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 !

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/. See #Configuration for more details.

Usage

Run irb and require the gem:

require 'rails'
 => true

require 'link_thumbnailer'
 => true

This gem can handle Opengraph protocol. Here is an example with such a website:

object = LinkThumbnailer.generate('http://zerply.com')
 => #<LinkThumbnailer::Object description="Go beyond the résumé - showcase your work and your talent" image="http://zerply.com/img/front/facebook_icon_green.png" images=["http://zerply.com/img/front/facebook_icon_green.png"] site_name="zerply.com" title="Join Me on Zerply" url="http://zerply.com">

object.title?
=> true
object.title
=> "Join Me on Zerply"

object.url?
=> true
object.url
=> "http://zerply.com"

object.foo?
=> false
object.foo
=> nil

Now with a regular website with no particular protocol:

object = LinkThumbnailer.generate('http://foo.com')
 => #<LinkThumbnailer::Object description=nil images=[[ JPEG 750x200 750x200+0+0 DirectClass 8-bit 45kb] scene=0] title="Foo.com" url="http://foo.com">

object.title
 => "Foo.com"

object.images
 => [[ JPEG 750x200 750x200+0+0 DirectClass 8-bit 45kb]
scene=0]

object.images.first.source_url
 => #<URI::HTTP:0x007ff7a923ef58 URL:http://foo.com/media/BAhbB1sHOgZmSSItMjAxMi8wNC8yNi8yMC8xMS80OS80MjYvY29yZG92YWJlYWNoLmpwZwY6BkVUWwg6BnA6CnRodW1iSSINNzUweDIwMCMGOwZU/cordovabeach.jpg>

object.to_hash
 => {"url"=>"http://foo.com", "images"=>[{:source_url=>"http://foo.com/media/BAhbB1sHOgZmSSItMjAxMi8wNC8yNi8yMC8xMS80OS80MjYvY29yZG92YWJlYWNoLmpwZwY6BkVUWwg6BnA6CnRodW1iSSINNzUweDIwMCMGOwZU/cordovabeach.jpg", :mime_type=>"image/jpeg", :rows=>200, :filesize=>46501, :number_colors=>9490}], "title"=>"Foo.com", "description"=>nil}

object.to_json
 => "{\"url\":\"http://foo.com\",\"images\":[{\"source_url\":\"http://foo.com/media/BAhbB1sHOgZmSSItMjAxMi8wNC8yNi8yMC8xMS80OS80MjYvY29yZG92YWJlYWNoLmpwZwY6BkVUWwg6BnA6CnRodW1iSSINNzUweDIwMCMGOwZU/cordovabeach.jpg\",\"mime_type\":\"image/jpeg\",\"rows\":200,\"filesize\":46501,\"number_colors\":9490}],\"title\":\"Foo.com\",\"description\":null}"

You can check whether this object is valid or not (set mandatory attributes in the initializer, defaults are [url, title, images])

object.valid?
=> true

You also can set options at runtime:

object = LinkThumbnailer.generate('http://foo.com', top: 10, limit: 20, redirect_limit: 5)

Preview Controller

For an easy integration into your application, use the builtin PreviewController.

Take a look at the demo application here.

Basically, all you have to do in your view is something like this:

<%= form_tag '/link/preview', method: :post, remote: true do %>
	<%= text_field_tag :url %>
	<%= submit_tag 'Preview' %>
<% end %>

Don't forget to add this anywhere in your routes.rb file:

use_link_thumbnailer

Note: You won't have to bother with this if you did run the installer using:

$ rails g link_thumbnailer:install

The PreviewController will automatically respond to json calls, returning json version of the preview object. Just like in the IRB console above.

Configuration

In config/initializers/link_thumbnailer.rb

LinkThumbnailer.configure do |config|
  # Set mandatory attributes require for the website to be valid.
  # You can set `strict` to false if you want to skip this validation.
  # config.mandatory_attributes = %w(url title image)

  # Whether you want to validate given website against mandatory attributes or not.
  # config.strict = true

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

  # 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/}
  # ]

  # Fetch 10 images maximum.
  # config.limit = 10

  # Return top 5 images only.
  # config.top = 5

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

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

  # HTTP open_timeout: The amount of time in seconds to wait for a connection to be opened.
  # config.http_timeout = 5
end

Features

Implemented:

Implements OpenGraph protocol.
Find images and sort them according to how well they represent what the page is about (includes absolute images).
Sort images based on their size and color.
Blacklist some well known advertisings image urls.
Routes and Controllers to handle preview generation

Coming soon:

Use the gem ruby-readability to parse images and website information
Cache results on filesystem

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

sharp / link_thumbnailer Goto Github PK