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Diffstat (limited to 'crates/typst-pdf/src/resources.rs')
| -rw-r--r-- | crates/typst-pdf/src/resources.rs | 349 |
1 files changed, 0 insertions, 349 deletions
diff --git a/crates/typst-pdf/src/resources.rs b/crates/typst-pdf/src/resources.rs deleted file mode 100644 index bdbf2f1e..00000000 --- a/crates/typst-pdf/src/resources.rs +++ /dev/null @@ -1,349 +0,0 @@ -//! PDF resources. -//! -//! Resources are defined in dictionaries. They map identifiers such as `Im0` to -//! a PDF reference. Each [content stream] is associated with a resource dictionary. -//! The identifiers defined in the resources can then be used in content streams. -//! -//! [content stream]: `crate::content` - -use std::collections::{BTreeMap, HashMap}; -use std::hash::Hash; - -use ecow::{eco_format, EcoString}; -use pdf_writer::{Dict, Finish, Name, Ref}; -use subsetter::GlyphRemapper; -use typst_library::diag::{SourceResult, StrResult}; -use typst_library::text::{Font, Lang}; -use typst_library::visualize::Image; -use typst_syntax::Span; -use typst_utils::Deferred; - -use crate::color::ColorSpaces; -use crate::color_font::ColorFontMap; -use crate::extg::ExtGState; -use crate::gradient::PdfGradient; -use crate::image::EncodedImage; -use crate::tiling::TilingRemapper; -use crate::{PdfChunk, Renumber, WithEverything, WithResources}; - -/// All the resources that have been collected when traversing the document. -/// -/// This does not allocate references to resources, only track what was used -/// and deduplicate what can be deduplicated. -/// -/// You may notice that this structure is a tree: [`TilingRemapper`] and -/// [`ColorFontMap`] (that are present in the fields of [`Resources`]), -/// themselves contain [`Resources`] (that will be called "sub-resources" from -/// now on). Because color glyphs and tilings are defined using content -/// streams, just like pages, they can refer to resources too, which are tracked -/// by the respective sub-resources. -/// -/// Each instance of this structure will become a `/Resources` dictionary in -/// the final PDF. It is not possible to use a single shared dictionary for all -/// pages, tilings and color fonts, because if a resource is listed in its own -/// `/Resources` dictionary, some PDF readers will fail to open the document. -/// -/// Because we need to lazily initialize sub-resources (we don't know how deep -/// the tree will be before reading the document), and that this is done in a -/// context where no PDF reference allocator is available, `Resources` are -/// originally created with the type parameter `R = ()`. The reference for each -/// dictionary will only be allocated in the next phase, once we know the shape -/// of the tree, at which point `R` becomes `Ref`. No other value of `R` should -/// ever exist. -pub struct Resources<R = Ref> { - /// The global reference to this resource dictionary, or `()` if it has not - /// been allocated yet. - pub reference: R, - - /// Handles color space writing. - pub colors: ColorSpaces, - - /// Deduplicates fonts used across the document. - pub fonts: Remapper<Font>, - /// Deduplicates images used across the document. - pub images: Remapper<Image>, - /// Handles to deferred image conversions. - pub deferred_images: HashMap<usize, (Deferred<StrResult<EncodedImage>>, Span)>, - /// Deduplicates gradients used across the document. - pub gradients: Remapper<PdfGradient>, - /// Deduplicates tilings used across the document. - pub tilings: Option<Box<TilingRemapper<R>>>, - /// Deduplicates external graphics states used across the document. - pub ext_gs: Remapper<ExtGState>, - /// Deduplicates color glyphs. - pub color_fonts: Option<Box<ColorFontMap<R>>>, - - // The fields below do not correspond to actual resources that will be - // written in a dictionary, but are more meta-data about resources that - // can't really live somewhere else. - /// The number of glyphs for all referenced languages in the content stream. - /// We keep track of this to determine the main document language. - /// BTreeMap is used to write sorted list of languages to metadata. - pub languages: BTreeMap<Lang, usize>, - - /// For each font a mapping from used glyphs to their text representation. - /// This is used for the PDF's /ToUnicode map, and important for copy-paste - /// and searching. - /// - /// Note that the text representation may contain multiple chars in case of - /// ligatures or similar things, and it may have no entry in the font's cmap - /// (or only a private-use codepoint), like the “Th” in Linux Libertine. - /// - /// A glyph may have multiple entries in the font's cmap, and even the same - /// glyph can have a different text representation within one document. - /// But /ToUnicode does not support that, so we just save the first occurrence. - pub glyph_sets: HashMap<Font, BTreeMap<u16, EcoString>>, - /// Same as `glyph_sets`, but for color fonts. - pub color_glyph_sets: HashMap<Font, BTreeMap<u16, EcoString>>, - /// Stores the glyph remapper for each font for the subsetter. - pub glyph_remappers: HashMap<Font, GlyphRemapper>, -} - -impl<R: Renumber> Renumber for Resources<R> { - fn renumber(&mut self, offset: i32) { - self.reference.renumber(offset); - - if let Some(color_fonts) = &mut self.color_fonts { - color_fonts.resources.renumber(offset); - } - - if let Some(tilings) = &mut self.tilings { - tilings.resources.renumber(offset); - } - } -} - -impl Default for Resources<()> { - fn default() -> Self { - Resources { - reference: (), - colors: ColorSpaces::default(), - fonts: Remapper::new("F"), - images: Remapper::new("Im"), - deferred_images: HashMap::new(), - gradients: Remapper::new("Gr"), - tilings: None, - ext_gs: Remapper::new("Gs"), - color_fonts: None, - languages: BTreeMap::new(), - glyph_sets: HashMap::new(), - color_glyph_sets: HashMap::new(), - glyph_remappers: HashMap::new(), - } - } -} - -impl Resources<()> { - /// Associate a reference with this resource dictionary (and do so - /// recursively for sub-resources). - pub fn with_refs(self, refs: &ResourcesRefs) -> Resources<Ref> { - Resources { - reference: refs.reference, - colors: self.colors, - fonts: self.fonts, - images: self.images, - deferred_images: self.deferred_images, - gradients: self.gradients, - tilings: self - .tilings - .zip(refs.tilings.as_ref()) - .map(|(p, r)| Box::new(p.with_refs(r))), - ext_gs: self.ext_gs, - color_fonts: self - .color_fonts - .zip(refs.color_fonts.as_ref()) - .map(|(c, r)| Box::new(c.with_refs(r))), - languages: self.languages, - glyph_sets: self.glyph_sets, - color_glyph_sets: self.color_glyph_sets, - glyph_remappers: self.glyph_remappers, - } - } -} - -impl<R> Resources<R> { - /// Run a function on this resource dictionary and all - /// of its sub-resources. - pub fn traverse<P>(&self, process: &mut P) -> SourceResult<()> - where - P: FnMut(&Self) -> SourceResult<()>, - { - process(self)?; - if let Some(color_fonts) = &self.color_fonts { - color_fonts.resources.traverse(process)?; - } - if let Some(tilings) = &self.tilings { - tilings.resources.traverse(process)?; - } - Ok(()) - } -} - -/// References for a resource tree. -/// -/// This structure is a tree too, that should have the same structure as the -/// corresponding `Resources`. -pub struct ResourcesRefs { - pub reference: Ref, - pub color_fonts: Option<Box<ResourcesRefs>>, - pub tilings: Option<Box<ResourcesRefs>>, -} - -impl Renumber for ResourcesRefs { - fn renumber(&mut self, offset: i32) { - self.reference.renumber(offset); - if let Some(color_fonts) = &mut self.color_fonts { - color_fonts.renumber(offset); - } - if let Some(tilings) = &mut self.tilings { - tilings.renumber(offset); - } - } -} - -/// Allocate references for all resource dictionaries. -pub fn alloc_resources_refs( - context: &WithResources, -) -> SourceResult<(PdfChunk, ResourcesRefs)> { - let mut chunk = PdfChunk::new(); - /// Recursively explore resource dictionaries and assign them references. - fn refs_for(resources: &Resources<()>, chunk: &mut PdfChunk) -> ResourcesRefs { - ResourcesRefs { - reference: chunk.alloc(), - color_fonts: resources - .color_fonts - .as_ref() - .map(|c| Box::new(refs_for(&c.resources, chunk))), - tilings: resources - .tilings - .as_ref() - .map(|p| Box::new(refs_for(&p.resources, chunk))), - } - } - - let refs = refs_for(&context.resources, &mut chunk); - Ok((chunk, refs)) -} - -/// Write the resource dictionaries that will be referenced by all pages. -/// -/// We add a reference to this dictionary to each page individually instead of -/// to the root node of the page tree because using the resource inheritance -/// feature breaks PDF merging with Apple Preview. -/// -/// Also write resource dictionaries for Type3 fonts and PDF patterns. -pub fn write_resource_dictionaries(ctx: &WithEverything) -> SourceResult<(PdfChunk, ())> { - let mut chunk = PdfChunk::new(); - let mut used_color_spaces = ColorSpaces::default(); - - ctx.resources.traverse(&mut |resources| { - used_color_spaces.merge(&resources.colors); - - let images_ref = chunk.alloc.bump(); - let patterns_ref = chunk.alloc.bump(); - let ext_gs_states_ref = chunk.alloc.bump(); - let color_spaces_ref = chunk.alloc.bump(); - - let mut color_font_slices = Vec::new(); - let mut color_font_numbers = HashMap::new(); - if let Some(color_fonts) = &resources.color_fonts { - for (_, font_slice) in color_fonts.iter() { - color_font_numbers.insert(font_slice.clone(), color_font_slices.len()); - color_font_slices.push(font_slice); - } - } - let color_font_remapper = Remapper { - prefix: "Cf", - to_pdf: color_font_numbers, - to_items: color_font_slices, - }; - - resources - .images - .write(&ctx.references.images, &mut chunk.indirect(images_ref).dict()); - - let mut patterns_dict = chunk.indirect(patterns_ref).dict(); - resources - .gradients - .write(&ctx.references.gradients, &mut patterns_dict); - if let Some(p) = &resources.tilings { - p.remapper.write(&ctx.references.tilings, &mut patterns_dict); - } - patterns_dict.finish(); - - resources - .ext_gs - .write(&ctx.references.ext_gs, &mut chunk.indirect(ext_gs_states_ref).dict()); - - let mut res_dict = chunk - .indirect(resources.reference) - .start::<pdf_writer::writers::Resources>(); - res_dict.pair(Name(b"XObject"), images_ref); - res_dict.pair(Name(b"Pattern"), patterns_ref); - res_dict.pair(Name(b"ExtGState"), ext_gs_states_ref); - res_dict.pair(Name(b"ColorSpace"), color_spaces_ref); - - // TODO: can't this be an indirect reference too? - let mut fonts_dict = res_dict.fonts(); - resources.fonts.write(&ctx.references.fonts, &mut fonts_dict); - color_font_remapper.write(&ctx.references.color_fonts, &mut fonts_dict); - fonts_dict.finish(); - - res_dict.finish(); - - let color_spaces = chunk.indirect(color_spaces_ref).dict(); - resources - .colors - .write_color_spaces(color_spaces, &ctx.globals.color_functions); - - Ok(()) - })?; - - used_color_spaces.write_functions(&mut chunk, &ctx.globals.color_functions); - - Ok((chunk, ())) -} - -/// Assigns new, consecutive PDF-internal indices to items. -pub struct Remapper<T> { - /// The prefix to use when naming these resources. - prefix: &'static str, - /// Forwards from the items to the pdf indices. - to_pdf: HashMap<T, usize>, - /// Backwards from the pdf indices to the items. - to_items: Vec<T>, -} - -impl<T> Remapper<T> -where - T: Eq + Hash + Clone, -{ - /// Create an empty mapping. - pub fn new(prefix: &'static str) -> Self { - Self { prefix, to_pdf: HashMap::new(), to_items: vec![] } - } - - /// Insert an item in the mapping if it was not already present. - pub fn insert(&mut self, item: T) -> usize { - let to_layout = &mut self.to_items; - *self.to_pdf.entry(item.clone()).or_insert_with(|| { - let pdf_index = to_layout.len(); - to_layout.push(item); - pdf_index - }) - } - - /// All items in this - pub fn items(&self) -> impl Iterator<Item = &T> + '_ { - self.to_items.iter() - } - - /// Write this list of items in a Resource dictionary. - fn write(&self, mapping: &HashMap<T, Ref>, dict: &mut Dict) { - for (number, item) in self.items().enumerate() { - let name = eco_format!("{}{}", self.prefix, number); - let reference = mapping[item]; - dict.pair(Name(name.as_bytes()), reference); - } - } -} |