Drawing custom data on Mission Planner map?


I’m looking to add custom data to the Mission Planner map based on an external input combined with the GPS data being received from a drone.

More specifically, I’m looking to draw circles on the map every time a boolean ‘true’ flag is received from an external input, which will be polled every second (initially, this flag could be picked up by Mission Planner watching for changes to a file on disk to keep things simple).

I’ve cloned the MP repo to start taking a look, and was wondering if someone has done something similar before or could point me to the best in the codebase to add this custom functionality?

Apologies if this is the wrong place for this query, I’m new to Mission Planner (I’m helping someone out with their project).

Thanks in advance!