Only attempt to get dominant colour for image mime types.

[peterwilsoncc]

Summary

Modifies the dominant colour detection function to use an allow list of mime types based on image types supported in WordPress. This prevents the feature from running on other media types such as video, zips, etc.

Fixes #1957

Relevant technical choices

Runs the colour detection on the supported mime types

$supported_mime_types = array(
	'image/jpeg',
	'image/png',
	'image/gif',
	'image/webp',
	'image/avif',
);

Introduces the filter dominant_color_supported_mime_types to allow third party developers to extend the feature.

Use of AI Tools

N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.21%. Comparing base (49f2d7a) to head (c07f4dd).
⚠️ Report is 12 commits behind head on trunk.

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2264      +/-   ##
==========================================
+ Coverage   69.17%   69.21%   +0.04%     
==========================================
  Files          90       90              
  Lines        7696     7703       +7     
==========================================
+ Hits         5324     5332       +8     
+ Misses       2372     2371       -1     

Flag	Coverage Δ
multisite	69.21% <100.00%> (+0.04%)	⬆️
single	35.41% <90.00%> (+0.05%)	⬆️

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[adamsilverstein]

Looks good to me.

[westonruter]

@peterwilsoncc Is this still a draft on purpose?

[Copilot]

Pull request overview

This PR restricts dominant color detection to supported image MIME types only, preventing the feature from attempting to process non-image attachments like videos or ZIP files. The change replaces a PDF-specific check with an allowlist approach.

Changes:

• Replaced the blocklist approach (checking for application/pdf) with an allowlist of supported image MIME types
• Added a filter hook to allow third-party developers to extend supported MIME types
• Updated error handling to return a more generic unsupported_attachment_type error

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[peterwilsoncc]

@peterwilsoncc Is this still a draft on purpose?

From memory I wanted to add a test but forgot to do so after 6.9 dropped. I've added it in 0e70a0c

[github-actions]

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Co-authored-by: peterwilsoncc <peterwilsoncc@git.wordpress.org>
Co-authored-by: westonruter <westonruter@git.wordpress.org>
Co-authored-by: adamsilverstein <adamsilverstein@git.wordpress.org>
Co-authored-by: kartikmehta8 <kartikmehta@git.wordpress.org>
Co-authored-by: sarthak-19 <sarthak8858@git.wordpress.org>

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