I for one really need this production capability!
To be clear, what I need (and I'm sure others are in the same boat) is the ability to specify a "base layer" or layers (like a background pattern, logo, watermark, etc.) beneath/above which other layers are to be added, either individually or in groups, and then exported as fully composed individual files.
For example, I'm doing a t-shirt design on multiple colors of shirts. The final, composed files for each color of shirt will all have the same drop shadow, background, logo, text, etc. If there were a way to batch process export, it would be an enormous time, sanity and maybe life saver!
The document might look something like:
Layer 1: Logo
Layer 2: Main t-shirt graphic
Layers 3-15 (maybe in a set): Shirts of the same geometry (size and shape), but of different colors.
Layer 16: Shirt drop shadow
Layer 17: Contact/copyright info
Layer 18: Background
Of course, I can save off each composed piece of art (featuring a different colored t-shirt) separately, but this is time consuming and tedious, particularly when working with dozens of t-shirt designs! Computers are supposed to make repetitive tasks easy, right?
If this could be done with a SIMPLE, easy to use interface, so much the better.
I'm thinking there might be a toggle to "lock" all layers/groups which remain the same, and then another which is is labeled something like: "rotate thru images on save".
You then go to Export and voila -- you've now got separate, composed, final files for the different t-shirt colors!
Anyway, I love Affinity Photo, but when it comes to stuff like this, it's looking like I'm going to have to back to Photoshop (and it's dread scripting ability). Unless you can tell me otherwise, of course!
FOLLOWUP: After MANY HOURS of trying various software and searching, I found one app on Mac that does the job quickly and easily, if simplistically. You can load in a background, bulk upload a set of pics to be overlayed (in my case, .png files of t-shirts), and then batch output to a folder. It's NCH's Pixillion. FYI. It's even got a free trial. I still hope Affinity can come up with a more robust method of doing this. :-)