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org.eclipse.swt.widgets
Class Label
java.lang.Object
org.eclipse.swt.widgets.Widget
org.eclipse.swt.widgets.Control
org.eclipse.swt.widgets.Label
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All Implemented Interfaces:
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Adaptable
- public class Label
- extends
Control
Instances of this class represent a non-selectable
user interface object that displays a string or image.
When SEPARATOR is specified, displays a single
vertical or horizontal line.
Shadow styles are hints and may not be honoured
by the platform. To create a separator label
with the default shadow style for the platform,
do not specify a shadow style.
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Styles:
- SEPARATOR, HORIZONTAL, VERTICAL
- SHADOW_IN, SHADOW_OUT, SHADOW_NONE
- CENTER, LEFT, RIGHT, WRAP
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Events:
- (none)
Note: Only one of SHADOW_IN, SHADOW_OUT and SHADOW_NONE may be specified.
SHADOW_NONE is a HINT. Only one of HORIZONTAL and VERTICAL may be specified.
Only one of CENTER, LEFT and RIGHT may be specified.
IMPORTANT: This class is intended to be subclassed only
within the SWT implementation.
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Since:
- 1.0
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See Also:
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Label snippets,
SWT Example: ControlExample,
Sample code and further information
Note: Unlike in SWT, setting an image clears the text of the
label and vice versa. Thus, after calling setText(), the method
getImage() will return null, and after calling
setImage(), getText will return the empty string.
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Constructor Summary
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Label
(
Composite parent,
int style)
Constructs a new instance of this class given its parent
and a style value describing its behavior and appearance. |
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Method Summary
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Point
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computeSize
(int wHint,
int hHint,
boolean changed)
Returns the preferred size of the receiver. |
int
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getAlignment
()
Returns a value which describes the position of the
text or image in the receiver. |
Image
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getImage
()
Returns the receiver's image if it has one, or null
if it does not. |
String
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getText
()
Returns the receiver's text, which will be an empty
string if it has never been set or if the receiver is
a SEPARATOR label. |
void
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setAlignment
(int alignment)
Controls how text and images will be displayed in the receiver. |
void
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setImage
(
Image image)
Sets the receiver's image to the argument, which may be
null indicating that no image should be displayed. |
void
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setText
(
String text)
Sets the receiver's text. |
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Methods inherited from class org.eclipse.swt.widgets.
Control
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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
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Methods inherited from class org.eclipse.swt.widgets.
Widget
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addDisposeListener,
addListener,
checkSubclass,
checkWidget,
dispose,
getData,
getData,
getDisplay,
getStyle,
isDisposed,
notifyListeners,
removeDisposeListener,
removeListener,
setData,
setData,
toString
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Label
public Label(
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.
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Parameters:
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parent - a composite control which will be the parent of the new instance (cannot be null) -
style - the style of control to construct
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Throws:
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IllegalArgumentException
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- ERROR_NULL_ARGUMENT - if the parent is null
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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
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See Also:
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SWT.SEPARATOR,
SWT.HORIZONTAL,
SWT.VERTICAL,
SWT.SHADOW_IN,
SWT.SHADOW_OUT,
SWT.SHADOW_NONE,
SWT.CENTER,
SWT.LEFT,
SWT.RIGHT,
SWT.WRAP,
Widget.checkSubclass(),
Widget.getStyle()
setText
public void setText(
String text)
- Sets the receiver's text.
This method sets the widget label. The label may include
the mnemonic character and line delimiters.
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, focus is assigned
to the control that follows the label. 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.
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Parameters:
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text - the new text
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Throws:
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IllegalArgumentException
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- ERROR_NULL_ARGUMENT - if the text is null
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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 or if the receiver is
a
SEPARATOR label.
-
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Returns:
- the receiver's text
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Throws:
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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.
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Parameters:
-
image - the image to display on the receiver (may be null)
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Throws:
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IllegalArgumentException
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- ERROR_INVALID_ARGUMENT - if the image has been disposed
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SWTException -
- ERROR_WIDGET_DISPOSED - if the receiver has been disposed
- ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
getImage
public
Image getImage()
- Returns the receiver's image if it has one, or null
if it does not.
-
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Returns:
- the receiver's image
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Throws:
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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 and images will be displayed in the receiver.
The argument should be one of
LEFT, RIGHT
or CENTER. If the receiver is a SEPARATOR
label, the argument is ignored and the alignment is not changed.
-
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Parameters:
-
alignment - the new alignment
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Throws:
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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
unless the receiver is a SEPARATOR label, in
which case, NONE is returned.
-
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Returns:
- the alignment
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Throws:
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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)
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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.
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Overrides:
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computeSize
in class
Control
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Parameters:
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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
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Returns:
- the preferred size of the control.
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See Also:
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Layout,
Control.getBorderWidth(),
Control.getBounds(),
Control.getSize(),
Control.pack(boolean),
"computeTrim, getClientArea for controls that implement them"
Copyright (c) Innoopract Informationssysteme GmbH and others 2002, 2008. All rights reserved.
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