getAngle method
Returns the degree of this segment. 0 means vector to the right side --> Since positive values in y-direction points towards the bottom of the screen the angle runs clockwise.
Implementation
double getAngle() {
if (_angle != null) return _angle!;
_angle = atan2(end.y - start.y, end.x - start.x);
_angle = toDegrees(_angle!);
return _angle!;
}