LibWeb/WebAudio: Fire complete event with OfflineAudioCompletionEvent

Author: https://github.com/Lubrsi
Commit: 47b512ec56
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6860

Libraries/LibWeb/WebAudio/OfflineAudioCompletionEvent.cpp

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/OfflineAudioCompletionEventPrototype.h>
+#include <LibWeb/WebAudio/OfflineAudioCompletionEvent.h>
+
+namespace Web::WebAudio {
+
+GC_DEFINE_ALLOCATOR(OfflineAudioCompletionEvent);
+
+WebIDL::ExceptionOr<GC::Ref<OfflineAudioCompletionEvent>> OfflineAudioCompletionEvent::construct_impl(JS::Realm& realm, FlyString const& event_name, OfflineAudioCompletionEventInit const& event_init)
+{
+    return realm.create<OfflineAudioCompletionEvent>(realm, event_name, event_init);
+}
+
+OfflineAudioCompletionEvent::OfflineAudioCompletionEvent(JS::Realm& realm, FlyString const& event_name, OfflineAudioCompletionEventInit const& event_init)
+    : DOM::Event(realm, event_name, event_init)
+    , m_rendered_buffer(event_init.rendered_buffer)
+{
+}
+
+OfflineAudioCompletionEvent::~OfflineAudioCompletionEvent() = default;
+
+void OfflineAudioCompletionEvent::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(OfflineAudioCompletionEvent);
+    Base::initialize(realm);
+}
+
+void OfflineAudioCompletionEvent::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_rendered_buffer);
+}
+
+}

Libraries/LibWeb/WebAudio/OfflineAudioCompletionEvent.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2025, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/DOM/Event.h>
+#include <LibWeb/WebAudio/AudioBuffer.h>
+
+namespace Web::WebAudio {
+
+struct OfflineAudioCompletionEventInit : public DOM::EventInit {
+    GC::Ptr<AudioBuffer> rendered_buffer;
+};
+
+class OfflineAudioCompletionEvent final : public DOM::Event {
+    WEB_PLATFORM_OBJECT(OfflineAudioCompletionEvent, DOM::Event);
+    GC_DECLARE_ALLOCATOR(OfflineAudioCompletionEvent);
+
+public:
+    static WebIDL::ExceptionOr<GC::Ref<OfflineAudioCompletionEvent>> construct_impl(JS::Realm&, FlyString const& event_name, OfflineAudioCompletionEventInit const& event_init);
+
+    virtual ~OfflineAudioCompletionEvent() override;
+
+    GC::Ptr<AudioBuffer> rendered_buffer() const { return m_rendered_buffer; }
+
+private:
+    OfflineAudioCompletionEvent(JS::Realm&, FlyString const& event_name, OfflineAudioCompletionEventInit const& event_init);
+
+    void initialize(JS::Realm&) override;
+
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    GC::Ptr<AudioBuffer> m_rendered_buffer;
+};
+
+}

Libraries/LibWeb/WebAudio/OfflineAudioCompletionEvent.idl

@@ -0,0 +1,14 @@
+#import <DOM/Event.idl>
+#import <WebAudio/AudioBuffer.idl>
+
+// https://webaudio.github.io/web-audio-api/#OfflineAudioCompletionEvent
+[Exposed=Window]
+interface OfflineAudioCompletionEvent : Event {
+    constructor(DOMString type, OfflineAudioCompletionEventInit eventInitDict);
+    readonly attribute AudioBuffer renderedBuffer;
+};
+
+// https://webaudio.github.io/web-audio-api/#OfflineAudioCompletionEventInit
+dictionary OfflineAudioCompletionEventInit : EventInit {
+    required AudioBuffer renderedBuffer;
+};

Libraries/LibWeb/WebAudio/OfflineAudioContext.cpp

@@ -13,6 +13,7 @@
 #include <LibWeb/HTML/Window.h>
 #include <LibWeb/WebAudio/AudioBuffer.h>
 #include <LibWeb/WebAudio/AudioDestinationNode.h>
+#include <LibWeb/WebAudio/OfflineAudioCompletionEvent.h>
 #include <LibWeb/WebAudio/OfflineAudioContext.h>
 
 namespace Web::WebAudio {
@@ -138,9 +139,17 @@ void OfflineAudioContext::begin_offline_rendering(GC::Ref<WebIDL::Promise> promi
 
         // 4.2: Queue a media element task to fire an event named complete at the OfflineAudioContext using OfflineAudioCompletionEvent
         //      whose renderedBuffer property is set to [[rendered buffer]].
-        // FIXME: Need to implement OfflineAudioCompletionEvent.
         queue_a_media_element_task(GC::create_function(heap(), [&realm, this]() {
-            this->dispatch_event(DOM::Event::create(realm, HTML::EventNames::complete));
+            auto event_init = OfflineAudioCompletionEventInit {
+                {
+                    .bubbles = false,
+                    .cancelable = false,
+                    .composed = false,
+                },
+                this->m_rendered_buffer,
+            };
+            auto event = MUST(OfflineAudioCompletionEvent::construct_impl(realm, HTML::EventNames::complete, event_init));
+            this->dispatch_event(event);
         }));
     }));
 }