zng_ext_svg/
lib.rs

Help
1#![doc(html_favicon_url = "https://raw.githubusercontent.com/zng-ui/zng/main/examples/image/res/zng-logo-icon.png")]
2#![doc(html_logo_url = "https://raw.githubusercontent.com/zng-ui/zng/main/examples/image/res/zng-logo.png")]
3//!
4//! SVG image support.
5//!
6//! # Crate
7//!
8#![doc = include_str!(concat!("../", std::env!("CARGO_PKG_README")))]
9#![warn(unused_extern_crates)]
10#![warn(missing_docs)]
11
12use std::sync::Arc;
13
14use zng_app::AppExtension;
15use zng_ext_image::*;
16use zng_txt::{Txt, formatx};
17use zng_unit::{Px, PxSize};
18
19/// Application extension that installs SVG handling.
20///
21/// This extension installs the [`SvgRenderCache`] in [`IMAGES`] on init.
22#[derive(Default)]
23pub struct SvgManager {}
24
25impl AppExtension for SvgManager {
26    fn init(&mut self) {
27        IMAGES.install_proxy(Box::new(SvgRenderCache::default()));
28    }
29}
30
31/// Image cache proxy that handlers SVG requests.
32#[derive(Default)]
33pub struct SvgRenderCache {}
34impl ImageCacheProxy for SvgRenderCache {
35    fn data(
36        &mut self,
37        key: &ImageHash,
38        data: &[u8],
39        format: &ImageDataFormat,
40        mode: ImageCacheMode,
41        downscale: Option<ImageDownscale>,
42        mask: Option<ImageMaskMode>,
43        is_loaded: bool,
44    ) -> Option<ImageVar> {
45        let data = match format {
46            ImageDataFormat::FileExtension(txt) if txt == "svg" || txt == "svgz" => SvgData::Raw(data.to_vec()),
47            ImageDataFormat::MimeType(txt) if txt == "image/svg+xml" => SvgData::Raw(data.to_vec()),
48            ImageDataFormat::Unknown => SvgData::Str(svg_data_from_unknown(data)?),
49            _ => return None,
50        };
51        let key = if is_loaded {
52            None // already cached, return image is internal
53        } else {
54            Some(*key)
55        };
56        Some(IMAGES.image_task(async move { load(data, downscale) }, mode, key, None, None, mask))
57    }
58
59    fn is_data_proxy(&self) -> bool {
60        true
61    }
62}
63
64enum SvgData {
65    Raw(Vec<u8>),
66    Str(String),
67}
68fn load(data: SvgData, downscale: Option<ImageDownscale>) -> ImageSource {
69    let options = resvg::usvg::Options::default();
70
71    let tree = match data {
72        SvgData::Raw(data) => resvg::usvg::Tree::from_data(&data, &options),
73        SvgData::Str(data) => resvg::usvg::Tree::from_str(&data, &options),
74    };
75    match tree {
76        Ok(tree) => {
77            let mut size = tree.size().to_int_size();
78            if let Some(d) = downscale {
79                let s = d.resize_dimensions(PxSize::new(Px(size.width() as _), Px(size.height() as _)));
80                match resvg::tiny_skia::IntSize::from_wh(s.width.0 as _, s.height.0 as _) {
81                    Some(s) => size = s,
82                    None => tracing::error!("cannot resize svg to zero size"),
83                }
84            }
85            let mut pixmap = match resvg::tiny_skia::Pixmap::new(size.width(), size.height()) {
86                Some(p) => p,
87                None => return error(formatx!("can't allocate pixmap for {:?} svg", size)),
88            };
89            resvg::render(&tree, resvg::tiny_skia::Transform::identity(), &mut pixmap.as_mut());
90            let size = PxSize::new(Px(pixmap.width() as _), Px(pixmap.height() as _));
91
92            let mut data = pixmap.take();
93            for pixel in data.chunks_exact_mut(4) {
94                pixel.swap(0, 2);
95            }
96
97            ImageSource::Data(
98                ImageHash::compute(&data),
99                Arc::new(data),
100                ImageDataFormat::Bgra8 {
101                    size,
102                    ppi: Some(ImagePpi::splat(options.dpi)),
103                },
104            )
105        }
106        Err(e) => error(formatx!("{e}")),
107    }
108}
109
110fn error(error: Txt) -> ImageSource {
111    ImageSource::Image(IMAGES.dummy(Some(error)))
112}
113
114fn svg_data_from_unknown(data: &[u8]) -> Option<String> {
115    if data.starts_with(&[0x1f, 0x8b]) {
116        // gzip magic number
117        let data = resvg::usvg::decompress_svgz(data).ok()?;
118        uncompressed_data_is_svg(&data)
119    } else {
120        uncompressed_data_is_svg(data)
121    }
122}
123fn uncompressed_data_is_svg(data: &[u8]) -> Option<String> {
124    let s = std::str::from_utf8(data).ok()?;
125    if s.contains("http://www.w3.org/2000/svg") {
126        Some(s.to_owned())
127    } else {
128        None
129    }
130}
zng_ext_svg/lib.rs

zng_ext_svg/
lib.rs
