Qt Jambi Home

com.trolltech.qt.gui
Class QAbstractScrollArea

java.lang.Object
  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
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface
Direct Known Subclasses:
QAbstractItemView, QGraphicsView, QMdiArea, QScrollArea, QTextEdit

public class QAbstractScrollArea
extends QFrame

The QAbstractScrollArea widget provides a scrolling area with on-demand scroll bars.

QAbstractScrollArea is a low-level abstraction of a scrolling area. The area provides a central widget called the viewport, in which the contents of the area is to be scrolled (i.e, the visible parts of the contents are rendered in the viewport).

Next to the viewport is a vertical scroll bar, and below is a horizontal scroll bar. When all of the area contents fits in the viewport, each scroll bar can be either visible or hidden depending on the scroll bar's Qt::ScrollBarPolicy. When a scroll bar is hidden, the viewport expands in order to cover all available space. When a scroll bar becomes visible again, the viewport shrinks in order to make room for the scroll bar.

It is possible to reserve a margin area around the viewport, see setViewportMargins. The feature is mostly used to place a QHeaderView widget above or beside the scrolling area. Subclasses of QAbstractScrollArea should implement margins.

When inheriting QAbstractScrollArea, you need to do the following:

With a scroll bar policy of Qt::ScrollBarAsNeeded (the default), QAbstractScrollArea shows scroll bars when they provide a non-zero scrolling range, and hides them otherwise.

The scroll bars and viewport should be updated whenever the viewport receives a resize event or the size of the contents changes. The viewport also needs to be updated when the scroll bars values change. The initial values of the scroll bars are often set when the area receives new contents.

We give a simple example, in which we have implemented a scroll area that can scroll any QWidget. We make the widget a child of the viewport; this way, we do not have to calculate which part of the widget to draw but can simply move the widget with QWidget::move(). When the area contents or the viewport size changes, we do the following:

        QSize areaSize = viewport()->size();
        QSize  widgetSize = widget->size();

        verticalScrollBar()->setPageStep(widgetSize.height());
        horizontalScrollBar()->setPageStep(widgetSize.width());
        verticalScrollBar()->setRange(0, widgetSize.height() - areaSize.height());
        horizontalScrollBar()->setRange(0, widgetSize.width() - areaSize.width());
        updateWidgetPosition();

When the scroll bars change value, we need to update the widget position, i.e., find the part of the widget that is to be drawn in the viewport:

        int hvalue = horizontalScrollBar()->value();
        int vvalue = verticalScrollBar()->value();
        QPoint topLeft = viewport()->rect().topLeft();

        widget->move(topLeft.x() - hvalue, topLeft.y() - vvalue);

In order to track scroll bar movements, reimplement the virtual function scrollContentsBy. In order to fine-tune scrolling behavior, connect to a scroll bar's QAbstractSlider::actionTriggered() signal and adjust the QAbstractSlider::sliderPosition as you wish.

For convenience, QAbstractScrollArea makes all viewport events available in the virtual viewportEvent handler. QWidget's specialized handlers are remapped to viewport events in the cases where this makes sense. The remapped specialized handlers are: paintEvent, mousePressEvent, mouseReleaseEvent, mouseDoubleClickEvent, mouseMoveEvent, wheelEvent, dragEnterEvent, dragMoveEvent, dragLeaveEvent, dropEvent, contextMenuEvent, and resizeEvent.

QScrollArea, which inherits QAbstractScrollArea, provides smooth scrolling for any QWidget (i.e., the widget is scrolled pixel by pixel). You only need to subclass QAbstractScrollArea if you need more specialized behavior. This is, for instance, true if the entire contents of the area is not suitable for being drawn on a QWidget or if you do not want smooth scrolling.

See Also:
QScrollArea

Nested Class Summary
 
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.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>
 
Field Summary
 
Fields inherited from class com.trolltech.qt.gui.QWidget
customContextMenuRequested
 
Constructor Summary
QAbstractScrollArea()
          Equivalent to QAbstractScrollArea(0).
QAbstractScrollArea(QWidget parent)
          Constructs a viewport.
 
Method Summary
 void addScrollBarWidget(QWidget widget, Qt.Alignment alignment)
          Adds widget as a scroll bar widget in the location specified by alignment.
 void addScrollBarWidget(QWidget widget, Qt.AlignmentFlag... alignment)
          Adds widget as a scroll bar widget in the location specified by alignment.
protected  void contextMenuEvent(QContextMenuEvent arg__1)
          This event handler can be reimplemented in a subclass to receive context menu events for the viewport widget.
 QWidget cornerWidget()
          Returns the widget in the corner between the two scroll bars.
protected  void dragEnterEvent(QDragEnterEvent arg__1)
          This event handler can be reimplemented in a subclass to receive drag enter events (passed in arg__1), for the viewport widget.
protected  void dragLeaveEvent(QDragLeaveEvent arg__1)
          This event handler can be reimplemented in a subclass to receive drag leave events (passed in arg__1), for the viewport widget.
protected  void dragMoveEvent(QDragMoveEvent arg__1)
          This event handler can be reimplemented in a subclass to receive drag move events (passed in arg__1), for the viewport widget.
protected  void dropEvent(QDropEvent arg__1)
          This event handler can be reimplemented in a subclass to receive drop events (passed in arg__1), for the viewport widget.
 boolean event(QEvent arg__1)
          

This is the main event handler; it handles event arg__1. You can reimplement this function in a subclass, but we recommend using one of the specialized event handlers instead.

Key press and release events are treated differently from other events. event checks for Tab and Shift+Tab and tries to move the focus appropriately. If there is no widget to move the focus to (or the key press is not Tab or Shift+Tab), event calls keyPressEvent.

Mouse and tablet event handling is also slightly special: only when the widget is enabled, event will call the specialized handlers such as mousePressEvent; otherwise it will discard the event.

This function returns true if the event was recognized, otherwise it returns false. If the recognized event was accepted (see QEvent::accepted), any further processing such as event propagation to the parent widget stops.

static QAbstractScrollArea fromNativePointer(QNativePointer nativePointer)
          This function returns the QAbstractScrollArea instance pointed to by nativePointer
 QScrollBar horizontalScrollBar()
          Returns the horizontal scroll bar.
 Qt.ScrollBarPolicy horizontalScrollBarPolicy()
          Returns the policy for the horizontal scroll bar.
protected  void keyPressEvent(QKeyEvent arg__1)
          This function is called with key event arg__1 when key presses occur.
 QSize maximumViewportSize()
          Returns the size of the viewport as if the scroll bars had no valid scrolling range.
 QSize minimumSizeHint()
          

Returns the recommended minimum size for the widget.

protected  void mouseDoubleClickEvent(QMouseEvent arg__1)
          This event handler can be reimplemented in a subclass to receive mouse double click events for the viewport widget.
protected  void mouseMoveEvent(QMouseEvent arg__1)
          This event handler can be reimplemented in a subclass to receive mouse move events for the viewport widget.
protected  void mousePressEvent(QMouseEvent arg__1)
          This event handler can be reimplemented in a subclass to receive mouse press events for the viewport widget.
protected  void mouseReleaseEvent(QMouseEvent arg__1)
          This event handler can be reimplemented in a subclass to receive mouse release events for the viewport widget.
 QPaintEngine paintEngine()
          

Returns the widget's paint engine.

protected  void paintEvent(QPaintEvent arg__1)
          This event handler can be reimplemented in a subclass to receive paint events (passed in arg__1), for the viewport widget.
protected  void resizeEvent(QResizeEvent arg__1)
          This event handler can be reimplemented in a subclass to receive resize events (passed in arg__1), for the viewport widget.
 java.util.List<QWidget> scrollBarWidgets(Qt.Alignment alignment)
          Returns a list of the currently set scroll bar widgets.
 java.util.List<QWidget> scrollBarWidgets(Qt.AlignmentFlag... alignment)
          Returns a list of the currently set scroll bar widgets.
protected  void scrollContentsBy(int dx, int dy)
          This virtual handler is called when the scroll bars are moved by dx, dy, and consequently the viewport's contents should be scrolled accordingly.
 void setCornerWidget(QWidget widget)
          Sets the widget in the corner between the two scroll bars to be widget.
 void setHorizontalScrollBar(QScrollBar scrollbar)
          Replaces the existing horizontal scroll bar with scrollbar, and sets all the former scroll bar's slider properties on the new scroll bar.
 void setHorizontalScrollBarPolicy(Qt.ScrollBarPolicy arg__1)
          Sets the policy for the horizontal scroll bar to arg__1.
protected  void setupViewport(QWidget viewport)
          This slot is called by QAbstractScrollArea after setViewport(viewport) has been called.
 void setVerticalScrollBar(QScrollBar scrollbar)
          Replaces the existing vertical scroll bar with scrollbar, and sets all the former scroll bar's slider properties on the new scroll bar.
 void setVerticalScrollBarPolicy(Qt.ScrollBarPolicy arg__1)
          Sets the policy for the vertical scroll bar to arg__1.
 void setViewport(QWidget widget)
          Sets the viewport to be the given widget.
protected  void setViewportMargins(int left, int top, int right, int bottom)
          Sets the margins around the scrolling area to left, top, right and bottom.
 QSize sizeHint()
          

Returns the recommended size for the widget.

If the value of this property is an invalid size, no size is recommended.

The default implementation of sizeHint returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.

 QScrollBar verticalScrollBar()
          Returns the vertical scroll bar.
 Qt.ScrollBarPolicy verticalScrollBarPolicy()
          Returns the policy for the vertical scroll bar.
 QWidget viewport()
          Returns the viewport widget.
protected  boolean viewportEvent(QEvent arg__1)
          The main event handler for the scrolling area (the viewport widget).
protected  void wheelEvent(QWheelEvent arg__1)
          This event handler can be reimplemented in a subclass to receive wheel events for the viewport widget.
 
Methods inherited from class com.trolltech.qt.gui.QFrame
changeEvent, drawFrame, 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, childAt, childAt, childrenRect, childrenRegion, clearFocus, clearMask, close, closeEvent, contentsRect, contextMenuPolicy, createWinId, cursor, depth, destroy, destroy, destroy, devType, ensurePolished, enterEvent, focusInEvent, focusNextChild, focusNextPrevChild, focusOutEvent, focusPolicy, focusPreviousChild, focusProxy, focusWidget, font, fontInfo, fontMetrics, foregroundRole, frameGeometry, frameSize, geometry, getContentsMargins, grabKeyboard, grabMouse, grabMouse, grabShortcut, grabShortcut, hasFocus, hasMouseTracking, height, heightForWidth, heightMM, hide, hideEvent, inputContext, inputMethodEvent, inputMethodQuery, insertAction, insertActions, isActiveWindow, isAncestorOf, isEnabled, isEnabledTo, isFullScreen, isHidden, isLeftToRight, isMaximized, isMinimized, isModal, isRightToLeft, isVisible, isVisibleTo, isWindow, isWindowModified, keyboardGrabber, keyReleaseEvent, layout, layoutDirection, leaveEvent, locale, logicalDpiX, logicalDpiY, lower, mapFrom, mapFromGlobal, mapFromParent, mapTo, mapToGlobal, mapToParent, mask, maximumHeight, maximumSize, maximumWidth, metric, minimumHeight, minimumSize, minimumWidth, mouseGrabber, move, move, moveEvent, nextInFocusChain, normalGeometry, numColors, overrideWindowFlags, overrideWindowFlags, overrideWindowState, overrideWindowState, paintingActive, palette, parentWidget, physicalDpiX, physicalDpiY, pos, raise, rect, releaseKeyboard, releaseMouse, releaseShortcut, removeAction, render, render, render, render, render, repaint, repaint, repaint, repaint, resetInputContext, resize, resize, 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, setWindowFlags, setWindowFlags, setWindowIcon, setWindowIconText, setWindowModality, setWindowModified, setWindowOpacity, setWindowRole, setWindowState, setWindowState, setWindowTitle, show, showEvent, showFullScreen, showMaximized, showMinimized, showNormal, size, sizeIncrement, sizePolicy, stackUnder, statusTip, style, styleSheet, tabletEvent, testAttribute, toolTip, underMouse, unsetCursor, unsetLayoutDirection, unsetLocale, update, update, update, update, updateGeometry, updateMicroFocus, updatesEnabled, visibleRegion, whatsThis, width, widthMM, window, windowFlags, windowIcon, windowIconText, windowModality, windowOpacity, windowRole, windowState, windowTitle, windowType, winId, x, y
 
Methods inherited from class com.trolltech.qt.core.QObject
blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread, timerEvent
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
disconnect, disconnect, signalSender
 
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

QAbstractScrollArea

public QAbstractScrollArea()

Equivalent to QAbstractScrollArea(0).


QAbstractScrollArea

public QAbstractScrollArea(QWidget parent)

Constructs a viewport.

The parent arguments is sent to the QWidget constructor.

Method Detail

addScrollBarWidget

public final void addScrollBarWidget(QWidget widget,
                                     Qt.AlignmentFlag... alignment)

Adds widget as a scroll bar widget in the location specified by alignment.

Scroll bar widgets are shown next to the horizontal or vertical scroll bar, and can be placed on either side of it. If you want the scroll bar widgets to be always visible, set the scrollBarPolicy for the corresponding scroll bar to AlwaysOn.

alignment must be one of Qt::Alignleft and Qt::AlignRight, which maps to the horizontal scroll bar, or Qt::AlignTop and Qt::AlignBottom, which maps to the vertical scroll bar.

A scroll bar widget can be removed by either re-parenting the widget or deleting it. It's also possible to hide a widget with QWidget::hide()

The scroll bar widget will be resized to fit the scroll bar geometry for the current style. The following describes the case for scroll bar widgets on the horizontal scroll bar:

The height of the widget will be set to match the height of the scroll bar. To control the width of the widget, use QWidget::setMinimumWidth and QWidget::setMaximumWidth, or implement QWidget::sizeHint() and set a horizontal size policy. If you want a square widget, call QStyle::pixelMetric(QStyle::PM_ScrollBarExtent) and set the width to this value.

See Also:
scrollBarWidgets

addScrollBarWidget

public final void addScrollBarWidget(QWidget widget,
                                     Qt.Alignment alignment)

Adds widget as a scroll bar widget in the location specified by alignment.

Scroll bar widgets are shown next to the horizontal or vertical scroll bar, and can be placed on either side of it. If you want the scroll bar widgets to be always visible, set the scrollBarPolicy for the corresponding scroll bar to AlwaysOn.

alignment must be one of Qt::Alignleft and Qt::AlignRight, which maps to the horizontal scroll bar, or Qt::AlignTop and Qt::AlignBottom, which maps to the vertical scroll bar.

A scroll bar widget can be removed by either re-parenting the widget or deleting it. It's also possible to hide a widget with QWidget::hide()

The scroll bar widget will be resized to fit the scroll bar geometry for the current style. The following describes the case for scroll bar widgets on the horizontal scroll bar:

The height of the widget will be set to match the height of the scroll bar. To control the width of the widget, use QWidget::setMinimumWidth and QWidget::setMaximumWidth, or implement QWidget::sizeHint() and set a horizontal size policy. If you want a square widget, call QStyle::pixelMetric(QStyle::PM_ScrollBarExtent) and set the width to this value.

See Also:
scrollBarWidgets

cornerWidget

public final QWidget cornerWidget()

Returns the widget in the corner between the two scroll bars.

By default, no corner widget is present.

See Also:
setCornerWidget

horizontalScrollBar

public final QScrollBar horizontalScrollBar()

Returns the horizontal scroll bar.

See Also:
setHorizontalScrollBar, horizontalScrollBarPolicy, verticalScrollBar

horizontalScrollBarPolicy

public final Qt.ScrollBarPolicy horizontalScrollBarPolicy()

Returns the policy for the horizontal scroll bar.

The default policy is Qt::ScrollBarAsNeeded.

See Also:
setHorizontalScrollBarPolicy, verticalScrollBarPolicy

maximumViewportSize

public final QSize maximumViewportSize()

Returns the size of the viewport as if the scroll bars had no valid scrolling range.


scrollBarWidgets

public final java.util.List<QWidget> scrollBarWidgets(Qt.AlignmentFlag... alignment)

Returns a list of the currently set scroll bar widgets. alignment can be any combination of the four location flags.

See Also:
addScrollBarWidget

scrollBarWidgets

public final java.util.List<QWidget> scrollBarWidgets(Qt.Alignment alignment)

Returns a list of the currently set scroll bar widgets. alignment can be any combination of the four location flags.

See Also:
addScrollBarWidget

setCornerWidget

public final void setCornerWidget(QWidget widget)

Sets the widget in the corner between the two scroll bars to be widget.

You will probably also want to set at least one of the scroll bar modes to AlwaysOn.

Passing 0 shows no widget in the corner.

Any previous corner widget is hidden.

You may call setCornerWidget with the same widget at different times.

All widgets set here will be deleted by the scroll area when it is destroyed unless you separately reparent the widget after setting some other corner widget (or 0).

Any newly set widget should have no current parent.

By default, no corner widget is present.

See Also:
cornerWidget, horizontalScrollBarPolicy, horizontalScrollBarPolicy

setHorizontalScrollBar

public final void setHorizontalScrollBar(QScrollBar scrollbar)

Replaces the existing horizontal scroll bar with scrollbar, and sets all the former scroll bar's slider properties on the new scroll bar. The former scroll bar is then deleted.

QAbstractScrollArea already provides horizontal and vertical scroll bars by default. You can call this function to replace the default horizontal scroll bar with your own custom scroll bar.

See Also:
horizontalScrollBar, setVerticalScrollBar

setHorizontalScrollBarPolicy

public final void setHorizontalScrollBarPolicy(Qt.ScrollBarPolicy arg__1)

Sets the policy for the horizontal scroll bar to arg__1.

The default policy is Qt::ScrollBarAsNeeded.

See Also:
horizontalScrollBarPolicy, verticalScrollBarPolicy

setVerticalScrollBar

public final void setVerticalScrollBar(QScrollBar scrollbar)

Replaces the existing vertical scroll bar with scrollbar, and sets all the former scroll bar's slider properties on the new scroll bar. The former scroll bar is then deleted.

QAbstractScrollArea already provides vertical and horizontal scroll bars by default. You can call this function to replace the default vertical scroll bar with your own custom scroll bar.

See Also:
verticalScrollBar, setHorizontalScrollBar

setVerticalScrollBarPolicy

public final void setVerticalScrollBarPolicy(Qt.ScrollBarPolicy arg__1)

Sets the policy for the vertical scroll bar to arg__1.

The default policy is Qt::ScrollBarAsNeeded.

See Also:
verticalScrollBarPolicy, horizontalScrollBarPolicy

setViewport

public final void setViewport(QWidget widget)

Sets the viewport to be the given widget. The QAbstractScrollArea will take ownership of the given widget.

If widget is 0, QAbstractScrollArea will assign a new QWidget instance for the viewport.

See Also:
viewport

setViewportMargins

protected final void setViewportMargins(int left,
                                        int top,
                                        int right,
                                        int bottom)

Sets the margins around the scrolling area to left, top, right and bottom. This is useful for applications such as spreadsheets with "locked" rows and columns. The marginal space is is left blank; put widgets in the unused area.

Note that this function is frequently called by QTreeView and QTableView, so margins must be implemented by QAbstractScrollArea subclasses. Also, if the subclasses are to be used in item views, they should not call this function.

By default all margins are zero.


setupViewport

protected void setupViewport(QWidget viewport)

This slot is called by QAbstractScrollArea after setViewport(viewport) has been called. Reimplement this function in a subclass of QAbstractScrollArea to initialize the new viewport before it is used.

See Also:
setViewport

verticalScrollBar

public final QScrollBar verticalScrollBar()

Returns the vertical scroll bar.

See Also:
setVerticalScrollBar, verticalScrollBarPolicy, horizontalScrollBar

verticalScrollBarPolicy

public final Qt.ScrollBarPolicy verticalScrollBarPolicy()

Returns the policy for the vertical scroll bar.

The default policy is Qt::ScrollBarAsNeeded.

See Also:
setVerticalScrollBarPolicy, horizontalScrollBarPolicy

viewport

public final QWidget viewport()

Returns the viewport widget.

Use the QScrollArea::widget() function to retrieve the contents of the viewport widget.

See Also:
setViewport, QScrollArea::widget

contextMenuEvent

protected void contextMenuEvent(QContextMenuEvent arg__1)

This event handler can be reimplemented in a subclass to receive context menu events for the viewport widget. The event is passed in arg__1.

Overrides:
contextMenuEvent in class QWidget
See Also:
QWidget::contextMenuEvent

dragEnterEvent

protected void dragEnterEvent(QDragEnterEvent arg__1)

This event handler can be reimplemented in a subclass to receive drag enter events (passed in arg__1), for the viewport widget.

Overrides:
dragEnterEvent in class QWidget
See Also:
QWidget::dragEnterEvent

dragLeaveEvent

protected void dragLeaveEvent(QDragLeaveEvent arg__1)

This event handler can be reimplemented in a subclass to receive drag leave events (passed in arg__1), for the viewport widget.

Overrides:
dragLeaveEvent in class QWidget
See Also:
QWidget::dragLeaveEvent

dragMoveEvent

protected void dragMoveEvent(QDragMoveEvent arg__1)

This event handler can be reimplemented in a subclass to receive drag move events (passed in arg__1), for the viewport widget.

Overrides:
dragMoveEvent in class QWidget
See Also:
QWidget::dragMoveEvent

dropEvent

protected void dropEvent(QDropEvent arg__1)

This event handler can be reimplemented in a subclass to receive drop events (passed in arg__1), for the viewport widget.

Overrides:
dropEvent in class QWidget
See Also:
QWidget::dropEvent

event

public boolean event(QEvent arg__1)

This is the main event handler; it handles event arg__1. You can reimplement this function in a subclass, but we recommend using one of the specialized event handlers instead.

Key press and release events are treated differently from other events. event checks for Tab and Shift+Tab and tries to move the focus appropriately. If there is no widget to move the focus to (or the key press is not Tab or Shift+Tab), event calls keyPressEvent.

Mouse and tablet event handling is also slightly special: only when the widget is enabled, event will call the specialized handlers such as mousePressEvent; otherwise it will discard the event.

This function returns true if the event was recognized, otherwise it returns false. If the recognized event was accepted (see QEvent::accepted), any further processing such as event propagation to the parent widget stops.

Overrides:
event in class QFrame
See Also:
QEvent::type

keyPressEvent

protected void keyPressEvent(QKeyEvent arg__1)

This function is called with key event arg__1 when key presses occur. It handles PageUp, PageDown, Up, Down, Left, and Right, and ignores all other key presses.

Overrides:
keyPressEvent in class QWidget
See Also:
keyReleaseEvent, QKeyEvent::ignore, setFocusPolicy, focusInEvent, focusOutEvent, event, QKeyEvent, Tetrix Example

minimumSizeHint

public QSize minimumSizeHint()

Returns the recommended minimum size for the widget.

If the value of this property is an invalid size, no minimum size is recommended.

The default implementation of minimumSizeHint returns an invalid size if there is no layout for this widget, and returns the layout's minimum size otherwise. Most built-in widgets reimplement minimumSizeHint.

QLayout will never resize a widget to a size smaller than the minimum size hint unless minimumSize is set or the size policy is set to QSizePolicy::Ignore. If minimumSize is set, the minimum size hint will be ignored.

Overrides:
minimumSizeHint in class QWidget
See Also:
QSize::isValid, resize, setMinimumSize, sizePolicy

mouseDoubleClickEvent

protected void mouseDoubleClickEvent(QMouseEvent arg__1)

This event handler can be reimplemented in a subclass to receive mouse double click events for the viewport widget. The event is passed in arg__1.

Overrides:
mouseDoubleClickEvent in class QWidget
See Also:
QWidget::mouseDoubleClickEvent

mouseMoveEvent

protected void mouseMoveEvent(QMouseEvent arg__1)

This event handler can be reimplemented in a subclass to receive mouse move events for the viewport widget. The event is passed in arg__1.

Overrides:
mouseMoveEvent in class QWidget
See Also:
QWidget::mouseMoveEvent

mousePressEvent

protected void mousePressEvent(QMouseEvent arg__1)

This event handler can be reimplemented in a subclass to receive mouse press events for the viewport widget. The event is passed in arg__1.

Overrides:
mousePressEvent in class QWidget
See Also:
QWidget::mousePressEvent

mouseReleaseEvent

protected void mouseReleaseEvent(QMouseEvent arg__1)

This event handler can be reimplemented in a subclass to receive mouse release events for the viewport widget. The event is passed in arg__1.

Overrides:
mouseReleaseEvent in class QWidget
See Also:
QWidget::mouseReleaseEvent

paintEvent

protected void paintEvent(QPaintEvent arg__1)

This event handler can be reimplemented in a subclass to receive paint events (passed in arg__1), for the viewport widget.

Note: If you open a painter, make sure to open it on the viewport.

Overrides:
paintEvent in class QFrame
See Also:
QWidget::paintEvent

resizeEvent

protected void resizeEvent(QResizeEvent arg__1)

This event handler can be reimplemented in a subclass to receive resize events (passed in arg__1), for the viewport widget.

When resizeEvent is called, the viewport already has its new geometry: Its new size is accessible through the QResizeEvent::size() function, and the old size through QResizeEvent::oldSize().

Overrides:
resizeEvent in class QWidget
See Also:
QWidget::resizeEvent

scrollContentsBy

protected void scrollContentsBy(int dx,
                                int dy)

This virtual handler is called when the scroll bars are moved by dx, dy, and consequently the viewport's contents should be scrolled accordingly.

The default implementation simply calls update on the entire viewport, subclasses can reimplement this handler for optimization purposes, or - like QScrollArea - to move a contents widget. The parameters dx and dy are there for convenience, so that the class knows how much should be scrolled (useful e.g. when doing pixel-shifts). You may just as well ignore these values and scroll directly to the position the scroll bars indicate.

Calling this function in order to scroll programmatically is an error, use the scroll bars instead (e.g. by calling QScrollBar::setValue() directly).


sizeHint

public QSize sizeHint()

Returns the recommended size for the widget.

If the value of this property is an invalid size, no size is recommended.

The default implementation of sizeHint returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.

Overrides:
sizeHint in class QFrame
See Also:
QSize::isValid, minimumSizeHint, sizePolicy, setMinimumSize, updateGeometry

viewportEvent

protected boolean viewportEvent(QEvent arg__1)

The main event handler for the scrolling area (the viewport widget). It handles the arg__1 specified, and can be called by subclasses to provide reasonable default behavior.

Returns true to indicate to the event system that the event has been handled, and needs no further processing; otherwise returns false to indicate that the event should be propagated further.

You can reimplement this function in a subclass, but we recommend using one of the specialized event handlers instead.

Specialised handlers for viewport events are: paintEvent, mousePressEvent, mouseReleaseEvent, mouseDoubleClickEvent, mouseMoveEvent, wheelEvent, dragEnterEvent, dragMoveEvent, dragLeaveEvent, dropEvent, contextMenuEvent, and resizeEvent.


wheelEvent

protected void wheelEvent(QWheelEvent arg__1)

This event handler can be reimplemented in a subclass to receive wheel events for the viewport widget. The event is passed in arg__1.

Overrides:
wheelEvent in class QWidget
See Also:
QWidget::wheelEvent

fromNativePointer

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

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

paintEngine

public QPaintEngine paintEngine()

Returns the widget's paint engine.

Specified by:
paintEngine in interface QPaintDeviceInterface
Overrides:
paintEngine in class QWidget

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