C＃使线高调整为椭圆

Question

使用以下代码绘制椭圆：

graphGraphics = e.Graphics;

graphGraphics.FillEllipse(new SolidBrush(Color.White), this.graphBoundries);
graphGraphics.DrawEllipse(graphPen, this.graphBoundries);

我在这张图上有一条线，它现在正好通过它。我想改变线条高度以适应椭圆的边界，如下所示它不会通过椭圆：

http://i1379.photobucket.com/albums/ah134/fac7orx2/circlewithlinehelp_zps280d9e76.png

有没有人知道这样做的算法？或者甚至可能只是如何获得椭圆的边界而不仅仅是矩形边界？

Answer 1

要扩展我的评论，请尝试使用此类（未经测试的）代码：

graphGraphics = e.Graphics;

graphGraphics.FillEllipse(new SolidBrush(Color.White), this.graphBoundries);
graphGraphics.DrawEllipse(graphPen, this.graphBoundries);

GraphicsPath clipPath = new GraphicsPath();
clipPath.AddEllipse(this.graphBoundaries);

graphGraphics.SetClip(clipPath, CombineMode.Replace);

// draw your line