GoldenCheetah/qwt/examples/oscilloscope/samplingthread.cpp

#include "samplingthread.h"
#include "signaldata.h"
#include <qwt_math.h>
#include <math.h>

#if QT_VERSION < 0x040600
#define qFastSin(x) ::sin(x)
#endif

SamplingThread::SamplingThread(QObject *parent):
    QwtSamplingThread(parent),
    d_frequency(5.0),
    d_amplitude(20.0)
{
}

void SamplingThread::setFrequency(double frequency)
{
    d_frequency = frequency;
}

double SamplingThread::frequency() const
{
    return d_frequency;
}

void SamplingThread::setAmplitude(double amplitude)
{
    d_amplitude = amplitude;
}

double SamplingThread::amplitude() const
{
    return d_amplitude;
}

void SamplingThread::sample(double elapsed)
{
    if ( d_frequency > 0.0 )
    {
        const QPointF s(elapsed, value(elapsed));
        SignalData::instance().append(s);
    }
}

double SamplingThread::value(double timeStamp) const
{
    const double period = 1.0 / d_frequency;

    const double x = ::fmod(timeStamp, period);
    const double v = d_amplitude * qFastSin(x / period * 2 * M_PI);

    return v;
}