Orientation in Android

Hi guys,
I need something from your brain and mind d^_^b.
Here's the issue :
I need to know how do android device managing it's orientation? I mean, how do I know it will get Landscape or Portrait or else (on what degree of obliquity).

I got these code :

  float angle = event.vector.roll;
if(angle >= 45 && angle < 135)
		newOrientationType  = OET_ASPECTLANDSCAPE_LEFT;
	else if(angle >= 135 && angle < 225)
		newOrientationType = OET_ASPECTPORTRAIT_REVERSED;
	else if(angle >= 225 && angle < 315)
		newOrientationType = OET_ASPECTLANDSCAPE_RIGHT;
	else
		newOrientationType = OET_ASPECTPORTRAIT;

Here's the clue of above :
angle : determined how much device has been tilted
newOrientationType : determined the orientation.

The question is : "When's 45,135,255,and else degree for the devices?"

Ok, that might be unclear.

So watch this :

^ ^
_ _ , is the normal position (but what degree??) (OET_ASPECTLANDSCAPE_RIGHT)

| >
| > , what degree?? (OET_ASPECTLANDSCAPE_LEFT)

\
\ , what degree?? (OET_ASPECTLANDSCAPE_LEFT)

Note : "_ _" : position of device

"^" and ">" : device's screen facing to (as for the (3), diagonal, it's should be facing 45 degree (top right).

Thanks

Tags: C++, Lua, Mobile Apps (Android)