VirtualJoystick constructor
Creates a new virtual joystick.
Implementation
VirtualJoystick() : super(new Size(160.0, 160.0)) {
userInteractionEnabled = true;
handleMultiplePointers = false;
position = new Offset(160.0, -20.0);
pivot = new Offset(0.5, 1.0);
_center = new Offset(size.width / 2.0, size.height / 2.0);
_handlePos = _center;
_paintHandle = new Paint()
..color=new Color(0xffffffff);
_paintControl = new Paint()
..color=new Color(0xffffffff)
..strokeWidth = 1.0
..style = PaintingStyle.stroke;
}