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use std::collections::HashMap;
use std::io::Cursor;
use image::{DynamicImage, GenericImageView, Rgba};
use pdf_writer::{Chunk, Filter, Finish, Ref};
use typst::utils::Deferred;
use typst::visualize::{
ColorSpace, Image, ImageKind, RasterFormat, RasterImage, SvgImage,
};
use crate::{color, deflate, PdfChunk, WithGlobalRefs};
/// Embed all used images into the PDF.
#[typst_macros::time(name = "write images")]
pub fn write_images(context: &WithGlobalRefs) -> (PdfChunk, HashMap<Image, Ref>) {
let mut chunk = PdfChunk::new();
let mut out = HashMap::new();
context.resources.traverse(&mut |resources| {
for (i, image) in resources.images.items().enumerate() {
if out.contains_key(image) {
continue;
}
let handle = resources.deferred_images.get(&i).unwrap();
match handle.wait() {
EncodedImage::Raster {
data,
filter,
has_color,
width,
height,
icc,
alpha,
} => {
let image_ref = chunk.alloc();
out.insert(image.clone(), image_ref);
let mut image = chunk.chunk.image_xobject(image_ref, data);
image.filter(*filter);
image.width(*width as i32);
image.height(*height as i32);
image.bits_per_component(8);
let mut icc_ref = None;
let space = image.color_space();
if icc.is_some() {
let id = chunk.alloc.bump();
space.icc_based(id);
icc_ref = Some(id);
} else if *has_color {
color::write(
ColorSpace::Srgb,
space,
&context.globals.color_functions,
);
} else {
color::write(
ColorSpace::D65Gray,
space,
&context.globals.color_functions,
);
}
// Add a second gray-scale image containing the alpha values if
// this image has an alpha channel.
if let Some((alpha_data, alpha_filter)) = alpha {
let mask_ref = chunk.alloc.bump();
image.s_mask(mask_ref);
image.finish();
let mut mask = chunk.image_xobject(mask_ref, alpha_data);
mask.filter(*alpha_filter);
mask.width(*width as i32);
mask.height(*height as i32);
mask.color_space().device_gray();
mask.bits_per_component(8);
} else {
image.finish();
}
if let (Some(icc), Some(icc_ref)) = (icc, icc_ref) {
let mut stream = chunk.icc_profile(icc_ref, icc);
stream.filter(Filter::FlateDecode);
if *has_color {
stream.n(3);
stream.alternate().srgb();
} else {
stream.n(1);
stream.alternate().d65_gray();
}
}
}
EncodedImage::Svg(svg_chunk, id) => {
let mut map = HashMap::new();
svg_chunk.renumber_into(&mut chunk.chunk, |old| {
*map.entry(old).or_insert_with(|| chunk.alloc.bump())
});
out.insert(image.clone(), map[id]);
}
}
}
});
(chunk, out)
}
/// Creates a new PDF image from the given image.
///
/// Also starts the deferred encoding of the image.
#[comemo::memoize]
pub fn deferred_image(image: Image) -> (Deferred<EncodedImage>, Option<ColorSpace>) {
let color_space = match image.kind() {
ImageKind::Raster(raster) if raster.icc().is_none() => {
if raster.dynamic().color().channel_count() > 2 {
Some(ColorSpace::Srgb)
} else {
Some(ColorSpace::D65Gray)
}
}
_ => None,
};
let deferred = Deferred::new(move || match image.kind() {
ImageKind::Raster(raster) => {
let raster = raster.clone();
let (width, height) = (raster.width(), raster.height());
let (data, filter, has_color) = encode_raster_image(&raster);
let icc = raster.icc().map(deflate);
let alpha =
raster.dynamic().color().has_alpha().then(|| encode_alpha(&raster));
EncodedImage::Raster { data, filter, has_color, width, height, icc, alpha }
}
ImageKind::Svg(svg) => {
let (chunk, id) = encode_svg(svg);
EncodedImage::Svg(chunk, id)
}
});
(deferred, color_space)
}
/// Encode an image with a suitable filter and return the data, filter and
/// whether the image has color.
///
/// Skips the alpha channel as that's encoded separately.
#[typst_macros::time(name = "encode raster image")]
fn encode_raster_image(image: &RasterImage) -> (Vec<u8>, Filter, bool) {
let dynamic = image.dynamic();
let channel_count = dynamic.color().channel_count();
let has_color = channel_count > 2;
if image.format() == RasterFormat::Jpg {
let mut data = Cursor::new(vec![]);
dynamic.write_to(&mut data, image::ImageFormat::Jpeg).unwrap();
(data.into_inner(), Filter::DctDecode, has_color)
} else {
// TODO: Encode flate streams with PNG-predictor?
let data = match (dynamic, channel_count) {
(DynamicImage::ImageLuma8(luma), _) => deflate(luma.as_raw()),
(DynamicImage::ImageRgb8(rgb), _) => deflate(rgb.as_raw()),
// Grayscale image
(_, 1 | 2) => deflate(dynamic.to_luma8().as_raw()),
// Anything else
_ => deflate(dynamic.to_rgb8().as_raw()),
};
(data, Filter::FlateDecode, has_color)
}
}
/// Encode an image's alpha channel if present.
#[typst_macros::time(name = "encode alpha")]
fn encode_alpha(raster: &RasterImage) -> (Vec<u8>, Filter) {
let pixels: Vec<_> = raster
.dynamic()
.pixels()
.map(|(_, _, Rgba([_, _, _, a]))| a)
.collect();
(deflate(&pixels), Filter::FlateDecode)
}
/// Encode an SVG into a chunk of PDF objects.
#[typst_macros::time(name = "encode svg")]
fn encode_svg(svg: &SvgImage) -> (Chunk, Ref) {
// TODO: Don't unwrap once we have export diagostics.
svg2pdf::to_chunk(svg.tree(), svg2pdf::ConversionOptions::default()).unwrap()
}
/// A pre-encoded image.
pub enum EncodedImage {
/// A pre-encoded rasterized image.
Raster {
/// The raw, pre-deflated image data.
data: Vec<u8>,
/// The filter to use for the image.
filter: Filter,
/// Whether the image has color.
has_color: bool,
/// The image's width.
width: u32,
/// The image's height.
height: u32,
/// The image's ICC profile, pre-deflated, if any.
icc: Option<Vec<u8>>,
/// The alpha channel of the image, pre-deflated, if any.
alpha: Option<(Vec<u8>, Filter)>,
},
/// A vector graphic.
///
/// The chunk is the SVG converted to PDF objects.
Svg(Chunk, Ref),
}
|
