     /**
      * 坐标原点的位置,位置是相对位置，默认是(0,0), 假如设置为(0.5,0.5)则在视图的中间。
      */
-    public var origin : CGPoint = CGPoint(x: 0, y: 0) {
+    public var origin : CGPoint = CGPoint.zero {
         
         didSet{
             if !oldValue.equalTo(origin){

     * 恢复默认设置
     */
    public func reset(){
        
    }
}


     */
    public var start = -CGFloat.greatestFiniteMagnitude {
        didSet{
            if start != oldValue {
                pathLayout?.setNeedsLayout()
            }
        }
    }
    
    public var end = CGFloat.greatestFiniteMagnitude {
        didSet{
            if end != oldValue {
                pathLayout?.setNeedsLayout()
            }
        }
    }
    
