doc/help/postscript-driver.html

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 337 </head>
 338 <body>
 339 <div class='body'>
 340 <h1 class='title'>Developing PostScript Printer Drivers</h1>
 341
 342 <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 Mac OS X features</a>.</p>
 343
 344 <div class='summary'><table summary='General Information'>
 345 <tbody>
 346 <tr>
 347         <th>See Also</th>
 348         <td>Programming: <a href='raster-driver.html'>Developing Raster Printer Drivers</a><br>
 349         Programming: <a href='api-filter.html'>Filter and Backend Programming</a><br>
 350         Programming: <a href='ppd-compiler.html'>Introduction to the PPD Compiler</a><br>
 351         Programming: <a href='api-raster.html'>Raster API</a><br>
 352         References: <a href='ref-ppdcfile.html'>PPD Compiler Driver Information File Reference</a><br>
 353         Specifications: <a href='spec-ppd.html'>CUPS PPD Extensions</a></td>
 354 </tr>
 355 </tbody>
 356 </table></div>
 357 <h2 class="title">Contents</h2>
 358 <ul class="contents">
 359 <ul class="subcontents">
 360 <li><a href="#BASICS">Printer Driver Basics</a></li>
 361 <li><a href="#CREATING">Creating New PPD Files</a><ul class="subcontents">
 362 <li><a href="#IMPORT">Importing Existing PPD Files</a></li>
 363 </ul></li>
 364 <li><a href="#FILTERS">Using Custom Filters</a></li>
 365 <li><a href="#COLOR">Implementing Color Management</a></li>
 366 <li><a href="#MACOSX">Adding Mac OS X Features</a></li>
 367 <h2 class='title'><a name='BASICS'>Printer Driver Basics</a></h2>
 368
 369 <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>
 370
 371 <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>
 372
 373 <div class='figure'><table summary='PostScript Filter Chain'>
 374 <caption>Figure 1: <a name='FIGURE_1'>PostScript Filter Chain</a></caption>
 375 <tr><td><img src='/images/cups-postscript-chain.png' width='700' height='150' alt='PostScript Filter Chain'></td></tr>
 376 </table></div>
 377
 378 <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>
 379
 380 <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>
 381
 382 <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>
 383
 384 <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>
 385
 386 <div class='figure'><table summary='Command Filter Chain'>
 387 <caption>Figure 2: <a name='FIGURE_2'>Command Filter Chain</a></caption>
 388 <tr><td><img src='/images/cups-command-chain.png' width='575' height='150' alt='Command Filter Chain'></td></tr>
 389 </table></div>
 390
 391 <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>
 392
 393
 394 <h2 class='title'><a name='CREATING'>Creating New PPD Files</a></h2>
 395
 396 <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>
 397
 398 <p class='example'>Listing 1: <a name='LISTING_1'>"examples/postscript.drv"</a></p>
 399
 400 <pre class='example'>
 401 // Include standard font and media definitions
 402 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;font.defs&gt;
 403 <a href='ref-ppdcfile.html#_include'>#include</a> &lt;media.defs&gt;
 404
 405 // Specify this is a PostScript printer driver
 406 <a href='ref-ppdcfile.html#DriverType'>DriverType</a> ps
 407
 408 // List the fonts that are supported, in this case all standard fonts
 409 <a href='ref-ppdcfile.html#Font'>Font</a> *
 410
 411 // Manufacturer, model name, and version
 412 <a href='ref-ppdcfile.html#Manufacturer'>Manufacturer</a> "Foo"
 413 <a href='ref-ppdcfile.html#ModelName'>ModelName</a> "Foo LaserProofer 2000"
 414 <a href='ref-ppdcfile.html#Version'>Version</a> 1.0
 415
 416 // PostScript printer attributes
 417 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 418 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 419 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 420 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 421 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 422 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 423
 424 // Supported page sizes
 425 *<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Letter
 426 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Legal
 427 <a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> A4
 428
 429 // Query command for page size
 430 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 431       save
 432       currentpagedevice /PageSize get aload pop
 433       2 copy gt {exch} if (Unknown)
 434       23 dict
 435               dup [612 792] (Letter) put
 436               dup [612 1008] (Legal) put
 437               dup [595 842] (A4) put
 438               {exch aload pop 4 index sub abs 5 le exch
 439                5 index sub abs 5 le and
 440               {exch pop exit} {pop} ifelse
 441       } bind forall = flush pop pop
 442       restore"
 443
 444 // Specify the name of the PPD file we want to generate
 445 <a href='ref-ppdcfile.html#PCFileName'>PCFileName</a> "fooproof.ppd"
 446 </pre>
 447
 448 <h3>Required Attributes</h3>
 449
 450 <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>
 451
 452 <pre class='example'>
 453 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray
 454 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90
 455 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3"
 456 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)"
 457 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0"
 458 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42
 459 </pre>
 460
 461 <div class='table'><table summary='Required PostScript Printer Driver Attributes'>
 462 <caption>Table 1: <a name='TABLE_1'>Required PostScript Printer Driver Attributes</a></caption>
 463 <thead>
 464 <tr>
 465         <th>Attribute</th>
 466         <th>Description</th>
 467 </tr>
 468 </thead>
 469 <tbody>
 470 <tr>
 471         <td><tt>DefaultColorSpace</tt></td>
 472         <td>The default colorspace:
 473         <tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or
 474         <tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is
 475         assumed.</td>
 476 </tr>
 477 <tr>
 478         <td><tt>LandscapeOrientation</tt></td>
 479         <td>The preferred landscape
 480         orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or
 481         <tt>Any</tt>. If not specified, <tt>Plus90</tt> is
 482         assumed.</td>
 483 </tr>
 484 <tr>
 485         <td><tt>LanguageLevel</tt></td>
 486         <td>The PostScript language
 487         level supported by the device: 1, 2, or 3. If not
 488         specified, 2 is assumed.</td>
 489 </tr>
 490 <tr>
 491         <td><tt>Product</tt></td>
 492         <td>The string returned by
 493         the PostScript <tt>product</tt> operator, which
 494         <i>must</i> include parenthesis to conform with
 495         PostScript syntax rules for strings. Multiple
 496         <tt>Product</tt> attributes may be specified to support
 497         multiple products with the same PPD file. If not
 498         specified, "(ESP Ghostscript)" and "(GNU Ghostscript)"
 499         are assumed.</td>
 500 </tr>
 501 <tr>
 502         <td><tt>PSVersion</tt></td>
 503         <td>The PostScript
 504         interpreter version numbers as returned by the
 505         <tt>version</tt> and <tt>revision</tt> operators. The
 506         required format is "(version) revision". Multiple
 507         <tt>PSVersion</tt> attributes may be specified to
 508         support multiple interpreter version numbers. If not
 509         specified, "(3010) 705" and "(3010) 707" are
 510         assumed.</td>
 511 </tr>
 512 <tr>
 513         <td><tt>TTRasterizer</tt></td>
 514         <td>The type of TrueType
 515         font rasterizer supported by the device, if any. The
 516         supported values are <tt>None</tt>, <tt>Accept68k</tt>,
 517         <tt>Type42</tt>, and <tt>TrueImage</tt>. If not
 518         specified, <tt>None</tt> is assumed.</td>
 519 </tr>
 520 </table></div>
 521
 522 <h3>Query Commands</h3>
 523
 524 <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>
 525
 526 <pre class='example'>
 527 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" "
 528       save
 529       currentpagedevice /PageSize get aload pop
 530       2 copy gt {exch} if (Unknown)
 531       23 dict
 532               dup [612 792] (Letter) put
 533               dup [612 1008] (Legal) put
 534               dup [595 842] (A4) put
 535               {exch aload pop 4 index sub abs 5 le exch
 536                5 index sub abs 5 le and
 537               {exch pop exit} {pop} ifelse
 538       } bind forall = flush pop pop
 539       restore"
 540 </pre>
 541
 542 <p>Query commands can span multiple lines, however no single line may contain more than 255 characters.</p>
 543
 544 <h3><a name='IMPORT'>Importing Existing PPD Files</a></h3>
 545
 546 <P>CUPS includes a utility called <a href='man-ppdi.html'>ppdi(1)</a>
 547 which allows you to import existing PPD files into the driver information file
 548 format used by the PPD compiler <a href='man-ppdc.html'>ppdc(1)</a>. Once
 549 imported, you can modify, localize, and regenerate the PPD files easily. Type
 550 the following command to import the PPD file <VAR>mydevice.ppd</VAR> into the
 551 driver information file <VAR>mydevice.drv</VAR>:</P>
 552
 553 <pre class='command'>
 554 ppdi -o mydevice.drv mydevice.ppd
 555 </pre>
 556
 557 <P>If you have a whole directory of PPD files that you would like to import,
 558 you can list multiple filenames or use shell wildcards to import more than one
 559 PPD file on the command-line:</P>
 560
 561 <pre class='command'>
 562 ppdi -o mydevice.drv mydevice1.ppd mydevice2.ppd
 563 ppdi -o mydevice.drv *.ppd
 564 </pre>
 565
 566 <P>If the driver information file already exists, the new PPD
 567 file entries are appended to the end of the file. Each PPD file
 568 is placed in its own group of curly braces within the driver
 569 information file.</P>
 570
 571
 572 <h2 class='title'><a name='FILTERS'>Using Custom Filters</a></h2>
 573
 574 <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>
 575
 576 <pre class='example'>
 577 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 0 -
 578 </pre>
 579
 580 <h3>Custom Command Filters</h3>
 581
 582 <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>
 583
 584 <pre class='example'>
 585 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-command 100 /path/to/command/filter
 586 </pre>
 587
 588 <p>To use the standard PostScript command filter, specify <var>commandtops</var> as the path to the command filter.</p>
 589
 590 <h3>Custom PDF Filters</h3>
 591
 592 <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>
 593
 594 <pre class='example'>
 595 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-pdf 100 /path/to/pdf/filter
 596 </pre>
 597
 598 <p>For unfiltered PDF files, use:</p>
 599
 600 <pre class='example'>
 601 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/pdf 100 /path/to/pdf/filter
 602 </pre>
 603
 604 <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>
 605
 606 <h3>Custom PostScript Filters</h3>
 607
 608 <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>
 609
 610 <pre class='example'>
 611 <a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 100 /path/to/postscript/filter
 612 </pre>
 613
 614
 615 <h2 class='title'><a name='COLOR'>Implementing Color Management</a></h2>
 616
 617 <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>
 618
 619 <pre class='example'>
 620 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "ColorModel.MediaType.Resolution/Description" /path/to/ICC/profile
 621 </pre>
 622
 623 <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>
 624
 625 <pre class='example'>
 626 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "Gray../Grayscale Profile" /path/to/ICC/gray-profile
 627 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "RGB../Full Color Profile" /path/to/ICC/rgb-profile
 628 </pre>
 629
 630 <p>The options used for profile selection can be customized using the <tt>cupsICCQualifier2</tt> and <tt>cupsICCQualifier3</tt> attributes.</p>
 631
 632
 633 <h2 class='title'><a name='MACOSX'>Adding Mac OS X Features</a></h2>
 634
 635 <p>Mac 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>
 636
 637 <pre class='example'>
 638 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APDialogExtension "" /Library/Printers/Vendor/filename.plugin
 639 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APHelpBook "" /Library/Printers/Vendor/filename.bundle
 640 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterIconPath "" /Library/Printers/Vendor/filename.icns
 641 <a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterPreset "name/text" "*option choice ..."
 642 </pre>
 643 </div>
 644 </body>
 645 </html>