bendns' repos / fimg
fast image operations
Diffstat (limited to 'src/pixels/utility.rs')
-rw-r--r--src/pixels/utility.rs72
1 files changed, 72 insertions, 0 deletions
diff --git a/src/pixels/utility.rs b/src/pixels/utility.rs
new file mode 100644
index 0000000..5184f58
--- /dev/null
+++ b/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]);
+}