DEP: Remove paeth_predictor

[j-t-1]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.11%. Comparing base (1d9d3bc) to head (413f3d0).
Report is 81 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2773      +/-   ##
==========================================
- Coverage   95.12%   95.11%   -0.01%     
==========================================
  Files          51       51              
  Lines        8555     8545      -10     
  Branches     1706     1704       -2     
==========================================
- Hits         8138     8128      -10     
  Misses        263      263              
  Partials      154      154              

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[stefan6419846]

IMHO this just reduces readability instead of really simplifying it.

[j-t-1]

Maybe there is another way to refactor to avoid the if statement, as this is just a map reduce.

[j-t-1]

paeth_predictor is only used to test itself; it is not used elsewhere. The functionality of this function is at line 221 of filters.py.

1. We remove paeth_predictor.
2. We use paeth_predictor in filters.py.

Thoughts?

[stefan6419846]

There apparently have been plans by @MartinThoma to deprecate and finally drop this method in #2068 (comment), but for now this apparently did not have any real priority.

[j-t-1]

Thanks @stefan6419846.

What about moving paeth_predictor to filters.py (it is only used in this file) and calling it within _decode_png_prediction.

[stefan6419846]

Where is it used in filters.py? As far as I have seen, it is used nowhere and thus most likely can be removed. (As it is not part of a public module, we could even avoid the deprecation.)

[j-t-1]

The body of paeth_predictor is on line 221.

[stefan6419846]

I have to admit that I did not look for code copies, thus my search would not see this. Therefore just keeping it does not make much sense either.

[pubpub-zz]

I agree to remove it.