LibWeb: Add ConstantSourceNode interface

Author: https://github.com/tcl3
Commit: 1b160044c4
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3102
Reviewed-by: https://github.com/shannonbooth

Libraries/LibWeb/WebAudio/ConstantSourceNode.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2025, Tim Ledbetter <tim.ledbetter@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/WebAudio/AudioScheduledSourceNode.h>
+
+namespace Web::WebAudio {
+
+// https://webaudio.github.io/web-audio-api/#ChannelMergerOptions
+struct ConstantSourceOptions : AudioNodeOptions {
+    float offset { 1.0f };
+};
+
+// https://webaudio.github.io/web-audio-api/#ChannelMergerNode
+class ConstantSourceNode final : public AudioScheduledSourceNode {
+    WEB_PLATFORM_OBJECT(ConstantSourceNode, AudioScheduledSourceNode);
+    GC_DECLARE_ALLOCATOR(ConstantSourceNode);
+
+public:
+    virtual ~ConstantSourceNode() override;
+
+    static WebIDL::ExceptionOr<GC::Ref<ConstantSourceNode>> create(JS::Realm&, GC::Ref<BaseAudioContext>, ConstantSourceOptions const& = {});
+    static WebIDL::ExceptionOr<GC::Ref<ConstantSourceNode>> construct_impl(JS::Realm&, GC::Ref<BaseAudioContext>, ConstantSourceOptions const& = {});
+
+    virtual WebIDL::UnsignedLong number_of_inputs() override { return 0; }
+    virtual WebIDL::UnsignedLong number_of_outputs() override { return 1; }
+
+    GC::Ref<AudioParam const> offset() const { return m_offset; }
+
+private:
+    ConstantSourceNode(JS::Realm&, GC::Ref<BaseAudioContext>, ConstantSourceOptions const&);
+
+    virtual void initialize(JS::Realm&) override;
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    // https://webaudio.github.io/web-audio-api/#dom-constantsourcenode-offset
+    GC::Ref<AudioParam> m_offset;
+};
+
+}