119 lines
3.8 KiB
ReStructuredText
119 lines
3.8 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
|
|
|
|
.. _VIDIOC_SUBDEV_G_CROP:
|
|
|
|
************************************************
|
|
ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP
|
|
************************************************
|
|
|
|
Name
|
|
====
|
|
|
|
VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp )
|
|
:name: VIDIOC_SUBDEV_G_CROP
|
|
|
|
.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp )
|
|
:name: VIDIOC_SUBDEV_S_CROP
|
|
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :ref:`open() <func-open>`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`v4l2_subdev_crop`.
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
.. note::
|
|
|
|
This is an :ref:`obsolete` interface and may be removed
|
|
in the future. It is superseded by
|
|
:ref:`the selection API <VIDIOC_SUBDEV_G_SELECTION>`.
|
|
|
|
To retrieve the current crop rectangle applications set the ``pad``
|
|
field of a struct :c:type:`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 :c:type:`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.
|
|
|
|
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.
|
|
|
|
|
|
.. c:type:: v4l2_subdev_crop
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
|
|
|
|
.. flat-table:: struct v4l2_subdev_crop
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - __u32
|
|
- ``pad``
|
|
- Pad number as reported by the media framework.
|
|
* - __u32
|
|
- ``which``
|
|
- Crop rectangle to get or set, from enum
|
|
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
|
|
* - struct :c:type:`v4l2_rect`
|
|
- ``rect``
|
|
- Crop rectangle boundaries, in pixels.
|
|
* - __u32
|
|
- ``reserved``\ [8]
|
|
- Reserved for future extensions. Applications and drivers must set
|
|
the array to zero.
|
|
|
|
|
|
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
|
|
:ref:`Generic Error Codes <gen-errors>` 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 :c:type:`v4l2_subdev_crop` ``pad``
|
|
references a non-existing pad, the ``which`` field references a
|
|
non-existing format, or cropping is not supported on the given
|
|
subdev pad.
|