A Tablet Input Facility for an Interactive Graphics System

Abstract

Effective man-machine communication in an interactive graphics environment requires a natural and convenient way for the on-line user to input information and issue commands to the computer . Several applications have been described in which such an interface has been achieved by allowing the user to draw symbols on a tablet. In order to make this mode of interaction generally available to users of the TX-2 graphics facility,4 we have augmented the TX-2 graphics programming language LEAP 6 with constructs for handling tablet input and interfacing with a user-trainable symbol recognizer. These extensions to LEAP have made the incorporation of a flexible input technique into a graphics application program as straightforward for the programmer as typewriter input. Experimentation with the man-machine interface has thereby been greatly simplified , resulting in the faster development of useful graphics applications . This paper illustrates an application which uses the symbol recognition facility, and describes the language extensions through which the interactive aspects of such an application a re implemented