Java Reference
In-Depth Information
Chapter 25
Introducing Computer Graphics
Developing Graphical Applications
The programs developed so far provide output in text form only. Because of
its simplicity, this approach is useful when developing console-based appli-
cations that communicate with the user with simple text commands and do
not require graphics. However, text-based programs are almost an anachro-
nism, since most programs developed today communicate with the user by
means of graphics devices, such as the mouse, and are capable of output-
ting graphics.
In this chapter we provide a brief overview of computer graphics.
Graphics programming is a complex and elaborate subject, but elemen-
tary graphics in Java are not difficult.
Origin of Computer Graphics
During the late 1950s IBM and other companies invented and developed
several technologies that simplified computer use and programming. Ori-
ginally, computer input and output consisted of punched cards and paper
tape. The introduction of teletype machines (called TTYs) as an input and
output device was a major advance. A TTY has a typewriter-like keyboard
and produces a paper printout as well as a strip of paper or mylar tape in
which data is encoded in rows of punched holes. These tapes provide a con-
venient way for transferring data and programs from the TTY into the com-
puter.
Soon thereafter the Cathode Ray Tube, already in use in commercial
television, was adapted to displaying computer data. At first it was re-
