C# 调整行高为椭圆

Question

有一个椭圆是用下面的代码画的：

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，它目前刚好穿过它。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

有人知道执行此操作的算法吗？或者甚至可能如何只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，请尝试这样的（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

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