pride_overlay/effects/
overlay.rs

1use super::Effect;
2use crate::Colour;
3use crate::flags::{FlagData, SvgData, SvgScaleMode};
4use image::GenericImageView;
5use image::{ImageBuffer, Rgba, RgbaImage, imageops::overlay};
6use imageproc::{drawing::draw_filled_rect_mut, rect::Rect};
7use resvg::{
8    tiny_skia::{Pixmap, Transform},
9    usvg::{self, Tree},
10};
11
12/// Effect that overlays a [Flag](crate::flags::Flag) onto an image.
13#[derive(bon::Builder)]
14#[builder(
15    const,
16    builder_type(doc {
17        /// Builder for the [Overlay] effect.
18    })
19)]
20pub struct Overlay {
21    /// Opacity of the overlay, from 0.0 (transparent) to 1.0 (opaque).
22    #[builder(default = Overlay::DEFAULT_OPACITY, with = |percent: f32| percent.clamp(0., 1.))]
23    opacity: f32,
24}
25
26impl Overlay {
27    /// Default opacity for the [Overlay] effect.
28    pub const DEFAULT_OPACITY: f32 = 0.5;
29}
30
31impl Effect for Overlay {
32    fn apply<F>(&self, image: &mut image::DynamicImage, flag: F)
33    where
34        F: FlagData,
35    {
36        if self.opacity == 0. {
37            // no-op for zero opacity
38        } else {
39            let (width, height) = image.dimensions();
40            let flag_overlay = overlay_flag(flag, width, height, self.opacity);
41            overlay(image, &flag_overlay, 0, 0);
42        }
43    }
44}
45
46pub(crate) fn overlay_flag<F: FlagData>(
47    flag: F,
48    width: u32,
49    height: u32,
50    opacity: f32,
51) -> RgbaImage {
52    let alpha = (opacity * u8::MAX as f32) as u8;
53
54    match flag.svg() {
55        Some(svg) => overlay_svg(svg, width, height, alpha),
56        None => overlay_colours(flag.colours(), width, height, alpha),
57    }
58}
59
60fn overlay_svg(svg: &dyn SvgData, width: u32, height: u32, alpha: u8) -> RgbaImage {
61    #[cfg(target_arch = "wasm32")]
62    let tree = Tree::from_data(svg.data(), &usvg::Options::default()).unwrap();
63    #[cfg(not(target_arch = "wasm32"))]
64    let tree = Tree::from_data(svg.data(), &usvg::Options::default()).unwrap();
65    let mut pixmap = Pixmap::new(width, height).unwrap();
66
67    let size = tree.size();
68    let scale_x = width as f32 / size.width();
69    let scale_y = height as f32 / size.height();
70
71    let transform = match svg.scale() {
72        SvgScaleMode::Contain => {
73            let scale = scale_x.min(scale_y);
74            Transform::from_scale(scale, scale).post_translate(
75                (width as f32 - size.width() * scale) / 2.0,
76                (height as f32 - size.height() * scale) / 2.0,
77            )
78        }
79        SvgScaleMode::Cover => {
80            let scale = scale_x.max(scale_y);
81            Transform::from_scale(scale, scale).post_translate(
82                (width as f32 - size.width() * scale) / 2.0,
83                (height as f32 - size.height() * scale) / 2.0,
84            )
85        }
86        SvgScaleMode::Stretch => Transform::from_scale(scale_x, scale_y),
87        SvgScaleMode::None => Transform::identity(),
88    };
89
90    resvg::render(&tree, transform, &mut pixmap.as_mut());
91
92    let mut flag: RgbaImage = ImageBuffer::from_raw(width, height, pixmap.data().to_vec()).unwrap();
93    flag.pixels_mut().for_each(|pixel| pixel[3] = alpha);
94    flag
95}
96
97fn overlay_colours(colours: &[Colour], width: u32, height: u32, alpha: u8) -> RgbaImage {
98    let mut flag_image = RgbaImage::new(width, height);
99    let count = colours.len() as u32;
100
101    for (i, &Colour(r, g, b)) in colours.iter().enumerate() {
102        let i = i as u32;
103        let y_start = (i * height) / count;
104        let y_end = ((i + 1) * height) / count;
105
106        if y_end > y_start {
107            let rect = Rect::at(0, y_start as i32).of_size(width, y_end - y_start);
108            let colour = Rgba([r, g, b, alpha]);
109            draw_filled_rect_mut(&mut flag_image, rect, colour);
110        }
111    }
112
113    flag_image
114}
pride_overlay/effects/overlay.rs

pride_overlay/effects/
overlay.rs
