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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 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	    <para>The selections are used to configure various image
53	    processing functionality performed by the subdevs which affect the
54	    image size. This currently includes cropping, scaling and
55	    composition.</para>
56	
57	    <para>The selection API replaces <link
58	    linkend="vidioc-subdev-g-crop">the old subdev crop API</link>. All
59	    the function of the crop API, and more, are supported by the
60	    selections API.</para>
61	
62	    <para>See <xref linkend="subdev"></xref> for
63	    more information on how each selection target affects the image
64	    processing pipeline inside the subdevice.</para>
65	
66	    <refsect2>
67	      <title>Types of selection targets</title>
68	
69	      <para>There are two types of selection targets: actual and bounds. The
70	      actual targets are the targets which configure the hardware. The BOUNDS
71	      target will return a rectangle that contain all possible actual
72	      rectangles.</para>
73	    </refsect2>
74	
75	    <refsect2>
76	      <title>Discovering supported features</title>
77	
78	      <para>To discover which targets are supported, the user can
79	      perform <constant>VIDIOC_SUBDEV_G_SELECTION</constant> on them.
80	      Any unsupported target will return
81	      <constant>EINVAL</constant>.</para>
82	
83	    <para>Selection targets and flags are documented in <xref
84	    linkend="v4l2-selections-common"/>.</para>
85	
86	    <table pgwide="1" frame="none" id="v4l2-subdev-selection">
87	      <title>struct <structname>v4l2_subdev_selection</structname></title>
88	      <tgroup cols="3">
89	        &cs-str;
90		<tbody valign="top">
91		  <row>
92		    <entry>__u32</entry>
93		    <entry><structfield>which</structfield></entry>
94		    <entry>Active or try selection, from
95		    &v4l2-subdev-format-whence;.</entry>
96		  </row>
97		  <row>
98		    <entry>__u32</entry>
99		    <entry><structfield>pad</structfield></entry>
100		    <entry>Pad number as reported by the media framework.</entry>
101		  </row>
102		  <row>
103		    <entry>__u32</entry>
104		    <entry><structfield>target</structfield></entry>
105		    <entry>Target selection rectangle. See
106		    <xref linkend="v4l2-selections-common" />.</entry>
107		  </row>
108		  <row>
109		    <entry>__u32</entry>
110		    <entry><structfield>flags</structfield></entry>
111		    <entry>Flags. See
112		    <xref linkend="v4l2-selection-flags" />.</entry>
113		  </row>
114		  <row>
115		    <entry>&v4l2-rect;</entry>
116		    <entry><structfield>r</structfield></entry>
117		    <entry>Selection rectangle, in pixels.</entry>
118		  </row>
119		  <row>
120		    <entry>__u32</entry>
121		    <entry><structfield>reserved</structfield>[8]</entry>
122		    <entry>Reserved for future extensions. Applications and drivers must
123		    set the array to zero.</entry>
124		  </row>
125		</tbody>
126	      </tgroup>
127	    </table>
128	    </refsect2>
129	
130	  </refsect1>
131	
132	  <refsect1>
133	    &return-value;
134	
135	    <variablelist>
136	      <varlistentry>
137		<term><errorcode>EBUSY</errorcode></term>
138		<listitem>
139		  <para>The selection rectangle can't be changed because the
140		  pad is currently busy. This can be caused, for instance, by
141		  an active video stream on the pad. The ioctl must not be
142		  retried without performing another action to fix the problem
143		  first. Only returned by
144		  <constant>VIDIOC_SUBDEV_S_SELECTION</constant></para>
145		</listitem>
146	      </varlistentry>
147	      <varlistentry>
148		<term><errorcode>EINVAL</errorcode></term>
149		<listitem>
150		  <para>The &v4l2-subdev-selection;
151		  <structfield>pad</structfield> references a non-existing
152		  pad, the <structfield>which</structfield> field references a
153		  non-existing format, or the selection target is not
154		  supported on the given subdev pad.</para>
155		</listitem>
156	      </varlistentry>
157	    </variablelist>
158	  </refsect1>
159	</refentry>
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