LengthDocumentFilter.java

/*
 *  UFO Saved Game Editor
 *  Copyright (C) 2010 Christopher Davoren
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 * 
 *  This program 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 for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.rubikscomplex.ufosge.gui;

import java.awt.Toolkit;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;


/**
 * Based off the DocumentSizeFilter from the Java Swing tutorials located at:
 * http://download-llnw.oracle.com/javase/tutorial/uiswing/index.html .
 *
 * @author Chris Davoren
 */
public class LengthDocumentFilter extends DocumentFilter {
    int maxCharacters;

    public LengthDocumentFilter(int maxCharacters) {
        super();
        this.maxCharacters = maxCharacters;
    }

    @Override
    public void insertString(FilterBypass fb, int offs,
                             String str, AttributeSet a)
        throws BadLocationException {

        //This rejects the entire insertion if it would make
        //the contents too long. Another option would be
        //to truncate the inserted string so the contents
        //would be exactly maxCharacters in length.
        if ((fb.getDocument().getLength() + str.length()) <= maxCharacters)
            super.insertString(fb, offs, str, a);
        else
            Toolkit.getDefaultToolkit().beep();
    }

    @Override
    public void replace(FilterBypass fb, int offs,
                        int length,
                        String str, AttributeSet a)
        throws BadLocationException {

        //This rejects the entire replacement if it would make
        //the contents too long. Another option would be
        //to truncate the replacement string so the contents
        //would be exactly maxCharacters in length.
        if ((fb.getDocument().getLength() + str.length()
             - length) <= maxCharacters)
            super.replace(fb, offs, length, str, a);
        else
            Toolkit.getDefaultToolkit().beep();
    }
}