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Based on kernel version 3.13. Page generated on 2014-01-20 22:02 EST.

1	<refentry id="vidioc-subdev-g-selection">
2	  <refmeta>
3	    <refentrytitle>ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION</refentrytitle>
4	    &manvol;
5	  </refmeta>
6	
7	  <refnamediv>
8	    <refname>VIDIOC_SUBDEV_G_SELECTION</refname>
9	    <refname>VIDIOC_SUBDEV_S_SELECTION</refname>
10	    <refpurpose>Get or set selection rectangles on a subdev pad</refpurpose>
11	  </refnamediv>
12	
13	  <refsynopsisdiv>
14	    <funcsynopsis>
15	      <funcprototype>
16		<funcdef>int <function>ioctl</function></funcdef>
17		<paramdef>int <parameter>fd</parameter></paramdef>
18		<paramdef>int <parameter>request</parameter></paramdef>
19		<paramdef>struct v4l2_subdev_selection *<parameter>argp</parameter></paramdef>
20	      </funcprototype>
21	    </funcsynopsis>
22	  </refsynopsisdiv>
23	
24	  <refsect1>
25	    <title>Arguments</title>
26	
27	    <variablelist>
28	      <varlistentry>
29		<term><parameter>fd</parameter></term>
30		<listitem>
31		  <para>&fd;</para>
32		</listitem>
33	      </varlistentry>
34	      <varlistentry>
35		<term><parameter>request</parameter></term>
36		<listitem>
37		  <para>VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION</para>
38		</listitem>
39	      </varlistentry>
40	      <varlistentry>
41		<term><parameter>argp</parameter></term>
42		<listitem>
43		  <para></para>
44		</listitem>
45	      </varlistentry>
46	    </variablelist>
47	  </refsect1>
48	
49	  <refsect1>
50	    <title>Description</title>
51	
52	    <note>
53	      <title>Experimental</title>
54	      <para>This is an <link linkend="experimental">experimental</link>
55	      interface and may change in the future.</para>
56	    </note>
57	
58	    <para>The selections are used to configure various image
59	    processing functionality performed by the subdevs which affect the
60	    image size. This currently includes cropping, scaling and
61	    composition.</para>
62	
63	    <para>The selection API replaces <link
64	    linkend="vidioc-subdev-g-crop">the old subdev crop API</link>. All
65	    the function of the crop API, and more, are supported by the
66	    selections API.</para>
67	
68	    <para>See <xref linkend="subdev"></xref> for
69	    more information on how each selection target affects the image
70	    processing pipeline inside the subdevice.</para>
71	
72	    <refsect2>
73	      <title>Types of selection targets</title>
74	
75	      <para>There are two types of selection targets: actual and bounds. The
76	      actual targets are the targets which configure the hardware. The BOUNDS
77	      target will return a rectangle that contain all possible actual
78	      rectangles.</para>
79	    </refsect2>
80	
81	    <refsect2>
82	      <title>Discovering supported features</title>
83	
84	      <para>To discover which targets are supported, the user can
85	      perform <constant>VIDIOC_SUBDEV_G_SELECTION</constant> on them.
86	      Any unsupported target will return
87	      <constant>EINVAL</constant>.</para>
88	
89	    <para>Selection targets and flags are documented in <xref
90	    linkend="v4l2-selections-common"/>.</para>
91	
92	    <table pgwide="1" frame="none" id="v4l2-subdev-selection">
93	      <title>struct <structname>v4l2_subdev_selection</structname></title>
94	      <tgroup cols="3">
95	        &cs-str;
96		<tbody valign="top">
97		  <row>
98		    <entry>__u32</entry>
99		    <entry><structfield>which</structfield></entry>
100		    <entry>Active or try selection, from
101		    &v4l2-subdev-format-whence;.</entry>
102		  </row>
103		  <row>
104		    <entry>__u32</entry>
105		    <entry><structfield>pad</structfield></entry>
106		    <entry>Pad number as reported by the media framework.</entry>
107		  </row>
108		  <row>
109		    <entry>__u32</entry>
110		    <entry><structfield>target</structfield></entry>
111		    <entry>Target selection rectangle. See
112		    <xref linkend="v4l2-selections-common" />.</entry>
113		  </row>
114		  <row>
115		    <entry>__u32</entry>
116		    <entry><structfield>flags</structfield></entry>
117		    <entry>Flags. See
118		    <xref linkend="v4l2-selection-flags" />.</entry>
119		  </row>
120		  <row>
121		    <entry>&v4l2-rect;</entry>
122		    <entry><structfield>rect</structfield></entry>
123		    <entry>Selection rectangle, in pixels.</entry>
124		  </row>
125		  <row>
126		    <entry>__u32</entry>
127		    <entry><structfield>reserved</structfield>[8]</entry>
128		    <entry>Reserved for future extensions. Applications and drivers must
129		    set the array to zero.</entry>
130		  </row>
131		</tbody>
132	      </tgroup>
133	    </table>
134	    </refsect2>
135	
136	  </refsect1>
137	
138	  <refsect1>
139	    &return-value;
140	
141	    <variablelist>
142	      <varlistentry>
143		<term><errorcode>EBUSY</errorcode></term>
144		<listitem>
145		  <para>The selection rectangle can't be changed because the
146		  pad is currently busy. This can be caused, for instance, by
147		  an active video stream on the pad. The ioctl must not be
148		  retried without performing another action to fix the problem
149		  first. Only returned by
150		  <constant>VIDIOC_SUBDEV_S_SELECTION</constant></para>
151		</listitem>
152	      </varlistentry>
153	      <varlistentry>
154		<term><errorcode>EINVAL</errorcode></term>
155		<listitem>
156		  <para>The &v4l2-subdev-selection;
157		  <structfield>pad</structfield> references a non-existing
158		  pad, the <structfield>which</structfield> field references a
159		  non-existing format, or the selection target is not
160		  supported on the given subdev pad.</para>
161		</listitem>
162	      </varlistentry>
163	    </variablelist>
164	  </refsect1>
165	</refentry>
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