PDF Manipulation with HexaPDF

Motivation

• Many libraries/tools for PDF manipulation in other languages

  • Java: iText, Apache PDFBox, PDF Clown, JPod
  • C/C++: pdflib, qpdf, GNUpdf, hummuspdf, libharu
  • Python: PyPDF2, reportlab, pdfrw, pdfminer
  • PHP: fpdf, tcpdf, mPDF
  • …

• Support for PDF in Ruby

  • pdf-reader: can read PDFs but not write them
  • prawn: can create PDFs but has only basic reading support
  • origami: PDF read/write support, intended for auditing PDFs
  • combinepdf: basic PDF read/write functionality

Features of HexaPDF

Goal: One library for creating, manipulating, merging, extracting data from, securing and optimizing PDF files.

• Implements most of the PDF 1.7 standard in regards to reading/writing:

  • Cross-reference streams and object streams
  • Filters: ASCIIHex, ASCII85, LZW, RunLength, Flate, DCT (passthrough)
  • All password based encryption mechanisms (including PDF 2.0 compatible AES256 method)

  → Throw a valid PDF at HexaPDF and it can handle it

• PDF internal objects are represented as Ruby objects for easy manipulation

  • Semi-automatic PDF object type detection (i.e. using the best class for a certain PDF object)
  • Easily extendable without modifying core classes

Examples

1. Read, compress and write a PDF:

   HexaPDF::PDF::Document.open(ARGV.shift) do |doc|
     doc.task(:optimize, compact: true, object_streams: :generate)
     doc.write(ARGV.shift, validate: true)
   end
   

2. Merge two (or more) PDFs:

   target = HexaPDF::PDF::Document.new
   output_name = ARGV.shift
   ARGV.each do |file|
     pdf = HexaPDF::PDF::Document.new(io: File.open(file, 'rb'))
     pdf.pages.each_page {|page| target.pages.add_page(target.import(page))}
   end
   target.write(output_name)
   

3. Graphics support (https://gist.github.com/gettalong/7c72149ee84ea9d01b61)

Performance

• Good performance and low memory usage

• Even better performance if StringScanner would natively support reading integers, floats and symbols (currently a throw-away string needs to be created)

• Comparison for read-compress-write (full output see https://gist.github.com/gettalong/8955ff5403fe7abb7bee)

  | a.pdf                |     Time |     Memory |   File size |        | c.pdf                |     Time |     Memory |   File size |
  |------------------------------------------------------------|        |------------------------------------------------------------|
  | hexapdf              |     87ms |  14.012KiB |      49.188 |        | hexapdf              |  1.909ms |  45.268KiB |  13.229.244 |
  | hexapdf -cp          |    113ms |  14.540KiB |      48.252 |        | hexapdf -cp          | 10.086ms | 101.128KiB |  13.136.319 |
  | origami              |    309ms |  26.116KiB |      52.313 |        | origami              |  8.386ms | 173.236KiB |  14.338.620 |
  | pdftk                |     40ms |  53.336KiB |      53.144 |        | pdftk                |  1.643ms | 100.656KiB |  14.439.611 |
  | qpdf-comp            |     11ms |   4.276KiB |      49.287 |        | qpdf-comp            |  2.246ms |  36.648KiB |  13.228.102 |
  | smpdf                |     16ms |   8.124KiB |      48.329 |        | smpdf                |  3.169ms |  75.768KiB |  13.076.598 |
    
    
  | d.pdf                |     Time |     Memory |   File size |        | e.pdf                |     Time |     Memory |   File size |
  |------------------------------------------------------------|        |------------------------------------------------------------|
  | hexapdf              |  7.674ms |  98.592KiB |   6.784.251 |        | hexapdf              |  1.006ms |  46.960KiB |  21.770.465 |
  | hexapdf -cp          |  5.997ms | 102.812KiB |   5.532.779 |        | hexapdf -cp          | 35.707ms | 190.528KiB |  21.197.170 |
  | origami              | 22.835ms | 192.256KiB |   7.499.292 |        | origami              |  3.301ms | 153.628KiB |  21.796.847 |
  | pdftk                |  2.281ms | 102.584KiB |   7.279.035 |        | pdftk                |    681ms | 123.152KiB |  21.874.883 |
  | qpdf-comp            |  3.224ms |  45.836KiB |   6.703.374 |        | qpdf-comp            |  1.517ms |  65.172KiB |  21.787.558 |
  | smpdf                |  2.803ms |  80.416KiB |   5.528.352 |        | smpdf                | 37.539ms | 647.440KiB |  21.188.516 |
  

Future

• Support for various font formats (Type1, CFF, TTF, OpenType)

• Showing text on a page in addition to graphics

• Nicer methods for modifying the PDF object tree

Caveat: Code of HexaPDF not released yet but soon

Thanks!