The QGraphicsSceneBspTreeIndex class provides an implementation of a BSP indexing algorithm for discovering items in QGraphicsScene. More...

#include <qgraphicsscenebsptreeindex_p.h>

Inheritance diagram for QGraphicsSceneBspTreeIndex:

Collaboration diagram for QGraphicsSceneBspTreeIndex:

Public Member Functions
	QGraphicsSceneBspTreeIndex (QGraphicsScene *scene=nullptr)
	Constructs a BSP scene index for the given scene.

	~QGraphicsSceneBspTreeIndex ()

QList< QGraphicsItem * >	estimateItems (const QRectF &rect, Qt::SortOrder order) const override
	Returns an estimation visible items that are either inside or intersect with the specified rect and return a list sorted using order.

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

QList< QGraphicsItem * >	items (Qt::SortOrder order=Qt::DescendingOrder) const override
	Return all items in the BSP index and sort them using order.

int	bspTreeDepth () const

void	setBspTreeDepth (int depth)

Public Member Functions inherited from QGraphicsSceneIndex
	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 (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.

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	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`.

Protected Slots
void	updateSceneRect (const QRectF &rect) override

Protected Slots inherited from QGraphicsSceneIndex
virtual void	updateSceneRect (const QRectF &rect)
	Notifies the index that the scene's scene rect has changed.

Protected Member Functions
bool	event (QEvent *event) override
	\reimp

void	clear () override

void	addItem (QGraphicsItem *item) override
	Add the item into the BSP index.

void	removeItem (QGraphicsItem *item) override
	Remove the item from the BSP index.

void	prepareBoundingRectChange (const QGraphicsItem *item) override

void	itemChange (const QGraphicsItem item, QGraphicsItem::GraphicsItemChange change, const void const value) override

Protected Member Functions inherited from QGraphicsSceneIndex
virtual void	deleteItem (QGraphicsItem *item)
	This method is called when an item has been deleted.

	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)

Properties
int	bspTreeDepth
	the depth of the BSP index tree

Properties inherited from QObject
QString	objectName
	the name of this object

Friends
class	QGraphicsScenePrivate

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

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

The QGraphicsSceneBspTreeIndex class provides an implementation of a BSP indexing algorithm for discovering items in QGraphicsScene.

Since: 4.6

QGraphicsSceneBspTreeIndex index use a BSP(Binary Space Partitioning) implementation to discover items quickly. This implementation is very efficient for static scenes. It has a depth that you can set. The depth directly affects performance and memory usage; the latter growing exponentially with the depth of the tree. With an optimal tree depth, the index can instantly determine the locality of items, even for scenes with thousands or millions of items. This also greatly improves rendering performance.

By default, the depth value is 0, in which case Qt will guess a reasonable default depth based on the size, location and number of items in the scene. If these parameters change frequently, however, you may experience slowdowns as the index retunes the depth internally. You can avoid potential slowdowns by fixating the tree depth through setting this property.

The depth of the tree and the size of the scene rectangle decide the granularity of the scene's partitioning. The size of each scene segment is determined by the following algorithm:

The BSP tree has an optimal size when each segment contains between 0 and 10 items.

See also: QGraphicsScene, QGraphicsView, QGraphicsSceneIndex

Definition at line 36 of file qgraphicsscenebsptreeindex_p.h.

Constructor & Destructor Documentation

◆ QGraphicsSceneBspTreeIndex()

QGraphicsSceneBspTreeIndex::QGraphicsSceneBspTreeIndex ( QGraphicsScene * scene = nullptr )

Constructs a BSP scene index for the given scene.

Definition at line 408 of file qgraphicsscenebsptreeindex.cpp.

◆ ~QGraphicsSceneBspTreeIndex()

QGraphicsSceneBspTreeIndex::~QGraphicsSceneBspTreeIndex ( )

Definition at line 414 of file qgraphicsscenebsptreeindex.cpp.

References d, QGraphicsItem::d_ptr, i, QGraphicsItemPrivate::index, item, QGraphicsItemPrivate::itemDiscovered, and Q_ASSERT.

Member Function Documentation

◆ addItem()

void QGraphicsSceneBspTreeIndex::addItem ( QGraphicsItem * item )

overrideprotectedvirtual

Add the item into the BSP index.

Implements QGraphicsSceneIndex.

Definition at line 452 of file qgraphicsscenebsptreeindex.cpp.

References d, and item.

◆ bspTreeDepth()

int QGraphicsSceneBspTreeIndex::bspTreeDepth ( ) const

Definition at line 561 of file qgraphicsscenebsptreeindex.cpp.

References d.

◆ clear()

void QGraphicsSceneBspTreeIndex::clear ( )

overrideprotectedvirtual

Clear the all the BSP index.

Reimplemented from QGraphicsSceneIndex.

Definition at line 430 of file qgraphicsscenebsptreeindex.cpp.

References d, QGraphicsItem::d_ptr, i, QGraphicsItemPrivate::index, item, QGraphicsItemPrivate::itemDiscovered, and Q_ASSERT.

◆ estimateItems()

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

overridevirtual

Returns an estimation visible items that are either inside or intersect with the specified rect and return a list sorted using order.

deviceTransform is the transformation apply to the view.

Implements QGraphicsSceneIndex.

Definition at line 496 of file qgraphicsscenebsptreeindex.cpp.

References d, estimateItems(), and rect.

Referenced by estimateItems(), and estimateTopLevelItems().

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◆ estimateTopLevelItems()

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

overridevirtual

Reimplemented from QGraphicsSceneIndex.

Definition at line 502 of file qgraphicsscenebsptreeindex.cpp.

References d, estimateItems(), and rect.

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◆ event()

bool QGraphicsSceneBspTreeIndex::event ( QEvent * event )

overrideprotectedvirtual

\reimp

Used to catch the timer event.

Reimplemented from QObject.

Definition at line 656 of file qgraphicsscenebsptreeindex.cpp.

References d, QObject::event(), QEvent::Timer, and QTimerEvent::timerId().

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◆ itemChange()

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

overrideprotectedvirtual

This method react to the change of the item and use the value to update the BSP tree if necessary.

Reimplemented from QGraphicsSceneIndex.

Definition at line 595 of file qgraphicsscenebsptreeindex.cpp.

References QGraphicsItemPrivate::AncestorClipsChildren, QGraphicsItemPrivate::AncestorContainsChildren, QGraphicsItemPrivate::ancestorFlags, d, QGraphicsItem::d_ptr, QGraphicsItemPrivate::flags, item, QGraphicsItem::ItemClipsChildrenToShape, QGraphicsItem::ItemContainsChildrenInShape, QGraphicsItem::ItemFlagsChange, QGraphicsItem::ItemIgnoresTransformations, QGraphicsItemPrivate::itemIsUntransformable(), QGraphicsItem::ItemParentChange, and QGraphicsItem::ItemZValueChange.

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◆ items()

QList< QGraphicsItem * > QGraphicsSceneBspTreeIndex::items ( Qt::SortOrder order = Qt::DescendingOrder ) const

overridevirtual

Return all items in the BSP index and sort them using order.

Implements QGraphicsSceneIndex.

Definition at line 513 of file qgraphicsscenebsptreeindex.cpp.

References d.

◆ prepareBoundingRectChange()

void QGraphicsSceneBspTreeIndex::prepareBoundingRectChange ( const QGraphicsItem * item )

overrideprotectedvirtual

Update the BSP when the item 's bounding rect has changed.

Reimplemented from QGraphicsSceneIndex.

Definition at line 471 of file qgraphicsscenebsptreeindex.cpp.

References QGraphicsItemPrivate::AncestorClipsChildren, QGraphicsItemPrivate::AncestorContainsChildren, QGraphicsItemPrivate::ancestorFlags, QList< T >::at(), QGraphicsItemPrivate::children, d, QGraphicsItem::d_ptr, i, QGraphicsItemPrivate::index, item, QGraphicsItemPrivate::itemIsUntransformable(), prepareBoundingRectChange(), and QList< T >::size().

Referenced by prepareBoundingRectChange().

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◆ removeItem()

void QGraphicsSceneBspTreeIndex::removeItem ( QGraphicsItem * item )

overrideprotectedvirtual

Remove the item from the BSP index.

Implements QGraphicsSceneIndex.

Definition at line 461 of file qgraphicsscenebsptreeindex.cpp.

References d, and item.

◆ setBspTreeDepth()

void QGraphicsSceneBspTreeIndex::setBspTreeDepth ( int depth )

Definition at line 567 of file qgraphicsscenebsptreeindex.cpp.

References d.

◆ updateSceneRect

void QGraphicsSceneBspTreeIndex::updateSceneRect ( const QRectF & rect )

overrideprotectedslot

This method react to the rect change of the scene and reset the BSP tree index.

Definition at line 582 of file qgraphicsscenebsptreeindex.cpp.

References d, and rect.

Friends And Related Symbol Documentation

◆ QGraphicsScenePrivate

friend class QGraphicsScenePrivate

friend

Definition at line 71 of file qgraphicsscenebsptreeindex_p.h.

Property Documentation

◆ bspTreeDepth

QGraphicsSceneBspTreeIndex::bspTreeDepth

readwrite

the depth of the BSP index tree

Since: 4.6

This value determines the depth of BSP tree. The depth directly affects performance and memory usage; the latter growing exponentially with the depth of the tree. With an optimal tree depth, the index can instantly determine the locality of items, even for scenes with thousands or millions of items. This also greatly improves rendering performance.

By default, the value is 0, in which case Qt will guess a reasonable default depth based on the size, location and number of items in the scene. If these parameters change frequently, however, you may experience slowdowns as the index retunes the depth internally. You can avoid potential slowdowns by fixating the tree depth through setting this property.

The depth of the tree and the size of the scene rectangle decide the granularity of the scene's partitioning. The size of each scene segment is determined by the following algorithm:

The BSP tree has an optimal size when each segment contains between 0 and 10 items.

Definition at line 39 of file qgraphicsscenebsptreeindex_p.h.

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

qtbase/src/widgets/graphicsview/qgraphicsscenebsptreeindex_p.h (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/widgets/graphicsview/qgraphicsscenebsptreeindex.cpp (05fc3aef53348fb58be6308076e000825b704e58)

Public Member Functions

Protected Slots

Protected Member Functions

Properties

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QGraphicsSceneBspTreeIndex()

◆ ~QGraphicsSceneBspTreeIndex()

Member Function Documentation

◆ addItem()

◆ bspTreeDepth()

◆ clear()

◆ estimateItems()

◆ estimateTopLevelItems()

◆ event()

◆ itemChange()

◆ items()

◆ prepareBoundingRectChange()

◆ removeItem()

◆ setBspTreeDepth()

◆ updateSceneRect

Friends And Related Symbol Documentation

◆ QGraphicsScenePrivate

Property Documentation

◆ bspTreeDepth