Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 EST.
1 <refentry id="vidioc-subdev-g-crop"> 2 <refmeta> 3 <refentrytitle>ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</refentrytitle> 4 &manvol; 5 </refmeta> 6 7 <refnamediv> 8 <refname>VIDIOC_SUBDEV_G_CROP</refname> 9 <refname>VIDIOC_SUBDEV_S_CROP</refname> 10 <refpurpose>Get or set the crop rectangle on a subdev pad</refpurpose> 11 </refnamediv> 12 13 <refsynopsisdiv> 14 <funcsynopsis> 15 <funcprototype> 16 <funcdef>int <function>ioctl</function></funcdef> 17 <paramdef>int <parameter>fd</parameter></paramdef> 18 <paramdef>int <parameter>request</parameter></paramdef> 19 <paramdef>struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> 20 </funcprototype> 21 </funcsynopsis> 22 <funcsynopsis> 23 <funcprototype> 24 <funcdef>int <function>ioctl</function></funcdef> 25 <paramdef>int <parameter>fd</parameter></paramdef> 26 <paramdef>int <parameter>request</parameter></paramdef> 27 <paramdef>const struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> 28 </funcprototype> 29 </funcsynopsis> 30 </refsynopsisdiv> 31 32 <refsect1> 33 <title>Arguments</title> 34 35 <variablelist> 36 <varlistentry> 37 <term><parameter>fd</parameter></term> 38 <listitem> 39 <para>&fd;</para> 40 </listitem> 41 </varlistentry> 42 <varlistentry> 43 <term><parameter>request</parameter></term> 44 <listitem> 45 <para>VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</para> 46 </listitem> 47 </varlistentry> 48 <varlistentry> 49 <term><parameter>argp</parameter></term> 50 <listitem> 51 <para></para> 52 </listitem> 53 </varlistentry> 54 </variablelist> 55 </refsect1> 56 57 <refsect1> 58 <title>Description</title> 59 60 <note> 61 <title>Experimental</title> 62 <para>This is an <link linkend="experimental">experimental</link> 63 interface and may change in the future.</para> 64 </note> 65 66 <para>To retrieve the current crop rectangle applications set the 67 <structfield>pad</structfield> field of a &v4l2-subdev-crop; to the 68 desired pad number as reported by the media API and the 69 <structfield>which</structfield> field to 70 <constant>V4L2_SUBDEV_FORMAT_ACTIVE</constant>. They then call the 71 <constant>VIDIOC_SUBDEV_G_CROP</constant> ioctl with a pointer to this 72 structure. The driver fills the members of the <structfield>rect</structfield> 73 field or returns &EINVAL; if the input arguments are invalid, or if cropping 74 is not supported on the given pad.</para> 75 76 <para>To change the current crop rectangle applications set both the 77 <structfield>pad</structfield> and <structfield>which</structfield> fields 78 and all members of the <structfield>rect</structfield> field. They then call 79 the <constant>VIDIOC_SUBDEV_S_CROP</constant> ioctl with a pointer to this 80 structure. The driver verifies the requested crop rectangle, adjusts it 81 based on the hardware capabilities and configures the device. Upon return 82 the &v4l2-subdev-crop; contains the current format as would be returned 83 by a <constant>VIDIOC_SUBDEV_G_CROP</constant> call.</para> 84 85 <para>Applications can query the device capabilities by setting the 86 <structfield>which</structfield> to 87 <constant>V4L2_SUBDEV_FORMAT_TRY</constant>. When set, 'try' crop 88 rectangles are not applied to the device by the driver, but are mangled 89 exactly as active crop rectangles and stored in the sub-device file handle. 90 Two applications querying the same sub-device would thus not interact with 91 each other.</para> 92 93 <para>Drivers must not return an error solely because the requested crop 94 rectangle doesn't match the device capabilities. They must instead modify 95 the rectangle to match what the hardware can provide. The modified format 96 should be as close as possible to the original request.</para> 97 98 <table pgwide="1" frame="none" id="v4l2-subdev-crop"> 99 <title>struct <structname>v4l2_subdev_crop</structname></title> 100 <tgroup cols="3"> 101 &cs-str; 102 <tbody valign="top"> 103 <row> 104 <entry>__u32</entry> 105 <entry><structfield>pad</structfield></entry> 106 <entry>Pad number as reported by the media framework.</entry> 107 </row> 108 <row> 109 <entry>__u32</entry> 110 <entry><structfield>which</structfield></entry> 111 <entry>Crop rectangle to get or set, from 112 &v4l2-subdev-format-whence;.</entry> 113 </row> 114 <row> 115 <entry>&v4l2-rect;</entry> 116 <entry><structfield>rect</structfield></entry> 117 <entry>Crop rectangle boundaries, in pixels.</entry> 118 </row> 119 <row> 120 <entry>__u32</entry> 121 <entry><structfield>reserved</structfield>[8]</entry> 122 <entry>Reserved for future extensions. Applications and drivers must 123 set the array to zero.</entry> 124 </row> 125 </tbody> 126 </tgroup> 127 </table> 128 </refsect1> 129 130 <refsect1> 131 &return-value; 132 133 <variablelist> 134 <varlistentry> 135 <term><errorcode>EBUSY</errorcode></term> 136 <listitem> 137 <para>The crop rectangle can't be changed because the pad is currently 138 busy. This can be caused, for instance, by an active video stream on 139 the pad. The ioctl must not be retried without performing another 140 action to fix the problem first. Only returned by 141 <constant>VIDIOC_SUBDEV_S_CROP</constant></para> 142 </listitem> 143 </varlistentry> 144 <varlistentry> 145 <term><errorcode>EINVAL</errorcode></term> 146 <listitem> 147 <para>The &v4l2-subdev-crop; <structfield>pad</structfield> 148 references a non-existing pad, the <structfield>which</structfield> 149 field references a non-existing format, or cropping is not supported 150 on the given subdev pad.</para> 151 </listitem> 152 </varlistentry> 153 </variablelist> 154 </refsect1> 155 </refentry>
