计算出平面上二条线段的相交点

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
namespace DrawLibrary
{
public enum EndPoint : short
{
Start = 0,
End = 1
}
public class Line {
Point _BeginPoint;
Point _EndPoint;

public Line(Point BeginPoint, Point EndPoint)
{
_BeginPoint = BeginPoint;
_EndPoint = EndPoint;
}

public Point BeginPoint
{
get { return _BeginPoint; }
}
public Point EndPoint
{
get { return _EndPoint; }
set
{
_EndPoint = value;
}
}

}
public class Utils
{
public static PointF PointToF(Point p)
{
return new PointF(p.X, p.Y);
}

public static Point PointFromF(PointF p)
{
return new Point((int)p.X, (int)p.Y);
}

public static EndPoint OtherEndpoint(EndPoint which)
{
return (which == EndPoint.Start) ? EndPoint.End : EndPoint.Start;
}