Duplicating PDF with PyPDF2 gives blank pages

Question

I'm using PyPDF2 to alter a PDF document (adding bookmarks). So I need to read in the entire source PDF, and write it out, keeping as much of the data intact as possible. Merely writing each page into a new PDF object may not be sufficient to preserve document metadata.

PdfFileWriter() does have a number of methods for copying an entire file: cloneDocumentFromReader, appendPagesFromReader and cloneReaderDocumentRoot. However, they all have problems.

If I use cloneDocumentFromReader or appendPagesFromReader, I get a valid PDF file, with the correct number of pages, but all pages are blank.

If I use cloneReaderDocumentRoot, I get a minimal valid PDF file, but with no pages or data.

This has been asked before, but with no successful answers. Other questions have asked about Blank pages in PyPDF2, but I can't apply the answer given.

Here's my code:

def bookmark(incomingFile):
    reader = PdfFileReader(incomingFile)
    writer = PdfFileWriter()

    writer.appendPagesFromReader(reader)
    #writer.cloneDocumentFromReader(reader)
    my_table_of_contents = [
            ('Page 1', 0), 
            ('Page 2', 1),
            ('Page 3', 2)
            ]
    # writer.addBookmark(title, pagenum, parent=None, color=None, bold=False, italic=False, fit='/Fit')
    for title, pagenum in my_table_of_contents:
        writer.addBookmark(title, pagenum, parent=None)

    writer.setPageMode("/UseOutlines")

    with open(incomingFile, "wb") as fp:
        writer.write(fp)

I tend to get errors when PyPDF2 can't add a bookmark to the PdfFileWriter object, because it doesn't have any pages, or similar.

Answer 1

I also wrestled with this a lot, finally found that PyPDF2 has this issue. Basically I copied this answer's code into C:\ProgramData\Anaconda3\lib\site-packages\PyPDF2\pdf.py (this will depend on your distribution) around line 382 for the cloneDocumentFromReader function.

After that I was able to append the reader pages to the writer with writer.cloneDocumentFromReader(pdf) and, in my case, to update PDF Metadata (Subject, Keywords, etc.).

Hope this helps you

    '''
    Create a copy (clone) of a document from a PDF file reader

    :param reader: PDF file reader instance from which the clone
        should be created.
    :callback after_page_append (function): Callback function that is invoked after
        each page is appended to the writer. Signature includes a reference to the
        appended page (delegates to appendPagesFromReader). Callback signature:

        :param writer_pageref (PDF page reference): Reference to the page just
            appended to the document.
    '''
    debug = False
    if debug:
        print("Number of Objects: %d" % len(self._objects))
        for obj in self._objects:
            print("\tObject is %r" % obj)
            if hasattr(obj, "indirectRef") and obj.indirectRef != None:
                print("\t\tObject's reference is %r %r, at PDF %r" % (obj.indirectRef.idnum, obj.indirectRef.generation, obj.indirectRef.pdf))

    # Variables used for after cloning the root to
    # improve pre- and post- cloning experience

    mustAddTogether = False
    newInfoRef = self._info
    oldPagesRef = self._pages
    oldPages = self.getObject(self._pages)

    # If there have already been any number of pages added

    if oldPages[NameObject("/Count")] > 0:

        # Keep them

        mustAddTogether = True
    else:

        # Through the page object out

        if oldPages in self._objects:
            newInfoRef = self._pages
            self._objects.remove(oldPages)

    # Clone the reader's root document

    self.cloneReaderDocumentRoot(reader)
    if not self._root:
        self._root = self._addObject(self._root_object)

    # Sweep for all indirect references

    externalReferenceMap = {}
    self.stack = []
    newRootRef = self._sweepIndirectReferences(externalReferenceMap, self._root)

    # Delete the stack to reset

    del self.stack

    #Clean-Up Time!!!

    # Get the new root of the PDF

    realRoot = self.getObject(newRootRef)

    # Get the new pages tree root and its ID Number

    tmpPages = realRoot[NameObject("/Pages")]
    newIdNumForPages = 1 + self._objects.index(tmpPages)

    # Make an IndirectObject just for the new Pages

    self._pages = IndirectObject(newIdNumForPages, 0, self)

    # If there are any pages to add back in

    if mustAddTogether:

        # Set the new page's root's parent to the old
        # page's root's reference

        tmpPages[NameObject("/Parent")] = oldPagesRef

        # Add the reference to the new page's root in
        # the old page's kids array

        newPagesRef = self._pages
        oldPages[NameObject("/Kids")].append(newPagesRef)

        # Set all references to the root of the old/new
        # page's root

        self._pages = oldPagesRef
        realRoot[NameObject("/Pages")] = oldPagesRef

        # Update the count attribute of the page's root

        oldPages[NameObject("/Count")] = NumberObject(oldPages[NameObject("/Count")] + tmpPages[NameObject("/Count")])

    else:

        # Bump up the info's reference b/c the old
        # page's tree was bumped off

        self._info = newInfoRef