doc/help/postscript-driver.html

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 355 <!--
 356   "$Id$"
 357
 358   PostScript printer driver documentation for CUPS.
 359
 360   Copyright 2007-2012 by Apple Inc.
 361   Copyright 1997-2007 by Easy Software Products.
 362
 363   These coded instructions, statements, and computer programs are the
 364   property of Apple Inc. and are protected by Federal copyright
 365   law.  Distribution and use rights are outlined in the file "LICENSE.txt"
 366   which should have been included with this file.  If this file is
 367   file is missing or damaged, see the license at "http://www.cups.org/".
 368 -->
 369
 370 <h1 class='title'>Developing PostScript Printer Drivers</h1>
 371
 372 <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>
 373
 374 <div class='summary'><table summary='General Information'>
 375 <tbody>
 376 <tr>
 377         <th>See Also</th>
 378         <td>Programming: <a href='raster-driver.html'>Developing Raster Printer Drivers</a><br>
 379         Programming: <a href='api-filter.html'>Filter and Backend Programming</a><br>
 380         Programming: <a href='ppd-compiler.html'>Introduction to the PPD Compiler</a><br>
 381         Programming: <a href='api-raster.html'>Raster API</a><br>
 382         References: <a href='ref-ppdcfile.html'>PPD Compiler Driver Information File Reference</a><br>
 383         Specifications: <a href='spec-ppd.html'>CUPS PPD Extensions</a></td>
 384 </tr>
 385 </tbody>
 386 </table></div>
 387 <h2 class="title">Contents</h2>
 388 <ul class="contents">
 389 <li><a href="#BASICS">Printer Driver Basics</a></li>
 390 <li><a href="#CREATING">Creating New PPD Files</a><ul class="subcontents">
 391         <li><a href="#IMPORT">Importing Existing PPD Files</a></li>
 392 </ul></li>
 393 <li><a href="#FILTERS">Using Custom Filters</a></li>
 394 <li><a href="#COLOR">Implementing Color Management</a></li>
 395 <li><a href="#MACOSX">Adding OS X Features</a></li>
 396 </ul>
 397 <h2 class='title'><a name='BASICS'>Printer Driver Basics</a></h2>
 398
 399 <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>
 400
 401 <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>
 402
 403 <div class='figure'><table summary='PostScript Filter Chain'>
 404 <caption>Figure 1: <a name='FIGURE_1'>PostScript Filter Chain</a></caption>
 405 <tr><td><img src='../images/cups-postscript-chain.png' width='700' height='150' alt='PostScript Filter Chain'></td></tr>
 406 </table></div>
 407
 408 <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>
 409
 410 <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>
 411
 412 <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>
 413
 414 <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>
 415
 416 <div class='figure'><table summary='Command Filter Chain'>
 417 <caption>Figure 2: <a name='FIGURE_2'>Command Filter Chain</a></caption>
 418 <tr><td><img src='../images/cups-command-chain.png' width='575' height='150' alt='Command Filter Chain'></td></tr>
 419 </table></div>
 420
 421 <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>
 422
 423
 424 <h2 class='title'><a name='CREATING'>Creating New PPD Files</a></h2>
 425
 426 <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>
 427
 428 <p class='example'>Listing 1: <a name='LISTING_1'>"examples/postscript.drv"</a></p>
 429
 430 <pre class='example'>
 431 // Include standard font and media definitions
 432 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;font.defs&gt;
 433 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;media.defs&gt;
 434
 435 // Specify this is a PostScript printer driver
 436 <a href='ref-ppdcfile.html#DriverType'>DriverType</a> ps
 437
 438 // List the fonts that are supported, in this case all standard fonts
 439 <a href='ref-ppdcfile.html#Font'>Font</a> *
 440
 441 // Manufacturer, model name, and version
 442 <a href='ref-ppdcfile.html#Manufacturer'>Manufacturer</a> "Foo"
 443 <a href='ref-ppdcfile.html#ModelName'>ModelName</a> "Foo LaserProofer 2000"
 444 <a href='ref-ppdcfile.html#Version'>Version</a> 1.0
 445
 446 // PostScript printer attributes
 447 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 448 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 449 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 450 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 451 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 452 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 453
 454 // Supported page sizes
 455 *<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Letter
 456 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Legal
 457 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> A4
 458
 459 // Query command for page size
 460 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 461       save
 462       currentpagedevice /PageSize get aload pop
 463       2 copy gt {exch} if (Unknown)
 464       23 dict
 465               dup [612 792] (Letter) put
 466               dup [612 1008] (Legal) put
 467               dup [595 842] (A4) put
 468               {exch aload pop 4 index sub abs 5 le exch
 469                5 index sub abs 5 le and
 470               {exch pop exit} {pop} ifelse
 471       } bind forall = flush pop pop
 472       restore"
 473
 474 // Specify the name of the PPD file we want to generate
 475 <a href='ref-ppdcfile.html#PCFileName'>PCFileName</a> "fooproof.ppd"
 476 </pre>
 477
 478 <h3>Required Attributes</h3>
 479
 480 <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>
 481
 482 <pre class='example'>
 483 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 484 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 485 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 486 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 487 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 488 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 489 </pre>
 490
 491 <div class='table'><table summary='Required PostScript Printer Driver Attributes'>
 492 <caption>Table 1: <a name='TABLE_1'>Required PostScript Printer Driver Attributes</a></caption>
 493 <thead>
 494 <tr>
 495         <th>Attribute</th>
 496         <th>Description</th>
 497 </tr>
 498 </thead>
 499 <tbody>
 500 <tr>
 501         <td><tt>DefaultColorSpace</tt></td>
 502         <td>The default colorspace:
 503         <tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or
 504         <tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is
 505         assumed.</td>
 506 </tr>
 507 <tr>
 508         <td><tt>LandscapeOrientation</tt></td>
 509         <td>The preferred landscape
 510         orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or
 511         <tt>Any</tt>. If not specified, <tt>Plus90</tt> is
 512         assumed.</td>
 513 </tr>
 514 <tr>
 515         <td><tt>LanguageLevel</tt></td>
 516         <td>The PostScript language
 517         level supported by the device: 1, 2, or 3. If not
 518         specified, 2 is assumed.</td>
 519 </tr>
 520 <tr>
 521         <td><tt>Product</tt></td>
 522         <td>The string returned by
 523         the PostScript <tt>product</tt> operator, which
 524         <i>must</i> include parenthesis to conform with
 525         PostScript syntax rules for strings. Multiple
 526         <tt>Product</tt> attributes may be specified to support
 527         multiple products with the same PPD file. If not
 528         specified, "(ESP Ghostscript)" and "(GNU Ghostscript)"
 529         are assumed.</td>
 530 </tr>
 531 <tr>
 532         <td><tt>PSVersion</tt></td>
 533         <td>The PostScript
 534         interpreter version numbers as returned by the
 535         <tt>version</tt> and <tt>revision</tt> operators. The
 536         required format is "(version) revision". Multiple
 537         <tt>PSVersion</tt> attributes may be specified to
 538         support multiple interpreter version numbers. If not
 539         specified, "(3010) 705" and "(3010) 707" are
 540         assumed.</td>
 541 </tr>
 542 <tr>
 543         <td><tt>TTRasterizer</tt></td>
 544         <td>The type of TrueType
 545         font rasterizer supported by the device, if any. The
 546         supported values are <tt>None</tt>, <tt>Accept68k</tt>,
 547         <tt>Type42</tt>, and <tt>TrueImage</tt>. If not
 548         specified, <tt>None</tt> is assumed.</td>
 549 </tr>
 550 </table></div>
 551
 552 <h3>Query Commands</h3>
 553
 554 <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>
 555
 556 <pre class='example'>
 557 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 558       save
 559       currentpagedevice /PageSize get aload pop
 560       2 copy gt {exch} if (Unknown)
 561       23 dict
 562               dup [612 792] (Letter) put
 563               dup [612 1008] (Legal) put
 564               dup [595 842] (A4) put
 565               {exch aload pop 4 index sub abs 5 le exch
 566                5 index sub abs 5 le and
 567               {exch pop exit} {pop} ifelse
 568       } bind forall = flush pop pop
 569       restore"
 570 </pre>
 571
 572 <p>Query commands can span multiple lines, however no single line may contain more than 255 characters.</p>
 573
 574 <h3><a name='IMPORT'>Importing Existing PPD Files</a></h3>
 575
 576 <P>CUPS includes a utility called <a href='man-ppdi.html'>ppdi(1)</a>
 577 which allows you to import existing PPD files into the driver information file
 578 format used by the PPD compiler <a href='man-ppdc.html'>ppdc(1)</a>. Once
 579 imported, you can modify, localize, and regenerate the PPD files easily. Type
 580 the following command to import the PPD file <VAR>mydevice.ppd</VAR> into the
 581 driver information file <VAR>mydevice.drv</VAR>:</P>
 582
 583 <pre class='command'>
 584 ppdi -o mydevice.drv mydevice.ppd
 585 </pre>
 586
 587 <P>If you have a whole directory of PPD files that you would like to import,
 588 you can list multiple filenames or use shell wildcards to import more than one
 589 PPD file on the command-line:</P>
 590
 591 <pre class='command'>
 592 ppdi -o mydevice.drv mydevice1.ppd mydevice2.ppd
 593 ppdi -o mydevice.drv *.ppd
 594 </pre>
 595
 596 <P>If the driver information file already exists, the new PPD
 597 file entries are appended to the end of the file. Each PPD file
 598 is placed in its own group of curly braces within the driver
 599 information file.</P>
 600
 601
 602 <h2 class='title'><a name='FILTERS'>Using Custom Filters</a></h2>
 603
 604 <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>
 605
 606 <pre class='example'>
 607 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 0 -
 608 </pre>
 609
 610 <h3>Custom Command Filters</h3>
 611
 612 <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>
 613
 614 <pre class='example'>
 615 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-command 100 /path/to/command/filter
 616 </pre>
 617
 618 <p>To use the standard PostScript command filter, specify <var>commandtops</var> as the path to the command filter.</p>
 619
 620 <h3>Custom PDF Filters</h3>
 621
 622 <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>
 623
 624 <pre class='example'>
 625 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-pdf 100 /path/to/pdf/filter
 626 </pre>
 627
 628 <p>For unfiltered PDF files, use:</p>
 629
 630 <pre class='example'>
 631 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/pdf 100 /path/to/pdf/filter
 632 </pre>
 633
 634 <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>
 635
 636 <h3>Custom PostScript Filters</h3>
 637
 638 <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>
 639
 640 <pre class='example'>
 641 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 100 /path/to/postscript/filter
 642 </pre>
 643
 644
 645 <h2 class='title'><a name='COLOR'>Implementing Color Management</a></h2>
 646
 647 <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>
 648
 649 <pre class='example'>
 650 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "ColorModel.MediaType.Resolution/Description" /path/to/ICC/profile
 651 </pre>
 652
 653 <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>
 654
 655 <pre class='example'>
 656 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "Gray../Grayscale Profile" /path/to/ICC/gray-profile
 657 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "RGB../Full Color Profile" /path/to/ICC/rgb-profile
 658 </pre>
 659
 660 <p>The options used for profile selection can be customized using the <tt>cupsICCQualifier2</tt> and <tt>cupsICCQualifier3</tt> attributes.</p>
 661
 662
 663 <h2 class='title'><a name='MACOSX'>Adding OS X Features</a></h2>
 664
 665 <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>
 666
 667 <pre class='example'>
 668 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APDialogExtension "" /Library/Printers/Vendor/filename.plugin
 669 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APHelpBook "" /Library/Printers/Vendor/filename.bundle
 670 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterIconPath "" /Library/Printers/Vendor/filename.icns
 671 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterPreset "name/text" "*option choice ..."
 672 </pre>
 673 </div>
 674 </body>
 675 </html>