实现地图的距离及面积测算，源代码摘自别人的，放在我电脑上用的arcengine10.0,所以很多地方都需要修改，修改了后的现在是-Achieve Map distance and area calculations, the source code taken others, on my use of the computer arcengine10.0, so many places need to be modified, amended after it is