A TIFF IFD consists of a set of TIFFField tags. Methods are * provided to query the set of tags and to obtain the raw field * array. In addition, convenience methods are provided for acquiring * the values of tags that contain a single value that fits into a * byte, int, long, float, or double. * *
Every TIFF file is made up of one or more public IFDs that are * joined in a linked list, rooted in the file header. A file may * also contain so-called private IFDs that are referenced from * tag data and do not appear in the main list. * *
This class is not a committed part of the JAI API. It may
* be removed or changed in future releases of JAI.
*
* @see TIFFField
*/
public class TIFFDirectory extends Object implements Serializable {
/** A boolean storing the endianness of the stream. */
boolean isBigEndian;
/** The number of entries in the IFD. */
int numEntries;
/** An array of TIFFFields. */
TIFFField[] fields;
/** A Hashtable indexing the fields by tag number. */
Hashtable fieldIndex = new Hashtable();
/** The offset of this IFD. */
long IFDOffset = 8;
/** The offset of the next IFD. */
long nextIFDOffset = 0;
/** The default constructor. */
TIFFDirectory() {}
private static boolean isValidEndianTag(int endian) {
return ((endian == 0x4949) || (endian == 0x4d4d));
}
/**
* Constructs a TIFFDirectory from a SeekableStream.
* The directory parameter specifies which directory to read from
* the linked list present in the stream; directory 0 is normally
* read but it is possible to store multiple images in a single
* TIFF file by maintaing multiple directories.
*
* @param stream a SeekableStream to read from.
* @param directory the index of the directory to read.
*/
public TIFFDirectory(RandomAccessFileOrArray stream, int directory)
throws IOException {
long global_save_offset = stream.getFilePointer();
long ifd_offset;
// Read the TIFF header
stream.seek(0L);
int endian = stream.readUnsignedShort();
if (!isValidEndianTag(endian)) {
throw new
IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
}
isBigEndian = (endian == 0x4d4d);
int magic = readUnsignedShort(stream);
if (magic != 42) {
throw new
IllegalArgumentException("Bad magic number, should be 42.");
}
// Get the initial ifd offset as an unsigned int (using a long)
ifd_offset = readUnsignedInt(stream);
for (int i = 0; i < directory; i++) {
if (ifd_offset == 0L) {
throw new
IllegalArgumentException("Directory number too large.");
}
stream.seek(ifd_offset);
int entries = readUnsignedShort(stream);
stream.skip(12*entries);
ifd_offset = readUnsignedInt(stream);
}
stream.seek(ifd_offset);
initialize(stream);
stream.seek(global_save_offset);
}
/**
* Constructs a TIFFDirectory by reading a SeekableStream.
* The ifd_offset parameter specifies the stream offset from which
* to begin reading; this mechanism is sometimes used to store
* private IFDs within a TIFF file that are not part of the normal
* sequence of IFDs.
*
* @param stream a SeekableStream to read from.
* @param ifd_offset the long byte offset of the directory.
* @param directory the index of the directory to read beyond the
* one at the current stream offset; zero indicates the IFD
* at the current offset.
*/
public TIFFDirectory(RandomAccessFileOrArray stream, long ifd_offset, int directory)
throws IOException {
long global_save_offset = stream.getFilePointer();
stream.seek(0L);
int endian = stream.readUnsignedShort();
if (!isValidEndianTag(endian)) {
throw new
IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
}
isBigEndian = (endian == 0x4d4d);
// Seek to the first IFD.
stream.seek(ifd_offset);
// Seek to desired IFD if necessary.
int dirNum = 0;
while(dirNum < directory) {
// Get the number of fields in the current IFD.
int numEntries = readUnsignedShort(stream);
// Skip to the next IFD offset value field.
stream.seek(ifd_offset + 12*numEntries);
// Read the offset to the next IFD beyond this one.
ifd_offset = readUnsignedInt(stream);
// Seek to the next IFD.
stream.seek(ifd_offset);
// Increment the directory.
dirNum++;
}
initialize(stream);
stream.seek(global_save_offset);
}
private static final int[] sizeOfType = {
0, // 0 = n/a
1, // 1 = byte
1, // 2 = ascii
2, // 3 = short
4, // 4 = long
8, // 5 = rational
1, // 6 = sbyte
1, // 7 = undefined
2, // 8 = sshort
4, // 9 = slong
8, // 10 = srational
4, // 11 = float
8 // 12 = double
};
private void initialize(RandomAccessFileOrArray stream) throws IOException {
long nextTagOffset = 0L;
long maxOffset = stream.length();
int i, j;
IFDOffset = stream.getFilePointer();
numEntries = readUnsignedShort(stream);
fields = new TIFFField[numEntries];
for (i = 0; (i < numEntries) && (nextTagOffset < maxOffset); i++) {
int tag = readUnsignedShort(stream);
int type = readUnsignedShort(stream);
int count = (int)(readUnsignedInt(stream));
boolean processTag = true;
// The place to return to to read the next tag
nextTagOffset = stream.getFilePointer() + 4;
try {
// If the tag data can't fit in 4 bytes, the next 4 bytes
// contain the starting offset of the data
if (count*sizeOfType[type] > 4) {
long valueOffset = readUnsignedInt(stream);
// bounds check offset for EOF
if (valueOffset < maxOffset) {
stream.seek(valueOffset);
}
else {
// bad offset pointer .. skip tag
processTag = false;
}
}
} catch (ArrayIndexOutOfBoundsException ae) {
// if the data type is unknown we should skip this TIFF Field
processTag = false;
}
if (processTag) {
fieldIndex.put(new Integer(tag), new Integer(i));
Object obj = null;
switch (type) {
case TIFFField.TIFF_BYTE:
case TIFFField.TIFF_SBYTE:
case TIFFField.TIFF_UNDEFINED:
case TIFFField.TIFF_ASCII:
byte[] bvalues = new byte[count];
stream.readFully(bvalues, 0, count);
if (type == TIFFField.TIFF_ASCII) {
// Can be multiple strings
int index = 0, prevIndex = 0;
ArrayList v = new ArrayList();
while (index < count) {
while ((index < count) && (bvalues[index++] != 0));
// When we encountered zero, means one string has ended
v.add(new String(bvalues, prevIndex,
(index - prevIndex)) );
prevIndex = index;
}
count = v.size();
String strings[] = new String[count];
for (int c = 0 ; c < count; c++) {
strings[c] = (String)v.get(c);
}
obj = strings;
} else {
obj = bvalues;
}
break;
case TIFFField.TIFF_SHORT:
char[] cvalues = new char[count];
for (j = 0; j < count; j++) {
cvalues[j] = (char)(readUnsignedShort(stream));
}
obj = cvalues;
break;
case TIFFField.TIFF_LONG:
long[] lvalues = new long[count];
for (j = 0; j < count; j++) {
lvalues[j] = readUnsignedInt(stream);
}
obj = lvalues;
break;
case TIFFField.TIFF_RATIONAL:
long[][] llvalues = new long[count][2];
for (j = 0; j < count; j++) {
llvalues[j][0] = readUnsignedInt(stream);
llvalues[j][1] = readUnsignedInt(stream);
}
obj = llvalues;
break;
case TIFFField.TIFF_SSHORT:
short[] svalues = new short[count];
for (j = 0; j < count; j++) {
svalues[j] = readShort(stream);
}
obj = svalues;
break;
case TIFFField.TIFF_SLONG:
int[] ivalues = new int[count];
for (j = 0; j < count; j++) {
ivalues[j] = readInt(stream);
}
obj = ivalues;
break;
case TIFFField.TIFF_SRATIONAL:
int[][] iivalues = new int[count][2];
for (j = 0; j < count; j++) {
iivalues[j][0] = readInt(stream);
iivalues[j][1] = readInt(stream);
}
obj = iivalues;
break;
case TIFFField.TIFF_FLOAT:
float[] fvalues = new float[count];
for (j = 0; j < count; j++) {
fvalues[j] = readFloat(stream);
}
obj = fvalues;
break;
case TIFFField.TIFF_DOUBLE:
double[] dvalues = new double[count];
for (j = 0; j < count; j++) {
dvalues[j] = readDouble(stream);
}
obj = dvalues;
break;
default:
break;
}
fields[i] = new TIFFField(tag, type, count, obj);
}
stream.seek(nextTagOffset);
}
// Read the offset of the next IFD.
nextIFDOffset = readUnsignedInt(stream);
}
/** Returns the number of directory entries. */
public int getNumEntries() {
return numEntries;
}
/**
* Returns the value of a given tag as a TIFFField,
* or null if the tag is not present.
*/
public TIFFField getField(int tag) {
Integer i = (Integer)fieldIndex.get(new Integer(tag));
if (i == null) {
return null;
} else {
return fields[i.intValue()];
}
}
/**
* Returns true if a tag appears in the directory.
*/
public boolean isTagPresent(int tag) {
return fieldIndex.containsKey(new Integer(tag));
}
/**
* Returns an ordered array of ints indicating the tag
* values.
*/
public int[] getTags() {
int[] tags = new int[fieldIndex.size()];
Enumeration e = fieldIndex.keys();
int i = 0;
while (e.hasMoreElements()) {
tags[i++] = ((Integer)e.nextElement()).intValue();
}
return tags;
}
/**
* Returns an array of TIFFFields containing all the fields
* in this directory.
*/
public TIFFField[] getFields() {
return fields;
}
/**
* Returns the value of a particular index of a given tag as a
* byte. The caller is responsible for ensuring that the tag is
* present and has type TIFFField.TIFF_SBYTE, TIFF_BYTE, or
* TIFF_UNDEFINED.
*/
public byte getFieldAsByte(int tag, int index) {
Integer i = (Integer)fieldIndex.get(new Integer(tag));
byte [] b = (fields[i.intValue()]).getAsBytes();
return b[index];
}
/**
* Returns the value of index 0 of a given tag as a
* byte. The caller is responsible for ensuring that the tag is
* present and has type TIFFField.TIFF_SBYTE, TIFF_BYTE, or
* TIFF_UNDEFINED.
*/
public byte getFieldAsByte(int tag) {
return getFieldAsByte(tag, 0);
}
/**
* Returns the value of a particular index of a given tag as a
* long. The caller is responsible for ensuring that the tag is
* present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
* TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.
*/
public long getFieldAsLong(int tag, int index) {
Integer i = (Integer)fieldIndex.get(new Integer(tag));
return (fields[i.intValue()]).getAsLong(index);
}
/**
* Returns the value of index 0 of a given tag as a
* long. The caller is responsible for ensuring that the tag is
* present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
* TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.
*/
public long getFieldAsLong(int tag) {
return getFieldAsLong(tag, 0);
}
/**
* Returns the value of a particular index of a given tag as a
* float. The caller is responsible for ensuring that the tag is
* present and has numeric type (all but TIFF_UNDEFINED and
* TIFF_ASCII).
*/
public float getFieldAsFloat(int tag, int index) {
Integer i = (Integer)fieldIndex.get(new Integer(tag));
return fields[i.intValue()].getAsFloat(index);
}
/**
* Returns the value of index 0 of a given tag as a float. The
* caller is responsible for ensuring that the tag is present and
* has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).
*/
public float getFieldAsFloat(int tag) {
return getFieldAsFloat(tag, 0);
}
/**
* Returns the value of a particular index of a given tag as a
* double. The caller is responsible for ensuring that the tag is
* present and has numeric type (all but TIFF_UNDEFINED and
* TIFF_ASCII).
*/
public double getFieldAsDouble(int tag, int index) {
Integer i = (Integer)fieldIndex.get(new Integer(tag));
return fields[i.intValue()].getAsDouble(index);
}
/**
* Returns the value of index 0 of a given tag as a double. The
* caller is responsible for ensuring that the tag is present and
* has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).
*/
public double getFieldAsDouble(int tag) {
return getFieldAsDouble(tag, 0);
}
// Methods to read primitive data types from the stream
private short readShort(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readShort();
} else {
return stream.readShortLE();
}
}
private int readUnsignedShort(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readUnsignedShort();
} else {
return stream.readUnsignedShortLE();
}
}
private int readInt(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readInt();
} else {
return stream.readIntLE();
}
}
private long readUnsignedInt(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readUnsignedInt();
} else {
return stream.readUnsignedIntLE();
}
}
private long readLong(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readLong();
} else {
return stream.readLongLE();
}
}
private float readFloat(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readFloat();
} else {
return stream.readFloatLE();
}
}
private double readDouble(RandomAccessFileOrArray stream)
throws IOException {
if (isBigEndian) {
return stream.readDouble();
} else {
return stream.readDoubleLE();
}
}
private static int readUnsignedShort(RandomAccessFileOrArray stream,
boolean isBigEndian)
throws IOException {
if (isBigEndian) {
return stream.readUnsignedShort();
} else {
return stream.readUnsignedShortLE();
}
}
private static long readUnsignedInt(RandomAccessFileOrArray stream,
boolean isBigEndian)
throws IOException {
if (isBigEndian) {
return stream.readUnsignedInt();
} else {
return stream.readUnsignedIntLE();
}
}
// Utilities
/**
* Returns the number of image directories (subimages) stored in a
* given TIFF file, represented by a SeekableStream.
*/
public static int getNumDirectories(RandomAccessFileOrArray stream)
throws IOException{
long pointer = stream.getFilePointer(); // Save stream pointer
stream.seek(0L);
int endian = stream.readUnsignedShort();
if (!isValidEndianTag(endian)) {
throw new
IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
}
boolean isBigEndian = (endian == 0x4d4d);
int magic = readUnsignedShort(stream, isBigEndian);
if (magic != 42) {
throw new
IllegalArgumentException("Bad magic number, should be 42.");
}
stream.seek(4L);
long offset = readUnsignedInt(stream, isBigEndian);
int numDirectories = 0;
while (offset != 0L) {
++numDirectories;
// EOFException means IFD was probably not properly terminated.
try {
stream.seek(offset);
int entries = readUnsignedShort(stream, isBigEndian);
stream.skip(12*entries);
offset = readUnsignedInt(stream, isBigEndian);
} catch(EOFException eof) {
numDirectories--;
break;
}
}
stream.seek(pointer); // Reset stream pointer
return numDirectories;
}
/**
* Returns a boolean indicating whether the byte order used in the
* the TIFF file is big-endian (i.e. whether the byte order is from
* the most significant to the least significant)
*/
public boolean isBigEndian() {
return isBigEndian;
}
/**
* Returns the offset of the IFD corresponding to this
* TIFFDirectory.
*/
public long getIFDOffset() {
return IFDOffset;
}
/**
* Returns the offset of the next IFD after the IFD corresponding to this
* TIFFDirectory.
*/
public long getNextIFDOffset() {
return nextIFDOffset;
}
}