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com.trolltech.qt.gui
Class QGraphicsRectItem

java.lang.Object
  extended by com.trolltech.qt.QSignalEmitter
      extended by com.trolltech.qt.QtJambiObject
          extended by com.trolltech.qt.gui.QAbstractGraphicsShapeItem
              extended by com.trolltech.qt.gui.QGraphicsRectItem
All Implemented Interfaces:
QGraphicsItemInterface, QtJambiInterface

public class QGraphicsRectItem
extends QAbstractGraphicsShapeItem

The QGraphicsRectItem class provides a rectangle item that you can add to a QGraphicsScene.

To set the item's rectangle, pass a QRectF to QGraphicsRectItem's constructor, or call the setRect function. The rect function returns the current rectangle.

QGraphicsRectItem uses the rectangle and the pen width to provide a reasonable implementation of boundingRect, shape, and contains. The paint function draws the rectangle using the item's associated pen and brush, which you can set by calling the setPen and setBrush functions.

See Also:
QGraphicsPathItem, QGraphicsEllipseItem, QGraphicsPolygonItem, QGraphicsTextItem, QGraphicsLineItem, QGraphicsPixmapItem, The Graphics View Framework

Nested Class Summary
static class QGraphicsRectItem.enum_1
          Press link for info on QGraphicsRectItem.enum_1
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I>
 
Constructor Summary
QGraphicsRectItem()
          Equivalent to QGraphicsRectItem(, 0).
QGraphicsRectItem(double x, double y, double w, double h)
          Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h.
QGraphicsRectItem(double x, double y, double w, double h, QGraphicsItemInterface parent)
          Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h.
QGraphicsRectItem(double x, double y, double w, double h, QGraphicsItemInterface parent, QGraphicsScene scene)
          Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h.
QGraphicsRectItem(QGraphicsItemInterface parent)
          Equivalent to QGraphicsRectItem(parent, 0).
QGraphicsRectItem(QGraphicsItemInterface parent, QGraphicsScene scene)
          Constructs a QGraphicsRectItem, using parent as the default rectangle.
QGraphicsRectItem(QRectF rect)
          Creates a new QGraphicsRectItem with the specified bounds rect.
QGraphicsRectItem(QRectF rect, QGraphicsItemInterface parent)
          Creates a new QGraphicsRectItem with the specified bounds rect and parent.
QGraphicsRectItem(QRectF rect, QGraphicsItemInterface parent, QGraphicsScene scene)
          Creates a new QGraphicsRectItem with the specified bounds rect, parent, and then adds it to scene.
 
Method Summary
 QRectF boundingRect()
          

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.

 boolean contains(QPointF point)
          

Returns true if this item contains point, which is in local coordinates; otherwise, false is returned.

 java.lang.Object extension(java.lang.Object variant)
          

static QGraphicsRectItem fromNativePointer(QNativePointer nativePointer)
          This function returns the QGraphicsRectItem instance pointed to by nativePointer
 boolean isObscuredBy(QGraphicsItemInterface item)
          

Returns true if this item's bounding rect is completely obscured by the opaque shape of item.

The base implementation maps item's opaqueArea to this item's coordinate system, and then checks if this item's boundingRect is fully contained within the mapped shape.

You can reimplement this function to provide a custom algorithm for determining whether this item is obscured by item.

 QPainterPath opaqueArea()
          

This virtual function returns a shape representing the area where this item is opaque. An area is opaque if it is filled using an opaque brush or color (i.e., not transparent).

This function is used by isObscuredBy, which is called by underlying items to determine if they are obscured by this item.

The default implementation returns an empty QPainterPath, indicating that this item is completely transparent and does not obscure any other items.

 void paint(QPainter painter, QStyleOptionGraphicsItem option, QWidget widget)
          

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

 QRectF rect()
          Returns the item's rectangle.
 void setExtension(QGraphicsItem.Extension extension, java.lang.Object variant)
          
 void setRect(double x, double y, double w, double h)
          Sets the item's rectangle to the rectangle defined by (x, y) and the given w and h.
 void setRect(QRectF rect)
          Sets the item's rectangle to be the given rect.
 QPainterPath shape()
          

Returns the shape of this item as a QPainterPath in local coordinates.

 boolean supportsExtension(QGraphicsItem.Extension extension)
          
 int type()
          

Returns the type of an item as an int.

 
Methods inherited from class com.trolltech.qt.gui.QAbstractGraphicsShapeItem
acceptDrops, acceptedMouseButtons, acceptsHoverEvents, addToIndex, advance, brush, childItems, childrenBoundingRect, clearFocus, collidesWithItem, collidesWithPath, collidingItems, contextMenuEvent, cursor, data, deviceTransform, dragEnterEvent, dragLeaveEvent, dragMoveEvent, dropEvent, ensureVisible, ensureVisible, flags, focusInEvent, focusOutEvent, group, handlesChildEvents, hasCursor, hasFocus, hide, hoverEnterEvent, hoverLeaveEvent, hoverMoveEvent, inputMethodEvent, inputMethodQuery, installSceneEventFilter, isAncestorOf, isEnabled, isObscured, isObscured, isObscured, isSelected, isVisible, itemChange, keyPressEvent, keyReleaseEvent, mapFromItem, mapFromItem, mapFromItem, mapFromItem, mapFromItem, mapFromItem, mapFromParent, mapFromParent, mapFromParent, mapFromParent, mapFromParent, mapFromParent, mapFromScene, mapFromScene, mapFromScene, mapFromScene, mapFromScene, mapFromScene, mapToItem, mapToItem, mapToItem, mapToItem, mapToItem, mapToItem, mapToParent, mapToParent, mapToParent, mapToParent, mapToParent, mapToParent, mapToScene, mapToScene, mapToScene, mapToScene, mapToScene, mapToScene, mouseDoubleClickEvent, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, moveBy, parentItem, pen, pos, prepareGeometryChange, removeFromIndex, removeSceneEventFilter, resetTransform, rotate, scale, scene, sceneBoundingRect, sceneEvent, sceneEventFilter, scenePos, sceneTransform, setAcceptDrops, setAcceptedMouseButtons, setAcceptsHoverEvents, setBrush, setCursor, setData, setEnabled, setFlag, setFlags, setFocus, setGroup, setHandlesChildEvents, setParentItem, setPen, setPos, setPos, setSelected, setToolTip, setTransform, setVisible, setZValue, shear, show, toolTip, topLevelItem, transform, translate, unsetCursor, update, update, wheelEvent, x, y, zValue
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QGraphicsRectItem

public QGraphicsRectItem(QGraphicsItemInterface parent)

Equivalent to QGraphicsRectItem(parent, 0).


QGraphicsRectItem

public QGraphicsRectItem()

Equivalent to QGraphicsRectItem(, 0).


QGraphicsRectItem

public QGraphicsRectItem(QGraphicsItemInterface parent,
                         QGraphicsScene scene)

Constructs a QGraphicsRectItem, using parent as the default rectangle. scene is passed to QAbstractGraphicsShapeItem's constructor.

See Also:
QGraphicsScene::addItem

QGraphicsRectItem

public QGraphicsRectItem(QRectF rect,
                         QGraphicsItemInterface parent)
Creates a new QGraphicsRectItem with the specified bounds rect and parent.


QGraphicsRectItem

public QGraphicsRectItem(QRectF rect)
Creates a new QGraphicsRectItem with the specified bounds rect.


QGraphicsRectItem

public QGraphicsRectItem(QRectF rect,
                         QGraphicsItemInterface parent,
                         QGraphicsScene scene)
Creates a new QGraphicsRectItem with the specified bounds rect, parent, and then adds it to scene.


QGraphicsRectItem

public QGraphicsRectItem(double x,
                         double y,
                         double w,
                         double h,
                         QGraphicsItemInterface parent)
Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h. It will have the specified parent.


QGraphicsRectItem

public QGraphicsRectItem(double x,
                         double y,
                         double w,
                         double h)
Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h.


QGraphicsRectItem

public QGraphicsRectItem(double x,
                         double y,
                         double w,
                         double h,
                         QGraphicsItemInterface parent,
                         QGraphicsScene scene)
Creates a new QGraphicsRectItem of which top-left corner is (x, y), width is w, and height is h. It will have the specified parent and scene.

Method Detail

rect

public final QRectF rect()

Returns the item's rectangle.

See Also:
setRect

setRect

public final void setRect(double x,
                          double y,
                          double w,
                          double h)

Sets the item's rectangle to the rectangle defined by (x, y) and the given w and h.

This convenience function is equivalent to calling setRect(QRectF(x, y, width, height))

See Also:
rect

setRect

public final void setRect(QRectF rect)

Sets the item's rectangle to be the given rect.

See Also:
rect

boundingRect

public QRectF boundingRect()

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 (scale, rotate, etc.).

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 its 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 around in 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);
    }

Specified by:
boundingRect in interface QGraphicsItemInterface
Specified by:
boundingRect in class QAbstractGraphicsShapeItem
See Also:
shape, contains, The Graphics View Coordinate System, prepareGeometryChange

contains

public boolean contains(QPointF point)

Returns true if this item contains point, which is in local coordinates; otherwise, false is returned. It is most often called from QGraphicsView to determine what item is under the cursor, and for that reason, the implementation of this function should be as light-weight as possible.

By default, this function calls shape, but you can reimplement it in a subclass to provide a (perhaps more efficient) implementation.

Specified by:
contains in interface QGraphicsItemInterface
Overrides:
contains in class QAbstractGraphicsShapeItem
See Also:
shape, boundingRect, collidesWithPath

extension

public java.lang.Object extension(java.lang.Object variant)

Specified by:
extension in interface QGraphicsItemInterface
Overrides:
extension in class QAbstractGraphicsShapeItem
See Also:
setExtension

isObscuredBy

public boolean isObscuredBy(QGraphicsItemInterface item)

Returns true if this item's bounding rect is completely obscured by the opaque shape of item.

The base implementation maps item's opaqueArea to this item's coordinate system, and then checks if this item's boundingRect is fully contained within the mapped shape.

You can reimplement this function to provide a custom algorithm for determining whether this item is obscured by item.

Specified by:
isObscuredBy in interface QGraphicsItemInterface
Overrides:
isObscuredBy in class QAbstractGraphicsShapeItem
See Also:
opaqueArea, isObscured

opaqueArea

public QPainterPath opaqueArea()

This virtual function returns a shape representing the area where this item is opaque. An area is opaque if it is filled using an opaque brush or color (i.e., not transparent).

This function is used by isObscuredBy, which is called by underlying items to determine if they are obscured by this item.

The default implementation returns an empty QPainterPath, indicating that this item is completely transparent and does not obscure any other items.

Specified by:
opaqueArea in interface QGraphicsItemInterface
Overrides:
opaqueArea in class QAbstractGraphicsShapeItem
See Also:
isObscuredBy, isObscured, shape

paint

public void paint(QPainter painter,
                  QStyleOptionGraphicsItem option,
                  QWidget widget)

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.

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

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.

All painting is done in local coordinates.

Specified by:
paint in interface QGraphicsItemInterface
Specified by:
paint in class QAbstractGraphicsShapeItem

setExtension

public void setExtension(QGraphicsItem.Extension extension,
                         java.lang.Object variant)

Specified by:
setExtension in interface QGraphicsItemInterface
Overrides:
setExtension in class QAbstractGraphicsShapeItem
See Also:
extension

shape

public QPainterPath shape()

Returns the shape of this item as a QPainterPath in local coordinates. The shape is used for many things, including collision detection, hit tests, and for the QGraphicsScene::items() functions.

The default implementation calls boundingRect to return a simple rectangular shape, but subclasses can reimplement this function to return a more accurate shape for non-rectangular items. For example, a round item may choose to return an elliptic shape for better collision detection. For example:

    QPainterPath RoundItem::shape() const
    {
        QPainterPath path;
        path.addEllipse(boundingRect());
        return path;
    }

This function is called by the default implementations of contains and collidesWithPath.

Specified by:
shape in interface QGraphicsItemInterface
Overrides:
shape in class QAbstractGraphicsShapeItem
See Also:
boundingRect, contains, prepareGeometryChange

supportsExtension

public boolean supportsExtension(QGraphicsItem.Extension extension)

Specified by:
supportsExtension in interface QGraphicsItemInterface
Overrides:
supportsExtension in class QAbstractGraphicsShapeItem

type

public int type()

Returns the type of an item as an int. All standard graphicsitem classes are associated with a unique value; see QGraphicsItem::Type. This type information is used by qgraphicsitem_cast() to distinguish between types.

Reimplementing this function and declaring a Type enum value equal to your custom item's type will enable use of qgraphicsitem_cast() with the item. Custom items must return a value larger than or equal to UserType (65536).

The default implementation (in QGraphicsItem) returns UserType.

Specified by:
type in interface QGraphicsItemInterface
Overrides:
type in class QAbstractGraphicsShapeItem

fromNativePointer

public static QGraphicsRectItem fromNativePointer(QNativePointer nativePointer)
This function returns the QGraphicsRectItem instance pointed to by nativePointer

Parameters:
nativePointer - the QNativePointer of which object should be returned.

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