I like a guy at uni but can't tell if he is straight ot gay.. help?

This guy at my uni asked to take my photo (he is on the photgraphy course) later I found him on FB and asked if he would send me the photo he replied and said he would do it when he got a chance.

Two days later I bumped into him at the local uni bar and he approached me.

Him and his friend (maybe boyfriend?)

approached me, he was friendly and he spoke about the photo and said it looked "naughty" I asked what he meant he said a bit "perverted" the way I was smoking in it. Anyway I guess my question is , do you think this guy is gay and just being friendly? or is he straight?

I have a few gay friends but also straight guys that act camp so I don't know....