The QDrag class provides support for MIME-based drag and drop data transfer. More...

Inheritance diagram for QDrag:

Public Signals
void	actionChanged (Qt::DropAction action)

void	targetChanged (QObject *newTarget)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Methods
	QDrag (QObject *dragSource)

	~QDrag ()

Qt::DropAction	defaultAction () const

QPixmap	dragCursor (Qt::DropAction action) const

Qt::DropAction	exec (Qt::DropActions supportedActions, Qt::DropAction defaultAction)

Qt::DropAction	exec (Qt::DropActions supportedActions=Qt::MoveAction)

QPoint	hotSpot () const

QMimeData *	mimeData () const

QPixmap	pixmap () const

void	setDragCursor (const QPixmap &cursor, Qt::DropAction action)

void	setHotSpot (const QPoint &hotspot)

void	setMimeData (QMimeData *data)

void	setPixmap (const QPixmap &pixmap)

QObject *	source () const

Qt::DropAction	start (Qt::DropActions supportedActions=Qt::CopyAction)

Qt::DropActions	supportedActions () const

QObject *	target () const

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()

Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Properties inherited from QObject
	objectName

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QDrag class provides support for MIME-based drag and drop data transfer.

Drag and drop is an intuitive way for users to copy or move data around in an application, and is used in many desktop environments as a mechanism for copying data between applications. Drag and drop support in CopperSpice is centered around the QDrag class that handles most of the details of a drag and drop operation.

The data to be transferred by the drag and drop operation is contained in a QMimeData object. This is specified with the setMimeData() function in the following way:

QDrag *drag = new QDrag(this);
QMimeData *mimeData = new QMimeData;
 
mimeData->setText(commentEdit->toPlainText());
drag->setMimeData(mimeData);

Calling setMimeData() will assign ownership of the QMimeData object to the QDrag object. The QDrag must be constructed on the heap with a parent QWidget to ensure that CopperSpice can clean up after the drag and drop operation has been completed.

A pixmap can be used to represent the data while the drag is in progress, and will move with the cursor to the drop target. This pixmap typically shows an icon that represents the MIME type of the data being transferred, but any pixmap can be set with setPixmap(). The cursor's hot spot can be given a position relative to the top-left corner of the pixmap with the setHotSpot() function. The following code positions the pixmap so that the cursor's hot spot points to the center of its bottom edge:

drag->setHotSpot(QPoint(drag->pixmap().width()/2, drag->pixmap().height()));

On X11, the pixmap may not be able to keep up with the mouse movements if the hot spot causes the pixmap to be displayed directly under the cursor.

The source and target widgets can be found with source() and target(). These functions are often used to determine whether drag and drop operations started and finished at the same widget, so that special behavior can be implemented.

QDrag only deals with the drag and drop operation itself. It is up to the developer to decide when a drag operation begins, and how a QDrag object should be constructed and used. For a given widget, it is often necessary to reimplement mousePressEvent() to determine whether the user has pressed a mouse button, and reimplement mouseMoveEvent() to check whether a QDrag is required.

See also: QClipboard, QMimeData, Drag and Drop,

Constructor & Destructor Documentation

QDrag::QDrag ( QObject * dragSource )

explicit

Constructs a new drag object for the widget specified by dragSource.

QDrag::~QDrag ( )

Destroys the drag object.

Method Documentation

void QDrag::actionChanged ( Qt::DropAction action )

signal

This signal is emitted when the action associated with the drag changes.

See also: targetChanged()

Qt::DropAction QDrag::defaultAction ( ) const

Returns the default proposed drop action for this drag operation.

See also: exec(), supportedActions()

QPixmap QDrag::dragCursor ( Qt::DropAction action ) const

Returns the drag cursor for the action.

Qt::DropAction QDrag::exec	(	Qt::DropActions	supportedActions,
		Qt::DropAction	defaultAction
	)

Starts the drag and drop operation and returns a value indicating the requested drop action when it is completed. The drop actions that the user can choose from are specified in supportedActions. The defaultAction determines which action will be proposed when the user performs a drag without using modifier keys.

Note: On Linux and Mac OS X, the drag and drop operation can take some time, but this function does not block the event loop. Other events are still delivered to the application while the operation is performed. On Windows, the CopperSpice event loop is blocked during the operation. However, QDrag::exec() on Windows causes processEvents() to be called frequently to keep the GUI responsive. If any loops or operations are called while a drag operation is active, it will block the drag operation.

Qt::DropAction QDrag::exec ( Qt::DropActions supportedActions = Qt::MoveAction )

Starts the drag and drop operation and returns a value indicating the requested drop action when it is completed. The drop actions that the user can choose from are specified in supportedActions. The default proposed action will be selected among the allowed actions in the following order: Move, Copy and Link.

Note: On Linux and Mac OS X, the drag and drop operation can take some time, but this function does not block the event loop. Other events are still delivered to the application while the operation is performed. On Windows, the CopperSpice event loop is blocked while during the operation.

QPoint QDrag::hotSpot ( ) const

Returns the position of the hot spot relative to the top-left corner of the cursor.

See also: setHotSpot()

QMimeData * QDrag::mimeData ( ) const

Returns the MIME data that is encapsulated by the drag object.

See also: setMimeData()

QPixmap QDrag::pixmap ( ) const

Returns the pixmap used to represent the data in a drag and drop operation.

See also: setPixmap()

void QDrag::setDragCursor	(	const QPixmap &	cursor,
		Qt::DropAction	action
	)

Sets the drag cursor for the action. This allows you to override the default native cursors. To revert to using the native cursor for action pass in a null QPixmap as cursor.

The action can only be CopyAction, MoveAction or LinkAction. All other values of DropAction are ignored.

void QDrag::setHotSpot ( const QPoint & hotspot )

Sets the position of the hot spot relative to the top-left corner of the pixmap used to the point specified by hotspot.

Note: on X11, the pixmap may not be able to keep up with the mouse movements if the hot spot causes the pixmap to be displayed directly under the cursor.

See also: hotSpot()

void QDrag::setMimeData ( QMimeData * data )

Sets the data to be sent to the given MIME data. Ownership of the data is transferred to the QDrag object.

See also: mimeData()

void QDrag::setPixmap ( const QPixmap & pixmap )

Sets pixmap as the pixmap used to represent the data in a drag and drop operation. You can only set a pixmap before the drag is started.

See also: pixmap()

QObject * QDrag::source ( ) const

Returns the source of the drag object. This is the widget where the drag and drop operation originated.

Qt::DropAction QDrag::start ( Qt::DropActions supportedActions = Qt::CopyAction )

deprecated

Deprecated:

Note: It is recommended to use exec() instead of this method.

Starts the drag and drop operation and returns a value indicating the requested drop action when it is completed. The drop actions that the user can choose from are specified in supportedActions. Qt::CopyAction is always allowed.

Note: Although the drag and drop operation can take some time, this function does not block the event loop. Other events are still delivered to the application while the operation is performed.

See also: exec()

Qt::DropActions QDrag::supportedActions ( ) const

Returns the set of possible drop actions for this drag operation.

See also: exec(), defaultAction()

QObject * QDrag::target ( ) const

Returns the target of the drag and drop operation. This is the widget where the drag object was dropped.

void QDrag::targetChanged ( QObject * newTarget )

signal

This signal is emitted when the target of the drag and drop operation changes, with newTarget the new target.

See also: target(), actionChanged()

Public Signals

Public Methods

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Method Documentation