Diagram Symbol Library System Design Methodology Based On Com Technology Flood Disaster Reduction Subject

Being an effective tool to obtain, manage, operate and display geographic information, Geographic Information System (GIS) is applied wider day by day. Waterflood Salvation System is a information system based GIS platform.Symbol Library System is a sub System of Waterflood Salvation System,it supplies the basic symbol library and symbol editing enviroment, resolving the problem that some symbol realize inaccurately, supplies high-quality appearance and readness.This paper firstly researched and analyzed the component technology. And then using the architecture and implement method of several famous GIS for reference,using Component Based Development(CBD) technique, the category and the function of map symbol variables are analyzed from the point of view of map language. The definition and the designing theory of Map Symbol Base are brought forward. On the base of deep study on the rule of composition of a picture and the structure theory of point line area symbols, a storage data structure of symbol base is designed. And a structure of program class is also designed by means of Component Based Development. Finally an experiment system and the results are introduced simply, and some farther problem to research and solve right along is put forward.