views – How do I get the location of a user’s device?

I’m working on a tourism project. There are places in the city, which are stored as Geofields in the content type. These fields are then represented together in a view map (Leaflet).

How can I get the location of the user’s (mobile) device, so it will be shown as a dynamic HTML5 positioning (or even static) marker? I already installed Geocoder and added the Freegeoip provider. However, I haven’t found enough documentation related to this topic.

It has to work with open source solutions.