QwtSystemClock - QwtSystemClock provides high resolution clock time functions.

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Version 6.1.4                                    Wed Jan 2 2019                                QwtSystemClock(3)

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).

       ( QwtSystemClock is obsolete since Qt 4.8 as QElapsedTimer offers the same precision )

       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.

doubleQwtSystemClock::elapsed()constReturns:
           Number of milliseconds that have elapsed since the last time start() or restart() was called or 0.0
           for null clocks.

   boolQwtSystemClock::isNull()constReturns:
           true if the clock has never been started.

   doubleQwtSystemClock::restart()
       Set the start time to the current time

       Returns:
           Time, that is elapsed since the previous start time.

   voidQwtSystemClock::start()
       Sets the start time to the current time.

       QwtSystemClock - QwtSystemClock provides high resolution clock time functions.

       #include <qwt_system_clock.h>

   PublicMemberFunctionsQwtSystemClock ()
           Constructs a null clock object.
       virtual ~QwtSystemClock ()
           Destructor.
       bool isNull () const
       void start ()
       double restart ()
       double elapsed () const