- Qt 5.15
- Qt Core
- C++ Classes
- QEventTransition
- Qt 5.15.18 Reference Documentation

# QEventTransition Class

The QEventTransition class provides a QObject-specific transition for Qt events. More...

Header: | #include <QEventTransition>
qmake: | QT += core
Since: | Qt 4.6
Inherits: | QAbstractTransition

This class was introduced in Qt 4.6.

- List of all members, including inherited members

## Properties

- eventSource : QObject*
- eventType : QEvent::Type

## Public Functions

| QEventTransition(QObject *object, QEvent::Type type, QState *sourceState = nullptr)
| QEventTransition(QState *sourceState = nullptr)
virtual | ~QEventTransition()
QObject * | eventSource() const
QEvent::Type | eventType() const
void | setEventSource(QObject *object)
void | setEventType(QEvent::Type type)

## Reimplemented Protected Functions

virtual bool | event(QEvent *e) override
virtual bool | eventTest(QEvent *event) override
virtual void | onTransition(QEvent *event) override

## Detailed Description

A QEventTransition object binds an event to a particular QObject. QEventTransition is part of The State Machine Framework.

Example:

     QPushButton *button = ...;
     QState *s1 = ...;
     QState *s2 = ...;
     // If in s1 and the button receives an Enter event, transition to s2
     QEventTransition *enterTransition = new QEventTransition(button, QEvent::Enter);
     enterTransition->setTargetState(s2);
     s1->addTransition(enterTransition);
     // If in s2 and the button receives an Exit event, transition back to s1
     QEventTransition *leaveTransition = new QEventTransition(button, QEvent::Leave);
     leaveTransition->setTargetState(s1);
     s2->addTransition(leaveTransition);

### Subclassing

When reimplementing the eventTest() function, you should first call the base implementation to verify that the event is a QStateMachine::WrappedEvent for the proper object and event type. You may then cast the event to a QStateMachine::WrappedEvent and get the original event by calling QStateMachine::WrappedEvent::event(), and perform additional checks on that object.

See also QState::addTransition().

## Property Documentation

### eventSource : QObject*

This property holds the event source that this event transition is associated with

Access functions:

QObject * | eventSource() const
void | setEventSource(QObject *object)

### eventType : QEvent::Type

This property holds the type of event that this event transition is associated with

Access functions:

QEvent::Type | eventType() const
void | setEventType(QEvent::Type type)

## Member Function Documentation

### QEventTransition::QEventTransition(QObject *object, QEvent::Type type, QState *sourceState = nullptr)

Constructs a new QEventTransition object associated with events of the given type for the given object, and with the given sourceState.

### QEventTransition::QEventTransition(QState *sourceState = nullptr)

Constructs a new QEventTransition object with the given sourceState.

### `[virtual]` QEventTransition::~QEventTransition()

Destroys this QObject event transition.

### `[override virtual protected]` bool QEventTransition::event(QEvent *e)

Reimplements: QAbstractTransition::event(QEvent *e).

### QObject *QEventTransition::eventSource() const

Returns the event source associated with this event transition.

Note: Getter function for property eventSource.

See also setEventSource().

### `[override virtual protected]` bool QEventTransition::eventTest(QEvent *event)

Reimplements: QAbstractTransition::eventTest(QEvent *event).

### QEvent::Type QEventTransition::eventType() const

Returns the event type that this event transition is associated with.

Note: Getter function for property eventType.

See also setEventType().

### `[override virtual protected]` void QEventTransition::onTransition(QEvent *event)

Reimplements: QAbstractTransition::onTransition(QEvent *event).

### void QEventTransition::setEventSource(QObject *object)

Sets the event source associated with this event transition to be the given object.

Note: Setter function for property eventSource.

See also eventSource().

### void QEventTransition::setEventType(QEvent::Type type)

Sets the event type that this event transition is associated with.

Note: Setter function for property eventType.

See also eventType().