Parsing Adjacency Languages for Calligraphic Interfaces

Integration of pen input into interactive environments holds the promise of gains in user friendliness and more natural interaction styles than present direct manipulation tools can provide, since handwritten gestures and pen strokes offer more expressive power than the keyboard or mouse. However, penbased applications have yet to enjoy widespread acceptance, because pen data are diffcult to analyze due to noise, user variations and imprecise meaning. Calligraphic interfaces is a term we have coined to designate a class of pen based user interfaces in which handsketching or drawing serves as the main organizational metaphor as opposed to the point-and-click desktop metaphor commonly employed in current graphical user interfaces. Our study of calligraphic interfaces extends previous research in formal visual languages, syntactic pattern recognition, and user interface design. Our adjacency-driven parsing approach improves on previous research by using adjacency-constraining relations to prune the search space during intermediate analysis steps thereby yielding gains in asymptotic complexity.