REST API: Expose size-aware encode quality on attachment responses - #11856

adamsilverstein · 2026-05-18T23:37:17Z

Summary

Adds an image_quality field to the media attachment REST response. It reports the value of the wp_editor_set_quality filter, resolved against the output MIME type (after image_editor_output_format):

default — the filtered quality (1-100) for the full-size image
sizes — per-registered-size overrides, included only where the filtered value diverges from default (keeps the payload small)

wp_editor_set_quality has been size-aware since 6.8 (( int $quality, string $mime_type, array $size )), so the filter is re-applied per registered sub-size using that size's dimensions.

This lets client-side media processing (which encodes sub-sizes in the browser) honor a site's configured encode quality instead of a hardcoded default, mirroring the existing exif_orientation field on the same controller.

Backports from Gutenberg

Media: Return the filtered wp_editor_set_quality value in the upload response gutenberg#78420

Testing

phpunit --filter test_image_quality — schema, default, and size-aware-filter cases
phpunit --filter test_get_item_schema — property count updated 32 → 33

Trac ticket: https://core.trac.wordpress.org/ticket/65262

Proposed commit message

REST API: Expose size-aware encode quality on attachment responses.

Add an `image_quality` field to the media attachment REST response reporting the `wp_editor_set_quality` filter value, resolved against the output MIME type after `image_editor_output_format`. The `default` key carries the filtered quality (1-100) for the full-size image, while `sizes` lists per-registered-size overrides only where they diverge from `default`. 

See related Gutenberg pull request: https://github.com/WordPress/gutenberg/pull/78420.

Props westonruter, timothyblynjacobs.
Fixes #65262.

Add an image_quality field to the media attachment REST response reporting the wp_editor_set_quality value resolved against the output MIME type. The default value applies to the full-size image; per-registered-size overrides are listed under sizes only where the filtered value diverges from the default. This lets client-side media processing encode images at the quality the site has configured, instead of a hardcoded default, mirroring the existing exif_orientation field. Props adamsilverstein.

github-actions · 2026-05-18T23:41:29Z

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TimothyBJacobs · 2026-05-19T00:06:20Z

Should there be a helper function extracted? Looks like quite a bit of logic that will need to stay in sync.

adamsilverstein · 2026-05-19T16:43:32Z

Should there be a helper function extracted? Looks like quite a bit of logic that will need to stay in sync.

My understanding is that the code will only live in Gutenberg only to support older WordPress versions where the helper wouldn't be available. I believe they only support back a few versions (2?) though, so it can get removed from Gutenberg after some time. Although a helper still might be useful to contain the logic, will consider.

Co-authored-by: Weston Ruter <westonruter@gmail.com>

Resolve the encode quality WordPress would apply for a given output MIME type and dimensions without instantiating an image editor, mirroring WP_Image_Editor::set_quality(): the per-format default, the wp_editor_set_quality filter, the jpeg_quality filter for JPEG output, and a clamp to the valid 1-100 range. This gives callers outside an editor instance, such as the REST API reporting the quality client-side processing should use, a single authoritative resolver instead of re-deriving the logic by hand.

Resolve image_quality through the new wp_get_image_encode_quality() helper so the reported value includes the legacy jpeg_quality filter for JPEG output (matching WP_Image_Editor::set_quality()) and stays in sync with core's quality logic instead of duplicating it for the full size and each sub-size. Bound the schema integers to 1-100 and enumerate the registered sub-sizes under "sizes" so the schema documents exactly which keys may appear.

adamsilverstein · 2026-05-21T20:05:12Z

Pushed updates addressing the review:

@TimothyBJacobs extracted the shared logic into wp_get_image_encode_quality( $mime_type, $size, $default_quality ) in wp-includes/media.php. The Gutenberg PR now calls this funciton if available.
- I left WP_Image_Editor::set_quality() itself untouched here: the canonical docblocks for wp_editor_set_quality/jpeg_quality live in that method and are referenced across core via "documented in wp-includes/class-wp-image-editor.php", so having set_quality() adopt the helper is cleaner as a follow-up. Happy to do it in this PR if you'd prefer.
@westonruter the reported value now includes jpeg_quality for JPEG output, the schema integers are bounded 1-100, and sizes enumerates the registered sub-sizes.
Added unit tests for the helper (defaults, both filters, out-of-range clamping) and a jpeg_quality case on the REST response.

Replace the placeholder ticket number now that the canonical ticket is open (the duplicate was closed).

…ontroller.php Co-authored-by: Weston Ruter <westonruter@gmail.com>

wp_get_image_encode_quality() clamped values above 100 to 100, which diverges from WP_Image_Editor::set_quality(): that method resets any out-of-range value (below 0 or above 100) to the per-format default and only squashes 0 to 1. Mirror that behavior so the REST-reported quality matches what the server actually applies, and so the clamps-out-of-range test (150 -> 82, 0 -> 1) passes.

github-actions · 2026-06-29T15:50:38Z

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props adamsilverstein, westonruter, timothyblynjacobs.

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adamsilverstein · 2026-06-29T15:52:36Z

Should there be a helper function extracted? Looks like quite a bit of logic that will need to stay in sync.

My understanding is that the code will only live in Gutenberg only to support older WordPress versions where the helper wouldn't be available. I believe they only support back a few versions (2?) though, so it can get removed from Gutenberg after some time. Although a helper still might be useful to contain the logic, will consider.

moved logic to a helper as suggested. GB now consumes from this function if available - https://github.com/WordPress/gutenberg/pull/78420/changes#diff-2a14b3375a43081acbcd01a95fe0441eb10ff35c57d9161860d79bdbd3bf2becR998

…ty-field # Conflicts: # src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php # tests/phpunit/tests/rest-api/rest-attachments-controller.php

…t_image_encode_quality()

Apply Weston's suggestions from the review and mirror the minor robustness changes he amended to the core counterpart (WordPress/wordpress-develop#11856) so the two stay in sync: - Accept the PHPStan-typed docblock on the encode-quality helper and add native type hints, renaming the parameter to $mime_type to match the core wp_get_image_encode_quality() signature. - Cast get_post_mime_type() to string and clamp the full-size dimensions to non-negative ints before deriving quality. - Add the out-of-range reset comment and drop the redundant int cast on return so the inline fallback mirrors core exactly.

adamsilverstein · 2026-07-02T03:37:54Z

Thanks for the reviews @westonruter - I've aligned this as closely as possible with the Gutenberg PR and both should be ready to go.

…ty-field # Conflicts: # src/wp-includes/media.php

westonruter · 2026-07-02T16:49:17Z

oh, there is a PHPUnit failure:

There was 1 failure:

1) WP_Test_REST_Attachments_Controller::test_sideload_animated_video_companions_write_metadata
Sideloading animated_video should succeed.
Failed asserting that 400 is identical to 200.

/var/www/tests/phpunit/tests/rest-api/rest-attachments-controller.php:3881
phpvfscomposer:///var/www/vendor/phpunit/phpunit/phpunit:106
/var/www/vendor/bin/phpunit:118

adamsilverstein · 2026-07-02T22:21:04Z

oh, there is a PHPUnit failure:

That was from another commit and should be fixed in trunk. Updating to be sure.

github-actions · 2026-07-02T23:15:15Z

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 62630
GitHub commit: 4d6a707

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.

adamsilverstein self-assigned this May 19, 2026

westonruter reviewed May 19, 2026

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andrewserong mentioned this pull request May 20, 2026

Media: Return the filtered wp_editor_set_quality value in the upload response WordPress/gutenberg#78420

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6 tasks

adamsilverstein mentioned this pull request May 20, 2026

Client Side Media iteration for WordPress 7.1: stabilization, docs, and Core backports WordPress/gutenberg#76756

Open

adamsilverstein and others added 3 commits May 21, 2026 12:50

Apply suggestions from code review

1c60f7b

Co-authored-by: Weston Ruter <westonruter@gmail.com>

Tests: Reference Trac ticket #65262 for image_quality coverage.

61b33fd

Replace the placeholder ticket number now that the canonical ticket is open (the duplicate was closed).

westonruter reviewed May 21, 2026

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Comment thread src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php Outdated

adamsilverstein mentioned this pull request May 22, 2026

Media: Re-introduce client-side media processing feature #11324

Closed

5 tasks

adamsilverstein and others added 3 commits May 28, 2026 13:50

Update src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-c…

824ee07

…ontroller.php Co-authored-by: Weston Ruter <westonruter@gmail.com>

Add types and address PHPStan issues with wp_get_image_encode_quality()

393e27c

adamsilverstein marked this pull request as ready for review June 29, 2026 15:50

adamsilverstein requested review from TimothyBJacobs, swissspidy and westonruter June 29, 2026 15:53

adamsilverstein mentioned this pull request Jul 1, 2026

PHP backports for WP 7.1 WordPress/gutenberg#79304

Open

adamsilverstein and others added 5 commits July 1, 2026 13:52

Merge remote-tracking branch 'origin/trunk' into add/rest-image-quali…

2436b94

…ty-field # Conflicts: # src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php # tests/phpunit/tests/rest-api/rest-attachments-controller.php

Fix param type for $default_quality

8a2aca7

Add return type info for wp_get_registered_image_subsizes()

ae86911

Ensure non-negative-int values are used in dimensions passed to wp_ge…

7e0501e

…t_image_encode_quality()

Fix assign.byRefForeachExpr

f20e7df

Cast mime_type to string since guaranteed to be so

5bc92b3

westonruter reviewed Jul 1, 2026

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Comment thread src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

westonruter reviewed Jul 1, 2026

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Comment thread src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

westonruter approved these changes Jul 1, 2026

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Merge remote-tracking branch 'origin/trunk' into add/rest-image-quali…

48706d1

…ty-field # Conflicts: # src/wp-includes/media.php

westonruter approved these changes Jul 2, 2026

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Merge branch 'trunk' into add/rest-image-quality-field

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Backports from Gutenberg

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