QBasicDrag is a base class for implementing platform drag and drop. More...

#include <qsimpledrag_p.h>

Inheritance diagram for QBasicDrag:

Collaboration diagram for QBasicDrag:

Public Member Functions
	~QBasicDrag ()

virtual Qt::DropAction	drag (QDrag *drag) override

void	cancelDrag () override
	Cancels the currently active drag (only for drags of the current application initiated by QPlatformDrag::drag()).

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

Public Member Functions inherited from QPlatformDrag
	QPlatformDrag ()

virtual	~QPlatformDrag ()

QDrag *	currentDrag () const

void	updateAction (Qt::DropAction action)
	Called to notify QDrag about changes of the current action.

virtual Qt::DropAction	defaultAction (Qt::DropActions possibleActions, Qt::KeyboardModifiers modifiers) const

virtual bool	ownsDragObject () const
	Returns bool indicating whether QPlatformDrag takes ownership and therefore responsibility of deleting the QDrag object passed in from QPlatformDrag::drag. This can be useful on platforms where QDrag object has to be kept around.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

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

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

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

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

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

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

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

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

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

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) 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.

template<typename T >
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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

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

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

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

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

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

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

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

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

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

bool	setProperty (const char *name, QVariant &&value)

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

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

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

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`.

Protected Member Functions
	QBasicDrag ()

virtual void	startDrag ()

virtual void	cancel ()

virtual void	move (const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods)=0

virtual void	drop (const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods)=0

virtual void	endDrag ()

void	moveShapedPixmapWindow (const QPoint &deviceIndependentPosition)
	Move the drag label to globalPos, which is interpreted in device independent coordinates.

QShapedPixmapWindow *	shapedPixmapWindow () const

void	recreateShapedPixmapWindow (QScreen *screen, const QPoint &pos)

void	updateCursor (Qt::DropAction action)

bool	canDrop () const

void	setCanDrop (bool c)

bool	useCompositing () const

void	setUseCompositing (bool on)

void	setScreen (QScreen *screen)

Qt::DropAction	executedDropAction () const

void	setExecutedDropAction (Qt::DropAction da)

QDrag *	drag () const

Protected Member Functions inherited from QObject
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 \nullptr.

int	senderSignalIndex () const

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

bool	isSignalConnected (const QMetaMethod &signal) const

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

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

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

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

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

Protected Attributes
QWindow *	m_sourceWindow = nullptr

QPointer< QWindow >	m_windowUnderCursor = nullptr

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

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

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Static Public Member Functions inherited from QPlatformDrag
static QPixmap	defaultPixmap ()

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

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

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

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

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

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

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

QBasicDrag is a base class for implementing platform drag and drop.

Since: 5.0

QBasicDrag implements QPlatformDrag::drag() by running a local event loop in which it tracks mouse movements and moves the drag icon (QShapedPixmapWindow) accordingly. It provides new virtuals allowing for querying whether the receiving window (within the Qt application or outside) accepts the drag and sets the state accordingly.

Definition at line 35 of file qsimpledrag_p.h.

Constructor & Destructor Documentation

◆ ~QBasicDrag()

QBasicDrag::~QBasicDrag ( )

Definition at line 64 of file qsimpledrag.cpp.

◆ QBasicDrag()

QBasicDrag::QBasicDrag ( )

protected

Definition at line 60 of file qsimpledrag.cpp.

Member Function Documentation

◆ cancel()

void QBasicDrag::cancel ( )

protectedvirtual

Reimplemented in QSimpleDrag, and QXcbDrag.

Definition at line 226 of file qsimpledrag.cpp.

References QWindow::setVisible().

Referenced by QSimpleDrag::cancel(), QXcbDrag::cancel(), cancelDrag(), and eventFilter().

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◆ cancelDrag()

void QBasicDrag::cancelDrag ( )

overridevirtual

Cancels the currently active drag (only for drags of the current application initiated by QPlatformDrag::drag()).

The default implementation does nothing.

Since: 5.7

Reimplemented from QPlatformDrag.

Definition at line 185 of file qsimpledrag.cpp.

References cancel(), and QEventLoop::quit().

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◆ canDrop()

bool QBasicDrag::canDrop ( ) const

inlineprotected

Definition at line 60 of file qsimpledrag_p.h.

Referenced by QXcbDrag::endDrag(), eventFilter(), QSimpleDrag::startDrag(), and updateCursor().

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◆ drag() [1/2]

QDrag * QBasicDrag::drag ( ) const

inlineprotected

Definition at line 71 of file qsimpledrag_p.h.

Referenced by QSimpleDrag::cancel(), QWasmDrag::drag(), QSimpleDrag::drop(), QXcbDrag::handleStatus(), QSimpleDrag::move(), and QXcbDrag::startDrag().

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◆ drag() [2/2]

Qt::DropAction QBasicDrag::drag ( QDrag * drag )

overridevirtual

Implements QPlatformDrag.

Reimplemented in QWasmDrag.

Definition at line 168 of file qsimpledrag.cpp.

References endDrag(), QEventLoop::exec(), Qt::IgnoreAction, o, and startDrag().

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◆ drop()

void QBasicDrag::drop	(	const QPoint &	globalPos,
		Qt::MouseButtons	b,
		Qt::KeyboardModifiers	mods )

protectedpure virtual

Implemented in QSimpleDrag, and QXcbDrag.

Definition at line 244 of file qsimpledrag.cpp.

References QWindow::setVisible().

Referenced by QSimpleDrag::drop(), QXcbDrag::drop(), and eventFilter().

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◆ endDrag()

void QBasicDrag::endDrag ( )

protectedvirtual

Reimplemented in QXcbDrag.

Definition at line 208 of file qsimpledrag.cpp.

Referenced by drag(), and QXcbDrag::endDrag().

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◆ eventFilter()

bool QBasicDrag::eventFilter	(	QObject *	watched,
		QEvent *	event )

overridevirtual

Filters events if this object has been installed as an event filter for the watched object.

In your reimplementation of this function, if you want to filter the event out, i.e. stop it being handled further, return true; otherwise return false.

Example:

class MainWindow : public QMainWindow
{
public:
    MainWindow();
 
protected:
    bool eventFilter(QObject *obj, QEvent *ev) override;
 
private:
    QTextEdit *textEdit;
};
 
MainWindow::MainWindow()
{
    textEdit = new QTextEdit;
    setCentralWidget(textEdit);
 
    textEdit->installEventFilter(this);
}
 
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
    if (obj == textEdit) {
        if (event->type() == QEvent::KeyPress) {
            QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
            qDebug() << "Ate key press" << keyEvent->key();
            return true;
        } else {
            return false;
        }
    } else {
        // pass the event on to the parent class
        return QMainWindow::eventFilter(obj, event);
    }
}

Notice in the example above that unhandled events are passed to the base class's eventFilter() function, since the base class might have reimplemented eventFilter() for its own internal purposes.

Some events, such as \l QEvent::ShortcutOverride must be explicitly accepted (by calling \l {QEvent::}{accept()} on them) in order to prevent propagation.

Warning: If you delete the receiver object in this function, be sure to return true. Otherwise, Qt will forward the event to the deleted object and the program might crash.

See also: installEventFilter()

Reimplemented from QObject.

Reimplemented in QXcbDrag.

Definition at line 85 of file qsimpledrag.cpp.

References QEvent::accept(), cancel(), canDrop(), drop(), getNativeMousePos(), QKeyEvent::key(), Qt::Key_Escape, QGuiApplication::keyboardModifiers(), QEvent::KeyPress, QEvent::KeyRelease, m_sourceWindow, QEvent::MouseButtonDblClick, QEvent::MouseButtonRelease, QGuiApplication::mouseButtons(), QEvent::MouseMove, move(), o, QCoreApplication::postEvent(), Q_UNUSED, qCDebug, release(), QEvent::ShortcutOverride, topLevelAt(), QEvent::type(), and QEvent::Wheel.

Referenced by QXcbDrag::eventFilter().

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◆ executedDropAction()

Qt::DropAction QBasicDrag::executedDropAction ( ) const

inlineprotected

Definition at line 68 of file qsimpledrag_p.h.

◆ move()

virtual void QBasicDrag::move	(	const QPoint &	globalPos,
		Qt::MouseButtons	b,
		Qt::KeyboardModifiers	mods )

protectedpure virtual

Implemented in QSimpleDrag, and QXcbDrag.

Referenced by eventFilter().

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◆ moveShapedPixmapWindow()

void QBasicDrag::moveShapedPixmapWindow ( const QPoint & globalPos )

protected

Move the drag label to globalPos, which is interpreted in device independent coordinates.

Typically called from reimplementations of move().

Definition at line 238 of file qsimpledrag.cpp.

References QShapedPixmapWindow::updateGeometry().

Referenced by QSimpleDrag::move(), and QXcbDrag::move().

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◆ recreateShapedPixmapWindow()

void QBasicDrag::recreateShapedPixmapWindow	(	QScreen *	screen,
		const QPoint &	pos )

protected

Definition at line 212 of file qsimpledrag.cpp.

References QDrag::hotSpot(), QDrag::pixmap(), pos, screen, QShapedPixmapWindow::setHotspot(), QShapedPixmapWindow::setPixmap(), QShapedPixmapWindow::setUseCompositing(), QWindow::setVisible(), and QShapedPixmapWindow::updateGeometry().

Referenced by QXcbDrag::move(), and startDrag().

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◆ setCanDrop()

void QBasicDrag::setCanDrop ( bool c )

inlineprotected

Definition at line 61 of file qsimpledrag_p.h.

Referenced by QSimpleDrag::move(), QXcbDrag::move(), and QSimpleDrag::startDrag().

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◆ setExecutedDropAction()

void QBasicDrag::setExecutedDropAction ( Qt::DropAction da )

inlineprotected

Definition at line 69 of file qsimpledrag_p.h.

Referenced by QSimpleDrag::drop(), QXcbDrag::endDrag(), QXcbDrag::handleDrop(), and QSimpleDrag::startDrag().

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◆ setScreen()

void QBasicDrag::setScreen ( QScreen * screen )

inlineprotected

Definition at line 66 of file qsimpledrag_p.h.

References screen.

Referenced by QXcbDrag::startDrag().

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◆ setUseCompositing()

void QBasicDrag::setUseCompositing ( bool on )

inlineprotected

Definition at line 64 of file qsimpledrag_p.h.

Referenced by QXcbDrag::move(), and QXcbDrag::startDrag().

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◆ shapedPixmapWindow()

QShapedPixmapWindow * QBasicDrag::shapedPixmapWindow ( ) const

inlineprotected

Definition at line 56 of file qsimpledrag_p.h.

Referenced by QXcbDrag::eventFilter(), QXcbDrag::findXdndAwareTarget(), QXcbDrag::move(), and QXcbDrag::startDrag().

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◆ startDrag()

void QBasicDrag::startDrag ( )

protectedvirtual

Reimplemented in QSimpleDrag, and QXcbDrag.

Definition at line 193 of file qsimpledrag.cpp.

References pos, QCursor::pos(), qInf(), and recreateShapedPixmapWindow().

Referenced by drag(), QSimpleDrag::startDrag(), and QXcbDrag::startDrag().

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◆ updateCursor()

void QBasicDrag::updateCursor ( Qt::DropAction action )

protected

Definition at line 257 of file qsimpledrag.cpp.

References QPixmap::cacheKey(), canDrop(), QGuiApplication::changeOverrideCursor(), Qt::CopyAction, cursor, Qt::DragCopyCursor, QDrag::dragCursor(), Qt::DragLinkCursor, Qt::DragMoveCursor, Qt::ForbiddenCursor, Qt::LinkAction, QGuiApplication::overrideCursor(), QCursor::pixmap(), pixmap, QGuiApplication::setOverrideCursor(), QCursor::shape(), and QPlatformDrag::updateAction().

Referenced by QSimpleDrag::move(), QXcbDrag::move(), and QSimpleDrag::startDrag().

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◆ useCompositing()

bool QBasicDrag::useCompositing ( ) const

inlineprotected

Definition at line 63 of file qsimpledrag_p.h.

Member Data Documentation

◆ m_sourceWindow

QWindow* QBasicDrag::m_sourceWindow = nullptr

protected

Definition at line 74 of file qsimpledrag_p.h.

Referenced by QSimpleDrag::cancel(), eventFilter(), and QSimpleDrag::startDrag().

◆ m_windowUnderCursor

QPointer<QWindow> QBasicDrag::m_windowUnderCursor = nullptr

protected

Definition at line 75 of file qsimpledrag_p.h.

Referenced by QSimpleDrag::move(), and QSimpleDrag::startDrag().

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

qtbase/src/gui/kernel/qsimpledrag_p.h (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/gui/kernel/qsimpledrag.cpp (3ee289e40d1a7d3582cb1a3a304e681d2085bb82)

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ~QBasicDrag()

◆ QBasicDrag()

Member Function Documentation

◆ cancel()

◆ cancelDrag()

◆ canDrop()

◆ drag() [1/2]

◆ drag() [2/2]

◆ drop()

◆ endDrag()

◆ eventFilter()

◆ executedDropAction()

◆ move()

◆ moveShapedPixmapWindow()

◆ recreateShapedPixmapWindow()

◆ setCanDrop()

◆ setExecutedDropAction()

◆ setScreen()

◆ setUseCompositing()

◆ shapedPixmapWindow()

◆ startDrag()

◆ updateCursor()

◆ useCompositing()

Member Data Documentation

◆ m_sourceWindow

◆ m_windowUnderCursor