packing trait

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fimg"
-version = "0.4.25"
+version = "0.4.26"
 authors = ["bend-n <bend.n@outlook.com>"]
 license = "MIT"
 edition = "2021"

src/blur.rs

@@ -1,6 +1,6 @@
 use stackblur_iter::imgref::ImgRefMut;
 
-use crate::{pixels::convert::PFrom, Image};
+use crate::Image;
 
 impl<T: AsMut<[u32]> + AsRef<[u32]>> Image<T, 1> {
     /// Blur a image of packed 32 bit integers, `[0xAARRGGBB]`.
@@ -13,8 +13,7 @@ impl<T: AsMut<[u32]> + AsRef<[u32]>> Image<T, 1> {
 
 impl<const N: usize> Image<Box<[u8]>, N>
 where
-    [u8; 4]: PFrom<N>,
-    [u8; N]: PFrom<4>,
+    [u8; N]: crate::Pack,
 {
     /// Blur a image.
     /// ```
@@ -38,8 +37,7 @@ where
 
 impl<const N: usize> Image<&[u8], N>
 where
-    [u8; 4]: PFrom<N>,
-    [u8; N]: PFrom<4>,
+    [u8; N]: crate::Pack,
 {
     /// Blur a image.
     pub fn blur(self, radius: usize) -> Image<Box<[u8]>, N> {

src/convert.rs

@@ -1,6 +1,6 @@
 //! define From's for images.
 //! these conversions are defined by [`PFrom`].
-use crate::{pixels::convert::PFrom, Image};
+use crate::{pixels::convert::PFrom, Image, Pack};
 
 fn map<const A: usize, const B: usize>(image: Image<&[u8], A>) -> Image<Box<[u8]>, B>
 where
@@ -64,33 +64,13 @@ boxconv!(4 => 1);
 boxconv!(4 => 2);
 boxconv!(4 => 3);
 
-#[inline]
-pub const fn pack([r, g, b, a]: [u8; 4]) -> u32 {
-    ((a as u32) << 24) | ((r as u32) << 16) | ((g as u32) << 8) | (b as u32)
-}
-
-#[inline]
-pub const fn unpack(n: u32) -> [u8; 4] {
-    [
-        ((n >> 16) & 0xFF) as u8,
-        ((n >> 8) & 0xFF) as u8,
-        (n & 0xFF) as u8,
-        ((n >> 24) & 0xFF) as u8,
-    ]
-}
-
 impl<const N: usize> From<Image<&[u8], N>> for Image<Box<[u32]>, 1>
 where
-    [u8; 4]: PFrom<N>,
+    [u8; N]: Pack,
 {
     /// Pack into ARGB.
     fn from(value: Image<&[u8], N>) -> Self {
-        let buf = value
-            .chunked()
-            .copied()
-            .map(PFrom::pfrom)
-            .map(pack)
-            .collect();
+        let buf = value.chunked().map(Pack::pack).collect();
         // SAFETY: ctor
         unsafe { Self::new(value.width, value.height, buf) }
     }
@@ -98,18 +78,14 @@ where
 
 pub fn unpack_all<const N: usize>(buffer: &[u32]) -> impl Iterator<Item = u8> + '_
 where
-    [u8; N]: PFrom<4>,
+    [u8; N]: Pack,
 {
-    buffer
-        .iter()
-        .copied()
-        .map(unpack)
-        .flat_map(<[u8; N] as PFrom<4>>::pfrom)
+    buffer.iter().copied().flat_map(<[u8; N]>::unpack)
 }
 
 impl<const N: usize> From<Image<&[u32], 1>> for Image<Box<[u8]>, N>
 where
-    [u8; N]: PFrom<4>,
+    [u8; N]: Pack,
 {
     fn from(value: Image<&[u32], 1>) -> Self {
         let buf = unpack_all(value.buffer).collect();

src/drawing/text.rs

@@ -1,9 +1,8 @@
 //! text raster
 
 use crate::{
-    convert::{pack, unpack},
     pixels::{float, Wam},
-    Image,
+    Image, Pack,
 };
 use fontdue::{layout::TextStyle, Font};
 use umath::{generic_float::Constructors, FF32};
@@ -37,11 +36,12 @@ impl Image<&mut [u32], 1> {
                     // 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 { unpack(*self.buffer.get_unchecked(self.at(x, y))) };
+                    let bg: [u8; 4] =
+                        unsafe { Pack::unpack(*self.buffer.get_unchecked(self.at(x, y))) };
                     // SAFETY: see above
                     *unsafe { self.buffer.get_unchecked_mut(self.at(x, y)) } =
                         // SAFETY: fill is 0..=1
-                        pack(unsafe { bg.wam(color, FF32::one() - fill, fill) });
+                        Pack::pack(unsafe { &bg.wam(color, FF32::one() - fill, fill) });
                 }
             }
         }

src/lib.rs

@@ -84,6 +84,8 @@ mod drawing;
 mod r#dyn;
 pub(crate) mod math;
 mod overlay;
+mod pack;
+pub use pack::Pack;
 pub mod pixels;
 #[cfg(feature = "scale")]
 pub mod scale;

src/pack.rs

@@ -0,0 +1,55 @@
+//! trait for packing pixels
+
+use crate::pixels::convert::{PFrom, RGB, RGBA, Y, YA};
+
+#[inline]
+pub const fn pack([r, g, b, a]: [u8; 4]) -> u32 {
+    ((a as u32) << 24) | ((r as u32) << 16) | ((g as u32) << 8) | (b as u32)
+}
+
+#[inline]
+pub const fn unpack(n: u32) -> [u8; 4] {
+    [
+        ((n >> 16) & 0xFF) as u8,
+        ((n >> 8) & 0xFF) as u8,
+        (n & 0xFF) as u8,
+        ((n >> 24) & 0xFF) as u8,
+    ]
+}
+
+/// packs and unpacks this pixel
+/// note that `unpack(pack(p))` may not equal `p`
+pub trait Pack<P = u32> {
+    /// pack this pixel
+    fn pack(&self) -> P;
+    /// unpacks this pixel
+    fn unpack(from: P) -> Self;
+}
+
+macro_rules! simple {
+    ($p:ident) => {
+        impl Pack for $p {
+            fn pack(&self) -> u32 {
+                pack(PFrom::pfrom(*self))
+            }
+
+            fn unpack(from: u32) -> $p {
+                PFrom::pfrom(unpack(from))
+            }
+        }
+    };
+}
+simple!(RGBA);
+simple!(RGB);
+simple!(YA);
+simple!(Y);
+
+impl Pack<u8> for Y {
+    fn pack(&self) -> u8 {
+        self[0]
+    }
+
+    fn unpack(from: u8) -> Self {
+        [from]
+    }
+}

src/show.rs

@@ -2,12 +2,12 @@ use crate::Image;
 
 #[cfg(feature = "real-show")]
 mod real {
-    use crate::{pixels::convert::PFrom, Image};
+    use crate::Image;
     use minifb::{Key, Window};
 
     pub fn show<const CHANNELS: usize>(i: Image<&[u8], CHANNELS>)
     where
-        [u8; 4]: PFrom<CHANNELS>,
+        [u8; CHANNELS]: crate::Pack,
     {
         let mut win = Window::new(
             "show",