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package javax.swing.text;

import java.awt.*;
import javax.swing.event.*;


A LabelView is a styled chunk of text
that represents a view mapped over an element in the
text model.  It caches the character level attributes
used for rendering.

Author:Timothy Prinzing
/**
 * A <code>LabelView</code> is a styled chunk of text
 * that represents a view mapped over an element in the
 * text model.  It caches the character level attributes
 * used for rendering.
 *
 * @author Timothy Prinzing
 */
public class LabelView extends GlyphView implements TabableView {

    
Constructs a new view wrapped on an element.

Params:
  • elem – the element
/**
     * Constructs a new view wrapped on an element.
     *
     * @param elem the element
     */
    public LabelView(Element elem) {
        super(elem);
    }

    
Synchronize the view's cached values with the model.
This causes the font, metrics, color, etc to be
re-cached if the cache has been invalidated.

/**
     * Synchronize the view's cached values with the model.
     * This causes the font, metrics, color, etc to be
     * re-cached if the cache has been invalidated.
     */
    final void sync() {
        if (font == null) {
            setPropertiesFromAttributes();
        }
    }

    
Sets whether or not the view is underlined.
Note that this setter is protected and is really
only meant if you need to update some additional
state when set.

Params:
  • u – true if the view is underlined, otherwise
         false
See Also:
/**
     * Sets whether or not the view is underlined.
     * Note that this setter is protected and is really
     * only meant if you need to update some additional
     * state when set.
     *
     * @param u true if the view is underlined, otherwise
     *          false
     * @see #isUnderline
     */
    protected void setUnderline(boolean u) {
        underline = u;
    }

    
Sets whether or not the view has a strike/line
through it.
Note that this setter is protected and is really
only meant if you need to update some additional
state when set.

Params:
  • s – true if the view has a strike/line
         through it, otherwise false
See Also:
/**
     * Sets whether or not the view has a strike/line
     * through it.
     * Note that this setter is protected and is really
     * only meant if you need to update some additional
     * state when set.
     *
     * @param s true if the view has a strike/line
     *          through it, otherwise false
     * @see #isStrikeThrough
     */
    protected void setStrikeThrough(boolean s) {
        strike = s;
    }


    
Sets whether or not the view represents a
superscript.
Note that this setter is protected and is really
only meant if you need to update some additional
state when set.

Params:
  • s – true if the view represents a
         superscript, otherwise false
See Also:
/**
     * Sets whether or not the view represents a
     * superscript.
     * Note that this setter is protected and is really
     * only meant if you need to update some additional
     * state when set.
     *
     * @param s true if the view represents a
     *          superscript, otherwise false
     * @see #isSuperscript
     */
    protected void setSuperscript(boolean s) {
        superscript = s;
    }

    
Sets whether or not the view represents a
subscript.
Note that this setter is protected and is really
only meant if you need to update some additional
state when set.

Params:
  • s – true if the view represents a
         subscript, otherwise false
See Also:
/**
     * Sets whether or not the view represents a
     * subscript.
     * Note that this setter is protected and is really
     * only meant if you need to update some additional
     * state when set.
     *
     * @param s true if the view represents a
     *          subscript, otherwise false
     * @see #isSubscript
     */
    protected void setSubscript(boolean s) {
        subscript = s;
    }

    
Sets the background color for the view. This method is typically
invoked as part of configuring this View. If you need
to customize the background color you should override
setPropertiesFromAttributes and invoke this method. A
value of null indicates no background should be rendered, so that the
background of the parent View will show through.

Params:
  • bg – background color, or null
See Also:
Since:1.5
/**
     * Sets the background color for the view. This method is typically
     * invoked as part of configuring this <code>View</code>. If you need
     * to customize the background color you should override
     * <code>setPropertiesFromAttributes</code> and invoke this method. A
     * value of null indicates no background should be rendered, so that the
     * background of the parent <code>View</code> will show through.
     *
     * @param bg background color, or null
     * @see #setPropertiesFromAttributes
     * @since 1.5
     */
    protected void setBackground(Color bg) {
        this.bg = bg;
    }

    
Sets the cached properties from the attributes.

/**
     * Sets the cached properties from the attributes.
     */
    protected void setPropertiesFromAttributes() {
        AttributeSet attr = getAttributes();
        if (attr != null) {
            Document d = getDocument();
            if (d instanceof StyledDocument) {
                StyledDocument doc = (StyledDocument) d;
                font = doc.getFont(attr);
                fg = doc.getForeground(attr);
                if (attr.isDefined(StyleConstants.Background)) {
                    bg = doc.getBackground(attr);
                } else {
                    bg = null;
                }
                setUnderline(StyleConstants.isUnderline(attr));
                setStrikeThrough(StyleConstants.isStrikeThrough(attr));
                setSuperscript(StyleConstants.isSuperscript(attr));
                setSubscript(StyleConstants.isSubscript(attr));
            } else {
                throw new StateInvariantError("LabelView needs StyledDocument");
            }
        }
     }

    
Fetches the FontMetrics used for this view.

Deprecated:FontMetrics are not used for glyph rendering
 when running in the JDK.
/**
     * Fetches the <code>FontMetrics</code> used for this view.
     * @deprecated FontMetrics are not used for glyph rendering
     *  when running in the JDK.
     */
    @Deprecated
    protected FontMetrics getFontMetrics() {
        sync();
        Container c = getContainer();
        return (c != null) ? c.getFontMetrics(font) :
            Toolkit.getDefaultToolkit().getFontMetrics(font);
    }

    
Fetches the background color to use to render the glyphs.
This is implemented to return a cached background color,
which defaults to null.

Returns:the cached background color
Since:1.3
/**
     * Fetches the background color to use to render the glyphs.
     * This is implemented to return a cached background color,
     * which defaults to <code>null</code>.
     *
     * @return the cached background color
     * @since 1.3
     */
    public Color getBackground() {
        sync();
        return bg;
    }

    
Fetches the foreground color to use to render the glyphs.
This is implemented to return a cached foreground color,
which defaults to null.

Returns:the cached foreground color
Since:1.3
/**
     * Fetches the foreground color to use to render the glyphs.
     * This is implemented to return a cached foreground color,
     * which defaults to <code>null</code>.
     *
     * @return the cached foreground color
     * @since 1.3
     */
    public Color getForeground() {
        sync();
        return fg;
    }

    
Fetches the font that the glyphs should be based upon.
This is implemented to return a cached font.

Returns:the cached font
/**
     * Fetches the font that the glyphs should be based upon.
     * This is implemented to return a cached font.
     *
     * @return the cached font
     */
     public Font getFont() {
        sync();
        return font;
    }

    
Determines if the glyphs should be underlined.  If true,
an underline should be drawn through the baseline.  This
is implemented to return the cached underline property.

When you request this property, LabelView
re-syncs its state with the properties of the
Element's AttributeSet.
If Element's AttributeSet
does not have this property set, it will revert to false.

Returns:the value of the cached
    underline property
Since:1.3
/**
     * Determines if the glyphs should be underlined.  If true,
     * an underline should be drawn through the baseline.  This
     * is implemented to return the cached underline property.
     *
     * <p>When you request this property, <code>LabelView</code>
     * re-syncs its state with the properties of the
     * <code>Element</code>'s <code>AttributeSet</code>.
     * If <code>Element</code>'s <code>AttributeSet</code>
     * does not have this property set, it will revert to false.
     *
     * @return the value of the cached
     *     <code>underline</code> property
     * @since 1.3
     */
    public boolean isUnderline() {
        sync();
        return underline;
    }

    
Determines if the glyphs should have a strikethrough
line.  If true, a line should be drawn through the center
of the glyphs.  This is implemented to return the
cached strikeThrough property.

When you request this property, LabelView
re-syncs its state with the properties of the
Element's AttributeSet.
If Element's AttributeSet
does not have this property set, it will revert to false.

Returns:the value of the cached
    strikeThrough property
Since:1.3
/**
     * Determines if the glyphs should have a strikethrough
     * line.  If true, a line should be drawn through the center
     * of the glyphs.  This is implemented to return the
     * cached <code>strikeThrough</code> property.
     *
     * <p>When you request this property, <code>LabelView</code>
     * re-syncs its state with the properties of the
     * <code>Element</code>'s <code>AttributeSet</code>.
     * If <code>Element</code>'s <code>AttributeSet</code>
     * does not have this property set, it will revert to false.
     *
     * @return the value of the cached
     *     <code>strikeThrough</code> property
     * @since 1.3
     */
    public boolean isStrikeThrough() {
        sync();
        return strike;
    }

    
Determines if the glyphs should be rendered as superscript.

Returns:the value of the cached subscript property

When you request this property, LabelView
re-syncs its state with the properties of the
Element's AttributeSet.
If Element's AttributeSet
does not have this property set, it will revert to false.
Returns:the value of the cached
    subscript property
Since:1.3
/**
     * Determines if the glyphs should be rendered as superscript.
     * @return the value of the cached subscript property
     *
     * <p>When you request this property, <code>LabelView</code>
     * re-syncs its state with the properties of the
     * <code>Element</code>'s <code>AttributeSet</code>.
     * If <code>Element</code>'s <code>AttributeSet</code>
     * does not have this property set, it will revert to false.
     *
     * @return the value of the cached
     *     <code>subscript</code> property
     * @since 1.3
     */
    public boolean isSubscript() {
        sync();
        return subscript;
    }

    
Determines if the glyphs should be rendered as subscript.

When you request this property, LabelView
re-syncs its state with the properties of the
Element's AttributeSet.
If Element's AttributeSet
does not have this property set, it will revert to false.

Returns:the value of the cached
    superscript property
Since:1.3
/**
     * Determines if the glyphs should be rendered as subscript.
     *
     * <p>When you request this property, <code>LabelView</code>
     * re-syncs its state with the properties of the
     * <code>Element</code>'s <code>AttributeSet</code>.
     * If <code>Element</code>'s <code>AttributeSet</code>
     * does not have this property set, it will revert to false.
     *
     * @return the value of the cached
     *     <code>superscript</code> property
     * @since 1.3
     */
    public boolean isSuperscript() {
        sync();
        return superscript;
    }

    // --- View methods ---------------------------------------------

    
Gives notification from the document that attributes were changed
in a location that this view is responsible for.

Params:
  • e – the change information from the associated document
  • a – the current allocation of the view
  • f – the factory to use to rebuild if the view has children
See Also:
/**
     * Gives notification from the document that attributes were changed
     * in a location that this view is responsible for.
     *
     * @param e the change information from the associated document
     * @param a the current allocation of the view
     * @param f the factory to use to rebuild if the view has children
     * @see View#changedUpdate
     */
    public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
        font = null;
        super.changedUpdate(e, a, f);
    }

    // --- variables ------------------------------------------------

    private Font font;
    private Color fg;
    private Color bg;
    private boolean underline;
    private boolean strike;
    private boolean superscript;
    private boolean subscript;

}