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Track: Application Development Techniques
Guchuan Liu
Psomas and Associates
600 South Spring Street Suite 1608
Los Angeles, CA 90014
Telephone: 213-623-3905
Fax: 213-623-3813
E-mail: gliu@psomas.com
Rick Ayers, Blake Murillo, Wing Tam
Using Visual Basic and MapObjects to Develop Mapping Applications
In 1995, Microsoft released one of its flagship products, Visual Basic 4.0 to software developers worldwide. Visual Basic 4.0 is a fully 32-bit development system for Windows 95 and NT 3.51. Two of the major new features in Visual Basic 4.0 are OLE automation objects and new data access features. In the fall of 1996, Esri released its first OLE product, MapObjects Version 1.0, which comprises 35 objects. These OLE objects are for use in object-oriented programming environments such as Visual Basic 4.0, Delphi 2.0, and PowerBuilder. So far, the combination of Visual Basic (VB) and MapObjects has been regarded as a good solution for mapping application development. Compared with other mapping applications developed with Arc Macro Language or Avenue, applications developed with Visual Basic and MapObjects have some big advantages. First, it is easier to build programs with VB and MapObjects. The developers can apply nearly any OLE automation objects provided by Microsoft or other third parties into the
applications. Second, the applications will have a small memory footprint. VB EXE files consume a small or modest portion of the system's memory. Third, the map from MapObjects will draw much faster than other Windows mapping software, since MapObjects is built directly on the Microsoft Foundation Class (MFC). Another important advantage is that with VB Database Jet Engine the application can handle large databases and perform queries and searches extremely fast. At Psomas and Associates, several applications have been developed using Visual Basic and MapObjects. These applications are for the City of Los Angeles Storm Water Management Division. Job efficiency has been improved and response time has been shortened by the implementation of these applications. In this paper, using the "Flood Plain GIS" application as an example, several VB and MapObjects technical issues for developing mapping applications will be explored. The OLE, Database Jet Engine, and spatial functions of MapObjects will be discussed in
detail.
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