LibWeb: Stub out a basic ResizeObserver interface

This patch establishes scaffolding for the ResizeObserver API.

Userland/Libraries/LibWeb/Bindings/WindowObjectHelper.h

@@ -233,6 +233,8 @@
 #include <LibWeb/Bindings/ProgressEventPrototype.h>
 #include <LibWeb/Bindings/RangeConstructor.h>
 #include <LibWeb/Bindings/RangePrototype.h>
+#include <LibWeb/Bindings/ResizeObserverConstructor.h>
+#include <LibWeb/Bindings/ResizeObserverPrototype.h>
 #include <LibWeb/Bindings/SVGElementConstructor.h>
 #include <LibWeb/Bindings/SVGElementPrototype.h>
 #include <LibWeb/Bindings/SVGGeometryElementConstructor.h>
@@ -395,6 +397,7 @@
     ADD_WINDOW_OBJECT_INTERFACE(ProcessingInstruction)     \
     ADD_WINDOW_OBJECT_INTERFACE(ProgressEvent)             \
     ADD_WINDOW_OBJECT_INTERFACE(Range)                     \
+    ADD_WINDOW_OBJECT_INTERFACE(ResizeObserver)            \
     ADD_WINDOW_OBJECT_INTERFACE(Screen)                    \
     ADD_WINDOW_OBJECT_INTERFACE(Selection)                 \
     ADD_WINDOW_OBJECT_INTERFACE(ShadowRoot)                \

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -244,6 +244,7 @@ set(SOURCES
     Painting/ShadowPainting.cpp
     Painting/StackingContext.cpp
     RequestIdleCallback/IdleDeadline.cpp
+    ResizeObserver/ResizeObserver.cpp
     SVG/AttributeNames.cpp
     SVG/SVGElement.cpp
     SVG/SVGGElement.cpp
@@ -472,6 +473,7 @@ libweb_js_wrapper(HTML/WebSocket)
 libweb_js_wrapper(HighResolutionTime/Performance)
 libweb_js_wrapper(NavigationTiming/PerformanceTiming)
 libweb_js_wrapper(RequestIdleCallback/IdleDeadline)
+libweb_js_wrapper(ResizeObserver/ResizeObserver)
 libweb_js_wrapper(SVG/SVGElement)
 libweb_js_wrapper(SVG/SVGGeometryElement)
 libweb_js_wrapper(SVG/SVGGraphicsElement)

Userland/Libraries/LibWeb/Forward.h

@@ -211,6 +211,10 @@ namespace Web::RequestIdleCallback {
 class IdleDeadline;
 }
 
+namespace Web::ResizeObserver {
+class ResizeObserver;
+}
+
 namespace Web::SVG {
 class SVGElement;
 class SVGGeometryElement;
@@ -396,6 +400,7 @@ class PerformanceTimingWrapper;
 class PerformanceWrapper;
 class ProcessingInstructionWrapper;
 class ProgressEventWrapper;
+class ResizeObserverWrapper;
 class ScreenWrapper;
 class ScriptExecutionContext;
 class SubmitEventWrapper;

Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/DOM/Element.h>
+#include <LibWeb/ResizeObserver/ResizeObserver.h>
+
+namespace Web::ResizeObserver {
+
+// https://drafts.csswg.org/resize-observer/#dom-resizeobserver-resizeobserver
+NonnullRefPtr<ResizeObserver> ResizeObserver::create_with_global_object(JS::GlobalObject& global_object, JS::Value callback)
+{
+    // FIXME: Implement
+    (void)global_object;
+    (void)callback;
+    return adopt_ref(*new ResizeObserver);
+}
+
+// https://drafts.csswg.org/resize-observer/#dom-resizeobserver-observe
+void ResizeObserver::observe(DOM::Element& target, ResizeObserverOptions options)
+{
+    // FIXME: Implement
+    (void)target;
+    (void)options;
+}
+
+// https://drafts.csswg.org/resize-observer/#dom-resizeobserver-unobserve
+void ResizeObserver::unobserve(DOM::Element& target)
+{
+    // FIXME: Implement
+    (void)target;
+}
+
+// https://drafts.csswg.org/resize-observer/#dom-resizeobserver-disconnect
+void ResizeObserver::disconnect()
+{
+    // FIXME: Implement
+}
+
+}

Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <LibWeb/Bindings/Wrappable.h>
+
+namespace Web::ResizeObserver {
+
+struct ResizeObserverOptions {
+    String box;
+};
+
+// https://drafts.csswg.org/resize-observer/#resize-observer-interface
+class ResizeObserver
+    : public RefCounted<ResizeObserver>
+    , public Bindings::Wrappable {
+public:
+    using WrapperType = Bindings::ResizeObserverWrapper;
+
+    static NonnullRefPtr<ResizeObserver> create_with_global_object(JS::GlobalObject&, JS::Value callback);
+
+    void observe(DOM::Element& target, ResizeObserverOptions);
+    void unobserve(DOM::Element& target);
+    void disconnect();
+};
+
+}

Userland/Libraries/LibWeb/ResizeObserver/ResizeObserver.idl

@@ -0,0 +1,17 @@
+[Exposed=(Window)]
+interface ResizeObserver {
+
+    // FIXME: This should be a ResizeObserverCallback.
+    constructor(any callback);
+    undefined observe(Element target, optional ResizeObserverOptions options = {});
+    undefined unobserve(Element target);
+    undefined disconnect();
+
+};
+
+dictionary ResizeObserverOptions {
+
+    // FIXME: This should be an enum.
+    DOMString box = "content-box";
+
+};