Implement ConstantSourceNode

third_party/WebKit/Source/modules/webaudio/ConstantSourceNode.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ConstantSourceNode_h
+#define ConstantSourceNode_h
+
+#include "modules/webaudio/AudioParam.h"
+#include "modules/webaudio/AudioScheduledSourceNode.h"
+#include "platform/audio/AudioBus.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefPtr.h"
+#include "wtf/Threading.h"
+
+namespace blink {
+
+class BaseAudioContext;
+class ConstantSourceOptions;
+class ExceptionState;
+
+// ConstantSourceNode is an audio generator for a constant source
+
+class ConstantSourceHandler final : public AudioScheduledSourceHandler {
+public:
+    static PassRefPtr<ConstantSourceHandler> create(
+        AudioNode&, float sampleRate, AudioParamHandler& offset);
+    ~ConstantSourceHandler() override;
+
+    // AudioHandler
+    void process(size_t framesToProcess) override;
+private:
+    ConstantSourceHandler(AudioNode&, float sampleRate, AudioParamHandler& offset);
+
+    // If we are no longer playing, propogate silence ahead to downstream nodes.
+    bool propagatesSilence() const override;
+
+    RefPtr<AudioParamHandler> m_offset;
+    AudioFloatArray m_sampleAccurateValues;
+};
+
+class ConstantSourceNode final : public AudioScheduledSourceNode {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static ConstantSourceNode* create(BaseAudioContext&, ExceptionState&);
+    static ConstantSourceNode* create(BaseAudioContext*, const ConstantSourceOptions&, ExceptionState&);
+    DECLARE_VIRTUAL_TRACE();
+
+    AudioParam* offset();
+
+private:
+    ConstantSourceNode(BaseAudioContext&);
+    ConstantSourceHandler& constantSourceHandler() const;
+
+    Member<AudioParam> m_offset;
+};
+
+} // namespace blink
+
+#endif // ConstantSourceNode_h