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Overview
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What is PostScript?
Types
Language Concepts
Control Operators
Examples
What is PostScript
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page description language :
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PostScript is a programming language optimized
for printing graphics and text
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It was introduced by Adobe in 1985
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The main purpose of PostScript was to provide a
convenient language in which to describe images
in a device independent manner. This device
independence means that the image is described
without reference to any specific device features
(e.g. printer resolution)
Types
String:
 “This is a string” would be written as (This is a
string).
Express a string as hexadecimal codes in angle
brackets. “ABC” would be expressed as
<414243>.
Boolean
Real
Array
Types
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Arrays:
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One Dimensional
Object of different types in an array
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/arrayName [ 12 (Twelve) True] def
/arrayName [ 1 2 4 add] def
/arrayName 10 array
Store and Fetch array elements: put, get
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/anArray 10 array def
anArray 8 (language) put
anArray 8 get
Language Concepts
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Variable: /varName value def
Path: A path is a collection of (possibly disjoint) line segments
and curves arranged on the page.
 newpath
144 72 moveto
144 432 linto
stroke
showpage
Dictionary: is a table that associates pairs of objects
<Key, Value>
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System Dictionary : operator , action
User Dictionary : /var1Name Value def
Language Concepts
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Procedures:
 /inch {72 mul} def
Stack:
 Graphic Stack
 Operand Stack (clear, dup, pop, roll, pstack)
 Dictionary Stack
Operator: Every command in PostScript is an
operator: add, mul, findfont, moveto ...
Programming in PostScript
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Postfix Notation in
PostScript : One must
first place the operands
on stack and then call the
operator.
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5+27
5 27 add
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8 –7 * 3
8 7 3 mul sub
7 3 mul 8 exch sub
Control Operators
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Conditional:
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Comparisons:
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Logical Operator:
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And , or, not, xor
bool { op } if
bool {op1} {op2} ifelse
Control Operator
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Loops:
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Repeat:
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For:
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Iteration { loop_body_expression} repeat
Loop_counter_init_value increment_value {op} for
{ op }loop : end with “exit”
AnArray {op} forall
/Times-Italic findfont 30 scalefont setfont
/printZip
{ 0 0 moveto (Zip) show} def
320 400 translate
.95 -.05 0
% start incr. end
{setgray printZip -1 .5 translate } for
1 setgray printZip
showpage
/starside
{ 72 0 lineto
currentpoint translate
-144 rotate } def
/star
{ moveto
currentpoint translate
4 {starside} repeat
closepath
gsave
.5 setgray fill
grestore
stroke } def
200 200 star
%add line to path
%move origin
%rotate coord. sys.
%stack: x y
Refrences
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http://www-cdf.fnal.gov/offline/PostScript/BLUEBOOK.PDF
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http://www.tailrecursive.org/postscript/postscript.html