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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-21 09:03:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-21 09:03:10 -0700
commitc720f5655df159a630fa0290a0bd67c93e92b0bf (patch)
tree940d139d0ec1ff5201efddef6cc663166a8a2df3 /Documentation/DocBook/v4l/vidioc-g-crop.xml
parent33e6c1a0de818d3698cdab27c42915661011319d (diff)
parent84d6ae431f315e8973aac3c3fe1d550fc9240ef3 (diff)
Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (222 commits) V4L/DVB (13033): pt1: Don't use a deprecated DMA_BIT_MASK macro V4L/DVB (13029): radio-si4713: remove #include <linux/version.h> V4L/DVB (13027): go7007: convert printks to v4l2_info V4L/DVB (13026): s2250-board: Implement brightness and contrast controls V4L/DVB (13025): s2250-board: Fix memory leaks V4L/DVB (13024): go7007: Implement vidioc_g_std and vidioc_querystd V4L/DVB (13023): go7007: Merge struct gofh and go declarations V4L/DVB (13022): go7007: Fix mpeg controls V4L/DVB (13021): go7007: Fix whitespace and line lengths V4L/DVB (13020): go7007: Updates to Kconfig and Makefile V4L/DVB (13019): video: initial support for ADV7180 V4L/DVB (13018): kzalloc failure ignored in au8522_probe() V4L/DVB (13017): gspca: kmalloc failure ignored in sd_start() V4L/DVB (13016): kmalloc failure ignored in lgdt3304_attach() and s921_attach() V4L/DVB (13015): kmalloc failure ignored in m920x_firmware_download() V4L/DVB (13014): Add support for Compro VideoMate E800 (DVB-T part only) V4L/DVB (13013): FM TX: si4713: Kconfig: Fixed two typos. V4L/DVB (13012): uvc: introduce missing kfree V4L/DVB (13011): Change tuner type of BeholdTV cards V4L/DVB (13009): gspca - stv06xx-hdcs: Reduce exposure range ...
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+<refentry id="vidioc-g-crop">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_G_CROP, VIDIOC_S_CROP</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_G_CROP</refname>
+ <refname>VIDIOC_S_CROP</refname>
+ <refpurpose>Get or set the current cropping rectangle</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_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_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_G_CROP, VIDIOC_S_CROP</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>To query the cropping rectangle size and position
+applications set the <structfield>type</structfield> field of a
+<structname>v4l2_crop</structname> structure to the respective buffer
+(stream) type and call the <constant>VIDIOC_G_CROP</constant> ioctl
+with a pointer to this structure. The driver fills the rest of the
+structure or returns the &EINVAL; if cropping is not supported.</para>
+
+ <para>To change the cropping rectangle applications initialize the
+<structfield>type</structfield> and &v4l2-rect; substructure named
+<structfield>c</structfield> of a v4l2_crop structure and call the
+<constant>VIDIOC_S_CROP</constant> ioctl with a pointer to this
+structure.</para>
+
+ <para>The driver first adjusts the requested dimensions against
+hardware limits, &ie; the bounds given by the capture/output window,
+and it rounds to the closest possible values of horizontal and
+vertical offset, width and height. In particular the driver must round
+the vertical offset of the cropping rectangle to frame lines modulo
+two, such that the field order cannot be confused.</para>
+
+ <para>Second the driver adjusts the image size (the opposite
+rectangle of the scaling process, source or target depending on the
+data direction) to the closest size possible while maintaining the
+current horizontal and vertical scaling factor.</para>
+
+ <para>Finally the driver programs the hardware with the actual
+cropping and image parameters. <constant>VIDIOC_S_CROP</constant> is a
+write-only ioctl, it does not return the actual parameters. To query
+them applications must call <constant>VIDIOC_G_CROP</constant> and
+&VIDIOC-G-FMT;. When the parameters are unsuitable the application may
+modify the cropping or image parameters and repeat the cycle until
+satisfactory parameters have been negotiated.</para>
+
+ <para>When cropping is not supported then no parameters are
+changed and <constant>VIDIOC_S_CROP</constant> returns the
+&EINVAL;.</para>
+
+ <table pgwide="1" frame="none" id="v4l2-crop">
+ <title>struct <structname>v4l2_crop</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>&v4l2-buf-type;</entry>
+ <entry><structfield>type</structfield></entry>
+ <entry>Type of the data stream, set by the application.
+Only these types are valid here: <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>,
+<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>,
+<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver
+defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant>
+and higher.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-rect;</entry>
+ <entry><structfield>c</structfield></entry>
+ <entry>Cropping rectangle. The same co-ordinate system as
+for &v4l2-cropcap; <structfield>bounds</structfield> is used.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>Cropping is not supported.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->