Auto-completion for diagram editors based on graph grammars

Graphs are known to be well-suited as an intermediate data structure in diagram editors. The syntax of a particular visual language can be defined by means of a graph grammar. In recent work we have proposed approaches to graph completion: given a possibly ldquoincompleterdquo graph, this graph is modified in such a way that the resulting graph is a member of the grammarpsilas language. In this paper we describe how graph completion can be used to realize diagram completion, an important requirement for the realization of content assist in diagram editors. With our approach, the advantages of free-hand and structured editing can be effectively combined: drawing of diagrams with maximal freedom and powerful guidance whenever needed.