Java example source code file (HTMLEditorKit.java)

This example Java source code file (HTMLEditorKit.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attributeset, awt, badlocationexception, element, event, gui, htmldocument, htmleditorkit, hyperlinkevent, inserthtmltextaction, jeditorpane, net, network, object, parser, rectangle, shape, string, swing, url

The HTMLEditorKit.java Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package javax.swing.text.html;

import sun.awt.AppContext;

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>
 * <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.
 * Its documentation describes the details of how the HTML is modeled.
 * The editing support leverages heavily off of the text package.
 *
 * <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 replaceable.  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 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>
 *
 * <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.
 * This is controlled by a property on the document.  The method
 * {@link #createDefaultDocument createDefaultDocument} can
 * be overriden to change this.  The batching of work is done
 * by the <code>HTMLDocument.HTMLReader class.  The actual
 * work is done by the <code>DefaultStyledDocument and
 * <code>AbstractDocument classes in the text package.
 *
 * <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
 * class.  The presentation of the HTML can be heavily influenced
 * by the setting of the StyleSheet property on the EditorKit.
 *
 * <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
 */
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.
     *
     * @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;
    }

    /**
     * Try to get an HTML parser from the document.  If no parser is set for
     * the document, return the editor kit's default parser.  It is an error
     * if no parser could be obtained from the editor kit.
     */
    private Parser ensureParser(HTMLDocument doc) throws IOException {
        Parser p = doc.getParser();
        if (p == null) {
            p = getParser();
        }
        if (p == null) {
            throw new IOException("Can't load parser");
        }
        return p;
    }

    /**
     * Inserts content from the given stream. If <code>doc 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;
            if (pos > doc.getLength()) {
                throw new BadLocationException("Invalid location", pos);
            }

            Parser p = ensureParser(hdoc);
            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 {
        if (offset > doc.getLength()) {
            throw new BadLocationException("Invalid location", offset);
        }

        Parser p = ensureParser(doc);
        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) {
        if (s == null) {
            AppContext.getAppContext().remove(DEFAULT_STYLES_KEY);
        } else {
            AppContext.getAppContext().put(DEFAULT_STYLES_KEY, 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() {
        AppContext appContext = AppContext.getAppContext();
        StyleSheet defaultStyles = (StyleSheet) appContext.get(DEFAULT_STYLES_KEY);

        if (defaultStyles == null) {
            defaultStyles = new StyleSheet();
            appContext.put(DEFAULT_STYLES_KEY, defaultStyles);
            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>elements AttributeSet into
     * <code>set. 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.

     * 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 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 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 final Object DEFAULT_STYLES_KEY = new Object();
    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() && editor.isEnabled() &&
                    SwingUtilities.isLeftMouseButton(e)) {
                Point pt = new Point(e.getX(), e.getY());
                int pos = editor.viewToModel(pt);
                if (pos >= 0) {
                    activateLink(pos, editor, e);
                }
            }
        }

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

        // track the moving of the mouse.
        public void mouseMoved(MouseEvent e) {
            JEditorPane editor = (JEditorPane) e.getSource();
            if (!editor.isEnabled()) {
                return;
            }

            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, e);
                            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 contains
         * the location <code>x, y. offset
         * 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, null);
        }

        /**
         * Calls linkActivated on the associated JEditorPane
         * if the given position represents a link. If this was the result
         * of a mouse click, <code>x and
         * <code>y will give the location of the mouse, otherwise
         * they will be {@literal <} 0.
         *
         * @param pos the position
         * @param html the editor pane
         */
        void activateLink(int pos, JEditorPane html, MouseEvent mouseEvent) {
            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;
                int x = -1;
                int y = -1;

                if (mouseEvent != null) {
                    x = mouseEvent.getX();
                    y = mouseEvent.getY();
                }

                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, mouseEvent);
                }
                if (linkEvent != null) {
                    html.fireHyperlinkUpdate(linkEvent);
                }
            }
        }

        /**
         * Creates and returns a new instance of HyperlinkEvent. If
         * <code>hdoc is a frame document a HTMLFrameHyperlinkEvent
         * will be created.
         */
        HyperlinkEvent createHyperlinkEvent(JEditorPane html,
                                            HTMLDocument hdoc, String href,
                                            AttributeSet anchor,
                                            Element element,
                                            MouseEvent mouseEvent) {
            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;

            if (!hdoc.isFrameDocument()) {
                linkEvent = new HyperlinkEvent(
                        html, HyperlinkEvent.EventType.ACTIVATED, u, href,
                        element, mouseEvent);
            } 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, mouseEvent, target);
            }
            return linkEvent;
        }

        void fireEvents(JEditorPane editor, HTMLDocument doc, String href,
                        Element lastElem, MouseEvent mouseEvent) {
            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, mouseEvent);
                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, mouseEvent);
                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 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 '<>foo<\t>'
         * 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. eol 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