漫谈可视化Prefuse（五）---一款属于我自己的可视化工具

package prefuse.render;

import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Arc2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RectangularShape;
import java.awt.geom.RoundRectangle2D;

import prefuse.Constants;
import prefuse.util.ColorLib;
import prefuse.util.FontLib;
import prefuse.util.GraphicsLib;
import prefuse.util.StringLib;
import prefuse.visual.VisualItem;


/**渲染一个包含或文本或图片或兼有之的label标签
 * Renderer that draws a label, which consists of a text string,
 * an image, or both.
 * 
 * <p>When created using the default constructor, the renderer attempts
 * to use text from the "label" field. To use a different field, use the
 * appropriate constructor or use the {@link #setTextField(String)} method.
 * To perform custom String selection, subclass this Renderer and override the 
 * {@link #getText(VisualItem)} method. When the text field is
 * <code>null</code>, no text label will be shown. Labels can span multiple
 * lines of text, determined by the presence of newline characters ('\n')
 * within the text string.</p>
 * 
 * <p>By default, no image is shown. To show an image, the image field needs
 * to be set, either using the appropriate constructor or the
 * {@link #setImageField(String)} method. The value of the image field should
 * be a text string indicating the location of the image file to use. The
 * string should be either a URL, a file located on the current classpath,
 * or a file on the local filesystem. If found, the image will be managed
 * internally by an {@link ImageFactory} instance, which maintains a
 * cache of loaded images.</p>
 * 
 * <p>The position of the image relative to text can be set using the
 * {@link #setImagePosition(int)} method. Images can be placed to the
 * left, right, above, or below the text. The horizontal and vertical
 * alignments of either the text or the image can be set explicitly
 * using the appropriate methods of this class (e.g.,
 * {@link #setHorizontalTextAlignment(int)}). By default, both the
 * text and images are centered along both the horizontal and
 * vertical directions.</p>
 * 
 * @author <a href="http://jheer.org">jeffrey heer</a>
 */
public class LabelRenderer extends AbstractShapeRenderer {

    protected ImageFactory m_images = null;
    protected String m_delim = "\n";
    
    protected String m_labelName = "label";
    protected String m_imageName = null;
    
    protected int m_xAlign = Constants.CENTER;
    protected int m_yAlign = Constants.CENTER;
    protected int m_hTextAlign = Constants.CENTER;
    protected int m_vTextAlign = Constants.CENTER;
    protected int m_hImageAlign = Constants.CENTER;
    protected int m_vImageAlign = Constants.CENTER;
    protected int m_imagePos = Constants.LEFT;
    
    protected int m_horizBorder = 2;
    protected int m_vertBorder  = 0;
    protected int m_imageMargin = 2;
    protected int m_arcWidth    = 0;
    protected int m_arcHeight   = 0;

    protected int m_maxTextWidth = -1;
    
    /** Transform used to scale and position images */
    AffineTransform m_transform = new AffineTransform();
    
    /** The holder for the currently computed bounding box */
    protected RectangularShape m_bbox  = new Rectangle2D.Double();    // Prefuse框架自带的，即默认使用矩形
    protected Point2D m_pt = new Point2D.Double(); // temp point
    protected Font    m_font; // temp font holder
    protected String    m_text; // label text
    protected Dimension m_textDim = new Dimension(); // text width / height

    /**
     * Create a new LabelRenderer. By default the field "label" is used
     * as the field name for looking up text, and no image is used.
     */
    public LabelRenderer() {
    }
    
    /**
     * Create a new LabelRenderer. Draws a text label using the given
     * text data field and does not draw an image.
     * @param textField the data field for the text label.
     */
    public LabelRenderer(String textField) {
        this.setTextField(textField);
    }
    
    /**
     * Create a new LabelRenderer. Draws a text label using the given text
     * data field, and draws the image at the location reported by the
     * given image data field.
     * @param textField the data field for the text label
     * @param imageField the data field for the image location. This value
     * in the data field should be a URL, a file within the current classpath,
     * a file on the filesystem, or null for no image. If the
     * <code>imageField</code> parameter is null, no images at all will be
     * drawn.
     */
    public LabelRenderer(String textField, String imageField) {
        setTextField(textField);
        setImageField(imageField);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Rounds the corners of the bounding rectangle in which the text
     * string is rendered. This will only be seen if either the stroke
     * or fill color is non-transparent.
     * @param arcWidth the width of the curved corner
     * @param arcHeight the height of the curved corner
     */
    public void setRoundedCorner(int arcWidth, int arcHeight) {
        if ( (arcWidth == 0 || arcHeight == 0) && 
            !(m_bbox instanceof Rectangle2D) ) {
            m_bbox = new Rectangle2D.Double();
        } else {
            if ( !(m_bbox instanceof RoundRectangle2D) )
                m_bbox = new RoundRectangle2D.Double();
            ((RoundRectangle2D)m_bbox)
                .setRoundRect(0,0,10,10,arcWidth,arcHeight);
            m_arcWidth = arcWidth;
            m_arcHeight = arcHeight;
        }
    }

    /**
     * Get the field name to use for text labels.
     * @return the data field for text labels, or null for no text
     */
    public String getTextField() {
        return m_labelName;
    }
    
    /**
     * Set the field name to use for text labels.
     * @param textField the data field for text labels, or null for no text
     */
    public void setTextField(String textField) {
        m_labelName = textField;
    }
    
    /**
     * Sets the maximum width that should be allowed of the text label.
     * A value of -1 specifies no limit (this is the default).
     * @param maxWidth the maximum width of the text or -1 for no limit
     */
    public void setMaxTextWidth(int maxWidth) {
        m_maxTextWidth = maxWidth;
    }
    
    /**
     * Returns the text to draw. Subclasses can override this class to
     * perform custom text selection.
     * @param item the item to represent as a <code>String</code>
     * @return a <code>String</code> to draw
     */
    protected String getText(VisualItem item) {
        String s = null;
        if ( item.canGetString(m_labelName) ) {
            return item.getString(m_labelName);            
        }
        return s;
    }

    // ------------------------------------------------------------------------
    // Image Handling
    
    /**
     * Get the data field for image locations. The value stored
     * in the data field should be a URL, a file within the current classpath,
     * a file on the filesystem, or null for no image.
     * @return the data field for image locations, or null for no images
     */
    public String getImageField() {
        return m_imageName;
    }
    
    /**
     * Set the data field for image locations. The value stored
     * in the data field should be a URL, a file within the current classpath,
     * a file on the filesystem, or null for no image. If the
     * <code>imageField</code> parameter is null, no images at all will be
     * drawn.
     * @param imageField the data field for image locations, or null for
     * no images
     */
    public void setImageField(String imageField) {
        if ( imageField != null ) m_images = new ImageFactory();
        m_imageName = imageField;
    }
    
    /**
     * Sets the maximum image dimensions, used to control scaling of loaded
     * images. This scaling is enforced immediately upon loading of the image.
     * @param width the maximum width of images (-1 for no limit)
     * @param height the maximum height of images (-1 for no limit)
     */
    public void setMaxImageDimensions(int width, int height) {
        if ( m_images == null ) m_images = new ImageFactory();
        m_images.setMaxImageDimensions(width, height);
    }
    
    /**
     * Returns a location string for the image to draw. Subclasses can override 
     * this class to perform custom image selection beyond looking up the value
     * from a data field.
     * @param item the item for which to select an image to draw
     * @return the location string for the image to use, or null for no image
     */
    protected String getImageLocation(VisualItem item) {
        return item.canGetString(m_imageName)
                ? item.getString(m_imageName)
                : null;
    }
    
    /**
     * Get the image to include in the label for the given VisualItem.
     * @param item the item to get an image for
     * @return the image for the item, or null for no image
     */
    protected Image getImage(VisualItem item) {
        String imageLoc = getImageLocation(item);
        return ( imageLoc == null ? null : m_images.getImage(imageLoc) );
    }
    
    
    // ------------------------------------------------------------------------
    // Rendering
    
    private String computeTextDimensions(VisualItem item, String text,
                                         double size)
    {
        // put item font in temp member variable
        m_font = item.getFont();
        // scale the font as needed
        if ( size != 1 ) {
            m_font = FontLib.getFont(m_font.getName(), m_font.getStyle(),
                                     size*m_font.getSize());
        }
        
        FontMetrics fm = DEFAULT_GRAPHICS.getFontMetrics(m_font);
        StringBuffer str = null;
        
        // compute the number of lines and the maximum width
        int nlines = 1, w = 0, start = 0, end = text.indexOf(m_delim);
        m_textDim.width = 0;
        String line;
        for ( ; end >= 0; ++nlines ) {
            w = fm.stringWidth(line=text.substring(start,end));
            // abbreviate line as needed
            if ( m_maxTextWidth > -1 && w > m_maxTextWidth ) {
                if ( str == null )
                    str = new StringBuffer(text.substring(0,start));
                str.append(StringLib.abbreviate(line, fm, m_maxTextWidth));
                str.append(m_delim);
                w = m_maxTextWidth;
            } else if ( str != null ) {
                str.append(line).append(m_delim);
            }
            // update maximum width and substring indices
            m_textDim.width = Math.max(m_textDim.width, w);
            start = end+1;
            end = text.indexOf(m_delim, start);
        }
        w = fm.stringWidth(line=text.substring(start));
        // abbreviate line as needed
        if ( m_maxTextWidth > -1 && w > m_maxTextWidth ) {
            if ( str == null )
                str = new StringBuffer(text.substring(0,start));
            str.append(StringLib.abbreviate(line, fm, m_maxTextWidth));
            w = m_maxTextWidth;
        } else if ( str != null ) {
            str.append(line);
        }
        // update maximum width
        m_textDim.width = Math.max(m_textDim.width, w);
        
        // compute the text height
        m_textDim.height = fm.getHeight() * nlines;
        
        return str==null ? text : str.toString();
    }
    
    /**
     * @see prefuse.render.AbstractShapeRenderer#getRawShape(prefuse.visual.VisualItem)
     */
    protected Shape getRawShape(VisualItem item) {
        m_text = getText(item);
        Image  img  = getImage(item);
        double size = item.getSize();
        
        // get image dimensions
        double iw=0, ih=0;
        if ( img != null ) {
            ih = img.getHeight(null);
            iw = img.getWidth(null);    
        }
        
        // get text dimensions
        int tw=0, th=0;
        if ( m_text != null ) {
            m_text = computeTextDimensions(item, m_text, size);
            th = m_textDim.height;
            tw = m_textDim.width;   
        }
        
        // get bounding box dimensions
        double w=0, h=0;
        switch ( m_imagePos ) {
        case Constants.LEFT:
        case Constants.RIGHT:
            w = tw + size*(iw +2*m_horizBorder
                   + (tw>0 && iw>0 ? m_imageMargin : 0));
            h = Math.max(th, size*ih) + size*2*m_vertBorder;
            break;
        case Constants.TOP:
        case Constants.BOTTOM:
            w = Math.max(tw, size*iw) + size*2*m_horizBorder;
            h = th + size*(ih + 2*m_vertBorder
                   + (th>0 && ih>0 ? m_imageMargin : 0));
            break;
        default:
            throw new IllegalStateException(
                "Unrecognized image alignment setting.");
        }
        
        // get the top-left point, using the current alignment settings
        getAlignedPoint(m_pt, item, w, h, m_xAlign, m_yAlign);
        
        if ( m_bbox instanceof RoundRectangle2D ) {
            RoundRectangle2D rr = (RoundRectangle2D)m_bbox;
            rr.setRoundRect(m_pt.getX(), m_pt.getY(), w, h,
                            size*m_arcWidth, size*m_arcHeight);
        } else {
            m_bbox.setFrame(m_pt.getX(), m_pt.getY(), w, h);
        }                                                               
        return m_bbox;
    }
    
    /**
     * Helper method, which calculates the top-left co-ordinate of an item
     * given the item's alignment.
     */
    protected static void getAlignedPoint(Point2D p, VisualItem item, 
            double w, double h, int xAlign, int yAlign)
    {
        double x = item.getX(), y = item.getY();
        if ( Double.isNaN(x) || Double.isInfinite(x) )
            x = 0; // safety check
        if ( Double.isNaN(y) || Double.isInfinite(y) )
            y = 0; // safety check
        
        if ( xAlign == Constants.CENTER ) {
            x = x-(w/2);
        } else if ( xAlign == Constants.RIGHT ) {
            x = x-w;
        }
        if ( yAlign == Constants.CENTER ) {
            y = y-(h/2);
        } else if ( yAlign == Constants.BOTTOM ) {
            y = y-h;
        }
        p.setLocation(x,y);
    }
    
    /**
     * @see prefuse.render.Renderer#render(java.awt.Graphics2D, prefuse.visual.VisualItem)
     */
    public void render(Graphics2D g, VisualItem item) {
        RectangularShape shape = (RectangularShape)getShape(item);
        if ( shape == null ) return;
        
        // fill the shape, if requested
        int type = getRenderType(item);
        if ( type==RENDER_TYPE_FILL || type==RENDER_TYPE_DRAW_AND_FILL )
            GraphicsLib.paint(g, item, shape, getStroke(item), RENDER_TYPE_FILL);

        // now render the image and text
        String text = m_text;
        Image  img  = getImage(item);
        
        if ( text == null && img == null )
            return;
                        
        double size = item.getSize();
        boolean useInt = 1.5 > Math.max(g.getTransform().getScaleX(),
                                        g.getTransform().getScaleY());
        double x = shape.getMinX() + size*m_horizBorder;
        double y = shape.getMinY() + size*m_vertBorder;
        
        // render image
        if ( img != null ) {            
            double w = size * img.getWidth(null);
            double h = size * img.getHeight(null);
            double ix=x, iy=y;
            
            // determine one co-ordinate based on the image position
            switch ( m_imagePos ) {
            case Constants.LEFT:
                x += w + size*m_imageMargin;
                break;
            case Constants.RIGHT:
                ix = shape.getMaxX() - size*m_horizBorder - w;
                break;
            case Constants.TOP:
                y += h + size*m_imageMargin;
                break;
            case Constants.BOTTOM:
                iy = shape.getMaxY() - size*m_vertBorder - h;
                break;
            default:
                throw new IllegalStateException(
                        "Unrecognized image alignment setting.");
            }
            
            // determine the other coordinate based on image alignment
            switch ( m_imagePos ) {
            case Constants.LEFT:
            case Constants.RIGHT:
                // need to set image y-coordinate
                switch ( m_vImageAlign ) {
                case Constants.TOP:
                    break;
                case Constants.BOTTOM:
                    iy = shape.getMaxY() - size*m_vertBorder - h;
                    break;
                case Constants.CENTER:
                    iy = shape.getCenterY() - h/2;
                    break;
                }
                break;
            case Constants.TOP:
            case Constants.BOTTOM:
                // need to set image x-coordinate
                switch ( m_hImageAlign ) {
                case Constants.LEFT:
                    break;
                case Constants.RIGHT:
                    ix = shape.getMaxX() - size*m_horizBorder - w;
                    break;
                case Constants.CENTER:
                    ix = shape.getCenterX() - w/2;
                    break;
                }
                break;
            }
            
            if ( useInt && size == 1.0 ) {
                // if possible, use integer precision
                // results in faster, flicker-free image rendering
                g.drawImage(img, (int)ix, (int)iy, null);
            } else {
                m_transform.setTransform(size,0,0,size,ix,iy);
                g.drawImage(img, m_transform, null);
            }
        }
        
        // render text
        int textColor = item.getTextColor();
        if ( text != null && ColorLib.alpha(textColor) > 0 ) {
            g.setPaint(ColorLib.getColor(textColor));
            g.setFont(m_font);
            FontMetrics fm = DEFAULT_GRAPHICS.getFontMetrics(m_font);

            // compute available width
            double tw;
            switch ( m_imagePos ) {
            case Constants.TOP:
            case Constants.BOTTOM:
                tw = shape.getWidth() - 2*size*m_horizBorder;
                break;
            default:
                tw = m_textDim.width;
            }
            
            // compute available height
            double th;
            switch ( m_imagePos ) {
            case Constants.LEFT:
            case Constants.RIGHT:
                th = shape.getHeight() - 2*size*m_vertBorder;
                break;
            default:
                th = m_textDim.height;
            }
            
            // compute starting y-coordinate
            y += fm.getAscent();
            switch ( m_vTextAlign ) {
            case Constants.TOP:
                break;
            case Constants.BOTTOM:
                y += th - m_textDim.height;
                break;
            case Constants.CENTER:
                y += (th - m_textDim.height)/2;
            }
            
            // render each line of text
            int lh = fm.getHeight(); // the line height
            int start = 0, end = text.indexOf(m_delim);
            for ( ; end >= 0; y += lh ) {
                drawString(g, fm, text.substring(start, end), useInt, x, y, tw);
                start = end+1;
                end = text.indexOf(m_delim, start);   
            }
            drawString(g, fm, text.substring(start), useInt, x, y, tw);
        }
    
        // draw border
        if (type==RENDER_TYPE_DRAW || type==RENDER_TYPE_DRAW_AND_FILL) {
            GraphicsLib.paint(g,item,shape,getStroke(item),RENDER_TYPE_DRAW);
        }
    }
    
    private final void drawString(Graphics2D g, FontMetrics fm, String text,
            boolean useInt, double x, double y, double w)
    {
        // compute the x-coordinate
        double tx;
        switch ( m_hTextAlign ) {
        case Constants.LEFT:
            tx = x;
            break;
        case Constants.RIGHT:
            tx = x + w - fm.stringWidth(text);
            break;
        case Constants.CENTER:
            tx = x + (w - fm.stringWidth(text)) / 2;
            break;
        default:
            throw new IllegalStateException(
                    "Unrecognized text alignment setting.");
        }
        // use integer precision unless zoomed-in
        // results in more stable drawing
        if ( useInt ) {
            g.drawString(text, (int)tx, (int)y);
        } else {
            g.drawString(text, (float)tx, (float)y);
        }
    }
    
    /**
     * Returns the image factory used by this renderer.
     * @return the image factory
     */
    public ImageFactory getImageFactory() {
        if ( m_images == null ) m_images = new ImageFactory();
        return m_images;
    }
    
    /**
     * Sets the image factory used by this renderer.
     * @param ifact the image factory
     */
    public void setImageFactory(ImageFactory ifact) {
        m_images = ifact;
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Get the horizontal text alignment within the layout. One of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}. The default is centered text.
     * @return the horizontal text alignment
     */
    public int getHorizontalTextAlignment() {
        return m_hTextAlign;
    }
    
    /**
     * Set the horizontal text alignment within the layout. One of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}. The default is centered text.
     * @param halign the desired horizontal text alignment
     */
    public void setHorizontalTextAlignment(int halign) {
        if ( halign != Constants.LEFT &&
             halign != Constants.RIGHT &&
             halign != Constants.CENTER )
           throw new IllegalArgumentException(
                   "Illegal horizontal text alignment value.");
        m_hTextAlign = halign;
    }
    
    /**
     * Get the vertical text alignment within the layout. One of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}. The default is centered text.
     * @return the vertical text alignment
     */
    public int getVerticalTextAlignment() {
        return m_vTextAlign;
    }
    
    /**
     * Set the vertical text alignment within the layout. One of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}. The default is centered text.
     * @param valign the desired vertical text alignment
     */
    public void setVerticalTextAlignment(int valign) {
        if ( valign != Constants.TOP &&
             valign != Constants.BOTTOM &&
             valign != Constants.CENTER )
            throw new IllegalArgumentException(
                    "Illegal vertical text alignment value.");
        m_vTextAlign = valign;
    }
    
    /**
     * Get the horizontal image alignment within the layout. One of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}. The default is a centered image.
     * @return the horizontal image alignment
     */
    public int getHorizontalImageAlignment() {
        return m_hImageAlign;
    }
    
    /**
     * Set the horizontal image alignment within the layout. One of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}. The default is a centered image.
     * @param halign the desired horizontal image alignment
     */
    public void setHorizontalImageAlignment(int halign) {
        if ( halign != Constants.LEFT &&
             halign != Constants.RIGHT &&
             halign != Constants.CENTER )
           throw new IllegalArgumentException(
                   "Illegal horizontal text alignment value.");
        m_hImageAlign = halign;
    }
    
    /**
     * Get the vertical image alignment within the layout. One of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}. The default is a centered image.
     * @return the vertical image alignment
     */
    public int getVerticalImageAlignment() {
        return m_vImageAlign;
    }
    
    /**
     * Set the vertical image alignment within the layout. One of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}. The default is a centered image.
     * @param valign the desired vertical image alignment
     */
    public void setVerticalImageAlignment(int valign) {
        if ( valign != Constants.TOP &&
             valign != Constants.BOTTOM &&
             valign != Constants.CENTER )
            throw new IllegalArgumentException(
                    "Illegal vertical text alignment value.");
        m_vImageAlign = valign;
    }
    
    /**
     * Get the image position, determining where the image is placed with
     * respect to the text. One of {@link Constants#LEFT},
     * {@link Constants#RIGHT}, {@link Constants#TOP}, or
     * {@link Constants#BOTTOM}.  The default is left.
     * @return the image position
     */
    public int getImagePosition() {
        return m_imagePos;
    }
    
    /**
     * Set the image position, determining where the image is placed with
     * respect to the text. One of {@link Constants#LEFT},
     * {@link Constants#RIGHT}, {@link Constants#TOP}, or
     * {@link Constants#BOTTOM}.  The default is left.
     * @param pos the desired image position
     */
    public void setImagePosition(int pos) {
        if ( pos != Constants.TOP &&
             pos != Constants.BOTTOM &&
             pos != Constants.LEFT &&
             pos != Constants.RIGHT &&
             pos != Constants.CENTER )
           throw new IllegalArgumentException(
                   "Illegal image position value.");
        m_imagePos = pos;
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Get the horizontal alignment of this node with respect to its
     * x, y coordinates.
     * @return the horizontal alignment, one of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}.
     */
    public int getHorizontalAlignment() {
        return m_xAlign;
    }
    
    /**
     * Get the vertical alignment of this node with respect to its
     * x, y coordinates.
     * @return the vertical alignment, one of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}.
     */
    public int getVerticalAlignment() {
        return m_yAlign;
    }
    
    /**
     * Set the horizontal alignment of this node with respect to its
     * x, y coordinates.
     * @param align the horizontal alignment, one of
     * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
     * {@link prefuse.Constants#CENTER}.
     */ 
    public void setHorizontalAlignment(int align) {
        m_xAlign = align;
    }
    
    /**
     * Set the vertical alignment of this node with respect to its
     * x, y coordinates.
     * @param align the vertical alignment, one of
     * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
     * {@link prefuse.Constants#CENTER}.
     */ 
    public void setVerticalAlignment(int align) {
        m_yAlign = align;
    }
    
    /**
     * Returns the amount of padding in pixels between the content 
     * and the border of this item along the horizontal dimension.
     * @return the horizontal padding
     */
    public int getHorizontalPadding() {
        return m_horizBorder;
    }
    
    /**
     * Sets the amount of padding in pixels between the content 
     * and the border of this item along the horizontal dimension.
     * @param xpad the horizontal padding to set
     */
    public void setHorizontalPadding(int xpad) {
        m_horizBorder = xpad;
    }
    
    /**
     * Returns the amount of padding in pixels between the content 
     * and the border of this item along the vertical dimension.
     * @return the vertical padding
     */
    public int getVerticalPadding() {
        return m_vertBorder;
    }
    
    /**
     * Sets the amount of padding in pixels between the content 
     * and the border of this item along the vertical dimension.
     * @param ypad the vertical padding
     */
    public void setVerticalPadding(int ypad) {
        m_vertBorder = ypad;
    }
    
    /**
     * Get the padding, in pixels, between an image and text.
     * @return the padding between an image and text
     */
    public int getImageTextPadding() {
        return m_imageMargin;
    }
    
    /**
     * Set the padding, in pixels, between an image and text.
     * @param pad the padding to use between an image and text
     */
    public void setImageTextPadding(int pad) {
        m_imageMargin = pad;
    }
    
} // end of class LabelRenderer

package prefuse.render;

import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Arc2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RectangularShape;
import java.awt.geom.RoundRectangle2D;
import java.util.Iterator;

import prefuse.Constants;
import prefuse.data.Node;
import prefuse.util.ColorLib;
import prefuse.util.FontLib;
import prefuse.util.GraphicsLib;
import prefuse.util.StringLib;
import prefuse.visual.NodeItem;
import prefuse.visual.VisualItem;

/**
 * 渲染一个包含或文本或图片或兼有之的label标签 Renderer that draws a label, which consists of a
 * text string, an image, or both.
 * 
 * <p>
 * When created using the default constructor, the renderer attempts to use text
 * from the "label" field. To use a different field, use the appropriate
 * constructor or use the {@link #setTextField(String)} method. To perform
 * custom String selection, subclass this Renderer and override the
 * {@link #getText(VisualItem)} method. When the text field is <code>null</code>
 * , no text label will be shown. Labels can span multiple lines of text,
 * determined by the presence of newline characters ('\n') within the text
 * string.
 * </p>
 * 
 * <p>
 * By default, no image is shown. To show an image, the image field needs to be
 * set, either using the appropriate constructor or the
 * {@link #setImageField(String)} method. The value of the image field should be
 * a text string indicating the location of the image file to use. The string
 * should be either a URL, a file located on the current classpath, or a file on
 * the local filesystem. If found, the image will be managed internally by an
 * {@link ImageFactory} instance, which maintains a cache of loaded images.
 * </p>
 * 
 * <p>
 * The position of the image relative to text can be set using the
 * {@link #setImagePosition(int)} method. Images can be placed to the left,
 * right, above, or below the text. The horizontal and vertical alignments of
 * either the text or the image can be set explicitly using the appropriate
 * methods of this class (e.g., {@link #setHorizontalTextAlignment(int)}). By
 * default, both the text and images are centered along both the horizontal and
 * vertical directions.
 * </p>
 * 
 * @author <a href="http://jheer.org">jeffrey heer</a>
 */
public class LabelRenderer extends AbstractShapeRenderer {
	
	
	public static enum LabelShape{
		Rectangle2D,
		Arc2D
	}

	protected ImageFactory m_images = null;
	protected String m_delim = "\n";

	protected String m_labelName = "label";
	protected String m_imageName = null;

	protected int m_xAlign = Constants.CENTER;
	protected int m_yAlign = Constants.CENTER;
	protected int m_hTextAlign = Constants.CENTER;
	protected int m_vTextAlign = Constants.CENTER;
	protected int m_hImageAlign = Constants.CENTER;
	protected int m_vImageAlign = Constants.CENTER;
	protected int m_imagePos = Constants.LEFT;

	protected int m_horizBorder = 2;
	protected int m_vertBorder = 1;
	protected int m_imageMargin = 2;
	protected int m_arcWidth = 0;
	protected int m_arcHeight = 0;

	protected int m_maxTextWidth = -1;

	/** Transform used to scale and position images */
	AffineTransform m_transform = new AffineTransform();

	/** The holder for the currently computed bounding box */
	protected RectangularShape m_bbox = new Rectangle2D.Double(); // Prefuse框架自带的，即默认使用矩形
	protected Point2D m_pt = new Point2D.Double(); // temp point
	protected Font m_font; // temp font holder
	protected String m_text; // label text
	protected Dimension m_textDim = new Dimension(); // text width / height

	/**
	 * Create a new LabelRenderer. By default the field "label" is used as the
	 * field name for looking up text, and no image is used.
	 */
	public LabelRenderer() {
	}

	/**
	 * Create a new LabelRenderer. Draws a text label using the given text data
	 * field and does not draw an image.
	 * 
	 * @param textField
	 *            the data field for the text label.
	 */
	public LabelRenderer(String textField) {
		this.setTextField(textField);
	}

	/**
	 * 
	 * @param textField
	 * @param isRectangle
	 *            true-矩形 false-圆形
	 */
	public LabelRenderer(String textField, LabelShape shape) {
		if (shape == LabelShape.Rectangle2D) {
			m_bbox = new Rectangle2D.Double();
		} else {
			m_bbox = new Arc2D.Double();
		}
		this.setTextField(textField);
	}

	/**
	 * Create a new LabelRenderer. Draws a text label using the given text data
	 * field, and draws the image at the location reported by the given image
	 * data field.
	 * 
	 * @param textField
	 *            the data field for the text label
	 * @param imageField
	 *            the data field for the image location. This value in the data
	 *            field should be a URL, a file within the current classpath, a
	 *            file on the filesystem, or null for no image. If the
	 *            <code>imageField</code> parameter is null, no images at all
	 *            will be drawn.
	 */
	public LabelRenderer(String textField, String imageField) {
		setTextField(textField);
		setImageField(imageField);
	}

	// ------------------------------------------------------------------------

	/**
	 * Rounds the corners of the bounding rectangle in which the text string is
	 * rendered. This will only be seen if either the stroke or fill color is
	 * non-transparent.
	 * 
	 * @param arcWidth
	 *            the width of the curved corner
	 * @param arcHeight
	 *            the height of the curved corner
	 */
	public void setRoundedCorner(int arcWidth, int arcHeight) {
		if ((arcWidth == 0 || arcHeight == 0) && !(m_bbox instanceof Rectangle2D)) {
			m_bbox = new Rectangle2D.Double();
		} else {
			if (!(m_bbox instanceof RoundRectangle2D))
				m_bbox = new RoundRectangle2D.Double();
			((RoundRectangle2D) m_bbox).setRoundRect(0, 0, 10, 10, arcWidth, arcHeight);
			m_arcWidth = arcWidth;
			m_arcHeight = arcHeight;
		}
	}

	/**
	 * Get the field name to use for text labels.
	 * 
	 * @return the data field for text labels, or null for no text
	 */
	public String getTextField() {
		return m_labelName;
	}

	/**
	 * Set the field name to use for text labels.
	 * 
	 * @param textField
	 *            the data field for text labels, or null for no text
	 */
	public void setTextField(String textField) {
		m_labelName = textField;
	}

	/**
	 * Sets the maximum width that should be allowed of the text label. A value
	 * of -1 specifies no limit (this is the default).
	 * 
	 * @param maxWidth
	 *            the maximum width of the text or -1 for no limit
	 */
	public void setMaxTextWidth(int maxWidth) {
		m_maxTextWidth = maxWidth;
	}

	/**
	 * Returns the text to draw. Subclasses can override this class to perform
	 * custom text selection.
	 * 
	 * @param item
	 *            the item to represent as a <code>String</code>
	 * @return a <code>String</code> to draw
	 */
	protected String getText(VisualItem item) {
		String s = null;
		if (item.canGetString(m_labelName)) {
			return item.getString(m_labelName);
		}
		return s;
	}

	// ------------------------------------------------------------------------
	// Image Handling

	/**
	 * Get the data field for image locations. The value stored in the data
	 * field should be a URL, a file within the current classpath, a file on the
	 * filesystem, or null for no image.
	 * 
	 * @return the data field for image locations, or null for no images
	 */
	public String getImageField() {
		return m_imageName;
	}

	/**
	 * Set the data field for image locations. The value stored in the data
	 * field should be a URL, a file within the current classpath, a file on the
	 * filesystem, or null for no image. If the <code>imageField</code>
	 * parameter is null, no images at all will be drawn.
	 * 
	 * @param imageField
	 *            the data field for image locations, or null for no images
	 */
	public void setImageField(String imageField) {
		if (imageField != null)
			m_images = new ImageFactory();
		m_imageName = imageField;
	}

	/**
	 * Sets the maximum image dimensions, used to control scaling of loaded
	 * images. This scaling is enforced immediately upon loading of the image.
	 * 
	 * @param width
	 *            the maximum width of images (-1 for no limit)
	 * @param height
	 *            the maximum height of images (-1 for no limit)
	 */
	public void setMaxImageDimensions(int width, int height) {
		if (m_images == null)
			m_images = new ImageFactory();
		m_images.setMaxImageDimensions(width, height);
	}

	/**
	 * Returns a location string for the image to draw. Subclasses can override
	 * this class to perform custom image selection beyond looking up the value
	 * from a data field.
	 * 
	 * @param item
	 *            the item for which to select an image to draw
	 * @return the location string for the image to use, or null for no image
	 */
	protected String getImageLocation(VisualItem item) {
		return item.canGetString(m_imageName) ? item.getString(m_imageName) : null;
	}

	/**
	 * Get the image to include in the label for the given VisualItem.
	 * 
	 * @param item
	 *            the item to get an image for
	 * @return the image for the item, or null for no image
	 */
	protected Image getImage(VisualItem item) {
		String imageLoc = getImageLocation(item);
		return (imageLoc == null ? null : m_images.getImage(imageLoc));
	}

	// ------------------------------------------------------------------------
	// Rendering

	private String computeTextDimensions(VisualItem item, String text, double size) {
		// put item font in temp member variable
		m_font = item.getFont();
		// scale the font as needed
		if (size != 1) {
			m_font = FontLib.getFont(m_font.getName(), m_font.getStyle(), size * m_font.getSize());
		}

		FontMetrics fm = DEFAULT_GRAPHICS.getFontMetrics(m_font);
		StringBuffer str = null;

		// compute the number of lines and the maximum width
		int nlines = 1, w = 0, start = 0, end = text.indexOf(m_delim);
		m_textDim.width = 0;
		String line;
		for (; end >= 0; ++nlines) {
			w = fm.stringWidth(line = text.substring(start, end));
			// abbreviate line as needed
			if (m_maxTextWidth > -1 && w > m_maxTextWidth) {
				if (str == null)
					str = new StringBuffer(text.substring(0, start));
				str.append(StringLib.abbreviate(line, fm, m_maxTextWidth));
				str.append(m_delim);
				w = m_maxTextWidth;
			} else if (str != null) {
				str.append(line).append(m_delim);
			}
			// update maximum width and substring indices
			m_textDim.width = Math.max(m_textDim.width, w);
			start = end + 1;
			end = text.indexOf(m_delim, start);
		}
		w = fm.stringWidth(line = text.substring(start));
		// abbreviate line as needed
		if (m_maxTextWidth > -1 && w > m_maxTextWidth) {
			if (str == null)
				str = new StringBuffer(text.substring(0, start));
			str.append(StringLib.abbreviate(line, fm, m_maxTextWidth));
			w = m_maxTextWidth;
		} else if (str != null) {
			str.append(line);
		}
		// update maximum width
		m_textDim.width = Math.max(m_textDim.width, w);

		// compute the text height
		m_textDim.height = fm.getHeight() * nlines;

		return str == null ? text : str.toString();
	}

	/**
	 * @see prefuse.render.AbstractShapeRenderer#getRawShape(prefuse.visual.VisualItem)
	 */
	protected Shape getRawShape(VisualItem item) {
		
		m_text = getText(item);
        Image  img  = getImage(item);
        double size = item.getSize();
        
        // get image dimensions
        double iw=0, ih=0;
        if ( img != null ) {
            ih = img.getHeight(null);
            iw = img.getWidth(null);    
        }
        
        // get text dimensions
        int tw=0, th=0;
        if ( m_text != null ) {
            m_text = computeTextDimensions(item, m_text, size);
            th = m_textDim.height;
            tw = m_textDim.width;   
        }
        
        // get bounding box dimensions
        double w=0, h=0;
        switch ( m_imagePos ) {
        case Constants.LEFT:
        case Constants.RIGHT:
            w = tw + size*(iw +2*m_horizBorder
                   + (tw>0 && iw>0 ? m_imageMargin : 0));
            h = Math.max(th, size*ih) + size*2*m_vertBorder;
            break;
        case Constants.TOP:
        case Constants.BOTTOM:
            w = Math.max(tw, size*iw) + size*2*m_horizBorder;
            h = th + size*(ih + 2*m_vertBorder
                   + (th>0 && ih>0 ? m_imageMargin : 0));
            break;
        default:
            throw new IllegalStateException(
                "Unrecognized image alignment setting.");
        }
        
        // get the top-left point, using the current alignment settings
        getAlignedPoint(m_pt, item, w, h, m_xAlign, m_yAlign);

		if (m_bbox instanceof RoundRectangle2D) {// 圆角矩形
			RoundRectangle2D rr = (RoundRectangle2D) m_bbox;
			rr.setRoundRect(m_pt.getX(), m_pt.getY(), w, h, size * m_arcWidth, size * m_arcHeight);
		} else if (m_bbox instanceof Arc2D) {// 圆形
			Arc2D rr = (Arc2D) m_bbox;
			rr.setArc(m_pt.getX(), m_pt.getY(), w, w, 360, 360, Arc2D.OPEN);
		} else {
			m_bbox.setFrame(m_pt.getX(), m_pt.getY(), w, h);// 矩形
		} 
		return m_bbox;
	}

	/**
	 * Helper method, which calculates the top-left co-ordinate of an item given
	 * the item's alignment.
	 */
	protected static void getAlignedPoint(Point2D p, VisualItem item, double w, double h, int xAlign, int yAlign) {
		double x = item.getX(), y = item.getY();
		if (Double.isNaN(x) || Double.isInfinite(x))
			x = 0; // safety check
		if (Double.isNaN(y) || Double.isInfinite(y))
			y = 0; // safety check

		if (xAlign == Constants.CENTER) {
			x = x - (w / 2);
		} else if (xAlign == Constants.RIGHT) {
			x = x - w;
		}
		if (yAlign == Constants.CENTER) {
			y = y - (h / 2);
		} else if (yAlign == Constants.BOTTOM) {
			y = y - h;
		}
		p.setLocation(x, y);
	}

	/**
	 * @see prefuse.render.Renderer#render(java.awt.Graphics2D,
	 *      prefuse.visual.VisualItem)
	 */
	public void render(Graphics2D g, VisualItem item) {
		RectangularShape shape = (RectangularShape) getShape(item);
		if (shape == null)
			return;

		// fill the shape, if requested
		int type = getRenderType(item);
		if (type == RENDER_TYPE_FILL || type == RENDER_TYPE_DRAW_AND_FILL)
			GraphicsLib.paint(g, item, shape, getStroke(item), RENDER_TYPE_FILL);

		// now render the image and text
		String text = m_text;
		Image img = getImage(item);

		if (text == null && img == null)
			return;

		double size = item.getSize();
		boolean useInt = 1.5 > Math.max(g.getTransform().getScaleX(), g.getTransform().getScaleY());
		double x = shape.getMinX() + size * m_horizBorder;
		double y = shape.getMinY() + size * m_vertBorder;

		// render image
		if (img != null) {
			double w = size * img.getWidth(null);
			double h = size * img.getHeight(null);
			double ix = x, iy = y;

			// determine one co-ordinate based on the image position
			switch (m_imagePos) {
			case Constants.LEFT:
				x += w + size * m_imageMargin;
				break;
			case Constants.RIGHT:
				ix = shape.getMaxX() - size * m_horizBorder - w;
				break;
			case Constants.TOP:
				y += h + size * m_imageMargin;
				break;
			case Constants.BOTTOM:
				iy = shape.getMaxY() - size * m_vertBorder - h;
				break;
			default:
				throw new IllegalStateException("Unrecognized image alignment setting.");
			}

			// determine the other coordinate based on image alignment
			switch (m_imagePos) {
			case Constants.LEFT:
			case Constants.RIGHT:
				// need to set image y-coordinate
				switch (m_vImageAlign) {
				case Constants.TOP:
					break;
				case Constants.BOTTOM:
					iy = shape.getMaxY() - size * m_vertBorder - h;
					break;
				case Constants.CENTER:
					iy = shape.getCenterY() - h / 2;
					break;
				}
				break;
			case Constants.TOP:
			case Constants.BOTTOM:
				// need to set image x-coordinate
				switch (m_hImageAlign) {
				case Constants.LEFT:
					break;
				case Constants.RIGHT:
					ix = shape.getMaxX() - size * m_horizBorder - w;
					break;
				case Constants.CENTER:
					ix = shape.getCenterX() - w / 2;
					break;
				}
				break;
			}

			if (useInt && size == 1.0) {
				// if possible, use integer precision
				// results in faster, flicker-free image rendering
				g.drawImage(img, (int) ix, (int) iy, null);
			} else {
				m_transform.setTransform(size, 0, 0, size, ix, iy);
				g.drawImage(img, m_transform, null);
			}
		}

		// render text
		int textColor = item.getTextColor();
		if (text != null && ColorLib.alpha(textColor) > 0) {
			g.setPaint(ColorLib.getColor(textColor));
			g.setFont(m_font);
			FontMetrics fm = DEFAULT_GRAPHICS.getFontMetrics(m_font);

			// compute available width
			double tw;
			switch (m_imagePos) {
			case Constants.TOP:
			case Constants.BOTTOM:
				tw = shape.getWidth() - 2 * size * m_horizBorder;
				break;
			default:
				tw = m_textDim.width;
			}

			// compute available height
			double th;
			switch (m_imagePos) {
			case Constants.LEFT:
			case Constants.RIGHT:
				th = shape.getHeight() - 2 * size * m_vertBorder;
				break;
			default:
				th = m_textDim.height;
			}

			// compute starting y-coordinate
			y += fm.getAscent();
			switch (m_vTextAlign) {
			case Constants.TOP:
				break;
			case Constants.BOTTOM:
				y += th - m_textDim.height;
				break;
			case Constants.CENTER:
				y += (th - m_textDim.height) / 2;
			}

			// render each line of text
			int lh = fm.getHeight(); // the line height
			int start = 0, end = text.indexOf(m_delim);
			for (; end >= 0; y += lh) {
				drawString(g, fm, text.substring(start, end), useInt, x, y, tw);
				start = end + 1;
				end = text.indexOf(m_delim, start);
			}
			drawString(g, fm, text.substring(start), useInt, x, y, tw);
		}

		// draw border
		if (type == RENDER_TYPE_DRAW || type == RENDER_TYPE_DRAW_AND_FILL) {
			GraphicsLib.paint(g, item, shape, getStroke(item), RENDER_TYPE_DRAW);
		}
	}

	private final void drawString(Graphics2D g, FontMetrics fm, String text, boolean useInt, double x, double y, double w) {
		// compute the x-coordinate
		double tx;
		switch (m_hTextAlign) {
		case Constants.LEFT:
			tx = x;
			break;
		case Constants.RIGHT:
			tx = x + w - fm.stringWidth(text);
			break;
		case Constants.CENTER:
			tx = x + (w - fm.stringWidth(text)) / 2;
			break;
		default:
			throw new IllegalStateException("Unrecognized text alignment setting.");
		}
		// use integer precision unless zoomed-in
		// results in more stable drawing
		if (useInt) {
			g.drawString(text, (int) tx, (int) y);
		} else {
			g.drawString(text, (float) tx, (float) y);
		}
	}

	/**
	 * Returns the image factory used by this renderer.
	 * 
	 * @return the image factory
	 */
	public ImageFactory getImageFactory() {
		if (m_images == null)
			m_images = new ImageFactory();
		return m_images;
	}

	/**
	 * Sets the image factory used by this renderer.
	 * 
	 * @param ifact
	 *            the image factory
	 */
	public void setImageFactory(ImageFactory ifact) {
		m_images = ifact;
	}

	// ------------------------------------------------------------------------

	/**
	 * Get the horizontal text alignment within the layout. One of
	 * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
	 * {@link prefuse.Constants#CENTER}. The default is centered text.
	 * 
	 * @return the horizontal text alignment
	 */
	public int getHorizontalTextAlignment() {
		return m_hTextAlign;
	}

	/**
	 * Set the horizontal text alignment within the layout. One of
	 * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
	 * {@link prefuse.Constants#CENTER}. The default is centered text.
	 * 
	 * @param halign
	 *            the desired horizontal text alignment
	 */
	public void setHorizontalTextAlignment(int halign) {
		if (halign != Constants.LEFT && halign != Constants.RIGHT && halign != Constants.CENTER)
			throw new IllegalArgumentException("Illegal horizontal text alignment value.");
		m_hTextAlign = halign;
	}

	/**
	 * Get the vertical text alignment within the layout. One of
	 * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
	 * {@link prefuse.Constants#CENTER}. The default is centered text.
	 * 
	 * @return the vertical text alignment
	 */
	public int getVerticalTextAlignment() {
		return m_vTextAlign;
	}

	/**
	 * Set the vertical text alignment within the layout. One of
	 * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
	 * {@link prefuse.Constants#CENTER}. The default is centered text.
	 * 
	 * @param valign
	 *            the desired vertical text alignment
	 */
	public void setVerticalTextAlignment(int valign) {
		if (valign != Constants.TOP && valign != Constants.BOTTOM && valign != Constants.CENTER)
			throw new IllegalArgumentException("Illegal vertical text alignment value.");
		m_vTextAlign = valign;
	}

	/**
	 * Get the horizontal image alignment within the layout. One of
	 * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
	 * {@link prefuse.Constants#CENTER}. The default is a centered image.
	 * 
	 * @return the horizontal image alignment
	 */
	public int getHorizontalImageAlignment() {
		return m_hImageAlign;
	}

	/**
	 * Set the horizontal image alignment within the layout. One of
	 * {@link prefuse.Constants#LEFT}, {@link prefuse.Constants#RIGHT}, or
	 * {@link prefuse.Constants#CENTER}. The default is a centered image.
	 * 
	 * @param halign
	 *            the desired horizontal image alignment
	 */
	public void setHorizontalImageAlignment(int halign) {
		if (halign != Constants.LEFT && halign != Constants.RIGHT && halign != Constants.CENTER)
			throw new IllegalArgumentException("Illegal horizontal text alignment value.");
		m_hImageAlign = halign;
	}

	/**
	 * Get the vertical image alignment within the layout. One of
	 * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
	 * {@link prefuse.Constants#CENTER}. The default is a centered image.
	 * 
	 * @return the vertical image alignment
	 */
	public int getVerticalImageAlignment() {
		return m_vImageAlign;
	}

	/**
	 * Set the vertical image alignment within the layout. One of
	 * {@link prefuse.Constants#TOP}, {@link prefuse.Constants#BOTTOM}, or
	 * {@link prefuse.Constants#CENTER}. The default is a centered image.
	 * 
	 * @param valign
	 *            the desired vertical image alignment
	 */
	public void setVerticalImageAlignment(int valign) {
		if (valign != Constants.TOP && valign != Constants.BOTTOM && valign != Constants.CENTER)
			throw new IllegalArgumentException("Illegal vertical text alignment value.");
		m_vImageAlign = valign;
	}

	/**
	 * Get the image position, determining where the image is placed with
	 * respect to the text. One of {@link Constants#LEFT},
	 * {@link Constants#RIGHT}, {@link Constants#TOP}, or
	 * {@link Constants#BOTTOM}. The default is left.
	 * 
	 * @return the image position
	 */
	public int getImagePosition() {
		return m_imagePos;
	}

	/**
	 * Set the image position, determining where the image is placed with
	 * respect to the text. One of {@link Constants#LEFT},
	 * {@link Constants#RIGHT}, {@link Constants#TOP}, or
	 * {@link Constants#BOTTOM}. The default is left.
	 * 
	 * @param pos
	 *            the desired image position
	 */
	public void setImagePosition(int pos) {
		if (pos != Constants.TOP && pos != Constants.BOTTOM && pos != Constants.LEFT && pos != Constants.RIGHT && pos != Constants.CENTER)
			throw new IllegalArgumentException("Illegal image position value.");
		m_imagePos = pos;
	}

	// ------------------------------------------------------------------------

	/**
	 * Get the horizontal alignment of this node with respect to its x, y
	 * coordinates.
	 * 
	 * @return the horizontal alignment, one of {@link prefuse.Constants#LEFT},
	 *         {@link prefuse.Constants#RIGHT}, or
	 *         {@link prefuse.Constants#CENTER}.
	 */
	public int getHorizontalAlignment() {
		return m_xAlign;
	}

	/**
	 * Get the vertical alignment of this node with respect to its x, y
	 * coordinates.
	 * 
	 * @return the vertical alignment, one of {@link prefuse.Constants#TOP},
	 *         {@link prefuse.Constants#BOTTOM}, or
	 *         {@link prefuse.Constants#CENTER}.
	 */
	public int getVerticalAlignment() {
		return m_yAlign;
	}

	/**
	 * Set the horizontal alignment of this node with respect to its x, y
	 * coordinates.
	 * 
	 * @param align
	 *            the horizontal alignment, one of
	 *            {@link prefuse.Constants#LEFT},
	 *            {@link prefuse.Constants#RIGHT}, or
	 *            {@link prefuse.Constants#CENTER}.
	 */
	public void setHorizontalAlignment(int align) {
		m_xAlign = align;
	}

	/**
	 * Set the vertical alignment of this node with respect to its x, y
	 * coordinates.
	 * 
	 * @param align
	 *            the vertical alignment, one of {@link prefuse.Constants#TOP},
	 *            {@link prefuse.Constants#BOTTOM}, or
	 *            {@link prefuse.Constants#CENTER}.
	 */
	public void setVerticalAlignment(int align) {
		m_yAlign = align;
	}

	/**
	 * Returns the amount of padding in pixels between the content and the
	 * border of this item along the horizontal dimension.
	 * 
	 * @return the horizontal padding
	 */
	public int getHorizontalPadding() {
		return m_horizBorder;
	}

	/**
	 * Sets the amount of padding in pixels between the content and the border
	 * of this item along the horizontal dimension.
	 * 
	 * @param xpad
	 *            the horizontal padding to set
	 */
	public void setHorizontalPadding(int xpad) {
		m_horizBorder = xpad;
	}

	/**
	 * Returns the amount of padding in pixels between the content and the
	 * border of this item along the vertical dimension.
	 * 
	 * @return the vertical padding
	 */
	public int getVerticalPadding() {
		return m_vertBorder;
	}

	/**
	 * Sets the amount of padding in pixels between the content and the border
	 * of this item along the vertical dimension.
	 * 
	 * @param ypad
	 *            the vertical padding
	 */
	public void setVerticalPadding(int ypad) {
		m_vertBorder = ypad;
	}

	/**
	 * Get the padding, in pixels, between an image and text.
	 * 
	 * @return the padding between an image and text
	 */
	public int getImageTextPadding() {
		return m_imageMargin;
	}

	/**
	 * Set the padding, in pixels, between an image and text.
	 * 
	 * @param pad
	 *            the padding to use between an image and text
	 */
	public void setImageTextPadding(int pad) {
		m_imageMargin = pad;
	}

} // end of class LabelRenderer

private static Visualization visInstance;

public static Visualization getVisualization(){
		if(visInstance == null){
			visInstance = new Visualization();
		}
		return visInstance;
}