After a path bracket is open, an application can begin calling GDI drawing functions to define the points that lie in the path. An application can close an open path bracket by calling the EndPath member function. When an application calls BeginPath, any previous paths are discarded.http://msdn2.microsoft.com/en-us/library/c8ezcwxf(VS.80).aspx
以下代码可以获取椭圆上所有的顶点. dcResult.BeginPath();
dcResult.Ellipse(&rc);
dcResult.EndPath();
dcResult.FlattenPath();
unsigned long lNumPoints = dcResult.GetPath(NULL, NULL, 0);
pts.resize(lNumPoints);
vector<BYTE> Bytes(lNumPoints);
dcResult.GetPath(&pts[0], &Bytes[0], lNumPoints);