         }
     }
     
+    /// @IBDesignable support
     public override func prepareForInterfaceBuilder() {
         super.prepareForInterfaceBuilder()
         backgroundColor = UIColor.clearColor()

        }
    }
    
    override public var enabled: Bool {
        didSet {
            let state : UIControlState = enabled ? .Normal : .Disabled
            circleLayer.fillColor = circleColorForState(state)?.CGColor
            ringLayer.strokeColor = ringColorForState(state)?.CGColor
        }
    }
    
    func ringColorForState(state : UIControlState) -> UIColor? {
        switch state {
        case UIControlState.Normal: return ringColor
        case UIControlState.Highlighted: return ringColor

        return CGRectMake(innerX, innerY, innerWidth, innerHeight)
    }
    
    private func commonInit() {
        backgroundColor = UIColor.clearColor()
        
        ringLayer = CAShapeLayer()
