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