Image processor: How to make focal point take effect when calling myimage.jpg?anchor=center&mode=crop&width=xxx&height=yyy?

I have a site where image src´s are inserted on the fly by JavaScript (to ensure images have the exact dimensions needed). Therefore image src´s are not known by backend code and therefore I call images urls this way:

myimage.jpg?anchor=center&mode=crop&width=xxx&height=yyy

My problem is: How do I build up the url so it takes the focal point set by editor in backend into account?

Does something like this work?

myimage.jpg?anchor=center&mode=crop&width=500&height=200&focal=-30,-20 

where “focal=-30,-20” tells where to place focus according to the image center?


This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/104463-image-processor-how-to-make-focal-point-take-effect-when-calling-myimagejpganchor-centermode-cropwidth-xxxheight-yyy