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Caterpillar

This Ruby gem is a simple wrapper around the Caterpillar API. Caterpillar is a web service that allows you to convert html to pdf.

Installation

Add this line to your application's Gemfile:

gem 'caterpillar-ruby'

And then execute:

$ bundle

Or install it yourself as:

$ gem install caterpillar-ruby

Usage

Set the following attributes in you Ruby app:

Caterpillar.api_key = 'YOUR_CATERPILLAR_API_KEY' # required
Caterpillar.api_version = 'YOUR_API_VERSION' # optional, default: 'v1'
Caterpillar.base_uri = 'YOUR_API_BASE_URI' # optional, default: 'https://api.caterpillar.io'

For a Rails app you can execute:

$ rails generate caterpillar:install

or create an initializer config/initializers/caterpillar.rb:

Caterpillar.configure do |config|
  config.api_key = 'YOUR_CATERPILLAR_API_KEY'
end

Once set, you can create a PDF document by calling:

Caterpillar.create(source: content, grayscale: true, no_images: true)

You can also create test PDF documents by calling (header and footer options donot work in test mode):

Caterpillar.create(source: content, test: true)

The create call can also take a block, like so:

Caterpillar.create(source: content) do |file, response|
  # file is a tempfile holding the response body
  # response is the HTTParty response object
end

create will return an HTTParty response object, which will be the new file (or errors, if the request was not valid).

The only required parameter is:

  • :source - a string containing the HTML or URL for creating the document

For a Rails app you can pass a view as source by converting it to an HTML string using render_to_string.

You might want to set other options in that hash:

Option Type Description
:copies Number Number of copies to print into the pdf
:grayscale Boolean PDF will be generated in grayscale
:margin_bottom Number Set the page bottom margin
:margin_left Number Set the page left margin (default 10mm)
:margin_right Number Set the page right margin (default 10mm)
:margin_top Number Set the page top margin
:orientation String Set orientation to Landscape or Portrait (default Portrait)
:page_size String Set paper size to: A4, Letter, etc. (default A4)
:background Boolean Do print background (default true)
:no_background Boolean Do not print background
:disable_external_links Boolean Do not make links to remote web pages
:enable_external_links Boolean Make links to remote web pages (default true)
:disable_forms Boolean Do not turn HTML form fields into pdf form fields (default true)
:enable_forms Boolean Turn HTML form fields into pdf form fields
:images Boolean Do load or print images (default true)
:no_images Boolean Do not load or print images
:disable_internal_links Boolean Do not make local links
:enable_internal_links Boolean Make local links (default true)
:disable_javascript Boolean Do not allow web pages to run javascript
:enable_javascript Boolean Do allow web pages to run javascript (default true)
:javascript_delay Number Wait some milliseconds for javascript finish (default 200)
:viewport_size String Set viewport size if you have custom scrollbars or css attribute overflow to emulate window size
:zoom Number Use this zoom factor (default 1)
:footer_center Number/String Centered footer text
:footer_font_name Number/String Set footer font name (default Arial)
:footer_font_size Number/String Set footer font size (default 12)
:footer_html String Adds a html footer
:footer_left Number/String Left aligned footer text
:footer_line Boolean Display line above the footer
:no_footer_line Boolean Do not display line above the footer (default true)
:footer_right Number/String Right aligned footer text
:footer_spacing Number Spacing between footer and content in mm (default 0)
:header_center Number/String Centered header text
:header_font_name Number/String Set header font name (default Arial)
:header_font_size Number/String Set header font size (default 12)
:header_html String Adds a html header
:header_left Number/String Left aligned header text
:header_line Boolean Display line below the header
:no_header_line Boolean Do not display line below the header (default true)
:header_right Number/String Right aligned header text
:header_spacing Number Spacing between header and content in mm (default 0)
:password_protect Hash Refer next section for more details

Password Protect

You can password protect PDF using AES 256, AES 128, RC4 (128 & 40) encryption algorithms supported by Adobe Reader.

To encrypt PDF you need to pass :password_protect hash in the create method call along with the following required parameters:

  • :password - a string containing the secret password which will be further used to unlock the PDF
  • :key_length - a number which defines the encryption algorithm to be used. Values can be 40, 128 and 256 only.

You might want to set other options for each encryption algorithm inside :restrictions hash:

Key Length: 40

Option Value Description
:print 'y', 'n' Determines whether or not to allow printing.
:modify 'y', 'n' Determines whether or not to allow document modification.
:extract 'y', 'n' Determines whether or not to allow text/image extraction.
:annotate 'y', 'n' Determines whether or not to allow comments and form fill-in and signing.

Key Length: 128

Option Value Description
:print 'full', 'low', 'none' full: allow full printing. low: allow low-resolution printing only. none: disallow printing.
:modify 'all', 'annotate', 'form', 'assembly', 'none' all: allow full document modification. annotate: allow comment authoring and form operations. form: allow form field fill-in and signing. assembly: allow document assembly only. none: allow no modifications.
:extract 'y', 'n' Determines whether or not to allow text/image extraction.
:use_aes 'y', 'n' AES encryption will be used instead of RC4 encryption.
:accessibility 'y', 'n' Determines whether or not to allow accessibility to visually impaired.

Key Length: 256

Option Value Description
:print 'full', 'low', 'none' full: allow full printing. low: allow low-resolution printing only. none: disallow printing.
:modify 'all', 'annotate', 'form', 'assembly', 'none' all: allow full document modification. annotate: allow comment authoring and form operations. form: allow form field fill-in and signing. assembly: allow document assembly only. none: allow no modifications.
:extract 'y', 'n' Determines whether or not to allow text/image extraction.
:accessibility 'y', 'n' Determines whether or not to allow accessibility to visually impaired.

Example:

Caterpillar.create(
    source: content,
    password_protect: {
        password: 'YOUR_PASSWORD_HERE',
        key_length: 128,
        restrictions: {
            print: 'low',
            use_aes: 'y'
        }
    }
)

Meta

Maintained by KeepWorks

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/keepworks/caterpillar.

License

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