//! Handles image overlay
use super::{assert_unchecked, really_unsafe_index, Image};
use std::simd::SimdInt;
use std::simd::SimdPartialOrd;
use std::simd::{simd_swizzle, Simd};
/// Trait for layering a image ontop of another, with a offset to the second image.
pub trait OverlayAt<W> {
/// Overlay with => self at coordinates x, y, without blending
/// # Safety
///
/// UB if x, y is out of bounds
unsafe fn overlay_at(&mut self, with: &W, x: u32, y: u32) -> &mut Self;
}
/// Trait for layering images ontop of each other.
/// Think `magick a b -layers flatten a`
pub trait Overlay<W> {
/// Overlay with => self (does not blend)
/// # Safety
///
/// UB if a.width != b.width || a.height != b.height
unsafe fn overlay(&mut self, with: &W) -> &mut Self;
}
#[inline]
/// SIMD accelerated rgba => rgb overlay.
///
/// See [blit](https://en.wikipedia.org/wiki/Bit_blit)
unsafe fn blit(rgb: &mut [u8], rgba: &[u8]) {
let mut srci = 0;
let mut dsti = 0;
while dsti + 16 <= rgb.len() {
let old: Simd<u8, 16> = Simd::from_slice(unsafe { rgb.get_unchecked(dsti..dsti + 16) });
let new: Simd<u8, 16> = Simd::from_slice(unsafe { rgba.get_unchecked(srci..srci + 16) });
let threshold = new.simd_ge(Simd::splat(128)).to_int().cast::<u8>();
let mut mask = simd_swizzle!(
threshold,
[3, 3, 3, 7, 7, 7, 11, 11, 11, 15, 15, 15, 0, 0, 0, 0]
);
mask &= Simd::from_array([
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 0, 0, 0, 0,
]);
let new_rgb = simd_swizzle!(new, [0, 1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 14, 0, 0, 0, 0]);
let blended = (new_rgb & mask) | (old & !mask);
blended.copy_to_slice(unsafe { rgb.get_unchecked_mut(dsti..dsti + 16) });
srci += 16;
dsti += 12;
}
while dsti + 3 <= rgb.len() {
if unsafe { *rgba.get_unchecked(srci + 3) } >= 128 {
let src = unsafe { rgba.get_unchecked(srci..srci + 3) };
let end = unsafe { rgb.get_unchecked_mut(dsti..dsti + 3) };
unsafe { std::ptr::copy_nonoverlapping(src.as_ptr(), end.as_mut_ptr(), 3) };
}
srci += 4;
dsti += 3;
}
}
impl Overlay<Image<&[u8], 4>> for Image<&mut [u8], 4> {
#[inline]
unsafe fn overlay(&mut self, with: &Image<&[u8], 4>) -> &mut Self {
debug_assert!(self.width() == with.width());
debug_assert!(self.height() == with.height());
for (i, other_pixels) in with.chunked().enumerate() {
if other_pixels[3] >= 128 {
let idx_begin = unsafe { i.unchecked_mul(4) };
let idx_end = unsafe { idx_begin.unchecked_add(4) };
let own_pixels = unsafe { self.buffer.get_unchecked_mut(idx_begin..idx_end) };
unsafe {
std::ptr::copy_nonoverlapping(
other_pixels.as_ptr(),
own_pixels.as_mut_ptr(),
4,
);
};
}
}
self
}
}
impl OverlayAt<Image<&[u8], 4>> for Image<&mut [u8], 3> {
#[inline]
unsafe fn overlay_at(&mut self, with: &Image<&[u8], 4>, x: u32, y: u32) -> &mut Self {
// SAFETY: caller upholds these
unsafe { assert_unchecked!(x + with.width() <= self.width()) };
unsafe { assert_unchecked!(y + with.height() <= self.height()) };
for j in 0..with.height() {
let i_x = j as usize * with.width() as usize * 4
..(j as usize + 1) * with.width() as usize * 4;
let o_x = ((j as usize + y as usize) * self.width() as usize + x as usize) * 3
..((j as usize + y as usize) * self.width() as usize
+ x as usize
+ with.width() as usize)
* 3;
let rgb = unsafe { self.buffer.get_unchecked_mut(o_x) };
let rgba = unsafe { with.buffer.get_unchecked(i_x) };
unsafe { blit(rgb, rgba) }
}
self
}
}
impl OverlayAt<Image<&[u8], 3>> for Image<&mut [u8], 3> {
/// Overlay a RGB image(with) => self at coordinates x, y.
/// As this is a `RGBxRGB` operation, blending is unnecessary,
/// and this is simply a copy.
///
/// # Safety
///
/// UB if x, y is out of bounds
#[inline]
unsafe fn overlay_at(&mut self, with: &Image<&[u8], 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;
let a = unsafe { self.buffer.get_unchecked_mut(o_x) };
let b = unsafe { with.buffer.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()),
}
self
}
}
impl Overlay<Image<&[u8], 4>> for Image<&mut [u8], 3> {
#[inline]
unsafe fn overlay(&mut self, with: &Image<&[u8], 4>) -> &mut Self {
debug_assert!(self.width() == with.width());
debug_assert!(self.height() == with.height());
for (i, chunk) in with
.buffer
.chunks_exact(with.width() as usize * 4)
.enumerate()
{
let rgb = unsafe {
self.buffer.get_unchecked_mut(
i * with.width() as usize * 3..(i + 1) * with.width() as usize * 3,
)
};
unsafe { blit(rgb, chunk) };
}
self
}
}
impl OverlayAt<Image<&[u8], 4>> for Image<&mut [u8], 4> {
#[inline]
unsafe fn overlay_at(&mut self, with: &Image<&[u8], 4>, x: u32, y: u32) -> &mut Self {
for j in 0..with.height() {
for i in 0..with.width() {
let index = unsafe { really_unsafe_index(i, j, with.width()) };
let their_px = unsafe { with.buffer.get_unchecked(index * 4..index * 4 + 4) };
if unsafe { *their_px.get_unchecked(3) } >= 128 {
let x = unsafe { i.unchecked_add(x) };
let y = unsafe { j.unchecked_add(y) };
let index = unsafe { really_unsafe_index(x, y, self.width()) };
let our_px = unsafe { self.buffer.get_unchecked_mut(index * 4..index * 4 + 4) };
our_px.copy_from_slice(their_px);
}
}
}
self
}
}