fast_image_resize/alpha/u8x4/
native.rs

1use crate::alpha::common::{div_and_clip, mul_div_255, RECIP_ALPHA};
2use crate::pixels::U8x4;
3use crate::{ImageView, ImageViewMut};
4
5pub(crate) fn multiply_alpha(
6    src_view: &impl ImageView<Pixel = U8x4>,
7    dst_view: &mut impl ImageViewMut<Pixel = U8x4>,
8) {
9    let src_rows = src_view.iter_rows(0);
10    let dst_rows = dst_view.iter_rows_mut(0);
11    let rows = src_rows.zip(dst_rows);
12
13    for (src_row, dst_row) in rows {
14        for (src_pixel, dst_pixel) in src_row.iter().zip(dst_row.iter_mut()) {
15            *dst_pixel = multiply_alpha_pixel(*src_pixel);
16        }
17    }
18}
19
20pub(crate) fn multiply_alpha_inplace(image_view: &mut impl ImageViewMut<Pixel = U8x4>) {
21    let rows = image_view.iter_rows_mut(0);
22    for row in rows {
23        multiply_alpha_row_inplace(row);
24    }
25}
26
27#[inline(always)]
28pub(crate) fn multiply_alpha_row(src_row: &[U8x4], dst_row: &mut [U8x4]) {
29    for (src_pixel, dst_pixel) in src_row.iter().zip(dst_row) {
30        *dst_pixel = multiply_alpha_pixel(*src_pixel);
31    }
32}
33
34#[inline(always)]
35pub(crate) fn multiply_alpha_row_inplace(row: &mut [U8x4]) {
36    for pixel in row.iter_mut() {
37        *pixel = multiply_alpha_pixel(*pixel);
38    }
39}
40
41#[inline(always)]
42fn multiply_alpha_pixel(mut pixel: U8x4) -> U8x4 {
43    let alpha = pixel.0[3];
44    pixel.0 = [
45        mul_div_255(pixel.0[0], alpha),
46        mul_div_255(pixel.0[1], alpha),
47        mul_div_255(pixel.0[2], alpha),
48        alpha,
49    ];
50    pixel
51}
52
53// Divide
54
55#[inline]
56pub(crate) fn divide_alpha(
57    src_view: &impl ImageView<Pixel = U8x4>,
58    dst_view: &mut impl ImageViewMut<Pixel = U8x4>,
59) {
60    let src_rows = src_view.iter_rows(0);
61    let dst_rows = dst_view.iter_rows_mut(0);
62    let rows = src_rows.zip(dst_rows);
63    for (src_row, dst_row) in rows {
64        divide_alpha_row(src_row, dst_row);
65    }
66}
67
68#[inline]
69pub(crate) fn divide_alpha_inplace(image_view: &mut impl ImageViewMut<Pixel = U8x4>) {
70    let rows = image_view.iter_rows_mut(0);
71    for row in rows {
72        row.iter_mut().for_each(|pixel| {
73            *pixel = divide_alpha_pixel(*pixel);
74        });
75    }
76}
77
78#[inline(always)]
79pub(crate) fn divide_alpha_row(src_row: &[U8x4], dst_row: &mut [U8x4]) {
80    for (src_pixel, dst_pixel) in src_row.iter().zip(dst_row) {
81        *dst_pixel = divide_alpha_pixel(*src_pixel);
82    }
83}
84
85#[inline(always)]
86fn divide_alpha_pixel(mut pixel: U8x4) -> U8x4 {
87    let alpha = pixel.0[3];
88    let recip_alpha = RECIP_ALPHA[alpha as usize];
89    pixel.0 = [
90        div_and_clip(pixel.0[0], recip_alpha),
91        div_and_clip(pixel.0[1], recip_alpha),
92        div_and_clip(pixel.0[2], recip_alpha),
93        alpha,
94    ];
95    pixel
96}
fast_image_resize/alpha/u8x4/native.rs

fast_image_resize/alpha/u8x4/
native.rs
