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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...
'''
from __future__ import generators
try:
set
except NameError:
from sets import Set as set
import zlib
from pdfobjects import PdfDict, PdfName
def streamobjects(mylist):
for obj in mylist:
if isinstance(obj, PdfDict) and obj.stream is not None:
yield obj
def uncompress(mylist, warnings=set()):
flate = PdfName.FlateDecode
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)
print msg
else:
obj.stream = zlib.decompress(obj.stream)
obj.Filter = None
def compress(mylist):
flate = PdfName.FlateDecode
for obj in streamobjects(mylist):
ftype = obj.Filter
if ftype is not None:
continue
oldstr = obj.stream
newstr = zlib.compress(oldstr)
if len(newstr) < len(oldstr) + 30:
obj.stream = newstr
obj.Filter = flate
obj.DecodeParms = None
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