Research On Data Management Of Vector Graphics Editor Based On COM

The Vector Graphics Editor (VGE) provides graphics editing environment independent of other practical application systems. It is constructed with Component Object Model (COM). Based on the idea of component-based development, every function module of the VGE system is developed solely as a component. All components transmit data and communicate each other through the COM interface.Scalable Vector Graphics (SVG) is used in the system in order to store graphics data efficiently. According to the characteristics of SVG, graphics data description model and graphics database based on extensible markup language (XML) can be built. SVG is an open text-based scalable vector graphics standard developed by W3C. It has a widely applied foreground because its storage capacity is small and it is prone to release graphics data in the network.Almost all graphics data have very complicated structure. Therefore, user's workload can be greatly reduced if a rational data model is built. In the VGE system, object model is adopted to administer graphics data. Within the model, Graphics object is the basic unit of graphics data. Graphics element is a special graphics object, which includes a reusable graphics block and denotes physical equipment. Data description model of the graphics element is composed of geometrical shape, application property and alternating event. Furthermore, dada storage structure is implement by a link list. This list includes all graphics object of a set of graphics and can be used in the undo/redo function at the same time. The design of graphics database is a 3-tier structure. Using storage strategy of XML-enable database, methods mapping document type definition to relational table can be set up. Accordingly, methods of storage and query of the graphics database come true.By combining COM with SVG, The system is reusable, expandable, transplantable and easily to be maintained. Moreover, because all graphics data are uniformly administered by a graphics database, all kinds of graphics can be created easily and conveniently. Meanwhile, application range of the system is largely extended.