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 that can be OR'ed together when calling functions such as invalidate() or QGraphicsView::invalidateScene().

See also

invalidate(), QGraphicsView::invalidateScene()

Constructs a QGraphicsScene object. The parent parameter is passed to QObject's constructor.

Constructs a QGraphicsScene object, using sceneRect for its scene rectangle. The parent parameter is passed to QObject's 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 parameter is passed to QObject's 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's global scene list, and it is removed from all associated views.

Returns the current active panel, or 0 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 the item pointer. The geometry of the ellipse is defined by rect, and its pen and brush are initialized to pen and brush.

Note that the item's geometry is provided in item coordinates, and its position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

This convenience function is 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 (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

If the item is already in a different scene, it will first be removed from its old scene, and then added to this scene as a top-level.

QGraphicsScene will send ItemSceneChange notifications to item while it is added to the scene. If item does not currently belong to a scene, only one notification is sent. If it does belong to scene already (i.e., it is moved to this scene), QGraphicsScene will send an addition notification as the item is removed from its previous scene.

If the item is a panel, the scene is active, and there is no active panel in the scene, then the item will be activated.

See also

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

Creates and adds a line item to the scene, and returns the item pointer. The geometry of the line is defined by line, and its pen is initialized to pen.

Note that the item's geometry is provided in item coordinates, and its position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

This convenience function is equivalent to calling addLine(QLineF(x1, y1, x2, y2), pen).

Creates and adds a path item to the scene, and returns the item pointer. The geometry of the path is defined by path, and its pen and brush are initialized to pen and brush.

Note that the item's geometry is provided in item coordinates, and its position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

Creates and adds a pixmap item to the scene, and returns the item pointer. The pixmap is defined by pixmap.

Note that the item's geometry is provided in item coordinates, and its position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

Creates and adds a polygon item to the scene, and returns the item pointer. The polygon is defined by polygon, and its pen and brush are initialized to pen and brush.

Note that the item's geometry is provided in item coordinates, and its position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

Creates and adds a rectangle item to the scene, and returns the item pointer. The geometry of the rectangle is defined by rect, and its pen and brush are initialized to pen and brush.

Note that 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, its top-left corner will be at (50, 50) relative to the origin in the items coordinate system.

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

This convenience function is equivalent to calling addRect(QRectF(x, y, w, h), pen, brush).

Creates and adds a QGraphicsSimpleTextItem to the scene, and returns the item pointer. The text string is initialized to text, and its font is initialized to font.

The item's position is initialized to (0, 0).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

See also

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

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

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back 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).

If the item is visible (i.e., QGraphicsItem::isVisible() returns true), QGraphicsScene will emit changed() once control goes back to the event loop.

Note that widgets with the Qt::WA_PaintOnScreen widget attribute set and widgets that wrap an external application or controller are not supported. Examples are QGLWidget and QAxWidget.

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 that the scene is about to change, and in the second phase all items are notified that they can move. In the first phase, QGraphicsItem::advance() is called passing a value of 0 as an argument, and 1 is passed in the second phase.

See also

QGraphicsItem::advance(), QGraphicsItemAnimation, QTimeLine

Property documentation pending.

Property documentation pending.

This signal is emitted by QGraphicsScene when control reaches the event loop, if the scene content changes. The region parameter contains a list of scene rectangles that indicate the area that has been changed.

See also

QGraphicsView::updateScene()

Removes and deletes all items from the scene, but otherwise leaves the state of the scene unchanged.

See also

addItem()

Clears focus from the scene. If any item has focus when this function is called, it will lose focus, and regain focus again once the scene regains focus.

A scene that does not have focus ignores key events.

See also

hasFocus(), setFocus(), setFocusItem()

Clears the current selection.

See also

setSelectionArea(), selectedItems()

Returns a list of all items that collide with item. Collisions are determined by calling QGraphicsItem::collidesWithItem(). The collision detection is determined by mode. By default all items whose shape intersects item or is contained inside the item's shape are returned.

The items are returned in descending stacking order. This means the first item in the list is the uppermost item, and the last item is the lowermost item.

See also

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

This event handler, for event event, can be reimplemented in a subclass to receive context menu events. The default implementation forwards the event to the topmost item that 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 in items into a new QGraphicsItemGroup, and returns a pointer to the group. The group is created with the common ancestor of items as its parent, and with position (0, 0). The items are all reparented to the group, and their positions and transformations are mapped to the group. If items is empty, this function will return an empty top-level QGraphicsItemGroup.

QGraphicsScene has ownership of the group item; you do not need to delete it. To dismantle (ungroup) a group, call destroyItemGroup().

See also

destroyItemGroup(), QGraphicsItemGroup::addToGroup()

Reparents all items in group to its parent item, then removes group from the scene, and finally deletes it. The items positions and transformations are mapped from the group to the group's parent.

See also

createItemGroup(), QGraphicsItemGroup::removeFromGroup()

This event handler, for event 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()

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

See also

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

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

See also

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

Draws the background of the scene using painter, before any items and the foreground are drawn. Reimplement this function to provide a custom background for the scene.

All painting is done in scene coordinates. The rect parameter is the exposed rectangle.

If all you want is to define a color, texture, or gradient for the background, you can call setBackgroundBrush() instead.

See also

drawForeground(), drawItems()

Draws the foreground of the scene using painter, after the background and all items have been drawn. Reimplement this function to provide a custom foreground for the scene.

All painting is done in scene coordinates. The rect parameter is the exposed rectangle.

If all you want is to define a color, texture or gradient for the foreground, you can call setForegroundBrush() instead.

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.

Example:

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

See also

drawBackground(), drawForeground()

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

See also

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

Processes the event event, and dispatches it to the respective event handlers.

In addition to calling the convenience event handlers, this function 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; there is no convenience function for them.

Unlike QWidget, QGraphicsScene does not have the convenience functions enterEvent() and leaveEvent(). Use this function to obtain those events instead.

See also

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

Reimplemented from QObject.

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

Reimplemented from QObject.

This event handler, for event event, can be reimplemented in a subclass 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 functions returns the scene's current focus item, or 0 if no item currently has focus. When the scene is inactive, this functions returns the item that 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 whenever 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 keep track of when other items gain input focus. It is particularly useful for implementing virtual keyboards, input methods, and cursor items.

The value for oldFocus is a pointer to the item which previously had focus or 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 nullptr if focus was lost. The value for reason is the reason for the focus change. For example, if the scene was deactivated while an input field had focus, oldFocus would point to the input field item, newFocus would be nullptr, and reason would be Qt::ActiveWindowFocusReason.

Finds a new widget to give the keyboard focus to, as appropriate for Tab and Shift+Tab, and returns true if it can find a new widget, or false if it can not. If next is true, this function searches forward; if next is false, it searches backward.

You can reimplement this function in a subclass of QGraphicsScene to provide fine-grained control over how tab focus passes inside your scene. The default implementation is based on the tab focus chain defined by QGraphicsWidget::setTabOrder().

This event handler, for event event can be reimplemented in a subclass to receive focus out events. The default implementation removes focus from any focus item, then removes focus from the scene.

See also

QGraphicsItem::focusInEvent()

Property documentation pending.

Property documentation pending.

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

See also

setFocus(), setFocusItem()

This convenience function is 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 topmost item, i.e., the item with the highest z-value, at the mouse cursor position. If no item has a tooltip set, this function 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, this function does nothing.

See also

QGraphicsItem::inputMethodEvent()

This method is used by input methods to query a set of properties of the scene to be able to support complex input method operations as support for surrounding text and reconversions.

The query parameter 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.

You can use this function overload to notify QGraphicsScene of changes to the background or the foreground of the scene. This function is commonly used for scenes with tile-based backgrounds to notify changes when QGraphicsView has enabled CacheBackground.

Note that QGraphicsView currently supports background caching only (see QGraphicsView::CacheBackground). This function is equivalent to calling update() if any layer but BackgroundLayer is passed.

See also

QGraphicsView::resetCachedContent()

This convenience function is equivalent to calling invalidate(QRectF(x, y, w, h), layers);

Returns true if the scene is active (e.g., it's viewed by at least one QGraphicsView that is active), otherwise returns false.

See also

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

Property documentation pending.

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

See also

items(), collidingItems(), Sorting

Returns the topmost item at the position specified by (x, y), or 0 if there are no items at this position.

deviceTransform is the transformation that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

This convenience function is equivalent to calling itemAt(QPointF(x, y), deviceTransform).

Property documentation pending.

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 that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

See also

itemAt(), Sorting

Returns all visible items that, depending on mode, are at the specified pos in 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 that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

See also

itemAt(), Sorting

Returns all visible items that, depending on mode, are either inside or intersect with the specified polygon 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 polygon are returned.

deviceTransform is the transformation that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

See also

itemAt(), Sorting

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 that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

See also

itemAt(), Sorting

Returns all visible items that, depending on mode, are either inside or intersect with the rectangle defined by x, y, w and h, in a list sorted using order.

deviceTransform is the transformation that applies to the view, and needs to be provided if the scene contains items that ignore transformations.

Returns an ordered list of all items on the scene. order decides the stacking order.

See also

addItem(), removeItem(), Sorting

Calculates and returns the bounding rect of all items on the scene. This function works by iterating over all items, and because if this, it can be slow for large scenes.

See also

sceneRect()

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

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()

Property documentation pending.

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

If someone doubleclicks on the scene, the scene will first receive a mouse press event, followed by a release event (i.e., a click), then a doubleclick event, and finally a release event. If the doubleclick event is delivered to a different item than the one that received the first press and release, it will be delivered as a press event. However, tripleclick events are not delivered as doubleclick events in this case.

The default implementation is similar to mousePressEvent().

See also

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

Returns the current mouse grabber item or nullptr if no item is currently grabbing the mouse. The mouse grabber item is the item that receives all mouse events sent to the scene.

An item becomes a mouse grabber when it receives and accepts a mouse press event, and it stays the mouse grabber until either of the following events occur:

• If the item receives a mouse release event when there are no other buttons pressed, it loses the mouse grab.
• If the item becomes invisible (i.e., someone calls item->setVisible(false)), or if it becomes disabled (i.e., someone calls item->setEnabled(false)), it loses the mouse grab.
• If the item is removed from the scene, it loses the mouse grab.

If the item loses its mouse grab, the scene will ignore all mouse events until a new item grabs the mouse (i.e., until a new item receives a mouse press event).

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 that accept hover events at the current position, the event is translated into a hover event and accepted, otherwise it's 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.

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 topmost item that accepts mouse events at the scene position from the event, and that item promptly becomes the mouse grabber item.

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.

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, if there is a mouse grabber item, 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()

Property documentation pending.

Removes the item item and all its children from the scene. The ownership of item is passed on to the caller (i.e., QGraphicsScene will no longer delete item when destroyed).

See also

addItem()

Renders the source rectangle from the current scene into target, using painter. This method is useful for capturing 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 methods will use sceneRect() to determine what to render. If target is a null rectangle the 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()

Property documentation pending.

This signal is emitted by QGraphicsScene whenever the scene rect changes. The rect parameter 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 that 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. You can call selectedItems() to get 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, 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 if you add or remove from the scene a parent item that contains several selected items, selectionChanged() is emitted only once after the operation has completed (instead of once for each item).

See also

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

Sends event event to item> through possible 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 that was returned from the event handler.

See also

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

Activates item, which must be an item in this scene. You can also pass 0 for item, in which case QGraphicsScene will deactivate any currently active panel.

If the scene is currently inactive, item remains inactive until the scene becomes active (or, if item is 0, no item will be activated).

See also

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

Activates widget, which must be a widget in this scene. You can also pass a nullptr for widget, in which case QGraphicsScene will deactivate any currently active window.

See also

activeWindow(), QGraphicsWidget::isActiveWindow()

Property documentation pending.

Property documentation pending.

Sets focus on the scene by sending a QFocusEvent to the scene, passing focusReason as the reason. If the scene regains focus after having previously lost it 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 focus reason focusReason.

This is done after removing focus from any previous item. If item is a nullptr, does not accept focus, or is not visible or not enabled, this method only removes focus from any previous item.

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

See also

focusItem(), hasFocus(), setFocus()

Property documentation pending.

Property documentation pending.

Property documentation pending.

Property documentation pending.

Property documentation pending.

Property documentation pending.

Property documentation pending.

Sets the selection area to path. All items within this area are immediately selected, and all items outside are unselected. You can get the list of all selected items by calling selectedItems().

The deviceTransform is the transformation that applies to the view and needs to be provided if the scene contains items that 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 that applies to the view and needs to be provided if the scene contains items that ignore transformations.

See also

clearSelection(), selectionArea()

Property documentation pending.

Property documentation pending.

Sets or replaces the style of the scene to style, and reparents the style to this scene. Any previously assigned style is deleted. The scene's style defaults to QApplication::style(), and serves as the default for all QGraphicsWidget items in the scene.

Changing the style, either directly by calling this function, or indirectly by calling QApplication::setStyle(), will automatically update the style for all widgets in the scene that do not have a style explicitly assigned to them.

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

See also

style()

Property documentation pending.

Returns the scene's style, or the same as QApplication::style() if the scene has not been explicitly assigned a style.

See also

setStyle()

Schedules a redraw of the area rect on the scene.

See also

sceneRect(), changed()

This function is equivalent to calling update(QRectF(x, y, w, h));

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

See also

QGraphicsView::scene()

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

By default, the event is delivered to the topmost visible item under the cursor. If ignored, the event propagates to the item beneath, and again until the event is accepted, or it reaches the scene. If no items accept the event, it is ignored.

See also

QGraphicsItem::wheelEvent()

This convenience function is 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 before (behind) the items.

QGraphicsScene::render() calls drawBackground() to draw the scene background. For more detailed control over how the background is drawn, you can reimplement drawBackground() in a subclass of QGraphicsScene.

This property holds the depth of QGraphicsScene's BSP index tree.

This property has no effect when NoIndex is used.

This value determines the depth of QGraphicsScene's BSP tree. The depth directly affects QGraphicsScene's performance and memory usage; the latter growing exponentially with the depth of the tree. With an optimal tree depth, QGraphicsScene 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 CopperSpice 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 QGraphicsScene reconfigures 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

itemIndexMethod

This property holds the scene's default font.

The scene font defaults to, and resolves all its entries from, QApplication::font.

If the scene's font changes, either directly through setFont() or indirectly when the application font changes, QGraphicsScene first sends itself a FontChange event, and it then sends FontChange events to all top-level widget items in the scene. These items respond by resolving their own fonts to the scene, and they then notify their children, who again notify their children, and so on, until all widget items have updated their fonts.

Changing the scene font (directly or indirectly through QApplication::setFont(),) automatically schedules a redraw the entire scene.

See also

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

This property holds the foreground brush of the scene.

Change this property to set the scene's foreground to a different color, gradient or texture. The foreground is drawn after (on top of) the items. The default foreground brush is Qt::NoBrush ( i.e. the foreground is not drawn).

QGraphicsScene::render() calls drawForeground() to draw the scene foreground. For more detailed control over how the foreground is drawn, you can reimplement the drawForeground() function in a QGraphicsScene subclass.

This property holds the item indexing method.

QGraphicsScene applies an indexing algorithm to the scene, to speed up item discovery functions like items() and itemAt(). Indexing is most efficient for static scenes (i.e., where items do not move around). For dynamic scenes, or scenes with many animated items, the index bookkeeping can outweigh the fast lookup speeds.

For the common case, the default index method BspTreeIndex works fine. If your scene uses many animations and you are experiencing slowness, you can disable indexing by calling setItemIndexMethod(NoIndex).

See also

bspTreeDepth

When the scene is rendered, any item whose width or height, transformed to the target view, is smaller that minimumRenderSize(), will not be rendered. If an item is not rendered and it clips its children items they will also not be rendered. Set this value to speed up rendering of scenes with many objects rendered on a zoomed out view.

The default value is 0. If unset, or if set to 0 or a negative value, all items will always be rendered.

For example, setting this property can be especially useful if a scene is rendered by multiple views, one of which serves as an overview which always displays all items. In scenes with many items, such a view will use a high scaling factor so that all items can be shown. Due to the scaling, smaller items will only make an insignificant contribution to the final rendered scene. To avoid drawing these items and reduce the time necessary to render the scene, you can call setMinimumRenderSize() with a non-negative value.

Note

Items that 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. It is recommended that you set minimumRenderSize() to a value less than or equal to 1 in order to avoid large unrendered items that are interactive.

See also

QStyleOptionGraphicsItem::levelOfDetailFromTransform()

This property holds the scene's default palette. This property provides the scene's palette. The scene palette defaults to, and resolves all its entries from, QApplication::palette.

If the scene's palette changes, either directly through setPalette() or indirectly when the application palette changes, QGraphicsScene first sends itself a PaletteChange event, and it then sends PaletteChange events to all top-level widget items in the scene. These items respond by resolving their own palettes to the scene, and they then notify their children, who again notify their children, and so on, until all widget items have updated their palettes.

Changing the scene palette, (directly or indirectly through QApplication::setPalette(),) automatically schedules a redraw the entire scene.

See also

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

This property holds the scene rectangle the bounding rectangle of the scene. The scene rectangle defines the extent of the scene. It is primarily used by QGraphicsView to determine the view's default scrollable area, and by Graphicness to manage item indexing.

If unset, or if set to a null QRectF, sceneRect() will return the largest bounding rect of all items on the scene since the scene was created (i.e., a rectangle that grows when items are added to or moved in the scene, but never shrinks).

See also

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

This property holds whether clicking into the scene background will clear focus.

In a QGraphicsScene with stickyFocus set to true, focus will remain unchanged when the user clicks into the scene background or on an item that does not accept focus. Otherwise, focus will be cleared.

By default this property is false.

Focus changes in response to a mouse press. You can reimplement mousePressEvent() in a subclass of QGraphicsScene to toggle this property based on where the user has clicked.

See also

clearFocus(), setFocusItem()