Typedef for QFlags<SceneLayer>. Refer to QGraphicsScene::SceneLayer for documentation.

This enum describes the indexing algorithms QGraphicsScene provides for managing positional information about items on the scene.

See also

setItemIndexMethod(), bspTreeDepth

This enum describes the rendering layers in a QGraphicsScene. When QGraphicsScene draws the scene contents, it renders each of these layers separately, in order. Each layer represents a flag which can be OR'ed together when calling methods such as QGraphicsScene::invalidate() or QGraphicsView::invalidateScene().

See also

invalidate(), QGraphicsView::invalidateScene()

Constructs a QGraphicsScene object. The parent is passed to the QObject constructor.

Constructs a QGraphicsScene object using sceneRect for the scene rectangle. The parent is passed to the QObject constructor.

See also

sceneRect

Constructs a QGraphicsScene object using the rectangle specified by (x, y), and the given width and height for its scene rectangle. The parent is passed to the QObject constructor.

See also

sceneRect

Removes and deletes all items from the scene object before destroying the scene object. The scene object is removed from the application global scene list and from all associated views.

Returns the current active panel or a nullptr if no panel is currently active.

See also

QGraphicsScene::setActivePanel()

Returns the current active window or nullptr if no window is currently active.

See also

QGraphicsScene::setActiveWindow()

Creates and adds an ellipse item to the scene and returns a pointer to the new item. The geometry of the ellipse is defined by rect and is drawn using pen and brush. The item's geometry is provided in item coordinates and its position is initialized to (0, 0).

If the item is visible then QGraphicsScene will emit the changed() signal once control returns to the event loop.

See also

addLine(), addPath(), addPixmap(), addRect(), addText(), addItem(), addWidget()

Equivalent to calling addEllipse(QRectF(x, y, w, h), pen, brush).

Adds or moves the item and all its children to this scene. This scene takes ownership of the item. If the item is visible QGraphicsScene will emit changed() once control returns to the event loop. If the item is already in a different scene it will first be removed from the old scene and then added to this scene.

QGraphicsScene will send ItemSceneChange notifications to the given item when it is added to the scene. If the given item does not currently belong to a scene only one notification is sent. If it does belong to a scene QGraphicsScene will send an additional notification when the item is removed from its previous scene.

If all of these are true then the item will be activated.

• item is a panel
• current scene is active
• no active panel in the scene

See also

removeItem(), addEllipse(), addLine(), addPath(), addPixmap(), addRect(), addText(), addWidget(), Sorting

Creates and adds a line item to the scene and returns a pointer to the new item. The geometry of the line is defined by line and is drawn using pen. The item's geometry is provided in item coordinates and the position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addPath(), addPixmap(), addRect(), addText(), addItem(), addWidget()

Equivalent to calling addLine(QLineF(x1, y1, x2, y2), pen).

Creates and adds a path item to the scene, and returns a pointer to the new item. The geometry of the path is defined by path and is drawn using pen and brush. The item's geometry is provided in item coordinates and its position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPixmap(), addRect(), addText(), addItem(), addWidget()

Creates and adds the pixmap item to the scene and returns a pointer to the new item. The item's geometry is provided in item coordinates and its position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPath(), addRect(), addText(), addItem(), addWidget()

Creates and adds a polygon item to the scene, and returns a pointer to the new item. The polygon is defined by polygon and is drawn using pen and brush. The item's geometry is provided in item coordinates and its position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPath(), addRect(), addText(), addItem(), addWidget()

Creates and adds a rectangle item to the scene and returns a pointer to the new item. The geometry of the rectangle is defined by rect and is drawn using pen and brush. The item's geometry is provided in item coordinates, and its position is initialized to (0, 0). For example, if a QRect(50, 50, 100, 100) is added the top-left corner will be at (50, 50) relative to the origin in the items coordinate system.

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPixmap(), addPixmap(), addText(), addItem(), addWidget()

Equivalent to calling addRect(QRectF(x, y, w, h), pen, brush).

Creates and adds a QGraphicsSimpleTextItem to the scene and returns a pointer to the new item. The text string is initialized to text and is drawn using font. The item's position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPixmap(), addPixmap(), addRect(), addItem(), addWidget()

Creates and adds a text item to the scene, and returns a pointer to the new item. The text string is initialized to text and is drawn using font. The item's position is initialized to (0, 0).

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPixmap(), addPixmap(), addRect(), addItem(), addWidget()

Creates a new QGraphicsProxyWidget for widget, adds it to the scene, and then returns a pointer to the proxy. The value for flags sets the default window flags for the embedding proxy widget. The item's position is initialized to (0, 0). Widgets with the Qt::WA_PaintOnScreen widget attribute set and widgets which wrap an external application or controller are not supported.

If the item is visible QGraphicsScene will emit changed() once control returns to the event loop.

See also

addEllipse(), addLine(), addPixmap(), addPixmap(), addRect(), addText(), addSimpleText(), addItem()

This slot advances the scene by one step by calling QGraphicsItem::advance() for all items on the scene. This is done in two phases. In the first phase all items are notified the scene is about to change. In the second phase all items are notified the items can move.

See also

QGraphicsItem::advance(), QGraphicsItemAnimation, QTimeLine

Returns the value of the backgroundBrush property.

Returns the value of the bspTreeDepth property.

This signal is emitted by QGraphicsScene when control reaches the event loop if the scene content has changed. The region is a list of scene rectangles where the scene has changed.

See also

QGraphicsView::updateScene()

Removes and deletes all items from the current scene. The properties of the scene are not changed.

See also

addItem()

Clears focus from the scene. If any item has focus when this method is called it will lose focus and regain focus again once the scene regains focus. A scene which does not have focus ignores all key events.

See also

hasFocus(), setFocus(), setFocusItem()

Clears the current selection.

See also

setSelectionArea(), selectedItems()

Returns a list of all items which collide with item based on the given collision detection mode. Collisions are detected by calling QGraphicsItem::collidesWithItem(). The items are returned in order with the first element corresponding to the item in front.

See also

items(), itemAt(), QGraphicsItem::collidesWithItem(), Sorting

The event handler for the given event can be reimplemented in a subclass to receive context menu events. The default implementation forwards the event to the item in front which accepts context menu events at the position of the event. If no items accept context menu events at this position the event is ignored.

See also

QGraphicsItem::contextMenuEvent()

Groups all items into a new QGraphicsItemGroup and returns a pointer to the new group. The group is created with the common ancestor of items as its parent and with position (0, 0). The items become children of the new group. Their positions and transformations are mapped to the group. If items is empty this method will return an empty QGraphicsItemGroup.

QGraphicsScene has ownership of the group item so your code should not delete it. To remove the itmes from the group call destroyItemGroup().

See also

destroyItemGroup(), QGraphicsItemGroup::addToGroup()

Sets the parent for every item in group to the grand parent. Then the given group is removed from the scene and deleted. The items positions and transformations are mapped from the group to the grand parent.

See also

createItemGroup(), QGraphicsItemGroup::removeFromGroup()

The event handler for the given event can be reimplemented in a subclass to receive drag enter events for the scene. The default implementation accepts the event and prepares the scene to accept drag move events.

See also

QGraphicsItem::dragEnterEvent(), dragMoveEvent(), dragLeaveEvent(), dropEvent()

The event handler for the given event can be reimplemented in a subclass to receive drag leave events for the scene.

See also

QGraphicsItem::dragLeaveEvent(), dragEnterEvent(), dragMoveEvent(), dropEvent()

The event handler for the given event can be reimplemented in a subclass to receive drag move events for the scene.

See also

QGraphicsItem::dragMoveEvent(), dragEnterEvent(), dragLeaveEvent(), dropEvent()

Uses the given painter to draw the background of the scene before any items or the foreground are drawn. All painting is done in scene coordinates. The given rect is the region where the drawing occurs. Inherit QGraphicsScene and then reimplement this method to provide a custom background for the scene. If you only want to define a color, texture, or gradient for the background, then call setBackgroundBrush() instead of using this method.

See also

drawForeground(), drawItems()

Uses the given painter to draw the foreground of the scene after any items or the background are drawn. All painting is done in scene coordinates. The given rect is the region where the drawing occurs. Inherit QGraphicsScene and then reimplement this method to provide a custom foreground for the scene. If you only want to define a color, texture, or gradient for the foreground, then call setForegroundBrush() instead of using this method.

See also

drawBackground(), drawItems()

Deprecated:

Paints the given items using the provided painter, after the background has been drawn, and before the foreground has been drawn. All painting is done in scene coordinates. Before drawing each item, the painter must be transformed using QGraphicsItem::sceneTransform().

The options parameter is the list of style option objects for each item in items. The numItems parameter is the number of items in items and options in options. The widget parameter is optional; if specified, it should point to the widget that is being painted on.

The default implementation prepares the painter matrix, and calls QGraphicsItem::paint() on all items. Reimplement this function to provide custom painting of all items for the scene; gaining complete control over how each item is drawn. In some cases this can increase drawing performance significantly.

This function is not called unless the QGraphicsView::IndirectPainting flag is given as an Optimization flag.

See also

drawBackground(), drawForeground()

The event handler for the given event can be reimplemented in a subclass to receive drop events for the scene.

See also

QGraphicsItem::dropEvent(), dragEnterEvent(), dragMoveEvent(), dragLeaveEvent()

Processes the given event and dispatches it to the respective event handlers. In addition to calling the event handlers this method is responsible for converting mouse move events to hover events for when there is no mouse grabber item. Hover events are delivered directly to items.

QGraphicsScene does not have the methods enterEvent() and leaveEvent(). Override this method to handle these events.

See also

contextMenuEvent(), keyPressEvent(), keyReleaseEvent(), mousePressEvent(), mouseMoveEvent(), mouseReleaseEvent(), mouseDoubleClickEvent(), focusInEvent(), focusOutEvent()

Reimplemented from QObject::event()

QGraphicsScene filters QApplication's events to detect palette and font changes.

Reimplemented from QObject::eventFilter()

The event handler for the given event can be reimplemented to receive focus in events. The default implementation sets focus on the scene and then on the last focus item.

See also

QGraphicsItem::focusOutEvent()

When the scene is active this method returns the item which has keyboard focus or a nullptr if no item currently has focus. When the scene is inactive this methods returns the item which will gain input focus when the scene becomes active. The focus item receives keyboard input when the scene receives a key event.

See also

setFocusItem(), QGraphicsItem::hasFocus(), isActive()

This signal is emitted any time focus changes in the scene. For example, when an item gains or loses input focus, or when focus passes from one item to another. You can connect to this signal to track when other items gain input focus. This can be useful when implementing virtual keyboards, input methods, and cursor items.

The value for oldFocus is a pointer to the item which previously had focus or a nullptr if no item had focus before the signal was emitted. The newFocus is a pointer to the item which has gained input focus or a nullptr if no item has focus. The value for reason indicates why the focus changed. For example, if the scene was deactivated while an input field had focus, oldFocus will point to the input field item, newFocus would be a nullptr, and the reason would be Qt::ActiveWindowFocusReason.

Changes keyboard focus to the next or previous item. Returns true if it can find a new widget or false if it can not. If next is true this method searches forward. If next is false, it searches backward.

Inherit from QGraphicsScene and reimplement this method to provide more control over how tab focus moves in your scene. The default implementation uses the QGraphicsWidget::setTabOrder().

The event handler for the given event can be reimplemented in a subclass to receive focus out events. The default implementation clears the item which has focus then removes focus from the scene.

See also

QGraphicsItem::focusInEvent()

Returns the value of the QGraphicsScene::font property.

Returns the value of the foregroundBrush property.

Returns true if the scene has focus, otherwise returns false. If the scene has focus it will forward key events from QKeyEvent to any item which has focus.

See also

setFocus(), setFocusItem()

Equivalent to calling sceneRect().height().

See also

width()

This event handler for event can be reimplemented in a subclass to receive help events. The events are of type QEvent::ToolTip which are created when a tooltip is requested. The default implementation shows the tooltip of the item in front at the mouse cursor position. If no item at that position has a tooltip set this method does nothing.

See also

QGraphicsItem::toolTip(), QGraphicsSceneHelpEvent

This event handler for event can be reimplemented in a subclass to receive input method events for the scene. The default implementation forwards the event to the focusItem(). If no item currently has focus or the current focus item does not accept input methods then this method does nothing.

See also

QGraphicsItem::inputMethodEvent()

This method is used by input methods to query properties of the scene. The properties are used to support complex input method operations for surrounding text and reconversions. The value for query specifies which property is queried.

See also

QWidget::inputMethodQuery()

Invalidates and schedules a redraw of the layers in rect on the scene. Any cached content in layers is unconditionally invalidated and redrawn. This method can be used to notify QGraphicsScene of changes to the background or the foreground. It is commonly used for scenes with tile-based backgrounds to notify changes when QGraphicsView has enabled CacheBackground.

QGraphicsView only supports caching the background layer. This method is equivalent to calling update() if any layer other than QGraphicsScene::BackgroundLayer is passed.

See also

QGraphicsView::resetCachedContent()

Equivalent to calling invalidate(QRectF(x, y, w, h), layers).

Returns true if the scene is active otherwise returns false.

See also

QGraphicsItem::isActive(), QWidget::isActiveWindow()

Returns the front most visible item at the specified pos or a nullptr if there are no visible items at this position. The deviceTransform is the transformation which applies to the view and needs to be provided if the scene contains items which ignore transformations.

See also

items(), collidingItems(), Sorting

Returns the front most visible item at the position specified by (x, y) or a nullptr if there are no items at this position. The value for deviceTransform is the transformation which applies to the view and needs to be provided if the scene contains items which ignore transformations.

Equivalent to calling itemAt(QPointF(x, y), deviceTransform).

Returns the value of the itemIndexMethod property.

Returns all visible items matching the value of mode and the given path. Returns a list sorted using order. The default value for mode is Qt::IntersectsItemShape where all items whose exact shape intersects with or is contained by path are returned. The deviceTransform applies to the view and needs to be specified if the scene contains items which ignore transformations.

See also

itemAt(), Sorting

Returns all visible items matching the value of mode and the given pos. Returns a list sorted using order. The default value for mode is Qt::IntersectsItemShape where all items whose exact shape intersects with or is contained by pos are returned. The deviceTransform applies to the view and needs to be specified if the scene contains items which ignore transformations.

See also

itemAt(), Sorting

Returns all visible items matching the value of mode and the given polygon. Returns a list sorted using order. The default value for mode is Qt::IntersectsItemShape where all items whose exact shape intersects with or is contained by polygon are returned. The deviceTransform applies to the view and needs to be specified if the scene contains items which ignore transformations.

See also

itemAt(), Sorting

Returns all visible items matching the value of mode and the given rect. Returns a list sorted using order. The default value for mode is Qt::IntersectsItemShape where all items whose exact shape intersects with or is contained by rect are returned. The deviceTransform applies to the view and needs to be specified if the scene contains items which ignore transformations.

See also

itemAt(), Sorting

Returns all visible items matching the value of mode and the rectangle defined by x, y, w and h. Returns a list sorted using order. The default value for mode is Qt::IntersectsItemShape where all items whose exact shape intersects with or is contained by the rectangle are returned. The deviceTransform applies to the view and needs to be specified if the scene contains items which ignore transformations.

Returns a sorted list of all items in the scene. The given order defines which elements will appear first in the list.

See also

addItem(), removeItem(), Sorting

Calculates and returns the bounding rectangle of all items in the scene. This method works by iterating over all items and can be slow for large scenes.

See also

sceneRect()

This event handler for event can be reimplemented in a subclass to receive key press events. The default implementation will forward the event to the item which has focus.

See also

QGraphicsItem::keyPressEvent(), focusItem()

This event handler for event can be reimplemented in a subclass to receive key release events. The default implementation forwards the event to current focus item.

See also

QGraphicsItem::keyReleaseEvent(), focusItem()

Returns the value of the minimumRenderSize property.

This event handler for event can be reimplemented in a subclass to receive mouse doubleclick events. The default implementation is similar to mousePressEvent().

If a user doubleclicks on the scene multiple events are sent. The first will be a mouse press event followed by a release event. Then a doubleclick event and finally a second release event will be sent. If the doubleclick event is delivered to a different item than the one which received the first press and release it will be delivered as a press event. However, tripleclick events are not delivered as doubleclick events.

See also

QGraphicsItem::mousePressEvent(), QGraphicsItem::mouseMoveEvent(), QGraphicsItem::mouseReleaseEvent(), QGraphicsItem::setAcceptedMouseButtons()

Returns the current mouse grabber item or a nullptr if no item is currently grabbing the mouse. The mouse grabber item is the item which receives all mouse events sent to the scene. If the item loses its mouse grab the scene will ignore all mouse events until a new item grabs the mouse.

An item becomes a mouse grabber when it receives and accepts a mouse press event and it continues to be the mouse grabber until one of the following events occur.

• If the item receives a mouse release event when no other buttons are pressed
• If the item becomes invisible or if it becomes disabled
• If the item is removed from the scene

This event handler for event can be reimplemented in a subclass to receive mouse move events for the scene.

The default implementation depends on the mouse grabber state. If there is a mouse grabber item the event is sent to the mouse grabber. If there are any items which accept hover events at the current position, the event is translated into a hover event and accepted, otherwise it is ignored.

See also

QGraphicsItem::mousePressEvent(), QGraphicsItem::mouseReleaseEvent(), QGraphicsItem::mouseDoubleClickEvent(), QGraphicsItem::setAcceptedMouseButtons()

This event handler for event can be reimplemented in a subclass to receive mouse press events for the scene. If there is no item at the given position on the scene the selection area is reset. Any focus item loses its input focus and the event is then ignored.

The default implementation depends on the state of the scene. If there is a mouse grabber item then the event is sent to the mouse grabber. Otherwise, it is forwarded to the front item which accepts mouse events at the cursor position and this item becomes the mouse grabber item.

See also

QGraphicsItem::mousePressEvent(), QGraphicsItem::setAcceptedMouseButtons()

This event handler for event can be reimplemented in a subclass to receive mouse release events for the scene. The default implementation depends on the mouse grabber state. If there is no mouse grabber the event is ignored. Otherwise, the event is sent to the mouse grabber. If this mouse release represents the last pressed button on the mouse the mouse grabber item then loses the mouse grab.

See also

QGraphicsItem::mousePressEvent(), QGraphicsItem::mouseMoveEvent(), QGraphicsItem::mouseDoubleClickEvent(), QGraphicsItem::setAcceptedMouseButtons()

Returns the value of the QGraphicsScene::palette property.

Removes the item and all its children from the scene. The ownership of item is passed to the caller. This means the QGraphicsScene will no longer delete the given item when it is destroyed.

See also

addItem()

Renders the source rectangle from the current scene into the target rectangle using painter. This method is useful for rendering the contents of the scene onto a paint device, such as a QImage or for printing with QPrinter.

If source is a null rectangle this method will call sceneRect() to determine what to render. If target is a null rectangle the full dimensions of the QPainter device will be used. The source rectangle contents will be transformed according to aspectRatioMode to fit into the target rectangle. By default, the aspect ratio is kept and source is scaled to fit in target.

See also

QGraphicsView::render()

Returns the value of the sceneRect property.

This signal is emitted by QGraphicsScene whenever the scene rectangle changes. The given rect is the new scene rectangle.

See also

QGraphicsView::updateSceneRect()

Returns a list of all currently selected items. The items are returned in no particular order.

See also

setSelectionArea()

Returns the selection area which was previously set with setSelectionArea() or an empty QPainterPath if no selection area has been set.

See also

setSelectionArea()

This signal is emitted by QGraphicsScene whenever the selection changes. Call selectedItems() to obtain the new list of selected items. The selection changes whenever an item is selected or unselected, a selection area is set, cleared, or otherwise changed. It also changes if a preselected item is added to the scene or if a selected item is removed from the scene.

QGraphicsScene emits this signal only once for group selection operations. For example, if you set a selection area, select or unselect a QGraphicsItemGroup, or add or remove an item which contains several selected children, this signal is emitted once.

See also

setSelectionArea(), selectedItems(), QGraphicsItem::setSelected()

Sends the given event to item using any installed event filters. The event is sent only if the item is enabled. Returns false if the event was filtered or if the item is disabled. Otherwise returns the value which was returned from the event handler.

See also

QGraphicsItem::sceneEvent(), QGraphicsItem::sceneEventFilter()

Activates the item in this scene. If item is a nullptr then any currently active panel will be deactivated. If the scene is currently inactive item remains inactive until the scene becomes active.

See also

activePanel(), isActive(), QGraphicsItem::isActive()

Activates widget which must be a QGraphicsWidget in the current scene. If widget is a nullptr then QGraphicsScene will deactivate any currently active window.

See also

activeWindow(), QGraphicsWidget::isActiveWindow()

Sets the value of the backgroundBrush property to brush.

Sets the value of the bspTreeDepth property to depth.

Sets focus to the scene by sending a QFocusEvent and passing focusReason. If the scene regains focus after having previously lost focus while an item had focus, the last focus item will receive focus with focusReason as the reason. If the scene already has focus this method does nothing.

See also

hasFocus(), clearFocus(), setFocusItem()

Sets the focus in the current QGraphicsScene to item with the given focusReason. This happens after removing focus from any previous item. If the given item is a nullptr, does not accept focus, is not visible, or is not enabled, then this method only removes focus from any item which currently does have focus.

If item is not a nullptr and the scene does not currently have focus then this method will call QGraphicsScenesetFocus().

See also

focusItem(), hasFocus(), setFocus()

Sets the value of the QGraphicsScene::font property to font.

Sets the value of the foregroundBrush property to brush.

Sets the value of the itemIndexMethod property to method.

Sets the value of the minimumRenderSize property to minSize.

Sets the value of the QGraphicsScene::palette property to palette.

Sets the value of the sceneRect property to rect.

Sets the value of the sceneRect property to x, y, w, h.

Sets the selection area to path. All items within this area are immediately selected and all items outside are unselected. The list of all selected items can be retrieved by calling selectedItems(). The deviceTransform is the transformation which applies to the view and needs to be provided if the scene contains items which ignore transformations. For an item to be selected it must be marked as selectable using QGraphicsItem::ItemIsSelectable.

See also

clearSelection(), selectionArea()

Sets the selection area to path using mode to determine if items are included in the selection area. The selectionOperation determines what to do with the currently selected items. The deviceTransform is the transformation which applies to the view and needs to be provided if the scene contains items which ignore transformations.

See also

clearSelection(), selectionArea()

Sets the value of the stickyFocus property to enabled.

Sets or replaces the style of the scene and makes the style a child of this scene. Any previously assigned style is deleted. The initial style is obtained by calling QApplication::style(). Changing the style, either directly by calling this method or indirectly by calling QApplication::setStyle(), will automatically update the style for all widgets which do not have a style explicitly assigned.

If style is a nullptr QGraphicsScene will revert to QApplication::style().

See also

style()

Returns the value of the stickyFocus property.

Returns the style for this scene. If the scene has not been explicitly assigned a style, the initial style is obtained by calling QApplication::style().

See also

setStyle()

Schedules a redraw of the given rect in the scene.

See also

sceneRect(), changed()

Equivalent to calling update(QRectF(x, y, w, h));

Returns a list of all the views which display this scene.

See also

QGraphicsView::scene()

This event handler for event can be reimplemented in a subclass to receive mouse wheel events. By default, the event is delivered to the front item under the cursor. If the event is ignored it will be passed to the next item and so on, until the event is accepted or it reaches the background of the scene. If no items accept the event it is ignored.

See also

QGraphicsItem::wheelEvent()

Equivalent to calling sceneRect().width().

See also

height()

This property holds the background brush of the scene. Set this property to changes the scene's background to a different color, gradient or texture. The default background brush is Qt::NoBrush. The background is drawn behind all items. QGraphicsScene::render() calls drawBackground() to draw the scene background.

For more detailed control over how the background is drawn reimplement drawBackground() in a subclass of QGraphicsScene.

This property holds the depth of the QGraphicsScene BSP index tree. This tree depth has no effect on the scene when the property itemIndexMethod is set to ItemIndexMethod::NoIndex. The depth affects the performance and memory usage of the index, which will grow exponentially as the depth of the tree increases.

By default the value of this property is 0. When this property is 0 a default depth will be chosen based on the size, location, and number of items in the scene. If the items change frequently you may experience some lag as QGraphicsScene recalculates the depth. To avoid this lag set the tree depth explicitly.

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

itemIndexMethod

This property holds the default font for the scene. The scene font defaults to QApplication::font.

If the font changes, either directly by calling setFont() or indirectly when the application font changes, QGraphicsScene first sends itself a FontChange event. Then it sends FontChange events to all top level widget items in the scene. Changing the scene font automatically schedules a redraw of the entire scene.

See also

style(), palette, QWidget::font, QApplication::setFont()

This property holds the foreground brush of the scene. Change this property to set the foreground to a different color, gradient, or texture. The foreground is drawn in front of the items. The default foreground brush is Qt::NoBrush.

For more detailed control over how the foreground is drawn, reimplement the drawForeground() method in a QGraphicsScene subclass.

This property holds the item indexing method. QGraphicsScene applies an indexing algorithm to the scene, to speed up item discovery methods like items() and itemAt(). Indexing is most efficient for static scenes. For dynamic scenes or scenes with lots of animated items the index overhead can outweigh the fast lookup speeds.

The default index method BspTreeIndex works fine for most applications. If your scene uses lots of animations and you are experiencing some degradation in speed, you can disable indexing by calling setItemIndexMethod(NoIndex).

See also

bspTreeDepth

When the scene is rendered any item whose width or height is smaller than the value of this property will not be rendered. If an item is not rendered and the QGrapicsItem::ItemClipsChildrenToShape flag is set then child items will also not be rendered. The default value is 0. If not set, set to 0, or a negative value, all items will always be rendered.

Adjust this value to speed up rendering of scenes which contain lots of small items. Items which are not drawn as a result of being too small are still returned by methods such as items() and itemAt() and participate in collision detection and interactions. Setting the minimumRenderSize() to a value less than 2 may avoid large unrendered items.

See also

QStyleOptionGraphicsItem::levelOfDetailFromTransform()

This property holds the default palette for the scene. The scene palette default is QApplication::palette.

If the palette changes, either directly by calling setPalette() or indirectly when the application palette changes, QGraphicsScene first sends itself a PaletteChange event. Then it sends PaletteChange events to all top level widget items in the scene. Changing the scene palette automatically schedules a redraw of the entire scene.

See also

style(), font, QWidget::palette, QApplication::setPalette()

This property holds the bounding rectangle of the scene. The sceneRect property is primarily used by QGraphicsView to determine the view's default scrollable area and by QGraphicsScene to manage item indexing.

If this property is not set or set to a null QRectF the sceneRect() method will return the largest bounding rectangle of all items which have ever been added to the scene.

See also

width(), height(), QGraphicsView::sceneRect

This property holds whether clicking on the scene background will clear focus. In a QGraphicsScene with a value of stickyFocus set to true, the item with focus will retain focus when the user clicks on the background. Focus will also be retained when an item does not accept focus. If stickyFocus is set to false any mouse click will clear focus. By default this property is false.

Reimplement mousePressEvent() in a subclass of QGraphicsScene to toggle this property based on where the user has clicked.

See also

clearFocus(), setFocusItem()