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Eclipse Rich Ajax Platform
Release 1.2

org.eclipse.swt.widgets
Class Button

java.lang.Object
  extended by

org.eclipse.swt.widgets.Widget
      extended by

org.eclipse.swt.widgets.Control
          extended by
org.eclipse.swt.widgets.Button
All Implemented Interfaces:
Adaptable

public class Button
extends Control

Instances of this class represent a selectable user interface object that issues notification when pressed and released.

Styles:
CHECK, PUSH, RADIO, TOGGLE, FLAT
LEFT, RIGHT, CENTER
Events:
Selection

Note: Only one of the styles CHECK, PUSH, RADIO, and TOGGLE may be specified.

Note: Only one of the styles LEFT, RIGHT, and CENTER may be specified.

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

Since:
1.0

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.
 boolean getGrayed ()
          Returns true if the receiver is grayed, and false otherwise.
  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.
 void setGrayed (boolean grayed)
          Sets the grayed state of the receiver.
 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 text)
          Sets the receiver's text.
 
Methods inherited from class org.eclipse.swt.widgets. Control
addControlListener, addFocusListener, addKeyListener, addMouseListener, addTraverseListener, computeSize, forceFocus, getAdapter, getBackground, getBackgroundImage, getBorderWidth, getBounds, getCursor, getEnabled, getFont, getForeground, getLayoutData, getLocation, getMenu, getMonitor, getParent, getShell, getSize, getToolTipText, getVisible, isEnabled, isFocusControl, isVisible, moveAbove, moveBelow, pack, pack, redraw, removeControlListener, removeFocusListener, removeKeyListener, removeMouseListener, removeTraverseListener, setBackground, setBackgroundImage, setBounds, setBounds, setCursor, setEnabled, setFocus, setFont, setForeground, setLayoutData, setLocation, setLocation, setMenu, setRedraw, setSize, setSize, setToolTipText, setVisible, toControl, toControl, toDisplay, toDisplay
 
Methods inherited from class org.eclipse.swt.widgets. Widget
addDisposeListener, addListener, checkSubclass, checkWidget, dispose, getData, getData, getDisplay, getStyle, isDisposed, notifyListeners, removeDisposeListener, removeListener, setData, setData, toString
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Button

public Button(
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.CHECK, SWT.PUSH, SWT.RADIO, SWT.TOGGLE, SWT.FLAT, SWT.LEFT, SWT.RIGHT, SWT.CENTER, Widget.checkSubclass(), Widget.getStyle()
Method Detail

setText

public void setText(
String text)
Sets the receiver's text.

This method sets the button label. The label may include the mnemonic character but must not contain line delimiters.

Caution: Mnemonics are not implemented yet. Mnemonics are indicated by an '&' that causes the next character to be the mnemonic. When the user presses a key sequence that matches the mnemonic, a selection event occurs. On most platforms, the mnemonic appears underlined but may be emphasised in a platform specific manner. The mnemonic indicator character '&' can be escaped by doubling it in the string, causing a single '&' to be displayed.

Parameters:
text - the new text
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the text 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

getText

public 
String getText()
Returns the receiver's text, which will be an empty string if it has never been set.

Returns:
the receiver's text
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 boolean getSelection()
Returns 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.

Returns:
the selection state
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(boolean selected)
Sets the selection state of the receiver, if it is of type 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.

Parameters:
selected - the new selection state
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

getGrayed

public boolean getGrayed()
Returns true if the receiver is grayed, and false otherwise. When the widget does not have the CHECK style, return false.

Returns:
the grayed state of the checkbox
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
Since:
1.2

setGrayed

public void setGrayed(boolean grayed)
Sets the grayed state of the receiver. This state change only applies if the control was created with the SWT.CHECK style.

Parameters:
grayed - the new grayed state
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
Since:
1.2

getImage

public 
Image getImage()
Returns the receiver's image if it has one, or null if it does not.

Returns:
the receiver's image
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

setImage

public void setImage(
Image image)
Sets the receiver's image to the argument, which may be null indicating that no image should be displayed.

Parameters:
image - the image to display on the receiver (may be null)
Throws:
IllegalArgumentException -
  • ERROR_INVALID_ARGUMENT - if the image has been disposed
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getAlignment

public int getAlignment()
Returns a value which describes the position of the text or image in the receiver. The value will be one of LEFT, RIGHT or CENTER .

Returns:
the alignment
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

setAlignment

public void setAlignment(int alignment)
Controls how text, images and arrows will be displayed in the receiver. The argument should be one of LEFT, RIGHT or CENTER .

Parameters:
alignment - the new alignment
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

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"

addSelectionListener

public 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.

widgetSelected is called when the control is selected. 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), SelectionEvent

removeSelectionListener

public void removeSelectionListener(
SelectionListener listener)
Removes the listener from the collection of listeners who will be notified when the control is selected.

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)

Eclipse Rich Ajax Platform
Release 1.2

Copyright (c) Innoopract Informationssysteme GmbH and others 2002, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire