Raw-rs: Refactor to run multiple steps in a single loop (#1972)

* Prevent extra allocation in convert to RGB step

* Run preprocessing steps in a single loop

* Create new API to call steps in pipeline

* Include transform and gamma correction step

* cargo fmt

* Split scale colors into two steps

* Code relocations

* cargo fmt

* Implement transform traits for all tuples

* Replace Captures trick with the new `use` keyword

libraries/raw-rs/src/processing.rs

@@ -0,0 +1,66 @@
+use crate::CHANNELS_IN_RGB;
+use fortuples::fortuples;
+
+#[derive(Clone, Copy)]
+pub struct RawPixel {
+	pub value: u16,
+	pub row: usize,
+	pub column: usize,
+}
+
+#[derive(Clone, Copy)]
+pub struct Pixel {
+	pub values: [u16; CHANNELS_IN_RGB],
+	pub row: usize,
+	pub column: usize,
+}
+
+pub trait RawPixelTransform {
+	fn apply(&mut self, pixel: RawPixel) -> u16;
+}
+
+impl<T: Fn(RawPixel) -> u16> RawPixelTransform for T {
+	fn apply(&mut self, pixel: RawPixel) -> u16 {
+		self(pixel)
+	}
+}
+
+fortuples! {
+	#[tuples::min_size(1)]
+	#[tuples::max_size(8)]
+	impl RawPixelTransform for #Tuple
+	where
+		#(#Member: RawPixelTransform),*
+	{
+		fn apply(&mut self, mut pixel: RawPixel) -> u16 {
+			#(pixel.value = #self.apply(pixel);)*
+
+			pixel.value
+		}
+	}
+}
+
+pub trait PixelTransform {
+	fn apply(&mut self, pixel: Pixel) -> [u16; CHANNELS_IN_RGB];
+}
+
+impl<T: Fn(Pixel) -> [u16; CHANNELS_IN_RGB]> PixelTransform for T {
+	fn apply(&mut self, pixel: Pixel) -> [u16; CHANNELS_IN_RGB] {
+		self(pixel)
+	}
+}
+
+fortuples! {
+	#[tuples::min_size(1)]
+	#[tuples::max_size(8)]
+	impl PixelTransform for #Tuple
+	where
+		#(#Member: PixelTransform),*
+	{
+		fn apply(&mut self, mut pixel: Pixel) -> [u16; CHANNELS_IN_RGB] {
+			#(pixel.values = #self.apply(pixel);)*
+
+			pixel.values
+		}
+	}
+}