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<div align='justify'>
<h1 align="right"><a name='PS_DRIVERS'>4 - Developing PostScript
Printer Drivers</a></h1>
<p>This chapter describes how to develop PPD files for
PostScript printer drivers.</p>
<h2>Overview of PostScript Driver Development</h2>
<p>The PPD compiler is capable of producing PPD files for
PostScript printers just as easily as for non-PostScript
printers. PostScript printer drivers use the <tt>ps</tt> driver
type:</p>
<pre>
DriverType ps
</pre>
<h3>Required Attributes</h3>
<p>PostScript drivers require the attributes listed in <a
href='#TABLE4-1'>Table 4-1</a>. If not specified, the defaults
for CUPS drivers are used. A typical PostScript driver
information file would include the following attributes:</p>
<pre>
Attribute DefaultColorSpace "" Gray
Attribute LandscapeOrientation "" Minus90
Attribute LanguageLevel "" "3"
Attribute Product "" "(Foo LaserProofer 2000)"
Attribute PSVersion "" "(3010) 0"
Attribute TTRasterizer "" Type42
</pre>
<!-- NEW PAGE -->
<center><table border='1' cellpadding='5' cellspacing='0' width='90%'>
<caption align='bottom'><a name='TABLE4-1'><i>Table 4-1,
Required PostScript printer driver attributes</i></a></caption>
<tr bgcolor='#cccccc'>
<th>Attribute</th>
<th>Description</th>
</tr>
<tr>
<td valign='top'><tt>DefaultColorSpace</tt></td>
<td align='justify' valign='top'>The default colorspace:
<tt>Gray</tt>, <tt>RGB</tt>, <tt>CMY</tt>, or
<tt>CMYK</tt>. If not specified, then <tt>RGB</tt> is
assumed.</td>
</tr>
<tr>
<td valign='top'><tt>LandscapeOrientation</tt></td>
<td align='justify' valign='top'>The preferred landscape
orientation: <tt>Plus90</tt>, <tt>Minus90</tt>, or
<tt>Any</tt>. If not specified, <tt>Plus90</tt> is
assumed.</td>
</tr>
<tr>
<td valign='top'><tt>LanguageLevel</tt></td>
<td align='justify' valign='top'>The PostScript language
level supported by the device: 1, 2, or 3. If not
specified, 2 is assumed.</td>
</tr>
<tr>
<td valign='top'><tt>Product</tt></td>
<td align='justify' valign='top'>The string returned by
the PostScript <tt>product</tt> operator, which
<i>must</i> include parenthesis to conform with
PostScript syntax rules for strings. Multiple
<tt>Product</tt> attributes may be specified to support
multiple products with the same PPD file. If not
specified, "(ESP Ghostscript)" and "(GNU Ghostscript)"
are assumed.</td>
</tr>
<tr>
<td valign='top'><tt>PSVersion</tt></td>
<td align='justify' valign='top'>The PostScript
interpreter version numbers as returned by the
<tt>version</tt> and <tt>revision</tt> operators. The
required format is "(version) revision". Multiple
<tt>PSVersion</tt> attributes may be specified to
support multiple interpreter version numbers. If not
specified, "(3010) 705" and "(3010) 707" are
assumed.</td>
</tr>
<tr>
<td valign='top'><tt>TTRasterizer</tt></td>
<td align='justify' valign='top'>The type of TrueType
font rasterizer supported by the device, if any. The
supported values are <tt>None</tt>, <tt>Accept68k</tt>,
<tt>Type42</tt>, and <tt>TrueImage</tt>. If not
specified, <tt>None</tt> is assumed.</td>
</tr>
</table></center>
<h3>Query Commands</h3>
<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 query command for the <tt>PageSize</tt> option
might look like the following:</p>
<pre>
Attribute "?PageSize" "" "
save
currentpagedevice /PageSize get aload pop
2 copy gt {exch} if (Unknown)
23 dict
dup [612 792] (Letter) put
dup [612 1008] (Legal) put
dup [595 842] (A4) put
{exch aload pop 4 index sub abs 5 le exch
5 index sub abs 5 le and
{exch pop exit} {pop} ifelse
} bind forall = flush pop pop
restore"
</pre>
<p>Query commands can span multiple lines, however no single
line may contain more than 255 characters.</p>
<h3>Adding Filters</h3>
<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>
<pre>
Filter application/vnd.cups-postscript 0 -
</pre>
<h2>Importing Existing PostScript Drivers</h2>
<p>The <tt>ppdi(1)</tt> utility included with the CUPS DDK
imports existing PPD files into driver information files. This
allows you to make modifications and localize PPD files for
other languages with great ease. Use the following command to
import a single PPD file called <var>filename.ppd</var> into a
driver information file called <var>filename.drv</var>:</p>
<pre>
<kbd>ppdi filename.drv filename.ppd ENTER</kbd>
</pre>
<p>The driver information file is created if it does not exist.
Otherwise the PPD file information is appended to the end of the
file. You can use shell wildcards to import whole directories of
PPD files:</p>
<pre>
<kbd>ppdi filename.drv *.ppd ENTER</kbd>
</pre>
<p>Once imported, you can edit the driver information file and
use the <tt>ppdc</tt> program to regenerate the PPD files:</p>
<pre>
<kbd>ppdc filename.drv ENTER</kbd>
</pre>
</div>
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