1// Copyright 2020 the Resvg Authors
2// SPDX-License-Identifier: Apache-2.0 OR MIT
3
4use super::ImageRefMut;
5use rgb::RGBA8;
6use usvg::filter::MorphologyOperator;
7
8/// Applies a morphology filter.
9///
10/// `src` pixels should have a **premultiplied alpha**.
11///
12/// # Allocations
13///
14/// This method will allocate a copy of the `src` image as a back buffer.
15pub fn apply(operator: MorphologyOperator, rx: f32, ry: f32, src: ImageRefMut) {
16 // No point in making matrix larger than image.
17 let columns = std::cmp::min(rx.ceil() as u32 * 2, src.width);
18 let rows = std::cmp::min(ry.ceil() as u32 * 2, src.height);
19 let target_x = (columns as f32 / 2.0).floor() as u32;
20 let target_y = (rows as f32 / 2.0).floor() as u32;
21
22 let width_max = src.width as i32 - 1;
23 let height_max = src.height as i32 - 1;
24
25 let mut buf = vec![RGBA8::default(); src.data.len()];
26 let mut buf = ImageRefMut::new(src.width, src.height, &mut buf);
27 let mut x = 0;
28 let mut y = 0;
29 for _ in src.data.iter() {
30 let mut new_p = RGBA8::default();
31 if operator == MorphologyOperator::Erode {
32 new_p.r = 255;
33 new_p.g = 255;
34 new_p.b = 255;
35 new_p.a = 255;
36 }
37
38 for oy in 0..rows {
39 for ox in 0..columns {
40 let tx = x as i32 - target_x as i32 + ox as i32;
41 let ty = y as i32 - target_y as i32 + oy as i32;
42
43 if tx < 0 || tx > width_max || ty < 0 || ty > height_max {
44 continue;
45 }
46
47 let p = src.pixel_at(tx as u32, ty as u32);
48 if operator == MorphologyOperator::Erode {
49 new_p.r = std::cmp::min(p.r, new_p.r);
50 new_p.g = std::cmp::min(p.g, new_p.g);
51 new_p.b = std::cmp::min(p.b, new_p.b);
52 new_p.a = std::cmp::min(p.a, new_p.a);
53 } else {
54 new_p.r = std::cmp::max(p.r, new_p.r);
55 new_p.g = std::cmp::max(p.g, new_p.g);
56 new_p.b = std::cmp::max(p.b, new_p.b);
57 new_p.a = std::cmp::max(p.a, new_p.a);
58 }
59 }
60 }
61
62 *buf.pixel_at_mut(x, y) = new_p;
63
64 x += 1;
65 if x == src.width {
66 x = 0;
67 y += 1;
68 }
69 }
70
71 // Do not use `mem::swap` because `data` referenced via FFI.
72 src.data.copy_from_slice(buf.data);
73}
74