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# A part of pdfrw (pdfrw.googlecode.com)
# Copyright (C) 2006-2009 Patrick Maupin, Austin, Texas
# MIT license -- See LICENSE.txt for details
'''
Currently, this sad little file only knows how to decompress
using the flate (zlib) algorithm. Maybe more later, but it's
not a priority for me...
'''
import zlib
from pdfrw.objects import PdfDict, PdfName
from pdfrw.errors import log
def streamobjects(mylist, isinstance=isinstance, PdfDict=PdfDict):
for obj in mylist:
if isinstance(obj, PdfDict) and obj.stream is not None:
yield obj
def uncompress(mylist, warnings=set(), flate = PdfName.FlateDecode,
decompress=zlib.decompressobj, isinstance=isinstance, list=list, len=len):
ok = True
for obj in streamobjects(mylist):
ftype = obj.Filter
if ftype is None:
continue
if isinstance(ftype, list) and len(ftype) == 1:
# todo: multiple filters
ftype = ftype[0]
parms = obj.DecodeParms
if ftype != flate or parms is not None:
msg = 'Not decompressing: cannot use filter %s with parameters %s' % (repr(ftype), repr(parms))
if msg not in warnings:
warnings.add(msg)
log.warning(msg)
ok = False
else:
dco = decompress()
error = None
try:
data = dco.decompress(obj.stream)
except Exception, s:
error = str(s)
if error is None:
assert not dco.unconsumed_tail
if dco.unused_data.strip():
error = 'Unconsumed compression data: %s' % repr(dco.unused_data[:20])
if error is None:
obj.Filter = None
obj.stream = data
else:
log.error('%s %s' % (error, repr(obj.indirect)))
return ok
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