LibWeb: Parse the rotate css property

Author: https://github.com/stelar7 Commit: 488436fb54 Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1823 Reviewed-by: https://github.com/AtkinsSJ ✅
2025-07-31 05:09:12 +00:00 · 2024-10-16 08:50:35 +02:00 · 2024-10-16 08:50:35 +02:00 · 488436fb54 · 2024-10-29 14:41:49 +00:00
commit 488436fb54
parent 8ac60273a6
17 changed files with 284 additions and 0 deletions
--- a/Userland/Libraries/LibWeb/CSS/StyleValues/RotationStyleValue.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleValues/RotationStyleValue.cpp
@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2024, Steffen T. Larssen <dudedbz@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/String.h>
+#include <LibWeb/CSS/StyleValues/CSSMathValue.h>
+#include <LibWeb/CSS/StyleValues/NumberStyleValue.h>
+
+#include "RotationStyleValue.h"
+
+namespace Web::CSS {
+
+// https://www.w3.org/TR/2021/WD-css-transforms-2-20211109/#individual-transform-serialization
+String RotationStyleValue::to_string() const
+{
+    auto resolve_to_number = [](ValueComparingNonnullRefPtr<CSSStyleValue const> const& value) -> Optional<double> {
+        if (value->is_number())
+            return value->as_number().number();
+        if (value->is_math() && value->as_math().resolves_to_number())
+            return value->as_math().resolve_number();
+
+        VERIFY_NOT_REACHED();
+    };
+
+    auto x_value = resolve_to_number(m_properties.rotation_x).value_or(0);
+    auto y_value = resolve_to_number(m_properties.rotation_y).value_or(0);
+    auto z_value = resolve_to_number(m_properties.rotation_z).value_or(0);
+
+    // If the axis is parallel with the x or y axes, it must serialize as the appropriate keyword.
+    if (x_value > 0.0 && y_value == 0 && z_value == 0)
+        return MUST(String::formatted("x {}", m_properties.angle->to_string()));
+
+    if (x_value == 0 && y_value > 0.0 && z_value == 0)
+        return MUST(String::formatted("y {}", m_properties.angle->to_string()));
+
+    // If a rotation about the z axis (that is, in 2D) is specified, the property must serialize as just an <angle>.
+    if (x_value == 0 && y_value == 0 && z_value > 0.0)
+        return m_properties.angle->to_string();
+
+    // It must serialize as the keyword none if and only if none was originally specified.
+    // NOTE: This is handled by returning a keyword from the parser.
+
+    // If any other rotation is specified, the property must serialize with an axis specified.
+    return MUST(String::formatted("{} {} {} {}", m_properties.rotation_x->to_string(), m_properties.rotation_y->to_string(), m_properties.rotation_z->to_string(), m_properties.angle->to_string()));
+}
+
+}