1<h2 class='title'><a name='BASICS'>Printer Driver Basics</a></h2> 2 3<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> 4 5<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> 6 7<div class='figure'><table summary='PostScript Filter Chain'> 8<caption>Figure 1: <a name='FIGURE_1'>PostScript Filter Chain</a></caption> 9<tr><td><img src='../images/cups-postscript-chain.png' width='700' height='150' alt='PostScript Filter Chain'></td></tr> 10</table></div> 11 12<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> 13 14<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> 15 16<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> 17 18<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> 19 20<div class='figure'><table summary='Command Filter Chain'> 21<caption>Figure 2: <a name='FIGURE_2'>Command Filter Chain</a></caption> 22<tr><td><img src='../images/cups-command-chain.png' width='575' height='150' alt='Command Filter Chain'></td></tr> 23</table></div> 24 25<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> 26 27 28<h2 class='title'><a name='CREATING'>Creating New PPD Files</a></h2> 29 30<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> 31 32<p class='example'>Listing 1: <a name='LISTING_1'>"examples/postscript.drv"</a></p> 33 34<pre class='example'> 35// Include standard font and media definitions 36<a href='ref-ppdcfile.html#_include'>#include</a> <font.defs> 37<a href='ref-ppdcfile.html#_include'>#include</a> <media.defs> 38 39// Specify this is a PostScript printer driver 40<a href='ref-ppdcfile.html#DriverType'>DriverType</a> ps 41 42// List the fonts that are supported, in this case all standard fonts 43<a href='ref-ppdcfile.html#Font'>Font</a> * 44 45// Manufacturer, model name, and version 46<a href='ref-ppdcfile.html#Manufacturer'>Manufacturer</a> "Foo" 47<a href='ref-ppdcfile.html#ModelName'>ModelName</a> "Foo LaserProofer 2000" 48<a href='ref-ppdcfile.html#Version'>Version</a> 1.0 49 50// PostScript printer attributes 51<a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray 52<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90 53<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3" 54<a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)" 55<a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0" 56<a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42 57 58// Supported page sizes 59*<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Letter 60<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> Legal 61<a href='ref-ppdcfile.html#MediaSize'>MediaSize</a> A4 62 63// Query command for page size 64<a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" " 65 save 66 currentpagedevice /PageSize get aload pop 67 2 copy gt {exch} if (Unknown) 68 23 dict 69 dup [612 792] (Letter) put 70 dup [612 1008] (Legal) put 71 dup [595 842] (A4) put 72 {exch aload pop 4 index sub abs 5 le exch 73 5 index sub abs 5 le and 74 {exch pop exit} {pop} ifelse 75 } bind forall = flush pop pop 76 restore" 77 78// Specify the name of the PPD file we want to generate 79<a href='ref-ppdcfile.html#PCFileName'>PCFileName</a> "fooproof.ppd" 80</pre> 81 82<h3>Required Attributes</h3> 83 84<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> 85 86<pre class='example'> 87<a href='ref-ppdcfile.html#Attribute'>Attribute</a> DefaultColorSpace "" Gray 88<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LandscapeOrientation "" Minus90 89<a href='ref-ppdcfile.html#Attribute'>Attribute</a> LanguageLevel "" "3" 90<a href='ref-ppdcfile.html#Attribute'>Attribute</a> Product "" "(Foo LaserProofer 2000)" 91<a href='ref-ppdcfile.html#Attribute'>Attribute</a> PSVersion "" "(3010) 0" 92<a href='ref-ppdcfile.html#Attribute'>Attribute</a> TTRasterizer "" Type42 93</pre> 94 95<div class='table'><table summary='Required PostScript Printer Driver Attributes'> 96<caption>Table 1: <a name='TABLE_1'>Required PostScript Printer Driver Attributes</a></caption> 97<thead> 98<tr> 99 <th>Attribute</th> 100 <th>Description</th> 101</tr> 102</thead> 103<tbody> 104<tr> 105 <td><tt>DefaultColorSpace</tt></td> 106 <td>The default colorspace: 107 <tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or 108 <tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is 109 assumed.</td> 110</tr> 111<tr> 112 <td><tt>LandscapeOrientation</tt></td> 113 <td>The preferred landscape 114 orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or 115 <tt>Any</tt>. If not specified, <tt>Plus90</tt> is 116 assumed.</td> 117</tr> 118<tr> 119 <td><tt>LanguageLevel</tt></td> 120 <td>The PostScript language 121 level supported by the device: 1, 2, or 3. If not 122 specified, 2 is assumed.</td> 123</tr> 124<tr> 125 <td><tt>Product</tt></td> 126 <td>The string returned by 127 the PostScript <tt>product</tt> operator, which 128 <i>must</i> include parenthesis to conform with 129 PostScript syntax rules for strings. Multiple 130 <tt>Product</tt> attributes may be specified to support 131 multiple products with the same PPD file. If not 132 specified, "(ESP Ghostscript)" and "(GNU Ghostscript)" 133 are assumed.</td> 134</tr> 135<tr> 136 <td><tt>PSVersion</tt></td> 137 <td>The PostScript 138 interpreter version numbers as returned by the 139 <tt>version</tt> and <tt>revision</tt> operators. The 140 required format is "(version) revision". Multiple 141 <tt>PSVersion</tt> attributes may be specified to 142 support multiple interpreter version numbers. If not 143 specified, "(3010) 705" and "(3010) 707" are 144 assumed.</td> 145</tr> 146<tr> 147 <td><tt>TTRasterizer</tt></td> 148 <td>The type of TrueType 149 font rasterizer supported by the device, if any. The 150 supported values are <tt>None</tt>, <tt>Accept68k</tt>, 151 <tt>Type42</tt>, and <tt>TrueImage</tt>. If not 152 specified, <tt>None</tt> is assumed.</td> 153</tr> 154</table></div> 155 156<h3>Query Commands</h3> 157 158<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> 159 160<pre class='example'> 161<a href='ref-ppdcfile.html#Attribute'>Attribute</a> "?PageSize" "" " 162 save 163 currentpagedevice /PageSize get aload pop 164 2 copy gt {exch} if (Unknown) 165 23 dict 166 dup [612 792] (Letter) put 167 dup [612 1008] (Legal) put 168 dup [595 842] (A4) put 169 {exch aload pop 4 index sub abs 5 le exch 170 5 index sub abs 5 le and 171 {exch pop exit} {pop} ifelse 172 } bind forall = flush pop pop 173 restore" 174</pre> 175 176<p>Query commands can span multiple lines, however no single line may contain more than 255 characters.</p> 177 178<h3><a name='IMPORT'>Importing Existing PPD Files</a></h3> 179 180<P>CUPS includes a utility called <a href='man-ppdi.html'>ppdi(1)</a> 181which allows you to import existing PPD files into the driver information file 182format used by the PPD compiler <a href='man-ppdc.html'>ppdc(1)</a>. Once 183imported, you can modify, localize, and regenerate the PPD files easily. Type 184the following command to import the PPD file <VAR>mydevice.ppd</VAR> into the 185driver information file <VAR>mydevice.drv</VAR>:</P> 186 187<pre class='command'> 188ppdi -o mydevice.drv mydevice.ppd 189</pre> 190 191<P>If you have a whole directory of PPD files that you would like to import, 192you can list multiple filenames or use shell wildcards to import more than one 193PPD file on the command-line:</P> 194 195<pre class='command'> 196ppdi -o mydevice.drv mydevice1.ppd mydevice2.ppd 197ppdi -o mydevice.drv *.ppd 198</pre> 199 200<P>If the driver information file already exists, the new PPD 201file entries are appended to the end of the file. Each PPD file 202is placed in its own group of curly braces within the driver 203information file.</P> 204 205 206<h2 class='title'><a name='FILTERS'>Using Custom Filters</a></h2> 207 208<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> 209 210<pre class='example'> 211<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 0 - 212</pre> 213 214<h3>Custom Command Filters</h3> 215 216<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> 217 218<pre class='example'> 219<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-command 100 /path/to/command/filter 220</pre> 221 222<p>To use the standard PostScript command filter, specify <var>commandtops</var> as the path to the command filter.</p> 223 224<h3>Custom PDF Filters</h3> 225 226<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> 227 228<pre class='example'> 229<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-pdf 100 /path/to/pdf/filter 230</pre> 231 232<p>For unfiltered PDF files, use:</p> 233 234<pre class='example'> 235<a href='ref-ppdcfile.html#Filter'>Filter</a> application/pdf 100 /path/to/pdf/filter 236</pre> 237 238<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> 239 240<h3>Custom PostScript Filters</h3> 241 242<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> 243 244<pre class='example'> 245<a href='ref-ppdcfile.html#Filter'>Filter</a> application/vnd.cups-postscript 100 /path/to/postscript/filter 246</pre> 247 248 249<h2 class='title'><a name='COLOR'>Implementing Color Management</a></h2> 250 251<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> 252 253<pre class='example'> 254<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "ColorModel.MediaType.Resolution/Description" /path/to/ICC/profile 255</pre> 256 257<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> 258 259<pre class='example'> 260<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "Gray../Grayscale Profile" /path/to/ICC/gray-profile 261<a href='ref-ppdcfile.html#Attribute'>Attribute</a> cupsICCProfile "RGB../Full Color Profile" /path/to/ICC/rgb-profile 262</pre> 263 264<p>The options used for profile selection can be customized using the <tt>cupsICCQualifier2</tt> and <tt>cupsICCQualifier3</tt> attributes.</p> 265 266 267<h2 class='title'><a name='MACOSX'>Adding macOS Features</a></h2> 268 269<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> 270 271<pre class='example'> 272<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APDialogExtension "" /Library/Printers/Vendor/filename.plugin 273<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APHelpBook "" /Library/Printers/Vendor/filename.bundle 274<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterIconPath "" /Library/Printers/Vendor/filename.icns 275<a href='ref-ppdcfile.html#Attribute'>Attribute</a> APPrinterPreset "name/text" "*option choice ..." 276</pre> 277
