# vim: sw=4:expandtab:foldmethod=marker
#
# Copyright (c) 2006, Mathieu Fenniak
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""
Implementation of stream filters for PDF.
"""
__author__ = "Mathieu Fenniak"
__author_email__ = "biziqe@mathieu.fenniak.net"
from utils import PdfReadError
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
try:
import zlib
def decompress(data):
return zlib.decompress(data)
def compress(data):
return zlib.compress(data)
except ImportError:
# Unable to import zlib. Attempt to use the System.IO.Compression
# library from the .NET framework. (IronPython only)
import System
from System import IO,Collections,Array
def _string_to_bytearr(buf):
retval = Array.CreateInstance(System.Byte, len(buf))
for i in range(len(buf)):
retval[i] = ord(buf[i])
return retval
def _bytearr_to_string(bytes):
retval = ""
for i in range(bytes.Length):
retval += chr(bytes[i])
return retval
def _read_bytes(stream):
ms = IO.MemoryStream()
buf = Array.CreateInstance(System.Byte, 2048)
while True:
bytes = stream.Read(buf, 0, buf.Length)
if bytes == 0:
break
else:
ms.Write(buf, 0, bytes)
retval = ms.ToArray()
ms.Close()
return retval
def decompress(data):
bytes = _string_to_bytearr(data)
ms = IO.MemoryStream()
ms.Write(bytes, 0, bytes.Length)
ms.Position = 0 # fseek 0
gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Decompress)
bytes = _read_bytes(gz)
retval = _bytearr_to_string(bytes)
gz.Close()
return retval
def compress(data):
bytes = _string_to_bytearr(data)
ms = IO.MemoryStream()
gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Compress, True)
gz.Write(bytes, 0, bytes.Length)
gz.Close()
ms.Position = 0 # fseek 0
bytes = ms.ToArray()
retval = _bytearr_to_string(bytes)
ms.Close()
return retval
class FlateDecode(object):
def decode(data, decodeParms):
data = decompress(data)
predictor = 1
if decodeParms:
predictor = decodeParms.get("/Predictor", 1)
# predictor 1 == no predictor
if predictor != 1:
columns = decodeParms["/Columns"]
# PNG prediction:
if predictor >= 10 and predictor <= 15:
output = StringIO()
# PNG prediction can vary from row to row
rowlength = columns + 1
assert len(data) % rowlength == 0
prev_rowdata = (0,) * rowlength
for row in xrange(len(data) / rowlength):
rowdata = [ord(x) for x in data[(row*rowlength):((row+1)*rowlength)]]
filterByte = rowdata[0]
if filterByte == 0:
pass
elif filterByte == 1:
for i in range(2, rowlength):
rowdata[i] = (rowdata[i] + rowdata[i-1]) % 256
elif filterByte == 2:
for i in range(1, rowlength):
rowdata[i] = (rowdata[i] + prev_rowdata[i]) % 256
else:
# unsupported PNG filter
raise PdfReadError("Unsupported PNG filter %r" % filterByte)
prev_rowdata = rowdata
output.write(''.join([chr(x) for x in rowdata[1:]]))
data = output.getvalue()
else:
# unsupported predictor
raise PdfReadError("Unsupported flatedecode predictor %r" % predictor)
return data
decode = staticmethod(decode)
def encode(data):
return compress(data)
encode = staticmethod(encode)
class ASCIIHexDecode(object):
def decode(data, decodeParms=None):
retval = ""
char = ""
x = 0
while True:
c = data[x]
if c == ">":
break
elif c.isspace():
x += 1
continue
char += c
if len(char) == 2:
retval += chr(int(char, base=16))
char = ""
x += 1
assert char == ""
return retval
decode = staticmethod(decode)
class ASCII85Decode(object):
def decode(data, decodeParms=None):
retval = ""
group = []
x = 0
hitEod = False
# remove all whitespace from data
data = [y for y in data if not (y in ' \n\r\t')]
while not hitEod:
c = data[x]
if len(retval) == 0 and c == "<" and data[x+1] == "~":
x += 2
continue
#elif c.isspace():
# x += 1
# continue
elif c == 'z':
assert len(group) == 0
retval += '\x00\x00\x00\x00'
continue
elif c == "~" and data[x+1] == ">":
if len(group) != 0:
# cannot have a final group of just 1 char
assert len(group) > 1
cnt = len(group) - 1
group += [ 85, 85, 85 ]
hitEod = cnt
else:
break
else:
c = ord(c) - 33
assert c >= 0 and c < 85
group += [ c ]
if len(group) >= 5:
b = group[0] * (85**4) + \
group[1] * (85**3) + \
group[2] * (85**2) + \
group[3] * 85 + \
group[4]
assert b < (2**32 - 1)
c4 = chr((b >> 0) % 256)
c3 = chr((b >> 8) % 256)
c2 = chr((b >> 16) % 256)
c1 = chr(b >> 24)
retval += (c1 + c2 + c3 + c4)
if hitEod:
retval = retval[:-4+hitEod]
group = []
x += 1
return retval
decode = staticmethod(decode)
def decodeStreamData(stream):
from generic import NameObject
filters = stream.get("/Filter", ())
if len(filters) and not isinstance(filters[0], NameObject):
# we have a single filter instance
filters = (filters,)
data = stream._data
for filterType in filters:
if filterType == "/FlateDecode":
data = FlateDecode.decode(data, stream.get("/DecodeParms"))
elif filterType == "/ASCIIHexDecode":
data = ASCIIHexDecode.decode(data)
elif filterType == "/ASCII85Decode":
data = ASCII85Decode.decode(data)
elif filterType == "/Crypt":
decodeParams = stream.get("/DecodeParams", {})
if "/Name" not in decodeParams and "/Type" not in decodeParams:
pass
else:
raise NotImplementedError("/Crypt filter with /Name or /Type not supported yet")
else:
# unsupported filter
raise NotImplementedError("unsupported filter %s" % filterType)
return data
if __name__ == "__main__":
assert "abc" == ASCIIHexDecode.decode('61\n626\n3>')
ascii85Test = """
<~9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,
O<DJ+*.@<*K0@<6L(Df-\\0Ec5e;DffZ(EZee.Bl.9pF"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY
i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa
l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G
>uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c~>
"""
ascii85_originalText="Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure."
assert ASCII85Decode.decode(ascii85Test) == ascii85_originalText
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