The QAbstractEventDispatcher class provides an interface to manage Qt's event queue. More...

#include <qabstracteventdispatcher.h>

Inheritance diagram for QAbstractEventDispatcher:

Public Types
typedef bool(*	EventFilter) (void *message)
	Typedef for a function with the signature. More...

typedef QPair< int, int >	TimerInfo
	Typedef for QPair<int, int>. More...

Signals
void	aboutToBlock ()
	This signal is emitted before the event loop calls a function that could block. More...

void	awake ()
	This signal is emitted after the event loop returns from a function that could block. More...

Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...

Public Functions
virtual void	closingDown ()

bool	filterEvent (void *message)
	Sends message through the event filter that was set by setEventFilter(). More...

virtual void	flush ()=0
	Flushes the event queue. More...

virtual bool	hasPendingEvents ()=0
	Returns true if there is an event waiting; otherwise returns false. More...

virtual void	interrupt ()=0
	Interrupts event dispatching; i. More...

virtual bool	processEvents (QEventLoop::ProcessEventsFlags flags)=0
	Processes pending events that match flags until there are no more events to process. More...

	QAbstractEventDispatcher (QObject *parent=0)
	Constructs a new event dispatcher with the given parent. More...

virtual QList< TimerInfo >	registeredTimers (QObject *object) const =0
	Returns a list of registered timers for object. More...

virtual void	registerSocketNotifier (QSocketNotifier *notifier)=0
	Registers notifier with the event loop. More...

int	registerTimer (int interval, QObject *object)
	Registers a timer with the specified interval for the given object. More...

virtual void	registerTimer (int timerId, int interval, QObject *object)=0
	Register a timer with the specified timerId and interval for the given object. More...

EventFilter	setEventFilter (EventFilter filter)
	Replaces the event filter function for this QAbstractEventDispatcher with filter and returns the replaced event filter function. More...

virtual void	startingUp ()

virtual void	unregisterSocketNotifier (QSocketNotifier *notifier)=0
	Unregisters notifier from the event dispatcher. More...

virtual bool	unregisterTimer (int timerId)=0
	Unregisters the timer with the given timerId. More...

virtual bool	unregisterTimers (QObject *object)=0
	Unregisters all the timers associated with the given object. More...

virtual void	wakeUp ()=0
	Wakes up the event loop. More...

	~QAbstractEventDispatcher ()
	Destroys the event dispatcher. More...

Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...

const QObjectList &	children () const
	Returns a list of child objects. More...

bool	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=0, const QObject receiver=0, const char *member=0)

bool	disconnect (const QObject receiver, const char member=0)

void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...

void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...

QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...

virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...

virtual bool	eventFilter (QObject , QEvent )
	Filters events if this object has been installed as an event filter for the watched object. More...

template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...

template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...

template<typename T >
QList< T >	findChildren (const QRegExp &re) const

bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...

void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...

bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...

void	killTimer (int id)
	Kills the timer with timer identifier, id. More...

virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...

QString	objectName () const

QObject *	parent () const
	Returns a pointer to the parent object. More...

QVariant	property (const char *name) const
	Returns the value of the object's name property. More...

Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...

void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...

void	setObjectName (const QString &name)

void	setParent (QObject *)
	Makes the object a child of parent. More...

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...

void	setUserData (uint id, QObjectUserData *data)

bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...

int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...

QThread *	thread () const
	Returns the thread in which the object lives. More...

QObjectUserData *	userData (uint id) const

virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Static Public Functions
static QAbstractEventDispatcher *	instance (QThread *thread=0)
	Returns a pointer to the event dispatcher object for the specified thread. More...

Static Public Functions inherited from QObject
static bool	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...

static bool	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	Disconnects signal in object sender from method in object receiver. More...

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static uint	registerUserData ()

static QString	tr (const char sourceText, const char comment=0, int n=-1)

static QString	trUtf8 (const char sourceText, const char comment=0, int n=-1)

Protected Functions
	QAbstractEventDispatcher (QAbstractEventDispatcherPrivate &, QObject *parent)

Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...

virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...

virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...

virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...

	QObject (QObjectPrivate &dd, QObject *parent=0)

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...

QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...

Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject

Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()

T *	qobject_cast (QObject *object)

	QObjectList

void *	qt_find_obj_child (QObject parent, const char type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QAbstractEventDispatcher class provides an interface to manage Qt's event queue.

An event dispatcher receives events from the window system and other sources. It then sends them to the QCoreApplication or QApplication instance for processing and delivery. QAbstractEventDispatcher provides fine-grained control over event delivery.

For simple control of event processing use QCoreApplication::processEvents().

For finer control of the application's event loop, call instance() and call functions on the QAbstractEventDispatcher object that is returned. If you want to use your own instance of QAbstractEventDispatcher or of a QAbstractEventDispatcher subclass, you must create your instance before you create the QApplication object.

The main event loop is started by calling QCoreApplication::exec(), and stopped by calling QCoreApplication::exit(). Local event loops can be created using QEventLoop.

Programs that perform long operations can call processEvents() with a bitwise OR combination of various QEventLoop::ProcessEventsFlag values to control which events should be delivered.

QAbstractEventDispatcher also allows the integration of an external event loop with the Qt event loop. For example, the Motif Extension includes a reimplementation of QAbstractEventDispatcher that merges Qt and Motif events together.

See also: QEventLoop, QCoreApplication

Definition at line 58 of file qabstracteventdispatcher.h.

Typedefs

◆ EventFilter

QAbstractEventDispatcher::EventFilter

Typedef for a function with the signature.

bool myEventFilter(void *message);

Note that the type of the message is platform dependent. The following table shows the {message}'s type on Windows, Mac, X11 and BlackBerry. You can do a static cast to these types.

Platform	type
Windows	MSG
X11	XEvent
Mac	NSEvent
BlackBerry	bps_event_t

See also: setEventFilter(), filterEvent()

Definition at line 90 of file qabstracteventdispatcher.h.

◆ TimerInfo

QAbstractEventDispatcher::TimerInfo

Typedef for QPair<int, int>.

The first component of the pair is the timer ID; the second component is the interval.

See also: registeredTimers()

Definition at line 64 of file qabstracteventdispatcher.h.

Constructors and Destructors

◆ QAbstractEventDispatcher() [1/2]

QAbstractEventDispatcher::QAbstractEventDispatcher ( QObject * parent = 0 )

explicit

Constructs a new event dispatcher with the given parent.

Definition at line 281 of file qabstracteventdispatcher.cpp.

     : QObject(*new QAbstractEventDispatcherPrivate, parent)
 {
     Q_D(QAbstractEventDispatcher);
     d->init();
 }

◆ ~QAbstractEventDispatcher()

QAbstractEventDispatcher::~QAbstractEventDispatcher ( )

Destroys the event dispatcher.

Definition at line 302 of file qabstracteventdispatcher.cpp.

303 { }

◆ QAbstractEventDispatcher() [2/2]

QAbstractEventDispatcher::QAbstractEventDispatcher	(	QAbstractEventDispatcherPrivate &	dd,
		QObject *	parent
	)

protected

Warning: This function is not part of the public interface.

Definition at line 291 of file qabstracteventdispatcher.cpp.

     : QObject(dd, parent)
 {
     Q_D(QAbstractEventDispatcher);
     d->init();
 }

Functions

◆ aboutToBlock

void QAbstractEventDispatcher::aboutToBlock ( )

signal

This signal is emitted before the event loop calls a function that could block.

See also: awake()

Referenced by QEventDispatcherGlib::processEvents(), QEventDispatcherUNIX::processEvents(), QEventDispatcherBlackberry::select(), and QEventDispatcherMacPrivate::waitingObserverCallback().

◆ awake

void QAbstractEventDispatcher::awake ( )

signal

This signal is emitted after the event loop returns from a function that could block.

See also: wakeUp() aboutToBlock()

Referenced by QEventDispatcherGlib::processEvents(), QEventDispatcherWin32::processEvents(), QEventDispatcherUNIX::processEvents(), QEventDispatcherBlackberry::select(), and QEventDispatcherMacPrivate::waitingObserverCallback().

◆ closingDown()

void QAbstractEventDispatcher::closingDown ( )

virtual

Warning: This function is not part of the public interface.

Reimplemented in QEventDispatcherWin32, QEventDispatcherQWS, and QEventDispatcherX11.

Definition at line 466 of file qabstracteventdispatcher.cpp.

Referenced by QThreadPrivate::finish(), and QCoreApplication::~QCoreApplication().

467 { }

◆ filterEvent()

bool QAbstractEventDispatcher::filterEvent ( void * message )

Sends message through the event filter that was set by setEventFilter().

If no event filter has been set, this function returns false; otherwise, this function returns the result of the event filter function.

Subclasses of QAbstractEventDispatcher must call this function for all messages received from the system to ensure compatibility with any extensions that may be used in the application.

Note that the type of message is platform dependent. See QAbstractEventDispatcher::EventFilter for details.

See also: setEventFilter()

Definition at line 560 of file qabstracteventdispatcher.cpp.

Referenced by QX11Data::clipboardWaitForEvent(), QX11Data::dndEnable(), QEventDispatcherX11::processEvents(), QEventDispatcherQWS::processEvents(), QEventDispatcherQPA::processEvents(), qwsEventSourceDispatch(), QEventDispatcherBlackberry::select(), userEventSourceDispatch(), and x11EventSourceDispatch().

 {
     Q_D(QAbstractEventDispatcher);
     if (d->event_filter) {
         // Raise the loopLevel so that deleteLater() calls in or triggered
         // by event_filter() will be processed from the main event loop.
         QScopedLoopLevelCounter loopLevelCounter(d->threadData);
         return d->event_filter(message);
     }
     return false;
 }

◆ flush()

void QAbstractEventDispatcher::flush ( )

pure virtual

Flushes the event queue.

This normally returns almost immediately. Does nothing on platforms other than X11.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, QEventDispatcherQPA, QEventDispatcherQWS, QEventDispatcherX11, QGuiEventDispatcherGlib, and QEventDispatcherBlackberryQPA.

◆ hasPendingEvents()

bool QAbstractEventDispatcher::hasPendingEvents ( )

pure virtual

Returns true if there is an event waiting; otherwise returns false.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, QEventDispatcherQPA, QEventDispatcherQWS, QEventDispatcherX11, and QEventDispatcherBlackberryQPA.

Referenced by QCoreApplication::hasPendingEvents().

◆ instance()

QAbstractEventDispatcher * QAbstractEventDispatcher::instance ( QThread * thread = 0 )

static

Returns a pointer to the event dispatcher object for the specified thread.

If thread is zero, the current thread is used. If no event dispatcher exists for the specified thread, this function returns 0.

Note: If Qt is built without thread support, the thread argument is ignored.

Definition at line 314 of file qabstracteventdispatcher.cpp.

Referenced by QAxWidget::clear(), QX11Data::clipboardWaitForEvent(), QAxWidget::createHostWindow(), QClassFactory::CreateInstanceHelper(), QX11Data::dndEnable(), QEventDispatcherMac::flush(), QCoreApplication::hasPendingEvents(), QBBEngine::initialize(), QHostInfo::lookupHost(), QBBIntegration::QBBIntegration(), qt_GetMessageHook(), qt_x11_wait_for_window_manager(), QWaylandDisplay::QWaylandDisplay(), QXcbConnection::QXcbConnection(), QNSOpenSavePanelDelegate::runApplicationModalPanel, QWidgetPrivate::show_sys(), QBenchmarkEvent::start(), QBasicTimer::stop(), QBenchmarkEvent::stop(), QETWidget::translateMouseEvent(), QBBEngine::~QBBEngine(), and QEventDispatcherMac::~QEventDispatcherMac().

 {
     QThreadData *data = thread ? QThreadData::get2(thread) : QThreadData::current();
     return data->eventDispatcher;
 }

◆ interrupt()

void QAbstractEventDispatcher::interrupt ( )

pure virtual

Interrupts event dispatching; i.

e. the event dispatcher will return from processEvents() as soon as possible.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, and QEventDispatcherGlib.

Referenced by QEventDispatcherMac::flush(), QNSOpenSavePanelDelegate::runApplicationModalPanel, QWidgetPrivate::show_sys(), and QEventDispatcherMac::~QEventDispatcherMac().

◆ processEvents()

bool QAbstractEventDispatcher::processEvents ( QEventLoop::ProcessEventsFlags flags )

pure virtual

Processes pending events that match flags until there are no more events to process.

Returns true if an event was processed; otherwise returns false.

This function is especially useful if you have a long running operation and want to show its progress without allowing user input; i.e. by using the QEventLoop::ExcludeUserInputEvents flag.

If the QEventLoop::WaitForMoreEvents flag is set in flags, the behavior of this function is as follows:

If events are available, this function returns after processing them.
If no events are available, this function will wait until more are available and return after processing newly available events.

If the QEventLoop::WaitForMoreEvents flag is not set in flags, and no events are available, this function will return immediately.

Note: This function does not process events continuously; it returns after all available events are processed.

See also: hasPendingEvents()

Implemented in QGuiEventDispatcherWin32, QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, QPAEventDispatcherGlib, QWSEventDispatcherGlib, QEventDispatcherQPA, QEventDispatcherQWS, QEventDispatcherX11, QGuiEventDispatcherGlib, and QEventDispatcherBlackberryQPA.

Referenced by QX11Data::clipboardWaitForEvent(), and QCoreApplication::processEvents().

◆ registeredTimers()

QList< TimerInfo > QAbstractEventDispatcher::registeredTimers ( QObject * object ) const

pure virtual

Returns a list of registered timers for object.

The timer ID is the first member in each pair; the interval is the second.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, and QEventDispatcherGlib.

Referenced by QObject::event().

◆ registerSocketNotifier()

void QAbstractEventDispatcher::registerSocketNotifier ( QSocketNotifier * notifier )

pure virtual

Registers notifier with the event loop.

Subclasses must implement this method to tie a socket notifier into another event loop.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, QEventDispatcherQPA, and QEventDispatcherBlackberry.

◆ registerTimer() [1/2]

int QAbstractEventDispatcher::registerTimer	(	int	interval,
		QObject *	object
	)

Registers a timer with the specified interval for the given object.

Definition at line 387 of file qabstracteventdispatcher.cpp.

Referenced by QObject::startTimer().

 {
     int id = QAbstractEventDispatcherPrivate::allocateTimerId();
     registerTimer(id, interval, object);
     return id;
 }

◆ registerTimer() [2/2]

void QAbstractEventDispatcher::registerTimer	(	int	timerId,
		int	interval,
		QObject *	object
	)

pure virtual

Register a timer with the specified timerId and interval for the given object.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, and QEventDispatcherGlib.

◆ setEventFilter()

QAbstractEventDispatcher::EventFilter QAbstractEventDispatcher::setEventFilter ( EventFilter filter )

Replaces the event filter function for this QAbstractEventDispatcher with filter and returns the replaced event filter function.

Only the current event filter function is called. If you want to use both filter functions, save the replaced EventFilter in a place where yours can call it.

The event filter function set here is called for all messages taken from the system event loop before the event is dispatched to the respective target, including the messages not meant for Qt objects.

The event filter function should return true if the message should be filtered, (i.e. stopped). It should return false to allow processing the message to continue.

By default, no event filter function is set (i.e., this function returns a null EventFilter the first time it is called).

Definition at line 536 of file qabstracteventdispatcher.cpp.

Referenced by QAxWidget::clear(), QAxWidget::createHostWindow(), QClassFactory::CreateInstanceHelper(), QBBEngine::initialize(), QBenchmarkEvent::start(), QBenchmarkEvent::stop(), and QBBEngine::~QBBEngine().

 {
     Q_D(QAbstractEventDispatcher);
     EventFilter oldFilter = d->event_filter;
     d->event_filter = filter;
     return oldFilter;
 }

◆ startingUp()

void QAbstractEventDispatcher::startingUp ( )

virtual

Warning: This function is not part of the public interface.

Reimplemented in QEventDispatcherWin32, QEventDispatcherQWS, QEventDispatcherX11, QWSEventDispatcherGlib, and QGuiEventDispatcherGlib.

Definition at line 462 of file qabstracteventdispatcher.cpp.

Referenced by QThreadPrivate::createEventDispatcher(), QCoreApplication::QCoreApplication(), and qt_adopted_thread_watcher_function().

463 { }

◆ unregisterSocketNotifier()

void QAbstractEventDispatcher::unregisterSocketNotifier ( QSocketNotifier * notifier )

pure virtual

Unregisters notifier from the event dispatcher.

Subclasses must reimplement this method to tie a socket notifier into another event loop. Reimplementations must call the base implementation.

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, QEventDispatcherQPA, and QEventDispatcherBlackberry.

◆ unregisterTimer()

bool QAbstractEventDispatcher::unregisterTimer ( int timerId )

pure virtual

Unregisters the timer with the given timerId.

Returns true if successful; otherwise returns false.

See also: registerTimer(), unregisterTimers()

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, and QEventDispatcherGlib.

Referenced by QObject::killTimer(), and QBasicTimer::stop().

◆ unregisterTimers()

bool QAbstractEventDispatcher::unregisterTimers ( QObject * object )

pure virtual

Unregisters all the timers associated with the given object.

Returns true if all timers were successful removed; otherwise returns false.

See also: unregisterTimer(), registeredTimers()

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, and QEventDispatcherGlib.

Referenced by QObject::event(), and QObjectPrivate::~QObjectPrivate().

◆ wakeUp()

void QAbstractEventDispatcher::wakeUp ( )

pure virtual

Wakes up the event loop.

Note: This class or function is threadsafe.

See also: awake()

Implemented in QEventDispatcherUNIX, QEventDispatcherMac, QEventDispatcherWin32, QEventDispatcherGlib, and QEventDispatcherBlackberry.

Referenced by QWindowSystemInterfacePrivate::queueWindowSystemEvent(), QCoreApplicationPrivate::sendPostedEvents(), and QObjectPrivate::setThreadData_helper().

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

/src/corelib/kernel/qabstracteventdispatcher.h
/src/corelib/kernel/qabstracteventdispatcher.cpp

Public Types

Signals

Public Functions

Static Public Functions

Protected Functions

Additional Inherited Members

Detailed Description

Typedefs

◆ EventFilter

◆ TimerInfo

Constructors and Destructors

◆ QAbstractEventDispatcher() [1/2]

◆ ~QAbstractEventDispatcher()

◆ QAbstractEventDispatcher() [2/2]

Functions

◆ aboutToBlock

◆ awake

◆ closingDown()

◆ filterEvent()

◆ flush()

◆ hasPendingEvents()

◆ instance()

◆ interrupt()

◆ processEvents()

◆ registeredTimers()

◆ registerSocketNotifier()

◆ registerTimer() [1/2]

◆ registerTimer() [2/2]

◆ setEventFilter()

◆ startingUp()

◆ unregisterSocketNotifier()

◆ unregisterTimer()

◆ unregisterTimers()

◆ wakeUp()