add pixelops, improve text

src/drawing/circle.rs

@@ -1,7 +1,6 @@
 //! draw 2d circles
 use crate::Image;
 
-
 impl<T: AsMut<[u8]> + AsRef<[u8]>, const CHANNELS: usize> Image<T, CHANNELS> {
     /// Draws a circle, using the [Bresenham's circle](https://en.wikipedia.org/wiki/Midpoint_circle_algorithm) algorithm.
     /// ```

src/drawing/text.rs

@@ -1,10 +1,13 @@
 //! text raster
 
-use crate::Image;
+use crate::{
+    pixels::{float, Wam},
+    Image,
+};
 use fontdue::{layout::TextStyle, Font};
-use umath::FFloat;
+use umath::{generic_float::Constructors, FF32};
 
-impl<T: AsMut<[u8]> + AsRef<[u8]>> Image<T, 4> {
+impl<const N: usize, T: AsMut<[u8]> + AsRef<[u8]>> Image<T, N> {
     /// Draw text.
     ///
     /// ```
@@ -18,9 +21,9 @@ impl<T: AsMut<[u8]> + AsRef<[u8]>> Image<T, 4> {
     /// ).unwrap();
     /// let mut i: Image<_, 4> = Image::alloc(750, 250).boxed();
     /// i.text(50, 10, 200.0, &font, "hello", [0, 0, 0, 255]);
-    /// # assert_eq!(i.buffer(), include_bytes!("../../tdata/text.imgbuf"));
+    /// # assert_eq!(&**i.buffer(), include_bytes!("../../tdata/text.imgbuf"));
     /// ```
-    pub fn text(&mut self, x: u32, y: u32, size: f32, font: &Font, text: &str, color: [u8; 4]) {
+    pub fn text(&mut self, x: u32, y: u32, size: f32, font: &Font, text: &str, color: [u8; N]) {
         let mut lay =
             fontdue::layout::Layout::new(fontdue::layout::CoordinateSystem::PositiveYDown);
         lay.append(&[font], &TextStyle::new(text, size, 0));
@@ -28,10 +31,6 @@ impl<T: AsMut<[u8]> + AsRef<[u8]>> Image<T, 4> {
             let (metrics, bitmap) = font.rasterize(glpyh.parent, size);
             for i in 0..metrics.width {
                 for j in 0..metrics.height {
-                    // SAFETY: the rasterizer kinda promises that metrics width and height are in bounds
-                    let fg = [color[0], color[1], color[2], unsafe {
-                        *bitmap.get_unchecked(j * metrics.width + i)
-                    }];
                     let x = x + i as u32 + glpyh.x as u32;
                     if x >= self.width() {
                         continue;
@@ -40,49 +39,15 @@ impl<T: AsMut<[u8]> + AsRef<[u8]>> Image<T, 4> {
                     if y >= self.height() {
                         continue;
                     }
+
+                    // SAFETY: the rasterizer kinda promises that metrics width and height are in bounds
+                    let fill = unsafe { float(*bitmap.get_unchecked(j * metrics.width + i)) };
                     // SAFETY: we clampin
-                    let bg = unsafe { self.pixel_mut(x, y) };
-
-                    blend(bg.try_into().unwrap(), fg);
+                    let bg = unsafe { &mut *(self.pixel_mut(x, y).as_mut_ptr() as *mut [u8; N]) };
+                    // SAFETY: fill is 0..=1
+                    *bg = unsafe { bg.wam(color, FF32::one() - fill, fill) };
                 }
             }
         }
     }
 }
-
-pub fn blend(bg: &mut [u8; 4], fg: [u8; 4]) {
-    if fg[3] == 0 {
-        return;
-    }
-    if fg[3] == 255 {
-        *bg = fg;
-        return;
-    }
-    #[allow(clippy::multiple_unsafe_ops_per_block)]
-    // SAFETY: no u8 can possibly become INF / NAN
-    unsafe {
-        let max = FFloat::new(255.0);
-        let bg_a = FFloat::new(bg[3] as f32) / max;
-        let fg_a = FFloat::new(fg[3] as f32) / max;
-        let a = bg_a + fg_a - bg_a * fg_a;
-        if a == 0.0 {
-            return;
-        };
-        // could turn it into array::map
-        *bg = [
-            *(max
-                * ((((FFloat::new(fg[0] as f32) / max) * fg_a)
-                    + ((FFloat::new(bg[0] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
-                    / a)) as u8,
-            *(max
-                * ((((FFloat::new(fg[1] as f32) / max) * fg_a)
-                    + ((FFloat::new(bg[1] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
-                    / a)) as u8,
-            *(max
-                * ((((FFloat::new(fg[2] as f32) / max) * fg_a)
-                    + ((FFloat::new(bg[2] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
-                    / a)) as u8,
-            *(max * a) as u8,
-        ]
-    }
-}

src/lib.rs

@@ -32,6 +32,7 @@ pub mod cloner;
 mod drawing;
 pub(crate) mod math;
 mod overlay;
+pub mod pixels;
 #[cfg(feature = "scale")]
 pub mod scale;
 use cloner::ImageCloner;

src/pixels/blending.rs

@@ -0,0 +1,95 @@
+//! module for pixel blending ops
+use super::{unfloat, Floatify, PMap, Trunc, Unfloatify};
+use umath::FF32;
+
+/// Trait for blending pixels together.
+pub trait Blend<const W: usize> {
+    /// blends self with another pixel
+    fn blend(&mut self, with: [u8; W]);
+}
+
+impl Blend<4> for [u8; 4] {
+    fn blend(&mut self, fg: [u8; 4]) {
+        if fg[3] == 0 {
+            return;
+        }
+        if fg[3] == 255 {
+            *self = fg;
+            return;
+        }
+        let fg = fg.float();
+        let bg = self.float();
+        let a = bg[3] + fg[3] - bg[3] * fg[3];
+        if a == 0.0 {
+            return;
+        };
+        self[..3].copy_from_slice(
+            &fg.trunc()
+                // SAFETY: no u8 can possibly become INF / NAN
+                .pmap(bg.trunc(), |f, b| unsafe {
+                    (f * fg[3] + b * bg[3] * (FF32::new(1.0) - fg[3])) / a
+                })
+                .unfloat(),
+        );
+        self[3] = unfloat(a);
+    }
+}
+
+impl Blend<3> for [u8; 3] {
+    fn blend(&mut self, with: [u8; 3]) {
+        *self = with;
+    }
+}
+
+impl Blend<2> for [u8; 2] {
+    fn blend(&mut self, with: [u8; 2]) {
+        let bg = self.float();
+        let fg = with.float();
+
+        let a = bg[1] + fg[1] - bg[1] * fg[1];
+        if a == 0.0 {
+            return;
+        }
+        *self = [
+            // SAFETY: no u8 can do transform bad
+            (fg[0] * fg[1] + bg[0] * bg[1] * (unsafe { FF32::new(1.0) } - fg[1])) / a,
+            a,
+        ]
+        .unfloat();
+    }
+}
+
+impl Blend<1> for [u8; 1] {
+    fn blend(&mut self, with: [u8; 1]) {
+        *self = with;
+    }
+}
+
+#[cfg(test)]
+mod blend {
+    use super::*;
+
+    macro_rules! blend {
+    ([$($a:literal),+] + [$($b:literal),+] = $what:expr) => {
+        let mut a = [$($a,)+];
+        a.blend([$($b,)+]);
+        assert_eq!(a, $what);
+    };
+}
+
+    #[test]
+    fn test_blend_rgba() {
+        blend!([255, 255, 255, 255] + [255, 255, 255, 255] = [255, 255, 255, 255]);
+        blend!([255, 255, 255, 0] + [255, 255, 255, 255] = [255, 255, 255, 255]);
+        blend!([255, 255, 255, 255] + [255_u8, 255, 255, 0] = [255, 255, 255, 255]);
+        blend!([255, 255, 255, 0] + [255_u8, 255, 255, 0] = [255, 255, 255, 0]);
+    }
+
+    #[test]
+    fn test_blend_ya() {
+        blend!([255, 255] + [255, 255] = [255, 255]);
+        blend!([255, 0] + [255, 255] = [255, 255]);
+        blend!([255, 255] + [255, 0] = [255, 255]);
+        blend!([255, 0] + [255, 0] = [255, 0]);
+    }
+}

src/pixels/mod.rs

@@ -0,0 +1,8 @@
+//! module for pixels ops.
+#![allow(unused_imports)]
+pub mod blending;
+mod utility;
+mod wam;
+pub use blending::Blend;
+pub(crate) use utility::{float, unfloat, Floatify, PMap, Trunc, Unfloatify};
+pub(crate) use wam::Wam;

src/pixels/utility.rs

@@ -0,0 +1,72 @@
+use umath::FF32;
+pub trait Unfloatify<const N: usize> {
+    /// computes 255 * n, for all elements
+    fn unfloat(self) -> [u8; N];
+}
+
+#[inline(always)]
+/// computes 255 * n
+pub fn unfloat(n: FF32) -> u8 {
+    // SAFETY: n is 0..=1
+    unsafe { *(FF32::new(255.0) * n) as u8 }
+}
+
+impl<const N: usize> Unfloatify<N> for [FF32; N] {
+    fn unfloat(self) -> [u8; N] {
+        self.map(unfloat)
+    }
+}
+
+#[rustfmt::skip]
+impl<const N:usize>Unfloatify<N>for[u8; N]{fn unfloat(self)->[u8;N]{self}}
+
+pub trait Floatify<const N: usize> {
+    /// computes n / 255, for all elements
+    fn float(self) -> [FF32; N];
+}
+
+/// computes n / 255
+pub fn float(n: u8) -> FF32 {
+    // SAFETY: 0..=255 / 0..=255 maynt ever be NAN / INF
+    unsafe { FF32::new(n as f32) / FF32::new(255.0) }
+}
+
+impl<const N: usize> Floatify<N> for [u8; N] {
+    fn float(self) -> [FF32; N] {
+        self.map(float)
+    }
+}
+
+#[rustfmt::skip]
+impl<const N:usize>Floatify<N>for[FF32;N]{fn float(self)->[FF32;N]{self}}
+
+pub trait PMap<T, R, const N: usize> {
+    /// think of it like a `a.zip(b).map(f).collect::<[]>()`
+    fn pmap(self, with: Self, f: impl FnMut(T, T) -> R) -> [R; N];
+}
+
+impl<const N: usize, T: Copy, R: Copy> PMap<T, R, N> for [T; N] {
+    fn pmap(self, with: Self, mut f: impl FnMut(T, T) -> R) -> [R; N] {
+        let mut iter = self.into_iter().zip(with).map(|(a, b)| f(a, b));
+        std::array::from_fn(|_| iter.next().unwrap())
+    }
+}
+
+pub trait Trunc<T, const N: usize> {
+    /// it does `a[..a.len() - 1].try_into().unwrap()``.
+    fn trunc(&self) -> [T; N - 1];
+}
+
+impl<const N: usize, T: Copy> Trunc<T, N> for [T; N] {
+    fn trunc(&self) -> [T; N - 1] {
+        self[..N - 1].try_into().unwrap()
+    }
+}
+
+#[test]
+fn trunc() {
+    let x = [1];
+    assert_eq!(x.trunc(), []);
+    let x = [1, 2, 3, 4];
+    assert_eq!(x.trunc(), [1, 2, 3]);
+}

src/pixels/wam.rs

@@ -0,0 +1,37 @@
+use umath::{generic_float::Constructors, FF32};
+
+use super::{float, unfloat, PMap};
+
+pub trait Wam {
+    /// this function weighs the sides and combines
+    ///
+    /// # Safety
+    ///
+    /// pls make l = 0..=f32::MAX/2, r = 0..=f32::MAX/2
+    unsafe fn wam(self, b: Self, l: FF32, r: FF32) -> Self;
+}
+
+impl<const N: usize> Wam for [u8; N] {
+    unsafe fn wam(self, b: Self, l: FF32, r: FF32) -> Self {
+        // SAFETY: read [`weigh`]
+        self.pmap(b, |a, b| unsafe { weigh(a, b, l, r) })
+    }
+}
+
+#[inline(always)]
+/// # Safety
+///
+/// floats must be smart
+unsafe fn weigh(a: u8, b: u8, l: FF32, r: FF32) -> u8 {
+    // SAFETY: float(x) returns 0..=1, 0..=1 * f32::MAX isnt Inf, but if you add 1.0 and then mul by max again, you get inf (big bad, hence unsafe fn)
+    unsafe { unfloat((float(a) * l + float(b) * r).clamp(FF32::zero(), FF32::one())) }
+}
+
+#[test]
+fn weig() {
+    unsafe {
+        assert_eq!(weigh(10, 20, FF32::new(0.5), FF32::new(0.5)), 15);
+        assert_eq!(weigh(10, 20, FF32::new(0.9), FF32::new(0.1)), 11);
+        assert_eq!(weigh(150, 150, FF32::new(1.8), FF32::new(0.8)), 255);
+    }
+}

src/scale/algorithms.rs

@@ -111,32 +111,3 @@ alg!(Hamming);
 /// [Mitchell–Netravali](https://en.wikipedia.org/wiki/Mitchell%E2%80%93Netravali_filters) bicubic filtering.
 pub struct Mitchell {}
 alg!(Mitchell);
-
-impl Nearest {
-    /// Resize a image.
-    /// # Safety
-    ///
-    /// `image` must be as big or bigger than `width`, `height.
-    #[must_use = "function does not modify the original image"]
-    #[deprecated = "use Image::scale instead (note that Image::scale does not support any N. if there is a N you would like to see supported, please open a issue)"]
-    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
-    }
-}