MessageManager Class Reference

This class is in charge of the application's event-dispatch loop. More...

#include <juce_MessageManager.h>

Classes
class	Lock
	A lock you can use to lock the message manager. More...
class	MessageBase
	Internal class used as the base class for all message objects. More...

Public Member Functions
void	runDispatchLoop ()
	Runs the event dispatch loop until a stop message is posted.
void	stopDispatchLoop ()
	Sends a signal that the dispatch loop should terminate.
bool	hasStopMessageBeenSent () const noexcept
	Returns true if the stopDispatchLoop() method has been called.
bool	runDispatchLoopUntil (int millisecondsToRunFor)
	Synchronously dispatches messages until a given time has elapsed.
void *	callFunctionOnMessageThread (MessageCallbackFunction *callback, void *userData)
	Calls a function using the message-thread.
bool	isThisTheMessageThread () const noexcept
	Returns true if the caller-thread is the message thread.
void	setCurrentThreadAsMessageThread ()
	Called to tell the manager that the current thread is the one that's running the dispatch loop.
Thread::ThreadID	getCurrentMessageThread () const noexcept
	Returns the ID of the current message thread, as set by setCurrentThreadAsMessageThread().
bool	currentThreadHasLockedMessageManager () const noexcept
	Returns true if the caller thread has currently got the message manager locked.
void	registerBroadcastListener (ActionListener *listener)
	Registers a listener to get told about broadcast messages.
void	deregisterBroadcastListener (ActionListener *listener)
	Deregisters a broadcast listener.

Static Public Member Functions
static MessageManager *	getInstance ()
	Returns the global instance of the MessageManager.
static MessageManager *	getInstanceWithoutCreating () noexcept
	Returns the global instance of the MessageManager, or nullptr if it doesn't exist.
static void	deleteInstance ()
	Deletes the global MessageManager instance.
static bool	callAsync (std::function< void()> functionToCall)
	Asynchronously invokes a function or C++11 lambda on the message thread.
static bool	existsAndIsLockedByCurrentThread () noexcept
	Returns true if there's an instance of the MessageManager, and if the current thread has the lock on it.
static bool	existsAndIsCurrentThread () noexcept
	Returns true if there's an instance of the MessageManager, and if the current thread is running it.
static void	broadcastMessage (const String &messageText)
	Sends a message to all other JUCE applications that are running.

Detailed Description

This class is in charge of the application's event-dispatch loop.

See also

Message, CallbackMessage, MessageManagerLock, JUCEApplication, JUCEApplicationBase

Member Function Documentation

getInstance()

static MessageManager * MessageManager::getInstance ( )

static

Returns the global instance of the MessageManager.

getInstanceWithoutCreating()

static MessageManager * MessageManager::getInstanceWithoutCreating ( )

staticnoexcept

Returns the global instance of the MessageManager, or nullptr if it doesn't exist.

deleteInstance()

static void MessageManager::deleteInstance ( )

static

Deletes the global MessageManager instance.

Does nothing if no instance had been created.

runDispatchLoop()

void MessageManager::runDispatchLoop

(

)

Runs the event dispatch loop until a stop message is posted.

This method is only intended to be run by the application's startup routine, as it blocks, and will only return after the stopDispatchLoop() method has been used.

See also

stopDispatchLoop

stopDispatchLoop()

void MessageManager::stopDispatchLoop

(

)

Sends a signal that the dispatch loop should terminate.

After this is called, the runDispatchLoop() or runDispatchLoopUntil() methods will be interrupted and will return.

See also

runDispatchLoop

hasStopMessageBeenSent()

bool MessageManager::hasStopMessageBeenSent ( ) const

noexcept

Returns true if the stopDispatchLoop() method has been called.

runDispatchLoopUntil()

bool MessageManager::runDispatchLoopUntil

(

int

millisecondsToRunFor

)

Synchronously dispatches messages until a given time has elapsed.

Returns false if a quit message has been posted by a call to stopDispatchLoop(), otherwise returns true.

callAsync()

static bool MessageManager::callAsync ( std::function< void()>  functionToCall )

static

Asynchronously invokes a function or C++11 lambda on the message thread.

Returns

true if the message was successfully posted to the message queue, or false otherwise.

callFunctionOnMessageThread()

void * MessageManager::callFunctionOnMessageThread	(	MessageCallbackFunction *	callback,
		void *	userData
	)

Calls a function using the message-thread.

This can be used by any thread to cause this function to be called-back by the message thread. If it's the message-thread that's calling this method, then the function will just be called; if another thread is calling, a message will be posted to the queue, and this method will block until that message is delivered, the function is called, and the result is returned.

Be careful not to cause any deadlocks with this! It's easy to do - e.g. if the caller thread has a critical section locked, which an unrelated message callback then tries to lock before the message thread gets round to processing this callback.

Parameters

callback	the function to call - its signature must be void* myCallbackFunction (void*)
userData	a user-defined pointer that will be passed to the function that gets called

Returns

the value that the callback function returns.

See also

MessageManagerLock

isThisTheMessageThread()

bool MessageManager::isThisTheMessageThread ( ) const

noexcept

Returns true if the caller-thread is the message thread.

setCurrentThreadAsMessageThread()

void MessageManager::setCurrentThreadAsMessageThread

(

)

Called to tell the manager that the current thread is the one that's running the dispatch loop.

(Best to ignore this method unless you really know what you're doing..)

See also

getCurrentMessageThread

getCurrentMessageThread()

Thread::ThreadID MessageManager::getCurrentMessageThread ( ) const

noexcept

Returns the ID of the current message thread, as set by setCurrentThreadAsMessageThread().

(Best to ignore this method unless you really know what you're doing..)

See also

setCurrentThreadAsMessageThread

currentThreadHasLockedMessageManager()

bool MessageManager::currentThreadHasLockedMessageManager ( ) const

noexcept

Returns true if the caller thread has currently got the message manager locked.

see the MessageManagerLock class for more info about this.

This will be true if the caller is the message thread, because that automatically gains a lock while a message is being dispatched.

existsAndIsLockedByCurrentThread()

static bool MessageManager::existsAndIsLockedByCurrentThread ( )

staticnoexcept

Returns true if there's an instance of the MessageManager, and if the current thread has the lock on it.

existsAndIsCurrentThread()

static bool MessageManager::existsAndIsCurrentThread ( )

staticnoexcept

Returns true if there's an instance of the MessageManager, and if the current thread is running it.

broadcastMessage()

static void MessageManager::broadcastMessage ( const String &  messageText )

static

Sends a message to all other JUCE applications that are running.

Parameters

messageText

the string that will be passed to the actionListenerCallback() method of the broadcast listeners in the other app.

See also

registerBroadcastListener, ActionListener

registerBroadcastListener()

void MessageManager::registerBroadcastListener

(

ActionListener *

listener

)

Registers a listener to get told about broadcast messages.

The actionListenerCallback() callback's string parameter is the message passed into broadcastMessage().

See also

broadcastMessage

deregisterBroadcastListener()

void MessageManager::deregisterBroadcastListener

(

ActionListener *

listener

)

Deregisters a broadcast listener.

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The documentation for this class was generated from the following file:

• juce_MessageManager.h