Custom HTML tags in JTextPane

Question

Hi all,
I have seen this topic broached before but, in spite of many hours searching, haven't found the answer I'm looking for...
I jave a JTextPane containing an HTMLDocument and want to render elements within my own custom tag 'Custom' outlined in red.
I have subclassed HTMLEditorKit as follows:import javax.swing.text.ViewFactory;
import javax.swing.text.html.HTMLEditorKit;
public class HTMLEditorKitForCustom extends HTMLEditorKit{
     public ViewFactory getViewFactory(){
          return htmlFactoryForCustom;
    private static final ViewFactory htmlFactoryForCustom = new HTMLFactoryForCustom();
}I have subclassed HTMLEditorKit.HTMLFactory as follows:import javax.swing.text.View;
import javax.swing.text.Element;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.StyleConstants;
public class HTMLFactoryForCustom extends HTMLEditorKit.HTMLFactory{
     public View create(Element element){
          Object object = element.getAttributes().getAttribute(StyleConstants.NameAttribute);
          if(CustomView.CUSTOM_KEY_TAG.equals(object)){
               return new CustomView(element);
          return super.create(element);
}And, I have subclassed LabelView as follows:public class CustomView extends LabelView{
     public CustomView(Element element){
          super(element);
     public void paint(Graphics g, Shape a){
          super.paint(g, a);
          Rectangle rectangle = a instanceof Rectangle ? (Rectangle)a : a.getBounds();
          Graphics2D g2d = (Graphics2D)g;
          g.setColor(Color.RED);
          g.drawRect(rectangle.x, rectangle.y, rectangle.width, rectangle.height);
     public static final String CUSTOM_KEY_TAG = "Custom";
     public static final String CUSTOM_TYPE_TAG = "ccVarType";
     public static final String CUSTOM_NUMERIC_TYPE_TAG_VALUE = "Numeric";
}The JTextPane in question has its EditorKit set to my HTMLEditorKitForCustom throughtextPane.setEditorKit(new HTMLEditorKitForCustom();In combination, these classes ensure that when a <Custom>...</Custom> set of tags is encountered, the text between is rendered with a red outline.
This works fine when the custom tags and text are inserted but, as soon as a change is made that affects the paragraph containing the custom tags (for example, change alignment, font size, etc.), the content disappears. However, the underlying HTML still shows the <Custom> tag, but with no closing tag and without the text the tags once contained.
E.g. <Custom>Fred</Custom> becomes simply <Custom>.
Any help in solving this problem will be greatly appreciated!
Chris.

Answer 1

Stas, thanks for your response!
I did try registering the tag, and associating it with a SpecialAction then with a CharacterAction (I want the user to be able to change the font style, etc. of these Custom items).
I did this by creating HTMLDocumentForCustom (original name, huh!), subclassing HTMLDocument and inner HTMLReaderForCustom:// (Within HTMLDocumentForCustom)
public class HTMLReaderForCustom extends HTMLReader{
  public HTMLReaderForCustom(int pos){
    super(pos, 0, 0, null);
    registerTag(new HTML.UnknownTag(CustomView.CUSTOM_KEY_TAG), new SpecialAction());
}Then I created a new HTMLDocumentForCustom and did textPane.setDocument(document). Now, when I inserted the text between Custom tags, I got this exception:javax.swing.text.BadLocationException: Invalid insert;
     at javax.swing.text.GapContent.insertString(GapContent.java:109);
     at javax.swing.text.AbstractDocument.handleInsertString(AbstractDocument.java:722);I was using the following code to insert the text:SimpleAttributeSet attributes = new SimpleAttributeSet();
attributes.addAttribute(StyleConstants.NameAttribute, CustomView.CUSTOM_KEY_TAG);
try{
  document.insertString(1, "Custom Here!", attributes);
catch(BadLocationException ble){
  ble.printStackTrace();
}Inserting at position 1 was working fine before trying to subclass HTMLDocument and HTMLReader, and there's already text in the document before trying the insert -- in fact it didn't matter what the insert location was set to, the exception kept occurring.
Can you see anything obvious I've missed or am I barking totally up the wrong tree?
Chris.