LibWeb/CSS: Implement CSSImageValue and reify images as it

This is specced to be opaque, so there's not much to it.

Libraries/LibWeb/CMakeLists.txt

@@ -110,6 +110,7 @@ set(SOURCES
     CSS/CSSFontFaceDescriptors.cpp
     CSS/CSSFontFaceRule.cpp
     CSS/CSSGroupingRule.cpp
+    CSS/CSSImageValue.cpp
     CSS/CSSImportRule.cpp
     CSS/CSSKeyframeRule.cpp
     CSS/CSSKeyframesRule.cpp
@@ -206,6 +207,7 @@ set(SOURCES
     CSS/StyleSheet.cpp
     CSS/StyleSheetIdentifier.cpp
     CSS/StyleSheetList.cpp
+    CSS/StyleValues/AbstractImageStyleValue.cpp
     CSS/StyleValues/AnchorStyleValue.cpp
     CSS/StyleValues/AnchorSizeStyleValue.cpp
     CSS/StyleValues/AngleStyleValue.cpp

Libraries/LibWeb/CSS/CSSImageValue.cpp

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "CSSImageValue.h"
+#include <LibWeb/Bindings/CSSImageValuePrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+
+namespace Web::CSS {
+
+GC_DEFINE_ALLOCATOR(CSSImageValue);
+
+GC::Ref<CSSImageValue> CSSImageValue::create(JS::Realm& realm, String constructed_from_string)
+{
+    return realm.create<CSSImageValue>(realm, move(constructed_from_string));
+}
+
+CSSImageValue::CSSImageValue(JS::Realm& realm, String constructed_from_string)
+    : CSSStyleValue(realm)
+    , m_constructed_from_string(move(constructed_from_string))
+{
+}
+
+void CSSImageValue::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSImageValue);
+    Base::initialize(realm);
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#stylevalue-serialization
+String CSSImageValue::to_string() const
+{
+    // AD-HOC: The spec doesn't say how to serialize this, as it's intentionally a black box.
+    //         We just serialize the source string that was used to construct this.
+    return m_constructed_from_string;
+}
+
+}

Libraries/LibWeb/CSS/CSSImageValue.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/CSS/CSSStyleValue.h>
+
+namespace Web::CSS {
+
+// https://drafts.css-houdini.org/css-typed-om-1/#cssimagevalue
+class CSSImageValue final : public CSSStyleValue {
+    WEB_PLATFORM_OBJECT(CSSImageValue, CSSStyleValue);
+    GC_DECLARE_ALLOCATOR(CSSImageValue);
+
+public:
+    [[nodiscard]] static GC::Ref<CSSImageValue> create(JS::Realm&, String constructed_from_string);
+
+    virtual ~CSSImageValue() override = default;
+
+    virtual String to_string() const override;
+
+private:
+    explicit CSSImageValue(JS::Realm&, String constructed_from_string);
+
+    virtual void initialize(JS::Realm&) override;
+
+    String m_constructed_from_string;
+};
+
+}

Libraries/LibWeb/CSS/CSSImageValue.idl

@@ -0,0 +1,6 @@
+#import <CSS/CSSStyleValue.idl>
+
+// https://drafts.css-houdini.org/css-typed-om-1/#cssimagevalue
+[Exposed=(Window, Worker, PaintWorklet, LayoutWorklet)]
+interface CSSImageValue : CSSStyleValue {
+};

Libraries/LibWeb/CSS/StyleValues/AbstractImageStyleValue.cpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "AbstractImageStyleValue.h"
+#include <LibWeb/CSS/CSSImageValue.h>
+
+namespace Web::CSS {
+
+// https://drafts.css-houdini.org/css-typed-om-1/#reify-stylevalue
+GC::Ref<CSSStyleValue> AbstractImageStyleValue::reify(JS::Realm& realm, String const&) const
+{
+    // AD-HOC: There's no spec description of how to reify as a CSSImageValue.
+    return CSSImageValue::create(realm, to_string(SerializationMode::Normal));
+}
+
+}

Libraries/LibWeb/CSS/StyleValues/AbstractImageStyleValue.h

@@ -40,6 +40,8 @@ public:
     virtual void paint(DisplayListRecordingContext& context, DevicePixelRect const& dest_rect, ImageRendering) const = 0;
 
     virtual Optional<Gfx::Color> color_if_single_pixel_bitmap() const { return {}; }
+
+    virtual GC::Ref<CSSStyleValue> reify(JS::Realm&, String const& associated_property) const override;
 };
 
 // And now, some gradient related things. Maybe these should live somewhere else.

Libraries/LibWeb/Forward.h

@@ -235,6 +235,7 @@ class CSSDescriptors;
 class CSSFontFaceDescriptors;
 class CSSFontFaceRule;
 class CSSGroupingRule;
+class CSSImageValue;
 class CSSImportRule;
 class CSSKeyframeRule;
 class CSSKeyframesRule;

Libraries/LibWeb/idl_files.cmake

@@ -29,6 +29,7 @@ libweb_js_bindings(CSS/CSSCounterStyleRule)
 libweb_js_bindings(CSS/CSSFontFaceDescriptors)
 libweb_js_bindings(CSS/CSSFontFaceRule)
 libweb_js_bindings(CSS/CSSGroupingRule)
+libweb_js_bindings(CSS/CSSImageValue)
 libweb_js_bindings(CSS/CSSImportRule)
 libweb_js_bindings(CSS/CSSKeyframeRule)
 libweb_js_bindings(CSS/CSSKeyframesRule)

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

@@ -42,6 +42,7 @@ CSSCounterStyleRule
 CSSFontFaceDescriptors
 CSSFontFaceRule
 CSSGroupingRule
+CSSImageValue
 CSSImportRule
 CSSKeyframeRule
 CSSKeyframesRule

Tests/LibWeb/Text/expected/wpt-import/css/css-typed-om/stylevalue-normalization/normalize-image.txt

@@ -2,7 +2,7 @@ Harness status: OK
 
 Found 3 tests
 
-3 Fail
+3 Pass
-Fail	Normalizing a valid <url> returns a CSSImageValue
+Pass	Normalizing a valid <url> returns a CSSImageValue
-Fail	Normalizing a bad <url> returns a CSSImageValue
+Pass	Normalizing a bad <url> returns a CSSImageValue
-Fail	Normalizing a <gradient> returns a CSSImageValue
+Pass	Normalizing a <gradient> returns a CSSImageValue