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Qt
Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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Qt
Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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\inmodule QtGui More...
#include <qdrag.h>
Inheritance diagram for QDrag: Collaboration diagram for QDrag:Signals | |
| void | actionChanged (Qt::DropAction action) |
| This signal is emitted when the action associated with the drag changes. | |
| void | targetChanged (QObject *newTarget) |
| This signal is emitted when the target of the drag and drop operation changes, with newTarget the new target. | |
| 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. | |
Public Member Functions | |
| QDrag (QObject *dragSource) | |
| Constructs a new drag object for the widget specified by dragSource. | |
| ~QDrag () | |
| Destroys the drag object. | |
| void | setMimeData (QMimeData *data) |
| Sets the data to be sent to the given MIME data. | |
| QMimeData * | mimeData () const |
| Returns the MIME data that is encapsulated by the drag object. | |
| void | setPixmap (const QPixmap &) |
| Sets pixmap as the pixmap used to represent the data in a drag and drop operation. | |
| QPixmap | pixmap () const |
| Returns the pixmap used to represent the data in a drag and drop operation. | |
| void | 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. | |
| QPoint | hotSpot () const |
| Returns the position of the hot spot relative to the top-left corner of the cursor. | |
| QObject * | source () const |
| Returns the source of the drag object. | |
| QObject * | target () const |
| Returns the target of the drag and drop operation. | |
| Qt::DropAction | exec (Qt::DropActions supportedActions=Qt::MoveAction) |
| Qt::DropAction | exec (Qt::DropActions supportedActions, Qt::DropAction defaultAction) |
| void | setDragCursor (const QPixmap &cursor, Qt::DropAction action) |
| Sets the drag cursor for the action. | |
| QPixmap | dragCursor (Qt::DropAction action) const |
| Returns the drag cursor for the action. | |
| Qt::DropActions | supportedActions () const |
| Returns the set of possible drop actions for this drag operation. | |
| Qt::DropAction | defaultAction () const |
| Returns the default proposed drop action for this drag operation. | |
| 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. | |
| virtual bool | eventFilter (QObject *watched, QEvent *event) |
| Filters events if this object has been installed as an event filter for the watched object. | |
| 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. | |
Static Public Member Functions | |
| static void | cancel () |
| Cancels a drag operation initiated by Qt. | |
| 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) |
Friends | |
| class | QDragManager |
Additional Inherited Members | |
| Public Slots inherited from QObject | |
| void | deleteLater () |
| \threadsafe | |
| 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 inherited from QObject | |
| QScopedPointer< QObjectData > | d_ptr |
| 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) | |
\inmodule QtGui
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 Qt 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:
Note that setMimeData() assigns ownership of the QMimeData object to the QDrag object. The QDrag must be constructed on the heap with a parent QObject to ensure that Qt 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:
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 \l{QWidget::mousePressEvent()}{mousePressEvent()} to determine whether the user has pressed a mouse button, and reimplement \l{QWidget::mouseMoveEvent()}{mouseMoveEvent()} to check whether a QDrag is required.
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explicit |
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signal |
This signal is emitted when the action associated with the drag changes.
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static |
| Qt::DropAction QDrag::defaultAction | ( | ) | const |
Returns the default proposed drop action for this drag operation.
| QPixmap QDrag::dragCursor | ( | Qt::DropAction | action | ) | const |
| Qt::DropAction QDrag::exec | ( | Qt::DropActions | supportedActions, |
| Qt::DropAction | defaultDropAction ) |
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 defaultDropAction determines which action will be proposed when the user performs a drag without using modifier keys.
{Note:} On Linux and \macos, 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 Qt 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 \macos, 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 Qt event loop is blocked during the operation.
| QPoint QDrag::hotSpot | ( | ) | const |
| QMimeData * QDrag::mimeData | ( | ) | const |
| QPixmap QDrag::pixmap | ( | ) | const |
| 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.
Note: setting the drag cursor for IgnoreAction may not work on all platforms. X11 and macOS has been tested to work. Windows does not support it.
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.
| QObject * QDrag::source | ( | ) | const |
| Qt::DropActions QDrag::supportedActions | ( | ) | const |
Returns the set of possible drop actions for this drag operation.
| QObject * QDrag::target | ( | ) | const |
This signal is emitted when the target of the drag and drop operation changes, with newTarget the new target.
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friend |
1.12.0