vislu/qt-test/Timer.h

#pragma once

#include "common.h"
#include <windows.h>
#include <time.h>

// Timer class using the high-resolution performance counter
class Timer
{
public:

        Timer() : m_dStart(0.0), m_dCurrent(0.0), m_bRunning(false)
        {
                if (s_dSecondsPerTick <= 0.0)
                {
                        LARGE_INTEGER frequency;
                        
                        if (QueryPerformanceFrequency(&frequency))
                                s_dSecondsPerTick = 1.0 / double(frequency.QuadPart);
                        else
                                s_dSecondsPerTick = 1.0 / double(CLOCKS_PER_SEC);
                }

                start();
        };

        ~Timer()
        {
        };

        void start()
        {
                m_bRunning = true;
                m_dStart = m_dCurrent = GetCurrentTime();
        };

        void stop()
        {
                m_dCurrent = GetCurrentTime();
                m_bRunning = false;
        };

        operator double() const
        {
                return GetCurrentTime() - GetStartTime();
        };

        operator float() const
        {
                return float(GetCurrentTime() - GetStartTime());
        };

        const bool IsRunning() const
        {
                return m_bRunning;
        };

private:

        const double GetCurrentClock() const
        {
                LARGE_INTEGER now;

                if (QueryPerformanceCounter(&now))
                        return double(now.QuadPart);
                
                return double(clock());
        };

        const double GetStartTime() const
        {
                return m_dStart;
        };

        const double GetCurrentTime() const
        {
                if (m_bRunning)
                        return GetCurrentClock() * s_dSecondsPerTick;
                
                return m_dCurrent;
        };

private:

        double m_dStart;
        double m_dCurrent;
        bool m_bRunning;
        static double s_dSecondsPerTick;
};