On the Generalized Box-Drawing of Trees —Survey and New Technology—

This paper is on the aesthetic layout of n-ary trees with nodes of variable size, also referred to as generalized box-drawing. For this layout problem a few algorithms have been proposed, which differ in their runtime performance and the attained aesthetic criteria. We introduce a new approach to this layout problem, which is interesting because of both its simplicity and elegance, and which employs the following piggy-back metaphor: The original box-drawing problem, Π , is topologically reformulated as a layout problem with uniform node size, resulting in a new drawing problem Π ′, which then is handled by the best tree layout algorithm for uniform node size developed so far. The reformulation step can be done in linear time in the number of nodes of the original tree, resulting in an overall linear time complexity. Compared to the existing approaches our approach fulfills more aesthetic criteria; experiments have also shown its efficiency in complex layout settings.