Returns the number of bytes that are necessary from the compressed output stream to decode all the symbols that have been coded this far. The number of returned bytes does not include anything coded previous to the last time the 'terminate()' or 'reset()' methods where called.

       <p>The values returned by this method are then to be used in finishing
       the length calculation with the 'finishLengthCalculation()' method,
       after compensation of the offset in the number of bytes due to previous
       terminated segments.</p><p>This method should not be called if the current coding pass is to be
       terminated. The 'terminate()' method should be called instead.</p><p>The calculation is done based on the type of length calculation
       specified at the constructor.</p>