An effective layout adaptation technique for a graphical modeling tool

Editing graphic models always entails layout problems. Inserting and deleting items requires tedious manual work for shifting existing items and rearranging the diagram layout. Hence, techniques that automatically expand a diagram when space is required for insertion and contract it when free space becomes available are highly desirable. Existing layout generation algorithms are no good solution for that problem: they may completely rearrange a diagram after an editing operation, while users want to preserve the overall visual appearance of a diagram. We have developed a technique which automatically expands or contracts a diagram layout when items are inserted or removed while preserving its overall shape, i.e. the positions of the items relative to each other Our technique has been implemented in a prototype tool. We are using it not just for simplifying editing, but primarily for implementing an aspect-oriented visualization concept.