MGMT 1000 Lecture Notes - Lecture 13: Programming Language
MGMT 1000 Tutorial 13 Notes –Lists of Procedures
Introduction
• A page description is a list of procedures and statements that describe each of the
objects on a page.
• PostScript embeds page descriptions within a programming language.
• Thus, an image consists of a program written in the PostScript language.
• The programming language is stored in ASCII or Unicode text form.
• Thus, PostScript files can be stored and transmitted as any other text file.
• An interpreter program in the computer or output device reads the PostScript language
statements and uses them to create pages that can then be printed or displayed.
• The interpreter produces an image that is the same, regardless of the device it is
displayed or printed on.
• Compensation for differences in device resolution and pixel shape is built into the
interpreter.
• PostScript provides a large library of functions that facilitate every aspect of an object-
based image.
• There are functions that draw straight lines, Bezier curves, and arcs of a circle, functions
that join simple objects into more complex ones, translate an object to a different
location on the page, scale or distort an object, rotate an object, and create the mirror
image of an object
• Functions that fill an object with a pattern, or adjust the width and color of a line.
• There are methods for building and calling procedures, and IF-THEN-ELSE and loop
programming structures.
• The list goes on and on.
• A simple program that draws a pair of shaded and concentric circles within a rectangle
in the middle of an 81/2 × 11-inch page is shown.
• This example shows a number of features of the language.
• The page is laid out as an X, Y grid, with the origin at the lower left corner.
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