/*
* Reads and returns an array of bytes from the file.
*
*/
public byte[] readBytes(TiffIFDEntry entry) throws IOException {
byte[] bytes = new byte[(int) entry.count];
ByteBuffer buff = ByteBuffer.wrap(bytes);
this.theChannel.position(entry.asOffset());
this.theChannel.read(buff);
return bytes;
}
/*
* Reads a ColorMap.
*
*/
public byte[][] readColorMap(TiffIFDEntry colorMapEntry) throws IOException {
if (null == colorMapEntry) {
String message = Logging.getMessage("GeotiffReader.MissingColormap");
Logging.logger().severe(message);
throw new IOException(message);
}
// NOTE: TIFF gives total number of cmap values, which is 3 times the size of cmap table...
// CLUT is composed of shorts, but we'll read as bytes (thus, the factor of 2)...
int numEntries = (int) colorMapEntry.count / 3;
byte[][] tmp = new byte[3][numEntries * 2];
this.theChannel.position(colorMapEntry.asLong());
// Unroll the loop; the TIFF spec says "...3 is the number of the counting, and the counting
// shall be 3..."
// TIFF spec also says that all red values precede all green, which precede all blue.
ByteBuffer buff = ByteBuffer.wrap(tmp[0]);
this.theChannel.read(buff);
buff = ByteBuffer.wrap(tmp[1]);
this.theChannel.read(buff);
buff = ByteBuffer.wrap(tmp[2]);
this.theChannel.read(buff);
// TIFF gives a ColorMap composed of unsigned shorts. Java's IndexedColorModel wants unsigned
// bytes.
// Something's got to give somewhere...we'll do our best.
byte[][] cmap = new byte[3][numEntries];
for (int i = 0; i < 3; i++) {
buff = ByteBuffer.wrap(tmp[i]);
buff.order(this.getByteOrder());
for (int j = 0; j < numEntries; j++) {
cmap[i][j] = (byte) (0x00ff & buff.getShort());
}
}
return cmap;
}
