A device independent computer plotting system
Almost every computing centre has a variety of plotting devices. Software available for these plotting devices is often device dependent. As a result, in order to switch from one plotting device to another, the user has to make several programming changes. This procedure is error prone and time consuming. This paper describes a device independent computer plotting system which is based on several routines accessible from FORTRAN IV. The transition from one plotting device to another is completely transparent to the user of this system. The paper begins with the descriptions of various plotting devices and plotting modes. This is followed by an overview which consists of an example and functional descriptions of all the routines. The system interface and the basis on which the device independence is achieved are discussed in the later portion of the paper. Finally, the data structures used in the offline mode of plotting, the algorithms used in the various driver routines and the mechanism used to account for the plotting resources are presented. The interface for adding a new plotting device has been formalized and defined. The system is open ended and can be expanded in the device independent as well as the device dependent area.