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Posted to fop-commits@xmlgraphics.apache.org by es...@locus.apache.org on 2000/08/11 16:27:10 UTC
cvs commit: xml-fop/src/org/apache/fop/image/analyser JPEGReader.java
eschaeffer 00/08/11 07:27:10
Added: src/org/apache/fop/image/analyser JPEGReader.java
Log:
ImageReader implementing class for JPEG images
Revision Changes Path
1.1 xml-fop/src/org/apache/fop/image/analyser/JPEGReader.java
Index: JPEGReader.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 JPEG image type.
* @author Pankaj Narula
* @version 1.0
*/
public class JPEGReader extends AbstractImageReader {
/**
* Only SOFn and APPn markers are defined as SOFn is needed for the height and
* width search. APPn is also defined because if the JPEG contains thumbnails
* the dimensions of the thumnail would also be after the SOFn marker enclosed
* inside the APPn marker. And we don't want to confuse those dimensions with
* the image dimensions.
*/
static protected final int MARK = 0xff; //Beginneing of a Marker
static protected final int NULL = 0x00; //Special case for 0xff00
static protected final int SOF1 = 0xc0; //Baseline DCT
static protected final int SOF2 = 0xc1; //Extended Sequential DCT
static protected final int SOF3 = 0xc2; //Progrssive DCT only PDF 1.3
static protected final int SOFA = 0xca; //Progressice DCT only PDF 1.3
static protected final int APP0 = 0xe0; //Application marker, JFIF
static protected final int APPF = 0xef; //Application marker
static protected final int SOS = 0xda; //Start of Scan
static protected final int SOI = 0xd8; //start of Image
static protected final int JPG_SIG_LENGTH = 2;
protected byte[] header;
public boolean verifySignature(BufferedInputStream fis)
throws IOException {
this.imageStream = fis;
this.setDefaultHeader();
boolean supported = ((header[0] == (byte) 0xff) &&
(header[1] == (byte) 0xd8));
if (supported) {
setDimension();
return true;
} else
return false;
}
public String getMimeType() {
return "image/jpeg";
}
protected void setDefaultHeader() throws IOException {
this.header = new byte[JPG_SIG_LENGTH];
try {
this.imageStream.mark(JPG_SIG_LENGTH + 1);
this.imageStream.read(header);
this.imageStream.reset();
} catch (IOException ex) {
try {
this.imageStream.reset();
} catch (IOException exbis) {}
throw ex;
}
}
protected void setDimension() throws IOException {
try {
int marker = NULL;
long length, skipped;
outer:
while (imageStream.available() > 0) {
while ((marker = imageStream.read()) != MARK) {
;
}
do {
marker = imageStream.read();
} while (marker == MARK)
;
switch (marker) {
case SOI :
break;
case NULL:
break;
case SOF1:
case SOF2:
case SOF3: //SOF3 and SOFA are only supported by PDF 1.3
case SOFA:
this.skip(3);
this.height = this.read2bytes();
this.width = this.read2bytes();
break outer;
default:
length = this.read2bytes();
skipped = this.skip(length - 2);
if (skipped != length - 2)
throw new IOException("Skipping Error");
}
}
} catch (IOException ioe) {
try {
this.imageStream.reset();
} catch (IOException exbis) {}
throw ioe;
}
}
protected int read2bytes() throws IOException {
int byte1 = imageStream.read();
int byte2 = imageStream.read();
return (int)((byte1 << 8) | byte2);
}
protected long skip(long n) throws IOException {
long discarded = 0;
while (discarded != n) {
imageStream.read();
discarded++;
}
return discarded; //scope for exception
}
}