root/OscillatorNode.h

INCLUDED FROM

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#ifndef OscillatorNode_h
#define OscillatorNode_h

#include "core/platform/audio/AudioBus.h"
#include "modules/webaudio/AudioParam.h"
#include "modules/webaudio/AudioScheduledSourceNode.h"
#include "wtf/OwnArrayPtr.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/Threading.h"

namespace WebCore {

class AudioContext;
class PeriodicWave;

// OscillatorNode is an audio generator of periodic waveforms.

class OscillatorNode : public AudioScheduledSourceNode {
public:
    // The waveform type.
    // These must be defined as in the .idl file.
    enum {
        SINE = 0,
        SQUARE = 1,
        SAWTOOTH = 2,
        TRIANGLE = 3,
        CUSTOM = 4
    };

    static PassRefPtr<OscillatorNode> create(AudioContext*, float sampleRate);

    virtual ~OscillatorNode();

    // AudioNode
    virtual void process(size_t framesToProcess);
    virtual void reset();

    String type() const;

    bool setType(unsigned); // Returns true on success.
    void setType(const String&);

    AudioParam* frequency() { return m_frequency.get(); }
    AudioParam* detune() { return m_detune.get(); }

    void setPeriodicWave(PeriodicWave*);

private:
    OscillatorNode(AudioContext*, float sampleRate);

    // Returns true if there are sample-accurate timeline parameter changes.
    bool calculateSampleAccuratePhaseIncrements(size_t framesToProcess);

    virtual bool propagatesSilence() const OVERRIDE;

    // One of the waveform types defined in the enum.
    unsigned short m_type;

    // Frequency value in Hertz.
    RefPtr<AudioParam> m_frequency;

    // Detune value (deviating from the frequency) in Cents.
    RefPtr<AudioParam> m_detune;

    bool m_firstRender;

    // m_virtualReadIndex is a sample-frame index into our buffer representing the current playback position.
    // Since it's floating-point, it has sub-sample accuracy.
    double m_virtualReadIndex;

    // This synchronizes process().
    mutable Mutex m_processLock;

    // Stores sample-accurate values calculated according to frequency and detune.
    AudioFloatArray m_phaseIncrements;
    AudioFloatArray m_detuneValues;

    RefPtr<PeriodicWave> m_periodicWave;

    // Cache the wave tables for different waveform types, except CUSTOM.
    static PeriodicWave* s_periodicWaveSine;
    static PeriodicWave* s_periodicWaveSquare;
    static PeriodicWave* s_periodicWaveSawtooth;
    static PeriodicWave* s_periodicWaveTriangle;
};

} // namespace WebCore

#endif // OscillatorNode_h