Minimum PDF/A support (#81)

Author: laurmaedje

Cargo.lock

@@ -22,13 +22,13 @@ image = { version = "0.25", default-features = false, features = ["jpeg", "png",
 miniz_oxide = "0.8"
 once_cell = "1.18"
 oxipng = { version = "9", default-features = false, features = ["filetime", "parallel", "zopfli"] }
-pdf-writer = "0.10"
+pdf-writer = "0.12"
 pdfium-render = "=0.8.20"
 termcolor = "1.2"
 usvg = { version = "0.43", default-features = false }
 tiny-skia = "0.11.4"
 resvg = { version = "0.43", default-features = false }
-subsetter = { git = "https://github.com/typst/subsetter", rev = "4e0058b" }
+subsetter = "0.2"
 ttf-parser = { version = "0.24.1" }
 siphasher = { version = "1.0.1"}
 

Cargo.toml

@@ -27,6 +27,7 @@ fn run() -> Result<(), String> {
             compress: true,
             embed_text: !args.text_to_paths,
             raster_scale: args.raster_scale,
+            pdfa: false,
         };
 
         let page_options = PageOptions { dpi: args.dpi };

cli/src/main.rs

@@ -67,7 +67,7 @@ use usvg::{Size, Transform, Tree};
 
 use crate::render::{tree_to_stream, tree_to_xobject};
 use crate::util::context::Context;
-use crate::util::helper::{deflate, RectExt, TransformExt};
+use crate::util::helper::{deflate, ContentExt, RectExt, TransformExt};
 use crate::util::resources::ResourceContainer;
 
 // The ICC profiles.
@@ -96,6 +96,11 @@ impl Default for PageOptions {
 pub enum ConversionError {
     /// The SVG image contains an unrecognized type of image.
     InvalidImage,
+    /// Text shaping resulted in a .notdef glyph. Can only occur if PDF/A
+    /// processing is enabled.
+    MissingGlyphs,
+    /// Converting the SVG would require too much nesting depth.
+    TooMuchNesting,
     /// An unknown error occurred during the conversion. This could indicate a bug in the
     /// svg2pdf.
     UnknownError,
@@ -111,6 +116,8 @@ impl Display for ConversionError {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
             Self::InvalidImage => f.write_str("An unknown type of image appears in the SVG."),
+            Self::MissingGlyphs => f.write_str("A piece of text could not be displayed with any font."),
+            Self::TooMuchNesting => f.write_str("The SVG's nesting depth is too high."),
             Self::UnknownError => f.write_str("An unknown error occurred during the conversion. This could indicate a bug in svg2pdf"),
             #[cfg(feature = "text")]
             Self::SubsetError(_) => f.write_str("An error occurred while subsetting a font."),
@@ -148,6 +155,13 @@ pub struct ConversionOptions {
     ///
     /// _Default:_ `true`.
     pub embed_text: bool,
+
+    /// Whether to write chunks in PDF/A-2b compliant mode.
+    ///
+    /// **Note:** This currently only ensures that `to_chunk` does not generate
+    /// anything that is forbidden by PDF/A. It does _not_ turn the
+    /// free-standing PDF generated by `to_pdf` into a valid PDF/A.
+    pub pdfa: bool,
 }
 
 impl Default for ConversionOptions {
@@ -156,6 +170,7 @@ impl Default for ConversionOptions {
             compress: true,
             raster_scale: 1.5,
             embed_text: true,
+            pdfa: false,
         }
     }
 }
@@ -190,7 +205,7 @@ pub fn to_pdf(
     conversion_options: ConversionOptions,
     page_options: PageOptions,
 ) -> Result<Vec<u8>> {
-    let mut ctx = Context::new(tree, conversion_options);
+    let mut ctx = Context::new(tree, conversion_options)?;
     let mut pdf = Pdf::new();
 
     let dpi_ratio = 72.0 / page_options.dpi;
@@ -210,7 +225,7 @@ pub fn to_pdf(
     // Generate main content
     let mut rc = ResourceContainer::new();
     let mut content = Content::new();
-    content.save_state();
+    content.save_state_checked()?;
     content.transform(dpi_transform.to_pdf_transform());
     tree_to_stream(tree, &mut pdf, &mut content, &mut ctx, &mut rc)?;
     content.restore_state();
@@ -347,7 +362,7 @@ pub fn to_chunk(
 ) -> Result<(Chunk, Ref)> {
     let mut chunk = Chunk::new();
 
-    let mut ctx = Context::new(tree, conversion_options);
+    let mut ctx = Context::new(tree, conversion_options)?;
     let x_ref = tree_to_xobject(tree, &mut chunk, &mut ctx)?;
     ctx.write_global_objects(&mut chunk)?;
     Ok((chunk, x_ref))

src/lib.rs

@@ -6,7 +6,9 @@ use usvg::{ClipPath, FillRule, Group, Node, Transform};
 use super::group;
 use super::path::draw_path;
 use crate::util::context::Context;
-use crate::util::helper::{bbox_to_non_zero_rect, NameExt, RectExt, TransformExt};
+use crate::util::helper::{
+    bbox_to_non_zero_rect, ContentExt, NameExt, RectExt, TransformExt,
+};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -181,7 +183,7 @@ fn create_complex_clip_path(
     let x_ref = ctx.alloc_ref();
 
     let mut content = Content::new();
-    content.save_state();
+    content.save_state_checked()?;
 
     if let Some(clip_path) = clip_path.clip_path() {
         render(parent, clip_path, chunk, &mut content, ctx, &mut rc)?;

src/render/clip_path.rs

@@ -7,7 +7,9 @@ use usvg::{Opacity, Transform};
 use super::filter;
 use super::{clip_path, mask, Render};
 use crate::util::context::Context;
-use crate::util::helper::{BlendModeExt, GroupExt, NameExt, RectExt, TransformExt};
+use crate::util::helper::{
+    BlendModeExt, ContentExt, GroupExt, NameExt, RectExt, TransformExt,
+};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -36,7 +38,7 @@ pub fn render(
     let initial_opacity = initial_opacity.unwrap_or(Opacity::ONE);
 
     if group.is_isolated() || initial_opacity.get() != 1.0 {
-        content.save_state();
+        content.save_state_checked()?;
         let gs_ref = ctx.alloc_ref();
         let mut gs = chunk.ext_graphics(gs_ref);
         gs.non_stroking_alpha(group.opacity().mul(initial_opacity).get())
@@ -126,7 +128,7 @@ fn create_to_stream(
     accumulated_transform: Transform,
     rc: &mut ResourceContainer,
 ) -> Result<()> {
-    content.save_state();
+    content.save_state_checked()?;
     content.transform(group.transform().to_pdf_transform());
     let accumulated_transform = accumulated_transform.pre_concat(group.transform());
 

src/render/group.rs

@@ -8,7 +8,7 @@ use usvg::{ImageKind, Rect, Size, Transform, Tree};
 
 use crate::render::tree_to_xobject;
 use crate::util::context::Context;
-use crate::util::helper::{NameExt, TransformExt};
+use crate::util::helper::{ContentExt, NameExt, TransformExt};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -59,7 +59,7 @@ pub fn render(
         Rect::from_xywh(0.0, 0.0, image_size.width(), image_size.height()).unwrap(),
     );
 
-    content.save_state();
+    content.save_state_checked()?;
 
     // Account for the x/y of the viewbox.
     content.transform(

src/render/image.rs

@@ -3,7 +3,7 @@ use usvg::{Group, Mask, Transform};
 
 use super::group;
 use crate::util::context::Context;
-use crate::util::helper::{clip_to_rect, MaskTypeExt, NameExt, RectExt};
+use crate::util::helper::{clip_to_rect, ContentExt, MaskTypeExt, NameExt, RectExt};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -34,7 +34,7 @@ pub fn create(
     let mut rc = ResourceContainer::new();
 
     let mut content = Content::new();
-    content.save_state();
+    content.save_state_checked()?;
 
     if let Some(mask) = mask.mask() {
         render(parent, mask, chunk, &mut content, ctx, &mut rc)?;

src/render/mask.rs

@@ -2,7 +2,7 @@ use pdf_writer::{Chunk, Content, Filter, Finish, Ref};
 use usvg::{Node, Transform, Tree};
 
 use crate::util::context::Context;
-use crate::util::helper::{RectExt, TransformExt};
+use crate::util::helper::{ContentExt, RectExt, TransformExt};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -28,7 +28,7 @@ pub fn tree_to_stream(
     ctx: &mut Context,
     rc: &mut ResourceContainer,
 ) -> Result<()> {
-    content.save_state();
+    content.save_state_checked()?;
 
     // From PDF coordinate system to SVG coordinate system
     let initial_transform =

src/render/mod.rs

@@ -8,7 +8,7 @@ use usvg::{Stroke, Transform};
 
 use super::{gradient, pattern};
 use crate::util::context::Context;
-use crate::util::helper::{ColorExt, LineCapExt, LineJoinExt, NameExt};
+use crate::util::helper::{ColorExt, ContentExt, LineCapExt, LineJoinExt, NameExt};
 use crate::util::resources::ResourceContainer;
 use crate::Result;
 
@@ -104,6 +104,7 @@ pub(crate) fn stroke_path(
     let operation = |content: &mut Content, stroke: &Stroke| {
         draw_path(path.data().segments(), content);
         finish_path(Some(stroke), None, content);
+        Ok(())
     };
 
     if let Some(path_stroke) = path.stroke() {
@@ -131,13 +132,13 @@ pub(crate) fn stroke(
     content: &mut Content,
     ctx: &mut Context,
     rc: &mut ResourceContainer,
-    operation: impl Fn(&mut Content, &Stroke),
+    operation: impl Fn(&mut Content, &Stroke) -> Result<()>,
     accumulated_transform: Transform,
     bbox: Rect,
 ) -> Result<()> {
     let paint = &stroke.paint();
 
-    content.save_state();
+    content.save_state_checked()?;
 
     match paint {
         Paint::Color(c) => {
@@ -206,7 +207,7 @@ pub(crate) fn stroke(
         content.set_dash_pattern(vec![], 0.0);
     }
 
-    operation(content, stroke);
+    operation(content, stroke)?;
 
     content.restore_state();
 
@@ -229,6 +230,7 @@ pub(crate) fn fill_path(
     let operation = |content: &mut Content, fill: &Fill| {
         draw_path(path.data().segments(), content);
         finish_path(None, Some(fill), content);
+        Ok(())
     };
 
     if let Some(path_fill) = path.fill() {
@@ -256,13 +258,13 @@ pub(crate) fn fill(
     content: &mut Content,
     ctx: &mut Context,
     rc: &mut ResourceContainer,
-    operation: impl Fn(&mut Content, &Fill),
+    operation: impl Fn(&mut Content, &Fill) -> Result<()>,
     accumulated_transform: Transform,
     bbox: Rect,
 ) -> Result<()> {
     let paint = &fill.paint();
 
-    content.save_state();
+    content.save_state_checked()?;
 
     match paint {
         Paint::Color(c) => {
@@ -307,7 +309,7 @@ pub(crate) fn fill(
         }
     }
 
-    operation(content, fill);
+    operation(content, fill)?;
     content.restore_state();
 
     Ok(())