7.61. ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION¶
VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad
int ioctl(int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp)
int ioctl(int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp)
- File descriptor returned by
- Pointer to struct
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
18.104.22.168. 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.
22.214.171.124. Discovering supported features¶
To discover which targets are supported, the user can perform
VIDIOC_SUBDEV_G_SELECTION on them. Any unsupported target will
Selection targets and flags are documented in Common selection definitions.
||Active or try selection, from enum v4l2_subdev_format_whence.|
||Pad number as reported by the media framework.|
||Target selection rectangle. See Common selection definitions.|
||Flags. See Selection flags.|
||Selection rectangle, in pixels.|
||Reserved for future extensions. Applications and drivers must set the array to zero.|
7.61.5. 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.
- 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
- The struct
padreferences a non-existing pad, the
whichfield references a non-existing format, or the selection target is not supported on the given subdev pad.
VIDIOC_SUBDEV_S_SELECTIONioctl has been called on a read-only subdevice and the
whichfield is set to