pngcompression.py
Go to the documentation of this file.
1 # Software License Agreement (BSD License)
2 #
3 # Copyright (c) 2012, Willow Garage, Inc.
4 # All rights reserved.
5 #
6 # Redistribution and use in source and binary forms, with or without
7 # modification, are permitted provided that the following conditions
8 # are met:
9 #
10 # * Redistributions of source code must retain the above copyright
11 # notice, this list of conditions and the following disclaimer.
12 # * Redistributions in binary form must reproduce the above
13 # copyright notice, this list of conditions and the following
14 # disclaimer in the documentation and/or other materials provided
15 # with the distribution.
16 # * Neither the name of Willow Garage, Inc. nor the names of its
17 # contributors may be used to endorse or promote products derived
18 # from this software without specific prior written permission.
19 #
20 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
24 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
28 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
30 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 # POSSIBILITY OF SUCH DAMAGE.
32 
33 from PIL import Image
34 from base64 import standard_b64encode, standard_b64decode
35 from rosbridge_library.util import BytesIO
36 from math import floor, ceil, sqrt
37 
38 
39 def encode(string):
40  """ PNG-compress the string in a square RBG image padded with '\n', return the b64 encoded bytes """
41  string_bytes = string.encode('utf-8')
42  length = len(string_bytes)
43  width = floor(sqrt(length/3.0))
44  height = ceil((length/3.0) / width)
45  bytes_needed = int(width * height * 3)
46  string_padded = string_bytes + (b'\n' * (bytes_needed - length))
47  i = Image.frombytes('RGB', (int(width), int(height)), string_padded)
48  buff = BytesIO()
49  i.save(buff, "png")
50  encoded = standard_b64encode(buff.getvalue()).decode()
51  return encoded
52 
53 def decode(string):
54  """ b64 decode the string, then PNG-decompress """
55  decoded = standard_b64decode(string)
56  buff = BytesIO(decoded)
57  i = Image.open(buff)
58  try:
59  return i.tostring()
60  except NotImplementedError:
61  return i.tobytes().decode('utf-8')
rosbridge_library.internal.pngcompression.encode
def encode(string)
Definition: pngcompression.py:39
rosbridge_library.util
Definition: src/rosbridge_library/util/__init__.py:1
rosbridge_library.internal.pngcompression.decode
def decode(string)
Definition: pngcompression.py:53


rosbridge_library
Author(s): Jonathan Mace
autogenerated on Tue Oct 3 2023 02:12:45