Package org.eclipse.swt.widgets

Class Scale

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.swt.widgets.Control

org.eclipse.swt.widgets.Scale

All Implemented Interfaces:

Adaptable, Drawable

public class Scale
extends Control

Instances of the receiver represent a selectable user interface object that present a range of continuous numeric values.

Styles:

HORIZONTAL, VERTICAL

Events:

Selection

Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.

IMPORTANT: This class is intended to be subclassed only within the SWT implementation.

Since:

1.2

Constructor Summary

Constructors

Constructor	Description
Scale(Composite parent, int style)	Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

Method Summary

Modifier and Type	Method	Description
void	addSelectionListener(SelectionListener listener)	Adds the listener to the collection of listeners who will be notified when the user changes the receiver's value, by sending it one of the messages defined in the SelectionListener interface.
Point	computeSize(int wHint, int hHint, boolean changed)	Returns the preferred size of the receiver.
<T> T	getAdapter(Class<T> adapter)	Implementation of the Adaptable interface.
int	getIncrement()	Returns the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed.
int	getMaximum()	Returns the maximum value which the receiver will allow.
int	getMinimum()	Returns the minimum value which the receiver will allow.
int	getPageIncrement()	Returns the amount that the receiver's value will be modified by when the page increment/decrement areas are selected.
int	getSelection()	Returns the 'selection', which is the receiver's position.
void	removeSelectionListener(SelectionListener listener)	Removes the listener from the collection of listeners who will be notified when the user changes the receiver's value.
void	setIncrement(int increment)	Sets the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed to the argument, which must be at least one.
void	setMaximum(int maximum)	Sets the maximum value that the receiver will allow.
void	setMinimum(int minimum)	Sets the minimum value that the receiver will allow.
void	setPageIncrement(int pageIncrement)	Sets the amount that the receiver's value will be modified by when the page increment/decrement areas are selected to the argument, which must be at least one.
void	setSelection(int selection)	Sets the 'selection', which is the receiver's value, to the argument which must be greater than or equal to zero.

Methods inherited from class org.eclipse.swt.widgets.Control

addControlListener, addDragDetectListener, addFocusListener, addGestureListener, addHelpListener, addKeyListener, addMenuDetectListener, addMouseListener, addTouchListener, addTraverseListener, computeSize, forceFocus, getAccessible, getBackground, getBackgroundImage, getBorderWidth, getBounds, getCursor, getEnabled, getFont, getForeground, getLayoutData, getLocation, getMenu, getMonitor, getOrientation, getParent, getShell, getSize, getToolTipText, getTouchEnabled, getVisible, isEnabled, isFocusControl, isReparentable, isVisible, moveAbove, moveBelow, pack, pack, redraw, redraw, removeControlListener, removeDragDetectListener, removeFocusListener, removeGestureListener, removeHelpListener, removeKeyListener, removeMenuDetectListener, removeMouseListener, removeTouchListener, removeTraverseListener, requestLayout, setBackground, setBackgroundImage, setBounds, setBounds, setCursor, setData, setEnabled, setFocus, setFont, setForeground, setLayoutData, setLocation, setLocation, setMenu, setOrientation, setParent, setRedraw, setSize, setSize, setToolTipText, setTouchEnabled, setVisible, toControl, toControl, toDisplay, toDisplay, update

Methods inherited from class org.eclipse.swt.widgets.Widget

addDisposeListener, addListener, checkSubclass, checkWidget, dispose, getData, getData, getDisplay, getListeners, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, reskin, setData, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

Scale

public Scale(Composite parent,
 int style)

Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

Parameters:

parent - a composite control which will be the parent of the new instance (cannot be null)

style - the style of control to construct

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
• ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass

See Also:

• SWT.HORIZONTAL
• SWT.VERTICAL
• Widget.checkSubclass()
• Widget.getStyle()

Method Details

addSelectionListener

public void addSelectionListener(SelectionListener listener)

Adds the listener to the collection of listeners who will be notified when the user changes the receiver's value, by sending it one of the messages defined in the SelectionListener interface.

widgetSelected is called when the user changes the receiver's value. widgetDefaultSelected is not called.

Parameters:

listener - the listener which should be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

• SelectionListener
• removeSelectionListener(org.eclipse.swt.events.SelectionListener)

removeSelectionListener

public void removeSelectionListener(SelectionListener listener)

Removes the listener from the collection of listeners who will be notified when the user changes the receiver's value.

Parameters:

listener - the listener which should no longer be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

• SelectionListener
• addSelectionListener(org.eclipse.swt.events.SelectionListener)

computeSize

public Point computeSize(int wHint,
 int hHint,
 boolean changed)

Description copied from class: Control

Returns the preferred size of the receiver.

The preferred size of a control is the size that it would best be displayed at. The width hint and height hint arguments allow the caller to ask a control questions such as "Given a particular width, how high does the control need to be to show all of the contents?" To indicate that the caller does not wish to constrain a particular dimension, the constant SWT.DEFAULT is passed for the hint.

If the changed flag is true, it indicates that the receiver's contents have changed, therefore any caches that a layout manager containing the control may have been keeping need to be flushed. When the control is resized, the changed flag will be false, so layout manager caches can be retained.

Overrides:

computeSize in class Control

Parameters:

wHint - the width hint (can be SWT.DEFAULT)

hHint - the height hint (can be SWT.DEFAULT)

changed - true if the control's contents have changed, and false otherwise

Returns:

the preferred size of the control.

See Also:

• Layout
• Control.getBorderWidth()
• Control.getBounds()
• Control.getSize()
• Control.pack(boolean)
• "computeTrim, getClientArea for controls that implement them"

getIncrement

public int getIncrement()

Returns the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed.

Returns:

the increment

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getMaximum

public int getMaximum()

Returns the maximum value which the receiver will allow.

Returns:

the maximum

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getMinimum

public int getMinimum()

Returns the minimum value which the receiver will allow.

Returns:

the minimum

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getPageIncrement

public int getPageIncrement()

Returns the amount that the receiver's value will be modified by when the page increment/decrement areas are selected.

Returns:

the page increment

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getSelection

public int getSelection()

Returns the 'selection', which is the receiver's position.

Returns:

the selection

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setIncrement

public void setIncrement(int increment)

Sets the amount that the receiver's value will be modified by when the up/down (or right/left) arrows are pressed to the argument, which must be at least one.

Parameters:

increment - the new increment (must be greater than zero)

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setMaximum

public void setMaximum(int maximum)

Sets the maximum value that the receiver will allow. This new value will be ignored if it is not greater than the receiver's current minimum value. If the new maximum is applied then the receiver's selection value will be adjusted if necessary to fall within its new range.

Parameters:

maximum - the new maximum, which must be greater than the current minimum

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setMinimum

public void setMinimum(int minimum)

Sets the minimum value that the receiver will allow. This new value will be ignored if it is negative or is not less than the receiver's current maximum value. If the new minimum is applied then the receiver's selection value will be adjusted if necessary to fall within its new range.

Parameters:

minimum - the new minimum, which must be nonnegative and less than the current maximum

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setPageIncrement

public void setPageIncrement(int pageIncrement)

Sets the amount that the receiver's value will be modified by when the page increment/decrement areas are selected to the argument, which must be at least one.

Parameters:

pageIncrement - the page increment (must be greater than zero)

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setSelection

public void setSelection(int selection)

Sets the 'selection', which is the receiver's value, to the argument which must be greater than or equal to zero.

Parameters:

selection - the new selection (must be zero or greater)

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getAdapter

public <T> T getAdapter(Class<T> adapter)

Description copied from class: Widget

Implementation of the Adaptable interface.

IMPORTANT: This method is not part of the RWT public API. It is marked public only so that it can be shared within the packages provided by RWT. It should never be accessed from application code.

Specified by:

getAdapter in interface Adaptable

Overrides:

getAdapter in class Control

Parameters:

adapter - the lookup class

Returns:

an object that can be cast to the given class or null if there is no adapter associated with the given class.