Fix: PDF thumbnails to WEBP/AVIF

[AhmarZaidi]

Summary

This PR adds support for generating Modern Format (webp/aif) image thumbnails from PDF files.

Fixes #1766

Relevant technical choices

• Added application/pdf mimetype to the default transforms list and use get_attached_file() function for getting the original pdf file path if mime type is application/pdf to bypass $image_path = wp_get_original_image_path( $attachment_id );
• Add unit tests for web uploads helper functions to check if 'application/pdf' is included in the MIME transforms array.

Screen records

https://github.com/user-attachments/assets/9a4f940f-3860-43e3-9aa2-4e252e10ff34

[AhmarZaidi]

As mentioned in the issue comment, the solution doesn't seem work when we test it on the dev environment run using npm run wp-env start and shows security policy error:

WP_Error Object
(
    [errors] => Array
    (
        [invalid_image] => Array
        (
            [0] => attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/426
        )
    )

    [error_data] => Array
    (
        [invalid_image] => /var/www/html/wp-content/uploads/2025/02/test.pdf
    )

    [additional_data:protected] => Array ()
)

This appears to be an issue with ImageMagick policy used in the docker WordPress environment. Solutions suggest changing the ImageMagick policy

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 68.65%. Comparing base (6274111) to head (2306f64).

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #1868      +/-   ##
==========================================
+ Coverage   68.64%   68.65%   +0.01%     
==========================================
  Files          90       90              
  Lines        7969     7972       +3     
==========================================
+ Hits         5470     5473       +3     
  Misses       2499     2499              

Flag	Coverage Δ
multisite	68.65% <100.00%> (+0.01%)	:arrow_up:
single	35.36% <100.00%> (+0.02%)	:arrow_up:

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[phanduynam]

This issue has been resolved, please close it admin

[westonruter]

@AhmarZaidi Hey! Are you planning to pick this up?

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Co-authored-by: AhmarZaidi <[email protected]>
Co-authored-by: westonruter <[email protected]>
Co-authored-by: phanduynam <[email protected]>
Co-authored-by: adamsilverstein <[email protected]>
Co-authored-by: 1ucay <[email protected]>

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[AhmarZaidi]

Hey @westonruter

I've updates the branch and marked it as ready for review, let me know if any changes are required.

[adamsilverstein]

@AhmarZaidi thanks for this PR, great idea! I'm curious if you have tested on a system that uses GD instead of Imagick. Since GD doesn't support extracting PDF thumbnails, I want to make sure adding the mapping doesn't have any unintended consequences.