fast image operations
| -rw-r--r-- | src/overlay.rs | 39 |
1 files changed, 15 insertions, 24 deletions
diff --git a/src/overlay.rs b/src/overlay.rs index 7f39e49..f57b216 100644 --- a/src/overlay.rs +++ b/src/overlay.rs @@ -406,30 +406,21 @@ impl<T: AsMut<[u8]> + AsRef<[u8]>, U: AsRef<[u8]>> OverlayAt<Image<U, 3>> for Im #[inline] #[cfg_attr(debug_assertions, track_caller)] unsafe fn overlay_at(&mut self, with: &Image<U, 3>, x: u32, y: u32) -> &mut Self { - /// helper macro for defining rgb=>rgb overlays. allows unrolling - macro_rules! o3x3 { - ($n:expr) => {{ - for j in 0..($n as usize) { - let i_x = j * ($n as usize) * 3..(j + 1) * ($n as usize) * 3; - let o_x = ((j + y as usize) * self.width() as usize + x as usize) * 3 - ..((j + y as usize) * self.width() as usize + x as usize + ($n as usize)) - * 3; - // <= because ".." range - debug_assert!(o_x.end <= self.buffer().as_ref().len()); - debug_assert!(i_x.end <= with.buffer().as_ref().len()); - // SAFETY: bounds are ✅ - let a = unsafe { self.buffer.as_mut().get_unchecked_mut(o_x) }; - // SAFETY: we are in ⬜! - let b = unsafe { with.buffer.as_ref().get_unchecked(i_x) }; - a.copy_from_slice(b); - } - }}; - } - // let it unroll - match with.width() { - 8 => o3x3!(8), - 16 => o3x3!(16), // this branch makes 8x8 0.16 times slower; but 16x16 0.2 times faster. - _ => o3x3!(with.width()), + for j in 0..with.height() as usize { + let i_x = // copy entire rows at a time + j * (with.width() as usize) * 3 + ..(j + 1) * (with.width() as usize) * 3; + let o_x = // _ + ((j + y as usize) * self.width() as usize + x as usize) * 3 + ..((j + y as usize) * self.width() as usize + x as usize + with.width() as usize) * 3; + // <= because ".." range + debug_assert!(o_x.end <= self.buffer().as_ref().len()); + debug_assert!(i_x.end <= with.buffer().as_ref().len()); + // SAFETY: bounds are ✅ + let a = unsafe { self.buffer.as_mut().get_unchecked_mut(o_x) }; + // SAFETY: we are in ⬜! + let b = unsafe { with.buffer.as_ref().get_unchecked(i_x) }; + a.copy_from_slice(b); } self } |