Class 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:
    (NONE)

    This class may be subclassed for the purpose of overriding the default string shortening algorithm that is implemented in method shortenText().

    See Also:
    SWT Example: CustomControlExample, Sample code and further information, shortenText(GC, String, int)
    • 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
        See Also:
        SWT.LEFT, SWT.RIGHT, SWT.CENTER, SWT.SHADOW_IN, SWT.SHADOW_OUT, SWT.SHADOW_NONE, getStyle()
    • Method Detail

      • computeSize

        public Point computeSize​(int wHint,
                                 int hHint,
                                 boolean changed)
        Description copied from class: Control
        Returns the preferred size (in points) 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"
      • 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
      • 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
      • getTopMargin

        public int getTopMargin()
        Return the CLabel's top margin.
        Returns:
        the top margin of the label
        Since:
        3.6
      • 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.

        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 points.
        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 points.
        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 points.
        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 points.
        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​(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.

        Note: If control characters like '\n', '\t' etc. are used in the string, then the behavior is platform dependent.

        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.

        NOTE: This operation is a hint and behavior is platform specific, on Windows for CJK-style mnemonics of the form " (&C)" at the end of the tooltip text are not shown in tooltip.

        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 points.
        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 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 points
        Returns:
        the shortened text