User-interface devices for rapid and exact number specification
Ari Rappoport, Maarten van Emmerik · ACM Transactions on Graphics · 1993
Graphics and geometric modeling applications must provide the user with convenient methods of specifying integer and real numbers.These numbers can be coordinates of an object in some coordinate system, parameters for various geometric transformations, color and material values, and so on.A good user-interface device (UID) for number specification is an essential ingredient in any user-interface toolkit for geometric applications.Application requirements for number specification are diverse: single-and multidigit numbers, numbers in a bounded or infinite range, and both integer and real numbers.Different number bases may be desired.A desirable feature of any number specification device is the ability to define a grid and to snap the number to the nearest grid point.This is widely recognized in 2-D drawing systems and is beginning to be in 3-D systems [Bier 1990].Numbers or mouse locations are adjusted according to the current grid before being assigned to application objects.It would be intuitive to let the user control the grid parameters in the same context in which the number itself is manipulated.Current user-interface toolkits (e.g., Motif7 provide a very limited set of UIDS for number specification; usually only a text UID and a slider UID are Part of this work was done while the authors were with the Interactive Geometric Modeling group at the IBM T.