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JUCE/modules/juce_events/timers/juce_Timer.h

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/*
==============================================================================
This file is part of the JUCE library - "Jules' Utility Class Extensions"
Copyright 2004-11 by Raw Material Software Ltd.
------------------------------------------------------------------------------
JUCE can be redistributed and/or modified under the terms of the GNU General
Public License (Version 2), as published by the Free Software Foundation.
A copy of the license is included in the JUCE distribution, or can be found
online at www.gnu.org/licenses.
JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
------------------------------------------------------------------------------
To release a closed-source product which uses JUCE, commercial licenses are
available: visit www.rawmaterialsoftware.com/juce for more information.
==============================================================================
*/
#ifndef __JUCE_TIMER_JUCEHEADER__
#define __JUCE_TIMER_JUCEHEADER__
class InternalTimerThread;
//==============================================================================
/**
Makes repeated callbacks to a virtual method at a specified time interval.
A Timer's timerCallback() method will be repeatedly called at a given
interval. When you create a Timer object, it will do nothing until the
startTimer() method is called, which will cause the message thread to
start making callbacks at the specified interval, until stopTimer() is called
or the object is deleted.
The time interval isn't guaranteed to be precise to any more than maybe
10-20ms, and the intervals may end up being much longer than requested if the
system is busy. Because the callbacks are made by the main message thread,
anything that blocks the message queue for a period of time will also prevent
any timers from running until it can carry on.
If you need to have a single callback that is shared by multiple timers with
different frequencies, then the MultiTimer class allows you to do that - its
structure is very similar to the Timer class, but contains multiple timers
internally, each one identified by an ID number.
@see MultiTimer
*/
class JUCE_API Timer
{
protected:
//==============================================================================
/** Creates a Timer.
When created, the timer is stopped, so use startTimer() to get it going.
*/
Timer() noexcept;
/** Creates a copy of another timer.
Note that this timer won't be started, even if the one you're copying
is running.
*/
Timer (const Timer& other) noexcept;
public:
//==============================================================================
/** Destructor. */
virtual ~Timer();
//==============================================================================
/** The user-defined callback routine that actually gets called periodically.
It's perfectly ok to call startTimer() or stopTimer() from within this
callback to change the subsequent intervals.
*/
virtual void timerCallback() = 0;
//==============================================================================
/** Starts the timer and sets the length of interval required.
If the timer is already started, this will reset it, so the
time between calling this method and the next timer callback
will not be less than the interval length passed in.
@param intervalInMilliseconds the interval to use (any values less than 1 will be
rounded up to 1)
*/
void startTimer (int intervalInMilliseconds) noexcept;
/** Stops the timer.
No more callbacks will be made after this method returns.
If this is called from a different thread, any callbacks that may
be currently executing may be allowed to finish before the method
returns.
*/
void stopTimer() noexcept;
//==============================================================================
/** Checks if the timer has been started.
@returns true if the timer is running.
*/
bool isTimerRunning() const noexcept { return periodMs > 0; }
/** Returns the timer's interval.
@returns the timer's interval in milliseconds if it's running, or 0 if it's not.
*/
int getTimerInterval() const noexcept { return periodMs; }
//==============================================================================
private:
friend class InternalTimerThread;
int countdownMs, periodMs;
Timer* previous;
Timer* next;
Timer& operator= (const Timer&);
};
#endif // __JUCE_TIMER_JUCEHEADER__