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/*
* Copyright 1999-2005 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id$ */
package org.apache.fop.image.analyser;
// Java
import java.io.InputStream;
import java.io.IOException;
// FOP
import org.apache.fop.image.FopImage;
import org.apache.fop.apps.FOUserAgent;
/**
* ImageReader object for JPEG image type.
*
* @author Pankaj Narula
* @version $Id$
*/
public class JPEGReader implements ImageReader {
/**
* 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.
*/
private static final int MARK = 0xff; // Beginning of a Marker
private static final int NULL = 0x00; // Special case for 0xff00
private static final int SOF1 = 0xc0; // Baseline DCT
private static final int SOF2 = 0xc1; // Extended Sequential DCT
private static final int SOF3 = 0xc2; // Progrssive DCT only PDF 1.3
private static final int SOFA = 0xca; // Progressice DCT only PDF 1.3
private static final int APP0 = 0xe0; // Application marker, JFIF
private static final int APPF = 0xef; // Application marker
private static final int SOS = 0xda; // Start of Scan
private static final int SOI = 0xd8; // start of Image
private static final int JPG_SIG_LENGTH = 2;
/** @see org.apache.fop.image.analyser.ImageReader */
public FopImage.ImageInfo verifySignature(String uri, InputStream fis,
FOUserAgent ua) throws IOException {
byte[] header = getDefaultHeader(fis);
boolean supported = ((header[0] == (byte) 0xff)
&& (header[1] == (byte) 0xd8));
if (supported) {
FopImage.ImageInfo info = getDimension(fis);
info.originalURI = uri;
info.mimeType = getMimeType();
info.inputStream = fis;
return info;
} else {
return null;
}
}
/**
* Returns the MIME type supported by this implementation.
*
* @return The MIME type
*/
public String getMimeType() {
return "image/jpeg";
}
private byte[] getDefaultHeader(InputStream imageStream) throws IOException {
byte[] header = new byte[JPG_SIG_LENGTH];
try {
imageStream.mark(JPG_SIG_LENGTH + 1);
imageStream.read(header);
imageStream.reset();
} catch (IOException ex) {
try {
imageStream.reset();
} catch (IOException exbis) {
// throw the original exception, not this one
}
throw ex;
}
return header;
}
private FopImage.ImageInfo getDimension(InputStream imageStream) throws IOException {
FopImage.ImageInfo info = new FopImage.ImageInfo();
try {
int pos=0, avail = imageStream.available();
imageStream.mark(avail);
int marker = NULL;
long length, skipped;
outer:
while (true) {
do {
if (avail == 0) {
imageStream.reset();
avail = 2*pos;
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
//Marker first byte (FF)
marker = imageStream.read();
pos++; avail--;
} while (marker != MARK);
do {
if (avail == 0) {
imageStream.reset();
avail = 2*pos;
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
//Marker second byte
marker = imageStream.read();
pos++; avail--;
} while (marker == MARK);
switch (marker) {
case SOI:
break;
case NULL:
break;
case APP0:
if (avail < 14) {
imageStream.reset();
avail = 2 * pos;
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
int reclen = this.read2bytes(imageStream);
pos += 2; avail -= 2;
this.skip(imageStream, 7);
pos += 7; avail -= 7;
int densityUnits = imageStream.read();
pos++; avail--;
int xdensity = this.read2bytes(imageStream);
pos += 2; avail -= 2;
int ydensity = this.read2bytes(imageStream);
pos += 2; avail -= 2;
if (densityUnits == 2) {
info.dpiHorizontal = xdensity * 28.3464567 / 72; //dpi
info.dpiVertical = ydensity * 28.3464567 / 72; //dpi
} else if (densityUnits == 1) {
info.dpiHorizontal = xdensity;
info.dpiVertical = ydensity;
} else {
//nop, nyi --> 72dpi
}
int restlen = reclen - 12;
if (avail < restlen) {
imageStream.reset();
avail = 2 * pos;
if (avail < pos + restlen + 10) {
avail = (int)(pos + restlen + 10);
}
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
skipped = this.skip(imageStream, restlen - 2);
pos += skipped; avail -= skipped;
if (skipped != restlen - 2) {
throw new IOException("Skipping Error");
}
break;
case SOF1:
case SOF2:
case SOF3: // SOF3 and SOFA are only supported by PDF 1.3
case SOFA:
while (avail < 7) {
imageStream.reset();
avail = 2*pos;
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
this.skip(imageStream, 3);
pos+=3; avail-=3;
info.height = this.read2bytes(imageStream);
pos+=2; avail-=2;
info.width = this.read2bytes(imageStream);
pos+=2; avail-=2;
break outer;
default:
while (avail < 2) {
imageStream.reset();
avail = 2*pos;
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
length = this.read2bytes(imageStream);
pos+=2; avail-=2;
if (avail < length) {
imageStream.reset();
avail = 2*pos;
if (avail < pos+length+10) {
avail = (int)(pos+length+10);
}
imageStream.mark(avail);
pos = (int)this.skip(imageStream, pos);
avail -= pos;
}
skipped = this.skip(imageStream, length - 2);
pos += skipped; avail -= skipped;
if (skipped != length - 2) {
throw new IOException("Skipping Error");
}
}
}
imageStream.reset();
} catch (IOException ioe) {
try {
imageStream.reset();
} catch (IOException exbis) {
// throw the original exception, not this one
}
throw ioe;
}
return info;
}
private int read2bytes(InputStream imageStream) throws IOException {
int byte1 = imageStream.read();
int byte2 = imageStream.read();
return (int) ((byte1 << 8) | byte2);
}
private long skip(InputStream imageStream, long n) throws IOException {
long discarded = 0;
while (discarded != n) {
imageStream.read();
discarded++;
}
return discarded; // scope for exception
}
}
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