resvg/filter/
morphology.rs

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

resvg/filter/
morphology.rs
