Location aware app

Krav

When I'm at home I use the app for all sort of things.
When I use the app when not at home I'm usually shopping and scanning labels.
So my request is this.
Mark your home location with the phone's GPS.
When 100m away from that point consider not at home.

If I start the app at home it starts as it always starts.
If I start the app while not at home it starts with the scanner active.