Path: utzoo!mnetor!uunet!husc6!endor!olson
From: olson@endor.harvard.edu (Eric K. Olson)
Newsgroups: comp.lang.postscript
Subject: Re: Encapsulated PostScript
Message-ID: <3608@husc6.harvard.edu>
Date: 18 Dec 87 19:19:07 GMT
References: <488@tetons.UUCP>
Sender: news@husc6.harvard.edu
Reply-To: olson@endor.UUCP (Eric K. Olson)
Organization: Lexington Software Design
Lines: 168

In a recent article Greg Darnell writes:
>
>Can anyone tell me what "Encapsulated" PostScript is?
...
>Any information on the definition, an example or a reference would
>be greatly appreciated.  Thanks.

Description:
A set of commenting conventions and additional rules for Postscript
procedures.  Comments can be figured out from the following example.
Other rules include:  Don't use banddevice, copypage, erasepage, exitserver
framedevice grestoreall, initclip, initgraphics, initmatrix, legal, letter, 
note, nulldevice, quit, renderbands, setpageparams, setdevice, setsccbatch,
setmatrix, or stop.  Showpage is permitted, but will be disabled by the
importing application.  All stacks should end as they started.  Do not
overnest save/restore and gsave/grestore, since the importing file might
already have used a lot of the (limited) nesting levels.

EPS files also usually have an optional low-resolution picture in the Resource
Fork if they are on a Macintosh.  IBM EPS files have a small header:

long	'EPSF'
long	byte position in file for PS start
long	byte length of PS
long	byte position in file for MetaFile screen representation
long	byte length of screen representation
long	byte position in file of TIFF screen representation
long	byte length of TIFF
short	checksum (XOR of bytes 0-27 in file; ignored if FFFF)

position and length for MetaFile and TIFF may be 0 and will be ignored.

Reference:
AltSys Corporation
Attn: Jim Von Ehr
720 Ave. F, Suite 108, Dept. EPS
Plano, TX 75074
(214) 424-4888
MCI: ALTSYS

Example of Encapsulated Postscript:
Taken from Adobe Illustrator 1.1; draws a box.

%!PS-Adobe-2.0 EPSF-1.2
%%Creator:Adobe Illustrator(TM) 1.1 M00004385N
%%For:Eric K. Olson Pixelogic, Inc.
%%Title:Box.epsf.mac
%%CreationDate:12/18/87 2:09 PM
%%DocumentProcSets:Adobe_Illustrator_1.1 0 0
%%DocumentSuppliedProcSets:Adobe_Illustrator_1.1 0 0
%%DocumentFonts:Courier
%%BoundingBox:23 -138 144 -21
%%TemplateBox:288 -360 288 -360
%%EndComments
%%BeginProcSet:Adobe_Illustrator_1.1 0 0
% Copyright (C) 1987 Adobe Systems Incorporated.
% All Rights Reserved.
% Adobe Illustrator is a trademark of Adobe Systems Incorporated.
/Adobe_Illustrator_1.1 dup 100 dict def load begin
/Version 0 def
/Revision 0 def
% definition operators
/bdef {bind def} bind def
/ldef {load def} bdef
/xdef {exch def} bdef
% graphic state operators
/_K {3 index add neg dup 0 lt {pop 0} if 3 1 roll} bdef
/_k /setcmybcolor where 
{/setcmybcolor get} {{1 sub 4 1 roll _K _K _K setrgbcolor pop} bind} ifelse def
/g {/_b xdef /p {_b setgray} def} bdef
/G {/_B xdef /P {_B setgray} def} bdef
/k {/_b xdef /_y xdef /_m xdef /_c xdef /p {_c _m _y _b _k} def} bdef
/K {/_B xdef /_Y xdef /_M xdef /_C xdef /P {_C _M _Y _B _k} def} bdef
/d /setdash ldef
/_i currentflat def
/i {dup 0 eq {pop _i} if setflat} bdef
/j /setlinejoin ldef
/J /setlinecap ldef
/M /setmiterlimit ldef
/w /setlinewidth ldef
% path construction operators
/_R {.25 sub round .25 add} bdef
/_r {transform _R exch _R exch itransform} bdef
/c {_r curveto} bdef
/C /c ldef
/v {currentpoint 6 2 roll _r curveto} bdef
/V /v ldef
/y {_r 2 copy curveto} bdef
/Y /y ldef
/l {_r lineto} bdef
/L /l ldef
/m {_r moveto} bdef
% error operators
/_e [] def
/_E {_e length 0 ne {gsave 0 g 0 G 0 i 0 J 0 j 1 w 10 M [] 0 d
/Courier 20 0 0 1 z [0.966 0.259 -0.259 0.966
_e 0 get _e 2 get add 2 div _e 1 get _e 3 get add 2 div] e _f t T grestore} if} bdef
/_fill {{fill} stopped
{/_e [pathbbox] def /_f (ERROR: can't fill, increase flatness) def n _E} if} bdef
/_stroke {{stroke} stopped
{/_e [pathbbox] def /_f (ERROR: can't stroke, increase flatness) def n _E} if} bdef
% path painting operators
/n /newpath ldef
/N /n ldef
/F {p _fill} bdef
/f {closepath F} bdef
/S {P _stroke} bdef
/s {closepath S} bdef
/B {gsave F grestore S} bdef
/b {closepath B} bdef
% text block construction and painting operators
/_s /ashow ldef
/_S {(?) exch {2 copy 0 exch put pop dup false charpath currentpoint _g setmatrix
_stroke _G setmatrix moveto 3 copy pop rmoveto} forall pop pop pop n} bdef
/_A {_a moveto _t exch 0 exch} bdef
/_L {0 _l neg translate _G currentmatrix pop} bdef
/_w {dup stringwidth exch 3 -1 roll length 1 sub _t mul add exch} bdef
/_z [{0 0} bind {dup _w exch neg 2 div exch neg 2 div} bind {dup _w exch neg exch neg} bind] def
/z {_z exch get /_a xdef /_t xdef /_l xdef exch findfont exch scalefont setfont} bdef
/_g matrix def
/_G matrix def
/_D {_g currentmatrix pop gsave concat _G currentmatrix pop} bdef
/e {_D p /t {_A _s _L} def} bdef
/r {_D P /t {_A _S _L} def} bdef
/a {_D /t {dup p _A _s P _A _S _L} def} bdef
/o {_D /t {pop _L} def} bdef
/T {grestore} bdef
% group construction operators
/u {} bdef
/U {} bdef
% font construction operators
/Z {findfont begin currentdict dup length dict begin
{1 index /FID ne {def} {pop pop} ifelse} forall /FontName exch def dup length 0 ne
{/Encoding Encoding 256 array copy def 0 exch {dup type /nametype eq
{Encoding 2 index 2 index put pop 1 add} {exch pop} ifelse} forall} if pop
currentdict dup end end /FontName get exch definefont pop} bdef
end
%%EndProcSet
%%EndProlog
%%BeginSetup
Adobe_Illustrator_1.1 begin
n
%%EndSetup
u
0 g
0 G
0 i
0 J
0 j
1 w
10 M
[]0 d
%%Note:
143 -137 m
143 -22 L
24 -22 L
24 -137 L
143 -137 L
f
83.5 -79.5 m
F
U
%%Trailer
_E end

                      (defun maybe (x) (maybe (not x)))
Eric K. Olson     olson@endor.harvard.edu     harvard!endor!olson     D0760
   (Name)                (ArpaNet)                 (UseNet)        (AppleLink)