python-2.7 - Python ReportLab - X of Y ページ番号付きのクリック可能な目次

Question

ReportLab 2.7、Python 2.7 を使用:

目次 (toc) でクリック可能なブックマークを使用して PDF を作成するか、「x of y」ページ番号を使用して PDF を作成できますが、両方を実行しようとするとブックマークページ (キー) が壊れているように見えます。

コード例:

class MyDocTemplate(BaseDocTemplate):  
    def __init__(self, filename, **kw):
        self.allowSplitting = 0
        BaseDocTemplate.__init__(self, filename, **kw)
        template = PageTemplate('normal', [Frame(2.5*cm, 2.5*cm, 15*cm, 25*cm)]) #, id='F1'
        self.addPageTemplates(template)

def afterFlowable(self, flowable):
    if isinstance(flowable, Paragraph):
        txt = flowable.getPlainText()
        style = flowable.style.name
        if style == 'Heading1':
            key = 'h1-%s' % self.seq.nextf('heading1')
            self.canv.bookmarkPage(key)                
            self.notify('TOCEntry', (0, txt, self.page))
        elif style == 'Heading2':
            key = 'h2-%s' % self.seq.nextf('heading2')
            print key
            self.canv.bookmarkPage(key)
            self.notify('TOCEntry', (1, txt, self.page, key))

class NumberedCanvas(canvas.Canvas):
    def __init__(self, *args, **kwargs):
        canvas.Canvas.__init__(self, *args, **kwargs)
        self._saved_page_states = []

    def showPage(self):
        self._saved_page_states.append(dict(self.__dict__))
        self._startPage()

    def save(self):
        """add page info to each page (page x of y)"""
        num_pages = len(self._saved_page_states)
        for state in self._saved_page_states:
            self.__dict__.update(state)
            self.draw_page_number(num_pages)
            canvas.Canvas.showPage(self)
        canvas.Canvas.save(self)

    def draw_page_number(self, page_count):
        self.setFont('Times-Bold',14)
        self.drawRightString(7.6*inch,.5*inch,
        "Page %d of %d" % (self._pageNumber, page_count))

    h1 = PS(name = 'Heading1',
    fontSize = 14,
    leading = 16)
    h2 = PS(name = 'Heading2',
    fontSize = 12,
    leading = 14,
    leftIndent = 25)

    #Build story.
    story = []
    toc = TableOfContents()

    #For conciseness, using the same styles for headings and TOC entries
    toc.levelStyles = [h1, h2]
    story.append(toc)
    story.append(PageBreak())
    story.append(Paragraph('First heading', h1))
    story.append(Paragraph('Text in first heading', PS('body')))
    story.append(Paragraph('First sub heading', h2))
    story.append(Paragraph('Text in first sub heading', PS('body')))
    story.append(PageBreak())
    story.append(Paragraph('Second sub heading', h2))
    story.append(Paragraph('Text in second sub heading', PS('body')))
    story.append(Paragraph('Last heading', h1))
    doc = MyDocTemplate("mypdf.pdf")
    doc.multiBuild(story, canvasmaker=NumberedCanvas)

どんなコメントでも大歓迎です。