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- .. -*- coding: utf-8; mode: rst -*-
- .. _VIDIOC_SUBDEV_G_SELECTION:
- **********************************************************
- ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION
- **********************************************************
- Name
- ====
- VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad
- Synopsis
- ========
- .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp )
- :name: VIDIOC_SUBDEV_G_SELECTION
- .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp )
- :name: VIDIOC_SUBDEV_S_SELECTION
- Arguments
- =========
- ``fd``
- File descriptor returned by :ref:`open() <func-open>`.
- ``argp``
- 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
- :ref:`the old subdev crop API <VIDIOC_SUBDEV_G_CROP>`. All the
- function of the crop API, and more, are supported by the selections API.
- See :ref:`subdev` for more information on how each selection target
- affects the image processing pipeline inside the subdevice.
- 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.
- 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
- :ref:`v4l2-selections-common`.
- .. c:type:: v4l2_subdev_selection
- .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
- .. flat-table:: struct v4l2_subdev_selection
- :header-rows: 0
- :stub-columns: 0
- :widths: 1 1 2
- * - __u32
- - ``which``
- - Active or try selection, from enum
- :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
- * - __u32
- - ``pad``
- - Pad number as reported by the media framework.
- * - __u32
- - ``target``
- - Target selection rectangle. See :ref:`v4l2-selections-common`.
- * - __u32
- - ``flags``
- - Flags. See :ref:`v4l2-selection-flags`.
- * - struct :c:type:`v4l2_rect`
- - ``r``
- - Selection rectangle, 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 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 :c:type:`v4l2_subdev_selection`
- ``pad`` references a non-existing pad, the ``which`` field
- references a non-existing format, or the selection target is not
- supported on the given subdev pad.
|
