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Diffstat (limited to 'src/pdf.rs')
| -rw-r--r-- | src/pdf.rs | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/src/pdf.rs b/src/pdf.rs new file mode 100644 index 00000000..5cdf335c --- /dev/null +++ b/src/pdf.rs @@ -0,0 +1,375 @@ +//! Writing of documents in the _PDF_ format. + +use std::io::{self, Write}; +use crate::doc::{Document, Text, DocumentFont, Size}; + + +/// A type that is a sink for types that can be written conforming +/// to the _PDF_ format (that may be things like sizes, other objects +/// or whole documents). +pub trait WritePdf<T> { + /// Write self into a byte sink, returning how many bytes were written. + fn write_pdf(&mut self, object: &T) -> io::Result<usize>; +} + +impl<W: Write> WritePdf<Document> for W { + fn write_pdf(&mut self, document: &Document) -> io::Result<usize> { + PdfWriter::new(document).write(self) + } +} + +impl<W: Write> WritePdf<Size> for W { + fn write_pdf(&mut self, size: &Size) -> io::Result<usize> { + self.write_str(size.points) + } +} + +/// A type that is a sink for types that can be converted to strings +/// and thus can be written string-like into a byte sink. +pub trait WriteByteString { + /// Write the string-like type into self, returning how many + /// bytes were written. + fn write_str<S: ToString>(&mut self, string_like: S) -> io::Result<usize>; +} + +impl<W: Write> WriteByteString for W { + fn write_str<S: ToString>(&mut self, string_like: S) -> io::Result<usize> { + self.write(string_like.to_string().as_bytes()) + } +} + + +/// Writes an abstract document into a byte sink in the _PDF_ format. +#[derive(Debug, Clone)] +struct PdfWriter<'d> { + doc: &'d Document, + w: usize, + catalog_id: u32, + page_tree_id: u32, + resources_start: u32, + pages_start: u32, + content_start: u32, + xref_table: Vec<u32>, + offset_xref: u32, +} + +impl<'d> PdfWriter<'d> { + /// Create a new pdf writer from a document. + fn new(doc: &'d Document) -> PdfWriter<'d> { + // Calculate unique ids for each object + let catalog_id: u32 = 1; + let page_tree_id = catalog_id + 1; + let pages_start = page_tree_id + 1; + let resources_start = pages_start + doc.pages.len() as u32; + let content_start = resources_start + doc.fonts.len() as u32; + + PdfWriter { + doc, + catalog_id, + page_tree_id, + resources_start, + pages_start, + content_start, + w: 0, + xref_table: vec![], + offset_xref: 0, + } + } + + /// Write the document into a byte sink. + fn write<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.write_header(target)?; + + self.write_document_catalog(target)?; + self.write_page_tree(target)?; + self.write_pages(target)?; + + self.write_resources(target)?; + + self.write_content(target)?; + // self.write_fonts(target)?; + + self.write_xref_table(target)?; + self.write_trailer(target)?; + self.write_start_xref(target)?; + + Ok(self.w) + } + + /// Write the pdf header. + fn write_header<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + // Write the magic start + self.w += target.write(b"%PDF-1.7\n")?; + Ok(self.w) + } + + /// Write the document catalog (contains general info about the document). + fn write_document_catalog<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.xref_table.push(self.w as u32); + + self.w += target.write_str(self.catalog_id)?; + self.w += target.write(b" 0 obj\n")?; + self.w += target.write(b"<<\n")?; + self.w += target.write(b"/Type /Catalog\n")?; + + self.w += target.write(b"/Pages ")?; + self.w += target.write_str(self.page_tree_id)?; + self.w += target.write(b" 0 R\n")?; + + self.w += target.write(b">>\n")?; + self.w += target.write(b"endobj\n")?; + + Ok(self.w) + } + + /// Write the page tree (overview over the pages of a document). + fn write_page_tree<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.xref_table.push(self.w as u32); + + // Create page tree + self.w += target.write_str(self.page_tree_id)?; + self.w += target.write(b" 0 obj\n")?; + self.w += target.write(b"<<\n")?; + self.w += target.write(b"/Type /Pages\n")?; + + self.w += target.write(b"/Count ")?; + self.w += target.write_str(self.doc.pages.len())?; + self.w += target.write(b"\n")?; + + self.w += target.write(b"/Kids [")?; + + for id in self.pages_start .. self.pages_start + self.doc.pages.len() as u32 { + self.w += target.write_str(id)?; + self.w += target.write(b" 0 R ")?; + } + + self.w += target.write(b"]\n")?; + + self.w += target.write(b"/Resources\n")?; + self.w += target.write(b"<<\n")?; + + self.w += target.write(b"/Font\n")?; + self.w += target.write(b"<<\n")?; + + let mut font_id = self.resources_start; + for nr in 1 ..= self.doc.fonts.len() as u32 { + self.w += target.write(b"/F")?; + self.w += target.write_str(nr)?; + self.w += target.write(b" ")?; + self.w += target.write_str(font_id)?; + self.w += target.write(b" 0 R\n")?; + font_id += 1; + } + + self.w += target.write(b">>\n")?; + self.w += target.write(b">>\n")?; + + self.w += target.write(b">>\n")?; + self.w += target.write(b"endobj\n")?; + + Ok(self.w) + } + + /// Write the page descriptions. + fn write_pages<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + let mut page_id = self.pages_start; + let mut content_id = self.content_start; + + for page in &self.doc.pages { + self.xref_table.push(self.w as u32); + + self.w += target.write_str(page_id)?; + self.w += target.write(b" 0 obj\n")?; + self.w += target.write(b"<<\n")?; + self.w += target.write(b"/Type /Page\n")?; + + self.w += target.write(b"/Parent ")?; + self.w += target.write_str(self.page_tree_id)?; + self.w += target.write(b" 0 R\n")?; + + self.w += target.write(b"/MediaBox [0 0 ")?; + self.w += target.write_pdf(&page.size[0])?; + self.w += target.write(b" ")?; + self.w += target.write_pdf(&page.size[1])?; + self.w += target.write(b"]\n")?; + + self.w += target.write(b"/Contents [")?; + + for _ in &page.contents { + self.w += target.write_str(content_id)?; + self.w += target.write(b" 0 R ")?; + + content_id += 1; + } + + self.w += target.write(b"]\n")?; + + self.w += target.write(b">>\n")?; + self.w += target.write(b"endobj\n")?; + + page_id += 1; + } + + Ok(self.w) + } + + /// Write the resources used by the file (fonts and friends). + fn write_resources<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + let mut id = self.resources_start; + + for font in &self.doc.fonts { + self.xref_table.push(self.w as u32); + + self.w += target.write_str(id)?; + self.w += target.write(b" 0 obj\n")?; + self.w += target.write(b"<<\n")?; + self.w += target.write(b"/Type /Font\n")?; + + match font { + DocumentFont::Builtin(builtin) => { + self.w += target.write(b"/Subtype /Type1\n")?; + self.w += target.write(b"/BaseFont /")?; + self.w += target.write_str(builtin.name())?; + self.w += target.write(b"\n")?; + }, + DocumentFont::Loaded(font) => { + self.w += target.write(b"/Subtype /TrueType\n")?; + self.w += target.write(b"/BaseFont /")?; + self.w += target.write_str(font.name.as_str())?; + self.w += target.write(b"\n")?; + unimplemented!(); + }, + } + + self.w += target.write(b">>\n")?; + self.w += target.write(b"endobj\n")?; + + id += 1; + } + + Ok(self.w) + } + + /// Write the page contents. + fn write_content<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + let mut id = self.content_start; + + for page in &self.doc.pages { + for content in &page.contents { + self.xref_table.push(self.w as u32); + + self.w += target.write_str(id)?; + self.w += target.write(b" 0 obj\n")?; + self.w += target.write(b"<<\n")?; + + let mut buffer = Vec::new(); + buffer.write(b"BT/\n")?; + + buffer.write(b"/F1 13 Tf\n")?; + buffer.write(b"108 734 Td\n")?; + buffer.write(b"(")?; + + let Text(string) = content; + buffer.write(string.as_bytes())?; + + buffer.write(b") Tj\n")?; + buffer.write(b"ET\n")?; + + self.w += target.write(b"/Length ")?; + self.w += target.write_str(buffer.len())?; + self.w += target.write(b"\n")?; + + self.w += target.write(b">>\n")?; + + self.w += target.write(b"stream\n")?; + self.w += target.write(&buffer)?; + self.w += target.write(b"endstream\n")?; + + self.w += target.write(b"endobj\n")?; + + id += 1; + } + } + + Ok(self.w) + } + + /// Write the cross-reference table. + fn write_xref_table<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.offset_xref = self.w as u32; + + self.w += target.write(b"xref\n")?; + self.w += target.write(b"0 ")?; + self.w += target.write_str(self.xref_table.len())?; + self.w += target.write(b"\n")?; + + self.w += target.write(b"0000000000 65535 f\r\n")?; + + for offset in &self.xref_table { + self.w += target.write(format!("{:010}", offset).as_bytes())?; + self.w += target.write(b" 00000 n")?; + self.w += target.write(b"\r\n")?; + } + + Ok(self.w) + } + + /// Write the trailer (points to the root object). + fn write_trailer<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.w += target.write(b"trailer\n")?; + self.w += target.write(b"<<\n")?; + + self.w += target.write(b"/Root ")?; + self.w += target.write_str(self.catalog_id)?; + self.w += target.write(b" 0 R\n")?; + + self.w += target.write(b"/Size ")?; + self.w += target.write_str(self.xref_table.len() + 1)?; + self.w += target.write(b"\n")?; + + self.w += target.write(b">>\n")?; + + Ok(self.w) + } + + /// Write where the cross-reference table starts. + fn write_start_xref<W: Write>(&mut self, target: &mut W) -> io::Result<usize> { + self.w += target.write(b"startxref\n")?; + self.w += target.write_str(self.offset_xref)?; + self.w += target.write(b"\n")?; + + Ok(self.w) + } +} + + +#[cfg(test)] +mod pdf_tests { + use super::*; + use crate::parsing::{Tokenize, Parse}; + use crate::doc::Generate; + + /// Create a pdf with a name from the source code. + fn test(name: &str, src: &str) { + let mut file = std::fs::File::create(name).unwrap(); + let doc = src.tokenize() + .parse().unwrap() + .generate().unwrap(); + file.write_pdf(&doc).unwrap(); + } + + #[test] + fn pdf_simple() { + test("../target/write1.pdf", "This is an example of a sentence."); + test("../target/write2.pdf"," + Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed + diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam + voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd + gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor + sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut + labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et + justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est + Lorem ipsum dolor sit amet. + "); + } +} |