[wp-trac] [WordPress Trac] #57685: Deprecate the `edit_custom_thumbnail_sizes` filter and remove the "Apply changes to..." UI in the image editor

[WordPress Trac]

#57685: Deprecate the `edit_custom_thumbnail_sizes` filter and remove the "Apply
changes to..." UI in the image editor
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 Reporter:  azaozz        |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  6.3
Component:  Media         |     Version:  6.0
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:
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Comment (by peterwilsoncc):

 There are two ways responsive images can be broken:

 * (major) different crops are included in the `srcset`, for example
 [https://peterwilson.cc/uploads/2013/05/b313f2e2ba9711e2aae322000a1f9858_7.jpg?crop=50px,300px,255px,255px&w=150
 this close up crop] in included in the `srcset` for a
 [https://peterwilson.cc/content/uploads/2013/05/b313f2e2ba9711e2aae322000a1f9858_7.jpg
 zoomed out crop].
 * (minor) editing an image results in no `srcset` being added. This means
 small screen devices download the full size image.

 The first item is a major break as `srcset` is speced that the crop is
 identical in all image. The second item is a minor break as the image
 displays correctly but the download is not optimal.

 **Testing notes**

 Major breaks can not happen as the `srcset` due to the use of edit hashes,
 eg `duck-e1676350656850-150x150.jpg`. The functionality adding `srcset`
 attributes ignores images with a different edit hash.

 Minor breaks can happen if a single size is regenerated as none of the
 other images will include an edit hash. For thumbnails this isn't much of
 an issue but for larger images it can result in unnecessarily large
 downloads.

 I tend to agree that editing sizes individually can be enough of a problem
 that it should probably be removed from core.

 As allowing users to edit thumbnails only can be of use for certain
 images, if it were to be removed from core it would be good to move it to
 a canonical plugin.

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Ticket URL: <https://core.trac.wordpress.org/ticket/57685#comment:2>
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