputer::resolve_custom_property_with_specificity(DOM::Element& element, String const& custom_property_name) const
{
if (auto maybe_property = element.resolve_custom_property(custom_property_name); maybe_property.has_value())
return maybe_property.value();
auto parent_element = element.parent_element();
CustomPropertyResolutionTuple parent_resolved {};
if (parent_element)
parent_resolved = resolve_custom_property_with_specificity(*parent_element, custom_property_name);
auto matching_rules = collect_matching_rules(element);
sort_matching_rules(matching_rules);
for (int i = matching_rules.size() - 1; i >= 0; --i) {
auto& match = matching_rules[i];
if (match.specificity < parent_resolved.specificity)
continue;
auto custom_property_style = verify_cast<PropertyOwningCSSStyleDeclaration>(match.rule->declaration()).custom_property(custom_property_name);
if (custom_property_style.has_value()) {
element.add_custom_property(custom_property_name, { custom_property_style.value(), match.specificity });
return { custom_property_style.value(), match.specificity };
}
}
return parent_resolved;
}
Optional<StyleProperty> StyleComputer::resolve_custom_property(DOM::Element& element, String const& custom_property_name) const
{
auto resolved_with_specificity = resolve_custom_property_with_specificity(element, custom_property_name);
return resolved_with_specificity.style;
}
struct MatchingDeclarations {
Vector<MatchingRule> user_agent_rules;
Vector<MatchingRule> author_rules;
};
void StyleComputer::cascade_declarations(StyleProperties& style, DOM::Element& element, Vector<MatchingRule> const& matching_rules, CascadeOrigin cascade_origin, bool important) const
{
for (auto& match : matching_rules) {
for (auto& property : verify_cast<PropertyOwningCSSStyleDeclaration>(match.rule->declaration()).properties()) {
if (important != property.important)
continue;
auto property_value = property.value;
if (property.value->is_custom_property()) {
auto custom_property_name = property.value->as_custom_property().custom_property_name();
auto resolved = resolve_custom_property(element, custom_property_name);
if (resolved.has_value()) {
property_value = resolved.value().value;
}
}
set_property_expanding_shorthands(style, property.property_id, property_value, m_document);
}
}
if (cascade_origin == CascadeOrigin::Author) {
if (auto* inline_style = verify_cast<ElementInlineCSSStyleDeclaration>(element.inline_style())) {
for (auto& property : inline_style->properties()) {
if (important != property.important)
continue;
set_property_expanding_shorthands(style, property.property_id, property.value, m_document);
}
}
}
}
// https://www.w3.org/TR/css-cascade/#cascading
void StyleComputer::compute_cascaded_values(StyleProperties& style, DOM::Element& element) const
{
// First, we collect all the CSS rules whose selectors match `element`:
MatchingRuleSet matching_rule_set;
matching_rule_set.user_agent_rules = collect_matching_rules(element, CascadeOrigin::UserAgent);
sort_matching_rules(matching_rule_set.user_agent_rules);
matching_rule_set.author_rules = collect_matching_rules(element, CascadeOrigin::Author);
sort_matching_rules(matching_rule_set.author_rules);
// Then we apply the declarations from the matched rules in cascade order:
// Normal user agent declarations
cascade_declarations(style, element, matching_rule_set.user_agent_rules, CascadeOrigin::UserAgent, false);
// FIXME: Normal user declarations
// Normal author declarations
cascade_declarations(style, element, matching_rule_set.author_rules, CascadeOrigin::Author, false);
// Author presentational hints (NOTE: The spec doesn't say exactly how to prioritize these.)
element.apply_presentational_hints(style);
// FIXME: Animation declarations [css-animations-1]
// Important author declarations
cascade_declarations(style, element, matching_rule_set.author_rules, CascadeOrigin::Author, true);
// FIXME: Important user declarations
// Important user agent declarations
cascade_declarations(style, element, matching_rule_set.user_agent_rules, CascadeOrigin::UserAgent, true);
// FIXME: Transition declarations [css-transitions-1]
}
static NonnullRefPtr<StyleValue> get_initial_value(CSS::PropertyID property_id)
{
auto value = property_initial_value(property_id);
if (!value)
return InitialStyleValue::the();
return value.release_nonnull();
};
static NonnullRefPtr<StyleValue> get_inherit_value(CSS::PropertyID property_id, DOM::Element const* element)
{
if (!element || !element->parent_element() || !element->parent_element()->specified_css_values())
return get_initial_value(property_id);
auto& map = element->parent_element()->specified_css_values()->properties();
auto it = map.find(property_id);
VERIFY(it != map.end());
return *it->value;
};
void StyleComputer::compute_defaulted_property_value(StyleProperties& style, DOM::Element const* element, CSS::PropertyID property_id) const
{
// FIXME: If we don't know the correct initial value for a property, we fall back to InitialStyleValue.
auto it = style.m_property_values.find(property_id);
if (it == style.m_property_values.end()) {
if (is_inherited_property(property_id))
style.m_property_values.set(property_id, get_inherit_value(property_id, element));
else
style.m_property_values.set(property_id, get_initial_value(property_id));
return;
}
if (it->value->is_initial()) {
it->value = get_initial_value(property_id);
return;
}
if (it->value->is_inherit()) {
it->value = get_inherit_value(property_id, element);
return;
}
}
// https://www.w3.org/TR/css-cascade/#defaulting
void StyleComputer::compute_defaulted_values(StyleProperties& style, DOM::Element const* element) const
{
// Walk the list of all known CSS properties and:
// - Add them to `style` if they are missing.
// - Resolve `inherit` and `initial` as needed.
for (auto i = to_underlying(CSS::first_longhand_property_id); i <= to_underlying(CSS::last_longhand_property_id); ++i) {
auto property_id = (CSS::PropertyID)i;
compute_defaulted_property_value(style, element, property_id);
}
}
void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* element) const
{
// To compute the font, first ensure that we've defaulted the relevant CSS font properties.
// FIXME: This should be more sophisticated.
compute_defaulted_property_value(style, element, CSS::PropertyID::FontFamily);
compute_defaulted_property_value(style, element, CSS::PropertyID::FontSize);
compute_defaulted_property_value(style, element, CSS::PropertyID::FontWeight);
auto viewport_rect = document().browsing_context()->viewport_rect();
auto font_size = style.property(CSS::PropertyID::FontSize).value();
auto font_weight = style.property(CSS::PropertyID::FontWeight).value();
int weight = Gfx::FontWeight::Regular;
if (font_weight->is_identifier()) {
switch (static_cast<IdentifierStyleValue const&>(*font_weight).id()) {
case CSS::ValueID::Normal:
weight = Gfx::FontWeight::Regular;
break;
case CSS::ValueID::Bold:
weight = Gfx::FontWeight::Bold;
break;
case CSS::ValueID::Lighter:
// FIXME: This should be relative to the parent.
weight = Gfx::FontWeight::Regular;
break;
case CSS::ValueID::Bolder:
// FIXME: This should be relative to the parent.
weight = Gfx::FontWeight::Bold;
break;
default:
break;
}
} else if (font_weight->has_integer()) {
int font_weight_integer = font_weight->to_integer();
if (font_weight_integer <= Gfx::FontWeight::Regular)
weight = Gfx::FontWeight::Regular;
else if (font_weight_integer <= Gfx::FontWeight::Bold)
weight = Gfx::FontWeight::Bold;
else
weight = Gfx::FontWeight::Black;
}
// FIXME: calc() for font-weight
bool bold = weight > Gfx::FontWeight::Regular;
int size = 10;
if (font_size->is_identifier()) {
switch (static_cast<const IdentifierStyleValue&>(*font_size).id()) {
case CSS::ValueID::XxSmall:
case CSS::ValueID::XSmall:
case CSS::ValueID::Small:
case CSS::ValueID::Medium:
// FIXME: Should be based on "user's default font size"
size = 10;
break;
case CSS::ValueID::Large:
case CSS::ValueID::XLarge:
case CSS::ValueID::XxLarge:
case CSS::ValueID::XxxLarge:
// FIXME: Should be based on "user's default font size"
size = 12;
break;
case CSS::ValueID::Smaller:
case CSS::ValueID::Larger:
// FIXME: Should be based on parent element
break;
default:
break;
}
} else {
// FIXME: Get the root element font.
float root_font_size = 10;
Gfx::FontMetrics font_metrics;
if (element && element->parent_element() && element->parent_element()->specified_css_values())
font_metrics = element->parent_element()->specified_css_values()->computed_font().metrics('M');
else
font_metrics = Gfx::FontDatabase::default_font().metrics('M');
Optional<Length> maybe_length;
if (font_size->is_length()) {
maybe_length = font_size->to_length();
if (maybe_length->is_percentage()) {
auto parent_font_size = size;
if (element && element->parent_element() && element->parent_element()->layout_node() && element->parent_element()->specified_css_values()) {
auto value = element->parent_element()->specified_css_values()->property(CSS::PropertyID::FontSize).value();
if (value->is_length()) {
auto length = static_cast<LengthStyleValue const&>(*value).to_length();
if (length.is_absolute() || length.is_relative())
parent_font_size = length.to_px(viewport_rect, font_metrics, root_font_size);
}
}
maybe_length = Length::make_px(maybe_length->raw_value() / 100.0f * (parent_font_size));
}
} else if (font_size->is_calculated()) {
Length length = Length(0, Length::Type::Calculated);
length.set_calculated_style(verify_cast<CalculatedStyleValue>(font_size.ptr()));
maybe_length = length;
}
if (maybe_length.has_value()) {
// FIXME: Support font-size: calc(...)
if (!maybe_length->is_calculated()) {
auto px = maybe_length.value().to_px(viewport_rect, font_metrics, root_font_size);
if (px != 0)
size = px;
}
}
}
// FIXME: Implement the full font-matching algorithm: https://www.w3.org/TR/css-fonts-4/#font-matching-algorithm
// Note: This is modified by the find_font() lambda
FontSelector font_selector;
bool monospace = false;
auto find_font = [&](String const& family) -> RefPtr<Gfx::Font> {
font_selector = { family, size, weight };
if (auto found_font = FontCache::the().get(font_selector))
return found_font;
if (auto found_font = Gfx::FontDatabase::the().get(family, size, weight))
return found_font;
return {};
};
// FIXME: Replace hard-coded font names with a relevant call to FontDatabase.
// Currently, we cannot request the default font's name, or request it at a specific size and weight.
// So, hard-coded font names it is.
auto find_generic_font = [&](ValueID font_id) -> RefPtr<Gfx::Font> {
switch (font_id) {
case ValueID::Monospace:
case ValueID::UiMonospace:
monospace = true;
return find_font("Csilla");
case ValueID::Serif:
case ValueID::SansSerif:
case ValueID::Cursive:
case ValueID::Fantasy:
case ValueID::UiSerif:
case ValueID::UiSansSerif:
case ValueID::UiRounded:
return find_font("Katica");
default:
return {};
}
};
RefPtr<Gfx::Font> found_font;
auto family_value = style.property(PropertyID::FontFamily).value();
if (family_value->is_value_list()) {
auto& family_list = static_cast<StyleValueList const&>(*family_value).values();
for (auto& family : family_list) {
if (family.is_identifier()) {
found_font = find_generic_font(family.to_identifier());
} else if (family.is_string()) {
found_font = find_font(family.to_string());
}
if (found_font)
break;
}
} else if (family_value->is_identifier()) {
found_font = find_generic_font(family_value->to_identifier());
} else if (family_value->is_string()) {
found_font = find_font(family_value->to_string());
}
if (!found_font) {
found_font = StyleProperties::font_fallback(monospace, bold);
}
FontCache::the().set(font_selector, *found_font);
style.set_computed_font(found_font.release_nonnull());
}
void StyleComputer::absolutize_values(StyleProperties& style, DOM::Element const*) const
{
auto viewport_rect = document().browsing_context()->viewport_rect();
auto font_metrics = style.computed_font().metrics('M');
// FIXME: Get the root element font.
float root_font_size = 10;
for (auto& it : style.properties()) {
it.value->visit_lengths([&](Length& length) {
if (length.is_absolute() || length.is_relative()) {
auto px = length.to_px(viewport_rect, font_metrics, root_font_size);
length = Length::make_px(px);
}
});
}
}
NonnullRefPtr<StyleProperties> StyleComputer::create_document_style() const
{
auto style = StyleProperties::create();
compute_font(style, nullptr);
compute_defaulted_values(style, nullptr);
absolutize_values(style, nullptr);
return style;
}
NonnullRefPtr<StyleProperties> StyleComputer::compute_style(DOM::Element& element) const
{
auto style = StyleProperties::create();
// 1. Perform the cascade. This produces the "specified style"
compute_cascaded_values(style, element);
// 2. Compute the font, since that may be needed for font-relative CSS units
compute_font(style, &element);
// 3. Absolutize values, turning font/viewport relative lengths into absolute lengths
absolutize_values(style, &element);
// 4. Default the values, applying inheritance and 'initial' as needed
compute_defaulted_values(style, &element);
return style;
}
}