doc/help/postscript-driver.html

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 343 <!--
 344   "$Id$"
 345
 346   PostScript printer driver documentation for CUPS.
 347
 348   Copyright 2007-2012 by Apple Inc.
 349   Copyright 1997-2007 by Easy Software Products.
 350
 351   These coded instructions, statements, and computer programs are the
 352   property of Apple Inc. and are protected by Federal copyright
 353   law.  Distribution and use rights are outlined in the file "LICENSE.txt"
 354   which should have been included with this file.  If this file is
 355   file is missing or damaged, see the license at "http://www.cups.org/".
 356 -->
 357
 358 <h1 class='title'>Developing PostScript Printer Drivers</h1>
 359
 360 <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 OS X features</a>.</p>
 361
 362 <div class='summary'><table summary='General Information'>
 363 <tbody>
 364 <tr>
 365         <th>See Also</th>
 366         <td>Programming: <a href='raster-driver.html'>Developing Raster Printer Drivers</a><br>
 367         Programming: <a href='api-filter.html'>Filter and Backend Programming</a><br>
 368         Programming: <a href='ppd-compiler.html'>Introduction to the PPD Compiler</a><br>
 369         Programming: <a href='api-raster.html'>Raster API</a><br>
 370         References: <a href='ref-ppdcfile.html'>PPD Compiler Driver Information File Reference</a><br>
 371         Specifications: <a href='spec-ppd.html'>CUPS PPD Extensions</a></td>
 372 </tr>
 373 </tbody>
 374 </table></div>
 375 <h2 class="title">Contents</h2>
 376 <ul class="contents">
 377 <li><a href="#BASICS">Printer Driver Basics</a></li>
 378 <li><a href="#CREATING">Creating New PPD Files</a><ul class="subcontents">
 379         <li><a href="#IMPORT">Importing Existing PPD Files</a></li>
 380 </ul></li>
 381 <li><a href="#FILTERS">Using Custom Filters</a></li>
 382 <li><a href="#COLOR">Implementing Color Management</a></li>
 383 <li><a href="#MACOSX">Adding OS X Features</a></li>
 384 </ul>
 385 <h2 class='title'><a name='BASICS'>Printer Driver Basics</a></h2>
 386
 387 <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>
 388
 389 <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>
 390
 391 <div class='figure'><table summary='PostScript Filter Chain'>
 392 <caption>Figure 1: <a name='FIGURE_1'>PostScript Filter Chain</a></caption>
 393 <tr><td><img src='../images/cups-postscript-chain.png' width='700' height='150' alt='PostScript Filter Chain'></td></tr>
 394 </table></div>
 395
 396 <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>
 397
 398 <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>
 399
 400 <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>
 401
 402 <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>
 403
 404 <div class='figure'><table summary='Command Filter Chain'>
 405 <caption>Figure 2: <a name='FIGURE_2'>Command Filter Chain</a></caption>
 406 <tr><td><img src='../images/cups-command-chain.png' width='575' height='150' alt='Command Filter Chain'></td></tr>
 407 </table></div>
 408
 409 <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>
 410
 411
 412 <h2 class='title'><a name='CREATING'>Creating New PPD Files</a></h2>
 413
 414 <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>
 415
 416 <p class='example'>Listing 1: <a name='LISTING_1'>"examples/postscript.drv"</a></p>
 417
 418 <pre class='example'>
 419 // Include standard font and media definitions
 420 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;font.defs&gt;
 421 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;media.defs&gt;
 422
 423 // Specify this is a PostScript printer driver
 424 <a href='ref-ppdcfile.html#DriverType'>DriverType</a> ps
 425
 426 // List the fonts that are supported, in this case all standard fonts
 427 <a href='ref-ppdcfile.html#Font'>Font</a> *
 428
 429 // Manufacturer, model name, and version
 430 <a href='ref-ppdcfile.html#Manufacturer'>Manufacturer</a> "Foo"
 431 <a href='ref-ppdcfile.html#ModelName'>ModelName</a> "Foo LaserProofer 2000"
 432 <a href='ref-ppdcfile.html#Version'>Version</a> 1.0
 433
 434 // PostScript printer attributes
 435 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 436 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 437 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 438 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 439 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 440 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 441
 442 // Supported page sizes
 443 *<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Letter
 444 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Legal
 445 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> A4
 446
 447 // Query command for page size
 448 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 449       save
 450       currentpagedevice /PageSize get aload pop
 451       2 copy gt {exch} if (Unknown)
 452       23 dict
 453               dup [612 792] (Letter) put
 454               dup [612 1008] (Legal) put
 455               dup [595 842] (A4) put
 456               {exch aload pop 4 index sub abs 5 le exch
 457                5 index sub abs 5 le and
 458               {exch pop exit} {pop} ifelse
 459       } bind forall = flush pop pop
 460       restore"
 461
 462 // Specify the name of the PPD file we want to generate
 463 <a href='ref-ppdcfile.html#PCFileName'>PCFileName</a> "fooproof.ppd"
 464 </pre>
 465
 466 <h3>Required Attributes</h3>
 467
 468 <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>
 469
 470 <pre class='example'>
 471 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 472 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 473 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 474 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 475 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 476 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 477 </pre>
 478
 479 <div class='table'><table summary='Required PostScript Printer Driver Attributes'>
 480 <caption>Table 1: <a name='TABLE_1'>Required PostScript Printer Driver Attributes</a></caption>
 481 <thead>
 482 <tr>
 483         <th>Attribute</th>
 484         <th>Description</th>
 485 </tr>
 486 </thead>
 487 <tbody>
 488 <tr>
 489         <td><tt>DefaultColorSpace</tt></td>
 490         <td>The default colorspace:
 491         <tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or
 492         <tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is
 493         assumed.</td>
 494 </tr>
 495 <tr>
 496         <td><tt>LandscapeOrientation</tt></td>
 497         <td>The preferred landscape
 498         orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or
 499         <tt>Any</tt>. If not specified, <tt>Plus90</tt> is
 500         assumed.</td>
 501 </tr>
 502 <tr>
 503         <td><tt>LanguageLevel</tt></td>
 504         <td>The PostScript language
 505         level supported by the device: 1, 2, or 3. If not
 506         specified, 2 is assumed.</td>
 507 </tr>
 508 <tr>
 509         <td><tt>Product</tt></td>
 510         <td>The string returned by
 511         the PostScript <tt>product</tt> operator, which
 512         <i>must</i> include parenthesis to conform with
 513         PostScript syntax rules for strings. Multiple
 514         <tt>Product</tt> attributes may be specified to support
 515         multiple products with the same PPD file. If not
 516         specified, "(ESP Ghostscript)" and "(GNU Ghostscript)"
 517         are assumed.</td>
 518 </tr>
 519 <tr>
 520         <td><tt>PSVersion</tt></td>
 521         <td>The PostScript
 522         interpreter version numbers as returned by the
 523         <tt>version</tt> and <tt>revision</tt> operators. The
 524         required format is "(version) revision". Multiple
 525         <tt>PSVersion</tt> attributes may be specified to
 526         support multiple interpreter version numbers. If not
 527         specified, "(3010) 705" and "(3010) 707" are
 528         assumed.</td>
 529 </tr>
 530 <tr>
 531         <td><tt>TTRasterizer</tt></td>
 532         <td>The type of TrueType
 533         font rasterizer supported by the device, if any. The
 534         supported values are <tt>None</tt>, <tt>Accept68k</tt>,
 535         <tt>Type42</tt>, and <tt>TrueImage</tt>. If not
 536         specified, <tt>None</tt> is assumed.</td>
 537 </tr>
 538 </table></div>
 539
 540 <h3>Query Commands</h3>
 541
 542 <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>
 543
 544 <pre class='example'>
 545 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 546       save
 547       currentpagedevice /PageSize get aload pop
 548       2 copy gt {exch} if (Unknown)
 549       23 dict
 550               dup [612 792] (Letter) put
 551               dup [612 1008] (Legal) put
 552               dup [595 842] (A4) put
 553               {exch aload pop 4 index sub abs 5 le exch
 554                5 index sub abs 5 le and
 555               {exch pop exit} {pop} ifelse
 556       } bind forall = flush pop pop
 557       restore"
 558 </pre>
 559
 560 <p>Query commands can span multiple lines, however no single line may contain more than 255 characters.</p>
 561
 562 <h3><a name='IMPORT'>Importing Existing PPD Files</a></h3>
 563
 564 <P>CUPS includes a utility called <a href='man-ppdi.html'>ppdi(1)</a>
 565 which allows you to import existing PPD files into the driver information file
 566 format used by the PPD compiler <a href='man-ppdc.html'>ppdc(1)</a>. Once
 567 imported, you can modify, localize, and regenerate the PPD files easily. Type
 568 the following command to import the PPD file <VAR>mydevice.ppd</VAR> into the
 569 driver information file <VAR>mydevice.drv</VAR>:</P>
 570
 571 <pre class='command'>
 572 ppdi -o mydevice.drv mydevice.ppd
 573 </pre>
 574
 575 <P>If you have a whole directory of PPD files that you would like to import,
 576 you can list multiple filenames or use shell wildcards to import more than one
 577 PPD file on the command-line:</P>
 578
 579 <pre class='command'>
 580 ppdi -o mydevice.drv mydevice1.ppd mydevice2.ppd
 581 ppdi -o mydevice.drv *.ppd
 582 </pre>
 583
 584 <P>If the driver information file already exists, the new PPD
 585 file entries are appended to the end of the file. Each PPD file
 586 is placed in its own group of curly braces within the driver
 587 information file.</P>
 588
 589
 590 <h2 class='title'><a name='FILTERS'>Using Custom Filters</a></h2>
 591
 592 <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>
 593
 594 <pre class='example'>
 595 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 0 -
 596 </pre>
 597
 598 <h3>Custom Command Filters</h3>
 599
 600 <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>
 601
 602 <pre class='example'>
 603 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-command 100 /path/to/command/filter
 604 </pre>
 605
 606 <p>To use the standard PostScript command filter, specify <var>commandtops</var> as the path to the command filter.</p>
 607
 608 <h3>Custom PDF Filters</h3>
 609
 610 <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>
 611
 612 <pre class='example'>
 613 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-pdf 100 /path/to/pdf/filter
 614 </pre>
 615
 616 <p>For unfiltered PDF files, use:</p>
 617
 618 <pre class='example'>
 619 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/pdf 100 /path/to/pdf/filter
 620 </pre>
 621
 622 <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>
 623
 624 <h3>Custom PostScript Filters</h3>
 625
 626 <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>
 627
 628 <pre class='example'>
 629 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 100 /path/to/postscript/filter
 630 </pre>
 631
 632
 633 <h2 class='title'><a name='COLOR'>Implementing Color Management</a></h2>
 634
 635 <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>
 636
 637 <pre class='example'>
 638 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "ColorModel.MediaType.Resolution/Description" /path/to/ICC/profile
 639 </pre>
 640
 641 <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>
 642
 643 <pre class='example'>
 644 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "Gray../Grayscale Profile" /path/to/ICC/gray-profile
 645 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "RGB../Full Color Profile" /path/to/ICC/rgb-profile
 646 </pre>
 647
 648 <p>The options used for profile selection can be customized using the <tt>cupsICCQualifier2</tt> and <tt>cupsICCQualifier3</tt> attributes.</p>
 649
 650
 651 <h2 class='title'><a name='MACOSX'>Adding OS X Features</a></h2>
 652
 653 <p>OS X 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>
 654
 655 <pre class='example'>
 656 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APDialogExtension "" /Library/Printers/Vendor/filename.plugin
 657 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APHelpBook "" /Library/Printers/Vendor/filename.bundle
 658 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterIconPath "" /Library/Printers/Vendor/filename.icns
 659 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterPreset "name/text" "*option choice ..."
 660 </pre>
 661 </div>
 662 </body>
 663 </html>