The Research of Extending Components GIS——The Design to Extend Component Using Outgoing Interface
Rong Kai · Geo-information Science · 2003
With rapid development of GIS in recent years, the trend of components GIS has become more and more popular But because of the encapsulation essence of the object oriented model, programmers can only use the interfaces to communicate with the object without knowing anything about the realization details They will get into dilemma when they encounter those functions that GIS components can not realize In this circumstance, the outgoing interface defined by the GIS components can be used to extend the GIS components to realize those functions This article will introduce how to use the outgoing interface to customize the symbols in MapObjects and illustrate the mechanism of the process Meanwhile, the article will also introduce how to add an outgoing interface when developing GIS components Finally, the article discusses the possible trend of this mechanism