Reportlab / platypus bug?

[Les]

Unfortunately, the reportlab-users mailing list is unavailable (I cannot
subscribe). There is paid support but since I already have a workaround, I
won't pay for this. I think this is a documentation error of the reportlab
package. (They do not mention that stories cannot be reused.)

I think we can say that my original problem is solved, because I have a
workaround that always works.

Schachner, Joseph <Joseph.Schachner at teledyne.com> ezt írta (időpont: 2022.
márc. 14., H 19:09):

> I realize this is Python code, but I doubt that the question is a Python
> question.  I have used Python +numpy, scipy, matplotlib for years.   I have
> not used reportlab and have no idea about the reported problem except that
> I will be very surprised if it turns out to be a Python language issue.
>  Is there possibly a better place to ask this question?
>
>
> Teledyne Confidential; Commercially Sensitive Business Data
>
> -----Original Message-----
> From: Les <nagylzs at gmail.com>
> Sent: Sunday, March 13, 2022 4:56 PM
> To: python-list at python.org
> Subject: Reportlab / platypus bug?
>
>   Hello,
>
> I have found an error, and I created a minimal working example. The
> minimal working example starts with the very first example from Platypus
> user guide:
>
> from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer from
> reportlab.lib.styles import getSampleStyleSheet from
> reportlab.lib.pagesizes import A4 from reportlab.lib.units import inch
>
> PAGE_HEIGHT = A4[1]
> PAGE_WIDTH = A4[0]
> styles = getSampleStyleSheet()
>
> Title = "Hello world"
> pageinfo = "platypus example"
>
>
> def myFirstPage(canvas, doc):
>     canvas.saveState()
>     canvas.setFont('Times-Bold', 16)
>     canvas.drawCentredString(PAGE_WIDTH / 2.0, PAGE_HEIGHT - 108, Title)
>     canvas.setFont('Times-Roman', 9)
>     canvas.drawString(inch, 0.75 * inch, "First Page / %s" % pageinfo)
>     canvas.restoreState()
>
>
> def myLaterPages(canvas, doc):
>     canvas.saveState()
>     canvas.setFont('Times-Roman', 9)
>     canvas.drawString(inch, 0.75 * inch, "Page %d %s" % (doc.page,
> pageinfo))
>     canvas.restoreState()
>
>
> def go():
>     Story = [Spacer(1, 2 * inch)]
>     style = styles["Normal"]
>     for i in range(100):
>         bogustext = ("This is Paragraph number %s. " % i) * 20
>         p = Paragraph(bogustext, style)
>         Story.append(p)
>         Story.append(Spacer(1, 0.2 * inch))
>     doc = SimpleDocTemplate("phello.pdf")
>     doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages)
>
>
> go()
>
>
> If I change it to this (e.g. generate two identical files):
>
> doc = SimpleDocTemplate("phello.pdf")
> doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages) doc =
> SimpleDocTemplate("phello2.pdf") doc.build(Story, onFirstPage=myFirstPage,
> onLaterPages=myLaterPages)
>
>
> then it builds phello.pdf correctly, but builds a totally empty phello2.pdf
> (960 bytes, a single white empty page).
>
> It is hard to explain as it is, but something even more interesting
> happens if you try to make them totally independent, and create a copy of
> the story as well:
>
> import copy
> doc = SimpleDocTemplate("phello.pdf")
> doc.build(copy.copy(Story), onFirstPage=myFirstPage,
> onLaterPages=myLaterPages) doc = SimpleDocTemplate("phello2.pdf")
> doc.build(copy.copy(Story), onFirstPage=myFirstPage,
> onLaterPages=myLaterPages)
>
>
> This will render phello.pdf correctly, and it will throw this error when
> rendering phello2.pdf:
>
> Traceback (most recent call last):
>   File "C:\Projects\test\test2.py", line 48, in <module>
>     go()
>   File "C:\Projects\test\test2.py", line 45, in go
>     doc.build(copy.copy(Story), onFirstPage=myFirstPage,
> onLaterPages=myLaterPages)
>   File
>
> "C:\Users\nagyl\.virtualenvs\test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py",
> line 1314, in build
>     BaseDocTemplate.build(self,flowables, canvasmaker=canvasmaker)
>   File "C:\Users\nagyl\.virtualenvs\
> test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py", line
> 1079, in build
>     self.handle_flowable(flowables)
>   File "C:\Users\nagyl\.virtualenvs\
> test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py", line
> 958, in handle_flowable
>     raise LayoutError(ident)
> reportlab.platypus.doctemplate.LayoutError: Flowable <Paragraph at
> 0x148e102cb80 frame=normal>This is Paragraph number 6. This is Paragraph
> number 6. This(439.27559055118115 x 72) too large on page 1 in frame
> 'normal'(439.27559055118115 x 685.8897637795277) of template 'First'
>
> And finally, here is the "solution" that solves all problems:
>
>
> def go():
>     def create_story():
>         Story = [Spacer(1, 2 * inch)]
>         style = styles["Normal"]
>         for i in range(100):
>             bogustext = ("This is Paragraph number %s. " % i) * 20
>             p = Paragraph(bogustext, style)
>             Story.append(p)
>             Story.append(Spacer(1, 0.2 * inch))
>         return Story
>
>     doc = SimpleDocTemplate("phello.pdf")
>     doc.build(create_story(), onFirstPage=myFirstPage,
> onLaterPages=myLaterPages)
>     doc = SimpleDocTemplate("phello2.pdf")
>     doc.build(create_story(), onFirstPage=myFirstPage,
> onLaterPages=myLaterPages)
>
>
> This does not throw an error, and it renders both files correctly. But I
> do not see why this last version works, and the previous one (that uses
> copy.copy) does not.
>
> I was looking for an explanation in the user guide. I was looking for a
> note, telling me that a story can be used for document generation only
> once. But there is no such thing in the docs. Or maybe I just did not find
> it. Can somebody please explain what is happening here?
>
> Environment details: Python 3.10.1 amd64 on Windows, reportlab 3.6.6
>
> Thanks,
>
>     Laszlo
> --
> https://mail.python.org/mailman/listinfo/python-list
>