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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 PNG image type.
*
* @author Pankaj Narula
* @version $Id$
*/
public class PNGReader implements ImageReader {
private static final int PNG_SIG_LENGTH = 24;
/** {@inheritDoc} */
public FopImage.ImageInfo verifySignature(String uri, InputStream bis,
FOUserAgent ua) throws IOException {
byte[] header = getDefaultHeader(bis);
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) {
FopImage.ImageInfo info = new FopImage.ImageInfo();
info.dpiHorizontal = ua.getFactory().getSourceResolution();
info.dpiVertical = info.dpiHorizontal;
getDimension(header, info);
info.originalURI = uri;
info.mimeType = getMimeType();
info.inputStream = bis;
return info;
} else {
return null;
}
}
/**
* Returns the MIME type supported by this implementation.
*
* @return The MIME type
*/
public String getMimeType() {
return "image/png";
}
private void getDimension(byte[] header, FopImage.ImageInfo info) {
// 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));
info.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);
info.height = (int) l;
}
private byte[] getDefaultHeader(InputStream imageStream)
throws IOException {
byte[] header = new byte[PNG_SIG_LENGTH];
try {
imageStream.mark(PNG_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;
}
}
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