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 _make_codebook(self, stream):
alphabet = self._hist.keys()
ordered_alphabet = sorted(alphabet, key=self._hist.get, reverse=True)
codebook = {symbol: code for code, symbol in enumerate(ordered_alphabet)}
# Zapis książki kodów do strumienia
symbol_size = int(math.ceil(math.log(max(alphabet) or 1, 2)))
write_binary(stream, len(alphabet), num_bits=16)
write_binary(stream, symbol_size, num_bits=4)
for symbol in ordered_alphabet:
write_binary(stream, symbol, num_bits=symbol_size)
return codebook
def _encode_word(self, word, stream):
symbol = word if self._direct else self._codebook[word]
q = int(math.floor(math.log(symbol + 1, 2)))
r = symbol + 1 - math.pow(2, q)
write_unary(stream, q)
write_binary(stream, r, num_bits=q)