def _process_file(input_file, output_file, apikey):
"""Shrinks input_file to output_file.
This function should be used only inside process_directory.
It takes input_file, tries to shrink it and if shrink was successful
save compressed image to output_file. Otherwise raise exception.
@return compressed: PNGResponse
"""
bytes_ = read_binary(input_file)
compressed = shrink(bytes_, apikey)
if compressed.success and compressed.bytes:
write_binary(output_file, compressed.bytes)
else:
if compressed.errno in FATAL_ERRORS:
raise StopProcessing(compressed)
elif compressed.errno == TinyPNGError.InternalServerError:
raise RetryProcessing(compressed)
return compressed
def _decode_word(self, stream):
q = read_unary(stream)
r = read_binary(stream, q)
symbol = int(math.pow(2, q) + r - 1)
return symbol if self._direct else self._codebook[symbol]
def _read_codebook(self, stream):
number_of_symbols = read_binary(stream, 16)
symbol_size = read_binary(stream, 4)
return {i: read_binary(stream, symbol_size) for i in range(number_of_symbols)}