1use crate::{AssetSource, DevicePixels, IsZero, Result, SharedString, Size};
 2use anyhow::anyhow;
 3use resvg::tiny_skia::Pixmap;
 4use std::{hash::Hash, sync::Arc};
 5
 6/// When rendering SVGs, we render them at twice the size to get a higher-quality result.
 7pub const SMOOTH_SVG_SCALE_FACTOR: f32 = 2.;
 8
 9#[derive(Clone, PartialEq, Hash, Eq)]
10pub(crate) struct RenderSvgParams {
11    pub(crate) path: SharedString,
12    pub(crate) size: Size<DevicePixels>,
13}
14
15#[derive(Clone)]
16pub struct SvgRenderer {
17    asset_source: Arc<dyn AssetSource>,
18}
19
20pub enum SvgSize {
21    Size(Size<DevicePixels>),
22    ScaleFactor(f32),
23}
24
25impl SvgRenderer {
26    pub fn new(asset_source: Arc<dyn AssetSource>) -> Self {
27        Self { asset_source }
28    }
29
30    pub(crate) fn render(&self, params: &RenderSvgParams) -> Result<Option<Vec<u8>>> {
31        if params.size.is_zero() {
32            return Err(anyhow!("can't render at a zero size"));
33        }
34
35        // Load the tree.
36        let Some(bytes) = self.asset_source.load(&params.path)? else {
37            return Ok(None);
38        };
39
40        let pixmap = self.render_pixmap(&bytes, SvgSize::Size(params.size))?;
41
42        // Convert the pixmap's pixels into an alpha mask.
43        let alpha_mask = pixmap
44            .pixels()
45            .iter()
46            .map(|p| p.alpha())
47            .collect::<Vec<_>>();
48        Ok(Some(alpha_mask))
49    }
50
51    pub fn render_pixmap(&self, bytes: &[u8], size: SvgSize) -> Result<Pixmap, usvg::Error> {
52        let tree = usvg::Tree::from_data(bytes, &usvg::Options::default())?;
53
54        let size = match size {
55            SvgSize::Size(size) => size,
56            SvgSize::ScaleFactor(scale) => crate::size(
57                DevicePixels((tree.size().width() * scale) as i32),
58                DevicePixels((tree.size().height() * scale) as i32),
59            ),
60        };
61
62        // Render the SVG to a pixmap with the specified width and height.
63        let mut pixmap = resvg::tiny_skia::Pixmap::new(size.width.into(), size.height.into())
64            .ok_or(usvg::Error::InvalidSize)?;
65
66        let scale = size.width.0 as f32 / tree.size().width();
67        let transform = resvg::tiny_skia::Transform::from_scale(scale, scale);
68
69        resvg::render(&tree, transform, &mut pixmap.as_mut());
70
71        Ok(pixmap)
72    }
73}