How to implement custom view of certain elements in a JTextPane?

Question

Hi. I'm writing an application with a JTextPane in which I want to allow a style or attribute to be added to an (arbitrary) span of text, which will then result in a rectangle being drawn around that span of text. But I'm not sure how to do this.
I figure it will be necessary to extend one of the subclasses of View, but I'm not sure how to work that into my Document. Will I have to create a custom ViewFactory, or a custom EditorKit? Not sure I'd know how to do that.
Any pointers would be much appreciated.
Cheers,
Gregory

Answer 1

Here's the version I came up with. For some reason the width and height parameter of the two methods have a slightly different meaning which through me off for a while. Seems silly to me. Anyway it appears to work now:
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class RectangleHighlighter extends DefaultHighlighter.DefaultHighlightPainter
    public RectangleHighlighter(Color color)
        super( color );
    public Shape paintLayer(Graphics g, int offs0, int offs1,
        Shape bounds, JTextComponent c, View view)
        Color color = getColor();
        if (color == null)
            g.setColor(c.getSelectionColor());
        else
            g.setColor(color);
        if (offs0 == view.getStartOffset() && offs1 == view.getEndOffset())
            // Contained in view, can just use bounds.
            Rectangle alloc;
            if (bounds instanceof Rectangle)
                alloc = (Rectangle)bounds;
            else
                alloc = bounds.getBounds();
//            g.fillRect(alloc.x, alloc.y, alloc.width, alloc.height);
            g.drawRect(alloc.x, alloc.y, alloc.width - 1, alloc.height - 1);
            return alloc;
        else
            // Should only render part of View.
            try
                // --- determine locations ---
                Shape shape = view.modelToView(
                    offs0, Position.Bias.Forward, offs1,Position.Bias.Backward, bounds);
                Rectangle r = (shape instanceof Rectangle)
                    ? (Rectangle)shape : shape.getBounds();
//                g.fillRect(r.x, r.y, r.width, r.height);
                g.drawRect(r.x, r.y, r.width - 1, r.height - 1);
                return r;
            catch (BadLocationException e)
                // can't render
        // Only if exception
        return null;
    public static void main(String[] args)
        JTextPane textPane = new JTextPane();
        textPane.setText( "one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\n" );
        JScrollPane scrollPane = new JScrollPane( textPane );
        //  Highlight some text
        RectangleHighlighter cyan = new RectangleHighlighter( Color.CYAN );
        RectangleHighlighter red = new RectangleHighlighter( Color.RED );
        try
            textPane.getHighlighter().addHighlight( 8, 14, cyan );
            textPane.getHighlighter().addHighlight( 19, 24, red );
        catch(BadLocationException ble) {}
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        frame.getContentPane().add( scrollPane );
        frame.setSize(300, 200);
        frame.setVisible(true);
}