python - PyPDF2:复制 PDF 会产生空白页

Question

我正在使用 PyPDF2更改 PDF 文档(添加书签)。所以我需要读入整个源 PDF 并将其写出来，尽可能多地保持数据完整。仅将每一页写入新的 PDF 对象可能不足以保留文档元数据。
PdfFileWriter()确实有许多复制整个文件的方法:cloneDocumentFromReader , appendPagesFromReader和 cloneReaderDocumentRoot .然而，他们都有问题。

如果我使用 cloneDocumentFromReader或 appendPagesFromReader , 我得到一个有效的 PDF 文件，页数正确，但所有页面都是空白的。

如果我使用 cloneReaderDocumentRoot , 我得到一个最小的有效 PDF 文件，但没有页面或数据。

This has been asked before ，但没有成功的答案。
其他问题已询问 Blank pages in PyPDF2 ，但我不能应用给出的答案。

这是我的代码:

def bookmark(incomingFile):
    fileObj = open(incomingFile, 'rb')
    output = PdfFileWriter()
    input = PdfFileReader(fileObj)

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

    output.setPageMode("/UseOutlines")

    outputStream = open(incomingFile, "wb")
    output.write(outputStream)
    outputStream.close()
    fileObj.close()

当 PyPDF2 无法向 PdfFileWriter 对象添加书签时，我往往会出错，因为它没有任何页面或类似内容。

Answer 1

我也纠结了很久，终于发现PyPDF2有这个issue .
基本上我复制了this answer's编码到C:\ProgramData\Anaconda3\lib\site-packages\PyPDF2\pdf.py (这将取决于您的发行版)在 cloneDocumentFromReader 的第 382 行附近功能。

之后，我能够附加 reader页到 writer与 writer.cloneDocumentFromReader(pdf)并且，就我而言，更新 PDF 元数据(主题、关键字等)。

希望这对你有帮助

    '''
    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