LibWeb: Add stub implementation of FontFaceSet and Document.fonts

This is now enough for duolingo to load and use its fallback fonts.

Userland/Libraries/LibWeb/CSS/FontFaceSet.cpp

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Heap/Heap.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Bindings/FontFaceSetPrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/CSS/FontFaceSet.h>
+#include <LibWeb/WebIDL/Promise.h>
+
+namespace Web::CSS {
+
+JS_DEFINE_ALLOCATOR(FontFaceSet);
+
+JS::NonnullGCPtr<FontFaceSet> FontFaceSet::construct_impl(JS::Realm& realm, Vector<JS::Handle<FontFace>> initial_faces)
+{
+    return realm.heap().allocate<FontFaceSet>(realm, realm, move(initial_faces));
+}
+
+JS::NonnullGCPtr<FontFaceSet> FontFaceSet::create(JS::Realm& realm)
+{
+    return construct_impl(realm, {});
+}
+
+FontFaceSet::FontFaceSet(JS::Realm& realm, Vector<JS::Handle<FontFace>>)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+void FontFaceSet::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(FontFaceSet);
+}
+
+// https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-add
+JS::NonnullGCPtr<FontFaceSet> FontFaceSet::add(JS::Handle<FontFace>)
+{
+    // FIXME: Do the steps
+    return *this;
+}
+
+// https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-load
+JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Promise>> FontFaceSet::load(String const&, String const&)
+{
+    // FIXME: Do the steps
+    auto promise = WebIDL::create_rejected_promise(realm(), WebIDL::NotSupportedError::create(realm(), "FontFaceSet::load is not yet implemented"_fly_string));
+    return verify_cast<JS::Promise>(*promise->promise());
+}
+
+}

Userland/Libraries/LibWeb/CSS/FontFaceSet.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/CSS/FontFace.h>
+
+namespace Web::CSS {
+
+class FontFaceSet final : public Bindings::PlatformObject {
+    WEB_PLATFORM_OBJECT(FontFace, Bindings::PlatformObject);
+    JS_DECLARE_ALLOCATOR(FontFaceSet);
+
+public:
+    [[nodiscard]] static JS::NonnullGCPtr<FontFaceSet> construct_impl(JS::Realm&, Vector<JS::Handle<FontFace>> initial_faces);
+    [[nodiscard]] static JS::NonnullGCPtr<FontFaceSet> create(JS::Realm&);
+    virtual ~FontFaceSet() override = default;
+
+    JS::NonnullGCPtr<FontFaceSet> add(JS::Handle<FontFace> face);
+    JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Promise>> load(String const& font, String const& text);
+
+private:
+    FontFaceSet(JS::Realm&, Vector<JS::Handle<FontFace>> initial_faces);
+
+    virtual void initialize(JS::Realm&) override;
+};
+
+}

Userland/Libraries/LibWeb/CSS/FontFaceSet.idl

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+#import <CSS/FontFace.idl>
+
+dictionary FontFaceSetLoadEventInit : EventInit {
+    sequence<FontFace> fontfaces = [];
+};
+
+// FIXME
+// [Exposed=(Window,Worker)]
+//interface FontFaceSetLoadEvent : Event {
+//    constructor(CSSOMString type, optional FontFaceSetLoadEventInit eventInitDict = {});
+//    [SameObject] readonly attribute FrozenArray<FontFace> fontfaces;
+//};
+
+enum FontFaceSetLoadStatus { "loading", "loaded" };
+
+// https://drafts.csswg.org/css-font-loading/#fontfaceset
+[Exposed=(Window,Worker)]
+interface FontFaceSet : EventTarget {
+    constructor(sequence<FontFace> initialFaces);
+
+    // FIXME: setlike<FontFace>;
+    FontFaceSet add(FontFace font);
+    // FIXME: boolean delete(FontFace font);
+    // FIXME:  clear();
+
+    // events for when loading state changes
+    // FIXME: attribute EventHandler onloading;
+    // FIXME: attribute EventHandler onloadingdone;
+    // FIXME: attribute EventHandler onloadingerror;
+
+    // check and start loads if appropriate
+    // and fulfill promise when all loads complete
+    // FIXME: Promise<sequence<FontFace>> load(CSSOMString font, optional CSSOMString text = " ");
+    Promise<sequence<FontFace>> load(CSSOMString font, optional CSSOMString text = "");
+
+    // return whether all fonts in the fontlist are loaded
+    // (does not initiate load if not available)
+    // FIXME: boolean check(CSSOMString font, optional CSSOMString text = " ");
+
+    // async notification that font loading and layout operations are done
+    // FIXME: readonly attribute Promise<FontFaceSet> ready;
+
+    // loading state, "loading" while one or more fonts loading, "loaded" otherwise
+    // FIXME: readonly attribute FontFaceSetLoadStatus status;
+};
+
+interface mixin FontFaceSource {
+    readonly attribute FontFaceSet fonts;
+};