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

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

Structure Diagram

Field Summary

Fields

Modifier and Type	Field and Description
private int	align the alignment.
private java.lang.String	appToolTipText
private Color	background
private Image	backgroundImage
private int	bottomMargin
private static int	DEFAULT_MARGIN Left and right margins
private static int	DRAW_FLAGS
private static java.lang.String	ELLIPSIS a string inserted in the middle of text that has been shortened
private static int	GAP Gap between icon and text
private Color[]	gradientColors
private int[]	gradientPercents
private boolean	gradientVertical
private boolean	ignoreDispose
private Image	image the current icon
private int	leftMargin
private int	rightMargin
private java.lang.String	text the current text
private int	topMargin

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

handle

Constructor Summary

Constructors

Constructor and Description
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

Methods

Modifier and Type	Method and Description
(package private) char	_findMnemonic(java.lang.String string)
private static int	checkStyle(int style) Check the style bits to ensure that no invalid styles are applied.
Point	computeSize(int wHint, int hHint, boolean changed) Returns the preferred size of the receiver.
private void	drawBevelRect(GC gc, int x, int y, int w, int h, Color topleft, Color bottomright) Draw a rectangle in the given colors.
int	getAlignment() Returns the horizontal alignment.
int	getBottomMargin() Return the CLabel's bottom margin.
Image	getImage() Return the CLabel's image or null.
int	getLeftMargin() Return the CLabel's left margin.
int	getRightMargin() Return the CLabel's right margin.
int	getStyle() Returns the receiver's style information.
java.lang.String	getText() Return the Label's text.
java.lang.String	getToolTipText() Returns the receiver's tool tip text, or null if it has not been set.
int	getTopMargin() Return the CLabel's top margin.
private Point	getTotalSize(Image image, java.lang.String text) Compute the minimum size.
private void	initAccessible()
(package private) void	onDispose(Event event)
(package private) void	onMnemonic(TraverseEvent event)
(package private) void	onPaint(PaintEvent event)
private void	paintBorder(GC gc, Rectangle r) Paint the Label's border.
void	setAlignment(int align) Set the horizontal 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	setBottomMargin(int bottomMargin) Set the label's bottom margin, in pixels.
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	setLeftMargin(int leftMargin) Set the label's horizontal left margin, in pixels.
void	setMargins(int leftMargin, int topMargin, int rightMargin, int bottomMargin) Set the label's margins, in pixels.
void	setRightMargin(int rightMargin) Set the label's right margin, in pixels.
void	setText(java.lang.String text) Set the label's text.
void	setToolTipText(java.lang.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.
void	setTopMargin(int topMargin) Set the label's top margin, in pixels.
protected java.lang.String	shortenText(GC gc, java.lang.String t, int width) Shorten the given text t so that its length doesn't exceed the given width.
private java.lang.String[]	splitString(java.lang.String text)
(package private) int	validateOffset(TextLayout layout, int offset)

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

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

computeTrim, getClientArea, getHorizontalBar, getScrollbarsMode, getVerticalBar

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

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

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

GAP

private static final int GAP

Gap between icon and text

See Also:

Constant Field Values

DEFAULT_MARGIN

private static final int DEFAULT_MARGIN

Left and right margins

See Also:

Constant Field Values

ELLIPSIS

private static final java.lang.String ELLIPSIS

a string inserted in the middle of text that has been shortened

See Also:

Constant Field Values

align

private int align

the alignment. Either CENTER, RIGHT, LEFT. Default is LEFT

leftMargin

private int leftMargin

topMargin

private int topMargin

rightMargin

private int rightMargin

bottomMargin

private int bottomMargin

text

private java.lang.String text

the current text

image

private Image image

the current icon

appToolTipText

private java.lang.String appToolTipText

ignoreDispose

private boolean ignoreDispose

backgroundImage

private Image backgroundImage

gradientColors

private Color[] gradientColors

gradientPercents

private int[] gradientPercents

gradientVertical

private boolean gradientVertical

background

private Color background

DRAW_FLAGS

private static int DRAW_FLAGS

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:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent

See Also:

SWT.LEFT, SWT.RIGHT, SWT.CENTER, SWT.SHADOW_IN, SWT.SHADOW_OUT, SWT.SHADOW_NONE, getStyle()

Method Detail

checkStyle

private static int checkStyle(int style)

Check the style bits to ensure that no invalid styles are applied.

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"

drawBevelRect

private void drawBevelRect(GC gc,
                 int x,
                 int y,
                 int w,
                 int h,
                 Color topleft,
                 Color bottomright)

Draw a rectangle in the given colors.

_findMnemonic

char _findMnemonic(java.lang.String string)

getAlignment

public int getAlignment()

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

Returns:

SWT.LEFT, SWT.RIGHT or SWT.CENTER

getBottomMargin

public int getBottomMargin()

Return the CLabel's bottom margin.

Returns:

the bottom margin of the label

Since:

3.6

getImage

public Image getImage()

Return the CLabel's image or null.

Returns:

the image of the label or null

getLeftMargin

public int getLeftMargin()

Return the CLabel's left margin.

Returns:

the left margin of the label

Since:

3.6

getRightMargin

public int getRightMargin()

Return the CLabel's right margin.

Returns:

the right margin of the label

Since:

3.6

getTotalSize

private Point getTotalSize(Image image,
                 java.lang.String text)

Compute the minimum size.

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 java.lang.String getText()

Return the Label's text.

Returns:

the text of the label or null

getToolTipText

public java.lang.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

getTopMargin

public int getTopMargin()

Return the CLabel's top margin.

Returns:

the top margin of the label

Since:

3.6

initAccessible

private void initAccessible()

onDispose

void onDispose(Event event)

onMnemonic

void onMnemonic(TraverseEvent event)

onPaint

void onPaint(PaintEvent event)

paintBorder

private void paintBorder(GC gc,
               Rectangle r)

Paint the Label's border.

setAlignment

public void setAlignment(int align)

Set the horizontal 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

setBottomMargin

public void setBottomMargin(int bottomMargin)

Set the label's bottom margin, in pixels.

Parameters:

bottomMargin - the bottom margin of the label, which must be equal to or greater than zero

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:

3.6

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

setLeftMargin

public void setLeftMargin(int leftMargin)

Set the label's horizontal left margin, in pixels.

Parameters:

leftMargin - the left margin of the label, which must be equal to or greater than zero

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:

3.6

setMargins

public void setMargins(int leftMargin,
              int topMargin,
              int rightMargin,
              int bottomMargin)

Set the label's margins, in pixels.

Parameters:

leftMargin - the left margin.

topMargin - the top margin.

rightMargin - the right margin.

bottomMargin - the bottom margin.

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:

3.6

setRightMargin

public void setRightMargin(int rightMargin)

Set the label's right margin, in pixels.

Parameters:

rightMargin - the right margin of the label, which must be equal to or greater than zero

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:

3.6

setText

public void setText(java.lang.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(java.lang.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)

setTopMargin

public void setTopMargin(int topMargin)

Set the label's top margin, in pixels.

Parameters:

topMargin - the top margin of the label, which must be equal to or greater than zero

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:

3.6

shortenText

protected java.lang.String shortenText(GC gc,
                           java.lang.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

validateOffset

int validateOffset(TextLayout layout,
                 int offset)

splitString

private java.lang.String[] splitString(java.lang.String text)