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|
use std::io::Cursor;
use image::{DynamicImage, GenericImageView, ImageResult, Rgba};
use pdf_writer::{Filter, Finish};
use super::{deflate, PdfContext, RefExt};
use crate::image::{DecodedImage, RasterFormat};
/// Embed all used images into the PDF.
#[tracing::instrument(skip_all)]
pub fn write_images(ctx: &mut PdfContext) {
for image in ctx.image_map.items() {
let image_ref = ctx.alloc.bump();
let icc_ref = ctx.alloc.bump();
ctx.image_refs.push(image_ref);
let width = image.width();
let height = image.height();
// Add the primary image.
// TODO: Error if image could not be encoded.
match image.decoded().as_ref() {
DecodedImage::Raster(dynamic, icc, format) => {
// TODO: Error if image could not be encoded.
let (data, filter, has_color) = encode_image(*format, dynamic).unwrap();
let mut image = ctx.writer.image_xobject(image_ref, &data);
image.filter(filter);
image.width(width as i32);
image.height(height as i32);
image.bits_per_component(8);
let space = image.color_space();
if icc.is_some() {
space.icc_based(icc_ref);
} else if has_color {
space.device_rgb();
} else {
space.device_gray();
}
// Add a second gray-scale image containing the alpha values if
// this image has an alpha channel.
if dynamic.color().has_alpha() {
let (alpha_data, alpha_filter) = encode_alpha(dynamic);
let mask_ref = ctx.alloc.bump();
image.s_mask(mask_ref);
image.finish();
let mut mask = ctx.writer.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) = icc {
let compressed = deflate(&icc.0);
let mut stream = ctx.writer.icc_profile(icc_ref, &compressed);
stream.filter(Filter::FlateDecode);
if has_color {
stream.n(3);
stream.alternate().srgb();
} else {
stream.n(1);
stream.alternate().d65_gray();
}
}
}
DecodedImage::Svg(svg) => {
let next_ref = svg2pdf::convert_tree_into(
svg,
svg2pdf::Options::default(),
&mut ctx.writer,
image_ref,
);
ctx.alloc = next_ref;
}
}
}
}
/// 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.
#[tracing::instrument(skip_all)]
fn encode_image(
format: RasterFormat,
dynamic: &DynamicImage,
) -> ImageResult<(Vec<u8>, Filter, bool)> {
Ok(match (format, dynamic) {
// 8-bit gray JPEG.
(RasterFormat::Jpg, DynamicImage::ImageLuma8(_)) => {
let mut data = Cursor::new(vec![]);
dynamic.write_to(&mut data, image::ImageFormat::Jpeg)?;
(data.into_inner(), Filter::DctDecode, false)
}
// 8-bit RGB JPEG (CMYK JPEGs get converted to RGB earlier).
(RasterFormat::Jpg, DynamicImage::ImageRgb8(_)) => {
let mut data = Cursor::new(vec![]);
dynamic.write_to(&mut data, image::ImageFormat::Jpeg)?;
(data.into_inner(), Filter::DctDecode, true)
}
// TODO: Encode flate streams with PNG-predictor?
// 8-bit gray PNG.
(RasterFormat::Png, DynamicImage::ImageLuma8(luma)) => {
let data = deflate(luma.as_raw());
(data, Filter::FlateDecode, false)
}
// Anything else (including Rgb(a) PNGs).
(_, buf) => {
let (width, height) = buf.dimensions();
let mut pixels = Vec::with_capacity(3 * width as usize * height as usize);
for (_, _, Rgba([r, g, b, _])) in buf.pixels() {
pixels.push(r);
pixels.push(g);
pixels.push(b);
}
let data = deflate(&pixels);
(data, Filter::FlateDecode, true)
}
})
}
/// Encode an image's alpha channel if present.
#[tracing::instrument(skip_all)]
fn encode_alpha(dynamic: &DynamicImage) -> (Vec<u8>, Filter) {
let pixels: Vec<_> = dynamic.pixels().map(|(_, _, Rgba([_, _, _, a]))| a).collect();
(deflate(&pixels), Filter::FlateDecode)
}
|
