问一下，ClientToScreen功能 怎么接收用户定义的坐标

long CQMPlugin::ClientToScreen(long hwnd, VARIANT FAR* x, VARIANT FAR* y)
{

POINT pt;
pt.x = 675;
pt.y = 489;
::ClientToScreen((HWND)hwnd,&pt);

*x=COleVariant(pt.x);
*y=COleVariant(pt.y);

    return 1;
}


怎么把其中的675 489 改成用户自己定义呢