Eclipse Platform
Release 4.2

org.eclipse.swt.widgets
Class Slider

java.lang.Object
  extended by org.eclipse.swt.widgets.Widget
      extended by org.eclipse.swt.widgets.Control
          extended by org.eclipse.swt.widgets.Slider
All Implemented Interfaces:
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.

See Also:
ScrollBar, Slider snippets, SWT Example: ControlExample, Sample code and further information
Restriction:
This class is not intended to be subclassed by clients.

Field Summary
 
Fields inherited from class org.eclipse.swt.widgets.Control
handle
 
Constructor Summary
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
 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.
 boolean getEnabled()
          Returns true if the receiver is enabled, and false otherwise.
 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 receiver's thumb value.
 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 thumb value.
 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, addMouseMoveListener, addMouseTrackListener, addMouseWheelListener, addPaintListener, addTouchListener, addTraverseListener, computeSize, dragDetect, dragDetect, forceFocus, getAccessible, getBackground, getBackgroundImage, getBorderWidth, getBounds, getCursor, getDragDetect, getFont, getForeground, getLayoutData, getLocation, getMenu, getMonitor, getOrientation, getParent, getRegion, getShell, getSize, getToolTipText, getTouchEnabled, getVisible, internal_dispose_GC, internal_new_GC, isEnabled, isFocusControl, isReparentable, isVisible, moveAbove, moveBelow, pack, pack, print, redraw, redraw, removeControlListener, removeDragDetectListener, removeFocusListener, removeGestureListener, removeHelpListener, removeKeyListener, removeMenuDetectListener, removeMouseListener, removeMouseMoveListener, removeMouseTrackListener, removeMouseWheelListener, removePaintListener, removeTouchListener, removeTraverseListener, setBackground, setBackgroundImage, setBounds, setBounds, setCapture, setCursor, setDragDetect, setEnabled, setFocus, setFont, setForeground, setLayoutData, setLocation, setLocation, setMenu, setOrientation, setParent, setRedraw, setRegion, setSize, setSize, setToolTipText, setTouchEnabled, setVisible, toControl, toControl, toDisplay, toDisplay, traverse, traverse, traverse, 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, setData, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

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 Detail

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

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"

getEnabled

public boolean getEnabled()
Description copied from class: Control
Returns true if the receiver is enabled, and false otherwise. A disabled control is typically not selectable from the user interface and draws with an inactive or "grayed" look.

Overrides:
getEnabled in class Control
Returns:
the receiver's enabled state
See Also:
Control.isEnabled()

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 receiver's thumb value.

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

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)

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 thumb value. The thumb value should be used to represent the size of the visual portion of the current range. This value is usually the same as the page increment value.

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

Eclipse Platform
Release 4.2

Guidelines for using Eclipse APIs.

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