Method decode

pattern/web/pdf/pdftypes.py:196–252

(self)

        return [ filters ]

    def decode(self):
        assert self.data is None and self.rawdata != None
        data = self.rawdata
        if self.decipher:
            # Handle encryption
            data = self.decipher(self.objid, self.genno, data)
        filters = self.get_filters()
        if not filters:
            self.data = data
            self.rawdata = None
            return
        for f in filters:
            if f in LITERALS_FLATE_DECODE:
                # will get errors if the document is encrypted.
                try:
                    data = zlib.decompress(data)
                except zlib.error, e:
                    if STRICT:
                        raise PDFException('Invalid zlib bytes: %r, %r' % (e, data))
                    data = ''
            elif f in LITERALS_LZW_DECODE:
                data = lzwdecode(data)
            elif f in LITERALS_ASCII85_DECODE:
                data = ascii85decode(data)
            elif f in LITERALS_ASCIIHEX_DECODE:
                data = asciihexdecode(data)
            elif f in LITERALS_RUNLENGTH_DECODE:
                data = rldecode(data)
            elif f in LITERALS_CCITTFAX_DECODE:
                #data = ccittfaxdecode(data)
                raise PDFNotImplementedError('Unsupported filter: %r' % f)
            elif f == LITERAL_CRYPT:
                # not yet..
                raise PDFNotImplementedError('/Crypt filter is unsupported')
            else:
                raise PDFNotImplementedError('Unsupported filter: %r' % f)
            # apply predictors
            params = self.get_any(('DP', 'DecodeParms', 'FDecodeParms'), {})
            if 'Predictor' in params and 'Columns' in params:
                pred = int_value(params['Predictor'])
                columns = int_value(params['Columns'])
                if pred:
                    if pred != 12:
                        raise PDFNotImplementedError('Unsupported predictor: %r' % pred)
                    buf = ''
                    ent0 = '\x00' * columns
                    for i in xrange(0, len(data), columns+1):
                        pred = data[i]
                        ent1 = data[i+1:i+1+columns]
                        if pred == '\x02':
                            ent1 = ''.join( chr((ord(a)+ord(b)) & 255) for (a,b) in zip(ent0,ent1) )
                        buf += ent1
                        ent0 = ent1
                    data = buf
        self.data = data
        self.rawdata = None
        return