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use base64::Engine;
use ecow::{eco_format, EcoString};
use image::{codecs::png::PngEncoder, ImageEncoder};
use typst_library::foundations::Smart;
use typst_library::layout::{Abs, Axes};
use typst_library::visualize::{
ExchangeFormat, Image, ImageKind, ImageScaling, RasterFormat,
};
use crate::SVGRenderer;
impl SVGRenderer {
/// Render an image element.
pub(super) fn render_image(&mut self, image: &Image, size: &Axes<Abs>) {
let url = convert_image_to_base64_url(image);
self.xml.start_element("image");
self.xml.write_attribute("xlink:href", &url);
self.xml.write_attribute("width", &size.x.to_pt());
self.xml.write_attribute("height", &size.y.to_pt());
self.xml.write_attribute("preserveAspectRatio", "none");
if let Some(value) = convert_image_scaling(image.scaling()) {
self.xml
.write_attribute("style", &format_args!("image-rendering: {value}"))
}
self.xml.end_element();
}
}
/// Converts an image scaling to a CSS `image-rendering` propery value.
pub fn convert_image_scaling(scaling: Smart<ImageScaling>) -> Option<&'static str> {
match scaling {
Smart::Auto => None,
Smart::Custom(ImageScaling::Smooth) => {
// This is still experimental and not implemented in all major browsers.
// https://developer.mozilla.org/en-US/docs/Web/CSS/image-rendering#browser_compatibility
Some("smooth")
}
Smart::Custom(ImageScaling::Pixelated) => Some("pixelated"),
}
}
/// Encode an image into a data URL. The format of the URL is
/// `data:image/{format};base64,`.
#[comemo::memoize]
pub fn convert_image_to_base64_url(image: &Image) -> EcoString {
let mut buf;
let (format, data): (&str, &[u8]) = match image.kind() {
ImageKind::Raster(raster) => match raster.format() {
RasterFormat::Exchange(format) => (
match format {
ExchangeFormat::Png => "png",
ExchangeFormat::Jpg => "jpeg",
ExchangeFormat::Gif => "gif",
ExchangeFormat::Webp => "webp",
},
raster.data(),
),
RasterFormat::Pixel(_) => ("png", {
buf = vec![];
let mut encoder = PngEncoder::new(&mut buf);
if let Some(icc_profile) = raster.icc() {
encoder.set_icc_profile(icc_profile.to_vec()).ok();
}
raster.dynamic().write_with_encoder(encoder).unwrap();
buf.as_slice()
}),
},
ImageKind::Svg(svg) => ("svg+xml", svg.data()),
};
let mut url = eco_format!("data:image/{format};base64,");
let data = base64::engine::general_purpose::STANDARD.encode(data);
url.push_str(&data);
url
}
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