7.59. ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP¶
7.59.1. Name¶
VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad
7.59.2. Synopsis¶
-
VIDIOC_SUBDEV_G_CROP¶
int ioctl(int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp)
-
VIDIOC_SUBDEV_S_CROP¶
int ioctl(int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp)
7.59.3. Arguments¶
fd
File descriptor returned by
open()
.argp
Pointer to struct
v4l2_subdev_crop
.
7.59.4. Description¶
Note
This is an Obsolete API Elements interface and may be removed in the future. It is
superseded by the selection API. No new
extensions to the v4l2_subdev_crop
structure will be accepted.
To retrieve the current crop rectangle applications set the pad
field of a struct v4l2_subdev_crop
to the
desired pad number as reported by the media API and the which
field
to V4L2_SUBDEV_FORMAT_ACTIVE
. They then call the
VIDIOC_SUBDEV_G_CROP
ioctl with a pointer to this structure. The
driver fills the members of the rect
field or returns EINVAL
error
code if the input arguments are invalid, or if cropping is not supported
on the given pad.
To change the current crop rectangle applications set both the pad
and which
fields and all members of the rect
field. They then
call the VIDIOC_SUBDEV_S_CROP
ioctl with a pointer to this
structure. The driver verifies the requested crop rectangle, adjusts it
based on the hardware capabilities and configures the device. Upon
return the struct v4l2_subdev_crop
contains the current format as would be returned by a
VIDIOC_SUBDEV_G_CROP
call.
Applications can query the device capabilities by setting the which
to V4L2_SUBDEV_FORMAT_TRY
. When set, ‘try’ crop rectangles are not
applied to the device by the driver, but are mangled exactly as active
crop rectangles and stored in the sub-device file handle. Two
applications querying the same sub-device would thus not interact with
each other.
If the subdev device node has been registered in read-only mode, calls to
VIDIOC_SUBDEV_S_CROP
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
.
Drivers must not return an error solely because the requested crop rectangle doesn’t match the device capabilities. They must instead modify the rectangle to match what the hardware can provide. The modified format should be as close as possible to the original request.
-
type v4l2_subdev_crop¶
__u32 |
|
Pad number as reported by the media framework. |
__u32 |
|
Crop rectangle to get or set, from enum v4l2_subdev_format_whence. |
struct |
|
Crop rectangle boundaries, in pixels. |
__u32 |
|
Stream identifier. |
__u32 |
|
Reserved for future extensions. Applications and drivers must set the array to zero. |
7.59.5. 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 crop 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_CROP
- EINVAL
The struct
v4l2_subdev_crop
pad
references a non-existing pad, thewhich
field has an unsupported value, or cropping is not supported on the given subdev pad.- EPERM
The
VIDIOC_SUBDEV_S_CROP
ioctl has been called on a read-only subdevice and thewhich
field is set toV4L2_SUBDEV_FORMAT_ACTIVE
.