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Rails plugin: treat your Adobe Flash swf files like any other asset (images, javascripts, etc...) and embed them using SWFObject 2.2
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swf_fu Gem Version Click here to lend your support to: swf_fu and make a donation at !

With the swf_fu plugin, rails treats your swf files like any other asset (images, javascripts, etc…).

swf_fu (pronounced “swif-fu”, bonus joke for french speakers) uses SWFObject 2.2 to embed swf objects in HTML and supports all its options. SWFObject 2 is such a nice library that Adobe now uses it as the official way to embed swf! SWFObject's project can be found at

Comments and pull requests welcome:


Version 2 of swf_fu is an engine for Rails 3.1+ and Ruby 1.8.7+.

Version 1.x was a plugin for previous versions of Rails and should not be used with Rails 3.1+. If you want to use it, checkout the v1.x branch. If you are upgrading to Rails 3.1+, remove the plugin!


Add to your Gemfile:

gem "swf_fu", "~> 2.0"

Then run `bundle install`.

You also need to require some javascripts, so in your `app/assets/javascripts/application.js` you want to append:

\\= require swf_fu


Embedding in HTML

To embed a swf file, use swf_tag:

<%= swf_tag "i_like_flashing" %>

Exactly like images and javascripts, swf_tag will use swf_path to determine the path of the swf file; it will assume it is in /assets/swfs/ or in /public/swfs/ unless specified otherwise and it will add the “.swf” extension automatically.

You can specify alternate content either with the options :alt => "Get Flash!" or you can use swf_tag as a block:

<% swf_tag "i_like_flashing" do %>
  Get Flash
<% end %>


  • :id - the DOM id of the flash object element that is used to contain the Flash object; defaults to the name of the swf in source

  • :width, :height - the width & height of the Flash object. Defaults to “100%”. These could also specified using :size

  • :size - the size of the Flash object, in the form “400x300”.

  • :mode - Either :dynamic (default) or :static. Refer to SWFObject's doc

  • :flashvars - a Hash of variables that are passed to the swf. Can also be a string like "foo=bar&hello=world". Defaults to {:id => the DOM id}

  • :parameters - a Hash of configuration parameters for the swf. See Adobe's doc

  • :html_options - a Hash of extra html options for the object tag.

  • :alt - HTML text that is displayed when the Flash player is not available. Defaults to a “Get Flash” image pointing to Adobe Flash's installation page. This can also be specified as a block (see embedding section). In Rails 3, this text is assumed to be HTML, so there is no need to call html_safe on it.

  • :flash_version - the version of the Flash player that is required (e.g. “7” (default) or “8.1.0”)

  • :auto_install - a swf file that will upgrade flash player if needed (defaults to “expressInstall” which was installed by swf_fu)

  • :javascript_class - specify a javascript class (e.g. “MyFlash”) for your flash object. If it exists, the initialize method will be called. See the 'dummy' example in the test folder

  • :initialize - arguments to pass to the initialization method of your javascript class.

  • :div_id - the DOM id of the containing div itself. Defaults to "#{option[:id]}_div"

  • :switch_off_auto_hide_show - switch off SWFObject's default hide/show behavior. SWFObject temporarily hides your SWF or alternative content until the library has decided which content to display. Defaults to nil.

You can override these default options with a global setting:

ActionView::Base.swf_default_options = {:mode => :static}   # All swf_tag will use the static mode by default

In your config files, you can write this as:

config.action_view.swf_default_options = {:mode => :static}   # All swf_tag will use the static mode by default

Any of these options can be a Proc, in which case it will be called each time swf_tag is called.

For example, the following will generate unique IDs:

my_swf_counter = 0
config.action_view.swf_default_options[:id] ={"swf_unique_id_#{my_swf_counter+=1}"}


swf_tag implements and relies on swf_path which behaves in a similar fashion to image_path, javascript_path, etc…:

swf_path("example")                            => "/swfs/example.swf" or "/assets/example.swf"
swf_path("example.swf")                        => "/swfs/example.swf" or "/assets/example.swf"
swf_path("fonts/optima")                       => "/swfs/fonts/optima.swf" or "/assets/fonts/optima.swf"
swf_path("/fonts/optima")                      => "/fonts/optima.swf"
swf_path("")    => ""

It takes into account the global setting asset_host, like any other asset:

ActionController::Base.asset_host = ""
image_path("logo.jpg")                         => ""
swf_path("fonts/optima")                       => ""

Copyright © 2010-2013 Marc-André Lafortune, released under the BSD license

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