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Based on kernel version 4.1. Page generated on 2015-06-28 12:12 EST.

1	<section id="v4l2-selections-common">
2	
3	  <title>Common selection definitions</title>
4	
5	  <para>While the <link linkend="selection-api">V4L2 selection
6	  API</link> and <link linkend="v4l2-subdev-selections">V4L2 subdev
7	  selection APIs</link> are very similar, there's one fundamental
8	  difference between the two. On sub-device API, the selection
9	  rectangle refers to the media bus format, and is bound to a
10	  sub-device's pad. On the V4L2 interface the selection rectangles
11	  refer to the in-memory pixel format.</para>
12	
13	  <para>This section defines the common definitions of the
14	  selection interfaces on the two APIs.</para>
15	
16	  <section id="v4l2-selection-targets">
17	
18	    <title>Selection targets</title>
19	
20	    <para>The precise meaning of the selection targets may be
21	    dependent on which of the two interfaces they are used.</para>
22	
23	    <table pgwide="1" frame="none" id="v4l2-selection-targets-table">
24	    <title>Selection target definitions</title>
25	      <tgroup cols="5">
26		<colspec colname="c1" />
27		<colspec colname="c2" />
28		<colspec colname="c3" />
29		<colspec colname="c4" />
30		<colspec colname="c5" />
31		&cs-def;
32		<thead>
33		  <row rowsep="1">
34		    <entry align="left">Target name</entry>
35		    <entry align="left">id</entry>
36		    <entry align="left">Definition</entry>
37		    <entry align="left">Valid for V4L2</entry>
38		    <entry align="left">Valid for V4L2 subdev</entry>
39		  </row>
40		</thead>
41		<tbody valign="top">
42		  <row>
43		    <entry><constant>V4L2_SEL_TGT_CROP</constant></entry>
44		    <entry>0x0000</entry>
45		    <entry>Crop rectangle. Defines the cropped area.</entry>
46		    <entry>Yes</entry>
47		    <entry>Yes</entry>
48		  </row>
49		  <row>
50		    <entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry>
51		    <entry>0x0001</entry>
52		    <entry>Suggested cropping rectangle that covers the "whole picture".</entry>
53		    <entry>Yes</entry>
54		    <entry>No</entry>
55		  </row>
56		  <row>
57		    <entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry>
58		    <entry>0x0002</entry>
59		    <entry>Bounds of the crop rectangle. All valid crop
60		    rectangles fit inside the crop bounds rectangle.
61		    </entry>
62		    <entry>Yes</entry>
63		    <entry>Yes</entry>
64		  </row>
65		  <row>
66		    <entry><constant>V4L2_SEL_TGT_NATIVE_SIZE</constant></entry>
67		    <entry>0x0003</entry>
68		    <entry>The native size of the device, e.g. a sensor's
69		    pixel array. <structfield>left</structfield> and
70		    <structfield>top</structfield> fields are zero for this
71		    target. Setting the native size will generally only make
72		    sense for memory to memory devices where the software can
73		    create a canvas of a given size in which for example a
74		    video frame can be composed. In that case
75		    V4L2_SEL_TGT_NATIVE_SIZE can be used to configure the size
76		    of that canvas.
77		    </entry>
78		    <entry>Yes</entry>
79		    <entry>Yes</entry>
80		  </row>
81		  <row>
82		    <entry><constant>V4L2_SEL_TGT_COMPOSE</constant></entry>
83		    <entry>0x0100</entry>
84		    <entry>Compose rectangle. Used to configure scaling
85		    and composition.</entry>
86		    <entry>Yes</entry>
87		    <entry>Yes</entry>
88		  </row>
89		  <row>
90		    <entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry>
91		    <entry>0x0101</entry>
92		    <entry>Suggested composition rectangle that covers the "whole picture".</entry>
93		    <entry>Yes</entry>
94		    <entry>No</entry>
95		  </row>
96		  <row>
97		    <entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry>
98		    <entry>0x0102</entry>
99		    <entry>Bounds of the compose rectangle. All valid compose
100		    rectangles fit inside the compose bounds rectangle.</entry>
101		    <entry>Yes</entry>
102		    <entry>Yes</entry>
103		  </row>
104		  <row>
105		    <entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry>
106		    <entry>0x0103</entry>
107		    <entry>The active area and all padding pixels that are inserted or
108		    modified by hardware.</entry>
109		    <entry>Yes</entry>
110		    <entry>No</entry>
111		  </row>
112		</tbody>
113	      </tgroup>
114	    </table>
115	
116	  </section>
117	
118	  <section id="v4l2-selection-flags">
119	
120	    <title>Selection flags</title>
121	
122	    <table pgwide="1" frame="none" id="v4l2-selection-flags-table">
123	    <title>Selection flag definitions</title>
124	      <tgroup cols="5">
125		<colspec colname="c1" />
126		<colspec colname="c2" />
127		<colspec colname="c3" />
128		<colspec colname="c4" />
129		<colspec colname="c5" />
130		&cs-def;
131		<thead>
132		<row rowsep="1">
133		    <entry align="left">Flag name</entry>
134		    <entry align="left">id</entry>
135		    <entry align="left">Definition</entry>
136		    <entry align="left">Valid for V4L2</entry>
137		    <entry align="left">Valid for V4L2 subdev</entry>
138		</row>
139		</thead>
140		<tbody valign="top">
141		  <row>
142		    <entry><constant>V4L2_SEL_FLAG_GE</constant></entry>
143		    <entry>(1 &lt;&lt; 0)</entry>
144		    <entry>Suggest the driver it should choose greater or
145		    equal rectangle (in size) than was requested. Albeit the
146		    driver may choose a lesser size, it will only do so due to
147		    hardware limitations. Without this flag (and
148		    <constant>V4L2_SEL_FLAG_LE</constant>) the
149		    behaviour is to choose the closest possible
150		    rectangle.</entry>
151		    <entry>Yes</entry>
152		    <entry>Yes</entry>
153		  </row>
154		  <row>
155		    <entry><constant>V4L2_SEL_FLAG_LE</constant></entry>
156		    <entry>(1 &lt;&lt; 1)</entry>
157		    <entry>Suggest the driver it
158		    should choose lesser or equal rectangle (in size) than was
159		    requested. Albeit the driver may choose a greater size, it
160		    will only do so due to hardware limitations.</entry>
161		    <entry>Yes</entry>
162		    <entry>Yes</entry>
163		  </row>
164		  <row>
165		    <entry><constant>V4L2_SEL_FLAG_KEEP_CONFIG</constant></entry>
166		    <entry>(1 &lt;&lt; 2)</entry>
167		    <entry>The configuration must not be propagated to any
168		    further processing steps. If this flag is not given, the
169		    configuration is propagated inside the subdevice to all
170		    further processing steps.</entry>
171		    <entry>No</entry>
172		    <entry>Yes</entry>
173		  </row>
174		</tbody>
175	      </tgroup>
176	    </table>
177	
178	  </section>
179	
180	</section>
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