Refactor allowing multiple pixel formats

src/image.rs

@@ -3,7 +3,7 @@ pub mod farbfeld;
 pub use farbfeld::*;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
-pub struct Pixel {
+pub struct SRGBA {
     pub r: f32,
     pub g: f32,
     pub b: f32,
@@ -12,14 +12,14 @@ pub struct Pixel {
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct Extent {
-    pub x: u32,
-    pub y: u32,
+    pub x: usize,
+    pub y: usize,
 }
 
 #[derive(Debug)]
-pub struct Image {
+pub struct Image<P> {
     pub extent: Extent,
-    pub pixels: Vec<Pixel>,
+    pub pixels: Vec<P>,
 }
 
 #[derive(Debug)]
@@ -28,30 +28,56 @@ pub enum Error {
     Io(std::io::Error),
 }
 
-pub trait Format {
-    fn read<I>(input: &mut I) -> Result<Image, Error>
+pub trait Format<P> {
+    fn read<I>(input: &mut I) -> Result<Image<P>, Error>
     where
         I: std::io::Read;
 
-    fn write<O>(output: &mut O, img: &Image) -> std::io::Result<()>
+    fn write<O>(output: &mut O, img: &Image<P>) -> std::io::Result<()>
     where
         O: std::io::Write;
 }
 
 impl Extent {
-    pub fn size(&self) -> u32 {
+    pub fn size(&self) -> usize {
         self.x * self.y
     }
 }
 
-impl Pixel {
-    pub fn rgba(r: f32, g: f32, b: f32, a: f32) -> Self {
+impl SRGBA {
+    pub fn new(r: f32, g: f32, b: f32, a: f32) -> Self {
         Self { r, g, b, a }
     }
 }
 
-impl std::ops::AddAssign for Pixel {
-    fn add_assign(&mut self, other: Pixel) {
+pub trait Pixel:
+    std::ops::AddAssign
+    + std::ops::MulAssign<f32>
+    + std::ops::DivAssign<f32>
+    + std::ops::Mul<f32, Output = Self>
+    + std::ops::Div<f32, Output = Self>
+    + Clone
+    + Copy
+    + Default
+    + Sized
+{
+}
+
+impl<P> Pixel for P where
+    P: std::ops::AddAssign
+        + std::ops::MulAssign<f32>
+        + std::ops::DivAssign<f32>
+        + std::ops::Mul<f32, Output = Self>
+        + std::ops::Div<f32, Output = Self>
+        + Clone
+        + Copy
+        + Default
+        + Sized
+{
+}
+
+impl std::ops::AddAssign for SRGBA {
+    fn add_assign(&mut self, other: SRGBA) {
         self.r += other.r;
         self.g += other.g;
         self.b += other.b;
@@ -59,7 +85,7 @@ impl std::ops::AddAssign for Pixel {
     }
 }
 
-impl std::ops::MulAssign<f32> for Pixel {
+impl std::ops::MulAssign<f32> for SRGBA {
     fn mul_assign(&mut self, scalar: f32) {
         self.r *= scalar;
         self.g *= scalar;
@@ -68,7 +94,7 @@ impl std::ops::MulAssign<f32> for Pixel {
     }
 }
 
-impl std::ops::DivAssign<f32> for Pixel {
+impl std::ops::DivAssign<f32> for SRGBA {
     fn div_assign(&mut self, scalar: f32) {
         self.r /= scalar;
         self.g /= scalar;
@@ -77,7 +103,7 @@ impl std::ops::DivAssign<f32> for Pixel {
     }
 }
 
-impl std::ops::Mul<f32> for Pixel {
+impl std::ops::Mul<f32> for SRGBA {
     type Output = Self;
 
     fn mul(mut self, scalar: f32) -> Self {
@@ -86,7 +112,7 @@ impl std::ops::Mul<f32> for Pixel {
     }
 }
 
-impl std::ops::Div<f32> for Pixel {
+impl std::ops::Div<f32> for SRGBA {
     type Output = Self;
 
     fn div(mut self, scalar: f32) -> Self {
@@ -95,7 +121,7 @@ impl std::ops::Div<f32> for Pixel {
     }
 }
 
-impl std::default::Default for Pixel {
+impl std::default::Default for SRGBA {
     fn default() -> Self {
         Self {
             r: 0.0,
@@ -112,14 +138,14 @@ impl From<std::io::Error> for Error {
     }
 }
 
-impl Image {
-	pub fn load<F: Format>(path: &str) -> Result<Image, Error> {
-		let file = std::fs::File::open(path)?;
-		F::read(&mut std::io::BufReader::new(file))
-	}
+impl<P> Image<P> {
+    pub fn load<F: Format<P>>(path: &str) -> Result<Image<P>, Error> {
+        let file = std::fs::File::open(path)?;
+        F::read(&mut std::io::BufReader::new(file))
+    }
 
-	pub fn save<F: Format>(&self, path: &str) -> std::io::Result<()> {
-		let file = std::fs::File::create(path)?;
-		F::write(&mut std::io::BufWriter::new(file), self)
-	}
+    pub fn save<F: Format<P>>(&self, path: &str) -> std::io::Result<()> {
+        let file = std::fs::File::create(path)?;
+        F::write(&mut std::io::BufWriter::new(file), self)
+    }
 }

src/image/farbfeld.rs

@@ -2,59 +2,8 @@ use super::*;
 
 pub struct Farbfeld;
 
-fn read_header<I>(input: &mut I) -> Result<Extent, Error>
-where
-    I: std::io::Read,
-{
-    let mut bytes: [u8; 16] = [0; 16];
-    if input.read(&mut bytes)? < 16 || &bytes[0..8] != b"farbfeld" {
-        Err(Error::Invalid)
-    } else {
-        Ok(Extent {
-            x: u32::from_be_bytes(bytes[8..12].try_into().unwrap()),
-            y: u32::from_be_bytes(bytes[12..16].try_into().unwrap()),
-        })
-    }
-}
-
-fn read_pixels<I>(input: &mut I, extent: Extent) -> Result<Vec<Pixel>, Error>
-where
-    I: std::io::Read,
-{
-    let mut pixels = Vec::with_capacity(extent.size() as usize);
-    for _ in 0..extent.size() {
-        pixels.push(read_pixel(input)?);
-    }
-    Ok(pixels)
-}
-
-fn read_pixel<I>(input: &mut I) -> Result<Pixel, Error>
-where
-    I: std::io::Read,
-{
-    let mut bytes: [u8; 8] = [0; 8];
-    if input.read(&mut bytes)? < 8 {
-        Err(Error::Invalid)
-    } else {
-        Ok(Pixel {
-            r: to_channel(bytes[0..2].try_into().unwrap()),
-            g: to_channel(bytes[2..4].try_into().unwrap()),
-            b: to_channel(bytes[4..6].try_into().unwrap()),
-            a: to_channel(bytes[6..8].try_into().unwrap()),
-        })
-    }
-}
-
-fn to_channel(bytes: [u8; 2]) -> f32 {
-    u16::from_be_bytes(bytes) as f32 / u16::MAX as f32
-}
-
-fn from_channel(channel: f32) -> [u8; 2] {
-    ((channel * u16::MAX as f32) as u16).to_be_bytes()
-}
-
-impl Format for Farbfeld {
-    fn read<I>(input: &mut I) -> Result<Image, Error>
+impl Format<SRGBA> for Farbfeld {
+    fn read<I>(input: &mut I) -> Result<Image<SRGBA>, Error>
     where
         I: std::io::Read,
     {
@@ -65,13 +14,13 @@ impl Format for Farbfeld {
         })
     }
 
-    fn write<O>(output: &mut O, img: &Image) -> std::io::Result<()>
+    fn write<O>(output: &mut O, img: &Image<SRGBA>) -> std::io::Result<()>
     where
         O: std::io::Write,
     {
         output.write_all(b"farbfeld")?;
-        output.write_all(&img.extent.x.to_be_bytes())?;
-        output.write_all(&img.extent.y.to_be_bytes())?;
+        output.write_all(&(img.extent.x as u32).to_be_bytes())?;
+        output.write_all(&(img.extent.y as u32).to_be_bytes())?;
         for pixel in &img.pixels {
             output.write_all(&from_channel(pixel.r))?;
             output.write_all(&from_channel(pixel.g))?;
@@ -82,6 +31,62 @@ impl Format for Farbfeld {
     }
 }
 
+fn read_header<I>(input: &mut I) -> Result<Extent, Error>
+where
+    I: std::io::Read,
+{
+    let mut bytes: [u8; 16] = [0; 16];
+    if input.read(&mut bytes)? < 16 || &bytes[0..8] != b"farbfeld" {
+        Err(Error::Invalid)
+    } else {
+        Ok(Extent {
+            x: be_u32_at(&bytes, 8) as usize,
+            y: be_u32_at(&bytes, 12) as usize,
+        })
+    }
+}
+
+fn read_pixels<I>(input: &mut I, extent: Extent) -> Result<Vec<SRGBA>, Error>
+where
+    I: std::io::Read,
+{
+    let mut pixels = Vec::with_capacity(extent.size() as usize);
+    for _ in 0..extent.size() {
+        pixels.push(read_pixel(input)?);
+    }
+    Ok(pixels)
+}
+
+fn read_pixel<I>(input: &mut I) -> Result<SRGBA, Error>
+where
+    I: std::io::Read,
+{
+    let mut bytes: [u8; 8] = [0; 8];
+    if input.read(&mut bytes)? < 8 {
+        Err(Error::Invalid)
+    } else {
+        Ok(SRGBA {
+            r: to_channel(bytes[0..2].try_into().unwrap()),
+            g: to_channel(bytes[2..4].try_into().unwrap()),
+            b: to_channel(bytes[4..6].try_into().unwrap()),
+            a: to_channel(bytes[6..8].try_into().unwrap()),
+        })
+    }
+}
+
+fn be_u32_at(bytes: &[u8], start: usize) -> u32 {
+    let end = start + std::mem::size_of::<u32>();
+    u32::from_be_bytes(bytes[start..end].try_into().unwrap())
+}
+
+fn to_channel(bytes: [u8; 2]) -> f32 {
+    u16::from_be_bytes(bytes) as f32 / u16::MAX as f32
+}
+
+fn from_channel(channel: f32) -> [u8; 2] {
+    ((channel * u16::MAX as f32) as u16).to_be_bytes()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -177,7 +182,7 @@ mod tests {
     fn write_magic() {
         let img = Image {
             extent: Extent { x: 1, y: 1 },
-            pixels: vec![Pixel {
+            pixels: vec![SRGBA {
                 r: 0.0,
                 g: 0.0,
                 b: 0.0,
@@ -193,7 +198,7 @@ mod tests {
     fn write_extent() {
         let img = Image {
             extent: Extent { x: 1, y: 2 },
-            pixels: vec![Pixel {
+            pixels: vec![SRGBA {
                 r: 0.0,
                 g: 0.0,
                 b: 0.0,
@@ -210,7 +215,7 @@ mod tests {
     fn write_pixel() {
         let img = Image {
             extent: Extent { x: 1, y: 1 },
-            pixels: vec![Pixel {
+            pixels: vec![SRGBA {
                 r: 0.0,
                 g: 0.25,
                 b: 0.5,

src/kernel.rs

@@ -1,7 +1,9 @@
 use crate::*;
 
 pub trait Kernel {
-    fn convolve(&self, img: &image::Image) -> image::Image;
+    fn convolve<P>(&self, img: &image::Image<P>) -> image::Image<P>
+    where
+        P: image::Pixel;
 }
 
 fn sum<const N: usize>(kernel: &[[f32; N]; N]) -> f32 {
@@ -15,9 +17,12 @@ fn sum<const N: usize>(kernel: &[[f32; N]; N]) -> f32 {
 }
 
 impl<const N: usize> Kernel for [[f32; N]; N] {
-    fn convolve(&self, img: &image::Image) -> image::Image {
-        let l = N as u32 / 2;
-		let mag = sum(self);
+    fn convolve<P>(&self, img: &image::Image<P>) -> image::Image<P>
+    where
+        P: image::Pixel,
+    {
+        let l = N / 2;
+        let mag = sum(self);
 
         let extent = image::Extent {
             x: img.extent.x - 2 * l,
@@ -26,8 +31,8 @@ impl<const N: usize> Kernel for [[f32; N]; N] {
 
         let mut pixels = Vec::with_capacity(extent.size() as usize);
         for y in 0..extent.y {
-			for x in 0..extent.x {
-                let mut pixel = image::Pixel::default();
+            for x in 0..extent.x {
+                let mut pixel = P::default();
                 for i in 0..N {
                     for j in 0..N {
                         let img_x = x as usize + i;
@@ -52,7 +57,7 @@ mod tests {
     fn size_of_result_img() {
         let input = image::Image {
             extent: image::Extent { x: 6, y: 10 },
-            pixels: vec![image::Pixel::default(); 60],
+            pixels: vec![0.0; 60],
         };
         let kernel = [[1.0, 1.0, 1.0], [1.0, 1.0, 1.0], [1.0, 1.0, 1.0]];
         let output = kernel.convolve(&input);
@@ -65,15 +70,15 @@ mod tests {
         let input = image::Image {
             extent: image::Extent { x: 3, y: 3 },
             pixels: vec![
-                image::Pixel::rgba(0.1, 0.0, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.2, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.0, 0.3, 1.0),
-                image::Pixel::rgba(0.2, 0.0, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.3, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.0, 0.1, 1.0),
-                image::Pixel::rgba(0.3, 0.0, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.1, 0.0, 1.0),
-                image::Pixel::rgba(0.0, 0.0, 0.2, 1.0),
+                image::SRGBA::new(0.1, 0.0, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.2, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.0, 0.3, 1.0),
+                image::SRGBA::new(0.2, 0.0, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.3, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.0, 0.1, 1.0),
+                image::SRGBA::new(0.3, 0.0, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.1, 0.0, 1.0),
+                image::SRGBA::new(0.0, 0.0, 0.2, 1.0),
             ],
         };
         let kernel = [[0.1, 0.2, 0.3], [0.4, 0.5, 0.6], [0.7, 0.8, 0.9]];