public class ScrollBar extends Widget
At any given moment, a given scroll bar will have a single 'selection' that is considered to be its value, which is constrained to be within the range of values the scroll bar represents (that is, between its minimum and maximum values).
Typically, scroll bars will be made up of five areas:
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 scroll bar'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 scroll bar will not change.
Scroll bars are created by specifying either H_SCROLL
,
V_SCROLL
or both when creating a Scrollable
.
They are accessed from the Scrollable
using
getHorizontalBar
and getVerticalBar
.
Note: Scroll bars are not Controls. On some platforms, scroll bars
that appear as part of some standard controls such as a text or list
have no operating system resources and are not children of the control.
For this reason, scroll bars are treated specially. To create a control
that looks like a scroll bar but has operating system resources, use
Slider
.
Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
IMPORTANT: This class is not intended to be subclassed.
Modifier and Type | Method and Description |
---|---|
void |
addSelectionListener(SelectionListener listener)
Adds the listener to the collection of listeners who will
be notified when the receiver's value changes, by sending
it one of the messages defined in the
SelectionListener
interface. |
<T> T |
getAdapter(java.lang.Class<T> adapter)
Implementation of the
Adaptable interface. |
boolean |
getEnabled()
Returns
true if the receiver is enabled, and
false otherwise. |
int |
getMaximum()
Returns the maximum value which the receiver will allow.
|
int |
getMinimum()
Returns the minimum value which the receiver will allow.
|
Scrollable |
getParent()
Returns the receiver's parent, which must be a Scrollable.
|
int |
getSelection()
Returns the single 'selection' that is the receiver's value.
|
Point |
getSize()
Returns a point describing the receiver's size.
|
int |
getThumb()
Returns the size of the receiver's thumb relative to the
difference between its maximum and minimum values.
|
boolean |
getVisible()
Returns
true if the receiver is visible, and
false otherwise. |
boolean |
isEnabled()
Returns
true if the receiver is enabled and all
of the receiver's ancestors are enabled, and false
otherwise. |
boolean |
isVisible()
Returns
true if the receiver is visible and all
of the receiver's ancestors are visible and false
otherwise. |
void |
removeSelectionListener(SelectionListener listener)
Removes the listener from the collection of listeners who will
be notified when the receiver's value changes.
|
void |
setEnabled(boolean enabled)
Enables the receiver if the argument is
true ,
and disables it otherwise. |
void |
setMaximum(int maximum)
Sets the maximum.
|
void |
setMinimum(int minimum)
Sets the minimum value.
|
void |
setSelection(int selection)
Sets the single selection that is the receiver's
value to the argument which must be greater than or equal
to zero.
|
void |
setThumb(int thumb)
Sets the size of the receiver's thumb relative to the
difference between its maximum and minimum values.
|
void |
setVisible(boolean visible)
Marks the receiver as visible if the argument is
true ,
and marks it invisible otherwise. |
addDisposeListener, addListener, checkSubclass, checkWidget, dispose, getData, getData, getDisplay, getListeners, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, reskin, setData, setData, toString
public Scrollable getParent()
SWTException
- public void setVisible(boolean visible)
true
,
and marks it invisible otherwise.
If one of the receiver's ancestors is not visible or some other condition makes the receiver not visible, marking it visible may not actually cause it to be displayed.
visible
- the new visibility stateSWTException
- public boolean getVisible()
true
if the receiver is visible, and
false
otherwise.
If one of the receiver's ancestors is not visible or some other condition makes the receiver not visible, this method may still indicate that it is considered visible even though it may not actually be showing.
SWTException
- public boolean isVisible()
true
if the receiver is visible and all
of the receiver's ancestors are visible and false
otherwise.SWTException
- getVisible()
public void setEnabled(boolean enabled)
true
,
and disables it otherwise. A disabled control is typically
not selectable from the user interface and draws with an
inactive or "grayed" look.enabled
- the new enabled stateSWTException
- public boolean getEnabled()
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.SWTException
- isEnabled()
public boolean isEnabled()
true
if the receiver is enabled and all
of the receiver's ancestors are enabled, and false
otherwise. A disabled control is typically not selectable from the
user interface and draws with an inactive or "grayed" look.SWTException
- getEnabled()
public Point getSize()
SWTException
- public int getThumb()
SWTException
- ScrollBar
public void setThumb(int thumb)
thumb
- the new thumb value, which must be at least one and not
larger than the size of the current rangeSWTException
- public int getMaximum()
SWTException
- public void setMaximum(int maximum)
maximum
- the new maximumSWTException
- public int getMinimum()
SWTException
- public void setMinimum(int minimum)
minimum
- the new minimumSWTException
- public void setSelection(int selection)
selection
- the new selection (must be zero or greater)SWTException
- public int getSelection()
SWTException
- public void addSelectionListener(SelectionListener listener)
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.
listener
- the listener which should be notifiedjava.lang.IllegalArgumentException
- SWTException
- SelectionListener
,
removeSelectionListener(org.eclipse.swt.events.SelectionListener)
,
SelectionEvent
public void removeSelectionListener(SelectionListener listener)
listener
- the listener which should no longer be notifiedjava.lang.IllegalArgumentException
- SWTException
- SelectionListener
,
addSelectionListener(org.eclipse.swt.events.SelectionListener)
public <T> T getAdapter(java.lang.Class<T> adapter)
Widget
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.
getAdapter
in interface Adaptable
getAdapter
in class Widget
adapter
- the lookup classnull
if
there is no adapter associated with the given class.
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All rights reserved. This program and the accompanying materials
are made available under the terms of the
Eclipse Public License v1.0