LibWeb: Support individual scale CSS property

Author: https://github.com/awesomekling
Commit: 9a7c9286c4
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2506
Reviewed-by: https://github.com/shannonbooth

Libraries/LibWeb/CSS/StyleValues/ScaleStyleValue.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/String.h>
+#include <LibWeb/CSS/StyleValues/ScaleStyleValue.h>
+
+namespace Web::CSS {
+
+// https://www.w3.org/TR/2021/WD-css-transforms-2-20211109/#individual-transform-serialization
+String ScaleStyleValue::to_string() const
+{
+    auto resolve_to_string = [](NumberPercentage const& value) -> String {
+        if (value.is_number()) {
+            return MUST(String::formatted("{}", value.number().value()));
+        }
+        if (value.is_percentage()) {
+            return MUST(String::formatted("{}", value.percentage().value() / 100.0));
+        }
+        return value.to_string();
+    };
+
+    auto x_value = resolve_to_string(m_properties.x);
+    auto y_value = resolve_to_string(m_properties.y);
+
+    StringBuilder builder;
+    builder.append(x_value);
+    if (x_value != y_value) {
+        builder.append(" "sv);
+        builder.append(y_value);
+    }
+    return builder.to_string_without_validation();
+}
+
+}

Libraries/LibWeb/CSS/StyleValues/ScaleStyleValue.h

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+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/CSS/CSSStyleValue.h>
+#include <LibWeb/CSS/PercentageOr.h>
+
+namespace Web::CSS {
+
+class ScaleStyleValue : public StyleValueWithDefaultOperators<ScaleStyleValue> {
+public:
+    static ValueComparingNonnullRefPtr<ScaleStyleValue> create(NumberPercentage x, NumberPercentage y)
+    {
+        return adopt_ref(*new (nothrow) ScaleStyleValue(move(x), move(y)));
+    }
+
+    virtual ~ScaleStyleValue() override = default;
+
+    NumberPercentage const& x() const { return m_properties.x; }
+    NumberPercentage const& y() const { return m_properties.y; }
+
+    virtual String to_string() const override;
+
+    bool properties_equal(ScaleStyleValue const& other) const { return m_properties == other.m_properties; }
+
+private:
+    explicit ScaleStyleValue(
+        NumberPercentage x,
+        NumberPercentage y)
+        : StyleValueWithDefaultOperators(Type::Scale)
+        , m_properties {
+            .x = move(x),
+            .y = move(y),
+        }
+    {
+    }
+
+    struct Properties {
+        NumberPercentage x;
+        NumberPercentage y;
+        bool operator==(Properties const&) const = default;
+    } m_properties;
+};
+
+}