[reportlab-users] Error using ImageAndFlowables

[Lele Gaifax]

Hi all,

one of my apps builds a PDF with a slightly dynamic layout. One part uses an
ImageAndFlowables, where the size of the image as well as the flowables are
controlled by the end user.

At some point it started to crash with a "strange" traceback, and I spent a
few hours trying to understand the reason, until I found it and distilled the
little script I'm attaching below.

The problem happens when the flowables include a List *and* the image is big
enough to "include" the List (sorry, I find it difficult to explain better
than that): in other words, if the image is "little" so that on its right
there are only Paragraphs it works, but as soon its height is enough to
"reach" the List, it breaks.

The following script demonstrates the issue: it builds two documents, one with
a tiny image, the second with a slightly bigger one, that gives this
traceback (slightly edited to reduce overly long lines):

    $ python test_image.py 
    Created sample1.pdf
    Traceback (most recent call last):
      File "test_image.py", line 39, in <module>
        doc.build([ImageAndFlowables(Image('pythonpowered.gif', 30, 30), elts, imageSide='left')])
      File ".../python3.6/site-packages/reportlab/platypus/doctemplate.py", line 1213, in build
        BaseDocTemplate.build(self,flowables, canvasmaker=canvasmaker)
      File ".../python3.6/site-packages/reportlab/platypus/doctemplate.py", line 969, in build
        self.handle_flowable(flowables)
      File ".../python3.6/site-packages/reportlab/platypus/doctemplate.py", line 834, in handle_flowable
        if frame.add(f, canv, trySplit=self.allowSplitting):
      File ".../python3.6/site-packages/reportlab/platypus/frames.py", line 167, in _add
        w, h = flowable.wrap(aW, h)
      File ".../python3.6/site-packages/reportlab/platypus/flowables.py", line 1244, in wrap
        W,H0,self._C0,self._C1 = self._findSplit(canv,iW,aH)
      File ".../python3.6/site-packages/reportlab/platypus/flowables.py", line 1336, in _findSplit
        S = cdeepcopy(f).splitOn(canv,availWidth,aH)
      File ".../python3.6/site-packages/reportlab/platypus/flowables.py", line 881, in cdeepcopy
        return deepcopy(obj)
      File "/usr/lib/python3.6/copy.py", line 180, in deepcopy
        y = _reconstruct(x, memo, *rv)
      File "/usr/lib/python3.6/copy.py", line 280, in _reconstruct
        state = deepcopy(state, memo)
      File "/usr/lib/python3.6/copy.py", line 150, in deepcopy
        y = copier(x, memo)
      File "/usr/lib/python3.6/copy.py", line 240, in _deepcopy_dict
        y[deepcopy(key, memo)] = deepcopy(value, memo)
      File "/usr/lib/python3.6/copy.py", line 150, in deepcopy
        y = copier(x, memo)
      File "/usr/lib/python3.6/copy.py", line 215, in _deepcopy_list
        append(deepcopy(a, memo))
      File "/usr/lib/python3.6/copy.py", line 180, in deepcopy
        y = _reconstruct(x, memo, *rv)
      File "/usr/lib/python3.6/copy.py", line 281, in _reconstruct
        if hasattr(y, '__setstate__'):
      File ".../python3.6/site-packages/reportlab/platypus/flowables.py", line 1561, in __getattr__
        return getattr(self._flowable,a)
      File ".../python3.6/site-packages/reportlab/platypus/flowables.py", line 1557, in __getattr__
        return self.__dict__[a]
    KeyError: '_flowable'

This is the sample script:

    from reportlab.lib.pagesizes import A4
    from reportlab.platypus import ListFlowable, ListItem, Paragraph
    from reportlab.platypus import ImageAndFlowables, SimpleDocTemplate, Image
    from reportlab.lib.styles import getSampleStyleSheet

    styles = getSampleStyleSheet()

    doc = SimpleDocTemplate("sample1.pdf", pagesize=A4,
                            rightMargin=72, leftMargin=72,
                            topMargin=72, bottomMargin=18)

    elts = [Paragraph("a adfj kjh kj hkjh k", styles['Normal']),
            Paragraph("a adfj kjh kj hkjh k", styles['Normal']),
            ListFlowable([
                ListItem(Paragraph("a", styles['Normal'])),
                ListItem(Paragraph("b", styles['Normal'])),
                ListItem(Paragraph("c", styles['Normal'])),
                ListItem(Paragraph("d", styles['Normal'])),
                ListItem(Paragraph("e", styles['Normal'])),
            ], style=styles['ul'])]

    doc.build([ImageAndFlowables(Image('pythonpowered.gif', 20, 20), elts, imageSide='left')])
    print("Created sample1.pdf")

    doc = SimpleDocTemplate("sample2.pdf", pagesize=A4,
                            rightMargin=72, leftMargin=72,
                            topMargin=72, bottomMargin=18)

    elts = [Paragraph("a adfj kjh kj hkjh k", styles['Normal']),
            Paragraph("a adfj kjh kj hkjh k", styles['Normal']),
            ListFlowable([
                ListItem(Paragraph("a", styles['Normal'])),
                ListItem(Paragraph("b", styles['Normal'])),
                ListItem(Paragraph("c", styles['Normal'])),
                ListItem(Paragraph("d", styles['Normal'])),
                ListItem(Paragraph("e", styles['Normal'])),
            ], style=styles['ul'])]

    doc.build([ImageAndFlowables(Image('pythonpowered.gif', 30, 30), elts, imageSide='left')])
    print("Created sample2.pdf")

Am I abusing the ImageAndFlowables here?

Thanks in advance for any hint,
ciao, lele.
-- 
nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
lele at metapensiero.it  |                 -- Fortunato Depero, 1929.