class CFpsSta{public:    time_t m_start_time;    bool flag;    float m_count;    float m_last_fps;    CFpsSta();    void checkFps();};

void CFpsSta::checkFps(){    time_t current_time=time(NULL);    double diff=difftime(current_time,m_start_time);        if (diff>=5 && !flag)    {        m_last_fps=m_count/diff;        cout<<m_last_fps<<endl;        flag=true;        m_start_time=current_time;        m_count=0;    }    if ( flag)    {        flag=false;    }    }

每5秒计算一次平均帧率，并清空数值，重新计数；下一次调用时，重设flag；  其中m_count在绘制函数后++。

class CFpsSta2{public:queue<time_t> counts;CFpsSta2();void checkFps();};

void CFpsSta2::checkFps(){    time_t current_time=time(NULL);    counts.push(current_time);    double diff=current_time-counts.front();    //cout<<diff<<endl;    if(diff>=1)    {        cout<<counts.size()/diff<<endl;        while(!counts.empty())            counts.pop();        }}