The QHistoryState class provides a means of returning to a previously active substate. More...

#include <qhistorystate.h>

Inheritance diagram for QHistoryState:

Public Types
enum	HistoryType { ShallowHistory, DeepHistory }
	This enum specifies the type of history that a QHistoryState records. More...

Public Functions
QAbstractState *	defaultState () const

HistoryType	historyType () const

	QHistoryState (QState *parent=0)
	Constructs a new shallow history state with the given parent state. More...

	QHistoryState (HistoryType type, QState *parent=0)
	Constructs a new history state of the given type, with the given parent state. More...

void	setDefaultState (QAbstractState *state)
	Sets this history state's default state to be the given state. More...

void	setHistoryType (HistoryType type)
	Sets the type of history that this history state records. More...

	~QHistoryState ()
	Destroys this history state. More...

Public Functions inherited from QAbstractState
QStateMachine *	machine () const
	Returns the state machine that this state is part of, or 0 if the state is not part of a state machine. More...

QState *	parentState () const
	Returns this state's parent state, or 0 if the state has no parent state. More...

	~QAbstractState ()
	Destroys this state. More...

Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...

const QObjectList &	children () const
	Returns a list of child objects. More...

bool	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=0, const QObject receiver=0, const char *member=0)

bool	disconnect (const QObject receiver, const char member=0)

void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...

void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...

QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...

virtual bool	eventFilter (QObject , QEvent )
	Filters events if this object has been installed as an event filter for the watched object. More...

template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...

template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...

template<typename T >
QList< T >	findChildren (const QRegExp &re) const

bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...

void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...

bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...

void	killTimer (int id)
	Kills the timer with timer identifier, id. More...

virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...

QString	objectName () const

QObject *	parent () const
	Returns a pointer to the parent object. More...

QVariant	property (const char *name) const
	Returns the value of the object's name property. More...

Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...

void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...

void	setObjectName (const QString &name)

void	setParent (QObject *)
	Makes the object a child of parent. More...

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...

void	setUserData (uint id, QObjectUserData *data)

bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...

int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...

QThread *	thread () const
	Returns the thread in which the object lives. More...

QObjectUserData *	userData (uint id) const

virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Protected Functions
bool	event (QEvent *e)
	Reimplemented Function More...

void	onEntry (QEvent *event)
	Reimplemented Function More...

void	onExit (QEvent *event)
	Reimplemented Function More...

Protected Functions inherited from QAbstractState
	QAbstractState (QState *parent=0)
	Constructs a new state with the given parent state. More...

	QAbstractState (QAbstractStatePrivate &dd, QState *parent)

Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...

virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...

virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...

virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...

	QObject (QObjectPrivate &dd, QObject *parent=0)

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...

QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...

Properties
QAbstractState *	defaultState
	the default state of this history state More...

HistoryType	historyType
	the type of history that this history state records More...

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

Signals inherited from QAbstractState
void	entered ()
	This signal is emitted when the state has been entered (after onEntry() has been called). More...

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

Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...

Static Public Functions inherited from QObject
static bool	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...

static bool	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	Disconnects signal in object sender from method in object receiver. More...

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static uint	registerUserData ()

static QString	tr (const char sourceText, const char comment=0, int n=-1)

static QString	trUtf8 (const char sourceText, const char comment=0, int n=-1)

Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...

Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject

Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()

T *	qobject_cast (QObject *object)

	QObjectList

void *	qt_find_obj_child (QObject parent, const char type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QHistoryState class provides a means of returning to a previously active substate.

Since: 4.6

A history state is a pseudo-state that represents the child state that the parent state was in the last time the parent state was exited. A transition with a history state as its target is in fact a transition to one of the other child states of the parent state. QHistoryState is part of The State Machine Framework.

Use the setDefaultState() function to set the state that should be entered if the parent state has never been entered. Example:

QStateMachine machine;
QState *s1 = new QState();
QState *s11 = new QState(s1);
QState *s12 = new QState(s1);
QHistoryState *s1h = new QHistoryState(s1);
s1h->setDefaultState(s11);
machine.addState(s1);
QState *s2 = new QState();
machine.addState(s2);
QPushButton *button = new QPushButton();
// Clicking the button will cause the state machine to enter the child state
// that s1 was in the last time s1 was exited, or the history state's default
// state if s1 has never been entered.
s1->addTransition(button, SIGNAL(clicked()), s1h);

By default a history state is shallow, meaning that it won't remember nested states. This can be configured through the historyType property.

Definition at line 56 of file qhistorystate.h.

Enumerations

◆ HistoryType

enum QHistoryState::HistoryType

This enum specifies the type of history that a QHistoryState records.

ShallowHistory Only the immediate child states of the parent state are recorded. In this case a transition with the history state as its target will end up in the immediate child state that the parent was in the last time it was exited. This is the default.

DeepHistory Nested states are recorded. In this case a transition with the history state as its target will end up in the most deeply nested descendant state the parent was in the last time it was exited.

Enumerator
ShallowHistory
DeepHistory

Definition at line 63 of file qhistorystate.h.

                      {
         ShallowHistory,
         DeepHistory
     };

Constructors and Destructors

◆ QHistoryState() [1/2]

QHistoryState::QHistoryState ( QState * parent = 0 )

Constructs a new shallow history state with the given parent state.

Definition at line 148 of file qhistorystate.cpp.

     : QAbstractState(*new QHistoryStatePrivate, parent)
 {
 }

◆ QHistoryState() [2/2]

QHistoryState::QHistoryState	(	HistoryType	type,
		QState *	parent = `0`
	)

Constructs a new history state of the given type, with the given parent state.

Definition at line 156 of file qhistorystate.cpp.

     : QAbstractState(*new QHistoryStatePrivate, parent)
 {
     Q_D(QHistoryState);
     d->historyType = type;
 }

◆ ~QHistoryState()

QHistoryState::~QHistoryState ( )

Destroys this history state.

Definition at line 166 of file qhistorystate.cpp.

167 {

168 }

Functions

◆ defaultState()

QAbstractState* QHistoryState::defaultState ( ) const

Referenced by ~QHistoryState().

◆ event()

bool QHistoryState::event ( QEvent * e )

protectedvirtual

Reimplemented Function

Reimplemented from QAbstractState.

Definition at line 235 of file qhistorystate.cpp.

 {
     return QAbstractState::event(e);
 }

◆ historyType()

HistoryType QHistoryState::historyType ( ) const

Referenced by setDefaultState().

◆ onEntry()

void QHistoryState::onEntry ( QEvent * event )

protectedvirtual

Reimplemented Function

Implements QAbstractState.

Definition at line 219 of file qhistorystate.cpp.

 {
     Q_UNUSED(event);
 }

◆ onExit()

void QHistoryState::onExit ( QEvent * event )

protectedvirtual

Reimplemented Function

Implements QAbstractState.

Definition at line 227 of file qhistorystate.cpp.

 {
     Q_UNUSED(event);
 }

◆ setDefaultState()

void QHistoryState::setDefaultState ( QAbstractState * state )

Sets this history state's default state to be the given state.

state must be a sibling of this history state.

Note that this function does not set state as the initial state of its parent.

Definition at line 187 of file qhistorystate.cpp.

 {
     Q_D(QHistoryState);
     if (state && state->parentState() != parentState()) {
         qWarning("QHistoryState::setDefaultState: state %p does not belong "
                  "to this history state's group (%p)", state, parentState());
         return;
     }
     d->defaultState = state;
 }

◆ setHistoryType()

void QHistoryState::setHistoryType ( HistoryType type )

Sets the type of history that this history state records.

Definition at line 210 of file qhistorystate.cpp.

 {
     Q_D(QHistoryState);
     d->historyType = type;
 }

Properties

◆ defaultState

QAbstractState * QHistoryState::defaultState

private

the default state of this history state

Returns this history state's default state.

The default state indicates the state to transition to if the parent state has never been entered before.

Definition at line 59 of file qhistorystate.h.

◆ historyType

QHistoryState::HistoryType QHistoryState::historyType

private

the type of history that this history state records

Returns the type of history that this history state records.

The default value of this property is QHistoryState::ShallowHistory.

Definition at line 60 of file qhistorystate.h.

The documentation for this class was generated from the following files:

/src/corelib/statemachine/qhistorystate.h
/src/corelib/statemachine/qhistorystate.cpp

Public Types

Public Functions

Protected Functions

Properties

Additional Inherited Members

Detailed Description

Enumerations

◆ HistoryType

Constructors and Destructors

◆ QHistoryState() [1/2]

◆ QHistoryState() [2/2]

◆ ~QHistoryState()

Functions

◆ defaultState()

◆ event()

◆ historyType()

◆ onEntry()

◆ onExit()

◆ setDefaultState()

◆ setHistoryType()

Properties

◆ defaultState

◆ historyType