1import config
 2import reportlab.pdfbase.pdfdoc as pdfdoc
 3from reportlab.pdfbase.pdfdoc import _getTimeStamp, md5, bytestr, DummyDoc, PDFString, pdfdocEnc
 4import reportlab.pdfgen.canvas as canvas
 5from reportlab.pdfgen.canvas import Canvas
 6
 7class PDFInfo(pdfdoc.PDFInfo):
 8    creator = config.APP_NAME
 9    producer = config.APP_NAME
10    title = "SURVEY TITLE"
11    author = "SURVEY AUTHOR"
12    subject = "SURVEY SUBJECT"
13pdfdoc.PDFInfo = PDFInfo
14
15class PDFFile(pdfdoc.PDFFile):
16    ### just accumulates strings: keeps track of current offset
17    def __init__(self,pdfVersion=pdfdoc.PDF_VERSION_DEFAULT):
18        self.strings = []
19        self.write = self.strings.append
20        self.offset = 0
21        ### chapter 5
22        # Following Ken Lunde's advice and the PDF spec, this includes
23        # some high-order bytes.  I chose the characters for Tokyo
24        # in Shift-JIS encoding, as these cannot be mistaken for
25        # any other encoding, and we'll be able to tell if something
26        # has run our PDF files through a dodgy Unicode conversion.
27        self.add((pdfdocEnc("%%PDF-%s.%s" % pdfVersion) +
28            b'\r\n%\223\214\213\236 Survey PDF\r\n'
29            ))
30pdfdoc.PDFFile = PDFFile
31
32class PDFDocument(pdfdoc.PDFDocument):
33    def __init__(self, *args, **kwargs):
34        super().__init__(*args, **kwargs)
35        sig = self.signature = md5()
36        sig.update(b"a survey document")
37        if not self.invariant:
38            cat = _getTimeStamp()
39        else:
40            cat = 946684800.0
41        cat = ascii(cat)
42        sig.update(bytestr(cat)) # initialize with timestamp digest
43        #self.info = PDFInfo()
44        #self.info.invariant = self.invariant
45
46    def ID(self):
47        "A unique fingerprint for the file (unless in invariant mode)"
48        if self._ID:
49            return self._ID
50        digest = self.signature.digest()
51        doc = DummyDoc()
52        IDs = PDFString(digest,enc='raw').format(doc)
53        self._ID = (b'\r\n % PDF Survey -- digest\r\n ['
54                        +IDs+b' '+IDs+b']\r\n')
55        return self._ID
56canvas.pdfdoc.PDFDocument = PDFDocument