Package javax.swing.text.html

Source Code of javax.swing.text.html.HTMLEditorKit$LinkController

/*
* @(#)HTMLEditorKit.java  1.136 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.text.html;

import java.lang.reflect.Method;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.text.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;
import javax.swing.plaf.TextUI;
import java.util.*;
import javax.accessibility.*;
import java.lang.ref.*;

/**
* The Swing JEditorPane text component supports different kinds
* of content via a plug-in mechanism called an EditorKit.  Because
* HTML is a very popular format of content, some support is provided
* by default.  The default support is provided by this class, which
* supports HTML version 3.2 (with some extensions), and is migrating
* toward version 4.0.
* The <applet> tag is not supported, but some support is provided
* for the <object> tag.
* <p>
* There are several goals of the HTML EditorKit provided, that have
* an effect upon the way that HTML is modeled.  These
* have influenced its design in a substantial way. 
* <dl>
* <p>
* <dt>
* Support editing
* <dd>
* It might seem fairly obvious that a plug-in for JEditorPane
* should provide editing support, but that fact has several
* design considerations.  There are a substantial number of HTML
* documents that don't properly conform to an HTML specification.
* These must be normalized somewhat into a correct form if one
* is to edit them.  Additionally, users don't like to be presented
* with an excessive amount of structure editing, so using traditional
* text editing gestures is preferred over using the HTML structure
* exactly as defined in the HTML document.
* <p>
* The modeling of HTML is provided by the class <code>HTMLDocument</code>.
* Its documention describes the details of how the HTML is modeled.
* The editing support leverages heavily off of the text package.
* <p>
* <dt>
* Extendable/Scalable
* <dd>
* To maximize the usefulness of this kit, a great deal of effort
* has gone into making it extendable.  These are some of the
* features.
* <ol>
*   <li>
*   The parser is replacable.  The default parser is the Hot Java
*   parser which is DTD based.  A different DTD can be used, or an
*   entirely different parser can be used.  To change the parser,
*   reimplement the getParser method.  The default parser is
*   dynamically loaded when first asked for, so the class files
*   will never be loaded if an alternative parser is used.  The
*   default parser is in a separate package called parser below
*   this package.
*   <li>
*   The parser drives the ParserCallback, which is provided by
*   HTMLDocument.  To change the callback, subclass HTMLDocument
*   and reimplement the createDefaultDocument method to return
*   document that produces a different reader.  The reader controls
*   how the document is structured.  Although the Document provides
*   HTML support by default, there is nothing preventing support of
*   non-HTML tags that result in alternative element structures.
*   <li>
*   The default view of the models are provided as a hierarchy of
*   View implementations, so one can easily customize how a particular
*   element is displayed or add capabilities for new kinds of elements
*   by providing new View implementations.  The default set of views
*   are provided by the <code>HTMLFactory</code> class.  This can
*   be easily changed by subclassing or replacing the HTMLFactory
*   and reimplementing the getViewFactory method to return the alternative
*   factory.
*   <li>
*   The View implementations work primarily off of CSS attributes,
*   which are kept in the views.  This makes it possible to have
*   multiple views mapped over the same model that appear substantially
*   different.  This can be especially useful for printing.  For
*   most HTML attributes, the HTML attributes are converted to CSS
*   attributes for display.  This helps make the View implementations
*   more general purpose
* </ol>
* <p>
* <dt>
* Asynchronous Loading
* <dd>
* Larger documents involve a lot of parsing and take some time
* to load.  By default, this kit produces documents that will be
* loaded asynchronously if loaded using <code>JEditorPane.setPage</code>.
* This is controlled by a property on the document.  The method
* <a href="#createDefaultDocument">createDefaultDocument</a> can
* be overriden to change this.  The batching of work is done
* by the <code>HTMLDocument.HTMLReader</code> class.  The actual
* work is done by the <code>DefaultStyledDocument</code> and
* <code>AbstractDocument</code> classes in the text package.
* <p>
* <dt>
* Customization from current LAF
* <dd>
* HTML provides a well known set of features without exactly
* specifying the display characteristics.  Swing has a theme
* mechanism for its look-and-feel implementations.  It is desirable
* for the look-and-feel to feed display characteristics into the
* HTML views.  An user with poor vision for example would want
* high contrast and larger than typical fonts.
* <p>
* The support for this is provided by the <code>StyleSheet</code>
* class.  The presentation of the HTML can be heavily influenced
* by the setting of the StyleSheet property on the EditorKit.
* <p>
* <dt>
* Not lossy
* <dd>
* An EditorKit has the ability to be read and save documents.
* It is generally the most pleasing to users if there is no loss
* of data between the two operation.  The policy of the HTMLEditorKit
* will be to store things not recognized or not necessarily visible
* so they can be subsequently written out.  The model of the HTML document
* should therefore contain all information discovered while reading the
* document.  This is constrained in some ways by the need to support
* editing (i.e. incorrect documents sometimes must be normalized).
* The guiding principle is that information shouldn't be lost, but
* some might be synthesized to produce a more correct model or it might
* be rearranged.
* </dl>
*
* @author  Timothy Prinzing
* @version 1.136 04/07/06
*/
public class HTMLEditorKit extends StyledEditorKit implements Accessible {

    private JEditorPane theEditor;
  
    /**
     * Constructs an HTMLEditorKit, creates a StyleContext,
     * and loads the style sheet.
     */
    public HTMLEditorKit() {

    }

    /**
     * Get the MIME type of the data that this
     * kit represents support for.  This kit supports
     * the type <code>text/html</code>.
     *
     * @return the type
     */
    public String getContentType() {
  return "text/html";
    }

    /**
     * Fetch a factory that is suitable for producing
     * views of any models that are produced by this
     * kit. 
     *
     * @return the factory
     */
    public ViewFactory getViewFactory() {
  return defaultFactory;
    }

    /**
     * Create an uninitialized text storage model
     * that is appropriate for this type of editor.
     *
     * @return the model
     */
    public Document createDefaultDocument() {
  StyleSheet styles = getStyleSheet();
  StyleSheet ss = new StyleSheet();

  ss.addStyleSheet(styles);

  HTMLDocument doc = new HTMLDocument(ss);
  doc.setParser(getParser());
  doc.setAsynchronousLoadPriority(4);
  doc.setTokenThreshold(100);
  return doc;
    }

    /**
     * Inserts content from the given stream. If <code>doc</code> is
     * an instance of HTMLDocument, this will read
     * HTML 3.2 text. Inserting HTML into a non-empty document must be inside
     * the body Element, if you do not insert into the body an exception will
     * be thrown. When inserting into a non-empty document all tags outside
     * of the body (head, title) will be dropped.
     *
     * @param in  the stream to read from
     * @param doc the destination for the insertion
     * @param pos the location in the document to place the
     *   content
     * @exception IOException on any I/O error
     * @exception BadLocationException if pos represents an invalid
     *   location within the document
     * @exception RuntimeException (will eventually be a BadLocationException)
     *            if pos is invalid
     */
    public void read(Reader in, Document doc, int pos) throws IOException, BadLocationException {

  if (doc instanceof HTMLDocument) {
      HTMLDocument hdoc = (HTMLDocument) doc;
      Parser p = getParser();
      if (p == null) {
    throw new IOException("Can't load parser");
      }
      if (pos > doc.getLength()) {
    throw new BadLocationException("Invalid location", pos);
      }

      ParserCallback receiver = hdoc.getReader(pos);
      Boolean ignoreCharset = (Boolean)doc.getProperty("IgnoreCharsetDirective");
      p.parse(in, receiver, (ignoreCharset == null) ? false : ignoreCharset.booleanValue());
      receiver.flush();
  } else {
      super.read(in, doc, pos);
  }
    }

    /**
     * Inserts HTML into an existing document.
     *
     * @param doc       the document to insert into
     * @param offset    the offset to insert HTML at
     * @param popDepth  the number of ElementSpec.EndTagTypes to generate before
     *        inserting
     * @param pushDepth the number of ElementSpec.StartTagTypes with a direction
     *        of ElementSpec.JoinNextDirection that should be generated
     *        before inserting, but after the end tags have been generated
     * @param insertTag the first tag to start inserting into document
     * @exception RuntimeException (will eventually be a BadLocationException)
     *            if pos is invalid
     */
    public void insertHTML(HTMLDocument doc, int offset, String html,
         int popDepth, int pushDepth,
         HTML.Tag insertTag) throws
                 BadLocationException, IOException {
  Parser p = getParser();
  if (p == null) {
      throw new IOException("Can't load parser");
  }
  if (offset > doc.getLength()) {
      throw new BadLocationException("Invalid location", offset);
  }

  ParserCallback receiver = doc.getReader(offset, popDepth, pushDepth,
            insertTag);
  Boolean ignoreCharset = (Boolean)doc.getProperty
                          ("IgnoreCharsetDirective");
  p.parse(new StringReader(html), receiver, (ignoreCharset == null) ?
    false : ignoreCharset.booleanValue());
  receiver.flush();
    }

    /**
     * Write content from a document to the given stream
     * in a format appropriate for this kind of content handler.
     *
     * @param out  the stream to write to
     * @param doc  the source for the write
     * @param pos  the location in the document to fetch the
     *   content
     * @param len  the amount to write out
     * @exception IOException on any I/O error
     * @exception BadLocationException if pos represents an invalid
     *   location within the document
     */
    public void write(Writer out, Document doc, int pos, int len)
  throws IOException, BadLocationException {

  if (doc instanceof HTMLDocument) {
      HTMLWriter w = new HTMLWriter(out, (HTMLDocument)doc, pos, len);
      w.write();
  } else if (doc instanceof StyledDocument) {
      MinimalHTMLWriter w = new MinimalHTMLWriter(out, (StyledDocument)doc, pos, len);
      w.write();
  } else {
      super.write(out, doc, pos, len);
  }
    }

    /**
     * Called when the kit is being installed into the
     * a JEditorPane.
     *
     * @param c the JEditorPane
     */
    public void install(JEditorPane c) {
  c.addMouseListener(linkHandler);
        c.addMouseMotionListener(linkHandler);
  c.addCaretListener(nextLinkAction);
  super.install(c);
        theEditor = c;
    }

    /**
     * Called when the kit is being removed from the
     * JEditorPane.  This is used to unregister any
     * listeners that were attached.
     *
     * @param c the JEditorPane
     */
    public void deinstall(JEditorPane c) {
  c.removeMouseListener(linkHandler);
        c.removeMouseMotionListener(linkHandler);
  c.removeCaretListener(nextLinkAction);
  super.deinstall(c);
        theEditor = null;
    }

    /**
     * Default Cascading Style Sheet file that sets
     * up the tag views.
     */
    public static final String DEFAULT_CSS = "default.css";

    /**
     * Set the set of styles to be used to render the various
     * HTML elements.  These styles are specified in terms of
     * CSS specifications.  Each document produced by the kit
     * will have a copy of the sheet which it can add the
     * document specific styles to.  By default, the StyleSheet
     * specified is shared by all HTMLEditorKit instances.
     * This should be reimplemented to provide a finer granularity
     * if desired.
     */
    public void setStyleSheet(StyleSheet s) {
  defaultStyles = s;
    }

    /**
     * Get the set of styles currently being used to render the
     * HTML elements.  By default the resource specified by
     * DEFAULT_CSS gets loaded, and is shared by all HTMLEditorKit
     * instances.
     */
    public StyleSheet getStyleSheet() {
  if (defaultStyles == null) {
      defaultStyles = new StyleSheet();
      try {
    InputStream is = HTMLEditorKit.getResourceAsStream(DEFAULT_CSS);
    Reader r = new BufferedReader(
            new InputStreamReader(is, "ISO-8859-1"));
    defaultStyles.loadRules(r, null);
    r.close();
      } catch (Throwable e) {
    // on error we simply have no styles... the html
    // will look mighty wrong but still function.
      }
  }
  return defaultStyles;
    }
   
    /**
     * Fetch a resource relative to the HTMLEditorKit classfile.
     * If this is called on 1.2 the loading will occur under the
     * protection of a doPrivileged call to allow the HTMLEditorKit
     * to function when used in an applet.
     *
     * @param name the name of the resource, relative to the
     *  HTMLEditorKit class
     * @return a stream representing the resource
     */
    static InputStream getResourceAsStream(String name) {
  try {
            return ResourceLoader.getResourceAsStream(name);
  } catch (Throwable e) {
      // If the class doesn't exist or we have some other
      // problem we just try to call getResourceAsStream directly.
      return HTMLEditorKit.class.getResourceAsStream(name);
  }
    }

    /**
     * Fetches the command list for the editor.  This is
     * the list of commands supported by the superclass
     * augmented by the collection of commands defined
     * locally for style operations.
     *
     * @return the command list
     */
    public Action[] getActions() {
  return TextAction.augmentList(super.getActions(), this.defaultActions);
    }

    /**
     * Copies the key/values in <code>element</code>s AttributeSet into
     * <code>set</code>. This does not copy component, icon, or element
     * names attributes. Subclasses may wish to refine what is and what
     * isn't copied here. But be sure to first remove all the attributes that
     * are in <code>set</code>.<p>
     * This is called anytime the caret moves over a different location.
     *
     */
    protected void createInputAttributes(Element element,
           MutableAttributeSet set) {
  set.removeAttributes(set);
  set.addAttributes(element.getAttributes());
  set.removeAttribute(StyleConstants.ComposedTextAttribute);

  Object o = set.getAttribute(StyleConstants.NameAttribute);
  if (o instanceof HTML.Tag) {
      HTML.Tag tag = (HTML.Tag)o;
      // PENDING: we need a better way to express what shouldn't be
      // copied when editing...
      if(tag == HTML.Tag.IMG) {
    // Remove the related image attributes, src, width, height
    set.removeAttribute(HTML.Attribute.SRC);
    set.removeAttribute(HTML.Attribute.HEIGHT);
    set.removeAttribute(HTML.Attribute.WIDTH);
    set.addAttribute(StyleConstants.NameAttribute,
         HTML.Tag.CONTENT);
      }
      else if (tag == HTML.Tag.HR || tag == HTML.Tag.BR) {
    // Don't copy HRs or BRs either.
    set.addAttribute(StyleConstants.NameAttribute,
         HTML.Tag.CONTENT);
      }
      else if (tag == HTML.Tag.COMMENT) {
    // Don't copy COMMENTs either
    set.addAttribute(StyleConstants.NameAttribute,
         HTML.Tag.CONTENT);
    set.removeAttribute(HTML.Attribute.COMMENT);
      }
      else if (tag == HTML.Tag.INPUT) {
    // or INPUT either
    set.addAttribute(StyleConstants.NameAttribute,
         HTML.Tag.CONTENT);
    set.removeAttribute(HTML.Tag.INPUT);
      }
      else if (tag instanceof HTML.UnknownTag) {
    // Don't copy unknowns either:(
    set.addAttribute(StyleConstants.NameAttribute,
         HTML.Tag.CONTENT);
    set.removeAttribute(HTML.Attribute.ENDTAG);
      }
  }
    }

    /**
     * Gets the input attributes used for the styled
     * editing actions.
     *
     * @return the attribute set
     */
    public MutableAttributeSet getInputAttributes() {
  if (input == null) {
      input = getStyleSheet().addStyle(null, null);
  }
  return input;
    }

    /**
     * Sets the default cursor.
     *
     * @since 1.3
     */
    public void setDefaultCursor(Cursor cursor) {
  defaultCursor = cursor;
    }

    /**
     * Returns the default cursor.
     *
     * @since 1.3
     */
    public Cursor getDefaultCursor() {
  return defaultCursor;
    }

    /**
     * Sets the cursor to use over links.
     *
     * @since 1.3
     */
    public void setLinkCursor(Cursor cursor) {
  linkCursor = cursor;
    }

    /**
     * Returns the cursor to use over hyper links.
     * @since 1.3
     */
    public Cursor getLinkCursor() {
  return linkCursor;
    }

    /**
     * Indicates whether an html form submission is processed automatically
     * or only <code>FormSubmitEvent</code> is fired.
     *
     * @return true  if html form submission is processed automatically,
     *         false otherwise.
     *
     * @see #setAutoFormSubmission
     * @since 1.5
     */
    public boolean isAutoFormSubmission() {
        return isAutoFormSubmission;
    }

    /**
     * Specifies if an html form submission is processed
     * automatically or only <code>FormSubmitEvent</code> is fired.
     * By default it is set to true.
     *
     * @see #isAutoFormSubmission
     * @see FormSubmitEvent
     * @since 1.5
     */
    public void setAutoFormSubmission(boolean isAuto) {
        isAutoFormSubmission = isAuto;
    }

    /**
     * Creates a copy of the editor kit.
     *
     * @return the copy
     */
    public Object clone() {
  HTMLEditorKit o = (HTMLEditorKit)super.clone();
        if (o != null) {
            o.input = null;
            o.linkHandler = new LinkController();
        }
  return o;
    }

    /**
     * Fetch the parser to use for reading HTML streams.
     * This can be reimplemented to provide a different
     * parser.  The default implementation is loaded dynamically
     * to avoid the overhead of loading the default parser if
     * it's not used.  The default parser is the HotJava parser
     * using an HTML 3.2 DTD.
     */
    protected Parser getParser() {
  if (defaultParser == null) {
      try {
                Class c = Class.forName("javax.swing.text.html.parser.ParserDelegator");
                defaultParser = (Parser) c.newInstance();
      } catch (Throwable e) {
      }
  }
  return defaultParser;
    }

    // ----- Accessibility support -----
    private AccessibleContext accessibleContext;

    /**
     * returns the AccessibleContext associated with this editor kit
     *
     * @return the AccessibleContext associated with this editor kit
     * @since 1.4
     */
    public AccessibleContext getAccessibleContext() {
  if (theEditor == null) {
      return null;
  }
  if (accessibleContext == null) {
      AccessibleHTML a = new AccessibleHTML(theEditor);
      accessibleContext = a.getAccessibleContext();
  }
  return accessibleContext;
    }

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

    private static final Cursor MoveCursor = Cursor.getPredefinedCursor
                              (Cursor.HAND_CURSOR);
    private static final Cursor DefaultCursor = Cursor.getPredefinedCursor
                              (Cursor.DEFAULT_CURSOR);

    /** Shared factory for creating HTML Views. */
    private static final ViewFactory defaultFactory = new HTMLFactory();

    MutableAttributeSet input;
    private static StyleSheet defaultStyles = null;
    private LinkController linkHandler = new LinkController();
    private static Parser defaultParser = null;
    private Cursor defaultCursor = DefaultCursor;
    private Cursor linkCursor = MoveCursor;
    private boolean isAutoFormSubmission = true;

    /**
     * Class to watch the associated component and fire
     * hyperlink events on it when appropriate.
     */
    public static class LinkController extends MouseAdapter implements MouseMotionListener, Serializable {
        private Element curElem = null;
        /**
         * If true, the current element (curElem) represents an image.
         */
        private boolean curElemImage = false;
  private String href = null;
  /** This is used by viewToModel to avoid allocing a new array each
   * time. */
        private transient Position.Bias[] bias = new Position.Bias[1];
        /**
         * Current offset.
         */
        private int curOffset;

  /**
         * Called for a mouse click event.
   * If the component is read-only (ie a browser) then
   * the clicked event is used to drive an attempt to
   * follow the reference specified by a link.
   *
   * @param e the mouse event
   * @see MouseListener#mouseClicked
   */
        public void mouseClicked(MouseEvent e) {
      JEditorPane editor = (JEditorPane) e.getSource();

      if (! editor.isEditable() && SwingUtilities.isLeftMouseButton(e)) {
    Point pt = new Point(e.getX(), e.getY());
    int pos = editor.viewToModel(pt);
    if (pos >= 0) {
        activateLink(pos, editor, e.getX(), e.getY());
    }
      }
  }

        // ignore the drags
        public void mouseDragged(MouseEvent e) {
        }

        // track the moving of the mouse.
        public void mouseMoved(MouseEvent e) {
            JEditorPane editor = (JEditorPane) e.getSource();
      HTMLEditorKit kit = (HTMLEditorKit)editor.getEditorKit();
      boolean adjustCursor = true;
      Cursor newCursor = kit.getDefaultCursor();
            if (!editor.isEditable()) {
                Point pt = new Point(e.getX(), e.getY());
                int pos = editor.getUI().viewToModel(editor, pt, bias);
    if (bias[0] == Position.Bias.Backward && pos > 0) {
        pos--;
    }
                if (pos >= 0 &&(editor.getDocument() instanceof HTMLDocument)){
                    HTMLDocument hdoc = (HTMLDocument)editor.getDocument();
                    Element elem = hdoc.getCharacterElement(pos);
                    if (!doesElementContainLocation(editor, elem, pos,
                                                    e.getX(), e.getY())) {
                        elem = null;
                    }
                    if (curElem != elem || curElemImage) {
                        Element lastElem = curElem;
                        curElem = elem;
                        String href = null;
                        curElemImage = false;
                        if (elem != null) {
                            AttributeSet a = elem.getAttributes();
                            AttributeSet anchor = (AttributeSet)a.
                                                   getAttribute(HTML.Tag.A);
                            if (anchor == null) {
                                curElemImage = (a.getAttribute(StyleConstants.
                                            NameAttribute) == HTML.Tag.IMG);
                                if (curElemImage) {
                                    href = getMapHREF(editor, hdoc, elem, a,
                                                      pos, e.getX(), e.getY());
                                }
                            }
                            else {
                                href = (String)anchor.getAttribute
                                    (HTML.Attribute.HREF);
                            }
                        }

                        if (href != this.href) {
                            // reference changed, fire event(s)
                            fireEvents(editor, hdoc, href, lastElem);
                            this.href = href;
                            if (href != null) {
                                newCursor = kit.getLinkCursor();
                            }
                        }
                        else {
                            adjustCursor = false;
                        }
                    }
                    else {
                        adjustCursor = false;
                    }
                    curOffset = pos;
                }
            }
      if (adjustCursor && editor.getCursor() != newCursor) {
    editor.setCursor(newCursor);
      }
        }

        /**
         * Returns a string anchor if the passed in element has a
         * USEMAP that contains the passed in location.
         */
        private String getMapHREF(JEditorPane html, HTMLDocument hdoc,
                                  Element elem, AttributeSet attr, int offset,
                                  int x, int y) {
            Object useMap = attr.getAttribute(HTML.Attribute.USEMAP);
            if (useMap != null && (useMap instanceof String)) {
                Map m = hdoc.getMap((String)useMap);
                if (m != null && offset < hdoc.getLength()) {
                    Rectangle bounds;
                    TextUI ui = html.getUI();
                    try {
                        Shape lBounds = ui.modelToView(html, offset,
                                                   Position.Bias.Forward);
                        Shape rBounds = ui.modelToView(html, offset + 1,
                                                   Position.Bias.Backward);
                        bounds = lBounds.getBounds();
                        bounds.add((rBounds instanceof Rectangle) ?
                                    (Rectangle)rBounds : rBounds.getBounds());
                    } catch (BadLocationException ble) {
                        bounds = null;
                    }
                    if (bounds != null) {
                        AttributeSet area = m.getArea(x - bounds.x,
                                                      y - bounds.y,
                                                      bounds.width,
                                                      bounds.height);
                        if (area != null) {
                            return (String)area.getAttribute(HTML.Attribute.
                                                             HREF);
                        }
                    }
                }
            }
            return null;
        }

        /**
         * Returns true if the View representing <code>e</code> contains
         * the location <code>x</code>, <code>y</code>. <code>offset</code>
         * gives the offset into the Document to check for.
         */
        private boolean doesElementContainLocation(JEditorPane editor,
                                                   Element e, int offset,
                                                   int x, int y) {
            if (e != null && offset > 0 && e.getStartOffset() == offset) {
                try {
                    TextUI ui = editor.getUI();
                    Shape s1 = ui.modelToView(editor, offset,
                                              Position.Bias.Forward);
        if (s1 == null) {
      return false;
        }
                    Rectangle r1 = (s1 instanceof Rectangle) ? (Rectangle)s1 :
                                    s1.getBounds();
                    Shape s2 = ui.modelToView(editor, e.getEndOffset(),
                                              Position.Bias.Backward);
        if (s2 != null) {
      Rectangle r2 = (s2 instanceof Rectangle) ? (Rectangle)s2 :
                                    s2.getBounds();
      r1.add(r2);
        }
                    return r1.contains(x, y);
                } catch (BadLocationException ble) {
                }
            }
            return true;
        }

  /**
   * Calls linkActivated on the associated JEditorPane
   * if the given position represents a link.<p>This is implemented
   * to forward to the method with the same name, but with the following
   * args both == -1.
         *
         * @param pos the position
         * @param editor the editor pane
   */
  protected void activateLink(int pos, JEditorPane editor) {
      activateLink(pos, editor, -1, -1);
  }

  /**
   * Calls linkActivated on the associated JEditorPane
   * if the given position represents a link. If this was the result
   * of a mouse click, <code>x</code> and
   * <code>y</code> will give the location of the mouse, otherwise
   * they will be < 0.
         *
         * @param pos the position
         * @param html the editor pane
   */
        void activateLink(int pos, JEditorPane html, int x, int y) {
      Document doc = html.getDocument();
      if (doc instanceof HTMLDocument) {
    HTMLDocument hdoc = (HTMLDocument) doc;
    Element e = hdoc.getCharacterElement(pos);
    AttributeSet a = e.getAttributes();
    AttributeSet anchor = (AttributeSet)a.getAttribute(HTML.Tag.A);
    HyperlinkEvent linkEvent = null;
                String description;

                if (anchor == null) {
                    href = getMapHREF(html, hdoc, e, a, pos, x, y);
                }
                else {
                    href = (String)anchor.getAttribute(HTML.Attribute.HREF);
                }

    if (href != null) {
        linkEvent = createHyperlinkEvent(html, hdoc, href, anchor,
                                                     e);
    }
    if (linkEvent != null) {
        html.fireHyperlinkUpdate(linkEvent);
    }
      }
  }

  /**
   * Creates and returns a new instance of HyperlinkEvent. If
   * <code>hdoc</code> is a frame document a HTMLFrameHyperlinkEvent
   * will be created.
   */
  HyperlinkEvent createHyperlinkEvent(JEditorPane html,
              HTMLDocument hdoc, String href,
              AttributeSet anchor,
                                            Element element) {
      URL u;
      try {
    URL base = hdoc.getBase();
    u = new URL(base, href);
    // Following is a workaround for 1.2, in which
    // new URL("file://...", "#...") causes the filename to
    // be lost.
    if (href != null && "file".equals(u.getProtocol()) &&
        href.startsWith("#")) {
        String baseFile = base.getFile();
        String newFile = u.getFile();
        if (baseFile != null && newFile != null &&
      !newFile.startsWith(baseFile)) {
      u = new URL(base, baseFile + href);
        }
    }
      } catch (MalformedURLException m) {
    u = null;
      }
      HyperlinkEvent linkEvent = null;

      if (!hdoc.isFrameDocument()) {
    linkEvent = new HyperlinkEvent(html, HyperlinkEvent.EventType.
                 ACTIVATED, u, href, element);
      } else {
    String target = (anchor != null) ?
        (String)anchor.getAttribute(HTML.Attribute.TARGET) : null;
    if ((target == null) || (target.equals(""))) {
        target = hdoc.getBaseTarget();
    }
    if ((target == null) || (target.equals(""))) {
        target = "_self";
    }
    linkEvent = new HTMLFrameHyperlinkEvent(html, HyperlinkEvent.
           EventType.ACTIVATED, u, href, element, target);
      }
      return linkEvent;
  }

  void fireEvents(JEditorPane editor, HTMLDocument doc, String href,
                        Element lastElem) {
      if (this.href != null) {
    // fire an exited event on the old link
    URL u;
    try {
        u = new URL(doc.getBase(), this.href);
    } catch (MalformedURLException m) {
        u = null;
    }
    HyperlinkEvent exit = new HyperlinkEvent(editor,
               HyperlinkEvent.EventType.EXITED, u, this.href,
                                 lastElem);
    editor.fireHyperlinkUpdate(exit);
      }
      if (href != null) {
    // fire an entered event on the new link
    URL u;
    try {
        u = new URL(doc.getBase(), href);
    } catch (MalformedURLException m) {
        u = null;
    }
    HyperlinkEvent entered = new HyperlinkEvent(editor,
              HyperlinkEvent.EventType.ENTERED,
              u, href, curElem);
    editor.fireHyperlinkUpdate(entered);
      }
  }
    }

    /**
     * Interface to be supported by the parser.  This enables
     * providing a different parser while reusing some of the
     * implementation provided by this editor kit.
     */
    public static abstract class Parser {
  /**
   * Parse the given stream and drive the given callback
   * with the results of the parse.  This method should
   * be implemented to be thread-safe.
   */
  public abstract void parse(Reader r, ParserCallback cb, boolean ignoreCharSet) throws IOException;

    }

    /**
     * The result of parsing drives these callback methods.
     * The open and close actions should be balanced.  The
     * <code>flush</code> method will be the last method
     * called, to give the receiver a chance to flush any
     * pending data into the document.
     * <p>Refer to DocumentParser, the default parser used, for further
     * information on the contents of the AttributeSets, the positions, and
     * other info.
     *
     * @see javax.swing.text.html.parser.DocumentParser
     */
    public static class ParserCallback {
  /**
   * This is passed as an attribute in the attributeset to indicate
   * the element is implied eg, the string '&lt;&gt;foo&lt;\t&gt;'
   * contains an implied html element and an implied body element.
   *
   * @since 1.3
   */
  public static final Object IMPLIED = "_implied_";


        public void flush() throws BadLocationException {
  }

        public void handleText(char[] data, int pos) {
  }

        public void handleComment(char[] data, int pos) {
  }

  public void handleStartTag(HTML.Tag t, MutableAttributeSet a, int pos) {
  }

  public void handleEndTag(HTML.Tag t, int pos) {
  }

  public void handleSimpleTag(HTML.Tag t, MutableAttributeSet a, int pos) {
  }

  public void handleError(String errorMsg, int pos){
  }

  /**
   * This is invoked after the stream has been parsed, but before
   * <code>flush</code>. <code>eol</code> will be one of \n, \r
   * or \r\n, which ever is encountered the most in parsing the
   * stream.
   *
   * @since 1.3
   */
  public void handleEndOfLineString(String eol) {
  }
    }

    /**
     * A factory to build views for HTML.  The following
     * table describes what this factory will build by
     * default.
     *
     * <table summary="Describes the tag and view created by this factory by default">
     * <tr>
     * <th align=left>Tag<th align=left>View created
     * </tr><tr>
     * <td>HTML.Tag.CONTENT<td>InlineView
     * </tr><tr>
     * <td>HTML.Tag.IMPLIED<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.P<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H1<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H2<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H3<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H4<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H5<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.H6<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.DT<td>javax.swing.text.html.ParagraphView
     * </tr><tr>
     * <td>HTML.Tag.MENU<td>ListView
     * </tr><tr>
     * <td>HTML.Tag.DIR<td>ListView
     * </tr><tr>
     * <td>HTML.Tag.UL<td>ListView
     * </tr><tr>
     * <td>HTML.Tag.OL<td>ListView
     * </tr><tr>
     * <td>HTML.Tag.LI<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.DL<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.DD<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.BODY<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.HTML<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.CENTER<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.DIV<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.BLOCKQUOTE<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.PRE<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.BLOCKQUOTE<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.PRE<td>BlockView
     * </tr><tr>
     * <td>HTML.Tag.IMG<td>ImageView
     * </tr><tr>
     * <td>HTML.Tag.HR<td>HRuleView
     * </tr><tr>
     * <td>HTML.Tag.BR<td>BRView
     * </tr><tr>
     * <td>HTML.Tag.TABLE<td>javax.swing.text.html.TableView
     * </tr><tr>
     * <td>HTML.Tag.INPUT<td>FormView
     * </tr><tr>
     * <td>HTML.Tag.SELECT<td>FormView
     * </tr><tr>
     * <td>HTML.Tag.TEXTAREA<td>FormView
     * </tr><tr>
     * <td>HTML.Tag.OBJECT<td>ObjectView
     * </tr><tr>
     * <td>HTML.Tag.FRAMESET<td>FrameSetView
     * </tr><tr>
     * <td>HTML.Tag.FRAME<td>FrameView
     * </tr>
     * </table>
     */
    public static class HTMLFactory implements ViewFactory {
   
  /**
   * Creates a view from an element.
   *
   * @param elem the element
   * @return the view
   */
        public View create(Element elem) {
            AttributeSet attrs = elem.getAttributes();
       Object elementName =
                attrs.getAttribute(AbstractDocument.ElementNameAttribute);
      Object o = (elementName != null) ?
    null : attrs.getAttribute(StyleConstants.NameAttribute);
      if (o instanceof HTML.Tag) {
    HTML.Tag kind = (HTML.Tag) o;
    if (kind == HTML.Tag.CONTENT) {
        return new InlineView(elem);
    } else if (kind == HTML.Tag.IMPLIED) {
        String ws = (String) elem.getAttributes().getAttribute(
      CSS.Attribute.WHITE_SPACE);
        if ((ws != null) && ws.equals("pre")) {
      return new LineView(elem);
        }
        return new javax.swing.text.html.ParagraphView(elem);
    } else if ((kind == HTML.Tag.P) ||
         (kind == HTML.Tag.H1) ||
         (kind == HTML.Tag.H2) ||
         (kind == HTML.Tag.H3) ||
         (kind == HTML.Tag.H4) ||
         (kind == HTML.Tag.H5) ||
         (kind == HTML.Tag.H6) ||
         (kind == HTML.Tag.DT)) {
        // paragraph
        return new javax.swing.text.html.ParagraphView(elem);
    } else if ((kind == HTML.Tag.MENU) ||
         (kind == HTML.Tag.DIR) ||
         (kind == HTML.Tag.UL)   ||
         (kind == HTML.Tag.OL)) {
        return new ListView(elem);
    } else if (kind == HTML.Tag.BODY) {
        return new BodyBlockView(elem);
    } else if (kind == HTML.Tag.HTML) {
        return new BlockView(elem, View.Y_AXIS);
    } else if ((kind == HTML.Tag.LI) ||
         (kind == HTML.Tag.CENTER) ||
         (kind == HTML.Tag.DL) ||
         (kind == HTML.Tag.DD) ||
         (kind == HTML.Tag.DIV) ||
         (kind == HTML.Tag.BLOCKQUOTE) ||
         (kind == HTML.Tag.PRE) ||
                           (kind == HTML.Tag.FORM)) {
        // vertical box
        return new BlockView(elem, View.Y_AXIS);
    } else if (kind == HTML.Tag.NOFRAMES) {
        return new NoFramesView(elem, View.Y_AXIS);
    } else if (kind==HTML.Tag.IMG) {
        return new ImageView(elem);
    } else if (kind == HTML.Tag.ISINDEX) {
        return new IsindexView(elem);
    } else if (kind == HTML.Tag.HR) {
        return new HRuleView(elem);
    } else if (kind == HTML.Tag.BR) {
        return new BRView(elem);
    } else if (kind == HTML.Tag.TABLE) {
        return new javax.swing.text.html.TableView(elem);
    } else if ((kind == HTML.Tag.INPUT) ||
         (kind == HTML.Tag.SELECT) ||
         (kind == HTML.Tag.TEXTAREA)) {
        return new FormView(elem);
    } else if (kind == HTML.Tag.OBJECT) {
        return new ObjectView(elem);
    } else if (kind == HTML.Tag.FRAMESET) {
                     if (elem.getAttributes().isDefined(HTML.Attribute.ROWS)) {
                         return new FrameSetView(elem, View.Y_AXIS);
                     } else if (elem.getAttributes().isDefined(HTML.Attribute.COLS)) {
                         return new FrameSetView(elem, View.X_AXIS);
                     }
                     throw new RuntimeException("Can't build a"  + kind + ", " + elem + ":" +
                                     "no ROWS or COLS defined.");
                } else if (kind == HTML.Tag.FRAME) {
         return new FrameView(elem);
                } else if (kind instanceof HTML.UnknownTag) {
        return new HiddenTagView(elem);
    } else if (kind == HTML.Tag.COMMENT) {
        return new CommentView(elem);
    } else if (kind == HTML.Tag.HEAD) {
        // Make the head never visible, and never load its
        // children. For Cursor positioning,
        // getNextVisualPositionFrom is overriden to always return
        // the end offset of the element.
        return new BlockView(elem, View.X_AXIS) {
      public float getPreferredSpan(int axis) {
          return 0;
      }
      public float getMinimumSpan(int axis) {
          return 0;
      }
      public float getMaximumSpan(int axis) {
          return 0;
      }
      protected void loadChildren(ViewFactory f) {
      }
                        public Shape modelToView(int pos, Shape a,
                               Position.Bias b) throws BadLocationException {
                            return a;
                        }
      public int getNextVisualPositionFrom(int pos,
             Position.Bias b, Shape a,
             int direction, Position.Bias[] biasRet) {
          return getElement().getEndOffset();
      }
        };
    } else if ((kind == HTML.Tag.TITLE) ||
         (kind == HTML.Tag.META) ||
         (kind == HTML.Tag.LINK) ||
         (kind == HTML.Tag.STYLE) ||
         (kind == HTML.Tag.SCRIPT) ||
         (kind == HTML.Tag.AREA) ||
         (kind == HTML.Tag.MAP) ||
         (kind == HTML.Tag.PARAM) ||
         (kind == HTML.Tag.APPLET)) {
        return new HiddenTagView(elem);
    }
      }
      // If we get here, it's either an element we don't know about
      // or something from StyledDocument that doesn't have a mapping to HTML.
      String nm = (elementName != null) ? (String)elementName :
                                                elem.getName();
      if (nm != null) {
    if (nm.equals(AbstractDocument.ContentElementName)) {
        return new LabelView(elem);
    } else if (nm.equals(AbstractDocument.ParagraphElementName)) {
        return new ParagraphView(elem);
    } else if (nm.equals(AbstractDocument.SectionElementName)) {
        return new BoxView(elem, View.Y_AXIS);
    } else if (nm.equals(StyleConstants.ComponentElementName)) {
        return new ComponentView(elem);
    } else if (nm.equals(StyleConstants.IconElementName)) {
        return new IconView(elem);
    }
      }
 
      // default to text display
      return new LabelView(elem);
  }

  static class BodyBlockView extends BlockView implements ComponentListener {
      public BodyBlockView(Element elem) {
    super(elem,View.Y_AXIS);
      }
      // reimplement major axis requirements to indicate that the
      // block is flexible for the body element... so that it can
      // be stretched to fill the background properly.
      protected SizeRequirements calculateMajorAxisRequirements(int axis, SizeRequirements r) {
    r = super.calculateMajorAxisRequirements(axis, r);
    r.maximum = Integer.MAX_VALUE;
    return r;
      }

      protected void layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans) {
    Container container = getContainer();
    Container parentContainer;
    if (container != null
        && (container instanceof javax.swing.JEditorPane)
        && (parentContainer = container.getParent()) != null
        && (parentContainer instanceof javax.swing.JViewport)) {
        JViewport viewPort = (JViewport)parentContainer;
        Object cachedObject;
        if (cachedViewPort != null) {
      if ((cachedObject = cachedViewPort.get()) != null) {
          if (cachedObject != viewPort) {
        ((JComponent)cachedObject).removeComponentListener(this);
          }
      } else {
          cachedViewPort = null;
      }
        }
        if (cachedViewPort == null) {
      viewPort.addComponentListener(this);
      cachedViewPort = new WeakReference(viewPort);
        }

        componentVisibleWidth = viewPort.getExtentSize().width;
                    if (componentVisibleWidth > 0) {
        Insets insets = container.getInsets();
        viewVisibleWidth = componentVisibleWidth - insets.left - getLeftInset();
        //try to use viewVisibleWidth if it is smaller than targetSpan
        targetSpan = Math.min(targetSpan, viewVisibleWidth);
        }
    } else {
        if (cachedViewPort != null) {
      Object cachedObject;
      if ((cachedObject = cachedViewPort.get()) != null) {
          ((JComponent)cachedObject).removeComponentListener(this);
      }
      cachedViewPort = null;
        }
    }
                super.layoutMinorAxis(targetSpan, axis, offsets, spans);
      }

      public void setParent(View parent) {
    //if parent == null unregister component listener
    if (parent == null) {
        if (cachedViewPort != null) {
      Object cachedObject;
      if ((cachedObject = cachedViewPort.get()) != null) {
          ((JComponent)cachedObject).removeComponentListener(this);
      }
      cachedViewPort = null;
        }
    }
    super.setParent(parent);
      }

      public void componentResized(ComponentEvent e) {
    if ( !(e.getSource() instanceof JViewport) ) {
        return;
    }
    JViewport viewPort = (JViewport)e.getSource();
    if (componentVisibleWidth != viewPort.getExtentSize().width) {
        Document doc = getDocument();
        if (doc instanceof AbstractDocument) {
      AbstractDocument document = (AbstractDocument)getDocument();
      document.readLock();
      try {
          layoutChanged(X_AXIS);
          preferenceChanged(null, true, true);
      } finally {
          document.readUnlock();
      }
     
        }
    }
      }
      public void componentHidden(ComponentEvent e) {
      }
      public void componentMoved(ComponentEvent e) {
      }
      public void componentShown(ComponentEvent e) {
      }
      /*
             * we keep weak reference to viewPort if and only if BodyBoxView is listening for ComponentEvents
       * only in that case cachedViewPort is not equal to null.
       * we need to keep this reference in order to remove BodyBoxView from viewPort listeners.
       *
       */
      private Reference cachedViewPort = null;
      private boolean isListening = false;
      private int viewVisibleWidth = Integer.MAX_VALUE;
      private int componentVisibleWidth = Integer.MAX_VALUE;
  }
 
    }
   
    // --- Action implementations ------------------------------

/** The bold action identifier
*/
    public static final String  BOLD_ACTION = "html-bold-action";
/** The italic action identifier
*/
    public static final String  ITALIC_ACTION = "html-italic-action";
/** The paragraph left indent action identifier
*/
    public static final String  PARA_INDENT_LEFT = "html-para-indent-left";
/** The paragraph right indent action identifier
*/
    public static final String  PARA_INDENT_RIGHT = "html-para-indent-right";
/** The  font size increase to next value action identifier
*/
    public static final String  FONT_CHANGE_BIGGER = "html-font-bigger";
/** The font size decrease to next value action identifier
*/
    public static final String  FONT_CHANGE_SMALLER = "html-font-smaller";
/** The Color choice action identifier
     The color is passed as an argument
*/
    public static final String  COLOR_ACTION = "html-color-action";
/** The logical style choice action identifier
     The logical style is passed in as an argument
*/
    public static final String  LOGICAL_STYLE_ACTION = "html-logical-style-action";
    /**
     * Align images at the top.
     */
    public static final String  IMG_ALIGN_TOP = "html-image-align-top";

    /**
     * Align images in the middle.
     */
    public static final String  IMG_ALIGN_MIDDLE = "html-image-align-middle";

    /**
     * Align images at the bottom.
     */
    public static final String  IMG_ALIGN_BOTTOM = "html-image-align-bottom";

    /**
     * Align images at the border.
     */
    public static final String  IMG_BORDER = "html-image-border";


    /** HTML used when inserting tables. */
    private static final String INSERT_TABLE_HTML = "<table border=1><tr><td></td></tr></table>";

    /** HTML used when inserting unordered lists. */
    private static final String INSERT_UL_HTML = "<ul><li></li></ul>";

    /** HTML used when inserting ordered lists. */
    private static final String INSERT_OL_HTML = "<ol><li></li></ol>";

    /** HTML used when inserting hr. */
    private static final String INSERT_HR_HTML = "<hr>";

    /** HTML used when inserting pre. */
    private static final String INSERT_PRE_HTML = "<pre></pre>";

    private static NavigateLinkAction nextLinkAction =
  new NavigateLinkAction("next-link-action");

    private static NavigateLinkAction previousLinkAction =
  new NavigateLinkAction("previous-link-action");

    private static ActivateLinkAction activateLinkAction =
  new ActivateLinkAction("activate-link-action");
 
    private static final Action[] defaultActions = {
  new InsertHTMLTextAction("InsertTable", INSERT_TABLE_HTML,
         HTML.Tag.BODY, HTML.Tag.TABLE),
  new InsertHTMLTextAction("InsertTableRow", INSERT_TABLE_HTML,
         HTML.Tag.TABLE, HTML.Tag.TR,
         HTML.Tag.BODY, HTML.Tag.TABLE),
  new InsertHTMLTextAction("InsertTableDataCell", INSERT_TABLE_HTML,
         HTML.Tag.TR, HTML.Tag.TD,
         HTML.Tag.BODY, HTML.Tag.TABLE),
  new InsertHTMLTextAction("InsertUnorderedList", INSERT_UL_HTML,
         HTML.Tag.BODY, HTML.Tag.UL),
  new InsertHTMLTextAction("InsertUnorderedListItem", INSERT_UL_HTML,
         HTML.Tag.UL, HTML.Tag.LI,
         HTML.Tag.BODY, HTML.Tag.UL),
  new InsertHTMLTextAction("InsertOrderedList", INSERT_OL_HTML,
         HTML.Tag.BODY, HTML.Tag.OL),
  new InsertHTMLTextAction("InsertOrderedListItem", INSERT_OL_HTML,
         HTML.Tag.OL, HTML.Tag.LI,
         HTML.Tag.BODY, HTML.Tag.OL),
  new InsertHRAction(),
  new InsertHTMLTextAction("InsertPre", INSERT_PRE_HTML,
         HTML.Tag.BODY, HTML.Tag.PRE),
  nextLinkAction, previousLinkAction, activateLinkAction,
   
        new BeginAction(beginAction, false),
        new BeginAction(selectionBeginAction, true)
    };


    /**
     * An abstract Action providing some convenience methods that may
     * be useful in inserting HTML into an existing document.
     * <p>NOTE: None of the convenience methods obtain a lock on the
     * document. If you have another thread modifying the text these
     * methods may have inconsistent behavior, or return the wrong thing.
     */
    public static abstract class HTMLTextAction extends StyledTextAction {
  public HTMLTextAction(String name) {
      super(name);
  }

  /**
   * @return HTMLDocument of <code>e</code>.
   */
  protected HTMLDocument getHTMLDocument(JEditorPane e) {
      Document d = e.getDocument();
      if (d instanceof HTMLDocument) {
    return (HTMLDocument) d;
      }
      throw new IllegalArgumentException("document must be HTMLDocument");
  }

  /**
   * @return HTMLEditorKit for <code>e</code>.
   */
        protected HTMLEditorKit getHTMLEditorKit(JEditorPane e) {
      EditorKit k = e.getEditorKit();
      if (k instanceof HTMLEditorKit) {
    return (HTMLEditorKit) k;
      }
      throw new IllegalArgumentException("EditorKit must be HTMLEditorKit");
  }

  /**
   * Returns an array of the Elements that contain <code>offset</code>.
   * The first elements corresponds to the root.
   */
  protected Element[] getElementsAt(HTMLDocument doc, int offset) {
      return getElementsAt(doc.getDefaultRootElement(), offset, 0);
  }

  /**
   * Recursive method used by getElementsAt.
   */
  private Element[] getElementsAt(Element parent, int offset,
          int depth) {
      if (parent.isLeaf()) {
    Element[] retValue = new Element[depth + 1];
    retValue[depth] = parent;
    return retValue;
      }
      Element[] retValue = getElementsAt(parent.getElement
        (parent.getElementIndex(offset)), offset, depth + 1);
      retValue[depth] = parent;
      return retValue;
  }

  /**
   * Returns number of elements, starting at the deepest leaf, needed
   * to get to an element representing <code>tag</code>. This will
   * return -1 if no elements is found representing <code>tag</code>,
   * or 0 if the parent of the leaf at <code>offset</code> represents
   * <code>tag</code>.
   */
  protected int elementCountToTag(HTMLDocument doc, int offset,
          HTML.Tag tag) {
      int depth = -1;
      Element e = doc.getCharacterElement(offset);
      while (e != null && e.getAttributes().getAttribute
       (StyleConstants.NameAttribute) != tag) {
    e = e.getParentElement();
    depth++;
      }
      if (e == null) {
    return -1;
      }
      return depth;
  }

  /**
   * Returns the deepest element at <code>offset</code> matching
   * <code>tag</code>.
   */
  protected Element findElementMatchingTag(HTMLDocument doc, int offset,
             HTML.Tag tag) {
      Element e = doc.getDefaultRootElement();
      Element lastMatch = null;
      while (e != null) {
    if (e.getAttributes().getAttribute
       (StyleConstants.NameAttribute) == tag) {
        lastMatch = e;
    }
    e = e.getElement(e.getElementIndex(offset));
      }
      return lastMatch;
  }
    }


    /**
     * InsertHTMLTextAction can be used to insert an arbitrary string of HTML
     * into an existing HTML document. At least two HTML.Tags need to be
     * supplied. The first Tag, parentTag, identifies the parent in
     * the document to add the elements to. The second tag, addTag,
     * identifies the first tag that should be added to the document as
     * seen in the HTML string. One important thing to remember, is that
     * the parser is going to generate all the appropriate tags, even if
     * they aren't in the HTML string passed in.<p>
     * For example, lets say you wanted to create an action to insert
     * a table into the body. The parentTag would be HTML.Tag.BODY,
     * addTag would be HTML.Tag.TABLE, and the string could be something
     * like &lt;table&gt;&lt;tr&gt;&lt;td&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;.
     * <p>There is also an option to supply an alternate parentTag and
     * addTag. These will be checked for if there is no parentTag at
     * offset.
     */
    public static class InsertHTMLTextAction extends HTMLTextAction {
  public InsertHTMLTextAction(String name, String html,
            HTML.Tag parentTag, HTML.Tag addTag) {
      this(name, html, parentTag, addTag, null, null);
  }

  public InsertHTMLTextAction(String name, String html,
            HTML.Tag parentTag,
            HTML.Tag addTag,
            HTML.Tag alternateParentTag,
            HTML.Tag alternateAddTag) {
      this(name, html, parentTag, addTag, alternateParentTag,
     alternateAddTag, true);
  }

  /* public */
  InsertHTMLTextAction(String name, String html,
            HTML.Tag parentTag,
            HTML.Tag addTag,
            HTML.Tag alternateParentTag,
            HTML.Tag alternateAddTag,
            boolean adjustSelection) {
      super(name);
      this.html = html;
      this.parentTag = parentTag;
      this.addTag = addTag;
      this.alternateParentTag = alternateParentTag;
      this.alternateAddTag = alternateAddTag;
      this.adjustSelection = adjustSelection;
  }

  /**
   * A cover for HTMLEditorKit.insertHTML. If an exception it
   * thrown it is wrapped in a RuntimeException and thrown.
   */
  protected void insertHTML(JEditorPane editor, HTMLDocument doc,
          int offset, String html, int popDepth,
          int pushDepth, HTML.Tag addTag) {
      try {
    getHTMLEditorKit(editor).insertHTML(doc, offset, html,
                popDepth, pushDepth,
                addTag);
      } catch (IOException ioe) {
    throw new RuntimeException("Unable to insert: " + ioe);
      } catch (BadLocationException ble) {
    throw new RuntimeException("Unable to insert: " + ble);
      }
  }

  /**
   * This is invoked when inserting at a boundary. It determines
   * the number of pops, and then the number of pushes that need
   * to be performed, and then invokes insertHTML.
   * @since 1.3
   */
  protected void insertAtBoundary(JEditorPane editor, HTMLDocument doc,
          int offset, Element insertElement,
          String html, HTML.Tag parentTag,
          HTML.Tag addTag) {
      insertAtBoundry(editor, doc, offset, insertElement, html,
          parentTag, addTag);
  }

  /**
   * This is invoked when inserting at a boundary. It determines
   * the number of pops, and then the number of pushes that need
   * to be performed, and then invokes insertHTML.
   * @deprecated As of Java 2 platform v1.3, use insertAtBoundary
   */
        @Deprecated
  protected void insertAtBoundry(JEditorPane editor, HTMLDocument doc,
               int offset, Element insertElement,
               String html, HTML.Tag parentTag,
               HTML.Tag addTag) {
      // Find the common parent.
      Element e;
      Element commonParent;
      boolean isFirst = (offset == 0);

      if (offset > 0 || insertElement == null) {
    e = doc.getDefaultRootElement();
    while (e != null && e.getStartOffset() != offset &&
           !e.isLeaf()) {
        e = e.getElement(e.getElementIndex(offset));
    }
    commonParent = (e != null) ? e.getParentElement() : null;
      }
      else {
    // If inserting at the origin, the common parent is the
    // insertElement.
    commonParent = insertElement;
      }
      if (commonParent != null) {
    // Determine how many pops to do.
    int pops = 0;
    int pushes = 0;
    if (isFirst && insertElement != null) {
        e = commonParent;
        while (e != null && !e.isLeaf()) {
      e = e.getElement(e.getElementIndex(offset));
      pops++;
        }
    }
    else {
        e = commonParent;
        offset--;
        while (e != null && !e.isLeaf()) {
      e = e.getElement(e.getElementIndex(offset));
      pops++;
        }

        // And how many pushes
        e = commonParent;
        offset++;
        while (e != null && e != insertElement) {
      e = e.getElement(e.getElementIndex(offset));
      pushes++;
        }
    }
    pops = Math.max(0, pops - 1);

    // And insert!
    insertHTML(editor, doc, offset, html, pops, pushes, addTag);
      }
  }

  /**
   * If there is an Element with name <code>tag</code> at
   * <code>offset</code>, this will invoke either insertAtBoundary
   * or <code>insertHTML</code>. This returns true if there is
   * a match, and one of the inserts is invoked.
   */
  /*protected*/
  boolean insertIntoTag(JEditorPane editor, HTMLDocument doc,
            int offset, HTML.Tag tag, HTML.Tag addTag) {
      Element e = findElementMatchingTag(doc, offset, tag);
      if (e != null && e.getStartOffset() == offset) {
    insertAtBoundary(editor, doc, offset, e, html,
         tag, addTag);
    return true;
      }
      else if (offset > 0) {
    int depth = elementCountToTag(doc, offset - 1, tag);
    if (depth != -1) {
        insertHTML(editor, doc, offset, html, depth, 0, addTag);
        return true;
    }
      }
      return false;
  }

  /**
   * Called after an insertion to adjust the selection.
   */
  /* protected */
  void adjustSelection(JEditorPane pane, HTMLDocument doc,
           int startOffset, int oldLength) {
      int newLength = doc.getLength();
      if (newLength != oldLength && startOffset < newLength) {
    if (startOffset > 0) {
        String text;
        try {
      text = doc.getText(startOffset - 1, 1);
        } catch (BadLocationException ble) {
      text = null;
        }
        if (text != null && text.length() > 0 &&
      text.charAt(0) == '\n') {
      pane.select(startOffset, startOffset);
        }
        else {
      pane.select(startOffset + 1, startOffset + 1);
        }
    }
    else {
        pane.select(1, 1);
    }
      }
  }

        /**
         * Inserts the HTML into the document.
         *
         * @param ae the event
         */
        public void actionPerformed(ActionEvent ae) {
      JEditorPane editor = getEditor(ae);
      if (editor != null) {
    HTMLDocument doc = getHTMLDocument(editor);
    int offset = editor.getSelectionStart();
    int length = doc.getLength();
    boolean inserted;
    // Try first choice
    if (!insertIntoTag(editor, doc, offset, parentTag, addTag) &&
        alternateParentTag != null) {
        // Then alternate.
        inserted = insertIntoTag(editor, doc, offset,
               alternateParentTag,
               alternateAddTag);
    }
    else {
        inserted = true;
    }
    if (adjustSelection && inserted) {
        adjustSelection(editor, doc, offset, length);
    }
      }
  }

  /** HTML to insert. */
  protected String html;
  /** Tag to check for in the document. */
  protected HTML.Tag parentTag;
  /** Tag in HTML to start adding tags from. */
  protected HTML.Tag addTag;
  /** Alternate Tag to check for in the document if parentTag is
   * not found. */
  protected HTML.Tag alternateParentTag;
  /** Alternate tag in HTML to start adding tags from if parentTag
   * is not found and alternateParentTag is found. */
  protected HTML.Tag alternateAddTag;
  /** True indicates the selection should be adjusted after an insert. */
  boolean adjustSelection;
    }


    /**
     * InsertHRAction is special, at actionPerformed time it will determine
     * the parent HTML.Tag based on the paragraph element at the selection
     * start.
     */
    static class InsertHRAction extends InsertHTMLTextAction {
  InsertHRAction() {
      super("InsertHR", "<hr>", null, HTML.Tag.IMPLIED, null, null,
      false);
  }

        /**
         * Inserts the HTML into the document.
         *
         * @param ae the event
         */
        public void actionPerformed(ActionEvent ae) {
      JEditorPane editor = getEditor(ae);
      if (editor != null) {
    HTMLDocument doc = getHTMLDocument(editor);
    int offset = editor.getSelectionStart();
    Element paragraph = doc.getParagraphElement(offset);
    if (paragraph.getParentElement() != null) {
        parentTag = (HTML.Tag)paragraph.getParentElement().
                      getAttributes().getAttribute
                      (StyleConstants.NameAttribute);
        super.actionPerformed(ae);
    }
      }
  }
 
    }

    /*
     * Returns the object in an AttributeSet matching a key
     */
    static private Object getAttrValue(AttributeSet attr, HTML.Attribute key) {
  Enumeration names = attr.getAttributeNames();
  while (names.hasMoreElements()) {
      Object nextKey = names.nextElement();
      Object nextVal = attr.getAttribute(nextKey);
      if (nextVal instanceof AttributeSet) {
    Object value = getAttrValue((AttributeSet)nextVal, key);
    if (value != null) {
        return value;
    }
      } else if (nextKey == key) {
    return nextVal;
     
  }
  return null;
    }

    /*
     * Action to move the focus on the next or previous hypertext link
     * or object. TODO: This method relies on support from the
     * javax.accessibility package.  The text package should support
     * keyboard navigation of text elements directly.
     */
    static class NavigateLinkAction extends TextAction
        implements CaretListener {

  private static int prevHypertextOffset = -1;
  private static boolean foundLink = false;
        private static FocusHighlightPainter focusPainter =
      new FocusHighlightPainter(null);
  private Object selectionTag;
  private boolean focusBack = false;

        /*
         * Create this action with the appropriate identifier.
         */
        public NavigateLinkAction(String actionName) {
            super(actionName);
      if ("previous-link-action".equals(actionName)) {
    focusBack = true;
      }
        }
 
  /**
   * Called when the caret position is updated.
   *
   * @param e the caret event
   */
  public void caretUpdate(CaretEvent e) {
      if (foundLink) {
    foundLink = false;
    // TODO: The AccessibleContext for the editor should register
    // as a listener for CaretEvents and forward the events to
    // assistive technologies listening for such events.
    Object src = e.getSource();
    if (src instanceof JTextComponent) {
        ((JTextComponent)src).getAccessibleContext().firePropertyChange(
                        AccessibleContext.ACCESSIBLE_HYPERTEXT_OFFSET,
            new Integer(prevHypertextOffset),
            new Integer(e.getDot()));
    }
      }
  }

        /*
   * The operation to perform when this action is triggered.
   */
        public void actionPerformed(ActionEvent e) {
            JTextComponent comp = getTextComponent(e);
      if (comp == null || comp.isEditable()) {
    return;
      }
      Document doc = comp.getDocument();
      if (doc == null) {
    return;
      }
      // TODO: Should start successive iterations from the
      // current caret position.
      ElementIterator ei = new ElementIterator(doc);

      int currentOffset = comp.getCaretPosition();
      int prevStartOffset = -1;
      int prevEndOffset = -1;
   
      // highlight the next link or object after the current caret position
      Element nextElement = null;
      while ((nextElement = ei.next()) != null) {
    String name = nextElement.getName();
    AttributeSet attr = nextElement.getAttributes();
   
    Object href = getAttrValue(attr, HTML.Attribute.HREF);
    if (!(name.equals(HTML.Tag.OBJECT.toString())) && href == null) {
        continue;
    }
   
    int elementOffset = nextElement.getStartOffset();
    if (focusBack) {
        if (elementOffset >= currentOffset &&
      prevStartOffset >= 0) {

      foundLink = true;
      comp.setCaretPosition(prevStartOffset);
      moveCaretPosition(comp, prevStartOffset,
            prevEndOffset);
      prevHypertextOffset = prevStartOffset;
      return;
        }
    } else { // focus forward
        if (elementOffset > currentOffset) {

      foundLink = true;
      comp.setCaretPosition(elementOffset);
      moveCaretPosition(comp, elementOffset,
            nextElement.getEndOffset());
      prevHypertextOffset = elementOffset;
      return;
        }
    }
    prevStartOffset = nextElement.getStartOffset();
    prevEndOffset = nextElement.getEndOffset();
      }
            if (focusBack && prevStartOffset >= 0) {
                foundLink = true;
                comp.setCaretPosition(prevStartOffset);
                moveCaretPosition(comp, prevStartOffset,
                                  prevEndOffset);
                prevHypertextOffset = prevStartOffset;
                return;
            }
        }
 
  /*
   * Moves the caret from mark to dot
   */
  private void moveCaretPosition(JTextComponent comp, int mark, int dot) {
      Highlighter h = comp.getHighlighter();
      if (h != null) {
    int p0 = Math.min(dot, mark);
    int p1 = Math.max(dot, mark);
    try {
        if (selectionTag != null) {
      h.changeHighlight(selectionTag, p0, p1);
        } else {
      Highlighter.HighlightPainter p = focusPainter;
      selectionTag = h.addHighlight(p0, p1, p);
        }
    } catch (BadLocationException e) {
    }
      }
  }

  /**
   * A highlight painter that draws a one-pixel border around
   * the highlighted area.
   */
        static class FocusHighlightPainter extends
      DefaultHighlighter.DefaultHighlightPainter {

      FocusHighlightPainter(Color color) {
    super(color);
      }
     
      /**
       * Paints a portion of a highlight.
       *
       * @param g the graphics context
       * @param offs0 the starting model offset >= 0
       * @param offs1 the ending model offset >= offs1
       * @param bounds the bounding box of the view, which is not
       *        necessarily the region to paint.
       * @param c the editor
       * @param view View painting for
       * @return region in which drawing occurred
       */
      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.drawRect(alloc.x, alloc.y, alloc.width - 1, alloc.height);
        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.drawRect(r.x, r.y, r.width - 1, r.height);
      return r;
        } catch (BadLocationException e) {
      // can't render
        }
    }
    // Only if exception
    return null;
      }
  }
    }

    /*
     * Action to activate the hypertext link that has focus.
     * TODO: This method relies on support from the
     * javax.accessibility package.  The text package should support
     * keyboard navigation of text elements directly.
     */
    static class ActivateLinkAction extends TextAction {

        /**
         * Create this action with the appropriate identifier.
         */
        public ActivateLinkAction(String actionName) {
            super(actionName);
        }

  /*
   * activates the hyperlink at offset
   */
  private void activateLink(String href, HTMLDocument doc,
          JEditorPane editor, int offset) {
      try {
    URL page =
        (URL)doc.getProperty(Document.StreamDescriptionProperty);
    URL url = new URL(page, href);
    HyperlinkEvent linkEvent = new HyperlinkEvent
        (editor, HyperlinkEvent.EventType.
         ACTIVATED, url, url.toExternalForm(),
         doc.getCharacterElement(offset));
    editor.fireHyperlinkUpdate(linkEvent);
      } catch (MalformedURLException m) {
      }     
  }

  /*
   * Invokes default action on the object in an element
   */
  private void doObjectAction(JEditorPane editor, Element elem) {
      View view = getView(editor, elem);
      if (view != null && view instanceof ObjectView) {
    Component comp = ((ObjectView)view).getComponent();
    if (comp != null && comp instanceof Accessible) {
        AccessibleContext ac = ((Accessible)comp).getAccessibleContext();
        if (ac != null) {
      AccessibleAction aa = ac.getAccessibleAction();
      if (aa != null) {
          aa.doAccessibleAction(0);
      }
        }
    }
      }
  }
 
  /*
   * Returns the root view for a document
   */
  private View getRootView(JEditorPane editor) {
      return editor.getUI().getRootView(editor);
  }

        /*
   * Returns a view associated with an element
         */
        private View getView(JEditorPane editor, Element elem) {
            Object lock = lock(editor);
            try {
                View rootView = getRootView(editor);
                int start = elem.getStartOffset();
                if (rootView != null) {
                    return getView(rootView, elem, start);
                }
                return null;
            } finally {
                unlock(lock);
            }
        }

  private View getView(View parent, Element elem, int start) {
            if (parent.getElement() == elem) {
                return parent;
            }
            int index = parent.getViewIndex(start, Position.Bias.Forward);
     
            if (index != -1 && index < parent.getViewCount()) {
                return getView(parent.getView(index), elem, start);
            }
            return null;
        }

  /*
   * If possible acquires a lock on the Document.  If a lock has been
   * obtained a key will be retured that should be passed to
   * <code>unlock</code>.
   */
  private Object lock(JEditorPane editor) {
      Document document = editor.getDocument();
     
      if (document instanceof AbstractDocument) {
    ((AbstractDocument)document).readLock();
    return document;
      }
      return null;
  }
 
  /*
   * Releases a lock previously obtained via <code>lock</code>.
   */
  private void unlock(Object key) {
      if (key != null) {
    ((AbstractDocument)key).readUnlock();
      }
  }

        /*
   * The operation to perform when this action is triggered.
   */
        public void actionPerformed(ActionEvent e) {

            JTextComponent c = getTextComponent(e);
      if (c.isEditable() || !(c instanceof JEditorPane)) {
    return;
      }
      JEditorPane editor = (JEditorPane)c;
     
      Document d = editor.getDocument();
      if (d == null || !(d instanceof HTMLDocument)) {
    return;
      }
      HTMLDocument doc = (HTMLDocument)d;

      ElementIterator ei = new ElementIterator(doc);
      int currentOffset = editor.getCaretPosition();

      // invoke the next link or object action
      String urlString = null;
      String objString = null;
      Element currentElement = null;
      while ((currentElement = ei.next()) != null) {
    String name = currentElement.getName();
    AttributeSet attr = currentElement.getAttributes();
   
    Object href = getAttrValue(attr, HTML.Attribute.HREF);
    if (href != null) {
        if (currentOffset >= currentElement.getStartOffset() &&
      currentOffset <= currentElement.getEndOffset()) {
     
      activateLink((String)href, doc, editor, currentOffset);
      return;
        }
    } else if (name.equals(HTML.Tag.OBJECT.toString())) {
        Object obj = getAttrValue(attr, HTML.Attribute.CLASSID);
        if (obj != null) {
      if (currentOffset >= currentElement.getStartOffset() &&
          currentOffset <= currentElement.getEndOffset()) {
         
          doObjectAction(editor, currentElement);
          return;
      }
        }
    }
      }
  }
    }

    private static int getBodyElementStart(JTextComponent comp) {
        Element rootElement = comp.getDocument().getRootElements()[0];
        for (int i = 0; i < rootElement.getElementCount(); i++) {
            Element currElement = rootElement.getElement(i);
            if("body".equals(currElement.getName())) {
                return currElement.getStartOffset();
            }
        }
        return 0;
    }
   
    /*
     * Move the caret to the beginning of the document.
     * @see DefaultEditorKit#beginAction
     * @see HTMLEditorKit#getActions
     */
   
    static class BeginAction extends TextAction {

        /* Create this object with the appropriate identifier. */
        BeginAction(String nm, boolean select) {
            super(nm);
            this.select = select;
        }

        /** The operation to perform when this action is triggered. */
        public void actionPerformed(ActionEvent e) {
            JTextComponent target = getTextComponent(e);
            int bodyStart = getBodyElementStart(target);
           
            if (target != null) {
                if (select) {
                    target.moveCaretPosition(bodyStart);
                } else {
                    target.setCaretPosition(bodyStart);
                }
            }
        }

        private boolean select;
    }
}
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