Constructs an object with parent object parent. The parent of an object may be viewed as the object's owner. For instance, a dialog box is the parent of the OK and Cancel buttons it contains.

The destructor of a parent object destroys all child objects. Setting the given parent to nullptr constructs an object with no parent. If the object is a widget it will become a top-level window.

See also

parent(), findChild(), findChildren()

Destroys the object deleting all of its child objects.

All signals to and from the object are automatically disconnected and any pending posted events for the object are removed from the event queue. It is often safer to use deleteLater() rather than deleting a QObject subclass directly.

Warning

All child objects are deleted. If any of these objects are on the stack or global your program may crash. It is not advised to retain pointers to child objects from outside the parent. The destroyed() signal allows you to detect when an object is destroyed.

Deleting a QObject while pending events are waiting to be delivered can cause a crash. You must not delete the QObject directly if it exists in a different thread than the one currently executing. Use deleteLater() instead which will cause the event loop to delete the object after all pending events have been delivered to it.

See also

deleteLater()

If block is true signals emitted by this object are blocked. Emitting a signal will not invoke anything connected to it. The return value is the previous value of signalsBlocked(). The destroyed() signal will be emitted even if the signals for this object have been blocked.

See also

signalsBlocked()

This event handler can be overridden in a subclass to receive child events. The event is passed as the event parameter.

QEvent::ChildAdded and QEvent::ChildRemoved events are sent to objects when children are added or removed. For both events the child is either a QObject or QWidget. In the ChildAdded event the child is not yet fully constructed and in the ChildRemoved even it might be partially destroyed.

QEvent::ChildPolished events are sent to widgets when children are polished or when polished children are added. If you receive a child polished event the child's construction is usually completed. However this is not guaranteed and multiple polish events may be delivered during the execution of a widget's constructor.

For every child widget, one ChildAdded event and one ChildRemoved event will be received. Between the add and remove events there may be any number of ChildPolished events.

The ChildPolished event is omitted if a child is removed immediately after it is added. If a child is polished several times during construction and destruction you may receive several child polished events for the same child, each time with a different virtual table.

See also

event()

Returns a list of child objects. The first child added is the first object in the list and the last child added is the last object in the list. New children are appended at the end.

The list order changes whenever QWidget children are moved in the Z order, causing them to be raised or lowered. A widget that is raised becomes the last object in the list and a widget that is lowered becomes the first object in the list.

See also

findChild(), findChildren(), parent(), setParent()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in the receiver object. Returns true if the connection succeeds, otherwise returns false. The type parameter describes the type of connection to establish.

See also

disconnect()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in the receiver object. The method returns true if it successfully connects the signal to the slot. This method will return false if it can not create the connection. For example, if QObject is unable to find the signalMethod or the slotMethod, or if their signatures are not compatible.

A signal/slot connection is automatically disconnected when either the sender or the receiver object are destroyed.

The type parameter describes the type of connection to establish. It specifies whether the signal is delivered to a slot immediately or queued for delivery at a later time. If you pass the Qt::UniqueConnection type, the connection will only be made if it is not a duplicate. The default is an auto connection.

The location is a string which is used as part of the error message if the connection fails. The default value is an empty QString.

To use this version of connect() use the SIGNAL() and SLOT() macros when specifying the signalMethod and the slotMethod. To use method pointers refer to other versions of the connect method.

The following example ensures the label always displays the current scroll bar value.

The signal and slots parameters must not contain any parameter names, only data types. The following example shows an incorrect usage of the SIGNAL and SLOT macros. The connection will always fail at runtime.

A signal can also be connected to another signal as shown in the following example.

In the preceding example the MyWidget constructor relays a signal from a private member variable and makes it available under a name that relates to MyWidget.

Multiple Connections

A given signal can be connected to multiple signals or multiple slots.

• Any number of signals can be connected to one slot.

• If a signal is connected to several slots, when the signal is emitted the slots are invoked in the order they were connected

• All of these connections can be disconnected with one single disconnect() call.

See also

disconnect(), sender(), CS_DECLARE_METATYPE()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in the receiver object. Returns true if the connection succeeds, otherwise returns false. The type parameter describes the type of connection to establish. The location is a string which is used as part of the error message if the connection fails. A value must be supplied.

See also

disconnect()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in this object. Returns true if the connection succeeds, otherwise returns false. The type parameter describes the type of connection to establish. The location is a string which is used as part of the error message if the connection fails. A value must be supplied.

Equivalent to calling connect(sender, signalMethod, location, this, slotMethod, type).

See also

disconnect()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in this object. Returns true if the connection succeeds, otherwise returns false. The type parameter describes the type of connection to establish.

Equivalent to calling connect(sender, signalMethod, this, slotMethod, type).

See also

disconnect()

Creates a connection of the given type from the signalMethod in the sender object to the slotMethod in the receiver object. Returns true if the connection succeeds, otherwise returns false.

See also

disconnect()

Creates a connection of the given type from the signalMethod in the sender object to the slotLambda in receiver object. Returns true if the connection succeeds, otherwise returns false.

In this version the slot must be a function object or lambda expression.

See also

disconnect()

This method is called when a connection has been made to signalMethod in this object.

See also

connect(), disconnectNotify()

Reimplemented in QBuffer::connectNotify(), QNetworkSession::connectNotify(), QFutureWatcherBase::connectNotify()

This event handler can be reimplemented in a subclass to receive custom events. Custom events are user-defined events with a type greeter than or equal to QEvent::User. The event is passed in the event parameter.

See also

event(), QEvent

Schedules this object for deletion.

The object will be deleted when control returns to the event loop. If the event loop is not running when this method is called (e.g. deleteLater() is called on an object before QCoreApplication::exec()), the object will be deleted once the event loop is started. If deleteLater() is called after the main event loop has stopped, the object will not be deleted. If deleteLater() is called on an object that lives in a thread with no running event loop, the object will be destroyed when the thread finishes.

Entering and leaving a new event loop by opening a modal dialog or similar actions will not perform the deferred deletion. For the object to be deleted the control must return to the event loop from which deleteLater() was called.

Note

It is safe to call this method more than once. When the first deferred deletion event is delivered, any pending events for the object are removed from the event queue.

See also

destroyed(), QPointer

This signal is emitted immediately before the object obj is destroyed, and can not be blocked. All the object's children are destroyed immediately after this signal is emitted.

See also

deleteLater(), QPointer

Disconnects all signals in this object from the slotMethod in the receiver. If the slotMethod is an empty QString then all slots in the receiver will be disconnected.

See also

connect()

Disconnects the signalMethod in the sender from the slotMethod in the receiver. Returns true if the disconnection is successful, otherwise returns false. A nullptr can not be passed as the sender.

This method will fail under the following conditions:

1. signal is not a member of sender class or one of its parent classes
2. method is not a member of receiver class or one of its parent classes
3. signal is not actually a signal

QMetaMethod() may be passed as the signal or method to indicate "any signal" or "any slot". Nullptr may be passed as the receiver to indicate "any receiver".

See also

connect()

Disconnects the signalMethod in the sender from the slotMethod in the receiver. Returns true if the connection is successfully disconnected, otherwise returns false.

This method is typically called in one of the following ways.

1. Disconnect all slots connected to signals in myObject.

   disconnect(myObject, nullptr, nullptr, nullptr);

   The preceding is equivalent to the non-static overloaded method:

   myObject->disconnect();

2. Disconnect all slots connected to a specific signal.

   disconnect(myObject, SIGNAL(mySignal()), nullptr, nullptr);

   The preceding is equivalent to the non-static overloaded method:

   myObject->disconnect(SLOT(mySignal()));

3. Disconnect a specific receiver:

   disconnect(myObject, nullptr, myReceiver, nullptr);

   This is equivalent to the non-static overloaded method:

   myObject->disconnect(myReceiver);

Multiple Connections

Multiple connections can be disconnected at one time.

• The sender may never be a nullptr. You can not disconnect signals from more than one sender in a single call.

• If signalMethod is an empty QString or a nullptr then all signals in the sender will be disconnected.

• If the receiver parameter is a nullptr then all receivers will be disconnected.

• If the slotMethod is an empty QString or a nullptr then all slots in the receiver will be disconnected.

See also

connect()

Disconnects the signalMethod in the sender object from the slotMethod in the receiver object. The location is a string which is used as part of the error message if the connection fails. A value must be supplied.

Returns true if the connection is successfully disconnected, otherwise returns false.

See also

connect()

Disconnects all signals and slots for the given sender and receiver.

Disconnects the signalMethod in the sender object from the slotMethod in the receiver object. The location is a string which is used as part of the error message if the connection fails. The default is an empty QString. If the receiver parameter is a nullptr then all receivers will be disconnected.

Returns true if the connection is successfully disconnected, otherwise returns false.

See also

connect()

Disconnects the signalMethod from the slotMethod for the given receiver. If the receiver parameter is a nullptr then all receivers will be disconnected. If the slotMethod is an empty QString then all slots in the receiver will be disconnected.

See also

connect()

Disconnects the signalMethod in the sender from the slotMethod in the receiver.

See also

connect()

Disconnects the signalMethod in the sender from all slot methods in the receiver.

See also

connect()

Disconnects the signalMethod in the sender object from the slotMethod in the receiver object. Returns true if the connection succeeds, otherwise returns false. In this version the slot must be a function object or lambda expression.

See also

connect()

This method is called when a slot is disconnected from signalMethod in this object.

See also

disconnect(), connectNotify()

Reimplemented in QBuffer::disconnectNotify(), QNetworkSession::disconnectNotify(), QFutureWatcherBase::disconnectNotify()

Dumps information about signal connections, etc. for this object to the debug output. This method is useful for debugging but does nothing if CopperSpice has been compiled with debugging turned off.

See also

dumpObjectTree()

Dumps a tree of children to the debug output. This method is useful for debugging but does nothing if CopperSpice has been compiled with debugging turned off.

See also

dumpObjectInfo()

Returns the names of all properties which have been dynamically added to the object using setProperty().

Receives events to an object and should return true if the given event was recognized and processed. This method can be overridden to customize the event handling for an object.

See also

installEventFilter(), timerEvent(), QApplication::sendEvent(), QApplication::postEvent(), QWidget::event()

Reimplemented in QApplication::event(), QWebPage::event(), QGraphicsScene::event(), QAction::event(), QWebFrame::event(), QStateMachine::event(), QCompleter::event(), QSettings::event(), QFileSystemModel::event(), QAbstractAnimation::event(), QSystemTrayIcon::event(), QState::event(), QAbstractTransition::event(), QMacStyle::event(), QVariantAnimation::event(), QProxyStyle::event(), QShortcut::event(), QHistoryState::event(), QThread::event(), QAbstractState::event(), QSignalTransition::event(), QEventTransition::event(), QSequentialAnimationGroup::event(), QSocketNotifier::event(), QPropertyAnimation::event(), QFutureWatcherBase::event(), QAnimationGroup::event(), QPauseAnimation::event(), QWinEventNotifier::event(), QWidgetAction::event(), QParallelAnimationGroup::event(), QFinalState::event(), QCoreApplication::event()

Filters events if this object has been installed as an event filter for the watched object. If you override this method and want to filter the event so it is ignored, return true.

In this example unhandled events are passed to the base class eventFilter() method.

Warning

If you delete the receiver object in this method be sure to return true. If not CopperSpice will forward the event to the deleted object and the program will crash.

See also

installEventFilter()

Reimplemented in QGraphicsScene::eventFilter(), QStateMachine::eventFilter(), QCompleter::eventFilter(), QItemDelegate::eventFilter(), QWindowsStyle::eventFilter(), QStyledItemDelegate::eventFilter(), QWidgetAction::eventFilter()

Returns the first child of this object which can be cast to type T and has the given childName. Returns nullptr if there is no such object. Omitting the childName argument causes all object names to be matched. The search is performed recursively.

If there is more than one child matching the search the most direct ancestor is returned. If there are several direct ancestors it is undefined which one will be returned. In that case findChildren() should be used.

This example returns a child QPushButton of parentWidget named "button1".

This example returns a QListWidget child of parentWidget:

See also

findChildren()

Returns all children of this object which can be cast to type T and have names matching the regular expression regExp. Returns an empty list if there are no such objects. The search is performed recursively unless options specifies the option FindDirectChildrenOnly.

Returns all children of this object which can be cast to type T and has the given childName. Returns an empty list if there are no such objects. Omitting the childName argument causes all object names to be matched. The search is performed recursively unless options specifies the option FindDirectChildrenOnly.

The following example shows how to find a list of child QWidgets of the specified parentWidget named "widgetname".

This example returns all QPushButtons that are children of parentWidget:

See also

findChild()

Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits from the given className, otherwise returns false.

A class is considered to inherit itself.

See also

metaObject(), qobject_cast()

Installs an event filter filterObj on this object.

An event filter is an object that receives all events that are sent to this object. The filter can either stop the event or forward it to this object. The event filter filterObj receives events via its eventFilter() method. The eventFilter() method must return true if the event should be filtered, otherwise it must return false.

If multiple event filters are installed on a single object the filter that was installed last is activated first.

The following example is a KeyPressFilter class which consumes the key presses of its monitored objects.

The following shows how to install the filter.

The filtering object must be in the same thread as this object. If filterObj is in a different thread this method does nothing. If either filterObj or this object are moved to a different thread after installing the filter, the event filter will not be called until both objects are in the same thread again.

Warning

If you delete the receiver object in your eventFilter() method be sure to return true. If you return false CopperSpice sends the event to the deleted object and the program will crash.

See also

removeEventFilter(), eventFilter(), event()

Returns true if the signal is connected to at least one receiver, otherwise returns false. The signalMethod must be a valid signal declared for the current object, otherwise the behavior is undefined.

The following code illustrates that you can use this method to avoid emitting a signal which no one is connected to. It is worth noting that this method does not conform to the object-oriented principle of modularity. However, it might be useful when you need to perform an expensive operation to emit the signal.

Returns true if the object is a widget, otherwise returns false. Equivalent to calling inherits("QWidget").

Returns true if the object is a window, otherwise returns false. Equivalent to calling inherits("QWindow"), except it is much faster.

Kills the timer with timer identifier id. The timer identifier is returned by startTimer() when a timer event is started.

See also

timerEvent(), startTimer()

Returns a pointer to the meta object of this object.

A meta object contains information about a class which inherits from QObject. Every QObject subclass that contains the CS_OBJECT macro will have a meta object. The meta object information is required by the signal/slot connection mechanism and the property system. The inherits() method also makes use of the meta object.

If you have no pointer to an actual object instance but still want to access the meta object of a class, you can use staticMetaObject().

See also

staticMetaObject()

Changes the thread affinity for this object and its children. The object can not be moved if it has a parent. Event processing will continue in the targetThread. To move an object to the main thread, use QApplication::instance() to retrieve a pointer to the current application, and then use QApplication::thread() to retrieve the thread in which the application lives.

If targetThread is zero, all event processing for this object and its children stops.

All active timers for the object will be reset. The timers are first stopped in the current thread and restarted (with the same interval) in the targetThread. As a result constantly moving an object between threads can postpone timer events indefinitely.

A QEvent::ThreadChange event is sent to this object just before the thread affinity is changed. You can handle this event to perform any special processing. Any new events which are posted to this object will be handled in the targetThread.

Warning

This method is not thread-safe. The current thread must be same as the current thread affinity. This method can only give away an object from the current thread to another thread, it can not steal an object from any arbitrary thread to the current thread.

See also

thread()

Returns the name of the current object.

This signal is emitted after the object's name has been changed. The new object name is passed as objectName.

Please be aware that this is a private signal. It can be used in signal connections but can not be emitted by the user. This is the Notifier signal for property objectName.

See also

QObject::objectName

Returns a pointer to the parent object.

See also

setParent(), children()

Returns the value of the property with the given name. If no such property exists a default constructed T is returned. Information about all available properties is provided through the metaObject() and dynamicPropertyNames().

See also

setProperty(), QVariant::isValid(), metaObject(), dynamicPropertyNames()

Returns the number of connections which exist for this signal.

When calling this method you can pass a string or the SLOT() macro to pass the name of the signal.

Removes an event filter object obj from this object. The request is ignored if such an event filter has not been installed.

All event filters for this object are automatically removed when this object is destroyed. It is always safe to remove an event filter, even during event filter activation. For example, from the eventFilter() method.

See also

installEventFilter(), eventFilter(), event()

Returns a pointer to the object that sent the signal, if called in a slot activated by a signal, otherwise it returns nullptr. The pointer is valid only during the execution of the slot that calls this method from this object's thread context.

The pointer returned by this method becomes invalid if the sender is destroyed, or if the slot is disconnected from the sender's signal.

See also

senderSignalIndex(), QSignalMapper

Returns the meta method index of the signal that called the currently executing slot, which is a member of the class returned by sender(). If called outside of a slot activated by a signal -1 is returned.

For signals with default parameters, this method will always return the index with all parameters, regardless of which was used with connect(). For example, the signal destroyed(QObject *obj = nullptr) will have two different indexes (with and without the parameter), but this method will always return the index with a parameter. This does not apply when overloading signals with different parameters.

See also

sender(), QMetaObject::indexOfSignal(), QMetaObject::method()

Sets the name of the current object.

Makes the object a child of parent.

See also

parent(), QWidget::setParent()

Sets the value of the property with the given name to value.

If the property is defined at compile time using CS_PROPERTY_READ() then setProperty() will return true. If the property is not defined it is added as a dynamic property and false is returned. Information about all available properties is provided through the metaObject() and dynamicPropertyNames().

Dynamic properties can be queried again using property() and can be removed by setting the property value to an invalid QVariant. Changing the value of a dynamic property causes a QDynamicPropertyChangeEvent to be sent to the object.

Note

Dynamic properties starting with "_q_" are reserved for internal purposes.

See also

property(), metaObject(), dynamicPropertyNames()

Returns true if signals are blocked, otherwise returns false. Signals are not blocked by default.

See also

blockSignals()

Starts a timer and returns a timer identifier. Returns zero if the timer could not be started. A timer event will occur every interval milliseconds until killTimer() is called. If interval is 0 then the timer event occurs once every time there are no more window system events to process.

If multiple timers are running the QTimerEvent::timerId() can be used to find out which timer was activated.

The virtual timerEvent() method is called with the QTimerEvent event parameter class when a timer event occurs. Reimplement this method to get timer events.

The QTimer's accuracy depends on the underlying operating system and hardware. Most platforms support an accuracy of 20 milliseconds, some provide more. If CopperSpice is unable to deliver the requested number of timer events, it will silently discard some.

The QTimer class provides a high-level programming interface with single-shot timers and timer signals instead of events. There is also a QBasicTimer class that is more lightweight than QTimer and less clumsy than using timer IDs directly.

See also

timerEvent(), killTimer(), QTimer::singleShot()

Returns the meta object for this class.

See also

metaObject()

Returns the thread in which this object lives.

See also

moveToThread()

This event handler can be overridden in a subclass to receive timer events for the object.

QTimer provides a higher level interface to the timer functionality and also more general information about timers. The timer event is passed in the event parameter.

See also

startTimer(), killTimer(), event()

Reimplemented in QTimer::timerEvent(), QTimeLine::timerEvent(), QFileSystemModel::timerEvent()

Returns a translated version of text which may be based on a comment string and the value of numArg for strings containing plurals. Returns the value for text if no appropriate translated string is available. If the same text has different meanings within the same context, an additional identifying string may be passed in comment.

Refer to Modifying Your Source Code for Translation for additional information.

See also

QApplication::translate(), Internationalization

Returns the given object cast to type T if the object is of type T or a subclass. If the object does not inherit from T returns nullptr. If object is passed as nullptr then it will return a nullptr.

The qobject_cast() method is the same as the standard C++ dynamic_cast().

See also

QObject::inherits()

Equivalent to QList<QObject *>.

This property holds the name of this object. You can find an object by name and type using findChild(). You can find a set of objects with findChildren(). By default this property contains an empty string.

See also

metaObject(), QMetaObject::className()