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/* Copyright (c) 2015, David A. Clunie DBA Pixelmed Publishing. All rights reserved. */
package com.pixelmed.imageio;
// follow the pattern described in "http://docs.oracle.com/javase/1.5.0/docs/guide/imageio/spec/extending.fm3.html"
import com.pixelmed.codec.jpeg.Markers;
import com.pixelmed.codec.jpeg.Utilities;
import java.io.IOException;
import java.util.Locale;
import javax.imageio.ImageReader;
import javax.imageio.spi.ImageReaderSpi;
import javax.imageio.stream.ImageInputStream;
public class JPEGLosslessImageReaderSpi extends ImageReaderSpi {
private static final String identString = "@(#) $Header: /userland/cvs/codec/com/pixelmed/imageio/JPEGLosslessImageReaderSpi.java,v 1.5 2016/01/16 15:07:52 dclunie Exp $";
static final String vendorName = "PixelMed Publishing, LLC.";
static final String version = "0.01";
static final String readerClassName = "com.pixelmed.imageio.JPEGLosslessImageReader";
static final String description = "PixelMed JPEG Lossless Image Reader";
public static final Class<?>[] inputTypes = { ImageInputStream.class }; // current JavaDoc says STANDARD_INPUT_TYPE is deprecated
static final String[] names = { "jpeg-lossless" }; // this is what Sun JIIO JAI codecs use to recognize JPEG lossless
static final String[] suffixes = { "ljpeg", "jpl" }; // not "jls", which is JPEG-LS; "ljpeg" was used by USF Mammo
static final String[] MIMETypes = null; // current JavaDoc says null or empty array OK
static final String nativeImageMetadataFormatName = "com.pixelmed.imageio.JPEGLosslessMetadata_0.1";
static final String nativeImageMetadataFormatClassName = "com.pixelmed.imageio.JPEGLosslessMetadata";
public JPEGLosslessImageReaderSpi() {
super(
vendorName,
version,
names,
suffixes,
MIMETypes,
readerClassName,
inputTypes,
null/*writerSpiNames*/,
false/*supportsStandardStreamMetadataFormat*/,
null/*nativeStreamMetadataFormatName*/,
null/*nativeStreamMetadataFormatClassName*/,
null/*extraStreamMetadataFormatNames*/,
null/*extraStreamMetadataFormatClassNames*/,
false/*supportsStandardImageMetadataFormat*/,
nativeImageMetadataFormatName,
nativeImageMetadataFormatClassName,
null/*extraImageMetadataFormatNames*/,
null/*extraImageMetadataFormatClassNames*/);
}
public boolean canDecodeInput(Object input) throws IOException {
// Need SOI Start of Image
// May be intervening table/misc segments
// Need SOF3 Huffman Lossless Sequential length variable 0x0b
boolean canDecode = false;
try {
if (input instanceof ImageInputStream) {
ImageInputStream stream = (ImageInputStream)input;
byte[] b = new byte[4];
stream.mark();
stream.readFully(b,0,2);
if (b[0] == (byte)0xff && b[1] == (byte)0xd8) { // have SOI
int markerprefix = stream.read();
while (markerprefix == 0xff) { // keep reading until we have an SOF or until not a marker segment
int marker = stream.read();
marker|=0xff00; // convention is to express them with the leading ff, so that is what we look up
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): have marker "+Utilities.toPaddedHexString(marker,4)+" "+Markers.getAbbreviation(marker));
// should not have to worry about stuffed bytes in ECS or padding because we never get that far in the stream
if (Markers.isSOF(marker)) {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): have some type of SOF marker");
if (marker == Markers.SOF3) {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): have SOF3");
canDecode = true;
}
break; // stop reading after any SOF
}
else if (marker == Markers.SOS) {
break; // stop reading at SOS since too late to get SOF3
}
else if (Markers.isVariableLengthJPEGSegment(marker)) {
stream.readFully(b,0,2);
int length=((b[0]&0xff)<<8) + (b[1]&0xff); // big endian
if (length > 2) {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): skipping variable length marker segment length="+length);
stream.skipBytes(length-2);
}
else {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): variable length marker segment with invalid length="+length);
break;
}
}
else if (Markers.isNoLengthJPEGSegment(marker)) {
}
else {
int length=Markers.isFixedLengthJPEGSegment(marker);
if (length == 0) {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): stopping on unrecognized marker segment");
break;
}
else {
//System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput(): skipping fixed length marker segment length="+length);
stream.skipBytes(length-2);
}
}
markerprefix=stream.read();
}
}
// else no SOI so not JPEG
stream.reset();
System.err.println("JPEGLosslessImageReaderSpi.canDecodeInput() = "+canDecode);
}
}
catch (IOException e) {
}
return canDecode;
}
public String getDescription(Locale locale) {
return description;
}
public ImageReader createReaderInstance(Object extension) {
return new JPEGLosslessImageReader(this);
}
}
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