+version = "0.4.1"

+exclude = ["src/cat.png", "src/small_cat.png", "benches/"]

+//! `Box<cat>`

+pub mod scale;

+impl<const CHANNELS: usize> Image<Vec<u8>, CHANNELS> {

+ #[cfg(feature = "save")]

+ /// Open a PNG image

+ pub fn open(f: impl AsRef<std::path::Path>) -> Self {

+ let p = std::fs::File::open(f).unwrap();

+ let r = std::io::BufReader::new(p);

+ let dec = png::Decoder::new(r);

+ let mut reader = dec.read_info().unwrap();

+ let mut buf = vec![0; reader.output_buffer_size()];

+ let info = reader.next_frame(&mut buf).unwrap();

+ use png::ColorType::*;

+ match info.color_type {

+ Indexed | Grayscale => {

+ assert_eq!(CHANNELS, 1, "indexed | grayscale requires one channel")

+ }

+ Rgb => assert_eq!(CHANNELS, 3, "rgb requires three channels"),

+ Rgba => assert_eq!(CHANNELS, 4, "rgba requires four channels"),

+ GrayscaleAlpha => assert_eq!(CHANNELS, 2, "ya requires two channels"),

+ }

+ Self::build(info.width, info.height).buf(buf)

+ }

+}

+

+//! holds scaling operations, at current only the Nearest Neighbor

+use crate::Image;

+

+/// [Nearest Neighbor](https://en.wikipedia.org/wiki/Nearest-neighbor_interpolation) image scaling algorithm implementation.

+/// Use [`Nearest::scale`].

+pub struct Nearest;

+impl Nearest {

+ /// Resize a image.

+ /// # Safety

+ ///

+ /// `image` must be as big or bigger than `width`, `height.

+ pub unsafe fn scale<const N: usize>(

+ image: Image<&[u8], N>,

+ width: u32,

+ height: u32,

+ ) -> Image<Vec<u8>, N> {

+ let x_scale = image.width() as f32 / width as f32;

+ let y_scale = image.height() as f32 / height as f32;

+ let mut out = Image::alloc(width, height);

+ for y in 0..height {

+ for x in 0..width {

+ let x1 = ((x as f32 + 0.5) * x_scale).floor() as u32;

+ let y1 = ((y as f32 + 0.5) * y_scale).floor() as u32;

+ // SAFETY: i asked the caller to make sure its ok

+ let px = unsafe { image.pixel(x1, y1) };

+ // SAFETY: were looping over the width and height of out. its ok.

+ unsafe { out.set_pixel(x, y, px) };

+ }

+ }

+ out

+ }

+}

+

+#[test]

+fn test_nearest() {

+ let i = Image::<_, 3>::open("src/cat.png");

+ assert_eq!(

+ unsafe { Nearest::scale(i.as_ref(), 268, 178) }.buffer,

+ Image::<_, 3>::open("src/small_cat.png").buffer

+ );

+}