/*
* Early versions of this class were inspired by Jhead, a C program for extracting and
* manipulating the Exif data within files written by Matthias Wandel.
* http://www.sentex.net/~mwandel/jhead/
*
* Jhead is public domain software - that is, you can do whatever you want
* with it, and include it software that is licensed under the GNU or the
* BSD license, or whatever other licence you choose, including proprietary
* closed source licenses. Similarly, I release this Java version under the
* same license, though I do ask that you leave this header in tact.
*
* If you make modifications to this code that you think would benefit the
* wider community, please send me a copy and I'll post it on my site. Unlike
* Jhead, this code (as it stands) only supports reading of Exif data - no
* manipulation.
*
* If you make use of this code, I'd appreciate hearing about it.
* drew.noakes@drewnoakes.com
* Latest version of this software kept at
* http://drewnoakes.com/
*
* Created on 28 April 2002, 23:54
* Modified 04 Aug 2002
* - Renamed constants to be inline with changes to ExifTagValues interface
* - Substituted usage of JDK 1.4 features (java.nio package)
* Modified 29 Oct 2002 (v1.2)
* - Proper traversing of Exif file structure and complete refactor & tidy of
* the codebase (a few unnoticed bugs removed)
* - Reads makernote data for 6 families of camera (5 makes)
* - Tags now stored in directories... use the IFD_* constants to refer to the
* image file directory you require (Exif, Interop, GPS and Makernote*) --
* this avoids collisions where two tags share the same code
* - Takes componentCount of unknown tags into account
* - Now understands GPS tags (thanks to Colin Briton for his help with this)
* - Some other bug fixes, pointed out by users around the world. Thanks!
* Modified 27 Nov 2002 (v2.0)
* - Renamed to ExifReader
* - Moved to new package com.drew.metadata.exif
* Modified since, however changes have not been logged. See release notes for
* library-wide modifications.
*/
package com.drew.metadata.exif;
import com.drew.imaging.jpeg.JpegProcessingException;
import com.drew.imaging.jpeg.JpegSegmentData;
import com.drew.imaging.jpeg.JpegSegmentReader;
import com.drew.lang.Rational;
import com.drew.metadata.Directory;
import com.drew.metadata.Metadata;
import com.drew.metadata.MetadataReader;
import java.io.File;
import java.io.InputStream;
import java.util.HashMap;
/**
* Decodes Exif binary data, populating a <code>Metadata</code> object with tag values in <code>ExifDirectory</code>,
* <code>GpsDirectory</code> and one of the many camera makernote directories.
* @author Drew Noakes http://drewnoakes.com
*/
public class ExifReader implements MetadataReader
{
/**
* The number of bytes used per format descriptor.
*/
private static final int[] BYTES_PER_FORMAT = {0, 1, 1, 2, 4, 8, 1, 1, 2, 4, 8, 4, 8};
/**
* The number of formats known.
*/
private static final int MAX_FORMAT_CODE = 12;
// Format types
// Note: Cannot use the DataFormat enumeration in the case statement that uses these tags.
// Is there a better way?
private static final int FMT_BYTE = 1;
private static final int FMT_STRING = 2;
private static final int FMT_USHORT = 3;
private static final int FMT_ULONG = 4;
private static final int FMT_URATIONAL = 5;
private static final int FMT_SBYTE = 6;
private static final int FMT_UNDEFINED = 7;
private static final int FMT_SSHORT = 8;
private static final int FMT_SLONG = 9;
private static final int FMT_SRATIONAL = 10;
private static final int FMT_SINGLE = 11;
private static final int FMT_DOUBLE = 12;
public static final int TAG_EXIF_OFFSET = 0x8769;
public static final int TAG_INTEROP_OFFSET = 0xA005;
public static final int TAG_GPS_INFO_OFFSET = 0x8825;
public static final int TAG_MAKER_NOTE = 0x927C;
public static final int TIFF_HEADER_START_OFFSET = 6;
/**
* The Exif segment as an array of bytes.
*/
private final byte[] _data;
/**
* Represents the native byte ordering used in the JPEG segment. If true,
* then we're using Motorolla ordering (Big endian), else we're using Intel
* ordering (Little endian).
*/
private boolean _isMotorollaByteOrder;
/**
* Bean instance to store information about the image and camera/scanner/capture
* device.
*/
private Metadata _metadata;
/**
* The Exif directory used (loaded lazily)
*/
private ExifDirectory _exifDirectory = null;
/**
* Creates an ExifReader for a JpegSegmentData object.
* @param segmentData
* @deprecated Not all files will be Jpegs! This overload doesn't offer much convenience to the caller.
*/
public ExifReader(JpegSegmentData segmentData)
{
// TODO consider removing this constructor and requiring callers to pass a byte[] or other means to read the exif segment in isolation... not all files will be Jpegs!
this(segmentData.getSegment(JpegSegmentReader.SEGMENT_APP1));
}
/**
* Creates an ExifReader for a Jpeg jpegFile.
* @param jpegFile
* @throws JpegProcessingException
* @deprecated Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.
*/
public ExifReader(File jpegFile) throws JpegProcessingException
{
// TODO consider removing this constructor and requiring callers to pass a byte[] or other means to read the exif segment in isolation... not all files will be Jpegs!
this(new JpegSegmentReader(jpegFile).readSegment(JpegSegmentReader.SEGMENT_APP1));
}
/**
* Creates an ExifReader for a Jpeg stream.
* @param jpegInputStream JPEG stream. Stream will be closed.
* @deprecated Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.
*/
public ExifReader(InputStream jpegInputStream) throws JpegProcessingException
{
// TODO consider removing this constructor and requiring callers to pass a byte[] or other means to read the exif segment in isolation... not all files will be Jpegs!
this(new JpegSegmentReader(jpegInputStream).readSegment(JpegSegmentReader.SEGMENT_APP1));
}
/**
* Creates an ExifReader for the given Exif data segment.
*/
public ExifReader(byte[] data)
{
_data = data;
}
/**
* Performs the Exif data extraction, returning a new instance of <code>Metadata</code>.
*/
public Metadata extract()
{
return extract(new Metadata());
}
/**
* Performs the Exif data extraction, adding found values to the specified
* instance of <code>Metadata</code>.
*/
public Metadata extract(Metadata metadata)
{
_metadata = metadata;
if (_data==null)
return _metadata;
ExifDirectory directory = getExifDirectory();
// check for the header length
if (_data.length<=14) {
directory.addError("Exif data segment must contain at least 14 bytes");
return _metadata;
}
// check for the header preamble
if (!"Exif\0\0".equals(new String(_data, 0, 6))) {
directory.addError("Exif data segment doesn't begin with 'Exif'");
return _metadata;
}
return extractIFD(_metadata, TIFF_HEADER_START_OFFSET);
}
private ExifDirectory getExifDirectory()
{
if (_exifDirectory == null) {
_exifDirectory = (ExifDirectory)_metadata.getDirectory(ExifDirectory.class);
}
return _exifDirectory;
}
/**
* Performs the Exif data extraction on a Tiff/Raw, adding found values to the specified
* instance of <code>Metadata</code>.
*/
public Metadata extractTiff(Metadata metadata)
{
return extractIFD(metadata, 0);
}
private Metadata extractIFD(Metadata metadata, int tiffHeaderOffset)
{
_metadata = metadata;
if (_data==null)
return _metadata;
ExifDirectory directory = getExifDirectory();
// this should be either "MM" or "II"
String byteOrderIdentifier = new String(_data, tiffHeaderOffset, 2);
if (!setByteOrder(byteOrderIdentifier)) {
directory.addError("Unclear distinction between Motorola/Intel byte ordering: " + byteOrderIdentifier);
return _metadata;
}
// Check the next two values for correctness.
if (get16Bits(2+tiffHeaderOffset)!=0x2a) {
directory.addError("Invalid Exif start - should have 0x2A at offset 8 in Exif header");
return _metadata;
}
int firstDirectoryOffset = get32Bits(4+tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent an digital camera image that has this problem
if (firstDirectoryOffset>=_data.length - 1) {
directory.addError("First exif directory offset is beyond end of Exif data segment");
// First directory normally starts 14 bytes in -- try it here and catch another error in the worst case
firstDirectoryOffset = 14;
}
HashMap processedDirectoryOffsets = new HashMap();
// 0th IFD (we merge with Exif IFD)
processDirectory(directory, processedDirectoryOffsets, firstDirectoryOffset, tiffHeaderOffset);
// after the extraction process, if we have the correct tags, we may be able to store thumbnail information
storeThumbnailBytes(directory, tiffHeaderOffset);
return _metadata;
}
private void storeThumbnailBytes(ExifDirectory exifDirectory, int tiffHeaderOffset)
{
if (!exifDirectory.containsTag(ExifDirectory.TAG_COMPRESSION))
return;
if (!exifDirectory.containsTag(ExifDirectory.TAG_THUMBNAIL_LENGTH) ||
!exifDirectory.containsTag(ExifDirectory.TAG_THUMBNAIL_OFFSET))
return;
try {
int offset = exifDirectory.getInt(ExifDirectory.TAG_THUMBNAIL_OFFSET);
int length = exifDirectory.getInt(ExifDirectory.TAG_THUMBNAIL_LENGTH);
byte[] result = new byte[length];
for (int i = 0; i<result.length; i++) {
result[i] = _data[tiffHeaderOffset + offset + i];
}
exifDirectory.setByteArray(ExifDirectory.TAG_THUMBNAIL_DATA, result);
} catch (Throwable e) {
exifDirectory.addError("Unable to extract thumbnail: " + e.getMessage());
}
}
/**
* Sets the _isMotorollaByteOrder flag to true or false, depending upon the file's byte order
* string. If the string cannot be interpreted, false is returned.
* @param byteOrderIdentifier a two-character string; either "MM" for Motorolla or "II" for Intel.
* @return true if successful, otherwise false.
*/
private boolean setByteOrder(String byteOrderIdentifier)
{
if ("MM".equals(byteOrderIdentifier)) {
_isMotorollaByteOrder = true;
} else if ("II".equals(byteOrderIdentifier)) {
_isMotorollaByteOrder = false;
} else {
return false;
}
return true;
}
/**
* Process one of the nested Tiff IFD directories.
* 2 bytes: number of tags
* for each tag
* 2 bytes: tag type
* 2 bytes: format code
* 4 bytes: component count
*/
private void processDirectory(Directory directory, HashMap processedDirectoryOffsets, int dirStartOffset, int tiffHeaderOffset)
{
// check for directories we've already visited to avoid stack overflows when recursive/cyclic directory structures exist
if (processedDirectoryOffsets.containsKey(new Integer(dirStartOffset)))
return;
// remember that we've visited this directory so that we don't visit it again later
processedDirectoryOffsets.put(new Integer(dirStartOffset), "processed");
if (dirStartOffset>=_data.length || dirStartOffset<0) {
directory.addError("Ignored directory marked to start outside data segement");
return;
}
if (!isDirectoryLengthValid(dirStartOffset, tiffHeaderOffset)) {
directory.addError("Illegally sized directory");
return;
}
// First two bytes in the IFD are the number of tags in this directory
int dirTagCount = get16Bits(dirStartOffset);
// Handle each tag in this directory
for (int tagNumber = 0; tagNumber<dirTagCount; tagNumber++)
{
final int tagOffset = calculateTagOffset(dirStartOffset, tagNumber);
// 2 bytes for the tag type
final int tagType = get16Bits(tagOffset);
// 2 bytes for the format code
final int formatCode = get16Bits(tagOffset + 2);
if (formatCode<1 || formatCode>MAX_FORMAT_CODE) {
directory.addError("Invalid format code: " + formatCode);
continue;
}
// 4 bytes dictate the number of components in this tag's data
final int componentCount = get32Bits(tagOffset + 4);
if (componentCount<0) {
directory.addError("Negative component count in EXIF");
continue;
}
// each component may have more than one byte... calculate the total number of bytes
final int byteCount = componentCount * BYTES_PER_FORMAT[formatCode];
final int tagValueOffset = calculateTagValueOffset(byteCount, tagOffset, tiffHeaderOffset);
if (tagValueOffset<0 || tagValueOffset > _data.length) {
directory.addError("Illegal pointer offset value in EXIF");
continue;
}
// Check that this tag isn't going to allocate outside the bounds of the data array.
// This addresses an uncommon OutOfMemoryError.
if (byteCount < 0 || tagValueOffset + byteCount > _data.length)
{
directory.addError("Illegal number of bytes: " + byteCount);
continue;
}
// Calculate the value as an offset for cases where the tag represents directory
final int subdirOffset = tiffHeaderOffset + get32Bits(tagValueOffset);
switch (tagType) {
case TAG_EXIF_OFFSET:
processDirectory(_metadata.getDirectory(ExifDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
continue;
case TAG_INTEROP_OFFSET:
processDirectory(_metadata.getDirectory(ExifInteropDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
continue;
case TAG_GPS_INFO_OFFSET:
processDirectory(_metadata.getDirectory(GpsDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
continue;
case TAG_MAKER_NOTE:
processMakerNote(tagValueOffset, processedDirectoryOffsets, tiffHeaderOffset);
continue;
default:
processTag(directory, tagType, tagValueOffset, componentCount, formatCode);
break;
}
}
// at the end of each IFD is an optional link to the next IFD
final int finalTagOffset = calculateTagOffset(dirStartOffset, dirTagCount);
int nextDirectoryOffset = get32Bits(finalTagOffset);
if (nextDirectoryOffset!=0) {
nextDirectoryOffset += tiffHeaderOffset;
if (nextDirectoryOffset>=_data.length) {
// Last 4 bytes of IFD reference another IFD with an address that is out of bounds
// Note this could have been caused by jhead 1.3 cropping too much
return;
} else if (nextDirectoryOffset < dirStartOffset) {
// Last 4 bytes of IFD reference another IFD with an address that is before the start of this directory
return;
}
// the next directory is of same type as this one
processDirectory(directory, processedDirectoryOffsets, nextDirectoryOffset, tiffHeaderOffset);
}
}
private void processMakerNote(int subdirOffset, HashMap processedDirectoryOffsets, int tiffHeaderOffset)
{
// Determine the camera model and makernote format
Directory exifDirectory = _metadata.getDirectory(ExifDirectory.class);
if (exifDirectory==null)
return;
String cameraModel = exifDirectory.getString(ExifDirectory.TAG_MAKE);
final String firstTwoChars = new String(_data, subdirOffset, 2);
final String firstThreeChars = new String(_data, subdirOffset, 3);
final String firstFourChars = new String(_data, subdirOffset, 4);
final String firstFiveChars = new String(_data, subdirOffset, 5);
final String firstSixChars = new String(_data, subdirOffset, 6);
final String firstSevenChars = new String(_data, subdirOffset, 7);
final String firstEightChars = new String(_data, subdirOffset, 8);
if ("OLYMP".equals(firstFiveChars) || "EPSON".equals(firstFiveChars) || "AGFA".equals(firstFourChars))
{
// Olympus Makernote
// Epson and Agfa use Olypus maker note standard, see:
// http://www.ozhiker.com/electronics/pjmt/jpeg_info/
processDirectory(_metadata.getDirectory(OlympusMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 8, tiffHeaderOffset);
}
else if (cameraModel!=null && cameraModel.trim().toUpperCase().startsWith("NIKON"))
{
if ("Nikon".equals(firstFiveChars))
{
/* There are two scenarios here:
* Type 1: **
* :0000: 4E 69 6B 6F 6E 00 01 00-05 00 02 00 02 00 06 00 Nikon...........
* :0010: 00 00 EC 02 00 00 03 00-03 00 01 00 00 00 06 00 ................
* Type 3: **
* :0000: 4E 69 6B 6F 6E 00 02 00-00 00 4D 4D 00 2A 00 00 Nikon....MM.*...
* :0010: 00 08 00 1E 00 01 00 07-00 00 00 04 30 32 30 30 ............0200
*/
if (_data[subdirOffset+6]==1)
processDirectory(_metadata.getDirectory(NikonType1MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 8, tiffHeaderOffset);
else if (_data[subdirOffset+6]==2)
processDirectory(_metadata.getDirectory(NikonType2MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 18, subdirOffset + 10);
else
exifDirectory.addError("Unsupported makernote data ignored.");
}
else
{
// The IFD begins with the first MakerNote byte (no ASCII name). This occurs with CoolPix 775, E990 and D1 models.
processDirectory(_metadata.getDirectory(NikonType2MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
}
}
else if ("SONY CAM".equals(firstEightChars) || "SONY DSC".equals(firstEightChars))
{
processDirectory(_metadata.getDirectory(SonyMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 12, tiffHeaderOffset);
}
else if ("KDK".equals(firstThreeChars))
{
processDirectory(_metadata.getDirectory(KodakMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 20, tiffHeaderOffset);
}
else if ("Canon".equalsIgnoreCase(cameraModel))
{
processDirectory(_metadata.getDirectory(CanonMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
}
else if (cameraModel!=null && cameraModel.toUpperCase().startsWith("CASIO"))
{
if ("QVC\u0000\u0000\u0000".equals(firstSixChars))
processDirectory(_metadata.getDirectory(CasioType2MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 6, tiffHeaderOffset);
else
processDirectory(_metadata.getDirectory(CasioType1MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
}
else if ("FUJIFILM".equals(firstEightChars) || "Fujifilm".equalsIgnoreCase(cameraModel))
{
// TODO make this field a passed parameter, to avoid threading issues
boolean byteOrderBefore = _isMotorollaByteOrder;
// bug in fujifilm makernote ifd means we temporarily use Intel byte ordering
_isMotorollaByteOrder = false;
// the 4 bytes after "FUJIFILM" in the makernote point to the start of the makernote
// IFD, though the offset is relative to the start of the makernote, not the TIFF
// header (like everywhere else)
int ifdStart = subdirOffset + get32Bits(subdirOffset + 8);
processDirectory(_metadata.getDirectory(FujifilmMakernoteDirectory.class), processedDirectoryOffsets, ifdStart, tiffHeaderOffset);
_isMotorollaByteOrder = byteOrderBefore;
}
else if (cameraModel!=null && cameraModel.toUpperCase().startsWith("MINOLTA"))
{
// Cases seen with the model starting with MINOLTA in capitals seem to have a valid Olympus makernote
// area that commences immediately.
processDirectory(_metadata.getDirectory(OlympusMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset, tiffHeaderOffset);
}
else if ("KC".equals(firstTwoChars) || "MINOL".equals(firstFiveChars) || "MLY".equals(firstThreeChars) || "+M+M+M+M".equals(firstEightChars))
{
// This Konica data is not understood. Header identified in accordance with information at this site:
// http://www.ozhiker.com/electronics/pjmt/jpeg_info/minolta_mn.html
// TODO determine how to process the information described at the above website
exifDirectory.addError("Unsupported Konica/Minolta data ignored.");
}
else if ("KYOCERA".equals(firstSevenChars))
{
// http://www.ozhiker.com/electronics/pjmt/jpeg_info/kyocera_mn.html
processDirectory(_metadata.getDirectory(KyoceraMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 22, tiffHeaderOffset);
}
else if ("Panasonic\u0000\u0000\u0000".equals(new String(_data, subdirOffset, 12)))
{
// NON-Standard TIFF IFD Data using Panasonic Tags. There is no Next-IFD pointer after the IFD
// Offsets are relative to the start of the TIFF header at the beginning of the EXIF segment
// more information here: http://www.ozhiker.com/electronics/pjmt/jpeg_info/panasonic_mn.html
processDirectory(_metadata.getDirectory(PanasonicMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 12, tiffHeaderOffset);
}
else if ("AOC\u0000".equals(firstFourChars))
{
// NON-Standard TIFF IFD Data using Casio Type 2 Tags
// IFD has no Next-IFD pointer at end of IFD, and
// Offsets are relative to the start of the current IFD tag, not the TIFF header
// Observed for:
// - Pentax ist D
processDirectory(_metadata.getDirectory(CasioType2MakernoteDirectory.class), processedDirectoryOffsets, subdirOffset + 6, subdirOffset);
}
else if (cameraModel!=null && (cameraModel.toUpperCase().startsWith("PENTAX") || cameraModel.toUpperCase().startsWith("ASAHI")))
{
// NON-Standard TIFF IFD Data using Pentax Tags
// IFD has no Next-IFD pointer at end of IFD, and
// Offsets are relative to the start of the current IFD tag, not the TIFF header
// Observed for:
// - PENTAX Optio 330
// - PENTAX Optio 430
processDirectory(_metadata.getDirectory(PentaxMakernoteDirectory.class), processedDirectoryOffsets, subdirOffset, subdirOffset);
}
else
{
// TODO how to store makernote data when it's not from a supported camera model?
// this is difficult as the starting offset is not known. we could look for it...
exifDirectory.addError("Unsupported makernote data ignored.");
}
}
private boolean isDirectoryLengthValid(int dirStartOffset, int tiffHeaderOffset)
{
int dirTagCount = get16Bits(dirStartOffset);
int dirLength = (2 + (12 * dirTagCount) + 4);
if (dirLength + dirStartOffset + tiffHeaderOffset>=_data.length) {
// Note: Files that had thumbnails trimmed with jhead 1.3 or earlier might trigger this
return false;
}
return true;
}
private void processTag(Directory directory, int tagType, int tagValueOffset, int componentCount, int formatCode)
{
// Directory simply stores raw values
// The display side uses a Descriptor class per directory to turn the raw values into 'pretty' descriptions
switch (formatCode)
{
case FMT_UNDEFINED:
// this includes exif user comments
final byte[] tagBytes = new byte[componentCount];
final int byteCount = componentCount * BYTES_PER_FORMAT[formatCode];
for (int i=0; i<byteCount; i++)
tagBytes[i] = _data[tagValueOffset + i];
directory.setByteArray(tagType, tagBytes);
break;
case FMT_STRING:
directory.setString(tagType, readString(tagValueOffset, componentCount));
break;
case FMT_SRATIONAL:
case FMT_URATIONAL:
if (componentCount==1) {
Rational rational = new Rational(get32Bits(tagValueOffset), get32Bits(tagValueOffset + 4));
directory.setRational(tagType, rational);
} else {
Rational[] rationals = new Rational[componentCount];
for (int i = 0; i<componentCount; i++)
rationals[i] = new Rational(get32Bits(tagValueOffset + (8 * i)), get32Bits(tagValueOffset + 4 + (8 * i)));
directory.setRationalArray(tagType, rationals);
}
break;
case FMT_SBYTE:
case FMT_BYTE:
if (componentCount==1) {
// this may need to be a byte, but I think casting to int is fine
int b = _data[tagValueOffset];
directory.setInt(tagType, b);
} else {
int[] bytes = new int[componentCount];
for (int i = 0; i<componentCount; i++)
bytes[i] = _data[tagValueOffset + i];
directory.setIntArray(tagType, bytes);
}
break;
case FMT_SINGLE:
case FMT_DOUBLE:
if (componentCount==1) {
int i = _data[tagValueOffset];
directory.setInt(tagType, i);
} else {
int[] ints = new int[componentCount];
for (int i = 0; i<componentCount; i++)
ints[i] = _data[tagValueOffset + i];
directory.setIntArray(tagType, ints);
}
break;
case FMT_USHORT:
case FMT_SSHORT:
if (componentCount==1) {
int i = get16Bits(tagValueOffset);
directory.setInt(tagType, i);
} else {
int[] ints = new int[componentCount];
for (int i = 0; i<componentCount; i++)
ints[i] = get16Bits(tagValueOffset + (i * 2));
directory.setIntArray(tagType, ints);
}
break;
case FMT_SLONG:
case FMT_ULONG:
if (componentCount==1) {
int i = get32Bits(tagValueOffset);
directory.setInt(tagType, i);
} else {
int[] ints = new int[componentCount];
for (int i = 0; i<componentCount; i++)
ints[i] = get32Bits(tagValueOffset + (i * 4));
directory.setIntArray(tagType, ints);
}
break;
default:
directory.addError("Unknown format code " + formatCode + " for tag " + tagType);
}
}
private int calculateTagValueOffset(int byteCount, int dirEntryOffset, int tiffHeaderOffset)
{
if (byteCount>4) {
// If its bigger than 4 bytes, the dir entry contains an offset.
// dirEntryOffset must be passed, as some makernote implementations (e.g. FujiFilm) incorrectly use an
// offset relative to the start of the makernote itself, not the TIFF segment.
final int offsetVal = get32Bits(dirEntryOffset + 8);
if (offsetVal + byteCount>_data.length) {
// Bogus pointer offset and / or bytecount value
return -1; // signal error
}
return tiffHeaderOffset + offsetVal;
} else {
// 4 bytes or less and value is in the dir entry itself
return dirEntryOffset + 8;
}
}
/**
* Creates a String from the _data buffer starting at the specified offset,
* and ending where byte=='\0' or where length==maxLength.
*/
private String readString(int offset, int maxLength)
{
int length = 0;
while ((offset + length)<_data.length && _data[offset + length]!='\0' && length<maxLength)
length++;
return new String(_data, offset, length);
}
/**
* Determine the offset at which a given InteropArray entry begins within the specified IFD.
* @param dirStartOffset the offset at which the IFD starts
* @param entryNumber the zero-based entry number
*/
private int calculateTagOffset(int dirStartOffset, int entryNumber)
{
// add 2 bytes for the tag count
// each entry is 12 bytes, so we skip 12 * the number seen so far
return dirStartOffset + 2 + (12 * entryNumber);
}
/**
* Get a 16 bit value from file's native byte order. Between 0x0000 and 0xFFFF.
*/
private int get16Bits(int offset)
{
if (offset<0 || offset+2>_data.length)
throw new ArrayIndexOutOfBoundsException("attempt to read data outside of exif segment (index " + offset + " where max index is " + (_data.length - 1) + ")");
if (_isMotorollaByteOrder) {
// Motorola - MSB first
return (_data[offset] << 8 & 0xFF00) | (_data[offset + 1] & 0xFF);
} else {
// Intel ordering - LSB first
return (_data[offset + 1] << 8 & 0xFF00) | (_data[offset] & 0xFF);
}
}
/**
* Get a 32 bit value from file's native byte order.
*/
private int get32Bits(int offset)
{
if (offset<0 || offset+4>_data.length)
throw new ArrayIndexOutOfBoundsException("attempt to read data outside of exif segment (index " + offset + " where max index is " + (_data.length - 1) + ")");
if (_isMotorollaByteOrder) {
// Motorola - MSB first
return (_data[offset] << 24 & 0xFF000000) |
(_data[offset + 1] << 16 & 0xFF0000) |
(_data[offset + 2] << 8 & 0xFF00) |
(_data[offset + 3] & 0xFF);
} else {
// Intel ordering - LSB first
return (_data[offset + 3] << 24 & 0xFF000000) |
(_data[offset + 2] << 16 & 0xFF0000) |
(_data[offset + 1] << 8 & 0xFF00) |
(_data[offset] & 0xFF);
}
}
}