LinkThumbnailer

Ruby gem generating image thumbnails from a given URL. Rank them and give you back an object containing images and website informations. Works like Facebook link previewer.

Demo Application is here !

Features

Dead simple.
Support OpenGraph protocol.
Find and sort images that best represent what the page is about.
Find and rate description that best represent what the page is about.
Allow for custom class to sort the website descriptions yourself.
Support image urls blacklisting (advertisements).
Works with and without Rails.
Fully customizable.
Fully tested.

Installation

Add this line to your application's Gemfile:

gem 'link_thumbnailer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install link_thumbnailer

Run:

$ rails g link_thumbnailer:install

This will add link_thumbnailer.rb to config/initializers/.

Usage

Run irb and require the gem:

require 'link_thumbnailer'

The gem handle regular website but also website that use the Opengraph protocol.

object = LinkThumbnailer.generate('http://stackoverflow.com')
 => #<LinkThumbnailer::Models::Website:...>

object.title
 => "Stack Overflow"

object.description
 => "Q&A for professional and enthusiast programmers"

object.images.first.src.to_s
 => "http://cdn.sstatic.net/stackoverflow/img/[email protected]?v=fde65a5a78c6"

LinkThumbnailer generate method return an instance of LinkThumbnailer::Models::Website that respond to to_json and as_json as you would expect:

object.to_json
 => "{\"url\":\"http://stackoverflow.com\",\"title\":\"Stack Overflow\",\"description\":\"Q&A for professional and enthusiast programmers\",\"images\":[{\"src\":\"http://cdn.sstatic.net/stackoverflow/img/[email protected]?v=fde65a5a78c6\",\"size\":[316,316],\"type\":\"png\"}]}"

Configuration

LinkThumnailer comes with default configuration values. You can change default value by overriding them in a rails initializer:

In config/initializers/link_thumbnailer.rb

LinkThumbnailer.configure do |config|
  # Numbers of redirects before raising an exception when trying to parse given url.
  #
  # config.redirect_limit = 3

  # Set user agent
  #
  # config.user_agent = 'link_thumbnailer'

  # Enable or disable SSL verification
  #
  # config.verify_ssl = true

  # The amount of time in seconds to wait for a connection to be opened.
  # If the HTTP object cannot open a connection in this many seconds,
  # it raises a Net::OpenTimeout exception.
  #
  # See http://www.ruby-doc.org/stdlib-2.1.1/libdoc/net/http/rdoc/Net/HTTP.html#open_timeout
  #
  # config.http_timeout = 5

  # List of blacklisted urls you want to skip when searching for images.
  #
  # config.blacklist_urls = [
  #   %r{^http://ad\.doubleclick\.net/},
  #   %r{^http://b\.scorecardresearch\.com/},
  #   %r{^http://pixel\.quantserve\.com/},
  #   %r{^http://s7\.addthis\.com/}
  # ]

  # List of attributes you want LinkThumbnailer to fetch on a website.
  #
  # config.attributes = [:title, :images, :description]

  # List of procedures used to rate the website description. Add you custom class
  # here. Note that the order matter to compute the score. See wiki for more details
  # on how to build your own graders.
  #
  # config.graders = [
  #   ->(description) { ::LinkThumbnailer::Graders::Length.new(description) },
  #   ->(description) { ::LinkThumbnailer::Graders::HtmlAttribute.new(description, :class) },
  #   ->(description) { ::LinkThumbnailer::Graders::HtmlAttribute.new(description, :id) },
  #   ->(description) { ::LinkThumbnailer::Graders::Position.new(description) },
  #   ->(description) { ::LinkThumbnailer::Graders::LinkDensity.new(description) }
  # ]

  # Minimum description length for a website.
  #
  # config.description_min_length = 25

  # Regex of words considered positive to rate website description.
  #
  # config.positive_regex = /article|body|content|entry|hentry|main|page|pagination|post|text|blog|story/i

  # Regex of words considered negative to rate website description.
  #
  # config.negative_regex = /combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|shoutbox|sidebar|sponsor|shopping|tags|tool|widget|modal/i

  # Numbers of images to fetch. Fetching too many images will be slow.
  #
  # config.image_limit = 5
end

Or at runtime:

object = LinkThumbnailer.generate('http://stackoverflow.com', redirect_limit: 5, user_agent: 'foo')

Note that runtime options will override default global configuration.

See Configuration Options Explained for more details on each configuration options.

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Run the specs (bundle exec rspec spec)
Commit your changes (git commit -am 'Added some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request