QAbstractTransition Class

The QAbstractTransition class is the base class of transitions between QAbstractState objects. More...

Header: #include <QAbstractTransition>
Since: Qt 4.6
Inherits: QObject
Inherited By:

QEventTransition and QSignalTransition


  • 1 property inherited from QObject

Public Functions

QAbstractTransition(QState * sourceState = 0)
virtual ~QAbstractTransition()
void addAnimation(QAbstractAnimation * animation)
QList<QAbstractAnimation *> animations() const
QStateMachine * machine() const
void removeAnimation(QAbstractAnimation * animation)
void setTargetState(QAbstractState * target)
void setTargetStates(const QList<QAbstractState *> & targets)
QState * sourceState() const
QAbstractState * targetState() const
QList<QAbstractState *> targetStates() const
  • 29 public functions inherited from QObject


void triggered()

Protected Functions

virtual bool eventTest(QEvent * event) = 0
virtual void onTransition(QEvent * event) = 0

Reimplemented Protected Functions

virtual bool event(QEvent * e)
  • 8 protected functions inherited from QObject

Additional Inherited Members

  • 1 public slot inherited from QObject
  • 7 static public members inherited from QObject

Detailed Description

The QAbstractTransition class is the base class of transitions between QAbstractState objects.

The QAbstractTransition class is the abstract base class of transitions between states (QAbstractState objects) of a QStateMachine. QAbstractTransition is part of The State Machine Framework.

The sourceState() function returns the source of the transition. The targetStates() function returns the targets of the transition. The machine() function returns the state machine that the transition is part of.

The triggered() signal is emitted when the transition has been triggered.

Transitions can cause animations to be played. Use the addAnimation() function to add an animation to the transition.


The eventTest() function is called by the state machine to determine whether an event should trigger the transition. In your reimplementation you typically check the event type and cast the event object to the proper type, and check that one or more properties of the event meet your criteria.

The onTransition() function is called when the transition is triggered; reimplement this function to perform custom processing for the transition.

Property Documentation

sourceState : QState * const

This property holds the source state (parent) of this transition.

Access functions:

QState * sourceState() const

targetState : QAbstractState *

This property holds the target state of this transition.

If a transition has no target state, the transition may still be triggered, but this will not cause the state machine's configuration to change (i.e. the current state will not be exited and re-entered).

Access functions:

QAbstractState * targetState() const
void setTargetState(QAbstractState * target)

targetStates : QList<QAbstractState *>

This property holds the target states of this transition.

If multiple states are specified, all must be descendants of the same parallel group state.

Access functions:

QList<QAbstractState *> targetStates() const
void setTargetStates(const QList<QAbstractState *> & targets)

Member Function Documentation

QAbstractTransition::QAbstractTransition(QState * sourceState = 0)

Constructs a new QAbstractTransition object with the given sourceState.

[virtual] QAbstractTransition::~QAbstractTransition()

Destroys this transition.

void QAbstractTransition::addAnimation(QAbstractAnimation * animation)

Adds the given animation to this transition. The transition does not take ownership of the animation.

See also removeAnimation() and animations().

QList<QAbstractAnimation *> QAbstractTransition::animations() const

Returns the list of animations associated with this transition, or an empty list if it has no animations.

See also addAnimation().

[virtual protected] bool QAbstractTransition::event(QEvent * e)

Reimplemented from QObject::event().

[pure virtual protected] bool QAbstractTransition::eventTest(QEvent * event)

This function is called to determine whether the given event should cause this transition to trigger. Reimplement this function and return true if the event should trigger the transition, otherwise return false.

QStateMachine * QAbstractTransition::machine() const

Returns the state machine that this transition is part of, or 0 if the transition is not part of a state machine.

[pure virtual protected] void QAbstractTransition::onTransition(QEvent * event)

This function is called when the transition is triggered. The given event is what caused the transition to trigger. Reimplement this function to perform custom processing when the transition is triggered.

void QAbstractTransition::removeAnimation(QAbstractAnimation * animation)

Removes the given animation from this transition.

See also addAnimation().

[signal] void QAbstractTransition::triggered()

This signal is emitted when the transition has been triggered (after onTransition() has been called).

© 2016 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.