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ladybird/Userland/Libraries/LibWeb/CSS/StyleResolver.cpp
Andreas Kling 23a08fd35a LibWeb: Start absolutizing lengths after performing the CSS cascade 
Once we've performed the cascade on a set of values for an element,
we should have enough information to resolve/absolutize some lengths.

Basically, any CSS length that isn't "auto" or a percentage can be
turned into an absolute length (in pixels) as long as we have the
following information:

- The viewport rect
- The parent element's font
- The document element's font
- The element's own font

To ensure that we can absolutize lengths relative to the element's own
font, we now do a separate first pass where font-related properties are
defaulted (in the cascade spec sense of the word) and become usable.

There's a lot more work to do here, but this should open up a lot of
simplification in layout code, since it will no longer need to care
about relative lengths. Layout still needs to resolve percentages, since
we can't do that for some properties until the containing block
dimensions are known.
2021-09-24 15:01:49 +02:00

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/*
* 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/StyleResolver.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 {
StyleResolver::StyleResolver(DOM::Document& document)
: m_document(document)
{
}
StyleResolver::~StyleResolver()
{
}
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 StyleResolver::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> StyleResolver::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& 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 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;
});
}
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, bool is_internally_generated_pseudo_property = false)
{
if (is_pseudo_property(property_id) && !is_internally_generated_pseudo_property) {
dbgln("Ignoring non-internally-generated pseudo property: {}", string_from_property_id(property_id));
return;
}
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::BackgroundRepeatX, background.repeat_x(), document, true);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundRepeatY, background.repeat_y(), document, true);
};
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::BackgroundRepeatX, value, document, true);
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundRepeatY, value, document, true);
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::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& maybe_background_repeat = background_repeat_list.first();
if (maybe_background_repeat.is_background_repeat()) {
auto& background_repeat = maybe_background_repeat.as_background_repeat();
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatX, background_repeat.repeat_x(), document, true);
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatY, background_repeat.repeat_y(), document, true);
}
}
return;
}
if (value.is_background_repeat()) {
auto& background_repeat = value.as_background_repeat();
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatX, background_repeat.repeat_x(), document, true);
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatY, background_repeat.repeat_y(), document, true);
return;
}
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatX, value, document, true);
set_property_expanding_shorthands(style, PropertyID::BackgroundRepeatY, value, document, true);
return;
}
if (property_id == CSS::PropertyID::BackgroundRepeatX || property_id == CSS::PropertyID::BackgroundRepeatY) {
auto value_id = value.to_identifier();
if (value_id == CSS::ValueID::RepeatX || value_id == CSS::ValueID::RepeatY)
return;
style.set_property(property_id, 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);
}
StyleResolver::CustomPropertyResolutionTuple StyleResolver::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> StyleResolver::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 StyleResolver::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://drafts.csswg.org/css-cascade/#cascading
void StyleResolver::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.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 StyleResolver::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://drafts.csswg.org/css-cascade/#defaulting
void StyleResolver::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 StyleResolver::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->is_numeric()) {
int font_weight_integer = roundf(static_cast<NumericStyleValue const&>(*font_weight).value());
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 {
float root_font_size = 10;
if (element.document().document_element() != &element)
root_font_size = element.document().document_element()->layout_node()->font().presentation_size();
Gfx::FontMetrics font_metrics;
if (element.parent_element())
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.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()) {
auto calculated_size = maybe_length.value().to_px(viewport_rect, font_metrics, root_font_size);
if (calculated_size != 0)
size = calculated_size;
}
}
// 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 StyleResolver::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()) {
if (!it.value->is_length())
continue;
auto length = it.value->to_length();
if (length.is_relative()) {
auto px = length.relative_length_to_px(viewport_rect, font_metrics, root_font_size);
it.value = LengthStyleValue::create(CSS::Length::make_px(px));
}
}
}
NonnullRefPtr<StyleProperties> StyleResolver::resolve_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;
}
}
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