code: function calculateAngle(startPoint, endPoint) {
  			var x = startPoint.x - endPoint.x;
  			var y = endPoint.y - startPoint.y;
  			var r = Math.atan2(y, x); //radians
  			var angle = Math.round(r * 180 / Math.PI); //degrees
  
  			//ensure value is positive
  			if (angle < 0) {
  				angle = 360 - Math.abs(angle);
  			}
  
  			return angle;
  		}
docs: Calculate the angle of the swipe
  @param {point} startPoint A point object containing x and y co-ordinates
  @param {point} endPoint A point object containing x and y co-ordinates
  @return int
  @inner