Computer display of characters

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This paper describes a general and flexible character generator which is capable of producing virtually an unlimited number of character fonts. To demonstrate this flexibility, eight different fonts, ranging from Roman letters and symbols, double line letters, APL characters etc. to a Devanagari script have been generated. These fonts have been chosen to see how characters with wide ranging requirements can be generated. For example, the Devanagari script requires combinations of different characters to produce various symbols; in fact, each of the basic 35 letters of this script can be combined in 12 different ways. This involves superimposing more than one character. Each of the fonts can be manipulated in a variety of different ways. The user can display a desired character string, with specified height and width, anywhere on the display device with any inclination, each character in the string having a desired orientation. Moreover, various other transformations, such as stretch, fall and skew, can be applied to the string. Interesting results are obtained by applying combinations of these transformations to a string. Mathematical formulae for all the transformations are derived and the results are included. The system is described both from the user's as well as system programmer's point of view. A generalized data structure is designed to define any font; the complete details of the data structure are given. Characters containing intricate details can be generated within the scope of the data structure. Several examples illustrating the ease of use and the flexibility of the system are given. Programmed in a device independent graphics environment, this facility can be used even by a novice FORTRAN programmer. Keywords: Character generation, computer graphics, multiple fonts, transformation of characters