From 25c4c2397ec4482ea8cbcdf9fbcebd69823b58ac Mon Sep 17 00:00:00 2001
From: Sam Atkins <sam@ladybird.org>
Date: Wed, 13 Aug 2025 15:21:11 +0100
Subject: [PATCH] LibWeb/CSS: Add StyleValue getter to CSSStyleDeclarations

Will be used by StylePropertyMap, as that wants a StyleValue to reify,
not a string representation.
---
 Libraries/LibWeb/CSS/CSSDescriptors.cpp     |  8 ++++++++
 Libraries/LibWeb/CSS/CSSDescriptors.h       |  1 +
 Libraries/LibWeb/CSS/CSSStyleDeclaration.h  |  1 +
 Libraries/LibWeb/CSS/CSSStyleProperties.cpp | 10 ++++++++++
 Libraries/LibWeb/CSS/CSSStyleProperties.h   |  1 +
 5 files changed, 21 insertions(+)

diff --git a/Libraries/LibWeb/CSS/CSSDescriptors.cpp b/Libraries/LibWeb/CSS/CSSDescriptors.cpp
index e7415a93bee..5f7407d82e7 100644
--- a/Libraries/LibWeb/CSS/CSSDescriptors.cpp
+++ b/Libraries/LibWeb/CSS/CSSDescriptors.cpp
@@ -289,6 +289,14 @@ bool CSSDescriptors::has_property(StringView property_name) const
     return descriptor(*descriptor_id) != nullptr;
 }
 
+RefPtr<StyleValue const> CSSDescriptors::get_property_style_value(StringView property_name) const
+{
+    auto descriptor_id = descriptor_id_from_string(m_at_rule_id, property_name);
+    if (!descriptor_id.has_value())
+        return nullptr;
+    return descriptor(*descriptor_id);
+}
+
 bool is_shorthand(AtRuleID at_rule, DescriptorID descriptor)
 {
     if (at_rule == AtRuleID::Page && descriptor == DescriptorID::Margin)
diff --git a/Libraries/LibWeb/CSS/CSSDescriptors.h b/Libraries/LibWeb/CSS/CSSDescriptors.h
index 1da05ad8ddb..12ed30264eb 100644
--- a/Libraries/LibWeb/CSS/CSSDescriptors.h
+++ b/Libraries/LibWeb/CSS/CSSDescriptors.h
@@ -34,6 +34,7 @@ public:
     virtual WebIDL::ExceptionOr<void> set_css_text(StringView) override;
 
     virtual bool has_property(StringView property_name) const override;
+    virtual RefPtr<StyleValue const> get_property_style_value(StringView property_name) const override;
 
 protected:
     CSSDescriptors(JS::Realm&, AtRuleID, Vector<Descriptor>);
diff --git a/Libraries/LibWeb/CSS/CSSStyleDeclaration.h b/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
index 8f29294e46e..2504edb5ffe 100644
--- a/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
+++ b/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
@@ -58,6 +58,7 @@ public:
     void set_is_updating(bool value) { m_updating = value; }
 
     virtual bool has_property(StringView property_name) const = 0;
+    virtual RefPtr<StyleValue const> get_property_style_value(StringView property_name) const = 0;
 
 protected:
     enum class Computed : u8 {
diff --git a/Libraries/LibWeb/CSS/CSSStyleProperties.cpp b/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
index a03bf863c8d..63bd2df71b4 100644
--- a/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
+++ b/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
@@ -434,6 +434,16 @@ bool CSSStyleProperties::has_property(StringView property_name) const
     return get_property_internal(*property_id).has_value();
 }
 
+RefPtr<StyleValue const> CSSStyleProperties::get_property_style_value(StringView property_name) const
+{
+    auto property_id = property_id_from_string(property_name);
+    if (!property_id.has_value())
+        return nullptr;
+    if (auto style_property = get_property_internal(*property_id); style_property.has_value())
+        return style_property->value;
+    return nullptr;
+}
+
 // https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-getpropertyvalue
 Optional<StyleProperty> CSSStyleProperties::get_property_internal(PropertyID property_id) const
 {
diff --git a/Libraries/LibWeb/CSS/CSSStyleProperties.h b/Libraries/LibWeb/CSS/CSSStyleProperties.h
index 22f9be74f5b..b3ddd4b6878 100644
--- a/Libraries/LibWeb/CSS/CSSStyleProperties.h
+++ b/Libraries/LibWeb/CSS/CSSStyleProperties.h
@@ -50,6 +50,7 @@ public:
     size_t custom_property_count() const { return m_custom_properties.size(); }
 
     virtual bool has_property(StringView property_name) const override;
+    virtual RefPtr<StyleValue const> get_property_style_value(StringView property_name) const override;
 
     String css_float() const;
     WebIDL::ExceptionOr<void> set_css_float(StringView);