#include <qwt_sampling_thread.h> class SamplingThread: public QwtSamplingThread { Q_OBJECT public: SamplingThread(QObject *parent = NULL); double frequency() const; double amplitude() const; public Q_SLOTS: void setAmplitude(double); void setFrequency(double); protected: virtual void sample(double elapsed); private: virtual double value(double timeStamp) const; double d_frequency; double d_amplitude; };