Timer Impl

Timer.h

#include <chrono>

namespace cinder {
	
// nanoseconds Alias
using nanoseconds = std::chrono::nanoseconds;

/** \brief A high-resolution timer class **/
class Timer {
	using clock = std::chrono::high_resolution_clock;
  public:
	//! Constructs a default timer which is initialized as stopped
	Timer();
	//! Constructs a default timer which is initialized as running unless \a startOnConstruction is false
	Timer( bool startOnConstruction );
	
	//! Begins timing. Optional \a offsetSeconds parameter allows a relative offset
	void	start( nanoseconds offset = nanoseconds( 0 ) );
	//! Resumes timing without resetting the timer.
	void	resume();
	//! Ends timing
	void	stop();
	
	//! Returns the elapsed seconds if the timer is running, or the total time between calls to start() and stop() if it is stopped.
	double	getSeconds() const;
	//! Returns nanosecond type from chrono of the elapsed ticks from the system clock.
	nanoseconds getElapsedTicks() const;

	//! Returns whether the timer is currently running
	bool	isStopped() const { return !mIsRunning; }
	
  private:
	
	clock::time_point	mStartTime;
	clock::duration		mCurrentDuration;
	bool				mIsRunning;
};

inline Timer::Timer()
	: mIsRunning( false ), mCurrentDuration( 0 )
{
}
	
inline Timer::Timer( bool startOnConstruction )
	: mIsRunning( false ), mCurrentDuration( 0 )
{
	if( startOnConstruction )
		start();
}

inline void Timer::start( nanoseconds offset )
{
	mStartTime = clock::now();
	mCurrentDuration = offset;
	mIsRunning = true;
}
	
inline void Timer::resume()
{
	if( mIsRunning )
		return;
	mStartTime = clock::now();
	mIsRunning = true;
}
	
inline void Timer::stop()
{
	if( ! mIsRunning )
		return;
	mIsRunning = false;
	mCurrentDuration += (clock::now() - mStartTime);
}
	
inline nanoseconds Timer::getElapsedTicks() const
{
	if( ! mIsRunning )
		return mCurrentDuration;
	else
		return mCurrentDuration + (clock::now() - mStartTime);
}
	
inline double Timer::getSeconds() const
{
	return getElapsedTicks().count() * 0.000000001;
}
	
} // namespace cinder