def decode(file_to_decode_path, out_file_path):
"""
Decode file and write decoded data to out_file_path
:param file_to_decode_path: obviously
:param out_file_path: obviously
"""
bmp_data = read_bytearray_from_file(file_to_decode_path)
file_header = try_get_file_header(bmp_data)
bmp_data = split_bytearray(bmp_data, file_header.off_bits)[1]
msg = b'encoded'
try:
check_encoded(bmp_data, msg)
except NotEncodedError:
print("This file doesn't encoded. I can do nothing. Sorry...")
exit(3)
bmp_data = bmp_data[len(msg) * 8:]
bits_for_file_length = 32
file_length_data, bmp_data = split_bytearray(bmp_data, bits_for_file_length)
file_length = _decode_specified_bits(file_length_data, 1,
bits_for_file_length)
bit_count_data, bmp_data = split_bytearray(bmp_data, 3)
bit_count = _decode_specified_bits(bit_count_data, 1, 3) + 1
file_data = _decode(bmp_data, bit_count, file_length)
write_to(out_file_path, file_data)
def encode(bmp_file_path, file_to_encode_path, out_file_path, bit_count=1):
"""
Encode something file to BMP file and record result to out_file_path
:param bmp_file_path: BMP file
:param file_to_encode_path: File to encode
:param out_file_path: Obviously
:param bit_count: bits per byte
"""
bmp_data = read_bytearray_from_file(bmp_file_path)
file_data = read_bytearray_from_file(file_to_encode_path)
file_header = try_get_file_header(bmp_data)
bits_for_file_length = 32
header, bmp_data = split_bytearray(bmp_data, file_header.off_bits)
msg = b"encoded"
_encode(bytearray(msg), bmp_data, 1, 8)
encoded_msg, bmp_data = split_bytearray(bmp_data, len(msg) * 8)
file_length = len(file_data)
_encode((file_length,), bmp_data, 1, bits_for_file_length)
encoded_file_length, bmp_data = split_bytearray(bmp_data, bits_for_file_length)
_encode((bit_count - 1,), bmp_data, 1, 3)
encoded_bit_count, bmp_data = split_bytearray(bmp_data, 3)
try:
check_data_lost_possibility(file_data, bmp_data, bit_count)
except DataLostPossibility:
print("Your file too large for this bmp and bit count")
exit(4)
_encode(file_data, bmp_data, bit_count, 8)
header.extend(encoded_msg)
header.extend(encoded_file_length)
header.extend(encoded_bit_count)
header.extend(bmp_data)
write_to(out_file_path, header)