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daVinci API - Introduction

After using daVinci for a while, you might wish to have a similar user interface for the application program you have developed. Until now, you have been afraid of the cost of such an expensive implementation. But imagine how the user will be able to handle your complicated graph data structure by easily browsing an elegant and intuitive graph drawing of high quality. How about controlling your application by simply clicking on nodes and edges in a graph visualization? This is the typical szenario where you want to start using the API to plug daVinci on top of your application.

daVinci does not control the structure of a displayed graph. It is a pure visualization system and is even not able to alter the graph structure on its own. So unlike usual graph editors (which may take control on the development of a graph by removing or adding nodes and edges without any notion about the specific underlying semantic), daVinci let your application decide what operations need to be applied when nodes and edges are clicked or menus and icons are selected.

The basic philosophy of daVinci is to have two levels of responsibility:

The visualization layer (daVinci), responsible for graphical representation, but without permission to manipulate the graph structure on its own.
The application layer (some application program connected to the API) which decides what to do if an operation should be applied that modifies the structure of a graph.

The following figure illustrates the data flow between an application program and daVinci:

An application is connected with daVinci's API by using two communication channels: One to send commands (e.g. graphs) and one to receive the answers (e.g. events). With API commands, the application is able to send graphs for visualization and attach its own dialog elements (i.e. menus and icons) to the daVinci user interface. Afterwards, the application will wait for answers from daVinci. These are events triggered by user interaction in daVinci's graph visualization windows. Based on these event, for example a particular menu selection in the context of a previous node selection, the application can decide what operations need to be applied on its own local graph data structure, for example deleting the specific node if the semantic of the selected menu is "removal". After modifying its own data structure, the application has to sent the new graph (or an increment) to daVinci to update the graph visualization.

daVinci V2.1 Online Documentation - Page update: June 15, 1998