I haven't tried the screenshot method, but just to note about FPs. The print at home ticket (e-ticket) won't work for FPs; you need to redeem the e-ticket at the gate or ticket booth (depending on where you purchased your ticket) first. When you do that, they'll give you a credit card sized ticket. You can use this for subsequent entrances and to get FPs from the kiosks.
For the screen shot, as long as the barcode is clearly visible, it should work. They need to be able to scan that, so make sure that part of the ticket is very clear in your screen shot.