From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- Documentation/DocBook/v4l/vidioc-g-crop.xml | 143 ++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 Documentation/DocBook/v4l/vidioc-g-crop.xml (limited to 'Documentation/DocBook/v4l/vidioc-g-crop.xml') diff --git a/Documentation/DocBook/v4l/vidioc-g-crop.xml b/Documentation/DocBook/v4l/vidioc-g-crop.xml new file mode 100644 index 00000000..d235b1de --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-g-crop.xml @@ -0,0 +1,143 @@ + + + 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. + + 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 <structname>v4l2_crop</structname> + + &cs-str; + + + &v4l2-buf-type; + 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, +V4L2_BUF_TYPE_VIDEO_OVERLAY, and custom (driver +defined) types with code V4L2_BUF_TYPE_PRIVATE +and higher. + + + &v4l2-rect; + c + Cropping rectangle. The same co-ordinate system as +for &v4l2-cropcap; bounds is used. + + + +
+ + + + &return-value; + + + + EINVAL + + Cropping is not supported. + + + + + + + -- cgit v1.2.3