001/* ========================================================================
002 * JCommon : a free general purpose class library for the Java(tm) platform
003 * ========================================================================
004 *
005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006 * 
007 * Project Info:  http://www.jfree.org/jcommon/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it 
010 * under the terms of the GNU Lesser General Public License as published by 
011 * the Free Software Foundation; either version 2.1 of the License, or 
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but 
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022 * USA.  
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025 * in the United States and other countries.]
026 * 
027 * ---------------------------
028 * LengthLimitingDocument.java
029 * ---------------------------
030 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
031 *
032 * Original Author:  Thomas Morgner;
033 * Contributor(s):   David Gilbert (for Object Refinery Limited);
034 *
035 * $Id: LengthLimitingDocument.java,v 1.3 2005/10/18 13:18:34 mungady Exp $
036 *
037 * Changes
038 * -------
039 * 22-Jan-2003 : Initial version
040 * 05-Feb-2003 : Documentation
041 * 
042 */
043
044package org.jfree.ui;
045
046import javax.swing.text.AttributeSet;
047import javax.swing.text.BadLocationException;
048import javax.swing.text.PlainDocument;
049
050/**
051 * This Document restricts the size of the contained plain text to the given number of
052 * characters.
053 *
054 * @author Thomas Morgner
055 */
056public class LengthLimitingDocument extends PlainDocument {
057
058    /** The maximum length. */
059    private int maxlen;
060
061    /**
062     * Creates a new LengthLimitingDocument, with no limitation.
063     */
064    public LengthLimitingDocument() {
065        this(-1);
066    }
067
068    /**
069     * Creates a new LengthLimitingDocument with the given limitation. No more than
070     * maxlen characters can be added to the document. If maxlen is negative, then
071     * no length check is performed.
072     *
073     * @param maxlen the maximum number of elements in this document
074     */
075    public LengthLimitingDocument(final int maxlen) {
076        super();
077        this.maxlen = maxlen;
078    }
079
080    /**
081     * Sets the maximum number of characters for this document. Existing characters
082     * are not removed.
083     *
084     * @param maxlen the maximum number of characters in this document.
085     */
086    public void setMaxLength(final int maxlen) {
087        this.maxlen = maxlen;
088    }
089
090    /**
091     * Returns the defined maximum number characters for this document.
092     * @return the maximum number of characters
093     */
094    public int getMaxLength() {
095        return this.maxlen;
096    }
097
098    /**
099     * Inserts the string into the document. If the length of the document would
100     * violate the maximum characters restriction, then the string is cut down so
101     * that
102     * @param offs the offset, where the string should be inserted into the document
103     * @param str the string that should be inserted
104     * @param a the attribute set assigned for the document
105     * @throws javax.swing.text.BadLocationException if the offset is not correct
106     */
107    public void insertString(final int offs, final String str, final AttributeSet a)
108        throws BadLocationException {
109        if (str == null) {
110            return;
111        }
112
113        if (this.maxlen < 0) {
114            super.insertString(offs, str, a);
115        }
116
117        final char[] numeric = str.toCharArray();
118        final StringBuffer b = new StringBuffer();
119        b.append(numeric, 0, Math.min(this.maxlen, numeric.length));
120        super.insertString(offs, b.toString(), a);
121    }
122    
123}