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QGraphicsSceneIndex Class Referenceabstract

The QGraphicsSceneIndex class provides a base class to implement a custom indexing algorithm for discovering items in QGraphicsScene. More...

#include <qgraphicssceneindex_p.h>

Inheritance diagram for QGraphicsSceneIndex:
Collaboration diagram for QGraphicsSceneIndex:

Public Member Functions

 QGraphicsSceneIndex (QGraphicsScene *scene=nullptr)
 Constructs an abstract scene index for a given scene.
virtual ~QGraphicsSceneIndex ()
 Destroys the scene index.
QGraphicsScene * scene () const
 Returns the scene of this index.
virtual QList< QGraphicsItem * > items (Qt::SortOrder order=Qt::DescendingOrder) const =0
 This pure virtual function all items in the index and sort them using order.
virtual QList< QGraphicsItem * > items (const QPointF &pos, Qt::ItemSelectionMode mode, Qt::SortOrder order, const QTransform &deviceTransform=QTransform()) const
 Returns all visible items that, depending on mode, are at the specified pos and return a list sorted using order.
virtual QList< QGraphicsItem * > items (const QRectF &rect, Qt::ItemSelectionMode mode, Qt::SortOrder order, const QTransform &deviceTransform=QTransform()) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Returns all visible items that, depending on mode, are either inside or intersect with the specified rect and return a list sorted using order.
virtual QList< QGraphicsItem * > items (const QPolygonF &polygon, Qt::ItemSelectionMode mode, Qt::SortOrder order, const QTransform &deviceTransform=QTransform()) const
virtual QList< QGraphicsItem * > items (const QPainterPath &path, Qt::ItemSelectionMode mode, Qt::SortOrder order, const QTransform &deviceTransform=QTransform()) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Returns all visible items that, depending on mode, are either inside or intersect with the specified path and return a list sorted using order.
virtual QList< QGraphicsItem * > estimateItems (const QPointF &point, Qt::SortOrder order) const
 This virtual function return an estimation of items at position point.
virtual QList< QGraphicsItem * > estimateItems (const QRectF &rect, Qt::SortOrder order) const =0
virtual QList< QGraphicsItem * > estimateTopLevelItems (const QRectF &, Qt::SortOrder order) const
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 isQmlObjectType () const
 Returns whether the object has been created by the QML engine or ownership has been explicitly set via QJSEngine::setObjectOwnership().
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 Slots

virtual void updateSceneRect (const QRectF &rect)
 Notifies the index that the scene's scene rect has changed.

Protected Member Functions

virtual void clear ()
 This virtual function removes all items in the scene index.
virtual void addItem (QGraphicsItem *item)=0
 This pure virtual function inserts an item to the scene index.
virtual void removeItem (QGraphicsItem *item)=0
 This pure virtual function removes an item to the scene index.
virtual void deleteItem (QGraphicsItem *item)
 This method is called when an item has been deleted.
virtual void itemChange (const QGraphicsItem *item, QGraphicsItem::GraphicsItemChange, const void *const value)
 This virtual function is called by QGraphicsItem to notify the index that some part of the item 's state changes.
virtual void prepareBoundingRectChange (const QGraphicsItem *item)
 Notify the index for a geometry change of an item.
 QGraphicsSceneIndex (QGraphicsSceneIndexPrivate &dd, QGraphicsScene *scene)
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)

Friends

class QGraphicsScene
class QGraphicsScenePrivate
class QGraphicsItem
class QGraphicsItemPrivate
class QGraphicsSceneBspTreeIndex

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 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)
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
 Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
 \macro Q_CLASSINFO(Name, Value)

Detailed Description

The QGraphicsSceneIndex class provides a base class to implement a custom indexing algorithm for discovering items in QGraphicsScene.

Since
4.6

The QGraphicsSceneIndex class provides a base class to implement a custom indexing algorithm for discovering items in QGraphicsScene. You need to subclass it and reimplement addItem, removeItem, estimateItems and items in order to have an functional indexing.

See also
QGraphicsScene, QGraphicsView

Definition at line 39 of file qgraphicssceneindex_p.h.

Constructor & Destructor Documentation

◆ QGraphicsSceneIndex() [1/2]

QGraphicsSceneIndex::QGraphicsSceneIndex ( QGraphicsScene * scene = nullptr)

Constructs an abstract scene index for a given scene.

Definition at line 314 of file qgraphicssceneindex.cpp.

◆ ~QGraphicsSceneIndex()

QGraphicsSceneIndex::~QGraphicsSceneIndex ( )
virtual

Destroys the scene index.

Definition at line 332 of file qgraphicssceneindex.cpp.

◆ QGraphicsSceneIndex() [2/2]

QGraphicsSceneIndex::QGraphicsSceneIndex ( QGraphicsSceneIndexPrivate & dd,
QGraphicsScene * scene )
protected

Definition at line 323 of file qgraphicssceneindex.cpp.

Member Function Documentation

◆ addItem()

virtual void QGraphicsSceneIndex::addItem ( QGraphicsItem * item)
protectedpure virtual

This pure virtual function inserts an item to the scene index.

See also
removeItem(), deleteItem()

Implemented in QGraphicsSceneBspTreeIndex, and QGraphicsSceneLinearIndex.

◆ clear()

void QGraphicsSceneIndex::clear ( )
protectedvirtual

This virtual function removes all items in the scene index.

Reimplemented in QGraphicsSceneBspTreeIndex, and QGraphicsSceneLinearIndex.

Definition at line 525 of file qgraphicssceneindex.cpp.

◆ deleteItem()

void QGraphicsSceneIndex::deleteItem ( QGraphicsItem * item)
protectedvirtual

This method is called when an item has been deleted.

The default implementation calls removeItem. Be careful, if your implementation of removeItem use pure virtual method of QGraphicsItem like boundingRect(), then you should reimplement this method.

See also
addItem(), removeItem()

Definition at line 557 of file qgraphicssceneindex.cpp.

◆ estimateItems() [1/2]

QList< QGraphicsItem * > QGraphicsSceneIndex::estimateItems ( const QPointF & point,
Qt::SortOrder order ) const
virtual

This virtual function return an estimation of items at position point.

This method return a list sorted using order.

Definition at line 481 of file qgraphicssceneindex.cpp.

◆ estimateItems() [2/2]

virtual QList< QGraphicsItem * > QGraphicsSceneIndex::estimateItems ( const QRectF & rect,
Qt::SortOrder order ) const
pure virtual

Implemented in QGraphicsSceneBspTreeIndex, and QGraphicsSceneLinearIndex.

◆ estimateTopLevelItems()

QList< QGraphicsItem * > QGraphicsSceneIndex::estimateTopLevelItems ( const QRectF & rect,
Qt::SortOrder order ) const
virtual

Reimplemented in QGraphicsSceneBspTreeIndex.

Definition at line 486 of file qgraphicssceneindex.cpp.

◆ itemChange()

void QGraphicsSceneIndex::itemChange ( const QGraphicsItem * item,
QGraphicsItem::GraphicsItemChange change,
const void *const value )
protectedvirtual

This virtual function is called by QGraphicsItem to notify the index that some part of the item 's state changes.

By reimplementing this function, your can react to a change, and in some cases, (depending on change,) adjustments in the index can be made.

change is the parameter of the item that is changing. value is the value that changed; the type of the value depends on change.

The default implementation does nothing.

See also
QGraphicsItem::GraphicsItemChange

Reimplemented in QGraphicsSceneBspTreeIndex.

Definition at line 575 of file qgraphicssceneindex.cpp.

◆ items() [1/5]

QList< QGraphicsItem * > QGraphicsSceneIndex::items ( const QPainterPath & path,
Qt::ItemSelectionMode mode,
Qt::SortOrder order,
const QTransform & deviceTransform = QTransform() ) const
virtual

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Returns all visible items that, depending on mode, are either inside or intersect with the specified path and return a list sorted using order.

The default value for mode is Qt::IntersectsItemShape; all items whose exact shape intersects with or is contained by path are returned.

deviceTransform is the transformation apply to the view.

This method use the estimation of the index (estimateItems) and refine the list to get an exact result. If you want to implement your own refinement algorithm you can reimplement this method.

See also
estimateItems()

Definition at line 466 of file qgraphicssceneindex.cpp.

◆ items() [2/5]

QList< QGraphicsItem * > QGraphicsSceneIndex::items ( const QPointF & pos,
Qt::ItemSelectionMode mode,
Qt::SortOrder order,
const QTransform & deviceTransform = QTransform() ) const
virtual

Returns all visible items that, depending on mode, are at the specified pos and return a list sorted using order.

The default value for mode is Qt::IntersectsItemShape; all items whose exact shape intersects with pos are returned.

deviceTransform is the transformation apply to the view.

This method use the estimation of the index (estimateItems) and refine the list to get an exact result. If you want to implement your own refinement algorithm you can reimplement this method.

See also
estimateItems()

Definition at line 366 of file qgraphicssceneindex.cpp.

◆ items() [3/5]

QList< QGraphicsItem * > QGraphicsSceneIndex::items ( const QPolygonF & polygon,
Qt::ItemSelectionMode mode,
Qt::SortOrder order,
const QTransform & deviceTransform = QTransform() ) const
virtual

Definition at line 431 of file qgraphicssceneindex.cpp.

◆ items() [4/5]

QList< QGraphicsItem * > QGraphicsSceneIndex::items ( const QRectF & rect,
Qt::ItemSelectionMode mode,
Qt::SortOrder order,
const QTransform & deviceTransform = QTransform() ) const
virtual

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Returns all visible items that, depending on mode, are either inside or intersect with the specified rect and return a list sorted using order.

The default value for mode is Qt::IntersectsItemShape; all items whose exact shape intersects with or is contained by rect are returned.

deviceTransform is the transformation apply to the view.

This method use the estimation of the index (estimateItems) and refine the list to get an exact result. If you want to implement your own refinement algorithm you can reimplement this method.

See also
estimateItems()

Definition at line 398 of file qgraphicssceneindex.cpp.

◆ items() [5/5]

virtual QList< QGraphicsItem * > QGraphicsSceneIndex::items ( Qt::SortOrder order = Qt::DescendingOrder) const
pure virtual

This pure virtual function all items in the index and sort them using order.

Implemented in QGraphicsSceneBspTreeIndex, and QGraphicsSceneLinearIndex.

◆ prepareBoundingRectChange()

void QGraphicsSceneIndex::prepareBoundingRectChange ( const QGraphicsItem * item)
protectedvirtual

Notify the index for a geometry change of an item.

See also
QGraphicsItem::prepareGeometryChange()

Reimplemented in QGraphicsSceneBspTreeIndex.

Definition at line 587 of file qgraphicssceneindex.cpp.

◆ removeItem()

virtual void QGraphicsSceneIndex::removeItem ( QGraphicsItem * item)
protectedpure virtual

This pure virtual function removes an item to the scene index.

See also
addItem(), deleteItem()

Implemented in QGraphicsSceneBspTreeIndex, and QGraphicsSceneLinearIndex.

◆ scene()

QGraphicsScene * QGraphicsSceneIndex::scene ( ) const

Returns the scene of this index.

Definition at line 340 of file qgraphicssceneindex.cpp.

◆ updateSceneRect

void QGraphicsSceneIndex::updateSceneRect ( const QRectF & rect)
protectedvirtualslot

Notifies the index that the scene's scene rect has changed.

rect is thew new scene rect.

See also
QGraphicsScene::sceneRect()

Definition at line 517 of file qgraphicssceneindex.cpp.

◆ QGraphicsItem

friend class QGraphicsItem
friend

Definition at line 78 of file qgraphicssceneindex_p.h.

◆ QGraphicsItemPrivate

friend class QGraphicsItemPrivate
friend

Definition at line 79 of file qgraphicssceneindex_p.h.

◆ QGraphicsScene

friend class QGraphicsScene
friend

Definition at line 76 of file qgraphicssceneindex_p.h.

◆ QGraphicsSceneBspTreeIndex

friend class QGraphicsSceneBspTreeIndex
friend

Definition at line 80 of file qgraphicssceneindex_p.h.

◆ QGraphicsScenePrivate

friend class QGraphicsScenePrivate
friend

Definition at line 77 of file qgraphicssceneindex_p.h.

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