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.
However, Dragonfly is NOT JUST FOR RAILS, and NOT JUST FOR IMAGES!!
Gemfile:
gem 'rack-cache', :require => 'rack/cache'
gem 'dragonfly', '~>0.9.0'
Initializer (e.g. config/initializers/dragonfly.rb):
require 'dragonfly/rails/images'
Migration:
add_column :albums, :cover_image_uid, :string
add_column :albums, :cover_image_name, :string # Optional - only if you want urls
# to end with the original filename
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!!!
You can avoid having to re-upload when validations fail with
<%= f.hidden_field :retained_cover_image %>
remove the attachment with
<%= f.check_box :remove_cover_image %>
assign from some other url with
<%= f.text_field :cover_image_url %>
and display a thumbnail (on the upload form) with
<%= image_tag @album.cover_image.thumb('100x100').url if @album.cover_image_uid %>
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'
Dragonfly is not just for Rails - it's 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
For third-party add-ons, see the Add-ons wiki
Please use the github issue tracker if you have any issues.
- Mark Evans (author)
Copyright (c) 2009-2010 Mark Evans. See LICENSE for details.