Page number incorrect when using TableOfContents.render_toc

[mschoettle]

This is a follow-up to #136.

When using the new TableOfContents.render_toc and the table of contents spans more than one page, the page numbers are incorrect.

Another issue (when using page labels) is that doing "Page x of y" (via {nb}) is not possible because the last page number can then be incorrect. And when using roman numerals for the front matter it shows the total pages.

Error details

When running the below MRE, the following issues occur:

• page 2 (ToC) has an incorrect page number (57)
• all content pages are shifted by one, i.e., section 1 has page 2 instead of 3

Minimal code
Please include some minimal Python code reproducing your issue:

from fpdf import FPDF
from fpdf.outline import TableOfContents

NUMBER_SECTIONS = 56


def p(pdf, text, **kwargs):
    pdf.multi_cell(
        w=pdf.epw,
        h=pdf.font_size,
        text=text,
        new_x="LMARGIN",
        new_y="NEXT",
        **kwargs,
    )


class CustomFPDF(FPDF):
    def footer(self) -> None:
        self.set_y(-15)
        self.set_font("Helvetica", size=8)
        self.cell(w=0, h=10, text="Page %s" % self.page_no(), align="C")
        self.set_font("Helvetica", size=12)


pdf = CustomFPDF()
pdf.set_font("Helvetica", size=12)
pdf.add_page()
pdf.start_section("Test", level=0)
pdf.insert_toc_placeholder(TableOfContents().render_toc, allow_extra_pages=True)

text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."

for i in range(1, NUMBER_SECTIONS):
    if i > 1:
        pdf.add_page()
    pdf.start_section(f"Section {i}", level=1)
    p(pdf, f"Section {i}")
    p(pdf, text)

pdf.output('output.pdf')

MRE 2

When using set_page_label and get_page_label it is somewhat better:

from fpdf import FPDF
from fpdf.outline import TableOfContents

NUMBER_SECTIONS = 56


def p(pdf, text, **kwargs):
    pdf.multi_cell(
        w=pdf.epw,
        h=pdf.font_size,
        text=text,
        new_x="LMARGIN",
        new_y="NEXT",
        **kwargs,
    )


class CustomFPDF(FPDF):
    def footer(self) -> None:
        self.set_y(-15)
        self.set_font("Helvetica", size=8)
        self.cell(w=0, h=10, text="Page %s" % self.get_page_label(), align="C")
        self.set_font("Helvetica", size=12)


pdf = CustomFPDF()
pdf.set_font("Helvetica", size=12)
pdf.add_page()
pdf.set_page_label(label_style="D")
pdf.start_section("Test", level=0)
pdf.insert_toc_placeholder(TableOfContents().render_toc, allow_extra_pages=True)

text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."

for i in range(1, NUMBER_SECTIONS):
    if i > 1:
        pdf.add_page()
    pdf.start_section(f"Section {i}", level=1)
    p(pdf, f"Section {i}")
    p(pdf, text)

pdf.output('output.pdf')

Issues:

• all content pages are shifted by 1 (section 1 has page 2 instead of 3)

MRE 3

Making use of roman numerals before the actual content works with the exception of adding the total page count:

from fpdf import FPDF
from fpdf.outline import TableOfContents

NUMBER_SECTIONS = 56


def p(pdf, text, **kwargs):
    pdf.multi_cell(
        w=pdf.epw,
        h=pdf.font_size,
        text=text,
        new_x="LMARGIN",
        new_y="NEXT",
        **kwargs,
    )


class CustomFPDF(FPDF):
    def footer(self) -> None:
        self.set_y(-15)
        self.set_font("Helvetica", size=8)
        self.cell(w=0, h=10, text="Page %s of {nb}" % self.get_page_label(), align="C")
        self.set_font("Helvetica", size=12)


pdf = CustomFPDF()
pdf.set_font("Helvetica", size=12)
pdf.add_page()
pdf.set_page_label(label_style="R")
pdf.start_section("Test", level=0)
pdf.insert_toc_placeholder(TableOfContents().render_toc, allow_extra_pages=True)

text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."

pdf.set_page_label(label_style="D")

for i in range(1, NUMBER_SECTIONS):
    if i > 1:
        pdf.add_page()
    pdf.start_section(f"Section {i}", level=1)
    p(pdf, f"Section {i}")
    p(pdf, text)

pdf.output('output.pdf')

Environment
Please provide the following information:

• Operating System: Windows, Mac OSX, Linux flavour...
• Python version: 3.11.x
• fpdf2 version used: 2.8.2

[andersonhc]

The numbering issue when using allow_extra_pages is a known limitation. The only workaround I’ve found is to use page labels, so I’ve added notes about this in the documentation and docstrings.

As for your MRE3 example, the extra page appears because insert_toc_placeholder() automatically inserts a page break, and you also call add_page() before writing the first section. You can fix this by adjusting your loop so add_page() is only called after the first section:

for i in range(1, NUMBER_SECTIONS):
    if i > 1:
        pdf.add_page()
    pdf.start_section(f"Section {i}", level=1)
    p(pdf, f"Section {i}")
    p(pdf, text)

[mschoettle]

Thanks! I added this to all MREs and updated the issues.

MRE3 works with using roman numerals for the ToC and then arabic numerals for the content. The only problem with that is that the total page count (via {nb}) is incorrect in both cases.