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Annotated edit history of PostScript version 15 showing authors affecting page license. View with all changes included.
Rev Author # Line
13 LawrenceDoliveiro 1 !!! YOU POSTSCRIPT LOVE {HONK} IF
2
15 LawrenceDoliveiro 3 A stack-based ProgrammingLanguage that resembles [Forth], but mixes in some functional programming principles to allow a considerably higher level of abstraction. Although a complete, general purpose language, it was developed for typesetting and is accompanied by a complex, powerful graphical model. Adobe Systems, the creators of ~PostScript, also produced a version for use on-screen, called Display ~PostScript, but that was never very popular, and was eventually abandoned.
10 AristotlePagaltzis 4
5 PostScript programs come in __.ps__ files. GhostScript is a [Free] software-only implementation of the language and graphics model, allowing users to view such files onscreen as well as send them to cheap printers that do not understand PostScript natively. PostScript is also the language used at the core of [PDF].
6
7 The [Printing HOWTO | http://www.tldp.org/HOWTO/Printing-HOWTO/] explains why PostScript happened to become so well established.
8
9 Here's a simple example of what PostScript code looks like:
10
11 ----
12
13 <verbatim>
14 %!PS-Adobe-2.0
15 %%BoundingBox: 0 0 400 400
16 %%Pages: 1
17 %%EndComments
18
19 % any line starting with % is treated as a comment. "%!" as the first two
20 % bytes of the file is the "magic marker" that implies postscript.
21
22 % Exception...
23 % need postscript version 2 or later to understand the above-style
24 % "special" comments starting with "%%". Also can use like that per-page
25
26 %%Page: 1 1
27
28 % disclaimer: the commands and examples given here aren't taken from a
29 % reference manual or anything, so some of the comments might be wrong or
30 % mis-understand what is actually happening...
31
32 save % save the current colour, scale factor, etc variables to the stack
33
34 % set the active colour to red (this is an R G B setting, between 0 and 1)
35 1.0 0 0 setrgbcolor
36
37 % scale is global... if you double the scale, you need to halve it again
38 % later, unless you use save and restore...
39
40 2 1 scale % set the scaling factor to 2x for x and 1x (ie normal) for y
41
42 % draw a circle (well, it would be a circle if scaling was 1x)
43
44 % x-origin y-origin radius startangle endangle arc (before scaling)
45
46 100 100 50 0 360 arc % draws an arc (might be invisible)
47
48 fill % fills the previous object with the active colour
49
50 restore % go back to colour, scale, etc of the last save
51
52 % create some constants
53 /x 100 def
54 /y 100 def
55 /radius 50 def
56
57 % draw a circle using the saved state
58 x y radius 0 360 arc fill
59
60
61 % make some alias commands
62 /black {0 0 0 setrgbcolor} bind def
63 /blue {0 0 1 setrgbcolor} bind def
64
65 % use them
66 blue
67
68 % move the "cursor"
69 100 300 moveto
70
71 % print some text
72 % before we can print text, we need to select the active font.
73 /Times-Roman findfont % font name
74 12 scalefont % font size
75 setfont % make that font the active font
76
77 (Hello. This is blue text) show
78
79 black
80 100 250 moveto ( You need to escape \( and \) as \\\( and \\\)) show
81
82 % the "translate" command draws everything offset by this x and y,
83 % save and restore this - takes effect until the next translate or restore
84 % 200 0 translate % causes everything from here-on to be drawn
85 % 200 pts to the right
86
87
88 50 200 moveto % set current position
89 3 -5 (diagonal) ashow
90
91 % print out the memory usage info
92
93 /Times-Roman-Bold findfont % choose font
94 15 scalefont % font size
95 setfont % make active
96
97 200 225 moveto (Memory Info:) show
98
99 % print out information about the memory usage
100 vmstatus % ps function that puts 3 numbers on the stack...
101 % to be honest, I'm not sure what the numbers are. I suspect
102 % the 2nd is the mem used, and the 3rd is mem allocated. But ghostscript
103 % can dynamically increase the avail mem, so it isn't really a very useful
104 % number in most cases. If you send this file to a postscript printer it
105 % might actually mean something...
106 %
107 3 1 roll % take top value on stack and put it 3rd
108 exch % swap the top 2 values
109 %%% - now have reversed the order of the 3 numbers from vmstatus
110 200 204 moveto
111
112 /Times-Roman findfont 12 scalefont setfont
113 (Min(?): ) show
114 10 string % create a 10-byte string
115 cvs % fill the string with the previous number on the stack
116 show ( bytes) show
117 200 192 moveto
118 (Used: ) show
119 10 string cvs show ( bytes) show
120 200 180 moveto
121 (Max: ) show 10 string cvs show ( bytes) show
122
123 %% draw a small irregular polygon
124 0 setlinewidth %
125 newpath
126 260 300 moveto
127 270 315 lineto
128 300 315 lineto
129 310 280 lineto
130 300 260 lineto
131 closepath % back to the origin
132 1 0 1 setrgbcolor % red + blue = purple
133 fill
134
135 % print something to gv's pop-up informative window, or stdout for gs
136 (Example simple postscript commands\n) print
137 flush % cause it to be sent (from buffered)
138
139 %%EndPage
140
141 showpage % render the page
142
143 %%EOF
144
145 </verbatim>
146
147 ----
148 CategoryProgrammingLanguages, CategorySpecialPurposeProgrammingLanguages