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