| 1 | //! SVG and SVGZ through resvg. The parsed tree is kept so the image can be re-rasterised at |
| 2 | //! the current zoom and stay sharp. |
| 3 | |
| 4 | use std::path::Path; |
| 5 | use std::sync::{Arc, LazyLock}; |
| 6 | |
| 7 | use resvg::{tiny_skia, usvg}; |
| 8 | |
| 9 | use super::{DecodedImage, Options, Refine}; |
| 10 | |
| 11 | /// Longest side of any raster; zooming further shows this one magnified. |
| 12 | pub const MAX_RASTER: u32 = 8192; |
| 13 | |
| 14 | /// System fonts for `<text>`, loaded once on first use. |
| 15 | static FONTS: LazyLock<Arc<usvg::fontdb::Database>> = LazyLock::new(|| { |
| 16 | let mut db = usvg::fontdb::Database::new(); |
| 17 | db.load_system_fonts(); |
| 18 | Arc::new(db) |
| 19 | }); |
| 20 | |
| 21 | pub struct Svg { |
| 22 | tree: usvg::Tree, |
| 23 | /// Intrinsic size, rounded up to whole pixels. |
| 24 | size: [u32; 2], |
| 25 | } |
| 26 | |
| 27 | pub fn decode(path: &Path, opts: &Options) -> anyhow::Result<DecodedImage> { |
| 28 | let data = std::fs::read(path)?; |
| 29 | let options = usvg::Options { |
| 30 | resources_dir: path.parent().map(Path::to_path_buf), |
| 31 | fontdb: FONTS.clone(), |
| 32 | ..Default::default() |
| 33 | }; |
| 34 | let tree = usvg::Tree::from_data(&data, &options)?; |
| 35 | let s = tree.size(); |
| 36 | let size = [ |
| 37 | (s.width().ceil() as u32).max(1), |
| 38 | (s.height().ceil() as u32).max(1), |
| 39 | ]; |
| 40 | let svg = Arc::new(Svg { tree, size }); |
| 41 | // Never more pixels than the window needs to start with; zooming in re-rasterises. |
| 42 | let long = size[0].max(size[1]).min(opts.target.max(16)); |
| 43 | Ok(svg.rasterize(long)) |
| 44 | } |
| 45 | |
| 46 | impl Svg { |
| 47 | /// Render with the longer side `long` pixels. |
| 48 | pub fn rasterize(self: &Arc<Self>, long: u32) -> DecodedImage { |
| 49 | let [w, h] = self.size; |
| 50 | let k = long.clamp(1, MAX_RASTER) as f32 / w.max(h) as f32; |
| 51 | let pw = ((w as f32 * k).round() as u32).max(1); |
| 52 | let ph = ((h as f32 * k).round() as u32).max(1); |
| 53 | let pixels = match tiny_skia::Pixmap::new(pw, ph) { |
| 54 | Some(mut pixmap) => { |
| 55 | let t = |
| 56 | tiny_skia::Transform::from_scale(pw as f32 / w as f32, ph as f32 / h as f32); |
| 57 | resvg::render(&self.tree, t, &mut pixmap.as_mut()); |
| 58 | pixmap.take_demultiplied() |
| 59 | } |
| 60 | None => vec![0; pw as usize * ph as usize * 4], |
| 61 | }; |
| 62 | let mut img = DecodedImage::still([pw, ph], pixels, "SVG"); |
| 63 | img.source_size = self.size; |
| 64 | img.refine = Some(Refine::Svg(self.clone())); |
| 65 | img |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | #[cfg(test)] |
| 70 | mod tests { |
| 71 | use super::*; |
| 72 | |
| 73 | #[test] |
| 74 | fn rasterises_at_any_size() { |
| 75 | let dir = std::env::temp_dir().join(format!("remage-svg-{}", std::process::id())); |
| 76 | std::fs::create_dir_all(&dir).unwrap(); |
| 77 | let path = dir.join("a.svg"); |
| 78 | std::fs::write( |
| 79 | &path, |
| 80 | r#"<svg xmlns="http://www.w3.org/2000/svg" width="40" height="20"> |
| 81 | <rect width="20" height="20" fill="red"/></svg>"#, |
| 82 | ) |
| 83 | .unwrap(); |
| 84 | let img = decode(&path, &Options::default()).unwrap(); |
| 85 | assert_eq!((img.size, img.source_size), ([40, 20], [40, 20])); |
| 86 | assert_eq!(&img.pixels()[..4], [255, 0, 0, 255]); |
| 87 | // Transparent right half. |
| 88 | assert_eq!(img.pixels()[(30 * 4) + 3], 0); |
| 89 | let Some(Refine::Svg(svg)) = &img.refine else { |
| 90 | panic!("refinable") |
| 91 | }; |
| 92 | let big = svg.rasterize(400); |
| 93 | assert_eq!((big.size, big.source_size), ([400, 200], [40, 20])); |
| 94 | let small = decode( |
| 95 | &path, |
| 96 | &Options { |
| 97 | target: 10, |
| 98 | ..Options::default() |
| 99 | }, |
| 100 | ) |
| 101 | .unwrap(); |
| 102 | assert_eq!(small.size, [16, 8]); |
| 103 | } |
| 104 | } |