I want to draw a uniformly-spaced set of tic marks along two edges of an image that may have been clipped and interpolated to a different pixel density. I would like to specify the tic mark spacing in terms of number of pixels per tic mark or something similar. Currently I have Affinity Photo and suspect that Affinity Designer would more likely be able to do something like this. Can someone please explain how this might be done and which app can do it?
I sort of answered my own question. Using Affinity Designer I drew a short horizontal line, duplicated the line at uniform intervals, selected the lot, and grouped them. I can duplicate, rotate, and stretch the group to set the line spacing to whatever I want. I can also ungroup, add or remove lines, and regroup. Maybe that's not the easiest way but it will do for now.