JTextPane/HTMLEditorKit - Custom Comment View

Question

Hello.
Here's what I want to do... I want to be able to make hidden COMMENT tags visible in an uneditable JTextPane using an HTMLEditorKit. I went as far as installing my own ViewFactory, but comment elements are treated a little differently (noted by viewing HTMLDocument.dump(System.out)).
If anyone has a decent way to make comments like <!--this--> visible at will in the JTextPane using custom Views, or whatever, you have yourself 10 Duke Dollars. By the way... I'm advanced in Swing development, but the text package is very complex and intimidating.
- John

Answer 1

this is an example of using ViewFactory... it creates JEditorPane with line numbering.
You can see how ViewFactory works. Document represents tree structure of Elements ViewFactory produces appropriate Views for each Element. You have to specify required Element and generate View for it.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.text.rtf.*;
class Test extends JFrame
public Test()
super("Test");
JEditorPane edit = new JEditorPane();
edit.setEditorKit(new MyRTFEditorKit());
edit.setEditable(true);
JScrollPane scroll=new JScrollPane(edit);
getContentPane().add(scroll);
setSize(300,300);
setVisible(true);
public static void main(String a[])
new Test();
class MyRTFEditorKit extends RTFEditorKit
public ViewFactory getViewFactory()
return new MyRTFViewFactory();
class MyRTFViewFactory implements ViewFactory
public View create(Element elem)
String kind = elem.getName();
if (kind != null)
if (kind.equals(AbstractDocument.ContentElementName)) {
return new LabelView(elem);
} else if (kind.equals(AbstractDocument.ParagraphElementName)) {
// return new ParagraphView(elem);
return new MyParagraphView(elem);
} else if (kind.equals(AbstractDocument.SectionElementName)) {
// return new BoxView(elem, View.Y_AXIS);
return new MySectionView(elem, View.Y_AXIS);
} else if (kind.equals(StyleConstants.ComponentElementName)) {
return new ComponentView(elem);
} else if (kind.equals(StyleConstants.IconElementName)) {
return new IconView(elem);
// default to text display
return new LabelView(elem);
class MySectionView extends BoxView {
public MySectionView(Element e, int axis)
super(e,axis);
public void paintChild(Graphics g,Rectangle r,int n) {
if (n>0) {
MyParagraphView child=(MyParagraphView)this.getView(n-1);
int shift=child.shift+child.childCount;
MyParagraphView current=(MyParagraphView)this.getView(n);
current.shift=shift;
super.paintChild(g,r,n);
class MyParagraphView extends javax.swing.text.ParagraphView
public int childCount;
public int shift=0;
public MyParagraphView(Element e)
super(e);
short top=0;
short left=20;
short bottom=0;
short right=0;
this.setInsets(top,left,bottom,right);
public void paint(Graphics g, Shape a)
childCount=this.getViewCount();
super.paint (g,a);
int rowCountInThisParagraph=this.getViewCount(); //<----- YOU HAVE REAL ROW COUNT FOR ONE PARAGRAPH}
System.err.println(rowCountInThisParagraph);
public void paintChild(Graphics g,Rectangle r,int n) {
super.paintChild(g,r,n);
g.drawString(Integer.toString(shift+n+1),r.x-20,r.y+r.height-3);
best regards
Stas