Where can I find code to change InstrumentWidget(Attitude/Compass)?

Hello, This is new comer and now studying about entire of QGroundControl.
I found that there is something structure seems to be a widget shows attitude and heading of a vehicle

in src/FlightMap/Widgets,

└ QGCCompassWidget.qml
└ QGCAttitudeWidget.qml
└ QGCPitchIndicator.qml

by the way, which file changes or passes data effects to change status of above widget?

I guess some file(s) in src/QmlControls does control if sensor data received from the connected vehicle
I cannot assure that which exact file does transition of graphic widget.

Thank you in advance.