fpdf2.3.0 Unbreakable! and PDF quines

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Unbreakable movie poster

Today, I am happy to announce version 2.3.0 of fpdf2, code name: Unbreakable!

https://github.com/pyfpdf/fpdf2/ Pypi latest version Doc: https://pyfpdf.github.io/fpdf2/

Why Unbreakable?

  • As a tribute to M. Night Shyamalan movie
  • Because using fpdf2, your Python code can never break!
    ...
    Just kidding, I would be a fool to think the library contains zero bug 😅
  • Because this release introduces a new unbreakable() method, ensuring that inside this context manager, no page break will happen:
with pdf.unbreakable() as pdf:
    for row in data:
        for datum in row:
            pdf.cell(col_width, line_height, datum", border=1)
        pdf.ln(line_height)
pdf.ln(line_height * 2)

Check the documentation page on Page breaks for more details.

This release also brings a few other things:

  • bug fixes for the FPDF.alias_nb_pages & FPDF.set_font methods
  • new FPDF.epw & FPDF.eph @property methods, providing the effective page width & height
  • several new documentation pages: feeding HTML, creating links, tables, text styling...

Check the CHANGELOG.md for more details!

PDF quines

Since I have started working on fpdf2, I have this idea in the back of my mind: could be possible to write a PDF quine?

The term "quine" may not be well known, so I'll quote the Wikipedia page on the subject:

A quine is a computer program which produces a copy of its own source code as its only output.

Example with Python 3.8+:

exec(s:='print("exec(s:=%r)"%s)')

Or with bash:

a(){ echo $2 \\$1 $1 $2 $1 ;};a \' ' a(){ echo $2 \\$1 $1 $2 $1 ;};a '

There is also the amazing quinesnake, a quine in C language, that is also a video game !

Unbreakable movie poster

No, could it be possible to build a PDF that displays its own source code?

I have to admit that I haven't been able to craft one myself so far...

As a starting point, there is a really minimal PDF source code:

%PDF-1.3
%âãÏÓ
1 0 obj<</Pages 2 0 R>>endobj
2 0 obj<</Count 1 /Kids [3 0 R] /Type /Pages>>endobj
3 0 obj<</Contents 4 0 R /MediaBox [0 0 300 200] /Resources <</Font <</F <</BaseFont /Courier /Encoding /WinAnsiEncoding>>>>>> /Type /Page>>endobj
4 0 obj<</Length 50>>stream
BT /F 8 Tf 0 10 TD <25e2e3cfd3> Tj (%PDF-1.3) ' ETendstream endobj
xref
0 5
0000000000 65535 f
0000000014 00000 n
0000000045 00000 n
0000000097 00000 n
0000000244 00000 n
trailer<</Root 1 0 R /Size 5>>
startxref
340
%%EOF

If you paste this in a text file, and rename it with a .pdf extension, you should be able to open it with a PDF viewer, and the two first lines of this code snippet should be displayed.

So, as I was a bit stuck to go further, I built this PDF that displays its own source code as Python:

PDF

What do you think, is it cheating? 😜

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