JUCE  v5.4.1-191-g0ab5e696f
JUCE API
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juce::MessageManager Class Referencefinal

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

#include <juce_MessageManager.h>

Collaboration diagram for juce::MessageManager:

Classes

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

Static Public Member Functions

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

Private Member Functions

 MessageManager () noexcept
 

Static Private Member Functions

static bool dispatchNextMessageOnSystemQueue (bool returnIfNoPendingMessages)
 
static void doPlatformSpecificInitialisation ()
 
static void doPlatformSpecificShutdown ()
 
static void * exitModalLoopCallback (void *)
 
static bool postMessageToSystemQueue (MessageBase *)
 

Private Attributes

std::unique_ptr< ActionBroadcasterbroadcaster
 
Thread::ThreadID messageThreadId
 
Atomic< intquitMessagePosted { 0 }
 
Atomic< intquitMessageReceived { 0 }
 
Atomic< Thread::ThreadIDthreadWithLock
 

Static Private Attributes

static MessageManagerinstance
 

Friends

class MessageBase
 
class MessageManagerLock
 
class QuitMessage
 

Detailed Description

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

See also
Message, CallbackMessage, MessageManagerLock, JUCEApplication, JUCEApplicationBase

{Events}

Constructor & Destructor Documentation

◆ MessageManager()

juce::MessageManager::MessageManager ( )
privatenoexcept

Member Function Documentation

◆ broadcastMessage()

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

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

Parameters
messageTextthe string that will be passed to the actionListenerCallback() method of the broadcast listeners in the other app.
See also
registerBroadcastListener, ActionListener

◆ callAsync()

template<typename FunctionType >
static void juce::MessageManager::callAsync ( FunctionType  functionToCall)
inlinestatic

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

◆ callFunctionOnMessageThread()

void* juce::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
callbackthe function to call - its signature must be
void* myCallbackFunction (void*)
userDataa user-defined pointer that will be passed to the function that gets called
Returns
the value that the callback function returns.
See also
MessageManagerLock

◆ currentThreadHasLockedMessageManager()

bool juce::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.

◆ deleteInstance()

static void juce::MessageManager::deleteInstance ( )
static

Deletes the global MessageManager instance.

Does nothing if no instance had been created.

◆ deregisterBroadcastListener()

void juce::MessageManager::deregisterBroadcastListener ( ActionListener listener)

Deregisters a broadcast listener.

◆ dispatchNextMessageOnSystemQueue()

static bool juce::MessageManager::dispatchNextMessageOnSystemQueue ( bool  returnIfNoPendingMessages)
staticprivate

◆ doPlatformSpecificInitialisation()

static void juce::MessageManager::doPlatformSpecificInitialisation ( )
staticprivate

◆ doPlatformSpecificShutdown()

static void juce::MessageManager::doPlatformSpecificShutdown ( )
staticprivate

◆ existsAndIsCurrentThread()

static bool juce::MessageManager::existsAndIsCurrentThread ( )
staticnoexcept

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

◆ existsAndIsLockedByCurrentThread()

static bool juce::MessageManager::existsAndIsLockedByCurrentThread ( )
staticnoexcept

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

◆ exitModalLoopCallback()

static void* juce::MessageManager::exitModalLoopCallback ( void *  )
staticprivate

◆ getCurrentMessageThread()

Thread::ThreadID juce::MessageManager::getCurrentMessageThread ( ) const
inlinenoexcept

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

◆ getInstance()

static MessageManager* juce::MessageManager::getInstance ( )
static

Returns the global instance of the MessageManager.

◆ getInstanceWithoutCreating()

static MessageManager* juce::MessageManager::getInstanceWithoutCreating ( )
staticnoexcept

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

◆ hasStopMessageBeenSent()

bool juce::MessageManager::hasStopMessageBeenSent ( ) const
inlinenoexcept

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

◆ isThisTheMessageThread()

bool juce::MessageManager::isThisTheMessageThread ( ) const
noexcept

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

◆ postMessageToSystemQueue()

static bool juce::MessageManager::postMessageToSystemQueue ( MessageBase )
staticprivate

◆ registerBroadcastListener()

void juce::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

◆ runDispatchLoop()

void juce::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

◆ runDispatchLoopUntil()

bool juce::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.

◆ setCurrentThreadAsMessageThread()

void juce::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

◆ stopDispatchLoop()

void juce::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

Friends And Related Function Documentation

◆ MessageBase

friend class MessageBase
friend

◆ MessageManagerLock

friend class MessageManagerLock
friend

◆ QuitMessage

friend class QuitMessage
friend

Member Data Documentation

◆ broadcaster

std::unique_ptr<ActionBroadcaster> juce::MessageManager::broadcaster
private

◆ instance

MessageManager* juce::MessageManager::instance
staticprivate

◆ messageThreadId

Thread::ThreadID juce::MessageManager::messageThreadId
private

◆ quitMessagePosted

Atomic<int> juce::MessageManager::quitMessagePosted { 0 }
private

◆ quitMessageReceived

Atomic<int> juce::MessageManager::quitMessageReceived { 0 }
private

◆ threadWithLock

Atomic<Thread::ThreadID> juce::MessageManager::threadWithLock
private

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