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453<!--
454  PostScript printer driver documentation for CUPS.
455
456  Copyright © 2007-2012 by Apple Inc.
457  Copyright © 1997-2007 by Easy Software Products.
458
459  Licensed under Apache License v2.0.  See the file "LICENSE" for more
460  information.
461-->
462
463<h1 class='title'>Developing PostScript Printer Drivers</h1>
464
465<p>This document describes how to develop printer drivers for PostScript printers. Topics include: <a href='#BASICS'>printer driver basics</a>, <a href='#CREATE'>creating new PPD files</a>, <a href='#IMPORT'>importing existing PPD files</a>, <a href='#FILTERS'>using custom filters</a>, <a href='#COLOR'>implementing color management</a>, and <a href='#MACOSX'>adding macOS features</a>.</p>
466
467<div class='summary'><table summary='General Information'>
468<tbody>
469<tr>
470	<th>See Also</th>
471	<td>Programming: <a href='raster-driver.html'>Developing Raster Printer Drivers</a><br>
472	Programming: <a href='api-filter.html'>Filter and Backend Programming</a><br>
473	Programming: <a href='ppd-compiler.html'>Introduction to the PPD Compiler</a><br>
474	Programming: <a href='api-raster.html'>Raster API</a><br>
475	References: <a href='ref-ppdcfile.html'>PPD Compiler Driver Information File Reference</a><br>
476	Specifications: <a href='spec-ppd.html'>CUPS PPD Extensions</a></td>
477</tr>
478</tbody>
479</table></div>
480    <div class="contents">
481      <h2 class="title">Contents</h2>
482      <ul class="contents">
483        <li><a href="#BASICS">Printer Driver Basics</a></li>
484        <li><a href="#CREATING">Creating New PPD Files</a><ul class="subcontents">
485          <li><a href="#IMPORT">Importing Existing PPD Files</a></li>
486        </ul></li>
487        <li><a href="#FILTERS">Using Custom Filters</a></li>
488        <li><a href="#COLOR">Implementing Color Management</a></li>
489        <li><a href="#MACOSX">Adding macOS Features</a></li>
490      </ul>
491    </div>
492    <div class="body">
493<h2 class='title'><a name='BASICS'>Printer Driver Basics</a></h2>
494
495<p>A CUPS PostScript printer driver consists of a PostScript Printer Description (PPD) file that describes the features and capabilities of the device, zero or more <em>filter</em> programs that prepare print data for the device, and zero or more support files for color management, online help, and so forth. The PPD file includes references to all of the filters and support files used by the driver.</p>
496
497<p>Every time a user prints something the scheduler program, <a href='man-cupsd.html'>cupsd(8)</a>, determines the format of the print job and the programs required to convert that job into something the printer understands. CUPS includes filter programs for many common formats, for example to convert Portable Document Format (PDF) files into device-independent PostScript, and then from device-independent PostScript to device-dependent PostScript. <a href='#FIGURE_1'>Figure 1</a> shows the data flow of a typical print job.</p>
498
499<div class='figure'><table summary='PostScript Filter Chain'>
500<caption>Figure 1: <a name='FIGURE_1'>PostScript Filter Chain</a></caption>
501<tr><td><img src='../images/cups-postscript-chain.png' width='700' height='150' alt='PostScript Filter Chain'></td></tr>
502</table></div>
503
504<p>The optional PostScript filter can be provided to add printer-specific commands to the PostScript output that cannot be represented in the PPD file or to reorganize the output for special printer features. Typically this is used to support advanced job management or finishing functions on the printer. CUPS includes a generic PostScript filter that handles all PPD-defined commands.</p>
505
506<p>The optional port monitor handles interface-specific protocol or encoding issues. For example, many PostScript printers support the Binary Communications Protocol (BCP) and Tagged Binary Communications Protocol (TBCP) to allow applications to print 8-bit ("binary") PostScript jobs. CUPS includes port monitors for BCP and TBCP, and you can supply your own port monitors as needed.</p>
507
508<p>The backend handles communications with the printer, sending print data from the last filter to the printer and relaying back-channel data from the printer to the upstream filters. CUPS includes backend programs for common direct-connect interfaces and network protocols, and you can provide your own backend to support custom interfaces and protocols.</p>
509
510<p>The scheduler also supports a special "command" file format for sending maintenance commands and status queries to a printer or printer driver. Command print jobs typically use a single command filter program defined in the PPD file to generate the appropriate printer commands and handle any responses from the printer. <a href='#FIGURE_2'>Figure 2</a> shows the data flow of a typical command job.</p>
511
512<div class='figure'><table summary='Command Filter Chain'>
513<caption>Figure 2: <a name='FIGURE_2'>Command Filter Chain</a></caption>
514<tr><td><img src='../images/cups-command-chain.png' width='575' height='150' alt='Command Filter Chain'></td></tr>
515</table></div>
516
517<p>PostScript printer drivers typically do not require their own command filter since CUPS includes a generic PostScript command filter that supports all of the standard functions using PPD-defined commands.</p>
518
519
520<h2 class='title'><a name='CREATING'>Creating New PPD Files</a></h2>
521
522<p>We recommend using the CUPS PPD compiler, <a href='man-ppdc.html'>ppdc(1)</a>, to create new PPD files since it manages many of the tedious (and error-prone!) details of paper sizes and localization for you. It also allows you to easily support multiple devices from a single source file. For more information see the "<a href='ppd-compiler.html'>Introduction to the PPD Compiler</a>" document. <a href='#LISTING_1'>Listing 1</a> shows a driver information file for a black-and-white PostScript printer.</p>
523
524<p class='example'>Listing 1: <a name='LISTING_1'>"examples/postscript.drv"</a></p>
525
526<pre class='example'>
527// Include standard font and media definitions
528<a href='ref-ppdcfile.html#_include'>#include</a> &lt;font.defs&gt;
529<a href='ref-ppdcfile.html#_include'>#include</a> &lt;media.defs&gt;
530
531// Specify this is a PostScript printer driver
532<a href='ref-ppdcfile.html#DriverType'>DriverType</a> ps
533
534// List the fonts that are supported, in this case all standard fonts
535<a href='ref-ppdcfile.html#Font'>Font</a> *
536
537// Manufacturer, model name, and version
538<a href='ref-ppdcfile.html#Manufacturer'>Manufacturer</a> "Foo"
539<a href='ref-ppdcfile.html#ModelName'>ModelName</a> "Foo LaserProofer 2000"
540<a href='ref-ppdcfile.html#Version'>Version</a> 1.0
541
542// PostScript printer attributes
543<a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
544<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
545<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
546<a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
547<a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
548<a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
549
550// Supported page sizes
551*<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Letter
552<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Legal
553<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> A4
554
555// Query command for page size
556<a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
557      save
558      currentpagedevice /PageSize get aload pop
559      2 copy gt {exch} if (Unknown)
560      23 dict
561              dup [612 792] (Letter) put
562              dup [612 1008] (Legal) put
563              dup [595 842] (A4) put
564              {exch aload pop 4 index sub abs 5 le exch
565               5 index sub abs 5 le and
566              {exch pop exit} {pop} ifelse
567      } bind forall = flush pop pop
568      restore"
569
570// Specify the name of the PPD file we want to generate
571<a href='ref-ppdcfile.html#PCFileName'>PCFileName</a> "fooproof.ppd"
572</pre>
573
574<h3>Required Attributes</h3>
575
576<p>PostScript drivers require the attributes listed in <a href='#TABLE_1'>Table 1</a>. If not specified, the defaults for CUPS drivers are used. A typical PostScript driver information file would include the following attributes:</p>
577
578<pre class='example'>
579<a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
580<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
581<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
582<a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
583<a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
584<a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
585</pre>
586
587<div class='table'><table summary='Required PostScript Printer Driver Attributes'>
588<caption>Table 1: <a name='TABLE_1'>Required PostScript Printer Driver Attributes</a></caption>
589<thead>
590<tr>
591	<th>Attribute</th>
592	<th>Description</th>
593</tr>
594</thead>
595<tbody>
596<tr>
597	<td><tt>DefaultColorSpace</tt></td>
598	<td>The default colorspace:
599	<tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or
600	<tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is
601	assumed.</td>
602</tr>
603<tr>
604	<td><tt>LandscapeOrientation</tt></td>
605	<td>The preferred landscape
606	orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or
607	<tt>Any</tt>. If not specified, <tt>Plus90</tt> is
608	assumed.</td>
609</tr>
610<tr>
611	<td><tt>LanguageLevel</tt></td>
612	<td>The PostScript language
613	level supported by the device: 1, 2, or 3. If not
614	specified, 2 is assumed.</td>
615</tr>
616<tr>
617	<td><tt>Product</tt></td>
618	<td>The string returned by
619	the PostScript <tt>product</tt> operator, which
620	<i>must</i> include parenthesis to conform with
621	PostScript syntax rules for strings. Multiple
622	<tt>Product</tt> attributes may be specified to support
623	multiple products with the same PPD file. If not
624	specified, "(ESP Ghostscript)" and "(GNU Ghostscript)"
625	are assumed.</td>
626</tr>
627<tr>
628	<td><tt>PSVersion</tt></td>
629	<td>The PostScript
630	interpreter version numbers as returned by the
631	<tt>version</tt> and <tt>revision</tt> operators. The
632	required format is "(version) revision". Multiple
633	<tt>PSVersion</tt> attributes may be specified to
634	support multiple interpreter version numbers. If not
635	specified, "(3010) 705" and "(3010) 707" are
636	assumed.</td>
637</tr>
638<tr>
639	<td><tt>TTRasterizer</tt></td>
640	<td>The type of TrueType
641	font rasterizer supported by the device, if any. The
642	supported values are <tt>None</tt>, <tt>Accept68k</tt>,
643	<tt>Type42</tt>, and <tt>TrueImage</tt>. If not
644	specified, <tt>None</tt> is assumed.</td>
645</tr>
646</table></div>
647
648<h3>Query Commands</h3>
649
650<p>Most PostScript printer PPD files include query commands (<tt>?PageSize</tt>, etc.) that allow applications to query the printer for its current settings and configuration. Query commands are included in driver information files as attributes. For example, the example in <a href='#LISTING_1'>Listing 1</a> uses the following definition for the <tt>PageSize</tt> query command:</p>
651
652<pre class='example'>
653<a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
654      save
655      currentpagedevice /PageSize get aload pop
656      2 copy gt {exch} if (Unknown)
657      23 dict
658              dup [612 792] (Letter) put
659              dup [612 1008] (Legal) put
660              dup [595 842] (A4) put
661              {exch aload pop 4 index sub abs 5 le exch
662               5 index sub abs 5 le and
663              {exch pop exit} {pop} ifelse
664      } bind forall = flush pop pop
665      restore"
666</pre>
667
668<p>Query commands can span multiple lines, however no single line may contain more than 255 characters.</p>
669
670<h3><a name='IMPORT'>Importing Existing PPD Files</a></h3>
671
672<P>CUPS includes a utility called <a href='man-ppdi.html'>ppdi(1)</a>
673which allows you to import existing PPD files into the driver information file
674format used by the PPD compiler <a href='man-ppdc.html'>ppdc(1)</a>. Once
675imported, you can modify, localize, and regenerate the PPD files easily. Type
676the following command to import the PPD file <VAR>mydevice.ppd</VAR> into the
677driver information file <VAR>mydevice.drv</VAR>:</P>
678
679<pre class='command'>
680ppdi -o mydevice.drv mydevice.ppd
681</pre>
682
683<P>If you have a whole directory of PPD files that you would like to import,
684you can list multiple filenames or use shell wildcards to import more than one
685PPD file on the command-line:</P>
686
687<pre class='command'>
688ppdi -o mydevice.drv mydevice1.ppd mydevice2.ppd
689ppdi -o mydevice.drv *.ppd
690</pre>
691
692<P>If the driver information file already exists, the new PPD
693file entries are appended to the end of the file. Each PPD file
694is placed in its own group of curly braces within the driver
695information file.</P>
696
697
698<h2 class='title'><a name='FILTERS'>Using Custom Filters</a></h2>
699
700<p>Normally a PostScript printer driver will not utilize any additional print filters. For drivers that provide additional filters such as a CUPS command file filter for doing printer maintenance, you must also list the following <tt>Filter</tt> directive to handle printing PostScript files:</p>
701
702<pre class='example'>
703<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 0 -
704</pre>
705
706<h3>Custom Command Filters</h3>
707
708<p>The <tt>application/vnd.cups-command</tt> file type is used for CUPS command files. Use the following <tt>Filter</tt> directive to handle CUPS command files:</p>
709
710<pre class='example'>
711<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-command 100 /path/to/command/filter
712</pre>
713
714<p>To use the standard PostScript command filter, specify <var>commandtops</var> as the path to the command filter.</p>
715
716<h3>Custom PDF Filters</h3>
717
718<p>The <tt>application/pdf</tt> file type is used for unfiltered PDF files while the <tt>application/vnd.cups-pdf</tt> file type is used for filtered PDF files. Use the following <tt>Filter</tt> directive to handle filtered PDF files:</p>
719
720<pre class='example'>
721<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-pdf 100 /path/to/pdf/filter
722</pre>
723
724<p>For unfiltered PDF files, use:</p>
725
726<pre class='example'>
727<a href='ref-ppdcfile.html#Filter'>Filter</a> application/pdf 100 /path/to/pdf/filter
728</pre>
729
730<p>Custom PDF filters that accept filtered data do not need to perform number-up processing and other types of page imposition, while those that accept unfiltered data MUST do the number-up processing themselves.</p>
731
732<h3>Custom PostScript Filters</h3>
733
734<p>The <tt>application/vnd.cups-postscript</tt> file type is used for filtered PostScript files. Use the following <tt>Filter</tt> directive to handle PostScript files:</p>
735
736<pre class='example'>
737<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 100 /path/to/postscript/filter
738</pre>
739
740
741<h2 class='title'><a name='COLOR'>Implementing Color Management</a></h2>
742
743<p>CUPS uses ICC color profiles to provide more accurate color reproduction. The <a href='spec-ppd.html#cupsICCProfile'><tt>cupsICCProfile</tt></a> attribute defines the color profiles that are available for a given printer, for example:</p>
744
745<pre class='example'>
746<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "ColorModel.MediaType.Resolution/Description" /path/to/ICC/profile
747</pre>
748
749<p>where "ColorModel.MediaType.Resolution" defines a selector based on the corresponding option selections. A simple driver might only define profiles for the color models that are supported, for example a printer supporting Gray and RGB might use:</p>
750
751<pre class='example'>
752<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "Gray../Grayscale Profile" /path/to/ICC/gray-profile
753<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "RGB../Full Color Profile" /path/to/ICC/rgb-profile
754</pre>
755
756<p>The options used for profile selection can be customized using the <tt>cupsICCQualifier2</tt> and <tt>cupsICCQualifier3</tt> attributes.</p>
757
758
759<h2 class='title'><a name='MACOSX'>Adding macOS Features</a></h2>
760
761<p>macOS printer drivers can provide <a href='spec-ppd.html#MACOSX'>additional attributes</a> to specify additional option panes in the print dialog, an image of the printer, a help book, and option presets for the driver software:</p>
762
763<pre class='example'>
764<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APDialogExtension "" /Library/Printers/Vendor/filename.plugin
765<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APHelpBook "" /Library/Printers/Vendor/filename.bundle
766<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterIconPath "" /Library/Printers/Vendor/filename.icns
767<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterPreset "name/text" "*option choice ..."
768</pre>
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770  </body>
771</html>
772