BUG: Scale PDF annotations

[joshhendo]

Fixes #1386

PDF annotations - for example hyperlinks and comments - aren't properly scaled when using the scale function.

I tried to follow a similar pattern to the code just below my change which scales the Viewport.

As a test, the input PDF is as follows:

In this screenshot, I am clicking on the link and Adobe Acrobat shows it as a black box. This is in the position I expect.

When scaled to 0.9 without this fix, the following occurs:

The clickable area for the link has changed, as well as the comment.

The PDF used to test was:
test_input.pdf

The PDF scaled to 0.9 before the fix:
test_output_before.pdf

The PDF scaled to 0.9 after the fix:
test_output_after.pdf

[joshhendo]

I'm not sure why the CI is failing indicating that the annotations aren't iterable - it seems to be when I run it and I based the code on the docs here: https://pypdf2.readthedocs.io/en/latest/user/reading-pdf-annotations.html?highlight=annotations

Perhaps it's not guaranteed to be iterable and there needs to be some form of type guard before attempting to iterate it.

[codecov]

Codecov Report

Base: 93.97% // Head: 93.93% // Decreases project coverage by -0.04% ⚠️

Coverage data is based on head (2a060d9) compared to base (b1938aa).
Patch coverage: 76.92% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1479      +/-   ##
==========================================
- Coverage   93.97%   93.93%   -0.05%     
==========================================
  Files          30       30              
  Lines        5446     5459      +13     
  Branches     1039     1044       +5     
==========================================
+ Hits         5118     5128      +10     
  Misses        198      198              
- Partials      130      133       +3     

Impacted Files	Coverage Δ
PyPDF2/_page.py	91.92% <76.92%> (-0.30%)	⬇️

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[MartinThoma]

@joshhendo Thank you for taking care of it 🙏 I'll release it to PyPI today :-)

If you want, I can add you to the list of contributors: https://pypdf2.readthedocs.io/en/latest/meta/CONTRIBUTORS.html :-)

[joshhendo]

Thanks @MartinThoma ! And for fixing the mypy issue - I was on the right path thinking that narrowing/a type guard was needed. I have never used mypy before so I had been trying to get it working locally for me to work on.

[joshhendo]

If you want, I can add you to the list of contributors: https://pypdf2.readthedocs.io/en/latest/meta/CONTRIBUTORS.html :-)

That would be great!

[pubpub-zz]

@joshhendo / @MartinThoma
This PR only fixes scaling but not the other transformations. Actually, the annotations reposition should be applied within the add_transformation function.
example with a rotation of -10deg

@joshhendo, are you OK to upgrade your code change ?