This is the beginnings of a prawn extension for adding interactive forms to PDFs.

gem install prawn-forms

Prawn-Forms depends on the core prawn library, and simply adds a few additional methods to the standard Prawn::Document object that allow you to add form elements to your output.

Start by requiring the prawn library, then the prawn-forms library. Build your PDF as usual, and use methods like text_field() to add a free text input box.

require 'prawn'
require 'prawn/forms'

Prawn::Document.generate "form.pdf" do |pdf|
  pdf.text_field("fname", 100, 560, 200, 16)
end

For further examples and documentation, check out the examples/ directory of this project and the code docs for the Prawn::Forms module.

Interactive forms are primarily defined by section 8.6 the PDF spec. The visual appearance of fields is controlled using widget annotations, defined in section 8.4.5.

A PDF can contain one form.

The form is defined by a dict linked via the AcroForm entry in the root catalog. Amongst other entries, the form dict has a Fields entry that holds an array of all the form fields. The array should be indirect references to a dicts, generally one per field.

Each field dict can link to one or more widget annotations that define the visual appearance in various states. It seems most fields have a single widget annotation, in which case it is permitted to merge the field and annotation dicts into a single dict. Annotation and field dicts have no common keys, so there is no conflict.

For the fields to appear on the page, the widget annotation (or merged field/widget dict) must appear in the page Annots entry.

This code is still very much experimental and is not recommended for use in production systems.

This library is distributed under the terms of the MIT License. See the included file for more detail.

• The source: http://github.com/yob/prawn-js/tree/master
• Prawn source: http://github.com/sandal/prawn/tree/master
• Rubyforge: http://rubyforge.org/projects/prawn