Qt 5.9 | Qt Core | C++ Classes | QSignalTransition

Qt 5.9.9 Reference Documentation

# 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

- List of all members, including inherited members

## Properties

- senderObject : QObject *
- signal : QByteArray

- 4 properties inherited from QAbstractTransition
- 1 property inherited from QObject

## Public Functions

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

- 11 public functions inherited from QAbstractTransition
- 32 public functions inherited from QObject

## Signals

void | senderObjectChanged()
void | signalChanged()

- 3 signals inherited from QAbstractTransition
- 2 signals inherited from QObject

## Reimplemented Protected Functions

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

- 3 protected functions inherited from QAbstractTransition
- 9 protected functions inherited from QObject

### Additional Inherited Members

- 1 public slot inherited from QObject
- 11 static public members inherited from QObject
- 3 protected functions inherited from QAbstractTransition
- 9 protected functions inherited from QObject

## Detailed Description

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

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

### QSignalTransition::QSignalTransition(QState *sourceState = Q_NULLPTR)

Constructs a new signal transition with the given sourceState.

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

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

### QSignalTransition::QSignalTransition(const QObject *sender, PointerToMemberFunction signal, QState *sourceState = Q_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()

Destroys this signal transition.

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

Reimplemented from QObject::event().

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

Reimplemented from QAbstractTransition::eventTest().

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.

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

Reimplemented from QAbstractTransition::onTransition().

### QObject *QSignalTransition::senderObject() const

Returns the sender object associated with this signal transition.

Note: Getter function for property senderObject.

See also setSenderObject().

### `[signal]` void QSignalTransition::senderObjectChanged()

This signal is emitted when the senderObject property is changed.

This function was introduced in Qt 5.4.

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.

See also QSignalTransition::senderObject.

### 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().

### `[signal]` void QSignalTransition::signalChanged()

This signal is emitted when the signal property is changed.

This function was introduced in Qt 5.4.

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.

See also QSignalTransition::signal.