cvs commit: xml-fop/src/org/apache/fop/image/analyser PNGReader.java

[es...@locus.apache.org]

eschaeffer    00/08/11 07:28:27

  Added:       src/org/apache/fop/image/analyser PNGReader.java
  Log:
  ImageReader implementing class for PNG images
  
  Revision  Changes    Path
  1.1                  xml-fop/src/org/apache/fop/image/analyser/PNGReader.java
  
  Index: PNGReader.java
  ===================================================================
  /*
   ============================================================================
                     The Apache Software License, Version 1.1
   ============================================================================
      Copyright (C) 1999 The Apache Software Foundation. All rights reserved.
   Redistribution and use in source and binary forms, with or without modifica-
   tion, are permitted provided that the following conditions are met:
   1. Redistributions of  source code must  retain the above copyright  notice,
      this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
   3. The end-user documentation included with the redistribution, if any, must
      include  the following  acknowledgment:  "This product includes  software
      developed  by the  Apache Software Foundation  (http://www.apache.org/)."
      Alternately, this  acknowledgment may  appear in the software itself,  if
      and wherever such third-party acknowledgments normally appear.
   4. The names "Fop" and  "Apache Software Foundation"  must not be used to
      endorse  or promote  products derived  from this  software without  prior
      written permission. For written permission, please contact
      apache@apache.org.
   5. Products  derived from this software may not  be called "Apache", nor may
      "Apache" appear  in their name,  without prior written permission  of the
      Apache Software Foundation.
   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
   INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
   APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
   INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLU-
   DING, BUT NOT LIMITED TO, PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS
   OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND ON
   ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR TORT
   (INCLUDING  NEGLIGENCE OR  OTHERWISE) ARISING IN  ANY WAY OUT OF THE  USE OF
   THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   This software  consists of voluntary contributions made  by many individuals
   on  behalf of the Apache Software  Foundation and was  originally created by
   James Tauber <jt...@jtauber.com>. For more  information on the Apache
   Software Foundation, please see <http://www.apache.org/>.
   */
  
  package org.apache.fop.image.analyser;
  
  // Java
  import java.io.BufferedInputStream;
  import java.io.IOException;
  
  /**
   * ImageReader object for PNG image type.
   * @author Pankaj Narula
   * @version 1.0
   */
  public class PNGReader extends AbstractImageReader {
    static protected final int PNG_SIG_LENGTH = 24;
    protected byte[] header;
  
    public boolean verifySignature(BufferedInputStream fis) throws IOException {
      this.imageStream = fis;
      this.setDefaultHeader();
      boolean supported = ((header[0] == (byte) 0x89) &&
                           (header[1] == (byte) 0x50) &&
                           (header[2] == (byte) 0x4e) &&
                           (header[3] == (byte) 0x47) &&
                           (header[4] == (byte) 0x0d) &&
                           (header[5] == (byte) 0x0a) &&
                           (header[6] == (byte) 0x1a) &&
                           (header[7] == (byte) 0x0a));
      if (supported) {
        setDimension();
        return true;
      } else
        return false;
    }
  
    public String getMimeType() {
      return "image/png";
    }
  
    protected void setDimension() {
      //png is always big endian
      int byte1 = header[16] & 0xff;
      int byte2 = header[17] & 0xff;
      int byte3 = header[18] & 0xff;
      int byte4 = header[19] & 0xff;
      long l = (long)((byte1 << 24) | (byte2 << 16) |
                      (byte3 << 8) | byte4);
      this.width = (int)(l);
  
      byte1 = header[20] & 0xff;
      byte2 = header[21] & 0xff;
      byte3 = header[22] & 0xff;
      byte4 = header[23] & 0xff;
      l = (long)((byte1 << 24) | (byte2 << 16) | (byte3 << 8) |
                 byte4);
      this.height = (int)(l);
  
    }
  
    protected void setDefaultHeader() throws IOException {
      this.header = new byte[PNG_SIG_LENGTH];
      try {
        this.imageStream.mark(PNG_SIG_LENGTH + 1);
        this.imageStream.read(header);
        this.imageStream.reset();
      } catch (IOException ex) {
        try {
          this.imageStream.reset();
        } catch (IOException exbis) {}
        throw ex;
      }
    }
  }