Changing Rotation angle in Edit image (editor-image-popup)

Is it possible to change rotation angle when using rotation button in the tool Popup Edit Image used in different Editors (Image pairing, Image sequencing, Drag and Drop, Course Presentation...). I have some rounded shape png images and I want the editor user can change by rotation of 45° this image without having to load a new image.
I have seen that event click on this button call a function() {  this.rotate(90)}, but i don't know where i can change code to have function() {  this.rotate(45)}.