[wp-trac] [WordPress Trac] #39813: Add_Image_Size: Extra Parameter - Limit thumbnail-size generation to custom post type

[WordPress Trac]

#39813: Add_Image_Size: Extra Parameter - Limit thumbnail-size generation to custom
post type
-------------------------+-----------------------------
 Reporter:  tifosi       |      Owner:
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:  Awaiting Review
Component:  Media        |    Version:  4.7.2
 Severity:  normal       |   Keywords:
  Focuses:               |
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 I noticed a thread on the forum which itched a frustration I increasingly
 have with image handling in WordPress, particularly after v3. I couldn't
 see any related TRAC enhancement request.

 [https://wordpress.org/ideas/topic/limit-thumbnail-size-generation-to-
 custom-post-type/]

 For complex CMS-style sites that have extensive usage of custom post
 types, taxonomies, and meta data - using the increasingly available
 plugins like ACF for image meta, it is quite often that a site will
 register multiple calls to add_image_size to provide all the template
 layouts required.

 Herein lies the problem: add_image_size is agnostic to the image size and
 simply iterates through the registered intermediate image sizes to
 generate an image for each size, irrespective of whether it's ever needed,
 or will be used.

 Add on the generic Wordpress sizes: thumbnail, medium, large etc and you
 have a recipe for a file system full to the brim with useless images.

 It would be extremely useful for the function to have:
 1. An additional parameter to restrict the post_type usage via the
 intermediate_sizes global probably, so that dynamic image generation has
 some direction.
 2. A filter to restrict the image generation, e.g
 add_{post_type}_image_size:
 {{{
 add_filter( 'add_event_image_size', function( $sizes ) { return
 ['event_thumbnail', 'event_category' ]; }, 10,1);
 }}}
 Thinking out loud on that one, depends on the codebase.
 3. Both.

 Really hope that when the current 4.7-4.8 focus on the WP-API is completed
 that a new focus on media handling is looked at. This is a feature
 requested by many, and needed for a while.

 Noted enhancements: #35775, #15311

 Thanks

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Ticket URL: <https://core.trac.wordpress.org/ticket/39813>
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