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LibWeb: Account for animated values when computing font #6757

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884426a
LibWeb: Simplify handling of `font-variation-settings`
Calme1709 Nov 6, 2025
a86e5a4
LibWeb: Separate font computation logic from StyleComputer
Calme1709 Nov 6, 2025
fd1b97e
LibWeb: Account for animated values when computing font
Calme1709 Nov 8, 2025
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1 change: 1 addition & 0 deletions Libraries/LibWeb/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,7 @@ set(SOURCES
CSS/EdgeRect.cpp
CSS/Fetch.cpp
CSS/Flex.cpp
CSS/FontComputer.cpp
CSS/FontFace.cpp
CSS/FontFaceSet.cpp
CSS/Frequency.cpp
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5 changes: 3 additions & 2 deletions Libraries/LibWeb/CSS/CSSStyleSheet.cpp
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Expand Up @@ -11,6 +11,7 @@
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/CSSImportRule.h>
#include <LibWeb/CSS/CSSStyleSheet.h>
#include <LibWeb/CSS/FontComputer.h>
#include <LibWeb/CSS/Parser/Parser.h>
#include <LibWeb/CSS/StyleComputer.h>
#include <LibWeb/CSS/StyleSheetList.h>
Expand Down Expand Up @@ -325,7 +326,7 @@ void CSSStyleSheet::add_owning_document_or_shadow_root(DOM::Node& document_or_sh
// All owning documents or shadow roots must be part of the same document so we only need to load this style
// sheet's fonts against the document of the first
if (this->owning_documents_or_shadow_roots().size() == 1)
document_or_shadow_root.document().style_computer().load_fonts_from_sheet(*this);
document_or_shadow_root.document().font_computer().load_fonts_from_sheet(*this);

for (auto const& import_rule : m_import_rules) {
if (import_rule->loaded_style_sheet())
Expand All @@ -340,7 +341,7 @@ void CSSStyleSheet::remove_owning_document_or_shadow_root(DOM::Node& document_or
// All owning documents or shadow roots must be part of the same document so we only need to unload this style
// sheet's fonts once we have none remaining.
if (this->owning_documents_or_shadow_roots().size() == 0)
document_or_shadow_root.document().style_computer().unload_fonts_from_sheet(*this);
document_or_shadow_root.document().font_computer().unload_fonts_from_sheet(*this);

for (auto const& import_rule : m_import_rules) {
if (import_rule->loaded_style_sheet())
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50 changes: 46 additions & 4 deletions Libraries/LibWeb/CSS/ComputedProperties.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <LibGC/CellAllocator.h>
#include <LibWeb/CSS/Clip.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/FontComputer.h>
#include <LibWeb/CSS/StyleValues/ColorSchemeStyleValue.h>
#include <LibWeb/CSS/StyleValues/ContentStyleValue.h>
#include <LibWeb/CSS/StyleValues/CounterDefinitionsStyleValue.h>
Expand Down Expand Up @@ -47,6 +48,21 @@ namespace Web::CSS {

GC_DEFINE_ALLOCATOR(ComputedProperties);

static HashTable<PropertyID> font_affecting_properties()
{
static HashTable<PropertyID> font_affecting_properties;
if (font_affecting_properties.is_empty()) {
font_affecting_properties.set(PropertyID::FontFamily);
font_affecting_properties.set(PropertyID::FontSize);
font_affecting_properties.set(PropertyID::FontStyle);
font_affecting_properties.set(PropertyID::FontWeight);
font_affecting_properties.set(PropertyID::FontWidth);
font_affecting_properties.set(PropertyID::FontVariationSettings);
}

return font_affecting_properties;
}
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@gmta gmta Nov 20, 2025

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Do we need a HashTable for this fixed set of properties? I suspect first_is_one_of(property_id, ...) is just as fast when dealing with a small set, and does not allocate.


ComputedProperties::ComputedProperties() = default;

ComputedProperties::~ComputedProperties() = default;
Expand Down Expand Up @@ -128,6 +144,9 @@ void ComputedProperties::set_property_without_modifying_flags(PropertyID id, Non
VERIFY(id >= first_longhand_property_id && id <= last_longhand_property_id);

m_property_values[to_underlying(id) - to_underlying(first_longhand_property_id)] = move(value);

if (font_affecting_properties().contains(id))
clear_computed_font_list_cache();
}

void ComputedProperties::revert_property(PropertyID id, ComputedProperties const& style_for_revert)
Expand All @@ -153,6 +172,9 @@ void ComputedProperties::set_animated_property(PropertyID id, NonnullRefPtr<Styl
{
m_animated_property_values.set(id, move(value));
set_animated_property_inherited(id, inherited);

if (font_affecting_properties().contains(id))
clear_computed_font_list_cache();
}

void ComputedProperties::remove_animated_property(PropertyID id)
Expand All @@ -175,7 +197,7 @@ StyleValue const& ComputedProperties::property(PropertyID property_id, WithAnima
return *animated_value.value();
}

// By the time we call this method, all properties have values assigned.
// By the time we call this method, the property should have been assigned
return *m_property_values[to_underlying(property_id) - to_underlying(first_longhand_property_id)];
}

Expand Down Expand Up @@ -1901,7 +1923,7 @@ HashMap<StringView, u8> ComputedProperties::font_feature_settings() const
return {};
}

Optional<HashMap<FlyString, NumberOrCalculated>> ComputedProperties::font_variation_settings() const
HashMap<FlyString, double> ComputedProperties::font_variation_settings() const
{
auto const& value = property(PropertyID::FontVariationSettings);

Expand All @@ -1910,7 +1932,7 @@ Optional<HashMap<FlyString, NumberOrCalculated>> ComputedProperties::font_variat

if (value.is_value_list()) {
auto const& axis_tags = value.as_value_list().values();
HashMap<FlyString, NumberOrCalculated> result;
HashMap<FlyString, double> result;
result.ensure_capacity(axis_tags.size());
for (auto const& tag_value : axis_tags) {
auto const& axis_tag = tag_value->as_open_type_tagged();
Expand All @@ -1919,7 +1941,7 @@ Optional<HashMap<FlyString, NumberOrCalculated>> ComputedProperties::font_variat
result.set(axis_tag.tag(), axis_tag.value()->as_number().number());
} else {
VERIFY(axis_tag.value()->is_calculated());
result.set(axis_tag.tag(), NumberOrCalculated { axis_tag.value()->as_calculated() });
result.set(axis_tag.tag(), axis_tag.value()->as_calculated().resolve_number({}).value());
}
}
return result;
Expand Down Expand Up @@ -2517,6 +2539,26 @@ WillChange ComputedProperties::will_change() const
return WillChange::make_auto();
}

ValueComparingNonnullRefPtr<Gfx::FontCascadeList const> ComputedProperties::computed_font_list(FontComputer const& font_computer) const
{
if (!m_cached_computed_font_list) {
const_cast<ComputedProperties*>(this)->m_cached_computed_font_list = font_computer.compute_font_for_style_values(property(PropertyID::FontFamily), font_size(), font_slope(), font_weight(), font_width(), font_variation_settings());
VERIFY(!m_cached_computed_font_list->is_empty());
}

return *m_cached_computed_font_list;
}

ValueComparingNonnullRefPtr<Gfx::Font const> ComputedProperties::first_available_computed_font(FontComputer const& font_computer) const
{
if (!m_cached_first_available_computed_font)
// https://drafts.csswg.org/css-fonts/#first-available-font
// First font for which the character U+0020 (space) is not excluded by a unicode-range
const_cast<ComputedProperties*>(this)->m_cached_first_available_computed_font = computed_font_list(font_computer)->font_for_code_point(' ');

return *m_cached_first_available_computed_font;
}

CSSPixels ComputedProperties::font_size() const
{
return property(PropertyID::FontSize).as_length().length().absolute_length_to_px();
Expand Down
34 changes: 12 additions & 22 deletions Libraries/LibWeb/CSS/ComputedProperties.h
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Expand Up @@ -161,7 +161,7 @@ class WEB_API ComputedProperties final : public JS::Cell {
FontKerning font_kerning() const;
Optional<FlyString> font_language_override() const;
HashMap<StringView, u8> font_feature_settings() const;
Optional<HashMap<FlyString, NumberOrCalculated>> font_variation_settings() const;
HashMap<FlyString, double> font_variation_settings() const;
GridTrackSizeList grid_auto_columns() const;
GridTrackSizeList grid_auto_rows() const;
GridTrackSizeList grid_template_columns() const;
Expand Down Expand Up @@ -228,25 +228,9 @@ class WEB_API ComputedProperties final : public JS::Cell {

WillChange will_change() const;

Gfx::FontCascadeList const& computed_font_list() const
{
VERIFY(m_font_list);
return *m_font_list;
}

Gfx::Font const& first_available_computed_font() const
{
VERIFY(m_first_available_computed_font);
return *m_first_available_computed_font;
}

void set_computed_font_list(NonnullRefPtr<Gfx::FontCascadeList const> font_list)
{
m_font_list = move(font_list);
// https://drafts.csswg.org/css-fonts/#first-available-font
// First font for which the character U+0020 (space) is not excluded by a unicode-range
m_first_available_computed_font = m_font_list->font_for_code_point(' ');
}
ValueComparingRefPtr<Gfx::FontCascadeList const> cached_computed_font_list() const { return m_cached_computed_font_list; }
ValueComparingNonnullRefPtr<Gfx::FontCascadeList const> computed_font_list(FontComputer const&) const;
ValueComparingNonnullRefPtr<Gfx::Font const> first_available_computed_font(FontComputer const&) const;

[[nodiscard]] CSSPixels line_height() const;
[[nodiscard]] CSSPixels font_size() const;
Expand Down Expand Up @@ -300,8 +284,14 @@ class WEB_API ComputedProperties final : public JS::Cell {
Display m_display_before_box_type_transformation { InitialValues::display() };

int m_math_depth { InitialValues::math_depth() };
RefPtr<Gfx::FontCascadeList const> m_font_list;
RefPtr<Gfx::Font const> m_first_available_computed_font;

RefPtr<Gfx::FontCascadeList const> m_cached_computed_font_list;
RefPtr<Gfx::Font const> m_cached_first_available_computed_font;
void clear_computed_font_list_cache()
{
m_cached_computed_font_list = nullptr;
m_cached_first_available_computed_font = nullptr;
}

Optional<CSSPixels> m_line_height;

Expand Down
6 changes: 3 additions & 3 deletions Libraries/LibWeb/CSS/ComputedValues.h
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Expand Up @@ -645,7 +645,7 @@ class ComputedValues {
double font_weight() const { return m_inherited.font_weight; }
Gfx::ShapeFeatures font_features() const { return m_inherited.font_features; }
Optional<FlyString> font_language_override() const { return m_inherited.font_language_override; }
Optional<HashMap<FlyString, NumberOrCalculated>> font_variation_settings() const { return m_inherited.font_variation_settings; }
HashMap<FlyString, double> font_variation_settings() const { return m_inherited.font_variation_settings; }
CSSPixels line_height() const { return m_inherited.line_height; }
Time transition_delay() const { return m_noninherited.transition_delay; }

Expand Down Expand Up @@ -682,7 +682,7 @@ class ComputedValues {
double font_weight { InitialValues::font_weight() };
Gfx::ShapeFeatures font_features { InitialValues::font_features() };
Optional<FlyString> font_language_override;
Optional<HashMap<FlyString, NumberOrCalculated>> font_variation_settings;
HashMap<FlyString, double> font_variation_settings;
CSSPixels line_height { InitialValues::line_height() };
BorderCollapse border_collapse { InitialValues::border_collapse() };
EmptyCells empty_cells { InitialValues::empty_cells() };
Expand Down Expand Up @@ -887,7 +887,7 @@ class MutableComputedValues final : public ComputedValues {
void set_font_weight(double font_weight) { m_inherited.font_weight = font_weight; }
void set_font_features(Gfx::ShapeFeatures font_features) { m_inherited.font_features = move(font_features); }
void set_font_language_override(Optional<FlyString> font_language_override) { m_inherited.font_language_override = move(font_language_override); }
void set_font_variation_settings(Optional<HashMap<FlyString, NumberOrCalculated>> value) { m_inherited.font_variation_settings = move(value); }
void set_font_variation_settings(HashMap<FlyString, double> value) { m_inherited.font_variation_settings = move(value); }
void set_line_height(CSSPixels line_height) { m_inherited.line_height = line_height; }
void set_border_spacing_horizontal(Length border_spacing_horizontal) { m_inherited.border_spacing_horizontal = move(border_spacing_horizontal); }
void set_border_spacing_vertical(Length border_spacing_vertical) { m_inherited.border_spacing_vertical = move(border_spacing_vertical); }
Expand Down
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