Package org.eclipse.swt.widgets

Class Slider

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.swt.widgets.Control

org.eclipse.swt.widgets.Slider

All Implemented Interfaces:

Adaptable, Drawable

public class Slider
extends Control

Instances of this class are selectable user interface objects that represent a range of positive, numeric values.

At any given moment, a given slider will have a single 'selection' that is considered to be its value, which is constrained to be within the range of values the slider represents (that is, between its minimum and maximum values).

Typically, sliders will be made up of five areas:

1. an arrow button for decrementing the value
2. a page decrement area for decrementing the value by a larger amount
3. a thumb for modifying the value by mouse dragging
4. a page increment area for incrementing the value by a larger amount
5. an arrow button for incrementing the value

Based on their style, sliders are either HORIZONTAL (which have a left facing button for decrementing the value and a right facing button for incrementing it) or VERTICAL (which have an upward facing button for decrementing the value and a downward facing buttons for incrementing it).

On some platforms, the size of the slider's thumb can be varied relative to the magnitude of the range of values it represents (that is, relative to the difference between its maximum and minimum values). Typically, this is used to indicate some proportional value such as the ratio of the visible area of a document to the total amount of space that it would take to display it. SWT supports setting the thumb size even if the underlying platform does not, but in this case the appearance of the slider will not change.

Styles:

HORIZONTAL, VERTICAL

Events:

Selection

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

IMPORTANT: This class is not intended to be subclassed.

Since:

1.2

See Also:

• ScrollBar

Constructor Summary

Constructors

Constructor	Description
Slider(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 value.
int	getThumb()	Returns the size of the receiver's thumb relative to the difference between its maximum and minimum values.
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 value)	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 value)	Sets the maximum.
void	setMinimum(int value)	Sets the minimum value.
void	setPageIncrement(int value)	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 value)	Sets the 'selection', which is the receiver's value, to the argument which must be greater than or equal to zero.
void	setThumb(int value)	Sets the size of the receiver's thumb relative to the difference between its maximum and minimum values.
void	setValues(int selection, int minimum, int maximum, int thumb, int increment, int pageIncrement)	Sets the receiver's selection, minimum value, maximum value, thumb, increment and page increment all at once.

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

Slider

public Slider(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.

When widgetSelected is called, the event object detail field contains one of the following values: SWT.NONE - for the end of a drag. SWT.DRAG. SWT.HOME. SWT.END. SWT.ARROW_DOWN. SWT.ARROW_UP. SWT.PAGE_DOWN. SWT.PAGE_UP. widgetDefaultSelected is not called.

Parameters:

listener - the listener which should be notified when the user changes the receiver's value

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)
• SelectionEvent

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 value.

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

getThumb

public int getThumb()

Returns the size of the receiver's thumb relative to the difference between its maximum and minimum values.

Returns:

the thumb value

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 value)

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:

value - 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 value)

Sets the maximum. If this value is negative or less than or equal to the minimum, the value is ignored. If necessary, first the thumb and then the selection are adjusted to fit within the new range.

Parameters:

value - 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 value)

Sets the minimum value. If this value is negative or greater than or equal to the maximum, the value is ignored. If necessary, first the thumb and then the selection are adjusted to fit within the new range.

Parameters:

value - the new 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

setPageIncrement

public void setPageIncrement(int value)

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:

value - 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 value)

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

Parameters:

value - 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

setThumb

public void setThumb(int value)

Sets the size of the receiver's thumb relative to the difference between its maximum and minimum values. This new value will be ignored if it is less than one, and will be clamped if it exceeds the receiver's current range.

Parameters:

value - the new thumb value, which must be at least one and not larger than the size of the current range

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

setValues

public void setValues(int selection,
 int minimum,
 int maximum,
 int thumb,
 int increment,
 int pageIncrement)

Sets the receiver's selection, minimum value, maximum value, thumb, increment and page increment all at once.

Note: This is similar to setting the values individually using the appropriate methods, but may be implemented in a more efficient fashion on some platforms.

Parameters:

selection - the new selection value

minimum - the new minimum value

maximum - the new maximum value

thumb - the new thumb value

increment - the new increment value

pageIncrement - the new pageIncrement value

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.