QSignalTransition Class

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

Header:	#include <QSignalTransition>
CMake:	find_package(Qt6 COMPONENTS StateMachine REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::StateMachine)
qmake:	QT += statemachine
Inherits:	QAbstractTransition

• List of all members, including inherited members

Properties

• senderObject : const QObject*
• signal : QByteArray

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()
const QObject *	senderObject() const
void	setSenderObject(const QObject *sender)
void	setSignal(const QByteArray &signal)
QByteArray	signal() const

Signals

void	senderObjectChanged()
void	signalChanged()

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 Qt 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);

Member Function Documentation

[since 5.7] 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.

[private signal, since 5.4] 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.

[private signal, since 5.4] 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).

const 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().