zng_ext_svg/
lib.rs

1#![doc(html_favicon_url = "https://zng-ui.github.io/res/zng-logo-icon.png")]
2#![doc(html_logo_url = "https://zng-ui.github.io/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, PxDensity2d, PxDensityUnits as _, PxSize};
18
19/// Application extension that installs SVG handling.
20///
21/// This extension installs the [`SvgRenderCache`] in [`IMAGES`] on init.
22#[derive(Default)]
23#[non_exhaustive]
24pub struct SvgManager {}
25
26impl AppExtension for SvgManager {
27    fn init(&mut self) {
28        IMAGES.install_proxy(Box::new(SvgRenderCache::default()));
29    }
30}
31
32/// Image cache proxy that handlers SVG requests.
33#[derive(Default)]
34#[non_exhaustive]
35pub struct SvgRenderCache {}
36impl ImageCacheProxy for SvgRenderCache {
37    fn data(
38        &mut self,
39        key: &ImageHash,
40        data: &[u8],
41        format: &ImageDataFormat,
42        mode: ImageCacheMode,
43        downscale: Option<ImageDownscale>,
44        mask: Option<ImageMaskMode>,
45        is_loaded: bool,
46    ) -> Option<ImageVar> {
47        let data = match format {
48            ImageDataFormat::FileExtension(txt) if txt == "svg" || txt == "svgz" => SvgData::Raw(data.to_vec()),
49            ImageDataFormat::MimeType(txt) if txt == "image/svg+xml" => SvgData::Raw(data.to_vec()),
50            ImageDataFormat::Unknown => SvgData::Str(svg_data_from_unknown(data)?),
51            _ => return None,
52        };
53        let key = if is_loaded {
54            None // already cached, return image is internal
55        } else {
56            Some(*key)
57        };
58        Some(IMAGES.image_task(async move { load(data, downscale) }, mode, key, None, None, mask))
59    }
60
61    fn is_data_proxy(&self) -> bool {
62        true
63    }
64}
65
66enum SvgData {
67    Raw(Vec<u8>),
68    Str(String),
69}
70fn load(data: SvgData, downscale: Option<ImageDownscale>) -> ImageSource {
71    let options = resvg::usvg::Options::default();
72
73    let tree = match data {
74        SvgData::Raw(data) => resvg::usvg::Tree::from_data(&data, &options),
75        SvgData::Str(data) => resvg::usvg::Tree::from_str(&data, &options),
76    };
77    match tree {
78        Ok(tree) => {
79            let mut size = tree.size().to_int_size();
80            if let Some(d) = downscale {
81                let s = d.resize_dimensions(PxSize::new(Px(size.width() as _), Px(size.height() as _)));
82                match resvg::tiny_skia::IntSize::from_wh(s.width.0 as _, s.height.0 as _) {
83                    Some(s) => size = s,
84                    None => tracing::error!("cannot resize svg to zero size"),
85                }
86            }
87            let mut pixmap = match resvg::tiny_skia::Pixmap::new(size.width(), size.height()) {
88                Some(p) => p,
89                None => return error(formatx!("can't allocate pixmap for {:?} svg", size)),
90            };
91            resvg::render(&tree, resvg::tiny_skia::Transform::identity(), &mut pixmap.as_mut());
92            let size = PxSize::new(Px(pixmap.width() as _), Px(pixmap.height() as _));
93
94            let mut data = pixmap.take();
95            for pixel in data.chunks_exact_mut(4) {
96                pixel.swap(0, 2);
97            }
98
99            ImageSource::Data(
100                ImageHash::compute(&data),
101                Arc::new(data),
102                ImageDataFormat::Bgra8 {
103                    size,
104                    density: Some(PxDensity2d::splat(options.dpi.ppi())),
105                },
106            )
107        }
108        Err(e) => error(formatx!("{e}")),
109    }
110}
111
112fn error(error: Txt) -> ImageSource {
113    ImageSource::Image(IMAGES.dummy(Some(error)))
114}
115
116fn svg_data_from_unknown(data: &[u8]) -> Option<String> {
117    if data.starts_with(&[0x1f, 0x8b]) {
118        // gzip magic number
119        let data = resvg::usvg::decompress_svgz(data).ok()?;
120        uncompressed_data_is_svg(&data)
121    } else {
122        uncompressed_data_is_svg(data)
123    }
124}
125fn uncompressed_data_is_svg(data: &[u8]) -> Option<String> {
126    let s = std::str::from_utf8(data).ok()?;
127    if s.contains("http://www.w3.org/2000/svg") {
128        Some(s.to_owned())
129    } else {
130        None
131    }
132}
zng_ext_svg/lib.rs

zng_ext_svg/
lib.rs
