Eclipse Plug-in Developer Guide (Galileo) - CLabel (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.swt.custom
Class CLabel


java.lang.Object
  

org.eclipse.swt.widgets.Widget
      

org.eclipse.swt.widgets.Control
          

org.eclipse.swt.widgets.Scrollable
              

org.eclipse.swt.widgets.Composite
                  

org.eclipse.swt.widgets.Canvas
                      
org.eclipse.swt.custom.CLabel

All Implemented Interfaces:: Drawable

public class CLabel
extends Canvas
extends Canvas

A Label which supports aligned text and/or an image and different border styles.

If there is not enough space a CLabel uses the following strategy to fit the information into the available space:

                ignores the indent in left align mode
                ignores the image and the gap
                shortens the text by replacing the center portion of the label with an ellipsis
                shortens the text by removing the center portion of the label

Styles:: LEFT, RIGHT, CENTER, SHADOW_IN, SHADOW_OUT, SHADOW_NONE
Events:

IMPORTANT: This class is not intended to be subclassed.

See Also:: SWT Example: CustomControlExample, 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

CLabel ( 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

Point computeSize (int wHint, int hHint, boolean changed)
          Returns the preferred size of the receiver.

int getAlignment ()
          Returns the alignment.

Image getImage ()
          Return the CLabel's image or null.

int getStyle ()
          Returns the receiver's style information.

String getText ()
          Return the Label's text.

String getToolTipText ()
          Returns the receiver's tool tip text, or null if it has not been set.

void setAlignment (int align)
          Set the alignment of the CLabel.

void setBackground ( Color color)
          Sets the receiver's background color to the color specified by the argument, or to the default system color for the control if the argument is null.

void setBackground ( Color[] colors, int[] percents)
          Specify a gradient of colours to be drawn in the background of the CLabel.

void setBackground ( Color[] colors, int[] percents, boolean vertical)
          Specify a gradient of colours to be drawn in the background of the CLabel.

void setBackground ( Image image)
          Set the image to be drawn in the background of the label.

void setFont ( Font font)
          Sets the font that the receiver will use to paint textual information to the font specified by the argument, or to the default font for that kind of control if the argument is null.

void setImage ( Image image)
          Set the label's Image.

void setText ( String text)
          Set the label's text.

void setToolTipText ( String string)
          Sets the receiver's tool tip text to the argument, which may be null indicating that the default tool tip for the control will be shown.

protected String shortenText ( GC gc, String t, int width)
          Shorten the given text t so that its length doesn't exceed the given width.

Methods inherited from class org.eclipse.swt.widgets. Canvas

drawBackground, getCaret, getIME, scroll, setCaret, setIME

Methods inherited from class org.eclipse.swt.widgets. Composite

changed, checkSubclass, getBackgroundMode, getChildren, getLayout, getLayoutDeferred, getTabList, isLayoutDeferred, layout, layout, layout, layout, setBackgroundMode, setFocus, setLayout, setLayoutDeferred, setTabList

Methods inherited from class org.eclipse.swt.widgets. Scrollable

computeTrim, getClientArea, getHorizontalBar, getVerticalBar

Methods inherited from class org.eclipse.swt.widgets. Control

addControlListener, addDragDetectListener, addFocusListener, addHelpListener, addKeyListener, addMenuDetectListener, addMouseListener, addMouseMoveListener, addMouseTrackListener, addMouseWheelListener, addPaintListener, addTraverseListener, computeSize, dragDetect, dragDetect, forceFocus, getAccessible, getBackground, getBackgroundImage, getBorderWidth, getBounds, getCursor, getDragDetect, getEnabled, getFont, getForeground, getLayoutData, getLocation, getMenu, getMonitor, getParent, getRegion, getShell, getSize, getVisible, internal_dispose_GC, internal_new_GC, isEnabled, isFocusControl, isReparentable, isVisible, moveAbove, moveBelow, pack, pack, print, redraw, redraw, removeControlListener, removeDragDetectListener, removeFocusListener, removeHelpListener, removeKeyListener, removeMenuDetectListener, removeMouseListener, removeMouseMoveListener, removeMouseTrackListener, removeMouseWheelListener, removePaintListener, removeTraverseListener, setBackgroundImage, setBounds, setBounds, setCapture, setCursor, setDragDetect, setEnabled, setForeground, setLayoutData, setLocation, setLocation, setMenu, setParent, setRedraw, setRegion, setSize, setSize, setVisible, toControl, toControl, toDisplay, toDisplay, traverse, update

Methods inherited from class org.eclipse.swt.widgets. Widget

addDisposeListener, addListener, checkWidget, dispose, getData, getData, getDisplay, getListeners, isDisposed, 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

CLabel

public CLabel(
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 widget which will be the parent of the new instance (cannot be null)

style - the style of widget 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

Method Detail

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 Composite

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"

getAlignment

public int getAlignment()

Returns the alignment. The alignment style (LEFT, CENTER or RIGHT) is returned.

Returns:: SWT.LEFT, SWT.RIGHT or SWT.CENTER

getImage

public 
Image getImage()

Return the CLabel's image or null.

Returns:: the image of the label or null

getStyle

public int getStyle()

Description copied from class: Widget

Returns the receiver's style information.

Note that the value which is returned by this method may not match the value which was provided to the constructor when the receiver was created. This can occur when the underlying operating system does not support a particular combination of requested styles. For example, if the platform widget used to implement a particular SWT widget always has scroll bars, the result of calling this method would always have the SWT.H_SCROLL and SWT.V_SCROLL bits set.

Overrides:: getStyle in class Widget

Returns:: the style bits

getText

public 
String getText()

Return the Label's text.

Returns:: the text of the label or null

getToolTipText

public 
String getToolTipText()

Description copied from class: Control

Returns the receiver's tool tip text, or null if it has not been set.

Overrides:: getToolTipText in class Control

Returns:: the receiver's tool tip text

setAlignment

public void setAlignment(int align)

Set the alignment of the CLabel. Use the values LEFT, CENTER and RIGHT to align image and text within the available space.

Parameters:

align - the alignment style of LEFT, RIGHT or CENTER

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
ERROR_INVALID_ARGUMENT - if the value of align is not one of SWT.LEFT, SWT.RIGHT or SWT.CENTER

setBackground

public void setBackground(
Color color)

Description copied from class: Control

Sets the receiver's background color to the color specified by the argument, or to the default system color for the control if the argument is null.

Note: This operation is a hint and may be overridden by the platform. For example, on Windows the background of a Button cannot be changed.

Overrides:: setBackground in class Control

Parameters:: color - the new color (or null)

setBackground

public void setBackground(
Color[] colors,
                          int[] percents)

Specify a gradient of colours to be drawn in the background of the CLabel.

For example, to draw a gradient that varies from dark blue to blue and then to white and stays white for the right half of the label, use the following call to setBackground:

        clabel.setBackground(new Color[]{display.getSystemColor(SWT.COLOR_DARK_BLUE), 
                                           display.getSystemColor(SWT.COLOR_BLUE),
                                           display.getSystemColor(SWT.COLOR_WHITE), 
                                           display.getSystemColor(SWT.COLOR_WHITE)},
                               new int[] {25, 50, 100});

Parameters:

colors - an array of Color that specifies the colors to appear in the gradient in order of appearance from left to right; The value null clears the background gradient; the value null can be used inside the array of Color to specify the background color.

percents - an array of integers between 0 and 100 specifying the percent of the width of the widget at which the color should change; the size of the percents array must be one less than the size of the colors array.

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
ERROR_INVALID_ARGUMENT - if the values of colors and percents are not consistent

setBackground

public void setBackground(
Color[] colors,
                          int[] percents,
                          boolean vertical)

Specify a gradient of colours to be drawn in the background of the CLabel.

For example, to draw a gradient that varies from dark blue to white in the vertical, direction use the following call to setBackground:

        clabel.setBackground(new Color[]{display.getSystemColor(SWT.COLOR_DARK_BLUE), 
                                           display.getSystemColor(SWT.COLOR_WHITE)},
                                 new int[] {100}, true);

Parameters:

colors - an array of Color that specifies the colors to appear in the gradient in order of appearance from left/top to right/bottom; The value null clears the background gradient; the value null can be used inside the array of Color to specify the background color.

percents - an array of integers between 0 and 100 specifying the percent of the width/height of the widget at which the color should change; the size of the percents array must be one less than the size of the colors array.

vertical - indicate the direction of the gradient. True is vertical and false is horizontal.

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
ERROR_INVALID_ARGUMENT - if the values of colors and percents are not consistent

Since:

3.0

setBackground

public void setBackground(
Image image)

Set the image to be drawn in the background of the label.

Parameters:

image - the image to be drawn in the background

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

setFont

public void setFont(
Font font)

Description copied from class: Control

Sets the font that the receiver will use to paint textual information to the font specified by the argument, or to the default font for that kind of control if the argument is null.

Overrides:: setFont in class Canvas

Parameters:: font - the new font (or null)

setImage

public void setImage(
Image image)

Set the label's Image. The value null clears it.

Parameters:

image - the image to be displayed in the label or null

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

setText

public void setText(
String text)

Set the label's text. The value null clears it.

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.

Parameters:

text - the text to be displayed in the label or null

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

setToolTipText

public void setToolTipText(
String string)

Description copied from class: Control

Sets the receiver's tool tip text to the argument, which may be null indicating that the default tool tip for the control will be shown. For a control that has a default tool tip, such as the Tree control on Windows, setting the tool tip text to an empty string replaces the default, causing no tool tip text to be shown.

The mnemonic indicator (character '&') is not displayed in a tool tip. To display a single '&' in the tool tip, the character '&' can be escaped by doubling it in the string.

Overrides:: setToolTipText in class Control

Parameters:: string - the new tool tip text (or null)

shortenText

protected 
String shortenText(
GC gc,
                             
String t,
                             int width)

Shorten the given text t so that its length doesn't exceed the given width. The default implementation replaces characters in the center of the original string with an ellipsis ("..."). Override if you need a different strategy.

Parameters:: gc - the gc to use for text measurement; t - the text to shorten; width - the width to shorten the text to, in pixels
Returns:: the shortened text

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Eclipse Platform
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Guidelines for using Eclipse APIs.

org.eclipse.swt.custom Class CLabel

CLabel

computeSize

getAlignment

getImage

getStyle

getText

getToolTipText

setAlignment

setBackground

setBackground

setBackground

setBackground

setFont

setImage

setText

setToolTipText

shortenText

org.eclipse.swt.custom
Class CLabel