private IFDEntry readDirectoryEntry(long byteOffset) throws IOException {
MappedByteBuffer ifd = makeReadOnlyBuffer(byteOffset, 12);
char tag = ifd.getChar();
char type = ifd.getChar();
long count = unsignInt(ifd.getInt());
long value = unsignInt(ifd.getInt());
return (new IFDEntry(tag, type, count, value));
}
protected String receiveMessage() {
String message = new String();
buffer.position(0);
for (char c = buffer.getChar(); c != '\0'; c = buffer.getChar()) {
message += c;
}
return message;
}
// return byte offset of next IFD
private IFDData readIFD(long byteOffset) throws IOException {
MappedByteBuffer entries = makeReadOnlyBuffer(byteOffset, 2);
int numEntries = entries.getChar();
IFDData data = new IFDData();
for (int i = 0; i < numEntries; i++) {
IFDEntry entry = readDirectoryEntry(12 * i + 2 + byteOffset);
if (entry.tag == MM_METADATA) {
data.mdOffset = entry.value;
} else if (entry.tag == STRIP_OFFSETS) {
data.pixelOffset = entry.value;
} else if (entry.tag == STRIP_BYTE_COUNTS) {
data.bytesPerImage = entry.value;
} else if (entry.tag == BITS_PER_SAMPLE) {
if (entry.value <= 8) {
data.bytesPerPixel = 1;
} else if (entry.value <= 16) {
data.bytesPerPixel = 2;
} else {
data.bytesPerPixel = 3;
}
} else if (entry.tag == MM_METADATA_LENGTH) {
data.mdLength = entry.value;
}
}
MappedByteBuffer next = makeReadOnlyBuffer(byteOffset + 2 + 12 * numEntries, 4);
data.nextIFDAdress = unsignInt(next.getInt());
return data;
}