JotPDF

Streaming PDF writer DSL for Ruby. Check out a live-editing demo with ruby.wasm: https://jotpdf.coord-e.dev/

JotPDF is in its early stages, and the API is fairly unstable.

# Gemfile
gem 'jot_pdf'

JotPDF offers two types of DSLs. One is JotPDF::Core, a low-level API that directly exposes the structure of PDFs. The other is JotPDF::Document, a relatively high-level API built on top of JotPDF::Core, designed to be useful for actual document generation.

A PDF consists of a header, object definitions, xref (cross-reference table), and a trailer (including trailer, startxref, and an EOF marker).

require "jot_pdf"

JotPDF::Core.write($stdout) do
  header

  # Emit your objects here

  xref
  trailer do
  end
end

Use obj to define an object; it returns a reference to the object.

require "jot_pdf"

JotPDF::Core.write($stdout) do
  header

  obj.of_dict do
    entry("Type").of_name "Pages"
    entry("Kids").of_array {}
    entry("Count").of_int 0
  end => pages_obj

  obj.of_dict do
    entry("Type").of_name "Catalog"
    entry("Pages").of_ref pages_obj
  end => catalog_obj

  xref
  trailer do
     # JotPDF automatically inserts Size entry in the trailer dictionary
    entry("Root").of_ref catalog_obj
  end
end

Use alloc_obj to declare an object and emit its contents later.

require "jot_pdf"

JotPDF::Core.write($stdout) do
  header

  alloc_obj => pages_obj

  obj.of_dict do
    entry("Type").of_name "Catalog"
    entry("Pages").of_ref pages_obj
  end => catalog_obj

  obj(pages_obj).of_dict do
    entry("Type").of_name "Pages"
    entry("Kids").of_array {}
    entry("Count").of_int 0
  end

  xref
  trailer do
    entry("Root").of_ref catalog_obj
  end
end

Use page to emit a page.

require "jot_pdf"

JotPDF::Document.write($stdout) do
  page width: 210, height: 297 do
    text "Hello, World!", x: 10, y: 200
  end
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/coord-e/jot_pdf. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the JotPDF project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.