ioctl VIDIOC_G_CROP, VIDIOC_S_CROP

&manvol;

VIDIOC_G_CROP

VIDIOC_S_CROP

Get or set the current cropping rectangle

    	int ioctl
    	int fd
    	int request
    	struct v4l2_crop *argp

    	int ioctl
    	int fd
    	int request
    	const struct v4l2_crop *argp

## Arguments

`fd`

- &fd;

`request`

- VIDIOC_G_CROP, VIDIOC_S_CROP

`argp`

## Description

To query the cropping rectangle size and position applications set the type field of a v4l2_crop structure to the respective buffer (stream) type and call the `VIDIOC_G_CROP` ioctl with a pointer to this structure. The driver fills the rest of the structure or returns the &EINVAL; if cropping is not supported.

To change the cropping rectangle applications initialize the type and &v4l2-rect; substructure named c of a v4l2_crop structure and call the `VIDIOC_S_CROP` ioctl with a pointer to this structure.

Do not use the multiplanar buffer types. Use `V4L2_BUF_TYPE_VIDEO_CAPTURE` instead of `V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE` and use `V4L2_BUF_TYPE_VIDEO_OUTPUT` instead of `V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`.

The driver first adjusts the requested dimensions against hardware limits, &ie; the bounds given by the capture/output window, and it rounds to the closest possible values of horizontal and vertical offset, width and height. In particular the driver must round the vertical offset of the cropping rectangle to frame lines modulo two, such that the field order cannot be confused.

Second the driver adjusts the image size (the opposite rectangle of the scaling process, source or target depending on the data direction) to the closest size possible while maintaining the current horizontal and vertical scaling factor.

Finally the driver programs the hardware with the actual cropping and image parameters. `VIDIOC_S_CROP` is a write-only ioctl, it does not return the actual parameters. To query them applications must call `VIDIOC_G_CROP` and &VIDIOC-G-FMT;. When the parameters are unsuitable the application may modify the cropping or image parameters and repeat the cycle until satisfactory parameters have been negotiated.

When cropping is not supported then no parameters are changed and `VIDIOC_S_CROP` returns the &EINVAL;.

## struct v4l2_crop

&cs-str;
__u32 | type | Type of the data stream, set by the application. Only these types are valid here: `V4L2_BUF_TYPE_VIDEO_CAPTURE`, `V4L2_BUF_TYPE_VIDEO_OUTPUT` and `V4L2_BUF_TYPE_VIDEO_OVERLAY`. See v4l2-buf-type.
&v4l2-rect; | c | Cropping rectangle. The same co-ordinate system as for &v4l2-cropcap; bounds is used.

&return-value;