[wp-trac] [WordPress Trac] #44299: Cropped images have wrong ratio

[WordPress Trac]

#44299: Cropped images have wrong ratio
--------------------------+-----------------------------
 Reporter:  tschortsch    |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  General       |    Version:  4.9.6
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 There seems to be a problem in the `image_resize_dimensions()` function
 when `$crop` is set to `true`.

 Here's an example:
 I defined 3 cropped sizes with the same ratio (1:1):
 - large-crop: 1250x1250
 - medium-crop: 1000x1000
 - small-crop: 500x500
 When I upload an image with a size of 1250x1000px I get the following
 sizes:

 {{{
 [large-crop] => Array
 (
     [file] => 1250x1000-1250x1000.png
     [width] => 1250
     [height] => 1000
     [mime-type] => image/png
 )
 [medium-crop] => Array
 (
     [file] => 1250x1000-1000x1000.png
     [width] => 1000
     [height] => 1000
     [mime-type] => image/png
 )

 [small-crop] => Array
 (
     [file] => 1250x1000-500x500.png
     [width] => 500
     [height] => 500
     [mime-type] => image/png
 )
 }}}

 As you can see the large-crop size gets generated with a wrong ratio
 (5:4). When I now load this size `wp_get_attachment_image_srcset(
 $attachment_id, 'large-crop' )` the `srcset` gets calculated with other
 images that have a 5:4 ratio (if existing). I would expect to get a
 `srcset` of images with a 1:1 ratio.

 When I upload an image with a size of 1100x1000px (smaller than large-
 crop) something similar happens. The `large-crop` doesn't get generated at
 all. When I load the image with this size `wp_get_attachment_image_srcset(
 $attachment_id, 'large-crop' )` it falls back to the original size (since
 the size is not available). The original image has a ratio oh 11:10 which
 means the calculated `srcset` consists of images with a wrong ratio.

 I tracked this problem down to the `image_resize_dimensions()` function
 and created a possible fix for it here:
 https://github.com/rokka-io/rokka-wordpress-plugin/blob/fix-srcset-
 calculation/src/class-wp-crop-bugfix.php#L57

 I also created some unit tests which shows the original behaviour and the
 behavior after the bugfix:
 https://github.com/rokka-io/rokka-wordpress-plugin/blob/fix-srcset-
 calculation/tests/test-wp-crop-bugfix.php

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/44299>
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