QSignalMapper Class Reference

The QSignalMapper class bundles signals from identifiable senders. More...

#include <qsignalmapper.h>

Inheritance diagram for QSignalMapper:

Public Slots
void	map ()
	This slot emits signals based on which object sends signals to it. More...
void	map (QObject *sender)
	This slot emits signals based on the sender object. More...
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

Signals
void	mapped (int)
	This signal is emitted when map() is signalled from an object that has an integer mapping set. More...
void	mapped (const QString &)
	This signal is emitted when map() is signalled from an object that has a string mapping set. More...
void	mapped (QWidget *)
	This signal is emitted when map() is signalled from an object that has a widget mapping set. More...
void	mapped (QObject *)
	This signal is emitted when map() is signalled from an object that has an object mapping set. 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...

Public Functions
QObject *	mapping (int id) const
	Returns the sender QObject that is associated with the id. More...
QObject *	mapping (const QString &text) const
QObject *	mapping (QWidget *widget) const
QObject *	mapping (QObject *object) const
	QSignalMapper (QObject *parent=0)
	Constructs a QSignalMapper with parent parent. More...
void	removeMappings (QObject *sender)
	Removes all mappings for sender. More...
void	setMapping (QObject *sender, int id)
	Adds a mapping so that when map() is signalled from the given sender, the signal mapped(id) is emitted. More...
void	setMapping (QObject *sender, const QString &text)
	Adds a mapping so that when map() is signalled from the sender, the signal mapped(text ) is emitted. More...
void	setMapping (QObject *sender, QWidget *widget)
	Adds a mapping so that when map() is signalled from the sender, the signal mapped(widget ) is emitted. More...
void	setMapping (QObject *sender, QObject *object)
	Adds a mapping so that when map() is signalled from the sender, the signal mapped(object ) is emitted. More...
	~QSignalMapper ()
	Destroys the QSignalMapper. 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	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. 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...

Additional Inherited Members
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 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...
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 QSignalMapper class bundles signals from identifiable senders.

This class collects a set of parameterless signals, and re-emits them with integer, string or widget parameters corresponding to the object that sent the signal.

The class supports the mapping of particular strings or integers with particular objects using setMapping(). The objects' signals can then be connected to the map() slot which will emit the mapped() signal with the string or integer associated with the original signalling object. Mappings can be removed later using removeMappings().

Example: Suppose we want to create a custom widget that contains a group of buttons (like a tool palette). One approach is to connect each button's clicked() signal to its own custom slot; but in this example we want to connect all the buttons to a single slot and parameterize the slot by the button that was clicked.

Here's the definition of a simple custom widget that has a single signal, clicked(), which is emitted with the text of the button that was clicked:

class ButtonWidget : public QWidget
{
    Q_OBJECT

public:
    ButtonWidget(QStringList texts, QWidget *parent = 0);

signals:
    void clicked(const QString &text);

private:
    QSignalMapper *signalMapper;

};

The only function that we need to implement is the constructor:

ButtonWidget::ButtonWidget(QStringList texts, QWidget *parent)
    : QWidget(parent)
{
    signalMapper = new QSignalMapper(this);

    QGridLayout *gridLayout = new QGridLayout;
    for (int i = 0; i < texts.size(); ++i) {
    QPushButton *button = new QPushButton(texts[i]);
    connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));

    signalMapper->setMapping(button, texts[i]);
    gridLayout->addWidget(button, i / 3, i % 3);
    }

    connect(signalMapper, SIGNAL(mapped(const QString &)),

            this, SIGNAL(clicked(const QString &)));

    setLayout(gridLayout);
}

A list of texts is passed to the constructor. A signal mapper is constructed and for each text in the list a QPushButton is created. We connect each button's clicked() signal to the signal mapper's map() slot, and create a mapping in the signal mapper from each button to the button's text. Finally we connect the signal mapper's mapped() signal to the custom widget's clicked() signal. When the user clicks a button, the custom widget will emit a single clicked() signal whose argument is the text of the button the user clicked.

See also

QObject, QButtonGroup, QActionGroup

Definition at line 56 of file qsignalmapper.h.

Constructors and Destructors

QSignalMapper()

QSignalMapper::QSignalMapper ( QObject *  parent = 0 )

explicit

Constructs a QSignalMapper with parent parent.

Definition at line 122 of file qsignalmapper.cpp.

    : QObject(*new QSignalMapperPrivate, parent)
{
}

~QSignalMapper()

QSignalMapper::~QSignalMapper

(

)

Destroys the QSignalMapper.

Definition at line 142 of file qsignalmapper.cpp.

{
}

Functions

map [1/2]

void QSignalMapper::map ( )

slot

This slot emits signals based on which object sends signals to it.

Definition at line 266 of file qsignalmapper.cpp.

{ map(sender()); }

map [2/2]

void QSignalMapper::map ( QObject *  sender )

slot

This slot emits signals based on the sender object.

Definition at line 271 of file qsignalmapper.cpp.

{
    Q_D(QSignalMapper);
    if (d->intHash.contains(sender))
        emit mapped(d->intHash.value(sender));
    if (d->stringHash.contains(sender))
        emit mapped(d->stringHash.value(sender));
    if (d->widgetHash.contains(sender))
        emit mapped(d->widgetHash.value(sender));
    if (d->objectHash.contains(sender))
        emit mapped(d->objectHash.value(sender));
}

mapped [1/4]

void QSignalMapper::mapped ( int  i )

signal

This signal is emitted when map() is signalled from an object that has an integer mapping set.

The object's mapped integer is passed in i.

See also

setMapping()

Referenced by map().

mapped [2/4]

void QSignalMapper::mapped ( const QString &  text )

signal

This signal is emitted when map() is signalled from an object that has a string mapping set.

The object's mapped string is passed in text.

See also

setMapping()

mapped [3/4]

void QSignalMapper::mapped ( QWidget *  widget )

signal

This signal is emitted when map() is signalled from an object that has a widget mapping set.

The object's mapped widget is passed in widget.

See also

setMapping()

mapped [4/4]

void QSignalMapper::mapped ( QObject *  object )

signal

This signal is emitted when map() is signalled from an object that has an object mapping set.

The object provided by the map is passed in object.

See also

setMapping()

mapping() [1/4]

QObject * QSignalMapper::mapping

(

int

id

)

const

Returns the sender QObject that is associated with the id.

See also

setMapping()

Definition at line 205 of file qsignalmapper.cpp.

{
    Q_D(const QSignalMapper);
    return d->intHash.key(id);
}

mapping() [2/4]

QObject * QSignalMapper::mapping

(

const QString &

text

)

const

Definition at line 214 of file qsignalmapper.cpp.

{
    Q_D(const QSignalMapper);
    return d->stringHash.key(id);
}

mapping() [3/4]

QObject * QSignalMapper::mapping

(

QWidget *

widget

)

const

Definition at line 228 of file qsignalmapper.cpp.

{
    Q_D(const QSignalMapper);
    return d->widgetHash.key(widget);
}

mapping() [4/4]

QObject * QSignalMapper::mapping

(

QObject *

object

)

const

Definition at line 242 of file qsignalmapper.cpp.

{
    Q_D(const QSignalMapper);
    return d->objectHash.key(object);
}

removeMappings()

void QSignalMapper::removeMappings

(

QObject *

sender

)

Removes all mappings for sender.

This is done automatically when mapped objects are destroyed.

Definition at line 253 of file qsignalmapper.cpp.

{
    Q_D(QSignalMapper);

    d->intHash.remove(sender);
    d->stringHash.remove(sender);
    d->widgetHash.remove(sender);
    d->objectHash.remove(sender);
}

setMapping() [1/4]

void QSignalMapper::setMapping	(	QObject *	sender,
		int	id
	)

Adds a mapping so that when map() is signalled from the given sender, the signal mapped(id) is emitted.

There may be at most one integer ID for each sender.

See also

mapping()

Definition at line 154 of file qsignalmapper.cpp.

Referenced by ShaderEffectItem::connectPropertySignals().

{
    Q_D(QSignalMapper);
    d->intHash.insert(sender, id);
    connect(sender, SIGNAL(destroyed()), this, SLOT(_q_senderDestroyed()));
}

setMapping() [2/4]

void QSignalMapper::setMapping	(	QObject *	sender,
		const QString &	text
	)

Adds a mapping so that when map() is signalled from the sender, the signal mapped(text ) is emitted.

There may be at most one text for each sender.

Definition at line 167 of file qsignalmapper.cpp.

{
    Q_D(QSignalMapper);
    d->stringHash.insert(sender, text);
    connect(sender, SIGNAL(destroyed()), this, SLOT(_q_senderDestroyed()));
}

setMapping() [3/4]

void QSignalMapper::setMapping	(	QObject *	sender,
		QWidget *	widget
	)

Adds a mapping so that when map() is signalled from the sender, the signal mapped(widget ) is emitted.

There may be at most one widget for each sender.

Definition at line 180 of file qsignalmapper.cpp.

{
    Q_D(QSignalMapper);
    d->widgetHash.insert(sender, widget);
    connect(sender, SIGNAL(destroyed()), this, SLOT(_q_senderDestroyed()));
}

setMapping() [4/4]

void QSignalMapper::setMapping	(	QObject *	sender,
		QObject *	object
	)

Adds a mapping so that when map() is signalled from the sender, the signal mapped(object ) is emitted.

There may be at most one object for each sender.

Definition at line 193 of file qsignalmapper.cpp.

{
    Q_D(QSignalMapper);
    d->objectHash.insert(sender, object);
    connect(sender, SIGNAL(destroyed()), this, SLOT(_q_senderDestroyed()));
}

---

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

• /src/corelib/kernel/qsignalmapper.h
• /src/corelib/kernel/qsignalmapper.cpp