QwtSystemClock Class Reference

QwtSystemClock provides high resolution clock time functions. More...

#include <qwt_system_clock.h>

List of all members.

Public Member Functions

 QwtSystemClock ()
virtual ~QwtSystemClock ()
bool isNull () const
void start ()
double restart ()
double elapsed () const

Static Public Member Functions

static double precision ()

Detailed Description

QwtSystemClock provides high resolution clock time functions.

Sometimes the resolution offered by QTime ( millisecond ) is not accurate enough for implementing time measurements ( f.e. sampling ). QwtSystemClock offers a subset of the QTime functionality using higher resolution timers ( if possible ).

Precision and time intervals are multiples of milliseconds (ms).

Note:
The implementation uses high-resolution performance counter on Windows, mach_absolute_time() on the Mac or POSIX timers on other systems. If none is available it falls back on QTimer.

Constructor & Destructor Documentation

QwtSystemClock::QwtSystemClock (  ) 

Constructs a null clock object.

QwtSystemClock::~QwtSystemClock (  )  [virtual]

Destructor.


Member Function Documentation

double QwtSystemClock::elapsed (  )  const
Returns:
Number of milliseconds that have elapsed since the last time start() or restart() was called or 0.0 for null clocks.
bool QwtSystemClock::isNull (  )  const
Returns:
true if the clock has never been started.
double QwtSystemClock::precision (  )  [static]
Returns:
Accuracy of the system clock in milliseconds.
double QwtSystemClock::restart (  ) 

The start time to the current time and return the time, that is elapsed since the previous start time.

void QwtSystemClock::start (  ) 

Sets the start time to the current time.

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