---------------------------------------------------------------------------      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.      This software is provided "as is," without warranty of any kind,      express or implied.  In no event shall the author or contributors      be held liable for any damages arising in any way from the use of      this software.      The contents of this file are DUAL-LICENSED.  You may modify and/or      redistribute this software according to the terms of one of the      following two licenses (at your option):      LICENSE 1 ("BSD-like with advertising clause"):      Permission is granted to anyone to use this software for any purpose,      including commercial applications, and to alter it and redistribute      it freely, subject to the following restrictions:      1. Redistributions of source code must retain the above copyright         notice, disclaimer, and this list of conditions.      2. Redistributions in binary form must reproduce the above copyright         notice, disclaimer, and this list of conditions in the documenta-         tion and/or other materials provided with the distribution.      3. All advertising materials mentioning features or use of this         software must display the following acknowledgment:            This product includes software developed by Greg Roelofs            and contributors for the book, "PNG: The Definitive Guide,"            published by O'Reilly and Associates.      LICENSE 2 (GNU GPL v2 or later):      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 2 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, write to the Free Software Foundation,      Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  ---------------------------------------------------------------------------