QSignalTransition Class

The QSignalTransition class provides a transition based on a Qt signal. More...

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

This class was introduced in Qt 4.6.

Properties

Public Functions

QSignalTransition(const QObject *sender, PointerToMemberFunction signal, QState *sourceState = nullptr)
QSignalTransition(const QObject *sender, const char *signal, QState *sourceState = nullptr)
QSignalTransition(QState *sourceState = nullptr)
virtual ~QSignalTransition()
QObject *senderObject() const
void setSenderObject(const QObject *sender)
void setSignal(const QByteArray &signal)
QByteArray signal() const

Signals

Reimplemented Protected Functions

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

Detailed Description

Typically you would use the overload of QState::addTransition() that takes a sender and signal as arguments, rather than creating QSignalTransition objects directly. QSignalTransition is part of The State Machine Framework.

You can subclass QSignalTransition and reimplement eventTest() to make a signal transition conditional; the event object passed to eventTest() will be a QStateMachine::SignalEvent object. Example:

class CheckedTransition : public QSignalTransition
{
public:
    CheckedTransition(QCheckBox *check)
        : QSignalTransition(check, SIGNAL(stateChanged(int))) {}
protected:
    bool eventTest(QEvent *e) {
        if (!QSignalTransition::eventTest(e))
            return false;
        QStateMachine::SignalEvent *se = static_cast<QStateMachine::SignalEvent*>(e);
        return (se->arguments().at(0).toInt() == Qt::Checked);
    }
};

...

QCheckBox *check = new QCheckBox();
check->setTristate(true);

QState *s1 = new QState();
QState *s2 = new QState();
CheckedTransition *t1 = new CheckedTransition(check);
t1->setTargetState(s2);
s1->addTransition(t1);

Property Documentation

senderObject : QObject*

This property holds the sender object that this signal transition is associated with

Access functions:

QObject *senderObject() const
void setSenderObject(const QObject *sender)

Notifier signal:

void senderObjectChanged()[see note below]

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

signal : QByteArray

This property holds the signal that this signal transition is associated with

Access functions:

QByteArray signal() const
void setSignal(const QByteArray &signal)

Notifier signal:

void signalChanged()[see note below]

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

Member Function Documentation

template <typename PointerToMemberFunction> QSignalTransition::QSignalTransition(const QObject *sender, PointerToMemberFunction signal, QState *sourceState = nullptr)

This is an overloaded function.

Constructs a new signal transition associated with the given signal of the given sender object and with the given sourceState. This constructor is enabled if the compiler supports delegating constructors, as indicated by the presence of the macro Q_COMPILER_DELEGATING_CONSTRUCTORS.

This function was introduced in Qt 5.7.

QSignalTransition::QSignalTransition(const QObject *sender, const char *signal, QState *sourceState = nullptr)

Constructs a new signal transition associated with the given signal of the given sender, and with the given sourceState.

QSignalTransition::QSignalTransition(QState *sourceState = nullptr)

Constructs a new signal transition with the given sourceState.

[signal] void QSignalTransition::senderObjectChanged()

This signal is emitted when the senderObject property is changed.

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

Note: Notifier signal for property senderObject.

This function was introduced in Qt 5.4.

See also QSignalTransition::senderObject.

[signal] void QSignalTransition::signalChanged()

This signal is emitted when the signal property is changed.

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

Note: Notifier signal for property signal.

This function was introduced in Qt 5.4.

See also QSignalTransition::signal.

[virtual] QSignalTransition::~QSignalTransition()

Destroys this signal transition.

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

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

[override virtual protected] bool QSignalTransition::eventTest(QEvent *event)

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

The default implementation returns true if the event is a QStateMachine::SignalEvent object and the event's sender and signal index match this transition, and returns false otherwise.

[override virtual protected] void QSignalTransition::onTransition(QEvent *event)

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

QObject *QSignalTransition::senderObject() const

Returns the sender object associated with this signal transition.

Note: Getter function for property senderObject.

See also setSenderObject().

void QSignalTransition::setSenderObject(const QObject *sender)

Sets the sender object associated with this signal transition.

Note: Setter function for property senderObject.

See also senderObject().

void QSignalTransition::setSignal(const QByteArray &signal)

Sets the signal associated with this signal transition.

Note: Setter function for property signal.

See also signal().

QByteArray QSignalTransition::signal() const

Returns the signal associated with this signal transition.

Note: Getter function for property signal.

See also setSignal().

© 2020 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.