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from __future__ import print_function |
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import array |
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import png |
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5
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import json |
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7
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from st2actions.runners.pythonrunner import Action |
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8
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9
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__all__ = [ |
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'ImageDecoder' |
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] |
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def _get_image_array(image_path): |
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with open(image_path, 'rb') as image_fd: |
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image_reader = png.Reader(file=image_fd) |
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image_map = image_reader.read()[2] |
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return list(image_map) |
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def _get_bit_stream(message): |
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for char in message: |
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char_int = ord(char) |
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for i in range(8): |
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yield char_int >> i & 1 |
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def _assemble_bit_stream(message_array): |
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return message_array |
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def _encode_image(image, bit_stream): |
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new_image = [] |
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for byte_array in image: |
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new_byte_array = array.array('B') |
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for byte in byte_array: |
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try: |
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bit = bit_stream.next() |
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except StopIteration: |
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bit = 0 |
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new_byte = byte & int('11111110', 2) | int('0000000%s' % bit, 2) |
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new_byte_array.append(new_byte) |
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new_image.append(new_byte_array) |
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return new_image |
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def _decode_image(image): |
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return image |
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def _save_image(name, image_map): |
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image = png.from_array(image_map, mode='RGBA') |
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image.save(name) |
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def _encode(image, output_image, message): |
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for arg in [image, output_image, message]: |
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if not isinstance(arg, str): |
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raise TypeError("Argument must be string.") |
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if arg == '': |
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raise ValueError("Argument cannot be empty.") |
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image_map = _get_image_array(image) |
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bit_generator = _get_bit_stream(message) |
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encoded_array = _encode_image(image_map, bit_generator) |
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_save_image(output_image, encoded_array) |
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def _remove_null(output): |
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try: |
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output = output[:output.index(u'\u0000')] |
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except ValueError: |
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return |
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return output |
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86
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def _decode(image): |
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if not isinstance(image, str): |
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raise TypeError("Argument must be string.") |
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91
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if image == '': |
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raise ValueError("Argument cannot be empty.") |
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image_map = _get_image_array(image) |
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bit_stream = _decode_image(image_map) |
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output = _assemble_bit_stream(bit_stream) |
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return _remove_null(output) |
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100
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101
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class ImageDecoder(Action): |
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def run(self, encode, image, output_image=None, message=None): |
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if encode: |
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_encode( |
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str(image), |
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str(output_image), |
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str(message) |
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) |
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110
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return True |
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112
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elif not encode: |
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result = { |
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'message': str(_decode(str(image))) |
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} |
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116
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117
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return json.dumps(result) |
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StackStorm /
st2contrib
