C# 从圆边到圆边画线

Question

假设我有 2 分

Point p1 = new Pen(100, 100);
Point p2 = new Pen(200, 150);

然后我用给定的半径为该点绘制椭圆，该点位于椭圆的中心。

int radius = 5;
RectangleF rectangle = new RectangleF();
rectangle.Width = radius  * 2;
rectangle.Height = radius  * 2;
rectangle.X = Convert.ToSingle(p1.X - radius);
rectangle.Y = Convert.ToSingle(p1.Y - radius);
g.FillEllipse(brush, rectangle);
rectangle.X = Convert.ToSingle(p2.X - radius);
rectangle.Y = Convert.ToSingle(p2.Y - radius);
g.FillEllipse(brush, rectangle);

g.DrawLine(pen, p1, p2);

如果我在这些点之间画线，我会得到从一个中心到另一个中心的线。目前我可以接受，但我想做的是，这条线从椭圆的边缘开始，所以它不会穿过它。我怎样才能做到这一点？

Answer 1

找到答案:

    public static PointF getPointOnCircle(PointF p1, PointF p2, Int32 radius)
    {
        PointF Pointref = PointF.Subtract(p2, new SizeF(p1));
        double degrees = Math.Atan2(Pointref.Y, Pointref.X);
        double cosx1 = Math.Cos(degrees);
        double siny1 = Math.Sin(degrees);

        double cosx2 = Math.Cos(degrees + Math.PI);
        double siny2 = Math.Sin(degrees + Math.PI);

        return new PointF((int)(cosx1 * (float)(radius) + (float)p1.X), (int)(siny1 * (float)(radius) + (float)p1.Y));
    }