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Eclipse Platform 2.0 |
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java.lang.Object | +--org.eclipse.swt.widgets.Widget | +--org.eclipse.swt.widgets.Control | +--org.eclipse.swt.widgets.Button
Instances of this class represent a selectable user interface object that issues notification when pressed and released.
Note: Only one of the styles ARROW, CHECK, PUSH, RADIO, and TOGGLE may be specified.
Note: Only one of the styles LEFT, RIGHT, and CENTER may be specified.
Note: Only one of the styles UP, DOWN, LEFT, and RIGHT may be specified when the ARROW style is specified.
IMPORTANT: This class is intended to be subclassed only within the SWT implementation.
Field Summary |
Fields inherited from class org.eclipse.swt.widgets.Control |
handle |
Constructor Summary | |
Button(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 control is selected, 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. |
int |
getAlignment()
Returns a value which describes the position of the text or image in the receiver. |
Image |
getImage()
Returns the receiver's image if it has one, or null if it does not. |
boolean |
getSelection()
Returns true if the receiver is selected,
and false otherwise. |
String |
getText()
Returns the receiver's text, which will be an empty string if it has never been set. |
void |
removeSelectionListener(SelectionListener listener)
Removes the listener from the collection of listeners who will be notified when the control is selected. |
void |
setAlignment(int alignment)
Controls how text, images and arrows will be displayed in the receiver. |
boolean |
setFocus()
Causes the receiver to have the keyboard focus, such that all keyboard events will be delivered to it. |
void |
setImage(Image image)
Sets the receiver's image to the argument, which may be null indicating that no image should be displayed. |
void |
setSelection(boolean selected)
Sets the selection state of the receiver, if it is of type CHECK ,
RADIO , or TOGGLE . |
void |
setText(String string)
Sets the receiver's text. |
Methods inherited from class org.eclipse.swt.widgets.Widget |
addDisposeListener, addListener, checkSubclass, checkWidget, dispose, getData, getData, getStyle, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, setData, setData, toString |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
public Button(Composite parent, int style)
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.
parent
- a composite control which will be the parent of the new instance (cannot be null)style
- the style of control to construct
IllegalArgumentException
- SWTException
- SWT.ARROW
,
SWT.CHECK
,
SWT.PUSH
,
SWT.RADIO
,
SWT.TOGGLE
,
SWT.FLAT
,
SWT.LEFT
,
SWT.RIGHT
,
SWT.CENTER
,
Widget.checkSubclass()
,
Widget.getStyle()
Method Detail |
public void addSelectionListener(SelectionListener listener)
SelectionListener
interface.
widgetSelected
is called when the control is selected.
widgetDefaultSelected
is not called.
listener
- the listener which should be notified
IllegalArgumentException
- SWTException
- SelectionListener
,
removeSelectionListener(org.eclipse.swt.events.SelectionListener)
,
SelectionEvent
public Point computeSize(int wHint, int hHint, boolean changed)
Control
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.
computeSize
in class Control
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
Layout
,
Control.getBorderWidth()
,
Control.getBounds()
,
Control.getSize()
,
Control.pack()
,
"computeTrim, getClientArea for controls that implement them"public int getAlignment()
LEFT
, RIGHT
or CENTER
unless the receiver is an ARROW
button, in
which case, the alignment will indicate the direction of
the arrow (one of LEFT
, RIGHT
,
UP
or DOWN
).
SWTException
- public Image getImage()
SWTException
- public boolean getSelection()
true
if the receiver is selected,
and false otherwise.
When the receiver is of type CHECK
or RADIO
,
it is selected when it is checked. When it is of type TOGGLE
,
it is selected when it is pushed in. If the receiver is of any other type,
this method returns false.
SWTException
- public String getText()
SWTException
- public void removeSelectionListener(SelectionListener listener)
listener
- the listener which should be notified
IllegalArgumentException
- SWTException
- SelectionListener
,
addSelectionListener(org.eclipse.swt.events.SelectionListener)
public void setAlignment(int alignment)
LEFT
, RIGHT
or CENTER
unless the receiver is an ARROW
button, in
which case, the argument indicates the direction of
the arrow (one of LEFT
, RIGHT
,
UP
or DOWN
).
alignment
- the new alignment
SWTException
- public boolean setFocus()
Control
setFocus
in class Control
true
if the control got focus, and false
if it was unable to.Control.forceFocus()
public void setImage(Image image)
image
- the image to display on the receiver (may be null)
IllegalArgumentException
- SWTException
- public void setSelection(boolean selected)
CHECK
,
RADIO
, or TOGGLE
.
When the receiver is of type CHECK
or RADIO
,
it is selected when it is checked. When it is of type TOGGLE
,
it is selected when it is pushed in.
selected
- the new selection state
SWTException
- public void setText(String string)
This method sets the button label. The label may include the mnemonic character but must not contain line delimiters.
string
- the new text
IllegalArgumentException
- SWTException
-
|
Eclipse Platform 2.0 |
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