v4l 0.14.0

Safe video4linux (v4l) bindings
Documentation 
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macro_rules! impl_enum_frameintervals {
    () => {
        fn enum_frameintervals(
            &self,
            fourcc: FourCC,
            width: u32,
            height: u32,
        ) -> io::Result<Vec<FrameInterval>> {
            let mut frameintervals = Vec::new();
            let mut v4l2_struct = v4l2_frmivalenum {
                index: 0,
                pixel_format: fourcc.into(),
                width,
                height,
                ..unsafe { mem::zeroed() }
            };

            loop {
                let ret = unsafe {
                    v4l2::ioctl(
                        self.handle().fd(),
                        v4l2::vidioc::VIDIOC_ENUM_FRAMEINTERVALS,
                        &mut v4l2_struct as *mut _ as *mut std::os::raw::c_void,
                    )
                };

                if ret.is_err() {
                    if v4l2_struct.index == 0 {
                        return Err(ret.err().unwrap());
                    } else {
                        return Ok(frameintervals);
                    }
                }

                if let Ok(frame_interval) = FrameInterval::try_from(v4l2_struct) {
                    frameintervals.push(frame_interval);
                }

                v4l2_struct.index += 1;
            }
        }
    };
}

macro_rules! impl_enum_framesizes {
    () => {
        fn enum_framesizes(&self, fourcc: FourCC) -> io::Result<Vec<FrameSize>> {
            let mut framesizes = Vec::new();
            let mut v4l2_struct = v4l2_frmsizeenum {
                index: 0,
                pixel_format: fourcc.into(),
                ..unsafe { mem::zeroed() }
            };

            loop {
                let ret = unsafe {
                    v4l2::ioctl(
                        self.handle().fd(),
                        v4l2::vidioc::VIDIOC_ENUM_FRAMESIZES,
                        &mut v4l2_struct as *mut _ as *mut std::os::raw::c_void,
                    )
                };

                if ret.is_err() {
                    if v4l2_struct.index == 0 {
                        return Err(ret.err().unwrap());
                    } else {
                        return Ok(framesizes);
                    }
                }

                if let Ok(frame_size) = FrameSize::try_from(v4l2_struct) {
                    framesizes.push(frame_size);
                }

                v4l2_struct.index += 1;
            }
        }
    };
}

macro_rules! impl_enum_formats {
    ($typ:expr) => {
        fn enum_formats(&self) -> io::Result<Vec<FormatDescription>> {
            let mut formats: Vec<FormatDescription> = Vec::new();
            let mut v4l2_fmt = v4l2_fmtdesc {
                index: 0,
                type_: $typ as u32,
                ..unsafe { mem::zeroed() }
            };

            let mut ret: io::Result<()>;

            unsafe {
                ret = v4l2::ioctl(
                    self.handle().fd(),
                    v4l2::vidioc::VIDIOC_ENUM_FMT,
                    &mut v4l2_fmt as *mut _ as *mut std::os::raw::c_void,
                );
            }

            if ret.is_err() {
                // Enumerating the first format (at index 0) failed, so there are no formats available
                // for this device. Just return an empty vec in this case.
                return Ok(Vec::new());
            }

            while ret.is_ok() {
                formats.push(FormatDescription::from(v4l2_fmt));
                v4l2_fmt.index += 1;

                unsafe {
                    v4l2_fmt.description = mem::zeroed();
                }

                unsafe {
                    ret = v4l2::ioctl(
                        self.handle().fd(),
                        v4l2::vidioc::VIDIOC_ENUM_FMT,
                        &mut v4l2_fmt as *mut _ as *mut std::os::raw::c_void,
                    );
                }
            }

            Ok(formats)
        }
    };
}

macro_rules! impl_format {
    ($typ:expr) => {
        fn format(&self) -> io::Result<Format> {
            unsafe {
                let mut v4l2_fmt = v4l2_format {
                    type_: $typ as u32,
                    ..mem::zeroed()
                };
                v4l2::ioctl(
                    self.handle().fd(),
                    v4l2::vidioc::VIDIOC_G_FMT,
                    &mut v4l2_fmt as *mut _ as *mut std::os::raw::c_void,
                )?;

                Ok(Format::from(v4l2_fmt.fmt.pix))
            }
        }
    };
}

macro_rules! impl_set_format {
    ($typ:expr) => {
        fn set_format(&self, fmt: &Format) -> io::Result<Format> {
            unsafe {
                let mut v4l2_fmt = v4l2_format {
                    type_: $typ as u32,
                    fmt: v4l2_format__bindgen_ty_1 { pix: (*fmt).into() },
                };
                v4l2::ioctl(
                    self.handle().fd(),
                    v4l2::vidioc::VIDIOC_S_FMT,
                    &mut v4l2_fmt as *mut _ as *mut std::os::raw::c_void,
                )?;
            }

            self.format()
        }
    };
}