QwtSystemClock Class Reference

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

#include <qwt_system_clock.h>

List of all members.

Public Member Functions

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

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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