fpsmeter.cpp

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/*
    Copyright (C) 2020 by Pawel Soja <kernel32.pl@gmail.com>
    FPS Meter
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
 
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
*/
#include "fpsmeter.h"
 
namespace INDI
{
 
FPSMeter::FPSMeter(double timeWindow)
    : mTimeWindow(timeWindow)
{
    reset();
}
 
bool FPSMeter::newFrame()
{
    mFrameTime2 = mFrameTime1;
    mFrameTime1 = std::chrono::steady_clock::now();
    
    ++mTotalFrames;
    ++mFramesPerElapsedTime;
 
    double dt = deltaTime();
 
    mElapsedTime += dt;
    mTotalTime   += dt;
 
    if (mElapsedTime >= mTimeWindow)
    {            
        mFramesPerSecond = mFramesPerElapsedTime / mElapsedTime * 1000;
        mElapsedTime = 0;
        mFramesPerElapsedTime = 0;
        return true;
    }
 
    return false;
}
 
void FPSMeter::setTimeWindow(double timeWindow)
{
    mTimeWindow = timeWindow;
}
 
double FPSMeter::framesPerSecond() const
{
    return mFramesPerSecond;
}
 
double FPSMeter::deltaTime() const
{
    return std::chrono::duration<double>(mFrameTime1 - mFrameTime2).count() * 1000;
}
 
uint64_t FPSMeter::totalFrames() const
{
    return mTotalFrames;
}
 
double FPSMeter::totalTime() const
{
    return mTotalTime;
}
 
void FPSMeter::reset()
{
    mFramesPerElapsedTime = 0;
    mElapsedTime = 0;
    mFrameTime1 = std::chrono::steady_clock::now();
    mFrameTime2 = mFrameTime1;
    mFramesPerSecond = 0;
    mTotalFrames = 0;
    mTotalTime = 0;
}
 
}