root/Source/modules/webaudio/AudioParam.h

INCLUDED FROM

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#ifndef AudioParam_h
#define AudioParam_h

#include "bindings/v8/ScriptWrappable.h"
#include "modules/webaudio/AudioContext.h"
#include "modules/webaudio/AudioParamTimeline.h"
#include "modules/webaudio/AudioSummingJunction.h"
#include <sys/types.h>
#include "wtf/Float32Array.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

class AudioNodeOutput;

class AudioParam FINAL : public RefCounted<AudioParam>, public ScriptWrappable, public AudioSummingJunction {
public:
    static const double DefaultSmoothingConstant;
    static const double SnapThreshold;

    static PassRefPtr<AudioParam> create(AudioContext* context, const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
    {
        return adoptRef(new AudioParam(context, name, defaultValue, minValue, maxValue, units));
    }

    // AudioSummingJunction
    virtual bool canUpdateState() OVERRIDE { return true; }
    virtual void didUpdate() OVERRIDE { }

    // Intrinsic value.
    float value();
    void setValue(float);

    // Final value for k-rate parameters, otherwise use calculateSampleAccurateValues() for a-rate.
    // Must be called in the audio thread.
    float finalValue();

    String name() const { return m_name; }

    float minValue() const { return static_cast<float>(m_minValue); }
    float maxValue() const { return static_cast<float>(m_maxValue); }
    float defaultValue() const { return static_cast<float>(m_defaultValue); }
    unsigned units() const { return m_units; }

    // Value smoothing:

    // When a new value is set with setValue(), in our internal use of the parameter we don't immediately jump to it.
    // Instead we smoothly approach this value to avoid glitching.
    float smoothedValue();

    // Smoothly exponentially approaches to (de-zippers) the desired value.
    // Returns true if smoothed value has already snapped exactly to value.
    bool smooth();

    void resetSmoothedValue() { m_smoothedValue = m_value; }

    // Parameter automation.
    void setValueAtTime(float value, double time) { m_timeline.setValueAtTime(value, time); }
    void linearRampToValueAtTime(float value, double time) { m_timeline.linearRampToValueAtTime(value, time); }
    void exponentialRampToValueAtTime(float value, double time, ExceptionState& es) { m_timeline.exponentialRampToValueAtTime(value, time, es); }
    void setTargetAtTime(float target, double time, double timeConstant) { m_timeline.setTargetAtTime(target, time, timeConstant); }
    void setValueCurveAtTime(Float32Array* curve, double time, double duration) { m_timeline.setValueCurveAtTime(curve, time, duration); }
    void cancelScheduledValues(double startTime) { m_timeline.cancelScheduledValues(startTime); }

    bool hasSampleAccurateValues() { return m_timeline.hasValues() || numberOfRenderingConnections(); }

    // Calculates numberOfValues parameter values starting at the context's current time.
    // Must be called in the context's render thread.
    void calculateSampleAccurateValues(float* values, unsigned numberOfValues);

    // Connect an audio-rate signal to control this parameter.
    void connect(AudioNodeOutput*);
    void disconnect(AudioNodeOutput*);

protected:
    AudioParam(AudioContext* context, const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
        : AudioSummingJunction(context)
        , m_name(name)
        , m_value(defaultValue)
        , m_defaultValue(defaultValue)
        , m_minValue(minValue)
        , m_maxValue(maxValue)
        , m_units(units)
        , m_smoothedValue(defaultValue)
    {
        ScriptWrappable::init(this);
    }

private:
    // sampleAccurate corresponds to a-rate (audio rate) vs. k-rate in the Web Audio specification.
    void calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate);
    void calculateTimelineValues(float* values, unsigned numberOfValues);

    String m_name;
    double m_value;
    double m_defaultValue;
    double m_minValue;
    double m_maxValue;
    unsigned m_units;

    // Smoothing (de-zippering)
    double m_smoothedValue;

    AudioParamTimeline m_timeline;
};

} // namespace WebCore

#endif // AudioParam_h