1 .. SPDX-License-Identifier: GFDL-1.1-no-invari 1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L 2 .. c:namespace:: V4L
3 3
4 .. _VIDIOC_G_CROP: 4 .. _VIDIOC_G_CROP:
5 5
6 ********************************** 6 **********************************
7 ioctl VIDIOC_G_CROP, VIDIOC_S_CROP 7 ioctl VIDIOC_G_CROP, VIDIOC_S_CROP
8 ********************************** 8 **********************************
9 9
10 Name 10 Name
11 ==== 11 ====
12 12
13 VIDIOC_G_CROP - VIDIOC_S_CROP - Get or set the 13 VIDIOC_G_CROP - VIDIOC_S_CROP - Get or set the current cropping rectangle
14 14
15 Synopsis 15 Synopsis
16 ======== 16 ========
17 17
18 .. c:macro:: VIDIOC_G_CROP 18 .. c:macro:: VIDIOC_G_CROP
19 19
20 ``int ioctl(int fd, VIDIOC_G_CROP, struct v4l2 20 ``int ioctl(int fd, VIDIOC_G_CROP, struct v4l2_crop *argp)``
21 21
22 .. c:macro:: VIDIOC_S_CROP 22 .. c:macro:: VIDIOC_S_CROP
23 23
24 ``int ioctl(int fd, VIDIOC_S_CROP, const struc 24 ``int ioctl(int fd, VIDIOC_S_CROP, const struct v4l2_crop *argp)``
25 25
26 Arguments 26 Arguments
27 ========= 27 =========
28 28
29 ``fd`` 29 ``fd``
30 File descriptor returned by :c:func:`open( 30 File descriptor returned by :c:func:`open()`.
31 31
32 ``argp`` 32 ``argp``
33 Pointer to struct :c:type:`v4l2_crop`. 33 Pointer to struct :c:type:`v4l2_crop`.
34 34
35 Description 35 Description
36 =========== 36 ===========
37 37
38 To query the cropping rectangle size and posit 38 To query the cropping rectangle size and position applications set the
39 ``type`` field of a struct :c:type:`v4l2_crop` 39 ``type`` field of a struct :c:type:`v4l2_crop` structure to the
40 respective buffer (stream) type and call the : 40 respective buffer (stream) type and call the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` ioctl
41 with a pointer to this structure. The driver f 41 with a pointer to this structure. The driver fills the rest of the
42 structure or returns the ``EINVAL`` error code 42 structure or returns the ``EINVAL`` error code if cropping is not supported.
43 43
44 To change the cropping rectangle applications 44 To change the cropping rectangle applications initialize the ``type``
45 and struct :c:type:`v4l2_rect` substructure na 45 and struct :c:type:`v4l2_rect` substructure named ``c`` of a
46 v4l2_crop structure and call the :ref:`VIDIOC_ 46 v4l2_crop structure and call the :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctl with a pointer
47 to this structure. 47 to this structure.
48 48
49 The driver first adjusts the requested dimensi 49 The driver first adjusts the requested dimensions against hardware
50 limits, i. e. the bounds given by the capture/ 50 limits, i. e. the bounds given by the capture/output window, and it
51 rounds to the closest possible values of horiz 51 rounds to the closest possible values of horizontal and vertical offset,
52 width and height. In particular the driver mus 52 width and height. In particular the driver must round the vertical
53 offset of the cropping rectangle to frame line 53 offset of the cropping rectangle to frame lines modulo two, such that
54 the field order cannot be confused. 54 the field order cannot be confused.
55 55
56 Second the driver adjusts the image size (the 56 Second the driver adjusts the image size (the opposite rectangle of the
57 scaling process, source or target depending on 57 scaling process, source or target depending on the data direction) to
58 the closest size possible while maintaining th 58 the closest size possible while maintaining the current horizontal and
59 vertical scaling factor. 59 vertical scaling factor.
60 60
61 Finally the driver programs the hardware with 61 Finally the driver programs the hardware with the actual cropping and
62 image parameters. :ref:`VIDIOC_S_CROP <VIDIOC_ 62 image parameters. :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` is a write-only ioctl, it does not
63 return the actual parameters. To query them ap 63 return the actual parameters. To query them applications must call
64 :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref: 64 :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_G_FMT`. When the
65 parameters are unsuitable the application may 65 parameters are unsuitable the application may modify the cropping or
66 image parameters and repeat the cycle until sa 66 image parameters and repeat the cycle until satisfactory parameters have
67 been negotiated. 67 been negotiated.
68 68
69 When cropping is not supported then no paramet 69 When cropping is not supported then no parameters are changed and
70 :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` returns t 70 :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` returns the ``EINVAL`` error code.
71 71
72 .. c:type:: v4l2_crop 72 .. c:type:: v4l2_crop
73 73
74 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm 74 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
75 75
76 .. flat-table:: struct v4l2_crop 76 .. flat-table:: struct v4l2_crop
77 :header-rows: 0 77 :header-rows: 0
78 :stub-columns: 0 78 :stub-columns: 0
79 :widths: 1 1 2 79 :widths: 1 1 2
80 80
81 * - __u32 81 * - __u32
82 - ``type`` 82 - ``type``
83 - Type of the data stream, set by the ap 83 - Type of the data stream, set by the application. Only these types
84 are valid here: ``V4L2_BUF_TYPE_VIDEO_ 84 are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``, ``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``,
85 ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, ``V4L2 85 ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`` and
86 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See : 86 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :c:type:`v4l2_buf_type` and the note below.
87 * - struct :c:type:`v4l2_rect` 87 * - struct :c:type:`v4l2_rect`
88 - ``c`` 88 - ``c``
89 - Cropping rectangle. The same co-ordina 89 - Cropping rectangle. The same co-ordinate system as for struct
90 :c:type:`v4l2_cropcap` ``bounds`` is u 90 :c:type:`v4l2_cropcap` ``bounds`` is used.
91 91
92 .. note:: 92 .. note::
93 Unfortunately in the case of multiplanar bu 93 Unfortunately in the case of multiplanar buffer types
94 (``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and 94 (``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE``)
95 this API was messed up with regards to how 95 this API was messed up with regards to how the :c:type:`v4l2_crop` ``type`` field
96 should be filled in. Some drivers only acce 96 should be filled in. Some drivers only accepted the ``_MPLANE`` buffer type while
97 other drivers only accepted a non-multiplan 97 other drivers only accepted a non-multiplanar buffer type (i.e. without the
98 ``_MPLANE`` at the end). 98 ``_MPLANE`` at the end).
99 99
100 Starting with kernel 4.13 both variations a 100 Starting with kernel 4.13 both variations are allowed.
101 101
102 Return Value 102 Return Value
103 ============ 103 ============
104 104
105 On success 0 is returned, on error -1 and the 105 On success 0 is returned, on error -1 and the ``errno`` variable is set
106 appropriately. The generic error codes are des 106 appropriately. The generic error codes are described at the
107 :ref:`Generic Error Codes <gen-errors>` chapte 107 :ref:`Generic Error Codes <gen-errors>` chapter.
108 108
109 ENODATA 109 ENODATA
110 Cropping is not supported for this input o 110 Cropping is not supported for this input or output.
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