OpenShot Library | libopenshot-audio  0.2.0
juce_HighResolutionTimer.h
1 
2 /** @weakgroup juce_core-threads
3  * @{
4  */
5 /*
6  ==============================================================================
7 
8  This file is part of the JUCE library.
9  Copyright (c) 2017 - ROLI Ltd.
10 
11  JUCE is an open source library subject to commercial or open-source
12  licensing.
13 
14  The code included in this file is provided under the terms of the ISC license
15  http://www.isc.org/downloads/software-support-policy/isc-license. Permission
16  To use, copy, modify, and/or distribute this software for any purpose with or
17  without fee is hereby granted provided that the above copyright notice and
18  this permission notice appear in all copies.
19 
20  JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
21  EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
22  DISCLAIMED.
23 
24  ==============================================================================
25 */
26 
27 namespace juce
28 {
29 
30 /**
31  A high-resolution periodic timer.
32 
33  This provides accurately-timed regular callbacks. Unlike the normal Timer
34  class, this one uses a dedicated thread, not the message thread, so is
35  far more stable and precise.
36 
37  You should only use this class in situations where you really need accuracy,
38  because unlike the normal Timer class, which is very lightweight and cheap
39  to start/stop, the HighResolutionTimer will use far more resources, and
40  starting/stopping it may involve launching and killing threads.
41 
42  @see Timer
43 
44  @tags{Core}
45 */
47 {
48 protected:
49  /** Creates a HighResolutionTimer.
50  When created, the timer is stopped, so use startTimer() to get it going.
51  */
53 
54 public:
55  /** Destructor. */
56  virtual ~HighResolutionTimer();
57 
58  //==============================================================================
59  /** The user-defined callback routine that actually gets called periodically.
60 
61  This will be called on a dedicated timer thread, so make sure your
62  implementation is thread-safe!
63 
64  It's perfectly ok to call startTimer() or stopTimer() from within this
65  callback to change the subsequent intervals.
66  */
67  virtual void hiResTimerCallback() = 0;
68 
69  //==============================================================================
70  /** Starts the timer and sets the length of interval required.
71 
72  If the timer is already started, this will reset its counter, so the
73  time between calling this method and the next timer callback will not be
74  less than the interval length passed in.
75 
76  @param intervalInMilliseconds the interval to use (any values less than 1 will be
77  rounded up to 1)
78  */
79  void startTimer (int intervalInMilliseconds);
80 
81  /** Stops the timer.
82 
83  This method may block while it waits for pending callbacks to complete. Once it
84  returns, no more callbacks will be made. If it is called from the timer's own thread,
85  it will cancel the timer after the current callback returns.
86  */
87  void stopTimer();
88 
89  /** Checks if the timer has been started.
90  @returns true if the timer is running.
91  */
92  bool isTimerRunning() const noexcept;
93 
94  /** Returns the timer's interval.
95  @returns the timer's interval in milliseconds if it's running, or 0 if it's not.
96  */
97  int getTimerInterval() const noexcept;
98 
99 private:
100  struct Pimpl;
101  std::unique_ptr<Pimpl> pimpl;
102 
103  JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (HighResolutionTimer)
104 };
105 
106 } // namespace juce
107 
108 /** @}*/
#define JUCE_API
This macro is added to all JUCE public class declarations.
A high-resolution periodic timer.