include/canvas/elapsedtime.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_CANVAS_ELAPSEDTIME_HXX
  21 #define INCLUDED_CANVAS_ELAPSEDTIME_HXX
  22
  23 #include <sal/types.h>
  24
  25 #include "boost/shared_ptr.hpp"
  26 #include <canvas/canvastoolsdllapi.h>
  27
  28 namespace canvas
  29 {
  30     namespace tools
  31     {
  32         /** Calculate elapsed time.
  33
  34             This class provides several time-measurement and
  35             -management functions. In its simplest use-case, it
  36             measures the time from its creation.
  37          */
  38         class CANVASTOOLS_DLLPUBLIC ElapsedTime
  39         {
  40         public:
  41             /** Create a new ElapsedTime object
  42
  43                 The moment of construction starts the time
  44                 measurement. That means, a subsequent getElapsedTime()
  45                 call will return the time difference between object
  46                 creation and getElapsedTime() call.
  47              */
  48             ElapsedTime();
  49
  50             /** Creates a new ElapsedTime object based on another
  51                 timer.
  52
  53                 The moment of construction starts the time
  54                 measurement. That means, a subsequent getElapsedTime()
  55                 call will return the time difference between object
  56                 creation and getElapsedTime() call. All time values
  57                 are not taken from the system's time base, but from
  58                 the provided timer.
  59              */
  60             ElapsedTime( ::boost::shared_ptr<ElapsedTime> const & pTimeBase );
  61
  62             /** Reset the time
  63
  64                 The instance of the reset() call starts the time
  65                 measurement from scratch. That means, a subsequent
  66                 getElapsedTime() call will return the time difference
  67                 between reset() and getElapsedTime() call.
  68              */
  69             void reset();
  70
  71             /** Query the elapsed time
  72
  73                 This method returns the elapsed time in seconds
  74                 between either the construction of this object, or the
  75                 last reset() call, if any (but see the time modulation
  76                 methods below, for means to modify the otherwise
  77                 continuous flow of time).
  78
  79                 @return the elapsed time in seconds.
  80              */
  81             double getElapsedTime() const;
  82
  83             /** Pauses the running timer.
  84
  85                 This method stops the time, as returned by this
  86                 object, until continueTimer() is called. During this
  87                 period, getElapsedTime() will always return the same
  88                 time value (i.e. the instant when pauseTimer() was
  89                 called).
  90              */
  91             void pauseTimer();
  92
  93             /** Continues the paused timer.
  94
  95                 This method re-enables the time flow, that is, time
  96                 starts running again for clients calling
  97                 getElapsedTime(). The (subtle) difference to the
  98                 holdTimer/releaseTimer() methods below is, that there
  99                 is no perceived time 'jump' between the pauseTimer()
 100                 call and the continueTimer() call, i.e. the time
 101                 starts over with the same value it has stopped on
 102                 pauseTimer().
 103              */
 104             void continueTimer();
 105
 106             /** Adjusts the timer, hold and pause times.
 107
 108                 This method modifies the time as returned by this
 109                 object by the specified amount. This affects the time
 110                 as returned by getElapsedTime(), regardless of the
 111                 mode (e.g. paused, or on hold).
 112
 113                 @param fOffset
 114                 This value will be added to the current time, i.e. the
 115                 next call to getElapsedTime() (when performed
 116                 immediately) will be adjusted by fOffset.
 117
 118                 @param bLimitToLastQueriedTime
 119                 Limits the given offset to the time that has been
 120                 taken via getElapsedTime()
 121             */
 122             void adjustTimer( double fOffset,
 123                               bool bLimitToLastQueriedTime = true );
 124
 125             /** Holds the current time.
 126
 127                 This call makes the timer hold the current time
 128                 (e.g. getElapsedTime() will return the time when
 129                 holdTimer() was called), while the underlying time is
 130                 running on. When releaseTimer() is called, the time
 131                 will 'jump' to the then-current, underlying time. This
 132                 is equivalent to pressing the "interim time" button on
 133                 a stop watch, which shows this stopped time, while the
 134                 clock keeps running internally.
 135             */
 136             void holdTimer();
 137
 138             /** Releases a held timer.
 139
 140                 After this call, the timer again returns the running
 141                 time on getElapsedTime().
 142              */
 143             void releaseTimer();
 144
 145         private:
 146             static double getSystemTime();
 147             double getCurrentTime() const;
 148             double getElapsedTimeImpl() const; // does not set m_fLastQueriedTime
 149
 150             const ::boost::shared_ptr<ElapsedTime>  m_pTimeBase;
 151
 152             /// To validate adjustTimer() calls with bLimitToLastQueriedTime=true
 153             mutable double                          m_fLastQueriedTime;
 154
 155             /// Start time, from which the difference to the time base is returned
 156             double                                  m_fStartTime;
 157
 158             /// Instant, when last pause or hold started, relative to m_fStartTime
 159             double                                  m_fFrozenTime;
 160
 161             /// True, when in pause mode
 162             bool                                    m_bInPauseMode;
 163
 164             /// True, when in hold mode
 165             bool                                    m_bInHoldMode;
 166         };
 167
 168     }
 169 }
 170
 171 #endif /* INCLUDED_CANVAS_ELAPSEDTIME_HXX */
 172
 173 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */