First of all, sorry for asking a question not actually directly related to DataObjectManager. I'm asking here because this is the place where I'm actually likely to get an answer. I'm in the situation that I need to do some image manipulation that's not included in SilverStripe.
I have been reading the GD and Image classes but so far I haven't been able to find a way to simply get the file/GD resource from them, do my manipulation and then return it. Optimally I want SilverStripe to treat my new image in the way it treats thumbnails and the like so I actually still have the old image but also have access to the my modified image.
If anyone knows how to go about this I would very much like to hear from you!
Once again, I'm sorry for asking here but I'm kind of desperate.
Your solution looks alot like what I've been trying since asking the question, namely grabbing the image myself and doing raw GD work and then returning a new GD object with the new filename to make SilverStripe happy.
I'll read through all those threads to see if there's anything I've missed.