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Internal/Contributor docs for the Qt SDK. <b>Note:</b> These are NOT official API docs; those are found <a href='https://doc.qt.io/'>here</a>.
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Public Member Functions | List of all members
SimpleItem Class Reference

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+ Inheritance diagram for SimpleItem:
+ Collaboration diagram for SimpleItem:

Public Member Functions

QRectF boundingRect () const override
 This pure virtual function defines the outer bounds of the item as a rectangle; all painting must be restricted to inside an item's bounding rect.
 
void paint (QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
 This function, which is usually called by QGraphicsView, paints the contents of an item in local coordinates.
 
- Public Member Functions inherited from QGraphicsItem
 QGraphicsItem (QGraphicsItem *parent=nullptr)
 Constructs a QGraphicsItem with the given parent item.
 
virtual ~QGraphicsItem ()
 Destroys the QGraphicsItem and all its children.
 
QGraphicsScene * scene () const
 Returns the current scene for the item, or \nullptr if the item is not stored in a scene.
 
QGraphicsItem * parentItem () const
 Returns a pointer to this item's parent item.
 
QGraphicsItem * topLevelItem () const
 Returns this item's top-level item.
 
QGraphicsObject * parentObject () const
 
QGraphicsWidget * parentWidget () const
 
QGraphicsWidget * topLevelWidget () const
 
QGraphicsWidget * window () const
 
QGraphicsItem * panel () const
 
void setParentItem (QGraphicsItem *parent)
 Sets this item's parent item to newParent.
 
QList< QGraphicsItem * > childItems () const
 
bool isWidget () const
 
bool isWindow () const
 
bool isPanel () const
 
QGraphicsObject * toGraphicsObject ()
 
const QGraphicsObject * toGraphicsObject () const
 
QGraphicsItemGroup * group () const
 Returns a pointer to this item's item group, or \nullptr if this item is not member of a group.
 
void setGroup (QGraphicsItemGroup *group)
 Adds this item to the item group group.
 
GraphicsItemFlags flags () const
 Returns this item's flags.
 
void setFlag (GraphicsItemFlag flag, bool enabled=true)
 If enabled is true, the item flag flag is enabled; otherwise, it is disabled.
 
void setFlags (GraphicsItemFlags flags)
 Sets the item flags to flags.
 
CacheMode cacheMode () const
 
void setCacheMode (CacheMode mode, const QSize &cacheSize=QSize())
 
PanelModality panelModality () const
 
void setPanelModality (PanelModality panelModality)
 
bool isBlockedByModalPanel (QGraphicsItem **blockingPanel=nullptr) const
 
QCursor cursor () const
 Returns the current cursor shape for the item.
 
void setCursor (const QCursor &cursor)
 Sets the current cursor shape for the item to cursor.
 
bool hasCursor () const
 Returns true if this item has a cursor set; otherwise, false is returned.
 
void unsetCursor ()
 Clears the cursor from this item.
 
bool isVisible () const
 Returns true if the item is visible; otherwise, false is returned.
 
bool isVisibleTo (const QGraphicsItem *parent) const
 
void setVisible (bool visible)
 If visible is true, the item is made visible.
 
void hide ()
 Hides the item (items are visible by default).
 
void show ()
 Shows the item (items are visible by default).
 
bool isEnabled () const
 Returns true if the item is enabled; otherwise, false is returned.
 
void setEnabled (bool enabled)
 If enabled is true, the item is enabled; otherwise, it is disabled.
 
bool isSelected () const
 Returns true if this item is selected; otherwise, false is returned.
 
void setSelected (bool selected)
 If selected is true and this item is selectable, this item is selected; otherwise, it is unselected.
 
bool acceptDrops () const
 Returns true if this item can accept drag and drop events; otherwise, returns false.
 
void setAcceptDrops (bool on)
 If on is true, this item will accept drag and drop events; otherwise, it is transparent for drag and drop events.
 
qreal opacity () const
 
qreal effectiveOpacity () const
 
void setOpacity (qreal opacity)
 
Qt::MouseButtons acceptedMouseButtons () const
 Returns the mouse buttons that this item accepts mouse events for.
 
void setAcceptedMouseButtons (Qt::MouseButtons buttons)
 Sets the mouse buttons that this item accepts mouse events for.
 
bool acceptHoverEvents () const
 
void setAcceptHoverEvents (bool enabled)
 
bool acceptTouchEvents () const
 
void setAcceptTouchEvents (bool enabled)
 
bool filtersChildEvents () const
 
void setFiltersChildEvents (bool enabled)
 
bool handlesChildEvents () const
 
void setHandlesChildEvents (bool enabled)
 
bool isActive () const
 
void setActive (bool active)
 
bool hasFocus () const
 Returns true if this item is active, and it or its \l{focusProxy()}{focus proxy} has keyboard input focus; otherwise, returns false.
 
void setFocus (Qt::FocusReason focusReason=Qt::OtherFocusReason)
 Gives keyboard input focus to this item.
 
void clearFocus ()
 Takes keyboard input focus from the item.
 
QGraphicsItem * focusProxy () const
 
void setFocusProxy (QGraphicsItem *item)
 
QGraphicsItem * focusItem () const
 
QGraphicsItem * focusScopeItem () const
 
void grabMouse ()
 
void ungrabMouse ()
 
void grabKeyboard ()
 
void ungrabKeyboard ()
 
QPointF pos () const
 Returns the position of the item in parent coordinates.
 
qreal x () const
 This convenience function is equivalent to calling pos().x().
 
void setX (qreal x)
 
qreal y () const
 This convenience function is equivalent to calling pos().y().
 
void setY (qreal y)
 
QPointF scenePos () const
 Returns the item's position in scene coordinates.
 
void setPos (const QPointF &pos)
 Sets the position of the item to pos, which is in parent coordinates.
 
void setPos (qreal x, qreal y)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling setPos(QPointF(x, y)).
 
void moveBy (qreal dx, qreal dy)
 Moves the item by dx points horizontally, and dy point vertically.
 
void ensureVisible (const QRectF &rect=QRectF(), int xmargin=50, int ymargin=50)
 If this item is part of a scene that is viewed by a QGraphicsView, this convenience function will attempt to scroll the view to ensure that rect is visible inside the view's viewport.
 
void ensureVisible (qreal x, qreal y, qreal w, qreal h, int xmargin=50, int ymargin=50)
 This convenience function is equivalent to calling ensureVisible(QRectF(x, y, w, h), xmargin, ymargin).
 
QTransform transform () const
 
QTransform sceneTransform () const
 
QTransform deviceTransform (const QTransform &viewportTransform) const
 
QTransform itemTransform (const QGraphicsItem *other, bool *ok=nullptr) const
 
void setTransform (const QTransform &matrix, bool combine=false)
 
void resetTransform ()
 
void setRotation (qreal angle)
 
qreal rotation () const
 
void setScale (qreal scale)
 
qreal scale () const
 
QList< QGraphicsTransform * > transformations () const
 
void setTransformations (const QList< QGraphicsTransform * > &transformations)
 
QPointF transformOriginPoint () const
 
void setTransformOriginPoint (const QPointF &origin)
 
void setTransformOriginPoint (qreal ax, qreal ay)
 
virtual void advance (int phase)
 This virtual function is called twice for all items by the QGraphicsScene::advance() slot.
 
qreal zValue () const
 Returns the Z-value of the item.
 
void setZValue (qreal z)
 Sets the Z-value of the item to z.
 
void stackBefore (const QGraphicsItem *sibling)
 
QRectF childrenBoundingRect () const
 Returns the bounding rect of this item's descendants (i.e., its children, their children, etc.) in local coordinates.
 
QRectF sceneBoundingRect () const
 Returns the bounding rect of this item in scene coordinates, by combining sceneTransform() with boundingRect().
 
virtual QPainterPath shape () const
 Returns the shape of this item as a QPainterPath in local coordinates.
 
bool isClipped () const
 Returns true if this item is clipped.
 
QPainterPath clipPath () const
 
virtual bool contains (const QPointF &point) const
 Returns true if this item contains point, which is in local coordinates; otherwise, false is returned.
 
virtual bool collidesWithItem (const QGraphicsItem *other, Qt::ItemSelectionMode mode=Qt::IntersectsItemShape) const
 Returns true if this item collides with other; otherwise returns false.
 
virtual bool collidesWithPath (const QPainterPath &path, Qt::ItemSelectionMode mode=Qt::IntersectsItemShape) const
 Returns true if this item collides with path.
 
QList< QGraphicsItem * > collidingItems (Qt::ItemSelectionMode mode=Qt::IntersectsItemShape) const
 Returns a list of all items that collide with this item.
 
bool isObscured (const QRectF &rect=QRectF()) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 
bool isObscured (qreal x, qreal y, qreal w, qreal h) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 
virtual bool isObscuredBy (const QGraphicsItem *item) const
 Returns true if this item's bounding rect is completely obscured by the opaque shape of item.
 
virtual QPainterPath opaqueArea () const
 This virtual function returns a shape representing the area where this item is opaque.
 
QRegion boundingRegion (const QTransform &itemToDeviceTransform) const
 
qreal boundingRegionGranularity () const
 
void setBoundingRegionGranularity (qreal granularity)
 
void update (const QRectF &rect=QRectF())
 Schedules a redraw of the area covered by rect in this item.
 
void update (qreal x, qreal y, qreal width, qreal height)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling update(QRectF(x, y, width, height)).
 
void scroll (qreal dx, qreal dy, const QRectF &rect=QRectF())
 
QPointF mapToItem (const QGraphicsItem *item, const QPointF &point) const
 Maps the point point, which is in this item's coordinate system, to item's coordinate system, and returns the mapped coordinate.
 
QPointF mapToParent (const QPointF &point) const
 Maps the point point, which is in this item's coordinate system, to its parent's coordinate system, and returns the mapped coordinate.
 
QPointF mapToScene (const QPointF &point) const
 Maps the point point, which is in this item's coordinate system, to the scene's coordinate system, and returns the mapped coordinate.
 
QPolygonF mapToItem (const QGraphicsItem *item, const QRectF &rect) const
 Maps the rectangle rect, which is in this item's coordinate system, to item's coordinate system, and returns the mapped rectangle as a polygon.
 
QPolygonF mapToParent (const QRectF &rect) const
 Maps the rectangle rect, which is in this item's coordinate system, to its parent's coordinate system, and returns the mapped rectangle as a polygon.
 
QPolygonF mapToScene (const QRectF &rect) const
 Maps the rectangle rect, which is in this item's coordinate system, to the scene's coordinate system, and returns the mapped rectangle as a polygon.
 
QRectF mapRectToItem (const QGraphicsItem *item, const QRectF &rect) const
 
QRectF mapRectToParent (const QRectF &rect) const
 
QRectF mapRectToScene (const QRectF &rect) const
 
QPolygonF mapToItem (const QGraphicsItem *item, const QPolygonF &polygon) const
 Maps the polygon polygon, which is in this item's coordinate system, to item's coordinate system, and returns the mapped polygon.
 
QPolygonF mapToParent (const QPolygonF &polygon) const
 Maps the polygon polygon, which is in this item's coordinate system, to its parent's coordinate system, and returns the mapped polygon.
 
QPolygonF mapToScene (const QPolygonF &polygon) const
 Maps the polygon polygon, which is in this item's coordinate system, to the scene's coordinate system, and returns the mapped polygon.
 
QPainterPath mapToItem (const QGraphicsItem *item, const QPainterPath &path) const
 Maps the path path, which is in this item's coordinate system, to item's coordinate system, and returns the mapped path.
 
QPainterPath mapToParent (const QPainterPath &path) const
 Maps the path path, which is in this item's coordinate system, to its parent's coordinate system, and returns the mapped path.
 
QPainterPath mapToScene (const QPainterPath &path) const
 Maps the path path, which is in this item's coordinate system, to the scene's coordinate system, and returns the mapped path.
 
QPointF mapFromItem (const QGraphicsItem *item, const QPointF &point) const
 Maps the point point, which is in item's coordinate system, to this item's coordinate system, and returns the mapped coordinate.
 
QPointF mapFromParent (const QPointF &point) const
 Maps the point point, which is in this item's parent's coordinate system, to this item's coordinate system, and returns the mapped coordinate.
 
QPointF mapFromScene (const QPointF &point) const
 Maps the point point, which is in this item's scene's coordinate system, to this item's coordinate system, and returns the mapped coordinate.
 
QPolygonF mapFromItem (const QGraphicsItem *item, const QRectF &rect) const
 Maps the rectangle rect, which is in item's coordinate system, to this item's coordinate system, and returns the mapped rectangle as a polygon.
 
QPolygonF mapFromParent (const QRectF &rect) const
 Maps the rectangle rect, which is in this item's parent's coordinate system, to this item's coordinate system, and returns the mapped rectangle as a polygon.
 
QPolygonF mapFromScene (const QRectF &rect) const
 Maps the rectangle rect, which is in this item's scene's coordinate system, to this item's coordinate system, and returns the mapped rectangle as a polygon.
 
QRectF mapRectFromItem (const QGraphicsItem *item, const QRectF &rect) const
 
QRectF mapRectFromParent (const QRectF &rect) const
 
QRectF mapRectFromScene (const QRectF &rect) const
 
QPolygonF mapFromItem (const QGraphicsItem *item, const QPolygonF &polygon) const
 Maps the polygon polygon, which is in item's coordinate system, to this item's coordinate system, and returns the mapped polygon.
 
QPolygonF mapFromParent (const QPolygonF &polygon) const
 Maps the polygon polygon, which is in this item's parent's coordinate system, to this item's coordinate system, and returns the mapped polygon.
 
QPolygonF mapFromScene (const QPolygonF &polygon) const
 Maps the polygon polygon, which is in this item's scene's coordinate system, to this item's coordinate system, and returns the mapped polygon.
 
QPainterPath mapFromItem (const QGraphicsItem *item, const QPainterPath &path) const
 Maps the path path, which is in item's coordinate system, to this item's coordinate system, and returns the mapped path.
 
QPainterPath mapFromParent (const QPainterPath &path) const
 Maps the path path, which is in this item's parent's coordinate system, to this item's coordinate system, and returns the mapped path.
 
QPainterPath mapFromScene (const QPainterPath &path) const
 Maps the path path, which is in this item's scene's coordinate system, to this item's coordinate system, and returns the mapped path.
 
QPointF mapToItem (const QGraphicsItem *item, qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapToItem(item, QPointF(x, y)).
 
QPointF mapToParent (qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapToParent(QPointF(x, y)).
 
QPointF mapToScene (qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapToScene(QPointF(x, y)).
 
QPolygonF mapToItem (const QGraphicsItem *item, qreal x, qreal y, qreal w, qreal h) const
 
QPolygonF mapToParent (qreal x, qreal y, qreal w, qreal h) const
 
QPolygonF mapToScene (qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectToItem (const QGraphicsItem *item, qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectToParent (qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectToScene (qreal x, qreal y, qreal w, qreal h) const
 
QPointF mapFromItem (const QGraphicsItem *item, qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapFromItem(item, QPointF(x, y)).
 
QPointF mapFromParent (qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapFromParent(QPointF(x, y)).
 
QPointF mapFromScene (qreal x, qreal y) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This convenience function is equivalent to calling mapFromScene(QPointF(x, y)).
 
QPolygonF mapFromItem (const QGraphicsItem *item, qreal x, qreal y, qreal w, qreal h) const
 
QPolygonF mapFromParent (qreal x, qreal y, qreal w, qreal h) const
 
QPolygonF mapFromScene (qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectFromItem (const QGraphicsItem *item, qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectFromParent (qreal x, qreal y, qreal w, qreal h) const
 
QRectF mapRectFromScene (qreal x, qreal y, qreal w, qreal h) const
 
bool isAncestorOf (const QGraphicsItem *child) const
 Returns true if this item is an ancestor of child (i.e., if this item is child's parent, or one of child's parent's ancestors).
 
QGraphicsItem * commonAncestorItem (const QGraphicsItem *other) const
 
bool isUnderMouse () const
 
QVariant data (int key) const
 Returns this item's custom data for the key key as a QVariant.
 
void setData (int key, const QVariant &value)
 Sets this item's custom data for the key key to value.
 
Qt::InputMethodHints inputMethodHints () const
 Returns the current input method hints of this item.
 
void setInputMethodHints (Qt::InputMethodHints hints)
 Sets the current input method hints of this item to hints.
 
virtual int type () const
 Returns the type of an item as an int.
 
void installSceneEventFilter (QGraphicsItem *filterItem)
 Installs an event filter for this item on filterItem, causing all events for this item to first pass through filterItem's sceneEventFilter() function.
 
void removeSceneEventFilter (QGraphicsItem *filterItem)
 Removes an event filter on this item from filterItem.
 

Additional Inherited Members

- Public Types inherited from QGraphicsItem
enum  GraphicsItemFlag {
  ItemIsMovable = 0x1 , ItemIsSelectable = 0x2 , ItemIsFocusable = 0x4 , ItemClipsToShape = 0x8 ,
  ItemClipsChildrenToShape = 0x10 , ItemIgnoresTransformations = 0x20 , ItemIgnoresParentOpacity = 0x40 , ItemDoesntPropagateOpacityToChildren = 0x80 ,
  ItemStacksBehindParent = 0x100 , ItemUsesExtendedStyleOption = 0x200 , ItemHasNoContents = 0x400 , ItemSendsGeometryChanges = 0x800 ,
  ItemAcceptsInputMethod = 0x1000 , ItemNegativeZStacksBehindParent = 0x2000 , ItemIsPanel = 0x4000 , ItemIsFocusScope = 0x8000 ,
  ItemSendsScenePositionChanges = 0x10000 , ItemStopsClickFocusPropagation = 0x20000 , ItemStopsFocusHandling = 0x40000 , ItemContainsChildrenInShape = 0x80000
}
 This enum describes different flags that you can set on an item to toggle different features in the item's behavior. More...
 
enum  GraphicsItemChange {
  ItemPositionChange , ItemVisibleChange = 2 , ItemEnabledChange , ItemSelectedChange ,
  ItemParentChange , ItemChildAddedChange , ItemChildRemovedChange , ItemTransformChange ,
  ItemPositionHasChanged , ItemTransformHasChanged , ItemSceneChange , ItemVisibleHasChanged ,
  ItemEnabledHasChanged , ItemSelectedHasChanged , ItemParentHasChanged , ItemSceneHasChanged ,
  ItemCursorChange , ItemCursorHasChanged , ItemToolTipChange , ItemToolTipHasChanged ,
  ItemFlagsChange , ItemFlagsHaveChanged , ItemZValueChange , ItemZValueHasChanged ,
  ItemOpacityChange , ItemOpacityHasChanged , ItemScenePositionHasChanged , ItemRotationChange ,
  ItemRotationHasChanged , ItemScaleChange , ItemScaleHasChanged , ItemTransformOriginPointChange ,
  ItemTransformOriginPointHasChanged
}
 This enum describes the state changes that are notified by QGraphicsItem::itemChange(). More...
 
enum  CacheMode { NoCache , ItemCoordinateCache , DeviceCoordinateCache }
 
enum  PanelModality { NonModal , PanelModal , SceneModal }
 
enum  { Type = 1 , UserType = 65536 }
 
- Protected Types inherited from QGraphicsItem
enum  Extension { UserExtension = 0x80000000 }
 
- Protected Member Functions inherited from QGraphicsItem
void updateMicroFocus ()
 Updates the item's micro focus.
 
virtual bool sceneEventFilter (QGraphicsItem *watched, QEvent *event)
 Filters events for the item watched.
 
virtual bool sceneEvent (QEvent *event)
 This virtual function receives events to this item.
 
virtual void contextMenuEvent (QGraphicsSceneContextMenuEvent *event)
 This event handler can be reimplemented in a subclass to process context menu events.
 
virtual void dragEnterEvent (QGraphicsSceneDragDropEvent *event)
 This event handler, for event event, can be reimplemented to receive drag enter events for this item.
 
virtual void dragLeaveEvent (QGraphicsSceneDragDropEvent *event)
 This event handler, for event event, can be reimplemented to receive drag leave events for this item.
 
virtual void dragMoveEvent (QGraphicsSceneDragDropEvent *event)
 This event handler, for event event, can be reimplemented to receive drag move events for this item.
 
virtual void dropEvent (QGraphicsSceneDragDropEvent *event)
 This event handler, for event event, can be reimplemented to receive drop events for this item.
 
virtual void focusInEvent (QFocusEvent *event)
 This event handler, for event event, can be reimplemented to receive focus in events for this item.
 
virtual void focusOutEvent (QFocusEvent *event)
 This event handler, for event event, can be reimplemented to receive focus out events for this item.
 
virtual void hoverEnterEvent (QGraphicsSceneHoverEvent *event)
 This event handler, for event event, can be reimplemented to receive hover enter events for this item.
 
virtual void hoverMoveEvent (QGraphicsSceneHoverEvent *event)
 This event handler, for event event, can be reimplemented to receive hover move events for this item.
 
virtual void hoverLeaveEvent (QGraphicsSceneHoverEvent *event)
 This event handler, for event event, can be reimplemented to receive hover leave events for this item.
 
virtual void keyPressEvent (QKeyEvent *event)
 This event handler, for event event, can be reimplemented to receive key press events for this item.
 
virtual void keyReleaseEvent (QKeyEvent *event)
 This event handler, for event event, can be reimplemented to receive key release events for this item.
 
virtual void mousePressEvent (QGraphicsSceneMouseEvent *event)
 This event handler, for event event, can be reimplemented to receive mouse press events for this item.
 
virtual void mouseMoveEvent (QGraphicsSceneMouseEvent *event)
 This event handler, for event event, can be reimplemented to receive mouse move events for this item.
 
virtual void mouseReleaseEvent (QGraphicsSceneMouseEvent *event)
 This event handler, for event event, can be reimplemented to receive mouse release events for this item.
 
virtual void mouseDoubleClickEvent (QGraphicsSceneMouseEvent *event)
 This event handler, for event event, can be reimplemented to receive mouse double-click events for this item.
 
virtual void wheelEvent (QGraphicsSceneWheelEvent *event)
 This event handler, for event event, can be reimplemented to receive wheel events for this item.
 
virtual void inputMethodEvent (QInputMethodEvent *event)
 This event handler, for event event, can be reimplemented to receive input method events for this item.
 
virtual QVariant inputMethodQuery (Qt::InputMethodQuery query) const
 This method is only relevant for input items.
 
virtual QVariant itemChange (GraphicsItemChange change, const QVariant &value)
 This virtual function is called by QGraphicsItem to notify custom items that some part of the item's state changes.
 
virtual bool supportsExtension (Extension extension) const
 
virtual void setExtension (Extension extension, const QVariant &variant)
 
virtual QVariant extension (const QVariant &variant) const
 
 QGraphicsItem (QGraphicsItemPrivate &dd, QGraphicsItem *parent)
 
void addToIndex ()
 
void removeFromIndex ()
 
void prepareGeometryChange ()
 Prepares the item for a geometry change.
 
- Protected Attributes inherited from QGraphicsItem
QScopedPointer< QGraphicsItemPrivate > d_ptr
 
- Related Symbols inherited from QGraphicsItem
 

Detailed Description

[0]

Definition at line 5 of file src_gui_graphicsview_qgraphicsitem.cpp.

Member Function Documentation

◆ boundingRect()

QRectF SimpleItem::boundingRect ( ) const
inlineoverridevirtual

This pure virtual function defines the outer bounds of the item as a rectangle; all painting must be restricted to inside an item's bounding rect.

QGraphicsView uses this to determine whether the item requires redrawing.

Although the item's shape can be arbitrary, the bounding rect is always rectangular, and it is unaffected by the items' transformation.

If you want to change the item's bounding rectangle, you must first call prepareGeometryChange(). This notifies the scene of the imminent change, so that it can update its item geometry index; otherwise, the scene will be unaware of the item's new geometry, and the results are undefined (typically, rendering artifacts are left within the view).

Reimplement this function to let QGraphicsView determine what parts of the widget, if any, need to be redrawn.

Note: For shapes that paint an outline / stroke, it is important to include half the pen width in the bounding rect. It is not necessary to compensate for antialiasing, though.

Example:

QRectF CircleItem::boundingRect() const
{
qreal penWidth = 1;
return QRectF(-radius - penWidth / 2, -radius - penWidth / 2,
diameter + penWidth, diameter + penWidth);
}
See also
boundingRegion(), shape(), contains(), {The Graphics View Coordinate System}, prepareGeometryChange()

Implements QGraphicsItem.

Definition at line 8 of file src_gui_graphicsview_qgraphicsitem.cpp.

◆ paint()

void SimpleItem::paint ( QPainter * painter,
const QStyleOptionGraphicsItem * option,
QWidget * widget )
inlineoverridevirtual

This function, which is usually called by QGraphicsView, paints the contents of an item in local coordinates.

Reimplement this function in a QGraphicsItem subclass to provide the item's painting implementation, using painter. The option parameter provides style options for the item, such as its state, exposed area and its level-of-detail hints. The widget argument is optional. If provided, it points to the widget that is being painted on; otherwise, it is 0. For cached painting, widget is always 0.

void RoundRectItem::paint(QPainter *painter,
const QStyleOptionGraphicsItem *option,
QWidget *widget)
{
painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
}

The painter's pen is 0-width by default, and its pen is initialized to the QPalette::Text brush from the paint device's palette. The brush is initialized to QPalette::Window.

Make sure to constrain all painting inside the boundaries of boundingRect() to avoid rendering artifacts (as QGraphicsView does not clip the painter for you). In particular, when QPainter renders the outline of a shape using an assigned QPen, half of the outline will be drawn outside, and half inside, the shape you're rendering (e.g., with a pen width of 2 units, you must draw outlines 1 unit inside boundingRect()). QGraphicsItem does not support use of cosmetic pens with a non-zero width.

All painting is done in local coordinates.

Note
It is mandatory that an item will always redraw itself in the exact same way, unless update() was called; otherwise visual artifacts may occur. In other words, two subsequent calls to paint() must always produce the same output, unless update() was called between them.
Enabling caching for an item does not guarantee that paint() will be invoked only once by the Graphics View framework, even without any explicit call to update(). See the documentation of setCacheMode() for more details.
See also
setCacheMode(), QPen::width(), {Item Coordinates}, ItemUsesExtendedStyleOption

Implements QGraphicsItem.

Definition at line 15 of file src_gui_graphicsview_qgraphicsitem.cpp.

References QPainter::drawRoundedRect(), and painter.

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