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<section id="v4l2-selections-common">
<title>Common selection definitions</title>
<para>While the <link linkend="selection-api">V4L2 selection
API</link> and <link linkend="v4l2-subdev-selections">V4L2 subdev
selection APIs</link> are very similar, there's one fundamental
difference between the two. On sub-device API, the selection
rectangle refers to the media bus format, and is bound to a
sub-device's pad. On the V4L2 interface the selection rectangles
refer to the in-memory pixel format.</para>
<para>This section defines the common definitions of the
selection interfaces on the two APIs.</para>
<section id="v4l2-selection-targets">
<title>Selection targets</title>
<para>The precise meaning of the selection targets may be
dependent on which of the two interfaces they are used.</para>
<table pgwide="1" frame="none" id="v4l2-selection-targets-table">
<title>Selection target definitions</title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
&cs-def;
<thead>
<row rowsep="1">
<entry align="left">Target name</entry>
<entry align="left">id</entry>
<entry align="left">Definition</entry>
<entry align="left">Valid for V4L2</entry>
<entry align="left">Valid for V4L2 subdev</entry>
</row>
</thead>
<tbody valign="top">
<row>
<entry><constant>V4L2_SEL_TGT_CROP</constant></entry>
<entry>0x0000</entry>
<entry>Crop rectangle. Defines the cropped area.</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_CROP_DEFAULT</constant></entry>
<entry>0x0001</entry>
<entry>Suggested cropping rectangle that covers the "whole picture".</entry>
<entry>Yes</entry>
<entry>No</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_CROP_BOUNDS</constant></entry>
<entry>0x0002</entry>
<entry>Bounds of the crop rectangle. All valid crop
rectangles fit inside the crop bounds rectangle.
</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_NATIVE_SIZE</constant></entry>
<entry>0x0003</entry>
<entry>The native size of the device, e.g. a sensor's
pixel array. <structfield>left</structfield> and
<structfield>top</structfield> fields are zero for this
target. Setting the native size will generally only make
sense for memory to memory devices where the software can
create a canvas of a given size in which for example a
video frame can be composed. In that case
V4L2_SEL_TGT_NATIVE_SIZE can be used to configure the size
of that canvas.
</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_COMPOSE</constant></entry>
<entry>0x0100</entry>
<entry>Compose rectangle. Used to configure scaling
and composition.</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_DEFAULT</constant></entry>
<entry>0x0101</entry>
<entry>Suggested composition rectangle that covers the "whole picture".</entry>
<entry>Yes</entry>
<entry>No</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_BOUNDS</constant></entry>
<entry>0x0102</entry>
<entry>Bounds of the compose rectangle. All valid compose
rectangles fit inside the compose bounds rectangle.</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_TGT_COMPOSE_PADDED</constant></entry>
<entry>0x0103</entry>
<entry>The active area and all padding pixels that are inserted or
modified by hardware.</entry>
<entry>Yes</entry>
<entry>No</entry>
</row>
</tbody>
</tgroup>
</table>
</section>
<section id="v4l2-selection-flags">
<title>Selection flags</title>
<table pgwide="1" frame="none" id="v4l2-selection-flags-table">
<title>Selection flag definitions</title>
<tgroup cols="5">
<colspec colname="c1" />
<colspec colname="c2" />
<colspec colname="c3" />
<colspec colname="c4" />
<colspec colname="c5" />
&cs-def;
<thead>
<row rowsep="1">
<entry align="left">Flag name</entry>
<entry align="left">id</entry>
<entry align="left">Definition</entry>
<entry align="left">Valid for V4L2</entry>
<entry align="left">Valid for V4L2 subdev</entry>
</row>
</thead>
<tbody valign="top">
<row>
<entry><constant>V4L2_SEL_FLAG_GE</constant></entry>
<entry>(1 &lt;&lt; 0)</entry>
<entry>Suggest the driver it should choose greater or
equal rectangle (in size) than was requested. Albeit the
driver may choose a lesser size, it will only do so due to
hardware limitations. Without this flag (and
<constant>V4L2_SEL_FLAG_LE</constant>) the
behaviour is to choose the closest possible
rectangle.</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_FLAG_LE</constant></entry>
<entry>(1 &lt;&lt; 1)</entry>
<entry>Suggest the driver it
should choose lesser or equal rectangle (in size) than was
requested. Albeit the driver may choose a greater size, it
will only do so due to hardware limitations.</entry>
<entry>Yes</entry>
<entry>Yes</entry>
</row>
<row>
<entry><constant>V4L2_SEL_FLAG_KEEP_CONFIG</constant></entry>
<entry>(1 &lt;&lt; 2)</entry>
<entry>The configuration must not be propagated to any
further processing steps. If this flag is not given, the
configuration is propagated inside the subdevice to all
further processing steps.</entry>
<entry>No</entry>
<entry>Yes</entry>
</row>
</tbody>
</tgroup>
</table>
</section>
</section>