C#使行高调整为椭圆

Question

有一个椭圆用以下代码绘制：

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，它目前正好穿过它。我想改变线条高度以适应椭圆的边界，如下所示，这样它就不会穿过椭圆：

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

有人知道这样做的算法吗？或者甚至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，请尝试以下代码（未经测试）：

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