实现GIS的一般量测功能，如距离量测，面积量测等。仿照Arcgis的量测工具所做。希望大家喜欢，也是在网上下载的开源的。-Measurement to achieve the general GIS functions such as distance measurement, area measurement and so on. Measurement tool modeled Arcgis made. Hope you like them, but also in the open sou