C#使用自己写的海龟绘图类绘制递归分型树

 

paython里有个库，叫turtle，俗称海龟作图。自己看《程序员的数学》时，在递归章节看了用海龟绘图画递归树，我想用C#在winform上用gdi+去实现，我却没有在网上找到有适合C#语言的类似的库，我就自己简单写了一个海龟作图帮助类，实现了上图的图案。代码如下：

 public class TurtleHelper : IDisposable
    {
        private Graphics g;
        private int len = 30;
        private int curDegree = 0;
        public int degree = 15;
        private Point curPos;
        private Pen pen =null;

        private Stack<Point> stPoints;


        public TurtleHelper(Graphics g, Point basePoint)
        {
            this.g = g;
            this.curPos = basePoint;
            pen = Pens.Black;
            stPoints = new Stack<Point>();
           
        }

        public void left()
        {
            this.curDegree += this.degree;
        }

        public void right()
        {
            this.curDegree -= this.degree;
        }

        public void forward()
        {
            stPoints.Push(curPos);
            Point nextPoint = default;
            nextPoint.X =(int) (curPos.X - Math.Sin(curDegree/180.0 * Math.PI) * this.len);
            nextPoint.Y = (int)(curPos.Y - Math.Cos(curDegree / 180.0 * Math.PI) * this.len);
            this.g.DrawLine(pen, curPos, nextPoint);
            curPos = nextPoint;
           
        }
        public void back()
        {
            if(stPoints.Count>0)
            {
                var p = stPoints.Pop();
                curPos = p;
            }
        }

        public void Dispose()
        {
            g.Dispose();
        }


        
    }

三角函数，度数需要换算成弧度值，以上实现了海龟作图的基本方法，然后在窗体画递归树的代码：

TurtleHelper helper = null;

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            helper = new TurtleHelper(e.Graphics, new Point(350, 350));
            drawtree(7);
            helper.Dispose();
        }

        public void drawtree(int n)
        {
            if(n==0||helper==null)
            {
               return;
            }
            else
            {
                helper.left();
                helper.forward();
                drawtree(n - 1);
                helper.back();
                helper.right();
                helper.right();
                helper.forward();
                drawtree(n - 1);
                helper.back();
                helper.left();
            }
        }