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QAbstractState Class

The QAbstractState class is the base class of states of a QStateMachine. More...

Header: #include <QAbstractState>
qmake: QT += core
Since: Qt 4.6
Inherits: QObject
Inherited By:

QFinalState, QHistoryState, and QState

This class was introduced in Qt 4.6.

Properties

Public Functions

virtual ~QAbstractState()
bool active() const
QStateMachine * machine() const
QState * parentState() const

Signals

void activeChanged(bool active)
void entered()
void exited()

Protected Functions

QAbstractState(QState *parent = nullptr)
virtual void onEntry(QEvent *event) = 0
virtual void onExit(QEvent *event) = 0

Reimplemented Protected Functions

virtual bool event(QEvent *e) override

Detailed Description

The QAbstractState class is the abstract base class of states that are part of a QStateMachine. It defines the interface that all state objects have in common. QAbstractState is part of The State Machine Framework.

The entered() signal is emitted when the state has been entered. The exited() signal is emitted when the state has been exited.

The parentState() function returns the state's parent state. The machine() function returns the state machine that the state is part of.

Subclassing

The onEntry() function is called when the state is entered; reimplement this function to perform custom processing when the state is entered.

The onExit() function is called when the state is exited; reimplement this function to perform custom processing when the state is exited.

Property Documentation

active : const bool

This property holds the active property of this state. A state is active between entered() and exited() signals.

This property was introduced in Qt 5.4.

Access functions:

bool active() const

Notifier signal:

void activeChanged(bool active)

Member Function Documentation

[protected] QAbstractState::QAbstractState(QState *parent = nullptr)

Constructs a new state with the given parent state.

[signal] void QAbstractState::activeChanged(bool active)

This signal is emitted when the active property is changed with active as argument.

This function was introduced in Qt 5.4.

Note: Notifier signal for property active.

See also QAbstractState::active, entered(), and exited().

[signal] void QAbstractState::entered()

This signal is emitted when the state has been entered (after onEntry() has been called).

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

[signal] void QAbstractState::exited()

This signal is emitted when the state has been exited (after onExit() has been called).

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

[virtual] QAbstractState::~QAbstractState()

Destroys this state.

bool QAbstractState::active() const

Returns whether this state is active.

Note: Getter function for property active.

See also activeChanged(bool), entered(), and exited().

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

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

QStateMachine *QAbstractState::machine() const

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

[pure virtual protected] void QAbstractState::onEntry(QEvent *event)

This function is called when the state is entered. The given event is what caused the state to be entered. Reimplement this function to perform custom processing when the state is entered.

[pure virtual protected] void QAbstractState::onExit(QEvent *event)

This function is called when the state is exited. The given event is what caused the state to be exited. Reimplement this function to perform custom processing when the state is exited.

QState *QAbstractState::parentState() const

Returns this state's parent state, or nullptr if the state has no parent state.

© The Qt Company Ltd
Licensed under the GNU Free Documentation License, Version 1.3.
https://doc.qt.io/qt-5.13/qabstractstate.html