本文阐述了基于COM/ActiveX技术的GIS的理论基础、概念及其特点，并以Delphi和Mapobjects为工具，结合需求介绍了基于Web GIS的房地产信息发布系统的开发过程，并对开发过程中若干关键技术进行了详细说明。-this paper based on the COM / ActiveX technology GIS theoretical foundation, the concept and its features, and to Delphi and Mapobjects

A program on Delphi which is a combination of usual and ingeneer calculator.