Function imageproc::drawing::draw_hollow_circle

pub fn draw_hollow_circle<I>(image: &I,
                             center: (i32, i32),
                             radius: i32,
                             color: I::Pixel)
                             -> VecBuffer<I::Pixel> where I: GenericImage, I::Pixel: 'static

Draw as much of a circle as lies inside the image bounds.