[wp-trac] [WordPress Trac] #34955: The choices of images to add to srcset shouldn't be via a ratio

[WordPress Trac]

#34955: The choices of images to add to srcset shouldn't be via a ratio
--------------------------------------+------------------------
 Reporter:  smerriman                 |       Owner:  joemcgill
     Type:  defect (bug)              |      Status:  assigned
 Priority:  normal                    |   Milestone:  4.4.1
Component:  Media                     |     Version:  4.4
 Severity:  normal                    |  Resolution:
 Keywords:  has-patch has-unit-tests  |     Focuses:
--------------------------------------+------------------------

Comment (by smerriman):

 What if you do use a pixel difference, but always in reference to
 shrinking the larger size to the smaller size, whichever way around it is?

 That is, if your current image is axb and you want to see if cxd should be
 added to the srcset:

 If c>a and the srcset image was used, the axb image would be replaced by
 ax(d*a/c), so check if |b-d*a/c|<=1.

 If c<a, the only time the srcset image will be used if it has been shrunk
 with CSS to at most c wide already. So it's actually being display at
 cx(b*c/a) initially and being replaced by cxd, so check if |d-b*c/a|<=1.

 I think this solves the original issue of 480x188 and 4000x1563 - because
 rather than comparing 4000x1537 with 4000x1567.66 which fails, you'd be
 comparing 480x188 and 480x187.56, which succeeds.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/34955#comment:8>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform