1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_SUBDEV_G_SELECTION:
5 **********************************************************
6 ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION
7 **********************************************************
12 VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad
18 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp )
19 :name: VIDIOC_SUBDEV_G_SELECTION
21 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp )
22 :name: VIDIOC_SUBDEV_S_SELECTION
29 File descriptor returned by :ref:`open() <func-open>`.
37 The selections are used to configure various image processing
38 functionality performed by the subdevs which affect the image size. This
39 currently includes cropping, scaling and composition.
41 The selection API replaces
42 :ref:`the old subdev crop API <VIDIOC_SUBDEV_G_CROP>`. All the
43 function of the crop API, and more, are supported by the selections API.
45 See :ref:`subdev` for more information on how each selection target
46 affects the image processing pipeline inside the subdevice.
49 Types of selection targets
50 --------------------------
52 There are two types of selection targets: actual and bounds. The actual
53 targets are the targets which configure the hardware. The BOUNDS target
54 will return a rectangle that contain all possible actual rectangles.
57 Discovering supported features
58 ------------------------------
60 To discover which targets are supported, the user can perform
61 ``VIDIOC_SUBDEV_G_SELECTION`` on them. Any unsupported target will
64 Selection targets and flags are documented in
65 :ref:`v4l2-selections-common`.
68 .. _v4l2-subdev-selection:
70 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
72 .. flat-table:: struct v4l2_subdev_selection
84 - Active or try selection, from enum
85 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
93 - Pad number as reported by the media framework.
101 - Target selection rectangle. See :ref:`v4l2-selections-common`.
109 - Flags. See :ref:`v4l2-selection-flags`.
113 - struct :c:type:`v4l2_rect`
117 - Selection rectangle, in pixels.
125 - Reserved for future extensions. Applications and drivers must set
132 On success 0 is returned, on error -1 and the ``errno`` variable is set
133 appropriately. The generic error codes are described at the
134 :ref:`Generic Error Codes <gen-errors>` chapter.
137 The selection rectangle can't be changed because the pad is
138 currently busy. This can be caused, for instance, by an active video
139 stream on the pad. The ioctl must not be retried without performing
140 another action to fix the problem first. Only returned by
141 ``VIDIOC_SUBDEV_S_SELECTION``
144 The struct :ref:`v4l2_subdev_selection <v4l2-subdev-selection>`
145 ``pad`` references a non-existing pad, the ``which`` field
146 references a non-existing format, or the selection target is not
147 supported on the given subdev pad.