222 lines
8.8 KiB
Plaintext
222 lines
8.8 KiB
Plaintext
<!--
|
||
PPD API introduction for CUPS.
|
||
|
||
Copyright © 2007-2019 by Apple Inc.
|
||
Copyright © 1997-2006 by Easy Software Products, all rights reserved.
|
||
|
||
Licensed under Apache License v2.0. See the file "LICENSE" for more
|
||
information.
|
||
-->
|
||
|
||
<h2 class='title'><a name='OVERVIEW'>Overview</a></h2>
|
||
|
||
<blockquote><b>Note:</b>
|
||
|
||
<p>The PPD API was deprecated in CUPS 1.6/macOS 10.8. Please use the new Job Ticket APIs in the <a href="cupspm.html">CUPS Programming Manual</a> documentation. These functions will be removed in a future release of CUPS.</p>
|
||
</blockquote>
|
||
|
||
<p>The CUPS PPD API provides read-only access the data in PostScript Printer
|
||
Description ("PPD") files which are used for all printers with a driver. With
|
||
it you can obtain the data necessary to display printer options to users, mark
|
||
option choices and check for conflicting choices, and output marked choices in
|
||
PostScript output. The <a href="#ppd_file_t"><code>ppd_file_t</code></a>
|
||
structure contains all of the information in a PPD file.</p>
|
||
|
||
<blockquote><b>Note:</b>
|
||
|
||
<p>The CUPS PPD API uses the terms "option" and "choice" instead of the Adobe
|
||
terms "MainKeyword" and "OptionKeyword" to refer to specific printer options and
|
||
features. CUPS also treats option ("MainKeyword") and choice ("OptionKeyword")
|
||
values as case-insensitive strings, so option "InputSlot" and choice "Upper"
|
||
are equivalent to "inputslot" and "upper", respectively.</p>
|
||
</blockquote>
|
||
|
||
|
||
<h3><a name="LOADING">Loading a PPD File</a></h3>
|
||
|
||
<p>The <a href="#ppdOpenFile"><code>ppdOpenFile</code></a> function "opens" a
|
||
PPD file and loads it into memory. For example, the following code opens the
|
||
current printer's PPD file in a CUPS filter:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd = <a href="#ppdOpenFile">ppdOpenFile</a>(getenv("PPD"));
|
||
</pre>
|
||
|
||
<p>The return value is a pointer to a new
|
||
<a href="#ppd_file_t"><code>ppd_file_t</code></a> structure or <code>NULL</code>
|
||
if the PPD file does not exist or cannot be loaded. The
|
||
<a href="#ppdClose"><code>ppdClose</code></a> function frees the memory used
|
||
by the structure:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
|
||
<a href="#ppdClose">ppdClose</a>(ppd);
|
||
</pre>
|
||
|
||
<p>Once closed, pointers to the <a href="#ppd_file_t"><code>ppd_file_t</code></a>
|
||
structure and any data in it will no longer be valid.</p>
|
||
|
||
<h3><a name="OPTIONS_AND_GROUPS">Options and Groups</a></h3>
|
||
|
||
<p>PPD files support multiple options, which are stored in arrays of
|
||
<a href="#ppd_option_t"><code>ppd_option_t</code></a> and
|
||
<a href="#ppd_choice_t"><code>ppd_choice_t</code></a> structures.</p>
|
||
|
||
<p>Each option in turn is associated with a group stored in a
|
||
<a href="#ppd_group_t"><code>ppd_group_t</code></a> structure. Groups can be
|
||
specified in the PPD file; if an option is not associated with a group
|
||
then it is put in an automatically-generated "General" group. Groups can also
|
||
have sub-groups, however CUPS currently ignores sub-groups because of past
|
||
abuses of this functionality.</p>
|
||
|
||
<p>Option choices are selected by marking them using one of three functions. The
|
||
first is <a href="#ppdMarkDefaults"><code>ppdMarkDefaults</code></a> which
|
||
selects all of the default options in the PPD file:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
|
||
<a href="#ppdMarkDefaults">ppdMarkDefaults</a>(ppd);
|
||
</pre>
|
||
|
||
<p>The second is <a href="#ppdMarkOption"><code>ppdMarkOption</code></a>
|
||
which selects a single option choice in the PPD file. For example, the following
|
||
code selects the upper paper tray:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
|
||
<a href="#ppdMarkOption">ppdMarkOption</a>(ppd, "InputSlot", "Upper");
|
||
</pre>
|
||
|
||
<p>The last function is
|
||
<a href="#cupsMarkOptions"><code>cupsMarkOptions</code></a> which selects
|
||
multiple option choices in the PPD file from an array of CUPS options, mapping
|
||
IPP attributes like "media" and "sides" to their corresponding PPD options. You
|
||
typically use this function in a print filter with
|
||
<code>cupsParseOptions</code> and
|
||
<a href="#ppdMarkDefaults"><code>ppdMarkDefaults</code></a> to select all of
|
||
the option choices needed for the job, for example:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd = <a href="#ppdOpenFile">ppdOpenFile</a>(getenv("PPD"));
|
||
cups_option_t *options = NULL;
|
||
int num_options = cupsParseOptions(argv[5], 0, &options);
|
||
|
||
<a href="#ppdMarkDefaults">ppdMarkDefaults</a>(ppd);
|
||
<a href="#cupsMarkOptions">cupsMarkOptions</a>(ppd, num_options, options);
|
||
cupsFreeOptions(num_options, options);
|
||
</pre>
|
||
|
||
|
||
<h3><a name="CONSTRAINTS">Constraints</a></h3>
|
||
|
||
<p>PPD files support specification of conflict conditions, called
|
||
constraints, between different options. Constraints are stored in an array of
|
||
<a href="#ppd_const_t"><code>ppd_const_t</code></a> structures which specify
|
||
the options and choices that conflict with each other. The
|
||
<a href="#ppdConflicts"><code>ppdConflicts</code></a> function tells you
|
||
how many of the selected options are incompatible. Since constraints are
|
||
normally specified in pairs, the returned value is typically an even number.</p>
|
||
|
||
|
||
<h3><a name="PAGE_SIZES">Page Sizes</a></h3>
|
||
|
||
<p>Page sizes are special options which have physical dimensions and margins
|
||
associated with them. The size information is stored in
|
||
<a href="#ppd_size_t"><code>ppd_size_t</code></a> structures and is available
|
||
by looking up the named size with the
|
||
<a href="#ppdPageSize"><code>ppdPageSize</code></a> function. The page size and
|
||
margins are returned in units called points; there are 72 points per inch. If
|
||
you pass <code>NULL</code> for the size, the currently selected size is
|
||
returned:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
<a href="#ppd_size_t">ppd_size_t</a> *size = <a href="#ppdPageSize">ppdPageSize</a>(ppd, NULL);
|
||
</pre>
|
||
|
||
<p>Besides the standard page sizes listed in a PPD file, some printers
|
||
support variable or custom page sizes. Custom page sizes are supported if the
|
||
<code>variables_sizes</code> member of the
|
||
<a href="#ppd_file_t"><code>ppd_file_t</code></a> structure is non-zero.
|
||
The <code>custom_min</code>, <code>custom_max</code>, and
|
||
<code>custom_margins</code> members of the
|
||
<a href="#ppd_file_t"><code>ppd_file_t</code></a> structure define the limits
|
||
of the printable area. To get the resulting media size, use a page size string
|
||
of the form "Custom.<I>width</I>x<I>length</I>", where "width" and "length" are
|
||
in points. Custom page size names can also be specified in inches
|
||
("Custom.<i>width</i>x<i>height</i>in"), centimeters
|
||
("Custom.<i>width</i>x<i>height</i>cm"), or millimeters
|
||
("Custom.<i>width</i>x<i>height</i>mm"):</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
|
||
/* Get an 576x720 point custom page size */
|
||
<a href="#ppd_size_t">ppd_size_t</a> *size = <a href="#ppdPageSize">ppdPageSize</a>(ppd, "Custom.576x720");
|
||
|
||
/* Get an 8x10 inch custom page size */
|
||
<a href="#ppd_size_t">ppd_size_t</a> *size = <a href="#ppdPageSize">ppdPageSize</a>(ppd, "Custom.8x10in");
|
||
|
||
/* Get a 100x200 millimeter custom page size */
|
||
<a href="#ppd_size_t">ppd_size_t</a> *size = <a href="#ppdPageSize">ppdPageSize</a>(ppd, "Custom.100x200mm");
|
||
|
||
/* Get a 12.7x34.5 centimeter custom page size */
|
||
<a href="#ppd_size_t">ppd_size_t</a> *size = <a href="#ppdPageSize">ppdPageSize</a>(ppd, "Custom.12.7x34.5cm");
|
||
</pre>
|
||
|
||
<p>If the PPD does not support variable page sizes, the
|
||
<a href="#ppdPageSize"><code>ppdPageSize</code></a> function will return
|
||
<code>NULL</code>.</p>
|
||
|
||
|
||
<h3><a name="ATTRIBUTES">Attributes</a></h3>
|
||
|
||
<p>Every PPD file is composed of one or more attributes. Most of these
|
||
attributes are used to define groups, options, choices, and page sizes,
|
||
however several informational attributes may be present which you can access
|
||
in your program or filter. Attributes normally look like one of the following
|
||
examples in a PPD file:</p>
|
||
|
||
<pre class="example">
|
||
*name: "value"
|
||
*name spec: "value"
|
||
*name spec/text: "value"
|
||
</pre>
|
||
|
||
<p>The <a href="#ppdFindAttr"><code>ppdFindAttr</code></a> and
|
||
<a href="#ppdFindNextAttr"><code>ppdFindNextAttr</code></a> functions find the
|
||
first and next instances, respectively, of the named attribute with the given
|
||
"spec" string and return a <a href="#ppd_attr_t"><code>ppd_attr_t</code></a>
|
||
structure. If you provide a NULL specifier string, all attributes with the
|
||
given name will be returned. For example, the following code lists all of the
|
||
<code>Product</code> attributes in a PPD file:</p>
|
||
|
||
<pre class="example">
|
||
#include <cups/ppd.h>
|
||
|
||
<a href="#ppd_file_t">ppd_file_t</a> *ppd;
|
||
<a href="#ppd_attr_t">ppd_attr_t</a> *attr;
|
||
|
||
for (attr = <a href="#ppdFindAttr">ppdFindAttr</a>(ppd, "Product", NULL);
|
||
attr != NULL;
|
||
attr = <a href="#ppdFindNextAttr">ppdFindNextAttr</a>(ppd, "Product", NULL))
|
||
puts(attr->value);
|
||
</pre>
|