doc/help/spec-postscript.html

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  CUPS PostScript file specification for CUPS.

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<H1 CLASS="title">Generating PostScript for CUPS</H1>

<h2 class='title'><a name='INTRODUCTION'>Introduction</a></h2>

<p>This document describes how to generate PostScript output for
CUPS and is largely based on the <a
href="http://partners.adobe.com/public/developer/en/ps/5001.DSC_Spec.pdf">
Adobe TechNote #5001: PostScript Language Document Structuring
Conventions Specification Version 3.0</a>. While CUPS can
generally print any PostScript file, following the rules in the
Adobe TechNote and this document will ensure that your PostScript
output will work reliably.</p>

<blockquote><b>Note:</b> While PostScript is currently the
de-facto standard print job file format/language for UNIX-based
applications, it is slowly being phased out in favor of Adobe's
Portable Document Format ("PDF") which offers many advantages
over PostScript. macOS uses PDF as the primary print job file
format and Linux is making the transition. Both PostScript and
PDF are complex formats, and we highly recommend using high-level
toolkits whenever possible to create your print jobs.</blockquote>

<h3>Anatomy of a PostScript File</h3>

<p>PostScript files are ASCII text files starting with a header
line (<tt>%!PS-Adobe-3.0</tt>) followed by a combination of
comment lines starting with the percent sign (<tt>%</tt>) and
PostScript code lines. The lines themselves should not exceed 255
characters to conform to the DSC. The following short PostScript
file produces a box with a smiley face in it:</p>

<pre class="command">
%!PS-Adobe-3.0
%%BoundingBox: 36 36 576 756
%%Pages: 1
%%LanguageLevel: 2
%%EndComments
%%BeginSetup
% this is where fonts would be embedded
%%EndSetup
%%Page: (1) 1
%%BeginPageSetup
% this is where page-specific features would be specified
%%EndPageSetup
% Draw a black box around the page
0 setgray
1 setlinewidth
36 36 540 720 rectstroke

% Draw a two inch blue circle in the middle of the page
0 0 1 setrgbcolor
306 396 144 0 360 arc closepath fill

% Draw two half inch yellow circles for eyes
1 1 0 setrgbcolor
252 432 36 0 360 arc closepath fill
360 432 36 0 360 arc closepath fill

% Draw the smile
1 setlinecap
18 setlinewidth
306 396 99 200 340 arc stroke

% Print it!
showpage
%%EOF
</pre>

<div class="figure"><table summary="Sample PostScript File Output">
<caption>Figure 1: <a name="FIGURE_1">Sample PostScript File Output</a></caption>
<tr><td align="center"><img src="../images/smiley.jpg"
width="445" height="570" alt="Sample PostScript File Output"></td></tr>
</table></div>


<h2><a name='OPTIONS'>Embedding Printer Options</a></h2>

<p>There are two main strategies for embedding printer options in PostScript
files. The first is to list CUPS options using the <code>%cupsJobTicket</code>
comment:</p>

<pre>
%!PS-Adobe-3.0
%cupsJobTicket: media=A4 sides=two-sided-long-edge
%cupsJobTicket: PrinterOption=foo PrinterOption2=bar
...
%%EndComments
</pre>

<p>CUPS options apply to the entire job. To apply options to individual pages,
use the <code>%%IncludeFeature</code> comment instead:</p>

<pre>
%%Page: label 123
%%BeginPageSetup
%%IncludeFeature: *PageSize A4
%%IncludeFeature: *PrinterOption Foo
%%IncludeFeature: *PrinterOption2 Bar
%%EndPageSetup
...
</pre>


<h2><a name='FONTS'>Embedding Fonts and Text</a></h2>

<p>Always embed the fonts used by your print job, and for best performance
embed the fonts and character encodings in the setup section of the PostScript
file. Type 1 and Type 3 fonts are supported by all PostScript printers, while
Type 42 (TrueType) and CID fonts are supported by most level 2 and all level 3
PostScript printers. Binary font files should always be converted to the
corresponding ASCII (hex) encoding to avoid problems when printing over
interfaces that do not support binary PostScript.</p>


<h2><a name='IMAGES'>Embedding Images</a></h2>

<p>The <code>image</code> operator should be used to embed images in PostScript
files. Always use ASCII hex or Base-85 encoding for the image data to avoid
problems when printing over interfaces that do not support binary PostScript.
In most cases, the Base-85 encoding and compression filters can be used to
embed images with very little, if any, increase in data size.</p>

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