LibWeb: Implement VideoTrack and VideoTrackList

This implements the IDL for these types and some event handling around
them.

Userland/Libraries/LibWeb/HTML/VideoTrackList.cpp

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/Realm.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/VideoTrackListPrototype.h>
+#include <LibWeb/HTML/EventNames.h>
+#include <LibWeb/HTML/VideoTrackList.h>
+
+namespace Web::HTML {
+
+VideoTrackList::VideoTrackList(JS::Realm& realm)
+    : DOM::EventTarget(realm)
+    , m_video_tracks(realm.heap())
+{
+}
+
+JS::ThrowCompletionOr<void> VideoTrackList::initialize(JS::Realm& realm)
+{
+    MUST_OR_THROW_OOM(Base::initialize(realm));
+    set_prototype(&Bindings::ensure_web_prototype<Bindings::VideoTrackListPrototype>(realm, "VideoTrackList"));
+
+    return {};
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#dom-tracklist-item
+JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> VideoTrackList::internal_get_own_property(JS::PropertyKey const& property_name) const
+{
+    // To determine the value of an indexed property for a given index index in an AudioTrackList or VideoTrackList
+    // object list, the user agent must return the AudioTrack or VideoTrack object that represents the indexth track
+    // in list.
+    if (property_name.is_number()) {
+        if (auto index = property_name.as_number(); index < m_video_tracks.size()) {
+            JS::PropertyDescriptor descriptor;
+            descriptor.value = m_video_tracks.at(index);
+
+            return descriptor;
+        }
+    }
+
+    return Base::internal_get_own_property(property_name);
+}
+
+ErrorOr<void> VideoTrackList::add_track(Badge<HTMLMediaElement>, JS::NonnullGCPtr<VideoTrack> video_track)
+{
+    TRY(m_video_tracks.try_append(video_track));
+    video_track->set_video_track_list({}, this);
+
+    return {};
+}
+
+void VideoTrackList::remove_all_tracks(Badge<HTMLMediaElement>)
+{
+    m_video_tracks.clear();
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#dom-videotracklist-gettrackbyid
+JS::GCPtr<VideoTrack> VideoTrackList::get_track_by_id(StringView id) const
+{
+    // The AudioTrackList getTrackById(id) and VideoTrackList getTrackById(id) methods must return the first AudioTrack
+    // or VideoTrack object (respectively) in the AudioTrackList or VideoTrackList object (respectively) whose identifier
+    // is equal to the value of the id argument (in the natural order of the list, as defined above).
+    auto it = m_video_tracks.find_if([&](auto const& video_track) {
+        return video_track->id() == id;
+    });
+
+    // When no tracks match the given argument, the methods must return null.
+    if (it == m_video_tracks.end())
+        return nullptr;
+
+    return *it;
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#dom-videotracklist-selectedindex
+i32 VideoTrackList::selected_index() const
+{
+    // The VideoTrackList selectedIndex attribute must return the index of the currently selected track, if any.
+    auto it = m_video_tracks.find_if([&](auto const& video_track) {
+        return video_track->selected();
+    });
+
+    // If the VideoTrackList object does not currently represent any tracks, or if none of the tracks are selected,
+    // it must instead return −1.
+    if (it == m_video_tracks.end())
+        return -1;
+
+    return static_cast<i32>(it.index());
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onchange
+void VideoTrackList::set_onchange(WebIDL::CallbackType* event_handler)
+{
+    set_event_handler_attribute(HTML::EventNames::change, event_handler);
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onchange
+WebIDL::CallbackType* VideoTrackList::onchange()
+{
+    return event_handler_attribute(HTML::EventNames::change);
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onaddtrack
+void VideoTrackList::set_onaddtrack(WebIDL::CallbackType* event_handler)
+{
+    set_event_handler_attribute(HTML::EventNames::addtrack, event_handler);
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onaddtrack
+WebIDL::CallbackType* VideoTrackList::onaddtrack()
+{
+    return event_handler_attribute(HTML::EventNames::addtrack);
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onremovetrack
+void VideoTrackList::set_onremovetrack(WebIDL::CallbackType* event_handler)
+{
+    set_event_handler_attribute(HTML::EventNames::removetrack, event_handler);
+}
+
+// https://html.spec.whatwg.org/multipage/media.html#handler-tracklist-onremovetrack
+WebIDL::CallbackType* VideoTrackList::onremovetrack()
+{
+    return event_handler_attribute(HTML::EventNames::removetrack);
+}
+
+}