A test code that I have written in Python by using Dronekit and OpenCV libraries. The simulated drone first takes off and starts to go to waypoint 1 then it moves between wp1 and wp2 until it finds a target. After finding the target it moves towards target to make it's position centered in the screen. Finally it starts to descend over target. Other libraries used: dronekit-sitl, mavproxy.
Demonstration: https://www.youtube.com/watch?v=as_aBcnOd-o