LibWeb: Add serialize_a_srgb_value()

This moves the logic from ColorStyleValue::to_string() to a standalone
function.

Userland/Libraries/LibWeb/CSS/Serialize.cpp

@@ -117,6 +117,18 @@ void serialize_a_url(StringBuilder& builder, StringView url)
     builder.append(')');
 }
 
+// https://www.w3.org/TR/css-color-4/#serializing-sRGB-values
+void serialize_a_srgb_value(StringBuilder& builder, Color color)
+{
+    // The serialized form is derived from the computed value and thus, uses either the rgb() or rgba() form
+    // (depending on whether the alpha is exactly 1, or not), with lowercase letters for the function name.
+    // NOTE: Since we use Gfx::Color, having an "alpha of 1" means its value is 255.
+    if (color.alpha() == 255)
+        builder.appendff("rgb({}, {}, {})"sv, color.red(), color.green(), color.blue());
+    else
+        builder.appendff("rgba({}, {}, {}, {})"sv, color.red(), color.green(), color.blue(), (float)(color.alpha()) / 255.0f);
+}
+
 String escape_a_character(u32 character)
 {
     StringBuilder builder;
@@ -152,4 +164,11 @@ String serialize_a_url(StringView url)
     return builder.to_string();
 }
 
+String serialize_a_srgb_value(Color color)
+{
+    StringBuilder builder;
+    serialize_a_srgb_value(builder, color);
+    return builder.to_string();
+}
+
 }

Userland/Libraries/LibWeb/CSS/Serialize.h

@@ -9,6 +9,7 @@
 #include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
+#include <LibGfx/Color.h>
 
 namespace Web::CSS {
 
@@ -17,11 +18,13 @@ void escape_a_character_as_code_point(StringBuilder&, u32 character);
 void serialize_an_identifier(StringBuilder&, StringView ident);
 void serialize_a_string(StringBuilder&, StringView string);
 void serialize_a_url(StringBuilder&, StringView url);
+void serialize_a_srgb_value(StringBuilder&, Color color);
 
 String escape_a_character(u32 character);
 String escape_a_character_as_code_point(u32 character);
 String serialize_an_identifier(StringView ident);
 String serialize_a_string(StringView string);
 String serialize_a_url(StringView url);
+String serialize_a_srgb_value(Color color);
 
 }

Userland/Libraries/LibWeb/CSS/StyleValue.cpp

@@ -1071,15 +1071,9 @@ CalculatedStyleValue::CalculationResult CalculatedStyleValue::CalcNumberSumPartW
     return value->resolve(layout_node, percentage_basis);
 }
 
-// https://www.w3.org/TR/css-color-4/#serializing-sRGB-values
 String ColorStyleValue::to_string() const
 {
-    // The serialized form is derived from the computed value and thus, uses either the rgb() or rgba() form
+    return serialize_a_srgb_value(m_color);
-    // (depending on whether the alpha is exactly 1, or not), with lowercase letters for the function name.
-    // NOTE: Since we use Gfx::Color, having an "alpha of 1" means its value is 255.
-    if (m_color.alpha() == 255)
-        return String::formatted("rgb({}, {}, {})", m_color.red(), m_color.green(), m_color.blue());
-    return String::formatted("rgba({}, {}, {}, {})", m_color.red(), m_color.green(), m_color.blue(), (float)(m_color.alpha()) / 255.0f);
 }
 
 bool ColorStyleValue::equals(StyleValue const& other) const