mirror of
https://github.com/storytold/lightcraft.git
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242 lines
8.1 KiB
Rust
242 lines
8.1 KiB
Rust
//! Image buffers and basic raster operations for LightCraft.
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//!
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//! - [`Image<T>`]: interleaved, row-major pixels (`Rgb32f = Image<[f32; 3]>`, `Rgba8 = Image<[u8; 4]>`,
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//! `Plane = Image<f32>`).
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//! - Resampling ([`resample`]): separable Lanczos-3 / Mitchell / box, rayon-parallel.
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//! - Blur ([`blur`]): separable Gaussian via repeated box filters (O(1) per pixel in the radius).
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//! - [`Histogram`] of display-encoded RGB + luminance.
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#![forbid(unsafe_code)]
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pub mod blur;
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pub mod histogram;
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pub mod resample;
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pub use histogram::Histogram;
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/// Run `f` over row chunks, in parallel when the `parallel` feature is on.
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pub fn par_rows<T: Send>(data: &mut [T], row_len: usize, f: impl Fn(usize, &mut [T]) + Sync + Send) {
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if row_len == 0 {
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return;
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}
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#[cfg(feature = "parallel")]
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{
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use rayon::prelude::*;
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data.par_chunks_mut(row_len).enumerate().for_each(|(y, row)| f(y, row));
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}
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#[cfg(not(feature = "parallel"))]
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{
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data.chunks_mut(row_len).enumerate().for_each(|(y, row)| f(y, row));
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}
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}
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/// Interleaved row-major image.
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#[derive(Clone, Debug, PartialEq)]
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pub struct Image<T> {
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pub width: usize,
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pub height: usize,
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pub data: Vec<T>,
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}
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pub type Rgb32f = Image<[f32; 3]>;
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pub type Rgba8 = Image<[u8; 4]>;
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pub type Plane = Image<f32>;
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impl<T: Copy + Default> Image<T> {
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pub fn new(width: usize, height: usize) -> Self {
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Self { width, height, data: vec![T::default(); width * height] }
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}
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pub fn filled(width: usize, height: usize, v: T) -> Self {
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Self { width, height, data: vec![v; width * height] }
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}
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pub fn from_fn(width: usize, height: usize, f: impl Fn(usize, usize) -> T) -> Self {
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let mut data = Vec::with_capacity(width * height);
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for y in 0..height {
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for x in 0..width {
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data.push(f(x, y));
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}
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}
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Self { width, height, data }
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}
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#[inline]
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pub fn get(&self, x: usize, y: usize) -> T {
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self.data[y * self.width + x]
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}
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/// Clamped access (edge extension).
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#[inline]
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pub fn get_clamped(&self, x: isize, y: isize) -> T {
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let x = x.clamp(0, self.width as isize - 1) as usize;
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let y = y.clamp(0, self.height as isize - 1) as usize;
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self.data[y * self.width + x]
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}
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#[inline]
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pub fn set(&mut self, x: usize, y: usize, v: T) {
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self.data[y * self.width + x] = v;
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}
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pub fn row(&self, y: usize) -> &[T] {
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&self.data[y * self.width..(y + 1) * self.width]
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}
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pub fn row_mut(&mut self, y: usize) -> &mut [T] {
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&mut self.data[y * self.width..(y + 1) * self.width]
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}
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pub fn len(&self) -> usize {
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self.data.len()
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}
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pub fn is_empty(&self) -> bool {
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self.data.is_empty()
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}
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pub fn map<U: Copy + Default + Send>(&self, f: impl Fn(T) -> U + Sync + Send) -> Image<U>
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where
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T: Sync,
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{
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let mut out = Image::<U>::new(self.width, self.height);
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let w = self.width;
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par_rows(&mut out.data, w, |y, row| {
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let src = &self.data[y * w..(y + 1) * w];
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for (o, s) in row.iter_mut().zip(src) {
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*o = f(*s);
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}
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});
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out
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}
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/// Crop to `[x0, x0+w) × [y0, y0+h)` (clamped to the image).
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pub fn crop(&self, x0: usize, y0: usize, w: usize, h: usize) -> Self {
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let x0 = x0.min(self.width);
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let y0 = y0.min(self.height);
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let w = w.min(self.width - x0);
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let h = h.min(self.height - y0);
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let mut data = Vec::with_capacity(w * h);
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for y in y0..y0 + h {
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data.extend_from_slice(&self.data[y * self.width + x0..y * self.width + x0 + w]);
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}
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Self { width: w, height: h, data }
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}
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/// Rotate 90° clockwise.
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pub fn rotate_cw(&self) -> Self {
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let (w, h) = (self.width, self.height);
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Image::from_fn(h, w, |x, y| self.get(y, h - 1 - x))
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}
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pub fn rotate_180(&self) -> Self {
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let mut d = self.data.clone();
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d.reverse();
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Self { width: self.width, height: self.height, data: d }
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}
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pub fn flip_h(&self) -> Self {
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let mut out = self.clone();
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for y in 0..self.height {
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out.row_mut(y).reverse();
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}
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out
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}
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/// Apply an EXIF orientation (stored → displayed).
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pub fn oriented(&self, o: lightcraft_geom::Orientation) -> Self {
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let (flip, turns) = o.to_parts();
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let mut img = if flip { self.flip_h() } else { self.clone() };
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match turns {
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1 => img = img.rotate_cw(),
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2 => img = img.rotate_180(),
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3 => img = img.rotate_180().rotate_cw(),
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_ => {}
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}
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img
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}
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}
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impl Rgb32f {
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/// Bilinear sample at continuous pixel coordinates (pixel centres at +0.5).
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#[inline]
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pub fn sample_bilinear(&self, x: f32, y: f32) -> [f32; 3] {
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let fx = x - 0.5;
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let fy = y - 0.5;
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let x0 = fx.floor();
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let y0 = fy.floor();
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let tx = fx - x0;
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let ty = fy - y0;
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let (x0, y0) = (x0 as isize, y0 as isize);
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let a = self.get_clamped(x0, y0);
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let b = self.get_clamped(x0 + 1, y0);
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let c = self.get_clamped(x0, y0 + 1);
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let d = self.get_clamped(x0 + 1, y0 + 1);
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std::array::from_fn(|i| {
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let top = a[i] + (b[i] - a[i]) * tx;
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let bot = c[i] + (d[i] - c[i]) * tx;
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top + (bot - top) * ty
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})
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}
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pub fn luminance(&self) -> Plane {
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self.map(lightcraft_color::luminance_2020)
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}
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/// Encode to 8-bit sRGB from linear sRGB values (no gamut conversion).
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pub fn to_srgb8(&self) -> Rgba8 {
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use lightcraft_color::transfer::encode_srgb8;
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self.map(|p| [encode_srgb8(p[0]), encode_srgb8(p[1]), encode_srgb8(p[2]), 255])
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}
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}
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impl Rgba8 {
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/// Raw bytes (RGBA, row-major).
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pub fn as_bytes(&self) -> Vec<u8> {
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self.data.iter().flat_map(|p| *p).collect()
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}
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pub fn from_bytes(width: usize, height: usize, bytes: &[u8]) -> Option<Self> {
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if bytes.len() != width * height * 4 {
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return None;
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}
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Some(Self { width, height, data: bytes.chunks_exact(4).map(|c| [c[0], c[1], c[2], c[3]]).collect() })
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}
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/// Linear Rec.709/sRGB primaries float image from 8-bit sRGB.
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pub fn to_linear(&self) -> Rgb32f {
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use lightcraft_color::transfer::decode_srgb8;
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self.map(|p| [decode_srgb8(p[0]), decode_srgb8(p[1]), decode_srgb8(p[2])])
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use lightcraft_geom::Orientation;
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#[test]
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fn crop_and_rotate() {
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let img = Image::<u32>::from_fn(4, 3, |x, y| (y * 10 + x) as u32);
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let c = img.crop(1, 1, 2, 2);
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assert_eq!(c.data, vec![11, 12, 21, 22]);
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let r = img.rotate_cw();
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assert_eq!((r.width, r.height), (3, 4));
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// top-left of rotated = bottom-left of original
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assert_eq!(r.get(0, 0), 20);
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assert_eq!(r.get(2, 0), 0);
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assert_eq!(img.rotate_cw().rotate_cw().rotate_cw().rotate_cw(), img);
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assert_eq!(img.rotate_cw().rotate_cw(), img.rotate_180());
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}
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#[test]
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fn orientation_matches_geom_mapping() {
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let img = Image::<u32>::from_fn(5, 3, |x, y| (y * 10 + x) as u32);
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for v in 1..=8 {
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let o = Orientation::from_exif(v);
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let out = img.oriented(o);
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for (sx, sy) in [(0usize, 0usize), (4, 0), (2, 1), (0, 2)] {
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let (dx, dy) = o.map(sx as f64 + 0.5, sy as f64 + 0.5, 5.0, 3.0);
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assert_eq!(out.get(dx as usize, dy as usize), img.get(sx, sy), "orientation {v}");
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}
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}
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}
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#[test]
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fn bilinear_at_centres_is_exact() {
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let img = Rgb32f::from_fn(3, 3, |x, y| [x as f32, y as f32, 1.0]);
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assert_eq!(img.sample_bilinear(1.5, 2.5), [1.0, 2.0, 1.0]);
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let m = img.sample_bilinear(1.0, 1.5);
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assert!((m[0] - 0.5).abs() < 1e-6);
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}
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#[test]
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fn srgb8_roundtrip() {
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let img = Rgba8::from_fn(16, 16, |x, y| [(x * 16) as u8, (y * 16) as u8, 7, 255]);
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assert_eq!(img.to_linear().to_srgb8(), img);
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assert_eq!(Rgba8::from_bytes(16, 16, &img.as_bytes()).unwrap(), img);
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}
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}
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