linux-vybrid_public/Documentation/DocBook/media/v4l/selections-common.xml

<section id="v4l2-selections-common">

  <title>Selection targets</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>The precise meaning of the selection targets may thus be
  affected 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_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>