VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION — Get or set selection rectangles on a subdev pad
int ioctl( | int fd, |
| int request, | |
struct v4l2_subdev_selection *argp); |
fdFile descriptor returned by open().
requestVIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION
argpThis is an experimental interface and may change in the future.
The selections are used to configure various image processing functionality performed by the subdevs which affect the image size. This currently includes cropping, scaling and composition.
The selection API replaces the old subdev crop API. All the function of the crop API, and more, are supported by the selections API.
See the section called “Sub-device Interface” for more information on how each selection target affects the image processing pipeline inside the subdevice.
There are two types of selection targets: actual and bounds. The actual targets are the targets which configure the hardware. The BOUNDS target will return a rectangle that contain all possible actual rectangles.
To discover which targets are supported, the user can
perform VIDIOC_SUBDEV_G_SELECTION on them.
Any unsupported target will return
EINVAL.
Selection targets and flags are documented in the section called “Common selection definitions”.
Table A.109. struct v4l2_subdev_selection
| __u32 | which | Active or try selection, from enum v4l2_subdev_format_whence. |
| __u32 | pad | Pad number as reported by the media framework. |
| __u32 | target | Target selection rectangle. See the section called “Common selection definitions”. |
| __u32 | flags | Flags. See the section called “Selection flags”. |
| struct v4l2_rect | r | Selection rectangle, in pixels. |
| __u32 | reserved[8] | Reserved for future extensions. Applications and drivers must set the array to zero. |
On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.
The selection rectangle can't be changed because the
pad is currently busy. This can be caused, for instance, by
an active video stream on the pad. The ioctl must not be
retried without performing another action to fix the problem
first. Only returned by
VIDIOC_SUBDEV_S_SELECTION
The struct v4l2_subdev_selection
pad references a non-existing
pad, the which field references a
non-existing format, or the selection target is not
supported on the given subdev pad.