Program graph visualization

Although there are many algorithms to draw hierarchical structures such as directed graphs and trees none specifically treat the problem of visualizing program graphs, This paper presents an algorithm and the underlying tool - ViewGraph - designed to visualize program graphs, The algorithm Is divided in two parts: (1) determine node positions, and (2) assign routes to branches, The first part has three steps: level assignment, scope and position calculation, A modified algorithm used to assign levels to nodes in a tree Is used to find Y coordinates; a concept called scope is used to define X coordinates,Scope is a prediction of the space required by a node and its descendants, A search on the available positions left by the placement of nodes is performed to route branches, A set of aesthetic aspects meant to help the development of program graph visualization algorithms is also proposed, The algorithm runs in an acceptable time making it useful even for interactive applications. (C) 1997 by John Wiley & Sons, Ltd.27111245126