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com.trolltech.qt.gui
Class QDial

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

public class QDial
extends QAbstractSlider

The QDial class provides a rounded range control (like a speedometer or potentiometer).

QDial is used when the user needs to control a value within a program-definable range, and the range either wraps around (for example, with angles measured from 0 to 359 degrees) or the dialog layout needs a square widget.

Since QDial inherits from QAbstractSlider, the dial behaves in a similar way to a slider. When wrapping is false (the default setting) there is no real difference between a slider and a dial. They both share the same signals, slots and member functions. Which one you use depends on the expectations of your users and on the type of application.

The dial initially emits valueChanged signals continuously while the slider is being moved; you can make it emit the signal less often by disabling the tracking property. The sliderMoved signal is emitted continuously even when tracking is disabled.

The dial also emits sliderPressed and sliderReleased signals when the mouse button is pressed and released. Note that the dial's value can change without these signals being emitted since the keyboard and wheel can also be used to change the value.

Unlike the slider, QDial attempts to draw a "nice" number of notches rather than one per line step. If possible, the number of notches drawn is one per line step, but if there aren't enough pixels to draw every one, QDial will skip notches to try and draw a uniform set (e.g. by drawing every second or third notch).

Like the slider, the dial makes the QAbstractSlider functions setValue, addLine(), subtractLine(), addPage() and subtractPage() available as slots.

The dial's keyboard interface is fairly simple: The left/up and right/down arrow keys adjust the dial's value by the defined singleStep, Page Up and Page Down by the defined pageStep, and the Home and End keys set the value to the defined minimum and maximum values.

Screenshot of a dial in the Plastique widget styleScreenshot of a dial in the Windows XP widget styleScreenshot of a dial in the Macintosh widget style
Dials shown in various widget styles (from left to right): Plastique, Windows XP, Macintosh.

See Also:
QScrollBar, QSpinBox, QSlider, GUI Design Handbook: Slider, Sliders Example

Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QAbstractSlider
QAbstractSlider.SliderAction, QAbstractSlider.SliderChange
 
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.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.QAbstractSlider
actionTriggered, rangeChanged, sliderMoved, sliderPressed, sliderReleased, valueChanged
 
Fields inherited from class com.trolltech.qt.gui.QWidget
customContextMenuRequested
 
Constructor Summary
QDial()
          Equivalent to QDial(0).
QDial(QWidget parent)
          Constructs a dial.
 
Method Summary
 boolean event(QEvent e)
          This function is reimplemented for internal reasons.
static QDial fromNativePointer(QNativePointer nativePointer)
          This function returns the QDial instance pointed to by nativePointer
protected  void initStyleOption(QStyleOptionSlider option)
          Initialize option with the values from this QDial.
 QSize minimumSizeHint()
          This function is reimplemented for internal reasons.
protected  void mouseMoveEvent(QMouseEvent me)
          This function is reimplemented for internal reasons.
protected  void mousePressEvent(QMouseEvent me)
          This function is reimplemented for internal reasons.
protected  void mouseReleaseEvent(QMouseEvent me)
          This function is reimplemented for internal reasons.
 boolean notchesVisible()
          Returns whether the notches are shown.
 int notchSize()
          Returns the current notch size.
 double notchTarget()
          Returns the target number of pixels between notches.
protected  void paintEvent(QPaintEvent pe)
          This function is reimplemented for internal reasons.
protected  void resizeEvent(QResizeEvent re)
          This function is reimplemented for internal reasons.
 void setNotchesVisible(boolean visible)
          Sets whether the notches are shown to visible.
 void setNotchTarget(double target)
          Sets the target number of pixels between notches to target.
 void setWrapping(boolean on)
          Sets whether wrapping is enabled to on.
 QSize sizeHint()
          This function is reimplemented for internal reasons.
protected  void sliderChange(QAbstractSlider.SliderChange change)
          Reimplement this virtual function to track slider changes such as SliderRangeChange, SliderOrientationChange, SliderStepsChange, or SliderValueChange.
 boolean wrapping()
          Returns whether wrapping is enabled.
 
Methods inherited from class com.trolltech.qt.gui.QAbstractSlider
changeEvent, hasTracking, invertedAppearance, invertedControls, isSliderDown, keyPressEvent, maximum, minimum, orientation, pageStep, repeatAction, setInvertedAppearance, setInvertedControls, setMaximum, setMinimum, setOrientation, setPageStep, setRange, setRepeatAction, setRepeatAction, setRepeatAction, setSingleStep, setSliderDown, setSliderPosition, setTracking, setValue, singleStep, sliderPosition, timerEvent, triggerAction, value, wheelEvent
 
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, contextMenuEvent, contextMenuPolicy, createWinId, cursor, depth, destroy, destroy, destroy, devType, dragEnterEvent, dragLeaveEvent, dragMoveEvent, dropEvent, 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, mouseDoubleClickEvent, mouseGrabber, move, move, moveEvent, nextInFocusChain, normalGeometry, numColors, overrideWindowFlags, overrideWindowFlags, overrideWindowState, overrideWindowState, paintEngine, 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
 
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

QDial

public QDial()

Equivalent to QDial(0).


QDial

public QDial(QWidget parent)

Constructs a dial.

The parent argument is sent to the QAbstractSlider constructor.

Method Detail

notchSize

public final int notchSize()

Returns the current notch size.

The notch size is in range control units, not pixels, and if possible it is a multiple of singleStep that results in an on-screen notch size near notchTarget.

See Also:
notchTarget, singleStep

notchTarget

public final double notchTarget()

Returns the target number of pixels between notches.

The notch target is the number of pixels QDial attempts to put between each notch.

The actual size may differ from the target size.

The default notch target is 3.7 pixels.

See Also:
setNotchTarget

notchesVisible

public final boolean notchesVisible()

Returns whether the notches are shown.

If the property is true, a series of notches are drawn around the dial to indicate the range of values available; otherwise no notches are shown.

By default, this property is disabled.

See Also:
setNotchesVisible

setNotchTarget

public final void setNotchTarget(double target)

Sets the target number of pixels between notches to target.

The notch target is the number of pixels QDial attempts to put between each notch.

The actual size may differ from the target size.

The default notch target is 3.7 pixels.

See Also:
notchTarget

setNotchesVisible

public final void setNotchesVisible(boolean visible)

Sets whether the notches are shown to visible.

If the property is true, a series of notches are drawn around the dial to indicate the range of values available; otherwise no notches are shown.

By default, this property is disabled.

See Also:
notchesVisible

setWrapping

public final void setWrapping(boolean on)

Sets whether wrapping is enabled to on.

If true, wrapping is enabled; otherwise some space is inserted at the bottom of the dial to separate the ends of the range of valid values.

If enabled, the arrow can be oriented at any angle on the dial. If disabled, the arrow will be restricted to the upper part of the dial; if it is rotated into the space at the bottom of the dial, it will be clamped to the closest end of the valid range of values.

By default this property is false.

See Also:
wrapping

wrapping

public final boolean wrapping()

Returns whether wrapping is enabled.

If true, wrapping is enabled; otherwise some space is inserted at the bottom of the dial to separate the ends of the range of valid values.

If enabled, the arrow can be oriented at any angle on the dial. If disabled, the arrow will be restricted to the upper part of the dial; if it is rotated into the space at the bottom of the dial, it will be clamped to the closest end of the valid range of values.

By default this property is false.

See Also:
setWrapping

event

public boolean event(QEvent e)

This function is reimplemented for internal reasons.

Overrides:
event in class QAbstractSlider
See Also:
closeEvent, focusInEvent, focusOutEvent, enterEvent, keyPressEvent, keyReleaseEvent, leaveEvent, mouseDoubleClickEvent, mouseMoveEvent, mousePressEvent, mouseReleaseEvent, moveEvent, paintEvent, resizeEvent, QObject::event, QObject::timerEvent

minimumSizeHint

public QSize minimumSizeHint()

This function is reimplemented for internal reasons.

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

mouseMoveEvent

protected void mouseMoveEvent(QMouseEvent me)

This function is reimplemented for internal reasons.

Overrides:
mouseMoveEvent in class QWidget
See Also:
setMouseTracking, mousePressEvent, mouseReleaseEvent, mouseDoubleClickEvent, event, QMouseEvent, Example

mousePressEvent

protected void mousePressEvent(QMouseEvent me)

This function is reimplemented for internal reasons.

Overrides:
mousePressEvent in class QWidget
See Also:
mouseReleaseEvent, mouseDoubleClickEvent, mouseMoveEvent, event, QMouseEvent, Example

mouseReleaseEvent

protected void mouseReleaseEvent(QMouseEvent me)

This function is reimplemented for internal reasons.

Overrides:
mouseReleaseEvent in class QWidget
See Also:
mousePressEvent, mouseDoubleClickEvent, mouseMoveEvent, event, QMouseEvent, Example

paintEvent

protected void paintEvent(QPaintEvent pe)

This function is reimplemented for internal reasons.

Overrides:
paintEvent in class QWidget
See Also:
event, repaint, update, QPainter, QPixmap, QPaintEvent, Analog Clock Example

resizeEvent

protected void resizeEvent(QResizeEvent re)

This function is reimplemented for internal reasons.

Overrides:
resizeEvent in class QWidget
See Also:
moveEvent, event, resize, QResizeEvent, paintEvent, Example

sizeHint

public QSize sizeHint()

This function is reimplemented for internal reasons.

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

sliderChange

protected void sliderChange(QAbstractSlider.SliderChange change)

Reimplement this virtual function to track slider changes such as SliderRangeChange, SliderOrientationChange, SliderStepsChange, or SliderValueChange. The default implementation only updates the display and ignores the change parameter.

Overrides:
sliderChange in class QAbstractSlider

fromNativePointer

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

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

initStyleOption

protected final void initStyleOption(QStyleOptionSlider option)
Initialize option with the values from this QDial. This method is useful for subclasses when they need a QStyleOptionSlider, but don't want to fill in all the information themselves.


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