Well, I have a class(Timer class) which takes a template paramater, which determines what kind of type the elapsed/absolute time is. My problem is that i can't convert between to types, for example Timer<float> and Timer<double>.
So how can I do this? I have tried doing something like this:
//Typed it in on GDNet, so might have a syntax error or two.
template<class T2>
operator Timer<T2>()
{
Timer Temp;
Temp.mElapsedMS = mElapsedMS;
Temp.mInvMSFrequency = mInvMSFrequency;
Temp.mLastTime = mLastTime;
Temp.mUsingPerformanceCounter = mUsingPerformanceCounter;
return Temp;
}
The problem with this approach is that I can't access Temp's protected members. So I tried something with friends(the C++ ones), but I couldn't get it to work. Does anyone have a way to do this? I don't want to make my members public or make getters and setter for all members.
The full source of my Timer class is here:
//Class: Timer
//Used to get absolute and/or relative(from last update)
//time.
template < typename T = double >
class Timer
{
public:
Timer()
{
//Retrieve the frequency, if performance counters are supported. Also
//set mUsingPerformanceCounter to true if performance counters are supported,
//if not set to false.
INT64 Frequency = 0;
mUsingPerformanceCounter = QueryPerformanceFrequency( (LARGE_INTEGER*)&Frequency );
//If performance counters are supported calculate the inverted frequency for
//milliseconds and get the current time.
if(mUsingPerformanceCounter)
{
mInvMSFrequency = static_cast<T>(1000.0)/static_cast<T>(Frequency);
QueryPerformanceCounter( (LARGE_INTEGER*)&mLastTime );
}
//If performance counters aren't supported get last time.
else
{
mLastTime = timeGetTime();
}
}
~Timer()
{
//Reset all members.
//
//Please note that mUsingPerformanceCounter
//is set to TRUE and mInvFrequency is set to
//0, this means that the return of:
//GetElapsed*() and GetAbsolute*() always will be
//0.
mUsingPerformanceCounter = TRUE;
mInvMSFrequency = 0;
mLastTime = 0;
}
//Function: Update
//Update the time. When retrieving the absolute time
//it ain't the current time, but the absolute time at
//the time of the update.
//Relative is also the time between last update and the
//update before.
void Update()
{
if(mUsingPerformanceCounter)
{
//Insert the current time in CurrentTime.
SINT64 CurrentTime = 0;
QueryPerformanceCounter( (LARGE_INTEGER*)&CurrentTime );
//Calculate the number of elapsed milliseconds since last update.
mElapsedMS = static_cast<T>(CurrentTime - mLastTime)*mInvMSFrequency;
//Set the mLastTime variable to the current time
//because this is now the last time.
mLastTime = CurrentTime;
}
//If QueryPerformance* aren't available.
else
{
//Retrieve current time.
DWORD CurrentTime = timeGetTime();
//Calculate the number of elapsed milliseconds.
mElapsedMS = static_cast<T>(CurrentTime-mLastTime);
//Set the mLastTime variable to the current time
//because this is now the last time.
mLastTime = CurrentTime;
}
}
//Function: GetElapsedMS
//Retrieve the time between the last update
//and the update before that in milliseconds.
T GetElapsedMS() const
{
//Just return the member, was calculated in the Update function.
return mElapsedMS;
}
//Function: GetElapsedSecs
//Retrieve the time between the last update
//and the update before that in seconds.
T GetElapsedSecs() const
{
//Just return the number of milliseconds divided by 1000(multiply by
//0.001 equals divide by 1000).
return mElapsedMS*0.001;
}
//Function: GetAbsoluteTimeMS
//Retrieve the absolute time in milliseconds.
T GetAbsoluteTimeMS() const
{
return static_cast<T>(mLastTime)*mInvMSFrequency;
}
protected:
//Variable: mUsingPerformanceCounter
//Marks if a performance counter(QueryPerformance*) is
//used.
BOOL mUsingPerformanceCounter;
//Variable: mInvMSFrequency
//The inverted frequency(1.0/Frequency), only used with performance counters.
T mInvMSFrequency;
//Variable: mElapsedMS
//The number of elapsed milliseconds between last update
//and the update before.
T mElapsedMS;
//Variable: mLastTime
//The absolute time of last update.
//
//Remarks:
//- Multiply by mInvMSFrequency to convert to milliseconds.
//- SINT64 = signed 64 bit integer.
SINT64 mLastTime;
};
