src/libpcp_qwt/src/qwt_system_clock.h

   1 /* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
   2  * Qwt Widget Library
   3  * Copyright (C) 1997   Josef Wilgen
   4  * Copyright (C) 2002   Uwe Rathmann
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the Qwt License, Version 1.0
   8  *****************************************************************************/
   9
  10 #ifndef QWT_SYSTEM_CLOCK_H
  11 #define QWT_SYSTEM_CLOCK_H
  12
  13 #include "qwt_global.h"
  14
  15 /*!
  16   \brief QwtSystemClock provides high resolution clock time functions.
  17
  18   Sometimes the resolution offered by QTime ( millisecond ) is not accurate
  19   enough for implementing time measurements ( f.e. sampling ).
  20   QwtSystemClock offers a subset of the QTime functionality using higher
  21   resolution timers ( if possible ).
  22
  23   Precision and time intervals are multiples of milliseconds (ms).
  24
  25   \note The implementation uses high-resolution performance counter on Windows,
  26         mach_absolute_time() on the Mac or POSIX timers on other systems.
  27         If none is available it falls back on QTimer.
  28 */
  29
  30 class QWT_EXPORT QwtSystemClock
  31 {
  32 public:
  33     QwtSystemClock();
  34     virtual ~QwtSystemClock();
  35
  36     bool isNull() const;
  37
  38     void start();
  39     double restart();
  40     double elapsed() const;
  41
  42 private:
  43     class PrivateData;
  44     PrivateData *d_data;
  45 };
  46
  47 #endif