DiaGen: a generator for diagram editors providing direct manipulation and execution of diagrams

Diagrams (e.g., flowcharts, trees for hierarchical structures, or graphs for finite state machines) are often needed as part of visual language systems and advanced user interfaces, and are frequently application specific. The implementation of editors for diagrams should be supported by a tool and based on a formal model. This paper gives an overview of DiaGen, a generator for diagram editors. An editor for a certain kind of diagram is generated from a specification, which includes a hypergraph grammar to describe the structure of diagrams. The user of a diagram editor does not have to be concerned with the grammar, but can manipulate diagrams very conveniently by direct manipulation. As an additional and important feature in the context of visual languages, editors generated by DiaGen cannot only be used for editing, but also for executing, i.e., animating diagrams