Dragonfly

Dragonfly is a Rack framework for on-the-fly image handling.

Ideal for using with Ruby on Rails (2.3 and 3), Sinatra and all that gubbins.

For the lazy Rails user...

Gemfile:

gem 'rack-cache', :require => 'rack/cache'
gem 'dragonfly', '~>0.8.2'

Initializer (e.g. config/initializers/dragonfly.rb):

require 'dragonfly/rails/images'

Migration:

add_column :albums, :cover_image_uid, :string

Model:

class Album < ActiveRecord::Base
  image_accessor :cover_image            # 'image_accessor' is provided by Dragonfly
                                         # this defines a reader/writer for cover_image
  # ...
end

View (for uploading via a file field):

<% form_for @album, :html => {:multipart => true} do |f| %>
  ...
  <%= f.file_field :cover_image %>
  ...
<% end %>

NB: REMEMBER THE MULTIPART BIT!!!

View (to display):

<%= image_tag @album.cover_image.url %>
<%= image_tag @album.cover_image.thumb('400x200#').url %>
<%= image_tag @album.cover_image.jpg.url %>
<%= image_tag @album.cover_image.process(:greyscale).encode(:tiff).url %>
...etc.

The above relies on imagemagick being installed. Dragonfly doesn't depend on it per se, but the default configuration 'dragonfly/rails/images' uses it. For alternative configurations, see below.

If using Capistrano with the above, you probably will want to keep the cache between deploys, so in deploy.rb:

namespace :dragonfly do
  desc "Symlink the Rack::Cache files"
  task :symlink, :roles => [:app] do
    run "mkdir -p #{shared_path}/tmp/dragonfly && ln -nfs #{shared_path}/tmp/dragonfly #{release_path}/tmp/dragonfly"
  end
end
after 'deploy:update_code', 'dragonfly:symlink'

Using outside of rails, custom storage/processing/encoding/analysis, and more...

Dragonfly is primarily a Rack app, so you can use it as a standalone app, or with Sinatra, Merb, etc.

It's highly customizable, and works with any data type (not just images).

For more info, consult the DOCUMENTATION

Add-ons

For third-party add-ons, see the Add-ons wiki

Issues

Please use the github issue tracker if you have any issues.

Suggestions/Questions

Google group dragonfly-users

Credits

Mark Evans (author)