有时候需要改变一下线的方向来组成要要的图形，可以按一下方法来变换一下。
如果看官有好的方法的话，请不吝贴上为谢！
private IPolyline ChangeDirection(IPolyline polyline)
{
IPointCollection pointCollection = polyline as IPointCollection;
IPointCollection newPC = newPolylineClass();
for (int i =pointCollection.PointCount - 1; i >= 0; i--)
{
newPC.AddPoint(pointCollection.get_Point(i), mis, mis);
}
IPolyline newPolyline = newPC as IPolyline;
}