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Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-subdev-g-crop.xml')
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diff --git a/Documentation/DocBook/media/v4l/vidioc-subdev-g-crop.xml b/Documentation/DocBook/media/v4l/vidioc-subdev-g-crop.xml new file mode 100644 index 0000000..0619732 --- /dev/null +++ b/Documentation/DocBook/media/v4l/vidioc-subdev-g-crop.xml @@ -0,0 +1,155 @@ +<refentry id="vidioc-subdev-g-crop"> + <refmeta> + <refentrytitle>ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_SUBDEV_G_CROP</refname> + <refname>VIDIOC_SUBDEV_S_CROP</refname> + <refpurpose>Get or set the crop rectangle on a subdev pad</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + <para>This is an <link linkend="experimental">experimental</link> + interface and may change in the future.</para> + </note> + + <para>To retrieve the current crop rectangle applications set the + <structfield>pad</structfield> field of a &v4l2-subdev-crop; to the + desired pad number as reported by the media API and the + <structfield>which</structfield> field to + <constant>V4L2_SUBDEV_FORMAT_ACTIVE</constant>. They then call the + <constant>VIDIOC_SUBDEV_G_CROP</constant> ioctl with a pointer to this + structure. The driver fills the members of the <structfield>rect</structfield> + field or returns &EINVAL; if the input arguments are invalid, or if cropping + is not supported on the given pad.</para> + + <para>To change the current crop rectangle applications set both the + <structfield>pad</structfield> and <structfield>which</structfield> fields + and all members of the <structfield>rect</structfield> field. They then call + the <constant>VIDIOC_SUBDEV_S_CROP</constant> ioctl with a pointer to this + structure. The driver verifies the requested crop rectangle, adjusts it + based on the hardware capabilities and configures the device. Upon return + the &v4l2-subdev-crop; contains the current format as would be returned + by a <constant>VIDIOC_SUBDEV_G_CROP</constant> call.</para> + + <para>Applications can query the device capabilities by setting the + <structfield>which</structfield> to + <constant>V4L2_SUBDEV_FORMAT_TRY</constant>. When set, 'try' crop + rectangles are not applied to the device by the driver, but are mangled + exactly as active crop rectangles and stored in the sub-device file handle. + Two applications querying the same sub-device would thus not interact with + each other.</para> + + <para>Drivers must not return an error solely because the requested crop + rectangle doesn't match the device capabilities. They must instead modify + the rectangle to match what the hardware can provide. The modified format + should be as close as possible to the original request.</para> + + <table pgwide="1" frame="none" id="v4l2-subdev-crop"> + <title>struct <structname>v4l2_subdev_crop</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>pad</structfield></entry> + <entry>Pad number as reported by the media framework.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>which</structfield></entry> + <entry>Crop rectangle to get or set, from + &v4l2-subdev-format-whence;.</entry> + </row> + <row> + <entry>&v4l2-rect;</entry> + <entry><structfield>rect</structfield></entry> + <entry>Crop rectangle boundaries, in pixels.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry>Reserved for future extensions. Applications and drivers must + set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The crop rectangle can't be changed because the pad is currently + busy. This can be caused, for instance, by an active video stream on + the pad. The ioctl must not be retried without performing another + action to fix the problem first. Only returned by + <constant>VIDIOC_SUBDEV_S_CROP</constant></para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-subdev-crop; <structfield>pad</structfield> + references a non-existing pad, the <structfield>which</structfield> + field references a non-existing format, or cropping is not supported + on the given subdev pad.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> |