// show real degree depending Min/Max Angel
why you just not add a new property for example actual value to show real angle?
You have all data and this is not any depending is this is compass or other custom buisness logic control.
Or may be this functionality is done? How to get actual angle from control?
For my compass example if Value is equal to 450, angel is 90 degree.
Or you can simply show fuction that set needle to 90 degree.