#include <qwt_plot.h>#include "cpustat.h"#define HISTORY 60 // secondsclass QwtPlotCurve;class CpuPlot : public QwtPlot {    Q_OBJECTpublic:    enum CpuData    {        User,        System,        Total,        Idle,        NCpuData    };    CpuPlot(QWidget * = 0);    const QwtPlotCurve *cpuCurve(int id) const        { return data[id].curve; }protected:    void timerEvent(QTimerEvent *e);private slots:    void showCurve(QwtPlotItem *, bool on);private:    struct    {        QwtPlotCurve *curve;        double data[HISTORY];    } data[NCpuData];    double timeData[HISTORY];    int dataCount;    CpuStat cpuStat;};