LibWeb/CSS: Implement CSSTransformComponent

This is a base type for the various transform functions.

CSSMatrixComponent's to_string() can throw exceptions, so to_string() is
implemented that way. https://github.com/w3c/fxtf-drafts/issues/611

+9 WPT subtests.

Libraries/LibWeb/CMakeLists.txt

@@ -142,6 +142,7 @@ set(SOURCES
     CSS/CSSStyleSheet.cpp
     CSS/CSSStyleValue.cpp
     CSS/CSSSupportsRule.cpp
+    CSS/CSSTransformComponent.cpp
     CSS/CSSTransition.cpp
     CSS/CSSUnitValue.cpp
     CSS/CSSUnparsedValue.cpp

Libraries/LibWeb/CSS/CSSTransformComponent.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "CSSTransformComponent.h"
+#include <LibWeb/Bindings/CSSTransformComponentPrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+
+namespace Web::CSS {
+
+GC_DEFINE_ALLOCATOR(CSSTransformComponent);
+
+CSSTransformComponent::CSSTransformComponent(JS::Realm& realm, Is2D is_2d)
+    : Bindings::PlatformObject(realm)
+    , m_is_2d(is_2d == Is2D::Yes)
+{
+}
+
+CSSTransformComponent::~CSSTransformComponent() = default;
+
+void CSSTransformComponent::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSTransformComponent);
+    Base::initialize(realm);
+}
+
+}

Libraries/LibWeb/CSS/CSSTransformComponent.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/PlatformObject.h>
+
+namespace Web::CSS {
+
+// https://drafts.css-houdini.org/css-typed-om-1/#csstransformcomponent
+class CSSTransformComponent : public Bindings::PlatformObject {
+    WEB_PLATFORM_OBJECT(CSSTransformComponent, Bindings::PlatformObject);
+    GC_DECLARE_ALLOCATOR(CSSTransformComponent);
+
+public:
+    enum class Is2D : u8 {
+        No,
+        Yes,
+    };
+
+    virtual void initialize(JS::Realm&) override;
+    virtual ~CSSTransformComponent() override;
+
+    virtual WebIDL::ExceptionOr<Utf16String> to_string() const = 0;
+
+    bool is_2d() const { return m_is_2d; }
+    virtual void set_is_2d(bool value) { m_is_2d = value; }
+
+    virtual WebIDL::ExceptionOr<GC::Ref<Geometry::DOMMatrix>> to_matrix() const = 0;
+
+protected:
+    explicit CSSTransformComponent(JS::Realm&, Is2D is_2d);
+
+private:
+    bool m_is_2d;
+};
+
+}

Libraries/LibWeb/CSS/CSSTransformComponent.idl

@@ -0,0 +1,9 @@
+#import <Geometry/DOMMatrix.idl>
+
+// https://drafts.css-houdini.org/css-typed-om-1/#csstransformcomponent
+[Exposed=(Window, Worker, PaintWorklet, LayoutWorklet)]
+interface CSSTransformComponent {
+    stringifier;
+    [ImplementedAs=is_2d] attribute boolean is2D;
+    DOMMatrix toMatrix();
+};

Libraries/LibWeb/Forward.h

@@ -267,6 +267,7 @@ class CSSStyleRule;
 class CSSStyleSheet;
 class CSSStyleValue;
 class CSSSupportsRule;
+class CSSTransformComponent;
 class CSSUnitValue;
 class CSSUnparsedValue;
 class CSSVariableReferenceValue;

Libraries/LibWeb/idl_files.cmake

@@ -62,6 +62,7 @@ libweb_js_bindings(CSS/CSSStyleRule)
 libweb_js_bindings(CSS/CSSStyleSheet)
 libweb_js_bindings(CSS/CSSStyleValue)
 libweb_js_bindings(CSS/CSSSupportsRule)
+libweb_js_bindings(CSS/CSSTransformComponent)
 libweb_js_bindings(CSS/CSSTransition)
 libweb_js_bindings(CSS/CSSUnitValue)
 libweb_js_bindings(CSS/CSSUnparsedValue)

Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp

@@ -58,6 +58,7 @@ static bool is_platform_object(Type const& type)
         "CSSNumericArray"sv,
         "CSSNumericValue"sv,
         "CSSStyleValue"sv,
+        "CSSTransformComponent"sv,
         "CSSUnitValue"sv,
         "CSSUnparsedValue"sv,
         "CSSVariableReferenceValue"sv,

Tests/LibWeb/Text/expected/all-window-properties.txt

@@ -74,6 +74,7 @@ CSSStyleRule
 CSSStyleSheet
 CSSStyleValue
 CSSSupportsRule
+CSSTransformComponent
 CSSTransition
 CSSUnitValue
 CSSUnparsedValue

Tests/LibWeb/Text/expected/wpt-import/css/css-typed-om/idlharness.txt

@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 545 tests
 
-287 Pass
+296 Pass
-258 Fail
+249 Fail
 Pass	idl_test setup
 Pass	idl_test validation
 Pass	Partial interface Element: original interface defined
@@ -267,15 +267,15 @@ Pass	CSSStyleValue interface: transformValue must inherit property "parse(USVStr
 Pass	CSSStyleValue interface: calling parse(USVString, USVString) on transformValue with too few arguments must throw TypeError
 Pass	CSSStyleValue interface: transformValue must inherit property "parseAll(USVString, USVString)" with the proper type
 Pass	CSSStyleValue interface: calling parseAll(USVString, USVString) on transformValue with too few arguments must throw TypeError
-Fail	CSSTransformComponent interface: existence and properties of interface object
+Pass	CSSTransformComponent interface: existence and properties of interface object
-Fail	CSSTransformComponent interface object length
+Pass	CSSTransformComponent interface object length
-Fail	CSSTransformComponent interface object name
+Pass	CSSTransformComponent interface object name
-Fail	CSSTransformComponent interface: existence and properties of interface prototype object
+Pass	CSSTransformComponent interface: existence and properties of interface prototype object
-Fail	CSSTransformComponent interface: existence and properties of interface prototype object's "constructor" property
+Pass	CSSTransformComponent interface: existence and properties of interface prototype object's "constructor" property
-Fail	CSSTransformComponent interface: existence and properties of interface prototype object's @@unscopables property
+Pass	CSSTransformComponent interface: existence and properties of interface prototype object's @@unscopables property
-Fail	CSSTransformComponent interface: stringifier
+Pass	CSSTransformComponent interface: stringifier
-Fail	CSSTransformComponent interface: attribute is2D
+Pass	CSSTransformComponent interface: attribute is2D
-Fail	CSSTransformComponent interface: operation toMatrix()
+Pass	CSSTransformComponent interface: operation toMatrix()
 Fail	CSSTranslate interface: existence and properties of interface object
 Fail	CSSTranslate interface object length
 Fail	CSSTranslate interface object name