com.trolltech.qt.gui
Class QGraphicsView

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.gui.QWidget
                      extended by com.trolltech.qt.gui.QFrame
                          extended by com.trolltech.qt.gui.QAbstractScrollArea
                              extended by com.trolltech.qt.gui.QGraphicsView
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface

public class QGraphicsView
extends QAbstractScrollArea

The QGraphicsView class provides a widget for displaying the contents of a QGraphicsScene. QGraphicsView visualizes the contents of a QGraphicsScene in a scrollable viewport. To create a scene with geometrical items, see QGraphicsScene's documentation. QGraphicsView is part of The Graphics View Framework.

To visualize a scene, you start by constructing a QGraphicsView object, passing the address of the scene you want to visualize to QGraphicsView's constructor. Alternatively, you can call setScene() to set the scene at a later point. After you call show(), the view will by default scroll to the center of the scene and display any items that are visible at this point. For example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addText("Hello, world!");

        QGraphicsView view = new QGraphicsView(scene);
        view.show();
You can explicitly scroll to any position on the scene by using the scroll bars, or by calling centerOn(). By passing a point to centerOn(), QGraphicsView will scroll its viewport to ensure that the point is centered in the view. An overload is provided for scrolling to a QGraphicsItem, in which case QGraphicsView will see to that the center of the item is centered in the view. If all you want is to ensure that a certain area is visible, (but not necessarily centered,) you can call ensureVisible() instead.

QGraphicsView can be used to visualize a whole scene, or only parts of it. The visualized area is by default detected automatically when the view is displayed for the first time (by calling QGraphicsScene::itemsBoundingRect()). To set the visualized area rectangle yourself, you can call setSceneRect(). This will adjust the scroll bars' ranges appropriately. Note that although the scene supports a virtually unlimited size, the range of the scroll bars will never exceed the range of an integer (INT_MIN, INT_MAX). When the scene is larger than the scroll bars' values, you can choose to use translate() to navigate the scene instead.

QGraphicsView visualizes the scene by calling render(). By default, the items are drawn onto the viewport by using a regular QPainter, and using default render hints. To change the default render hints that QGraphicsView passes to QPainter when painting items, you can call setRenderHints().

By default, QGraphicsView provides a regular QWidget for the viewport widget. You can access this widget by calling viewport(), or you can replace it by calling setViewport(). To render using OpenGL, simply call setViewport(new QGLWidget). QGraphicsView takes ownership of the viewport widget.

QGraphicsView supports affine transformations, using QMatrix. You can either pass a matrix to setMatrix(), or you can call one of the convenience functions rotate(), scale(), translate() or shear(). The most two common transformations are scaling, which is used to implement zooming, and rotation. QGraphicsView keeps the center of the view fixed during a transformation.

You can interact with the items on the scene by using the mouse and keyboard. QGraphicsView translates the mouse and key events into scene events, (events that inherit QGraphicsSceneEvent,), and forward them to the visualized scene. In the end, it's the individual item that handles the events and reacts to them. For example, if you click on a selectable item, the item will typically let the scene know that it has been selected, and it will also redraw itself to display a selection rectangle. Similiary, if you click and drag the mouse to move a movable item, it's the item that handles the mouse moves and moves itself. Item interaction is enabled by default, and you can toggle it by calling setInteractive().

You can also provide your own custom scene interaction, by creating a subclass of QGraphicsView, and reimplementing the mouse and key event handlers. To simplify how you programmatically interact with items in the view, QGraphicsView provides the mapping functions mapToScene() and mapFromScene(), and the item accessors items() and itemAt(). These functions allow you to map points, rectangles, polygons and paths between view coordinates and scene coordinates, and to find items on the scene using view coordinates.


See also:
QGraphicsScene, QGraphicsItem, and QGraphicsSceneEvent.


Nested Class Summary
static class QGraphicsView.CacheMode
           
static class QGraphicsView.CacheModeFlag
          This enum describes the flags that you can set for a QGraphicsView's cache mode.
static class QGraphicsView.DragMode
          This enum describes the default action for the view when pressing and dragging the mouse over the viewport.
static class QGraphicsView.OptimizationFlag
          This enum describes flags that you can enable to improve rendering performance in QGraphicsView.
static class QGraphicsView.OptimizationFlags
           
static class QGraphicsView.ViewportAnchor
          This enums describe the possible anchors that QGraphicsView can use when the user resizes the view or when the view is transformed.
static class QGraphicsView.ViewportUpdateMode
          This enum describes how QGraphicsView updates its viewport when the scene contents change or are exposed.
 
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QFrame
QFrame.Shadow, QFrame.Shape, QFrame.StyleMask
 
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QWidget
QWidget.RenderFlag, QWidget.RenderFlags
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.gui.QWidget
customContextMenuRequested
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QGraphicsView()
          Constructs a QGraphicsView.
QGraphicsView(QGraphicsScene scene)
          Constructs a QGraphicsView and sets the visualized scene to scene.
QGraphicsView(QGraphicsScene scene, QWidget parent)
          Constructs a QGraphicsView and sets the visualized scene to scene.
QGraphicsView(QWidget parent)
          Constructs a QGraphicsView.
 
Method Summary
 Qt.Alignment alignment()
          This property holds the alignment of the scene in the view when the whole scene is visible.
 QBrush backgroundBrush()
          This property holds the background brush of the scene.
 QGraphicsView.CacheMode cacheMode()
          This property holds which parts of the view are cached.
 void centerOn(double x, double y)
          This is an overloaded member function, provided for convenience.
 void centerOn(QGraphicsItemInterface item)
          This is an overloaded member function, provided for convenience.
 void centerOn(QPointF pos)
          Scrolls the contents of the viewport to ensure that the scene coordinate pos, is centered in the view.
 QGraphicsView.DragMode dragMode()
          This property holds the behavior for dragging the mouse over the scene while the left mouse button is pressed.
protected  void drawBackground(QPainter painter, QRectF rect)
          Draws the background of the scene using painter, before any items and the foreground are drawn.
protected  void drawForeground(QPainter painter, QRectF rect)
          Draws the foreground of the scene using painter, after the background and all items are drawn.
protected  void drawItems(QPainter painter, QGraphicsItemInterface[] items, QStyleOptionGraphicsItem[] options)
          Draws the items items in the scene using painter, after the background and before the foreground are drawn.
 void ensureVisible(double x, double y, double w, double h)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(double x, double y, double w, double h, int xmargin)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(double x, double y, double w, double h, int xmargin, int ymargin)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(QGraphicsItemInterface item)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(QGraphicsItemInterface item, int xmargin)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(QGraphicsItemInterface item, int xmargin, int ymargin)
          This is an overloaded member function, provided for convenience.
 void ensureVisible(QRectF rect)
          Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin.
 void ensureVisible(QRectF rect, int xmargin)
          Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin.
 void ensureVisible(QRectF rect, int xmargin, int ymargin)
          Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin.
 void fitInView(double x, double y, double w, double h)
          This is an overloaded member function, provided for convenience.
 void fitInView(double x, double y, double w, double h, Qt.AspectRatioMode aspectRadioMode)
          This is an overloaded member function, provided for convenience.
 void fitInView(QGraphicsItemInterface item)
          This is an overloaded member function, provided for convenience.
 void fitInView(QGraphicsItemInterface item, Qt.AspectRatioMode aspectRadioMode)
          This is an overloaded member function, provided for convenience.
 void fitInView(QRectF rect)
          Scales the view matrix and scrolls the scroll bars to ensure that the scene rectangle rect fits inside the viewport.
 void fitInView(QRectF rect, Qt.AspectRatioMode aspectRadioMode)
          Scales the view matrix and scrolls the scroll bars to ensure that the scene rectangle rect fits inside the viewport.
 QBrush foregroundBrush()
          This property holds the foreground brush of the scene.
 void invalidateScene()
          Invalidates and schedules a redraw of layers inside rect.
 void invalidateScene(QRectF rect)
          Invalidates and schedules a redraw of layers inside rect.
 void invalidateScene(QRectF rect, QGraphicsScene.SceneLayer[] layers)
           
 void invalidateScene(QRectF rect, QGraphicsScene.SceneLayers layers)
          Invalidates and schedules a redraw of layers inside rect.
 boolean isInteractive()
          This property holds whether the view allowed scene interaction.
 QGraphicsItemInterface itemAt(int x, int y)
          This is an overloaded member function, provided for convenience.
 QGraphicsItemInterface itemAt(QPoint pos)
          Returns the item at position pos, which is in viewport coordinates.
 java.util.List items()
          Returns a list of all the items in the associated scene.
 java.util.List items(int x, int y)
          This function is provided for convenience.
 java.util.List items(int x, int y, int w, int h)
          This convenience function is equivalent to calling items(QRectF(x, y, w, h)).
 java.util.List items(int x, int y, int w, int h, Qt.ItemSelectionMode mode)
          This convenience function is equivalent to calling items(QRectF(x, y, w, h), mode).
 java.util.List items(QPainterPath path)
          Returns a list of all the items that are either contained by or intersect with path.
 java.util.List items(QPainterPath path, Qt.ItemSelectionMode mode)
          This is an overloaded member function, provided for convenience.
 java.util.List items(QPoint pos)
          Returns a list of all the items at the position pos in the view.
 java.util.List items(QPolygon polygon)
          Returns a list of all the items that are either contained by or intersect with polygon.
 java.util.List items(QPolygon polygon, Qt.ItemSelectionMode mode)
          This is an overloaded member function, provided for convenience.
 java.util.List items(QRect rect)
          Returns a list of all the items that are either contained by or intersect with rect.
 java.util.List items(QRect rect, Qt.ItemSelectionMode mode)
          This is an overloaded member function, provided for convenience.
 QPoint mapFromScene(double x, double y)
          This function is provided for convenience.
 QPolygon mapFromScene(double x, double y, double w, double h)
          This function is provided for convenience.
 QPainterPath mapFromScene(QPainterPath path)
          Returns the scene coordinate painter path path to a viewport coordinate painter path.
 QPoint mapFromScene(QPointF point)
          Returns the scene coordinate point to viewport coordinates.
 QPolygon mapFromScene(QPolygonF polygon)
          Returns the scene coordinate polygon polygon to a viewport coordinate polygon.
 QPolygon mapFromScene(QRectF rect)
          Returns the scene rectangle rect to a viewport coordinate polygon.
 QPointF mapToScene(int x, int y)
          This function is provided for convenience.
 QPolygonF mapToScene(int x, int y, int w, int h)
          This function is provided for convenience.
 QPainterPath mapToScene(QPainterPath path)
          Returns the viewport painter path path mapped to a scene coordinate painter path.
 QPointF mapToScene(QPoint point)
          Returns the viewport coordinate point mapped to scene coordinates.
 QPolygonF mapToScene(QPolygon polygon)
          Returns the viewport polygon polygon mapped to a scene coordinate polygon.
 QPolygonF mapToScene(QRect rect)
          Returns the viewport rectangle rect mapped to a scene coordinate polygon.
 QMatrix matrix()
          Returns the current transformation matrix for the view.
 QGraphicsView.OptimizationFlags optimizationFlags()
          This property holds flags that can be used to tune QGraphicsView's performance.
 void render(QPainter painter)
          Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter.
 void render(QPainter painter, QRectF target)
          Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter.
 void render(QPainter painter, QRectF target, QRect source)
          Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter.
 void render(QPainter painter, QRectF target, QRect source, Qt.AspectRatioMode aspectRatioMode)
          Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter.
 QPainter.RenderHints renderHints()
          This property holds the default render hints for the view.
 void resetCachedContent()
          Resets any cached content.
 void resetMatrix()
          Resets the view transformation matrix to the identity matrix.
 void resetTransform()
          Resets the view transformation to the identity matrix.
 QGraphicsView.ViewportAnchor resizeAnchor()
          This property holds how the view should position the scene when the view is resized.
 void rotate(double angle)
          Rotates the current view transformation angle degrees clockwise.
 Qt.ItemSelectionMode rubberBandSelectionMode()
          This property holds the behavior for selecting items with a rubber band selection rectangle.
 void scale(double sx, double sy)
          Scales the current view transformation by (sx, sy).
 QGraphicsScene scene()
          Returns a pointer to the scene that is currently visualized in the view.
 QRectF sceneRect()
          This property holds the area of the scene visualized by this view.
 void setAlignment(Qt.Alignment alignment)
          This property holds the alignment of the scene in the view when the whole scene is visible.
 void setAlignment(Qt.AlignmentFlag[] alignment)
           
 void setBackgroundBrush(QBrush brush)
          This property holds the background brush of the scene.
 void setCacheMode(QGraphicsView.CacheMode mode)
          This property holds which parts of the view are cached.
 void setCacheMode(QGraphicsView.CacheModeFlag[] mode)
           
 void setDragMode(QGraphicsView.DragMode mode)
          This property holds the behavior for dragging the mouse over the scene while the left mouse button is pressed.
 void setForegroundBrush(QBrush brush)
          This property holds the foreground brush of the scene.
 void setInteractive(boolean allowed)
          This property holds whether the view allowed scene interaction.
 void setMatrix(QMatrix matrix)
          Sets the view's current transformation matrix to matrix.
 void setMatrix(QMatrix matrix, boolean combine)
          Sets the view's current transformation matrix to matrix.
 void setOptimizationFlag(QGraphicsView.OptimizationFlag flag)
          Enables flag if enabled is true; otherwise disables flag.
 void setOptimizationFlag(QGraphicsView.OptimizationFlag flag, boolean enabled)
          Enables flag if enabled is true; otherwise disables flag.
 void setOptimizationFlags(QGraphicsView.OptimizationFlag[] flags)
           
 void setOptimizationFlags(QGraphicsView.OptimizationFlags flags)
          This property holds flags that can be used to tune QGraphicsView's performance.
 void setRenderHint(QPainter.RenderHint hint)
          If enabled is true, the render hint hint is enabled; otherwise it is disabled.
 void setRenderHint(QPainter.RenderHint hint, boolean enabled)
          If enabled is true, the render hint hint is enabled; otherwise it is disabled.
 void setRenderHints(QPainter.RenderHint[] hints)
           
 void setRenderHints(QPainter.RenderHints hints)
          This property holds the default render hints for the view.
 void setResizeAnchor(QGraphicsView.ViewportAnchor anchor)
          This property holds how the view should position the scene when the view is resized.
 void setRubberBandSelectionMode(Qt.ItemSelectionMode mode)
          This property holds the behavior for selecting items with a rubber band selection rectangle.
 void setScene(QGraphicsScene scene)
          Sets the current scene to scene.
 void setSceneRect(double x, double y, double w, double h)
          This property holds the area of the scene visualized by this view.
 void setSceneRect(QRectF rect)
          This property holds the area of the scene visualized by this view.
 void setTransform(QTransform matrix)
          Sets the view's current transformation matrix to matrix.
 void setTransform(QTransform matrix, boolean combine)
          Sets the view's current transformation matrix to matrix.
 void setTransformationAnchor(QGraphicsView.ViewportAnchor anchor)
          This property holds how the view should position the scene during transformations.
 void setViewportUpdateMode(QGraphicsView.ViewportUpdateMode mode)
          This property holds how the viewport should update its contents.
 void shear(double sh, double sv)
          Shears the current view transformation by (sh, sv).
 QTransform transform()
          Returns the current transformation matrix for the view.
 QGraphicsView.ViewportAnchor transformationAnchor()
          This property holds how the view should position the scene during transformations.
 void translate(double dx, double dy)
          Translates the current view transformation by (dx, dy).
 void updateScene(java.util.List rects)
          Schedules an update of the scene rectangles rects.
 void updateSceneRect(QRectF rect)
          Notifies QGraphicsView that the scene's scene rect has changed.
 QTransform viewportTransform()
          Returns a matrix that maps viewport coordinates to scene coordinates.
 QGraphicsView.ViewportUpdateMode viewportUpdateMode()
          This property holds how the viewport should update its contents.
 
Methods inherited from class com.trolltech.qt.gui.QAbstractScrollArea
addScrollBarWidget, addScrollBarWidget, cornerWidget, horizontalScrollBar, horizontalScrollBarPolicy, maximumViewportSize, scrollBarWidgets, scrollBarWidgets, scrollContentsBy, setCornerWidget, setHorizontalScrollBar, setHorizontalScrollBarPolicy, setupViewport, setVerticalScrollBar, setVerticalScrollBarPolicy, setViewport, setViewportMargins, verticalScrollBar, verticalScrollBarPolicy, viewport, viewportEvent
 
Methods inherited from class com.trolltech.qt.gui.QFrame
frameRect, frameShadow, frameShape, frameStyle, frameWidth, lineWidth, midLineWidth, setFrameRect, setFrameShadow, setFrameShape, setFrameStyle, setLineWidth, setMidLineWidth
 
Methods inherited from class com.trolltech.qt.gui.QWidget
acceptDrops, accessibleDescription, accessibleName, actionEvent, actions, activateWindow, addAction, addActions, adjustSize, autoFillBackground, backgroundRole, baseSize, changeEvent, childAt, childAt, childrenRect, childrenRegion, clearFocus, clearMask, close, closeEvent, contentsRect, contextMenuEvent, contextMenuPolicy, cursor, depth, destroy, destroy, destroy, dragEnterEvent, dragLeaveEvent, dragMoveEvent, dropEvent, effectiveWinId, ensurePolished, enterEvent, focusInEvent, focusNextChild, focusNextPrevChild, focusOutEvent, focusPolicy, focusPreviousChild, focusProxy, focusWidget, font, fontInfo, fontMetrics, foregroundRole, frameGeometry, frameSize, geometry, getContentsMargins, grabKeyboard, grabMouse, grabMouse, grabShortcut, grabShortcut, graphicsProxyWidget, hasFocus, hasMouseTracking, height, heightForWidth, heightMM, hide, hideEvent, inputContext, inputMethodEvent, inputMethodQuery, insertAction, insertActions, isActiveWindow, isAncestorOf, isEnabled, isEnabledTo, isFullScreen, isHidden, isMaximized, isMinimized, isModal, isVisible, isVisibleTo, isWindow, isWindowModified, keyboardGrabber, keyPressEvent, keyReleaseEvent, languageChange, layout, layoutDirection, leaveEvent, locale, logicalDpiX, logicalDpiY, lower, mapFrom, mapFromGlobal, mapFromParent, mapTo, mapToGlobal, mapToParent, mask, maximumHeight, maximumSize, maximumWidth, metric, minimumHeight, minimumSize, minimumSizeHint, minimumWidth, mouseDoubleClickEvent, mouseGrabber, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, move, move, moveEvent, nativeParentWidget, nextInFocusChain, normalGeometry, numColors, overrideWindowFlags, overrideWindowFlags, overrideWindowState, paintEngine, paintEvent, paintingActive, palette, parentWidget, physicalDpiX, physicalDpiY, pos, raise, rect, releaseKeyboard, releaseMouse, releaseShortcut, removeAction, render, render, render, render, render, render, render, render, render, repaint, repaint, repaint, repaint, resetInputContext, resize, resize, resizeEvent, restoreGeometry, saveGeometry, scroll, scroll, setAcceptDrops, setAccessibleDescription, setAccessibleName, setAttribute, setAttribute, setAutoFillBackground, setBackgroundRole, setBaseSize, setBaseSize, setContentsMargins, setContentsMargins, setContextMenuPolicy, setCursor, setDisabled, setEnabled, setFixedHeight, setFixedSize, setFixedSize, setFixedWidth, setFocus, setFocus, setFocusPolicy, setFocusProxy, setFont, setForegroundRole, setGeometry, setGeometry, setHidden, setInputContext, setLayout, setLayoutDirection, setLocale, setMask, setMask, setMaximumHeight, setMaximumSize, setMaximumSize, setMaximumWidth, setMinimumHeight, setMinimumSize, setMinimumSize, setMinimumWidth, setMouseTracking, setPalette, setParent, setParent, setParent, setShortcutAutoRepeat, setShortcutAutoRepeat, setShortcutEnabled, setShortcutEnabled, setSizeIncrement, setSizeIncrement, setSizePolicy, setSizePolicy, setStatusTip, setStyle, setStyleSheet, setTabOrder, setToolTip, setUpdatesEnabled, setVisible, setWhatsThis, setWindowFilePath, setWindowFlags, setWindowFlags, setWindowIcon, setWindowIconText, setWindowModality, setWindowModified, setWindowOpacity, setWindowRole, setWindowState, setWindowState, setWindowTitle, show, showEvent, showFullScreen, showMaximized, showMinimized, showNormal, size, sizeHint, sizeIncrement, sizePolicy, stackUnder, statusTip, style, styleSheet, tabletEvent, testAttribute, toolTip, underMouse, unsetCursor, unsetLayoutDirection, unsetLocale, update, update, update, update, updateGeometry, updateMicroFocus, updatesEnabled, visibleRegion, whatsThis, wheelEvent, width, widthMM, window, windowFilePath, windowFlags, windowIcon, windowIconText, windowModality, windowOpacity, windowRole, windowState, windowTitle, windowType, winId, x, y
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QGraphicsView

public QGraphicsView(QGraphicsScene scene)
Constructs a QGraphicsView and sets the visualized scene to scene. parent is passed to QWidget's constructor.


QGraphicsView

public QGraphicsView(QGraphicsScene scene,
                     QWidget parent)
Constructs a QGraphicsView and sets the visualized scene to scene. parent is passed to QWidget's constructor.


QGraphicsView

public QGraphicsView()
Constructs a QGraphicsView. parent is passed to QWidget's constructor.


QGraphicsView

public QGraphicsView(QWidget parent)
Constructs a QGraphicsView. parent is passed to QWidget's constructor.

Method Detail

alignment

public final Qt.Alignment alignment()
This property holds the alignment of the scene in the view when the whole scene is visible. If the whole scene is visible in the view, (i.e., there are no visible scroll bars,) the view's alignment will decide where the scene will be rendered in the view. For example, if the alignment is Qt::AlignCenter , which is default, the scene will be centered in the view, and if the alignment is (Qt::AlignLeft | Qt::AlignTop ), the scene will be rendered in the top-left corner of the view.


backgroundBrush

public final QBrush backgroundBrush()
This property holds the background brush of the scene. This property sets the background brush for the scene in this view. It is used to override the scene's own background, and defines the behavior of drawBackground(). To provide custom background drawing for this view, you can reimplement drawBackground() instead.

By default, this property contains a brush with the Qt::NoBrush pattern.

See also:
QGraphicsScene::backgroundBrush, and foregroundBrush.


cacheMode

public final QGraphicsView.CacheMode cacheMode()
This property holds which parts of the view are cached. QGraphicsView can cache pre-rendered content in a QPixmap, which is then drawn onto the viewport. The purpose of such caching is to speed up the total rendering time for areas that are slow to render. Texture, gradient and alpha blended backgrounds, for example, can be notibly slow to render; especially with a transformed view. The CacheBackground flag enables caching of the view's background. For example:
        QGraphicsView view = new QGraphicsView();
        view.setBackgroundBrush(new QBrush(new QImage(":/images/backgroundtile.png")));
        view.setCacheMode(QGraphicsView.CacheModeFlag.CacheBackground);
The cache is invalidated every time the view is transformed. However, when scrolling, only partial invalidation is required.

By default, nothing is cached.

See also:
resetCachedContent(), and QPixmapCache.


centerOn

public final void centerOn(QGraphicsItemInterface item)
This is an overloaded member function, provided for convenience.

Scrolls the contents of the viewport to ensure that item is centered in the view.

See also:
ensureVisible().


centerOn

public final void centerOn(QPointF pos)
Scrolls the contents of the viewport to ensure that the scene coordinate pos, is centered in the view.

Because pos is a floating point coordinate, and the scroll bars operate on integer coordinates, the centering is only an approximation.

Note: If the item is close to or outside the border, it will be visible in the view, but not centered.

See also:
ensureVisible().


centerOn

public final void centerOn(double x,
                           double y)
This is an overloaded member function, provided for convenience.

This function is provided for convenience. It's equivalent to calling centerOn(QPointF(x, y)).


dragMode

public final QGraphicsView.DragMode dragMode()
This property holds the behavior for dragging the mouse over the scene while the left mouse button is pressed. This property defines what should happen when the user clicks on the scene background and drags the mouse (e.g., scrolling the viewport contents using a pointing hand cursor, or selecting multiple items with a rubber band). The default value, NoDrag , does nothing.

This behavior only affects mouse clicks that are not handled by any item. You can define a custom behavior by creating a subclass of QGraphicsView and reimplementing mouseMoveEvent().


ensureVisible

public final void ensureVisible(QGraphicsItemInterface item,
                                int xmargin)
This is an overloaded member function, provided for convenience.

Scrolls the contents of the viewport so that the center of item item is visible, with margins specified in pixels by xmargin and ymargin. If the specified point cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(QGraphicsItemInterface item)
This is an overloaded member function, provided for convenience.

Scrolls the contents of the viewport so that the center of item item is visible, with margins specified in pixels by xmargin and ymargin. If the specified point cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(QGraphicsItemInterface item,
                                int xmargin,
                                int ymargin)
This is an overloaded member function, provided for convenience.

Scrolls the contents of the viewport so that the center of item item is visible, with margins specified in pixels by xmargin and ymargin. If the specified point cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(QRectF rect,
                                int xmargin)
Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin. If the specified rect cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(QRectF rect)
Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin. If the specified rect cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(QRectF rect,
                                int xmargin,
                                int ymargin)
Scrolls the contents of the viewport so that the scene rectangle rect is visible, with margins specified in pixels by xmargin and ymargin. If the specified rect cannot be reached, the contents are scrolled to the nearest valid position. The default value for both margins is 50 pixels.

See also:
centerOn().


ensureVisible

public final void ensureVisible(double x,
                                double y,
                                double w,
                                double h,
                                int xmargin)
This is an overloaded member function, provided for convenience.

This function is provided for convenience. It's equivalent to calling ensureVisible(QRectF(x, y, w, h), xmargin, ymargin).


ensureVisible

public final void ensureVisible(double x,
                                double y,
                                double w,
                                double h)
This is an overloaded member function, provided for convenience.

This function is provided for convenience. It's equivalent to calling ensureVisible(QRectF(x, y, w, h), xmargin, ymargin).


ensureVisible

public final void ensureVisible(double x,
                                double y,
                                double w,
                                double h,
                                int xmargin,
                                int ymargin)
This is an overloaded member function, provided for convenience.

This function is provided for convenience. It's equivalent to calling ensureVisible(QRectF(x, y, w, h), xmargin, ymargin).


fitInView

public final void fitInView(QGraphicsItemInterface item)
This is an overloaded member function, provided for convenience.

Ensures that item fits tightly inside the view, scaling the view according to aspectRatioMode.

See also:
ensureVisible(), and centerOn().


fitInView

public final void fitInView(QGraphicsItemInterface item,
                            Qt.AspectRatioMode aspectRadioMode)
This is an overloaded member function, provided for convenience.

Ensures that item fits tightly inside the view, scaling the view according to aspectRatioMode.

See also:
ensureVisible(), and centerOn().


fitInView

public final void fitInView(QRectF rect)
Scales the view matrix and scrolls the scroll bars to ensure that the scene rectangle rect fits inside the viewport. rect must be inside the scene rect; otherwise, fitInView() cannot guarantee that the whole rect is visible.

This function keeps the view's rotation, translation, or shear. The view is scaled according to aspectRatioMode. rect will be centered in the view if it does not fit tightly.

It's common to call fitInView() from inside a reimplementation of resizeEvent(), to ensure that the whole scene, or parts of the scene, scales automatically to fit the new size of the viewport as the view is resized. Note though, that calling fitInView() from inside resizeEvent() can lead to unwanted resize recursion, if the new transformation toggles the automatic state of the scrollbars. You can toggle the scrollbar policies to always on or always off to prevent this (see horizontalScrollBarPolicy() and verticalScrollBarPolicy()).

If rect is empty, or if the viewport is too small, this function will do nothing.

See also:
setMatrix(), ensureVisible(), and centerOn().


fitInView

public final void fitInView(QRectF rect,
                            Qt.AspectRatioMode aspectRadioMode)
Scales the view matrix and scrolls the scroll bars to ensure that the scene rectangle rect fits inside the viewport. rect must be inside the scene rect; otherwise, fitInView() cannot guarantee that the whole rect is visible.

This function keeps the view's rotation, translation, or shear. The view is scaled according to aspectRatioMode. rect will be centered in the view if it does not fit tightly.

It's common to call fitInView() from inside a reimplementation of resizeEvent(), to ensure that the whole scene, or parts of the scene, scales automatically to fit the new size of the viewport as the view is resized. Note though, that calling fitInView() from inside resizeEvent() can lead to unwanted resize recursion, if the new transformation toggles the automatic state of the scrollbars. You can toggle the scrollbar policies to always on or always off to prevent this (see horizontalScrollBarPolicy() and verticalScrollBarPolicy()).

If rect is empty, or if the viewport is too small, this function will do nothing.

See also:
setMatrix(), ensureVisible(), and centerOn().


fitInView

public final void fitInView(double x,
                            double y,
                            double w,
                            double h)
This is an overloaded member function, provided for convenience.

This convenience function is equivalent to calling fitInView(QRectF(x, y, w, h), aspectRatioMode).

See also:
ensureVisible(), and centerOn().


fitInView

public final void fitInView(double x,
                            double y,
                            double w,
                            double h,
                            Qt.AspectRatioMode aspectRadioMode)
This is an overloaded member function, provided for convenience.

This convenience function is equivalent to calling fitInView(QRectF(x, y, w, h), aspectRatioMode).

See also:
ensureVisible(), and centerOn().


foregroundBrush

public final QBrush foregroundBrush()
This property holds the foreground brush of the scene. This property sets the foreground brush for the scene in this view. It is used to override the scene's own foreground, and defines the behavior of drawForeground(). To provide custom foreground drawing for this view, you can reimplement drawForeground() instead.

By default, this property contains a brush with the Qt::NoBrush pattern.

See also:
QGraphicsScene::foregroundBrush, and backgroundBrush.


invalidateScene

public final void invalidateScene(QRectF rect,
                                  QGraphicsScene.SceneLayer[] layers)

invalidateScene

public final void invalidateScene(QRectF rect)
Invalidates and schedules a redraw of layers inside rect. rect is in scene coordinates. Any cached content for layers inside rect is unconditionally invalidated and redrawn.

You can call this function to notify QGraphicsView of changes to the background or the foreground of the scene. It is commonly used for scenes with tile-based backgrounds to notify changes when QGraphicsView has enabled background caching.

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

See also:
QGraphicsScene::invalidate(), and update().


invalidateScene

public final void invalidateScene()
Invalidates and schedules a redraw of layers inside rect. rect is in scene coordinates. Any cached content for layers inside rect is unconditionally invalidated and redrawn.

You can call this function to notify QGraphicsView of changes to the background or the foreground of the scene. It is commonly used for scenes with tile-based backgrounds to notify changes when QGraphicsView has enabled background caching.

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

See also:
QGraphicsScene::invalidate(), and update().


invalidateScene

public final void invalidateScene(QRectF rect,
                                  QGraphicsScene.SceneLayers layers)
Invalidates and schedules a redraw of layers inside rect. rect is in scene coordinates. Any cached content for layers inside rect is unconditionally invalidated and redrawn.

You can call this function to notify QGraphicsView of changes to the background or the foreground of the scene. It is commonly used for scenes with tile-based backgrounds to notify changes when QGraphicsView has enabled background caching.

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

See also:
QGraphicsScene::invalidate(), and update().


isInteractive

public final boolean isInteractive()
This property holds whether the view allowed scene interaction. If enabled, this view is set to allow scene interaction. Otherwise, this view will not allow interaction, and any mouse or key events are ignored (i.e., it will act as a read-only view).

By default, this property is true.


itemAt

public final QGraphicsItemInterface itemAt(QPoint pos)
Returns the item at position pos, which is in viewport coordinates. If there are several items at this position, this function returns the topmost item.

Example:

    protected void mousePressEvent(QMouseEvent event)
    {
        QGraphicsItemInterface item = itemAt(event.pos());
        if (item != null) {
            System.out.println("You clicked on item " + item);
        } else {
            System.out.println("You didn't click on an item.");
        }
    }

See also:
items().


itemAt

public final QGraphicsItemInterface itemAt(int x,
                                           int y)
This is an overloaded member function, provided for convenience.

This function is provided for convenience. It's equivalent to calling itemAt(QPoint(x, y)).


items

public final java.util.List items()
Returns a list of all the items in the associated scene.

See also:
QGraphicsScene::items().


items

public final java.util.List items(QPainterPath path)
Returns a list of all the items that are either contained by or intersect with path.


items

public final java.util.List items(QPainterPath path,
                                  Qt.ItemSelectionMode mode)
This is an overloaded member function, provided for convenience.

Returns a list of all the items that, depending on mode, are either contained by or intersect with path. path is in viewport coordinates.

The default value for mode is Qt::IntersectsItemShape ; all items whose exact shape intersects with or is contained by path are returned.

See also:
itemAt(), items(), and mapToScene().


items

public final java.util.List items(QPoint pos)
Returns a list of all the items at the position pos in the view. The items are listed in descending Z order (i.e., the first item in the list is the top-most item, and the last item is the bottom-most item). pos is in viewport coordinates.

This function is most commonly called from within mouse event handlers in a subclass in QGraphicsView. pos is in untransformed viewport coordinates, just like QMouseEvent::pos().

    protected void mousePressEvent(QMouseEvent event)
    {
        System.out.println("There are " + items(event.pos()).size()
                           + " items at position " + mapToScene(event.pos()));
    }

See also:
QGraphicsScene::items(), and QGraphicsItem::zValue().


items

public final java.util.List items(QPolygon polygon)
Returns a list of all the items that are either contained by or intersect with polygon. polygon is in viewport coordinates.


items

public final java.util.List items(QPolygon polygon,
                                  Qt.ItemSelectionMode mode)
This is an overloaded member function, provided for convenience.

Returns a list of all the items that, depending on mode, are either contained by or intersect with polygon. polygon is in viewport coordinates.

The default value for mode is Qt::IntersectsItemShape ; all items whose exact shape intersects with or is contained by polygon are returned.

See also:
itemAt(), items(), and mapToScene().


items

public final java.util.List items(QRect rect)
Returns a list of all the items that are either contained by or intersect with rect. rect is in viewport coordinates.


items

public final java.util.List items(QRect rect,
                                  Qt.ItemSelectionMode mode)
This is an overloaded member function, provided for convenience.

Returns a list of all the items that, depending on mode, are either contained by or intersect with rect. rect is in viewport coordinates.

The default value for mode is Qt::IntersectsItemShape ; all items whose exact shape intersects with or is contained by rect are returned.

See also:
itemAt(), items(), and mapToScene().


items

public final java.util.List items(int x,
                                  int y)
This function is provided for convenience. It's equivalent to calling items(QPoint(x, y)).


items

public final java.util.List items(int x,
                                  int y,
                                  int w,
                                  int h)
This convenience function is equivalent to calling items(QRectF(x, y, w, h)).


items

public final java.util.List items(int x,
                                  int y,
                                  int w,
                                  int h,
                                  Qt.ItemSelectionMode mode)
This convenience function is equivalent to calling items(QRectF(x, y, w, h), mode).


mapFromScene

public final QPainterPath mapFromScene(QPainterPath path)
Returns the scene coordinate painter path path to a viewport coordinate painter path.

See also:
mapToScene().


mapFromScene

public final QPoint mapFromScene(QPointF point)
Returns the scene coordinate point to viewport coordinates.

See also:
mapToScene().


mapFromScene

public final QPolygon mapFromScene(QPolygonF polygon)
Returns the scene coordinate polygon polygon to a viewport coordinate polygon.

See also:
mapToScene().


mapFromScene

public final QPolygon mapFromScene(QRectF rect)
Returns the scene rectangle rect to a viewport coordinate polygon.

See also:
mapToScene().


mapFromScene

public final QPoint mapFromScene(double x,
                                 double y)
This function is provided for convenience. It's equivalent to calling mapFromScene(QPointF(x, y)).


mapFromScene

public final QPolygon mapFromScene(double x,
                                   double y,
                                   double w,
                                   double h)
This function is provided for convenience. It's equivalent to calling mapFromScene(QRectF(x, y, w, h)).


mapToScene

public final QPainterPath mapToScene(QPainterPath path)
Returns the viewport painter path path mapped to a scene coordinate painter path.

See also:
mapFromScene().


mapToScene

public final QPointF mapToScene(QPoint point)
Returns the viewport coordinate point mapped to scene coordinates.

Note: It can be useful to map the whole rectangle covered by the pixel at point instead of the point itself. To do this, you can call mapToScene(QRect(point, QSize(2, 2))).

See also:
mapFromScene().


mapToScene

public final QPolygonF mapToScene(QPolygon polygon)
Returns the viewport polygon polygon mapped to a scene coordinate polygon.

See also:
mapFromScene().


mapToScene

public final QPolygonF mapToScene(QRect rect)
Returns the viewport rectangle rect mapped to a scene coordinate polygon.

See also:
mapFromScene().


mapToScene

public final QPointF mapToScene(int x,
                                int y)
This function is provided for convenience. It's equivalent to calling mapToScene(QPoint(x, y)).


mapToScene

public final QPolygonF mapToScene(int x,
                                  int y,
                                  int w,
                                  int h)
This function is provided for convenience. It's equivalent to calling mapToScene(QRect(x, y, w, h)).


matrix

public final QMatrix matrix()
Returns the current transformation matrix for the view. If no current transformation is set, the identity matrix is returned.

See also:
setMatrix(), rotate(), scale(), shear(), and translate().


optimizationFlags

public final QGraphicsView.OptimizationFlags optimizationFlags()
This property holds flags that can be used to tune QGraphicsView's performance. QGraphicsView uses clipping, extra bounding rect adjustments, and certain other aids to improve rendering quality and performance for the common case graphics scene. However, depending on the target platform, the scene, and the viewport in use, some of these operations can degrade performance.

The effect varies from flag to flag; see the OptimizationFlags documentation for details.

By default, no optimization flags are enabled.

See also:
setOptimizationFlag().


render

public final void render(QPainter painter,
                         QRectF target,
                         QRect source)
Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter. This function is useful for capturing the contents of the view onto a paint device, such as a QImage (e.g., to take a screenshot), or for printing to QPrinter. For example:
        QGraphicsScene scene = new QGraphicsScene();
        // scene.addItem(...

        QGraphicsView view = new QGraphicsView(scene);
        view.show();
        // ...

        QPrinter printer = new QPrinter(QPrinter.PrinterMode.HighResolution);
        printer.setPageSize(QPrinter.PageSize.A4);
        QPainter painter = new QPainter(printer);

        // print, fitting the viewport contents into a full page
        view.render(painter);

        // print the upper half of the viewport into the lower.
        // half of the page.
        QRect viewport = view.viewport().rect();
        view.render(painter,
                    new QRectF(0, printer.height() / 2, printer.width(), printer.height() / 2),
                    viewport.adjusted(0, 0, 0, -viewport.height() / 2)
        );

If source is a null rect, this function will use viewport()->rect() to determine what to draw. If target is a null rect, the full dimensions of painter's paint device (e.g., for a QPrinter, the page size) will be used.

The source rect contents will be transformed according to aspectRatioMode to fit into the target rect. By default, the aspect ratio is kept, and source is scaled to fit in target.

See also:
QGraphicsScene::render().


render

public final void render(QPainter painter,
                         QRectF target)
Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter. This function is useful for capturing the contents of the view onto a paint device, such as a QImage (e.g., to take a screenshot), or for printing to QPrinter. For example:
        QGraphicsScene scene = new QGraphicsScene();
        // scene.addItem(...

        QGraphicsView view = new QGraphicsView(scene);
        view.show();
        // ...

        QPrinter printer = new QPrinter(QPrinter.PrinterMode.HighResolution);
        printer.setPageSize(QPrinter.PageSize.A4);
        QPainter painter = new QPainter(printer);

        // print, fitting the viewport contents into a full page
        view.render(painter);

        // print the upper half of the viewport into the lower.
        // half of the page.
        QRect viewport = view.viewport().rect();
        view.render(painter,
                    new QRectF(0, printer.height() / 2, printer.width(), printer.height() / 2),
                    viewport.adjusted(0, 0, 0, -viewport.height() / 2)
        );

If source is a null rect, this function will use viewport()->rect() to determine what to draw. If target is a null rect, the full dimensions of painter's paint device (e.g., for a QPrinter, the page size) will be used.

The source rect contents will be transformed according to aspectRatioMode to fit into the target rect. By default, the aspect ratio is kept, and source is scaled to fit in target.

See also:
QGraphicsScene::render().


render

public final void render(QPainter painter)
Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter. This function is useful for capturing the contents of the view onto a paint device, such as a QImage (e.g., to take a screenshot), or for printing to QPrinter. For example:
        QGraphicsScene scene = new QGraphicsScene();
        // scene.addItem(...

        QGraphicsView view = new QGraphicsView(scene);
        view.show();
        // ...

        QPrinter printer = new QPrinter(QPrinter.PrinterMode.HighResolution);
        printer.setPageSize(QPrinter.PageSize.A4);
        QPainter painter = new QPainter(printer);

        // print, fitting the viewport contents into a full page
        view.render(painter);

        // print the upper half of the viewport into the lower.
        // half of the page.
        QRect viewport = view.viewport().rect();
        view.render(painter,
                    new QRectF(0, printer.height() / 2, printer.width(), printer.height() / 2),
                    viewport.adjusted(0, 0, 0, -viewport.height() / 2)
        );

If source is a null rect, this function will use viewport()->rect() to determine what to draw. If target is a null rect, the full dimensions of painter's paint device (e.g., for a QPrinter, the page size) will be used.

The source rect contents will be transformed according to aspectRatioMode to fit into the target rect. By default, the aspect ratio is kept, and source is scaled to fit in target.

See also:
QGraphicsScene::render().


render

public final void render(QPainter painter,
                         QRectF target,
                         QRect source,
                         Qt.AspectRatioMode aspectRatioMode)
Renders the source rect, which is in view coordinates, from the scene into target, which is in paint device coordinates, using painter. This function is useful for capturing the contents of the view onto a paint device, such as a QImage (e.g., to take a screenshot), or for printing to QPrinter. For example:
        QGraphicsScene scene = new QGraphicsScene();
        // scene.addItem(...

        QGraphicsView view = new QGraphicsView(scene);
        view.show();
        // ...

        QPrinter printer = new QPrinter(QPrinter.PrinterMode.HighResolution);
        printer.setPageSize(QPrinter.PageSize.A4);
        QPainter painter = new QPainter(printer);

        // print, fitting the viewport contents into a full page
        view.render(painter);

        // print the upper half of the viewport into the lower.
        // half of the page.
        QRect viewport = view.viewport().rect();
        view.render(painter,
                    new QRectF(0, printer.height() / 2, printer.width(), printer.height() / 2),
                    viewport.adjusted(0, 0, 0, -viewport.height() / 2)
        );

If source is a null rect, this function will use viewport()->rect() to determine what to draw. If target is a null rect, the full dimensions of painter's paint device (e.g., for a QPrinter, the page size) will be used.

The source rect contents will be transformed according to aspectRatioMode to fit into the target rect. By default, the aspect ratio is kept, and source is scaled to fit in target.

See also:
QGraphicsScene::render().


renderHints

public final QPainter.RenderHints renderHints()
This property holds the default render hints for the view. These hints are used to initialize QPainter before each visible item is drawn. QPainter uses render hints to toggle rendering features such as antialiasing and smooth pixmap transformation.

QPainter::TextAntialiasing is enabled by default.

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addRect(new QRectF(-10, -10, 20, 20));

        QGraphicsView view = new QGraphicsView(scene);
        view.setRenderHints(QPainter.RenderHint.Antialiasing, QPainter.RenderHint.SmoothPixmapTransform);
        view.show();


resetCachedContent

public final void resetCachedContent()
Resets any cached content. Calling this function will clear QGraphicsView's cache. If the current cache mode is CacheNone , this function does nothing.

This function is called automatically for you when the backgroundBrush or QGraphicsScene::backgroundBrush properties change; you only need to call this function if you have reimplemented QGraphicsScene::drawBackground() or QGraphicsView::drawBackground() to draw a custom background, and need to trigger a full redraw.

See also:
cacheMode().


resetMatrix

public final void resetMatrix()
Resets the view transformation matrix to the identity matrix.


resetTransform

public final void resetTransform()
Resets the view transformation to the identity matrix.

See also:
transform(), and setTransform().


resizeAnchor

public final QGraphicsView.ViewportAnchor resizeAnchor()
This property holds how the view should position the scene when the view is resized. QGraphicsView uses this property to decide how to position the scene in the viewport when the viewport widget's size changes. The default behavior, NoAnchor , leaves the scene's position unchanged during a resize; the top-left corner of the view will appear to be anchored while resizing.

Note that the effect of this property is noticeable when only a part of the scene is visible (i.e., when there are scroll bars). Otherwise, if the whole scene fits in the view, QGraphicsScene uses the view alignment to position the scene in the view.

See also:
alignment, transformationAnchor, and Qt::WNorthWestGravity .


rotate

public final void rotate(double angle)
Rotates the current view transformation angle degrees clockwise.

See also:
setMatrix(), matrix(), scale(), shear(), and translate().


rubberBandSelectionMode

public final Qt.ItemSelectionMode rubberBandSelectionMode()
This property holds the behavior for selecting items with a rubber band selection rectangle. This property defines how items are selected when using the RubberBandDrag drag mode.

The default value is Qt::IntersectsItemShape ; all items whose shape intersects with or is contained by the rubber band are selected.

See also:
dragMode, and items().


scale

public final void scale(double sx,
                        double sy)
Scales the current view transformation by (sx, sy).

See also:
setMatrix(), matrix(), rotate(), shear(), and translate().


scene

public final QGraphicsScene scene()
Returns a pointer to the scene that is currently visualized in the view. If no scene is currently visualized, 0 is returned.

See also:
setScene().


sceneRect

public final QRectF sceneRect()
This property holds the area of the scene visualized by this view. The scene rectangle defines the extent of the scene, and in the view's case, this means the area of the scene that you can navigate using the scroll bars.

If unset, or if a null QRectF is set, this property has the same value as QGraphicsScene::sceneRect, and it changes with QGraphicsScene::sceneRect. Otherwise, the view's scene rect is unaffected by the scene.

Note that, although the scene supports a virtually unlimited size, the range of the scroll bars will never exceed the range of an integer (INT_MIN, INT_MAX). When the scene is larger than the scroll bars' values, you can choose to use translate() to navigate the scene instead.

By default, this property contains a rectangle at the origin with zero width and height.

See also:
QGraphicsScene::sceneRect.


setAlignment

public final void setAlignment(Qt.AlignmentFlag[] alignment)

setAlignment

public final void setAlignment(Qt.Alignment alignment)
This property holds the alignment of the scene in the view when the whole scene is visible. If the whole scene is visible in the view, (i.e., there are no visible scroll bars,) the view's alignment will decide where the scene will be rendered in the view. For example, if the alignment is Qt::AlignCenter , which is default, the scene will be centered in the view, and if the alignment is (Qt::AlignLeft | Qt::AlignTop ), the scene will be rendered in the top-left corner of the view.


setBackgroundBrush

public final void setBackgroundBrush(QBrush brush)
This property holds the background brush of the scene. This property sets the background brush for the scene in this view. It is used to override the scene's own background, and defines the behavior of drawBackground(). To provide custom background drawing for this view, you can reimplement drawBackground() instead.

By default, this property contains a brush with the Qt::NoBrush pattern.

See also:
QGraphicsScene::backgroundBrush, and foregroundBrush.


setCacheMode

public final void setCacheMode(QGraphicsView.CacheModeFlag[] mode)

setCacheMode

public final void setCacheMode(QGraphicsView.CacheMode mode)
This property holds which parts of the view are cached. QGraphicsView can cache pre-rendered content in a QPixmap, which is then drawn onto the viewport. The purpose of such caching is to speed up the total rendering time for areas that are slow to render. Texture, gradient and alpha blended backgrounds, for example, can be notibly slow to render; especially with a transformed view. The CacheBackground flag enables caching of the view's background. For example:
        QGraphicsView view = new QGraphicsView();
        view.setBackgroundBrush(new QBrush(new QImage(":/images/backgroundtile.png")));
        view.setCacheMode(QGraphicsView.CacheModeFlag.CacheBackground);
The cache is invalidated every time the view is transformed. However, when scrolling, only partial invalidation is required.

By default, nothing is cached.

See also:
resetCachedContent(), and QPixmapCache.


setDragMode

public final void setDragMode(QGraphicsView.DragMode mode)
This property holds the behavior for dragging the mouse over the scene while the left mouse button is pressed. This property defines what should happen when the user clicks on the scene background and drags the mouse (e.g., scrolling the viewport contents using a pointing hand cursor, or selecting multiple items with a rubber band). The default value, NoDrag , does nothing.

This behavior only affects mouse clicks that are not handled by any item. You can define a custom behavior by creating a subclass of QGraphicsView and reimplementing mouseMoveEvent().


setForegroundBrush

public final void setForegroundBrush(QBrush brush)
This property holds the foreground brush of the scene. This property sets the foreground brush for the scene in this view. It is used to override the scene's own foreground, and defines the behavior of drawForeground(). To provide custom foreground drawing for this view, you can reimplement drawForeground() instead.

By default, this property contains a brush with the Qt::NoBrush pattern.

See also:
QGraphicsScene::foregroundBrush, and backgroundBrush.


setInteractive

public final void setInteractive(boolean allowed)
This property holds whether the view allowed scene interaction. If enabled, this view is set to allow scene interaction. Otherwise, this view will not allow interaction, and any mouse or key events are ignored (i.e., it will act as a read-only view).

By default, this property is true.


setMatrix

public final void setMatrix(QMatrix matrix)
Sets the view's current transformation matrix to matrix.

If combine is true, then matrix is combined with the current matrix; otherwise, matrixreplaces the current matrix. combine is false by default.

The transformation matrix tranforms the scene into view coordinates. Using the default transformation, provided by the identity matrix, one pixel in the view represents one unit in the scene (e.g., a 10x10 rectangular item is drawn using 10x10 pixels in the view). If a 2x2 scaling matrix is applied, the scene will be drawn in 1:2 (e.g., a 10x10 rectangular item is then drawn using 20x20 pixels in the view).

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addText("GraphicsView rotated clockwise");

        QGraphicsView view = new QGraphicsView(scene);
        view.rotate(90); // the text is rendered with a 90 degree clockwise rotation
        view.show();
To simplify interation with items using a transformed view, QGraphicsView provides mapTo... and mapFrom... functions that can translate between scene and view coordinates. For example, you can call mapToScene() to map a view coordinate to a floating point scene coordinate, or mapFromScene() to map from floating point scene coordinates to view coordinates.

See also:
matrix(), rotate(), scale(), shear(), and translate().


setMatrix

public final void setMatrix(QMatrix matrix,
                            boolean combine)
Sets the view's current transformation matrix to matrix.

If combine is true, then matrix is combined with the current matrix; otherwise, matrixreplaces the current matrix. combine is false by default.

The transformation matrix tranforms the scene into view coordinates. Using the default transformation, provided by the identity matrix, one pixel in the view represents one unit in the scene (e.g., a 10x10 rectangular item is drawn using 10x10 pixels in the view). If a 2x2 scaling matrix is applied, the scene will be drawn in 1:2 (e.g., a 10x10 rectangular item is then drawn using 20x20 pixels in the view).

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addText("GraphicsView rotated clockwise");

        QGraphicsView view = new QGraphicsView(scene);
        view.rotate(90); // the text is rendered with a 90 degree clockwise rotation
        view.show();
To simplify interation with items using a transformed view, QGraphicsView provides mapTo... and mapFrom... functions that can translate between scene and view coordinates. For example, you can call mapToScene() to map a view coordinate to a floating point scene coordinate, or mapFromScene() to map from floating point scene coordinates to view coordinates.

See also:
matrix(), rotate(), scale(), shear(), and translate().


setOptimizationFlag

public final void setOptimizationFlag(QGraphicsView.OptimizationFlag flag)
Enables flag if enabled is true; otherwise disables flag.

See also:
optimizationFlags.


setOptimizationFlag

public final void setOptimizationFlag(QGraphicsView.OptimizationFlag flag,
                                      boolean enabled)
Enables flag if enabled is true; otherwise disables flag.

See also:
optimizationFlags.


setOptimizationFlags

public final void setOptimizationFlags(QGraphicsView.OptimizationFlag[] flags)

setOptimizationFlags

public final void setOptimizationFlags(QGraphicsView.OptimizationFlags flags)
This property holds flags that can be used to tune QGraphicsView's performance. QGraphicsView uses clipping, extra bounding rect adjustments, and certain other aids to improve rendering quality and performance for the common case graphics scene. However, depending on the target platform, the scene, and the viewport in use, some of these operations can degrade performance.

The effect varies from flag to flag; see the OptimizationFlags documentation for details.

By default, no optimization flags are enabled.

See also:
setOptimizationFlag().


setRenderHint

public final void setRenderHint(QPainter.RenderHint hint)
If enabled is true, the render hint hint is enabled; otherwise it is disabled.

See also:
renderHints.


setRenderHint

public final void setRenderHint(QPainter.RenderHint hint,
                                boolean enabled)
If enabled is true, the render hint hint is enabled; otherwise it is disabled.

See also:
renderHints.


setRenderHints

public final void setRenderHints(QPainter.RenderHint[] hints)

setRenderHints

public final void setRenderHints(QPainter.RenderHints hints)
This property holds the default render hints for the view. These hints are used to initialize QPainter before each visible item is drawn. QPainter uses render hints to toggle rendering features such as antialiasing and smooth pixmap transformation.

QPainter::TextAntialiasing is enabled by default.

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addRect(new QRectF(-10, -10, 20, 20));

        QGraphicsView view = new QGraphicsView(scene);
        view.setRenderHints(QPainter.RenderHint.Antialiasing, QPainter.RenderHint.SmoothPixmapTransform);
        view.show();


setResizeAnchor

public final void setResizeAnchor(QGraphicsView.ViewportAnchor anchor)
This property holds how the view should position the scene when the view is resized. QGraphicsView uses this property to decide how to position the scene in the viewport when the viewport widget's size changes. The default behavior, NoAnchor , leaves the scene's position unchanged during a resize; the top-left corner of the view will appear to be anchored while resizing.

Note that the effect of this property is noticeable when only a part of the scene is visible (i.e., when there are scroll bars). Otherwise, if the whole scene fits in the view, QGraphicsScene uses the view alignment to position the scene in the view.

See also:
alignment, transformationAnchor, and Qt::WNorthWestGravity .


setRubberBandSelectionMode

public final void setRubberBandSelectionMode(Qt.ItemSelectionMode mode)
This property holds the behavior for selecting items with a rubber band selection rectangle. This property defines how items are selected when using the RubberBandDrag drag mode.

The default value is Qt::IntersectsItemShape ; all items whose shape intersects with or is contained by the rubber band are selected.

See also:
dragMode, and items().


setScene

public final void setScene(QGraphicsScene scene)
Sets the current scene to scene. If scene is already being viewed, this function does nothing.

When a scene is set on a view, the QGraphicsScene::changed() signal is automatically connected to this view's updateScene() slot, and the view's scroll bars are adjusted to fit the size of the scene.

See also:
scene().


setSceneRect

public final void setSceneRect(QRectF rect)
This property holds the area of the scene visualized by this view. The scene rectangle defines the extent of the scene, and in the view's case, this means the area of the scene that you can navigate using the scroll bars.

If unset, or if a null QRectF is set, this property has the same value as QGraphicsScene::sceneRect, and it changes with QGraphicsScene::sceneRect. Otherwise, the view's scene rect is unaffected by the scene.

Note that, although the scene supports a virtually unlimited size, the range of the scroll bars will never exceed the range of an integer (INT_MIN, INT_MAX). When the scene is larger than the scroll bars' values, you can choose to use translate() to navigate the scene instead.

By default, this property contains a rectangle at the origin with zero width and height.

See also:
QGraphicsScene::sceneRect.


setSceneRect

public final void setSceneRect(double x,
                               double y,
                               double w,
                               double h)
This property holds the area of the scene visualized by this view. The scene rectangle defines the extent of the scene, and in the view's case, this means the area of the scene that you can navigate using the scroll bars.

If unset, or if a null QRectF is set, this property has the same value as QGraphicsScene::sceneRect, and it changes with QGraphicsScene::sceneRect. Otherwise, the view's scene rect is unaffected by the scene.

Note that, although the scene supports a virtually unlimited size, the range of the scroll bars will never exceed the range of an integer (INT_MIN, INT_MAX). When the scene is larger than the scroll bars' values, you can choose to use translate() to navigate the scene instead.

By default, this property contains a rectangle at the origin with zero width and height.

See also:
QGraphicsScene::sceneRect.


setTransform

public final void setTransform(QTransform matrix)
Sets the view's current transformation matrix to matrix.

If combine is true, then matrix is combined with the current matrix; otherwise, matrixreplaces the current matrix. combine is false by default.

The transformation matrix tranforms the scene into view coordinates. Using the default transformation, provided by the identity matrix, one pixel in the view represents one unit in the scene (e.g., a 10x10 rectangular item is drawn using 10x10 pixels in the view). If a 2x2 scaling matrix is applied, the scene will be drawn in 1:2 (e.g., a 10x10 rectangular item is then drawn using 20x20 pixels in the view).

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addText("GraphicsView rotated clockwise");

        QGraphicsView view = new QGraphicsView(scene);
        view.rotate(90); // the text is rendered with a 90 degree clockwise rotation
        view.show();
To simplify interation with items using a transformed view, QGraphicsView provides mapTo... and mapFrom... functions that can translate between scene and view coordinates. For example, you can call mapToScene() to map a view coordiate to a floating point scene coordinate, or mapFromScene() to map from floating point scene coordinates to view coordinates.

See also:
transform(), rotate(), scale(), shear(), and translate().


setTransform

public final void setTransform(QTransform matrix,
                               boolean combine)
Sets the view's current transformation matrix to matrix.

If combine is true, then matrix is combined with the current matrix; otherwise, matrixreplaces the current matrix. combine is false by default.

The transformation matrix tranforms the scene into view coordinates. Using the default transformation, provided by the identity matrix, one pixel in the view represents one unit in the scene (e.g., a 10x10 rectangular item is drawn using 10x10 pixels in the view). If a 2x2 scaling matrix is applied, the scene will be drawn in 1:2 (e.g., a 10x10 rectangular item is then drawn using 20x20 pixels in the view).

Example:

        QGraphicsScene scene = new QGraphicsScene();
        scene.addText("GraphicsView rotated clockwise");

        QGraphicsView view = new QGraphicsView(scene);
        view.rotate(90); // the text is rendered with a 90 degree clockwise rotation
        view.show();
To simplify interation with items using a transformed view, QGraphicsView provides mapTo... and mapFrom... functions that can translate between scene and view coordinates. For example, you can call mapToScene() to map a view coordiate to a floating point scene coordinate, or mapFromScene() to map from floating point scene coordinates to view coordinates.

See also:
transform(), rotate(), scale(), shear(), and translate().


setTransformationAnchor

public final void setTransformationAnchor(QGraphicsView.ViewportAnchor anchor)
This property holds how the view should position the scene during transformations. QGraphicsView uses this property to decide how to position the scene in the viewport when the transformation matrix changes, and the coordinate system of the view is transformed. The default behavior, AnchorViewCenter , ensures that the scene point at the center of the view remains unchanged during transformations (e.g., when rotating, the scene will appear to rotate around the center of the view).

Note that the effect of this property is noticeable when only a part of the scene is visible (i.e., when there are scroll bars). Otherwise, if the whole scene fits in the view, QGraphicsScene uses the view alignment to position the scene in the view.

See also:
alignment, and resizeAnchor.


setViewportUpdateMode

public final void setViewportUpdateMode(QGraphicsView.ViewportUpdateMode mode)
This property holds how the viewport should update its contents. QGraphicsView uses this property to decide how to update areas of the scene that have been reexposed or changed. Usually you do not need to modify this property, but there are some cases where doing so can improve rendering performance. See the ViewportUpdateMode documentation for specific details.

The default value is MinimalViewportUpdate , where QGraphicsView will update as small an area of the viewport as possible when the contents change.

See also:
ViewportUpdateMode , and cacheMode.


shear

public final void shear(double sh,
                        double sv)
Shears the current view transformation by (sh, sv).

See also:
setMatrix(), matrix(), rotate(), scale(), and translate().


transform

public final QTransform transform()
Returns the current transformation matrix for the view. If no current transformation is set, the identity matrix is returned.

See also:
setTransform(), rotate(), scale(), shear(), and translate().


transformationAnchor

public final QGraphicsView.ViewportAnchor transformationAnchor()
This property holds how the view should position the scene during transformations. QGraphicsView uses this property to decide how to position the scene in the viewport when the transformation matrix changes, and the coordinate system of the view is transformed. The default behavior, AnchorViewCenter , ensures that the scene point at the center of the view remains unchanged during transformations (e.g., when rotating, the scene will appear to rotate around the center of the view).

Note that the effect of this property is noticeable when only a part of the scene is visible (i.e., when there are scroll bars). Otherwise, if the whole scene fits in the view, QGraphicsScene uses the view alignment to position the scene in the view.

See also:
alignment, and resizeAnchor.


translate

public final void translate(double dx,
                            double dy)
Translates the current view transformation by (dx, dy).

See also:
setMatrix(), matrix(), rotate(), and shear().


updateScene

public final void updateScene(java.util.List rects)
Schedules an update of the scene rectangles rects.

See also:
QGraphicsScene::changed() .


updateSceneRect

public final void updateSceneRect(QRectF rect)
Notifies QGraphicsView that the scene's scene rect has changed. rect is the new scene rect. If the view already has an explicitly set scene rect, this function does nothing.

See also:
sceneRect, and QGraphicsScene::sceneRectChanged() .


viewportTransform

public final QTransform viewportTransform()
Returns a matrix that maps viewport coordinates to scene coordinates.

See also:
mapToScene(), and mapFromScene().


viewportUpdateMode

public final QGraphicsView.ViewportUpdateMode viewportUpdateMode()
This property holds how the viewport should update its contents. QGraphicsView uses this property to decide how to update areas of the scene that have been reexposed or changed. Usually you do not need to modify this property, but there are some cases where doing so can improve rendering performance. See the ViewportUpdateMode documentation for specific details.

The default value is MinimalViewportUpdate , where QGraphicsView will update as small an area of the viewport as possible when the contents change.

See also:
ViewportUpdateMode , and cacheMode.


drawBackground

protected void drawBackground(QPainter painter,
                              QRectF rect)
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 this view.

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

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

The default implementation fills rect using the view's backgroundBrush. If no such brush is defined (the default), the scene's drawBackground() function is called instead.

See also:
drawForeground(), and QGraphicsScene::drawBackground().


drawForeground

protected void drawForeground(QPainter painter,
                              QRectF rect)
Draws the foreground of the scene using painter, after the background and all items are drawn. Reimplement this function to provide a custom foreground for this view.

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

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

The default implementation fills rect using the view's foregroundBrush. If no such brush is defined (the default), the scene's drawForeground() function is called instead.

See also:
drawBackground(), and QGraphicsScene::drawForeground().


drawItems

protected void drawItems(QPainter painter,
                         QGraphicsItemInterface[] items,
                         QStyleOptionGraphicsItem[] options)
Draws the items items in the scene using painter, after the background and before the foreground are drawn. numItems is the number of items in items and options in options. options is a list of styleoptions; one for each item. Reimplement this function to provide custom item drawing for this view.

The default implementation calls the scene's drawItems() function.

See also:
drawForeground(), drawBackground(), and QGraphicsScene::drawItems().