OpenShot Library | libopenshot-audio 0.2.0
juce_Timer.h
1
2/** @weakgroup juce_events-timers
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
27namespace juce
28{
29
30//==============================================================================
31/**
32 Makes repeated callbacks to a virtual method at a specified time interval.
33
34 A Timer's timerCallback() method will be repeatedly called at a given
35 interval. When you create a Timer object, it will do nothing until the
36 startTimer() method is called, which will cause the message thread to
37 start making callbacks at the specified interval, until stopTimer() is called
38 or the object is deleted.
39
40 The time interval isn't guaranteed to be precise to any more than maybe
41 10-20ms, and the intervals may end up being much longer than requested if the
42 system is busy. Because the callbacks are made by the main message thread,
43 anything that blocks the message queue for a period of time will also prevent
44 any timers from running until it can carry on.
45
46 If you need to have a single callback that is shared by multiple timers with
47 different frequencies, then the MultiTimer class allows you to do that - its
48 structure is very similar to the Timer class, but contains multiple timers
49 internally, each one identified by an ID number.
50
51 @see HighResolutionTimer, MultiTimer
52
53 @tags{Events}
54*/
56{
57protected:
58 //==============================================================================
59 /** Creates a Timer.
60 When created, the timer is stopped, so use startTimer() to get it going.
61 */
62 Timer() noexcept;
63
64 /** Creates a copy of another timer.
65
66 Note that this timer won't be started, even if the one you're copying
67 is running.
68 */
69 Timer (const Timer&) noexcept;
70
71public:
72 //==============================================================================
73 /** Destructor. */
74 virtual ~Timer();
75
76 //==============================================================================
77 /** The user-defined callback routine that actually gets called periodically.
78
79 It's perfectly ok to call startTimer() or stopTimer() from within this
80 callback to change the subsequent intervals.
81 */
82 virtual void timerCallback() = 0;
83
84 //==============================================================================
85 /** Starts the timer and sets the length of interval required.
86
87 If the timer is already started, this will reset it, so the
88 time between calling this method and the next timer callback
89 will not be less than the interval length passed in.
90
91 @param intervalInMilliseconds the interval to use (any value less
92 than 1 will be rounded up to 1)
93 */
94 void startTimer (int intervalInMilliseconds) noexcept;
95
96 /** Starts the timer with an interval specified in Hertz.
97 This is effectively the same as calling startTimer (1000 / timerFrequencyHz).
98 */
99 void startTimerHz (int timerFrequencyHz) noexcept;
100
101 /** Stops the timer.
102
103 No more timer callbacks will be triggered after this method returns.
104
105 Note that if you call this from a background thread while the message-thread
106 is already in the middle of your callback, then this method will cancel any
107 future timer callbacks, but it will return without waiting for the current one
108 to finish. The current callback will continue, possibly still running some of
109 your timer code after this method has returned.
110 */
111 void stopTimer() noexcept;
112
113 //==============================================================================
114 /** Returns true if the timer is currently running. */
115 bool isTimerRunning() const noexcept { return timerPeriodMs > 0; }
116
117 /** Returns the timer's interval.
118 @returns the timer's interval in milliseconds if it's running, or 0 if it's not.
119 */
120 int getTimerInterval() const noexcept { return timerPeriodMs; }
121
122 //==============================================================================
123 /** Invokes a lambda after a given number of milliseconds. */
124 static void JUCE_CALLTYPE callAfterDelay (int milliseconds, std::function<void()> functionToCall);
125
126 //==============================================================================
127 /** For internal use only: invokes any timers that need callbacks.
128 Don't call this unless you really know what you're doing!
129 */
130 static void JUCE_CALLTYPE callPendingTimersSynchronously();
131
132private:
133 class TimerThread;
134 friend class TimerThread;
135 size_t positionInQueue = (size_t) -1;
136 int timerPeriodMs = 0;
137
138 Timer& operator= (const Timer&) = delete;
139};
140
141} // namespace juce
142
143/** @}*/
Holds a resizable array of primitive or copy-by-value objects.
Definition juce_Array.h:60
Makes repeated callbacks to a virtual method at a specified time interval.
Definition juce_Timer.h:56
int getTimerInterval() const noexcept
Returns the timer's interval.
Definition juce_Timer.h:120
virtual void timerCallback()=0
The user-defined callback routine that actually gets called periodically.
#define JUCE_API
This macro is added to all JUCE public class declarations.