This mobile plugin functionality is to count the distance (in mile or kilometer) of GPS Coordinate (Latitude, Longitude) between 2 point. 

The count process is on the server side.

Below is the example on how to use this plugin.

CountDistance server action with this parameter :

Distance as result (Decimal)

IsMetricSystem as parameter to check using Kilometer (True) or Mile (False)

Lat_Center, Lng_Center as parameter the center coordinate

Lat_Compare, Lng_Compare as parameter of the location that will be compare to center