SHAPE - A UNIFYING CONCEPT IN DOCUMENT LAYOUT

Abstract

Text objects have traditionally been constrained to be rectangular, a constraint inherited by modern computer document preparation systems. However, a variety of tasks in document formatting benefit from a more general notion of shape. This paper describes such a representation, suitable for graphic composition at both low and high levels of document layout. Intermediate in generality and complexity between rectangles and arbitrary polygons, it comprises separate left and right margin functions composed piecewise of linear segments. Such shapes can be compared, conbined, modified and generated using simple, economical algorithms. This notion of shape appears to provide the correct level of abstraction for elegant solutions to several knotty problems in existing systems. Software methods making use of shape have been implemented in JOT [Bonham 1985], an interactive documentation system under development as part of the University of Calgary JADE project [Witten et al 1983].