code: def get_file_type
           type = nil
           read = []
           open_file do |file|
  
             # Check if the file is a JPEG.
             read_source(file, read, 2)
             if read[0,2] == [255, 216]
                type = JPEG
             else
                # Check if it's a PNG.
                read_source(file, read, 6)
                if read[0,8] == [137, 80, 78, 71, 13, 10, 26, 10]
                   type = PNG
                else
                   # Check if its a bitmap.
                   if read[0,2] == [66, 77]
                      size = to_integer(read[2,4])
                      type = BITMAP if size == File.size(@source)
                   end
                end
             end
  
           end
  
           type
        end
docs: This method attempts to determine the image type associated with a
   file, returning nil if it fails to make the determination.