Source/modules/webaudio/GainNode.h

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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#ifndef GainNode_h
#define GainNode_h

#include "modules/webaudio/AudioNode.h"
#include "modules/webaudio/AudioParam.h"
#include "wtf/PassRefPtr.h"
#include "wtf/Threading.h"

namespace blink {

class AbstractAudioContext;

// GainNode is an AudioNode with one input and one output which applies a gain (volume) change to the audio signal.
// De-zippering (smoothing) is applied when the gain value is changed dynamically.

class GainHandler final : public AudioHandler {
public:
    static PassRefPtr<GainHandler> create(AudioNode&, float sampleRate, AudioParamHandler& gain);

    // AudioHandler
    void process(size_t framesToProcess) override;

    // Called in the main thread when the number of channels for the input may have changed.
    void checkNumberOfChannelsForInput(AudioNodeInput*) override;

private:
    GainHandler(AudioNode&, float sampleRate, AudioParamHandler& gain);

    float m_lastGain; // for de-zippering
    RefPtr<AudioParamHandler> m_gain;

    AudioFloatArray m_sampleAccurateGainValues;
};

class GainNode final : public AudioNode {
    DEFINE_WRAPPERTYPEINFO();
public:
    static GainNode* create(AbstractAudioContext&, float sampleRate);
    DECLARE_VIRTUAL_TRACE();

    AudioParam* gain() const;

private:
    GainNode(AbstractAudioContext&, float sampleRate);

    Member<AudioParam> m_gain;
};

} // namespace blink

#endif // GainNode_h