com.trolltech.qt.gui
Class QScrollArea

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
                          extended by com.trolltech.qt.gui.QScrollArea
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface

public class QScrollArea
extends QAbstractScrollArea

The QScrollArea class provides a scrolling view onto another widget.

A scroll area is used to display the contents of a child widget within a frame. If the widget exceeds the size of the frame, the view can provide scroll bars so that the entire area of the child widget can be viewed. The child widget must be specified with setWidget. For example:

    QLabel *imageLabel = new QLabel;
    QImage image("happyguy.png");
    imageLabel->setPixmap(QPixmap::fromImage(image));

    scrollArea = new QScrollArea;
    scrollArea->setBackgroundRole(QPalette::Dark);
    scrollArea->setWidget(imageLabel);

The code above creates a scroll area (shown in the images below) containing an image label. When scaling the image, the scroll area can provide the necessary scroll bars:

The scroll bars appearance depends on the currently set scroll bar policies. You can control the appearance of the scroll bars using the inherited functionality from QAbstractScrollArea.

For example, you can set the QAbstractScrollArea::horizontalScrollBarPolicy and QAbstractScrollArea::verticalScrollBarPolicy properties. Or if you want the scroll bars to adjust dynamically when the contents of the scroll area changes, you can use the horizontalScrollBar() and verticalScrollBar() functions (which enable you to access the scroll bars) and set the scroll bars' values whenever the scroll area's contents change, using the QScrollBar::setValue() function.

You can retrieve the child widget using the widget function. The view can be made to be resizable with the setWidgetResizable function. The alignment of the widget can be specified with setAlignment.

When using a scroll area to display the contents of a custom widget, it is important to ensure that the size hint of the child widget is set to a suitable value. If a standard QWidget is used for the child widget, it may be necessary to call QWidget::setMinimumSize() to ensure that the contents of the widget are shown correctly within the scroll area.

Two convenience functions ensureVisible and ensureWidgetVisible ensure a certain region of the contents is visible inside the viewport, by scrolling the contents if necessary.

For a complete example using the QScrollArea class, see the Image Viewer example. The example shows how to combine QLabel and QScrollArea to display an image.

See Also:
QAbstractScrollArea, QScrollBar, Viewer Example

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
QScrollArea()
          Equivalent to QScrollArea(0).
QScrollArea(QWidget parent)
          Constructs an empty scroll area with the given parent.
 
Method Summary
 Qt.Alignment alignment()
          Returns the alignment of the scroll area's widget.
 void ensureVisible(int x, int y)
          Equivalent to ensureVisible(x, y, 50, 50).
 void ensureVisible(int x, int y, int xmargin)
          Equivalent to ensureVisible(x, y, xmargin, 50).
 void ensureVisible(int x, int y, int xmargin, int ymargin)
          Scrolls the contents of the scroll area so that the point (x, y) is visible inside the region of the viewport with margins specified in pixels by xmargin and ymargin.
 void ensureWidgetVisible(QWidget childWidget)
          Equivalent to ensureWidgetVisible(childWidget, 50, 50).
 void ensureWidgetVisible(QWidget childWidget, int xmargin)
          Equivalent to ensureWidgetVisible(childWidget, xmargin, 50).
 void ensureWidgetVisible(QWidget childWidget, int xmargin, int ymargin)
          Scrolls the contents of the scroll area so that the childWidget of the scroll area's widget is visible inside the region of the viewport with margins specified in pixels by xmargin and ymargin.
 boolean event(QEvent arg__1)
          This function is reimplemented for internal reasons.
 boolean eventFilter(QObject arg__1, QEvent arg__2)
          This function is reimplemented for internal reasons.
protected  boolean focusNextPrevChild(boolean next)
          This function is reimplemented for internal reasons.
static QScrollArea fromNativePointer(QNativePointer nativePointer)
          This function returns the QScrollArea instance pointed to by nativePointer
protected  void resizeEvent(QResizeEvent arg__1)
          This function is reimplemented for internal reasons.
protected  void scrollContentsBy(int dx, int dy)
          This function is reimplemented for internal reasons.
 void setAlignment(Qt.Alignment arg__1)
          Sets the alignment of the scroll area's widget to arg__1.
 void setAlignment(Qt.AlignmentFlag... arg__1)
          Sets the alignment of the scroll area's widget to arg__1.
 void setWidget(QWidget widget)
          Sets the scroll area's widget.
 void setWidgetResizable(boolean resizable)
          Sets whether the scroll area should resize the view widget to resizable.
 QSize sizeHint()
          This function is reimplemented for internal reasons.
 QWidget takeWidget()
          Removes the scroll area's widget, and passes ownership of the widget to the caller.
 QWidget widget()
          Returns the scroll area's widget, or 0 if there is none.
 boolean widgetResizable()
          Returns whether the scroll area should resize the view widget.
 
Methods inherited from class com.trolltech.qt.gui.QAbstractScrollArea
addScrollBarWidget, addScrollBarWidget, contextMenuEvent, cornerWidget, dragEnterEvent, dragLeaveEvent, dragMoveEvent, dropEvent, horizontalScrollBar, horizontalScrollBarPolicy, keyPressEvent, maximumViewportSize, minimumSizeHint, mouseDoubleClickEvent, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, paintEngine, paintEvent, scrollBarWidgets, scrollBarWidgets, setCornerWidget, setHorizontalScrollBar, setHorizontalScrollBarPolicy, setupViewport, setVerticalScrollBar, setVerticalScrollBarPolicy, setViewport, setViewportMargins, verticalScrollBar, verticalScrollBarPolicy, viewport, viewportEvent, wheelEvent
 
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, 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, 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

QScrollArea

public QScrollArea()

Equivalent to QScrollArea(0).


QScrollArea

public QScrollArea(QWidget parent)

Constructs an empty scroll area with the given parent.

See Also:
setWidget
Method Detail

alignment

public final Qt.Alignment alignment()

Returns the alignment of the scroll area's widget.

By default, the widget stays rooted to the top-left corner of the scroll area.

See Also:
setAlignment

ensureVisible

public final void ensureVisible(int x,
                                int y,
                                int xmargin)

Equivalent to ensureVisible(x, y, xmargin, 50).


ensureVisible

public final void ensureVisible(int x,
                                int y)

Equivalent to ensureVisible(x, y, 50, 50).


ensureVisible

public final void ensureVisible(int x,
                                int y,
                                int xmargin,
                                int ymargin)

Scrolls the contents of the scroll area so that the point (x, y) is visible inside the region of the viewport 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.


ensureWidgetVisible

public final void ensureWidgetVisible(QWidget childWidget,
                                      int xmargin)

Equivalent to ensureWidgetVisible(childWidget, xmargin, 50).


ensureWidgetVisible

public final void ensureWidgetVisible(QWidget childWidget)

Equivalent to ensureWidgetVisible(childWidget, 50, 50).


ensureWidgetVisible

public final void ensureWidgetVisible(QWidget childWidget,
                                      int xmargin,
                                      int ymargin)

Scrolls the contents of the scroll area so that the childWidget of the scroll area's widget is visible inside the region of the viewport 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.


setAlignment

public final void setAlignment(Qt.AlignmentFlag... arg__1)

Sets the alignment of the scroll area's widget to arg__1.

By default, the widget stays rooted to the top-left corner of the scroll area.

See Also:
alignment

setAlignment

public final void setAlignment(Qt.Alignment arg__1)

Sets the alignment of the scroll area's widget to arg__1.

By default, the widget stays rooted to the top-left corner of the scroll area.

See Also:
alignment

setWidget

public final void setWidget(QWidget widget)

Sets the scroll area's widget.

The widget becomes a child of the scroll area, and will be destroyed when the scroll area is deleted or when a new widget is set.

Note that if the scroll area is visible when the widget is added, you must show() it explicitly.

See Also:
widget

setWidgetResizable

public final void setWidgetResizable(boolean resizable)

Sets whether the scroll area should resize the view widget to resizable.

If this property is set to false (the default), the scroll area honors the size of its widget. Regardless of this property, you can programmatically resize the widget using widget->resize, and the scroll area will automatically adjust itself to the new size.

If this property is set to true, the scroll area will automatically resize the widget in order to avoid scroll bars where they can be avoided, or to take advantage of extra space.

See Also:
widgetResizable

takeWidget

public final QWidget takeWidget()

Removes the scroll area's widget, and passes ownership of the widget to the caller.

See Also:
widget

widget

public final QWidget widget()

Returns the scroll area's widget, or 0 if there is none.

See Also:
setWidget

widgetResizable

public final boolean widgetResizable()

Returns whether the scroll area should resize the view widget.

If this property is set to false (the default), the scroll area honors the size of its widget. Regardless of this property, you can programmatically resize the widget using widget->resize, and the scroll area will automatically adjust itself to the new size.

If this property is set to true, the scroll area will automatically resize the widget in order to avoid scroll bars where they can be avoided, or to take advantage of extra space.

See Also:
setWidgetResizable

event

public boolean event(QEvent arg__1)

This function is reimplemented for internal reasons.

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

eventFilter

public boolean eventFilter(QObject arg__1,
                           QEvent arg__2)

This function is reimplemented for internal reasons.

Overrides:
eventFilter in class QObject
See Also:
installEventFilter

focusNextPrevChild

protected boolean focusNextPrevChild(boolean next)

This function is reimplemented for internal reasons.

Overrides:
focusNextPrevChild in class QWidget
See Also:
focusNextChild, focusPreviousChild

resizeEvent

protected void resizeEvent(QResizeEvent arg__1)

This function is reimplemented for internal reasons.

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

scrollContentsBy

protected void scrollContentsBy(int dx,
                                int dy)

This function is reimplemented for internal reasons.

Overrides:
scrollContentsBy in class QAbstractScrollArea

sizeHint

public QSize sizeHint()

This function is reimplemented for internal reasons.

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

fromNativePointer

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

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