The effect you would like to display to the user, usually indicating what would happen if a drop occurred at this point with the selected data. Typically, this is the value returned by the most recent call to CView::OnDragEnter or CView::OnDragOver.

由已知的两个经纬度点求其间的距离和方位；已知一个坐标点，和相对于这个点的距离方位，求目标点的经纬度-Latitude and longitude points from the two known distance and azimuth during demand given a coordinate point, and the relative distance and orientation of this point, find the target point of latitud