Detect GPIO pins on boot and make decision accordingly

@WayneWWW ,
My concern with the login screen is that “I think” it’s not allowing me display my output using Opencv, After I login the app runs fine, and displays as expected,however I need the application to display its output on the screen automatically after startup.
I am talking about the Gui login screen.
I tried the solution of this thread, but I am still stuck on the login screen: