Replacing tub with shower

[nyltak]

I am taking out the tub, putting in a shower, but also putting a new entry door into the bathroom where the tub was. Cement Slab floor.
Basically I wanted to put the shower about 48 inches north of where the tub is but the drain vent is in the way. I am wondering could I just swap the vent and the drain? I'd have to put in an angle on the drain to connect it and make it the new vent. sounds easy enough, but will I be able to put a p trap where the vent was after I cut down into the cement?
Or is there any reason I couldn't just cut the cement around the vent, and move it towards the eastern wall and continue to use the old drain. (see image)

If anyone has any options, or a simple solution that my zero plumbing experience mind has failed to see, I would love any insight. Thanks in advance.

 

[CountryBumkin]

The vent needs to be between the trap and the sewer line. If you just swapped their function the vent would be on the wrong side of the trap.