7.62. ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION¶
7.62.1. Name¶
VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad
7.62.2. Synopsis¶
-
VIDIOC_SUBDEV_G_SELECTION¶
int ioctl(int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp)
-
VIDIOC_SUBDEV_S_SELECTION¶
int ioctl(int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp)
7.62.3. Arguments¶
fd
File descriptor returned by
open()
.argp
Pointer to struct
v4l2_subdev_selection
.
7.62.4. Description¶
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 Sub-device Interface for more information on how each selection target affects the image processing pipeline inside the subdevice.
If the subdev device node has been registered in read-only mode, calls to
VIDIOC_SUBDEV_S_SELECTION
are only valid if the which
field is set to
V4L2_SUBDEV_FORMAT_TRY
, otherwise an error is returned and the errno
variable is set to -EPERM
.
7.62.4.1. Types of selection targets¶
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.
7.62.4.2. Discovering supported features¶
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 Common selection definitions.
-
type v4l2_subdev_selection¶
__u32 |
|
Active or try selection, from enum v4l2_subdev_format_whence. |
__u32 |
|
Pad number as reported by the media framework. |
__u32 |
|
Target selection rectangle. See Common selection definitions. |
__u32 |
|
Flags. See Selection flags. |
struct |
|
Selection rectangle, in pixels. |
__u32 |
|
Stream identifier. |
__u32 |
|
Reserved for future extensions. Applications and drivers must set the array to zero. |
7.62.5. Return Value¶
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.
- EBUSY
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
- EINVAL
The struct
v4l2_subdev_selection
pad
references a non-existing pad, thewhich
field has an unsupported value, or the selection target is not supported on the given subdev pad.- EPERM
The
VIDIOC_SUBDEV_S_SELECTION
ioctl has been called on a read-only subdevice and thewhich
field is set toV4L2_SUBDEV_FORMAT_ACTIVE
.