Antti Koskipaa | f6a5cb1 | 2010-06-23 05:03:42 -0300 | [diff] [blame] | 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> |