00001 # Software License Agreement (BSD License) 00002 # 00003 # Copyright (c) 2012, Willow Garage, Inc. 00004 # All rights reserved. 00005 # 00006 # Redistribution and use in source and binary forms, with or without 00007 # modification, are permitted provided that the following conditions 00008 # are met: 00009 # 00010 # * Redistributions of source code must retain the above copyright 00011 # notice, this list of conditions and the following disclaimer. 00012 # * Redistributions in binary form must reproduce the above 00013 # copyright notice, this list of conditions and the following 00014 # disclaimer in the documentation and/or other materials provided 00015 # with the distribution. 00016 # * Neither the name of Willow Garage, Inc. nor the names of its 00017 # contributors may be used to endorse or promote products derived 00018 # from this software without specific prior written permission. 00019 # 00020 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00021 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00022 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00023 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00024 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00025 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00026 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00027 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00028 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00029 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00030 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00031 # POSSIBILITY OF SUCH DAMAGE. 00032 00033 from PIL import Image 00034 from base64 import standard_b64encode, standard_b64decode 00035 from StringIO import StringIO 00036 from math import floor, ceil, sqrt 00037 00038 00039 def encode(string): 00040 """ PNG-compress the string in a square RBG image padded with '\n', return the b64 encoded bytes """ 00041 length = len(string) 00042 width = floor(sqrt(length/3.0)) 00043 height = ceil((length/3.0) / width) 00044 bytes_needed = int(width * height * 3) 00045 while length < bytes_needed: 00046 string += '\n' 00047 length += 1 00048 i = Image.fromstring('RGB', (int(width), int(height)), string) 00049 buff = StringIO() 00050 i.save(buff, "png") 00051 encoded = standard_b64encode(buff.getvalue()) 00052 return encoded 00053 00054 def decode(string): 00055 """ b64 decode the string, then PNG-decompress """ 00056 decoded = standard_b64decode(string) 00057 buff = StringIO(decoded) 00058 i = Image.open(buff) 00059 return i.tostring()