Generating a Visual System with Soft Layout Constraints

We developed a visual system generator called “Rainbow” which can handle layout constraints. The system can interactively layout figures while parsing them and make the parsed figures more understandable. Rainbow can deal with “soft layout constraints.” Soft layout constraints automatically layout entire figures by using graph drawing algorithms. Soft layout constraints are more flexible than constraints that determine coordinates and distances between figure elements. We have implemented three kinds of soft layout constraints: the spring model constraint, magnetic spring model constraint, and tree structure constraint. We use the spring model constraint to layout an undirected graph. The magnetic spring model constraint is used to layout a directed/undirected graph by controlling the orientation of an edge. The tree structure constraint is used to layout a graph in a tree structure. We will show two examples, “organization diagrams” and “E-R diagrams.”