Include images from raw pixmaps and more (#5632)

Co-authored-by: PgBiel <9021226+PgBiel@users.noreply.github.com>
Co-authored-by: Laurenz <laurmaedje@gmail.com>

1 files changed, 88 insertions, 77 deletions

diff --git a/crates/typst-pdf/src/image.rs b/crates/typst-pdf/src/image.rs
index bff7bfef..550f60a4 100644
--- a/crates/typst-pdf/src/image.rs
+++ b/crates/typst-pdf/src/image.rs
@@ -5,8 +5,10 @@ use ecow::eco_format;
 use image::{DynamicImage, GenericImageView, Rgba};
 use pdf_writer::{Chunk, Filter, Finish, Ref};
 use typst_library::diag::{At, SourceResult, StrResult};
+use typst_library::foundations::Smart;
 use typst_library::visualize::{
-    ColorSpace, Image, ImageKind, RasterFormat, RasterImage, SvgImage,
+    ColorSpace, ExchangeFormat, Image, ImageKind, ImageScaling, RasterFormat,
+    RasterImage, SvgImage,
 };
 use typst_utils::Deferred;
 
@@ -32,11 +34,13 @@ pub fn write_images(
                 EncodedImage::Raster {
                     data,
                     filter,
-                    has_color,
+                    color_space,
+                    bits_per_component,
                     width,
                     height,
-                    icc,
+                    compressed_icc,
                     alpha,
+                    interpolate,
                 } => {
                     let image_ref = chunk.alloc();
                     out.insert(image.clone(), image_ref);
@@ -45,23 +49,18 @@ pub fn write_images(
                     image.filter(*filter);
                     image.width(*width as i32);
                     image.height(*height as i32);
-                    image.bits_per_component(8);
+                    image.bits_per_component(i32::from(*bits_per_component));
+                    image.interpolate(*interpolate);
 
                     let mut icc_ref = None;
                     let space = image.color_space();
-                    if icc.is_some() {
+                    if compressed_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,
+                            *color_space,
                             space,
                             &context.globals.color_functions,
                         );
@@ -79,20 +78,27 @@ pub fn write_images(
                         mask.width(*width as i32);
                         mask.height(*height as i32);
                         mask.color_space().device_gray();
-                        mask.bits_per_component(8);
+                        mask.bits_per_component(i32::from(*bits_per_component));
+                        mask.interpolate(*interpolate);
                     } else {
                         image.finish();
                     }
 
-                    if let (Some(icc), Some(icc_ref)) = (icc, icc_ref) {
-                        let mut stream = chunk.icc_profile(icc_ref, icc);
+                    if let (Some(compressed_icc), Some(icc_ref)) =
+                        (compressed_icc, icc_ref)
+                    {
+                        let mut stream = chunk.icc_profile(icc_ref, compressed_icc);
                         stream.filter(Filter::FlateDecode);
-                        if *has_color {
-                            stream.n(3);
-                            stream.alternate().srgb();
-                        } else {
-                            stream.n(1);
-                            stream.alternate().d65_gray();
+                        match color_space {
+                            ColorSpace::Srgb => {
+                                stream.n(3);
+                                stream.alternate().srgb();
+                            }
+                            ColorSpace::D65Gray => {
+                                stream.n(1);
+                                stream.alternate().d65_gray();
+                            }
+                            _ => unimplemented!(),
                         }
                     }
                 }
@@ -122,35 +128,17 @@ pub fn deferred_image(
 ) -> (Deferred<StrResult<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)
-            }
+            Some(to_color_space(raster.dynamic().color()))
         }
         _ => None,
     };
 
+    // PDF/A does not appear to allow interpolation.
+    // See https://github.com/typst/typst/issues/2942.
+    let interpolate = !pdfa && image.scaling() == Smart::Custom(ImageScaling::Smooth);
+
     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));
-
-            Ok(EncodedImage::Raster {
-                data,
-                filter,
-                has_color,
-                width,
-                height,
-                icc,
-                alpha,
-            })
-        }
+        ImageKind::Raster(raster) => Ok(encode_raster_image(raster, interpolate)),
         ImageKind::Svg(svg) => {
             let (chunk, id) = encode_svg(svg, pdfa)
                 .map_err(|err| eco_format!("failed to convert SVG to PDF: {err}"))?;
@@ -161,42 +149,51 @@ pub fn deferred_image(
     (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.
+/// Encode an image with a suitable filter.
 #[typst_macros::time(name = "encode raster image")]
-fn encode_raster_image(image: &RasterImage) -> (Vec<u8>, Filter, bool) {
+fn encode_raster_image(image: &RasterImage, interpolate: bool) -> EncodedImage {
     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()),
+    let color_space = to_color_space(dynamic.color());
+
+    let (filter, data, bits_per_component) =
+        if image.format() == RasterFormat::Exchange(ExchangeFormat::Jpg) {
+            let mut data = Cursor::new(vec![]);
+            dynamic.write_to(&mut data, image::ImageFormat::Jpeg).unwrap();
+            (Filter::DctDecode, data.into_inner(), 8)
+        } else {
+            // TODO: Encode flate streams with PNG-predictor?
+            let (data, bits_per_component) = match (dynamic, color_space) {
+                // RGB image.
+                (DynamicImage::ImageRgb8(rgb), _) => (deflate(rgb.as_raw()), 8),
+                // Grayscale image
+                (DynamicImage::ImageLuma8(luma), _) => (deflate(luma.as_raw()), 8),
+                (_, ColorSpace::D65Gray) => (deflate(dynamic.to_luma8().as_raw()), 8),
+                // Anything else
+                _ => (deflate(dynamic.to_rgb8().as_raw()), 8),
+            };
+            (Filter::FlateDecode, data, bits_per_component)
         };
-        (data, Filter::FlateDecode, has_color)
+
+    let compressed_icc = image.icc().map(|data| deflate(data));
+    let alpha = dynamic.color().has_alpha().then(|| encode_alpha(dynamic));
+
+    EncodedImage::Raster {
+        data,
+        filter,
+        color_space,
+        bits_per_component,
+        width: image.width(),
+        height: image.height(),
+        compressed_icc,
+        alpha,
+        interpolate,
     }
 }
 
 /// 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();
+fn encode_alpha(image: &DynamicImage) -> (Vec<u8>, Filter) {
+    let pixels: Vec<_> = image.pixels().map(|(_, _, Rgba([_, _, _, a]))| a).collect();
     (deflate(&pixels), Filter::FlateDecode)
 }
 
@@ -224,19 +221,33 @@ pub enum EncodedImage {
         data: Vec<u8>,
         /// The filter to use for the image.
         filter: Filter,
-        /// Whether the image has color.
-        has_color: bool,
+        /// Which color space this image is encoded in.
+        color_space: ColorSpace,
+        /// How many bits of each color component are stored.
+        bits_per_component: u8,
         /// 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 image's ICC profile, deflated, if any.
+        compressed_icc: Option<Vec<u8>>,
         /// The alpha channel of the image, pre-deflated, if any.
         alpha: Option<(Vec<u8>, Filter)>,
+        /// Whether image interpolation should be enabled.
+        interpolate: bool,
     },
     /// A vector graphic.
     ///
     /// The chunk is the SVG converted to PDF objects.
     Svg(Chunk, Ref),
 }
+
+/// Matches an [`image::ColorType`] to [`ColorSpace`].
+fn to_color_space(color: image::ColorType) -> ColorSpace {
+    use image::ColorType::*;
+    match color {
+        L8 | La8 | L16 | La16 => ColorSpace::D65Gray,
+        Rgb8 | Rgba8 | Rgb16 | Rgba16 | Rgb32F | Rgba32F => ColorSpace::Srgb,
+        _ => unimplemented!(),
+    }
+}