vendor/rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb

   1 require 'cgi'
   2 require 'action_view/helpers/url_helper'
   3 require 'action_view/helpers/tag_helper'
   4
   5 module ActionView
   6   module Helpers #:nodoc:
   7     # This module provides methods for generating HTML that links views to assets such
   8     # as images, javascripts, stylesheets, and feeds. These methods do not verify
   9     # the assets exist before linking to them:
  10     #
  11     #   image_tag("rails.png")
  12     #   # => <img alt="Rails src="/images/rails.png?1230601161" />
  13     #   stylesheet_link_tag("application")
  14     #   # => <link href="/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />
  15     #
  16     # === Using asset hosts
  17     #
  18     # By default, Rails links to these assets on the current host in the public
  19     # folder, but you can direct Rails to link to assets from a dedicated asset
  20     # server by setting ActionController::Base.asset_host in the application
  21     # configuration, typically in <tt>config/environments/production.rb</tt>.
  22     # For example, you'd define <tt>assets.example.com</tt> to be your asset
  23     # host this way:
  24     #
  25     #   ActionController::Base.asset_host = "assets.example.com"
  26     #
  27     # Helpers take that into account:
  28     #
  29     #   image_tag("rails.png")
  30     #   # => <img alt="Rails" src="http://assets.example.com/images/rails.png?1230601161" />
  31     #   stylesheet_link_tag("application")
  32     #   # => <link href="http://assets.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />
  33     #
  34     # Browsers typically open at most two simultaneous connections to a single
  35     # host, which means your assets often have to wait for other assets to finish
  36     # downloading. You can alleviate this by using a <tt>%d</tt> wildcard in the
  37     # +asset_host+. For example, "assets%d.example.com". If that wildcard is
  38     # present Rails distributes asset requests among the corresponding four hosts
  39     # "assets0.example.com", ..., "assets3.example.com". With this trick browsers
  40     # will open eight simultaneous connections rather than two.
  41     #
  42     #   image_tag("rails.png")
  43     #   # => <img alt="Rails" src="http://assets0.example.com/images/rails.png?1230601161" />
  44     #   stylesheet_link_tag("application")
  45     #   # => <link href="http://assets2.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />
  46     #
  47     # To do this, you can either setup four actual hosts, or you can use wildcard
  48     # DNS to CNAME the wildcard to a single asset host. You can read more about
  49     # setting up your DNS CNAME records from your ISP.
  50     #
  51     # Note: This is purely a browser performance optimization and is not meant
  52     # for server load balancing. See http://www.die.net/musings/page_load_time/
  53     # for background.
  54     #
  55     # Alternatively, you can exert more control over the asset host by setting
  56     # +asset_host+ to a proc like this:
  57     #
  58     #   ActionController::Base.asset_host = Proc.new { |source|
  59     #     "http://assets#{rand(2) + 1}.example.com"
  60     #   }
  61     #   image_tag("rails.png")
  62     #   # => <img alt="Rails" src="http://assets0.example.com/images/rails.png?1230601161" />
  63     #   stylesheet_link_tag("application")
  64     #   # => <link href="http://assets1.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />
  65     #
  66     # The example above generates "http://assets1.example.com" and
  67     # "http://assets2.example.com" randomly. This option is useful for example if
  68     # you need fewer/more than four hosts, custom host names, etc.
  69     #
  70     # As you see the proc takes a +source+ parameter. That's a string with the
  71     # absolute path of the asset with any extensions and timestamps in place,
  72     # for example "/images/rails.png?1230601161".
  73     #
  74     #    ActionController::Base.asset_host = Proc.new { |source|
  75     #      if source.starts_with?('/images')
  76     #        "http://images.example.com"
  77     #      else
  78     #        "http://assets.example.com"
  79     #      end
  80     #    }
  81     #   image_tag("rails.png")
  82     #   # => <img alt="Rails" src="http://images.example.com/images/rails.png?1230601161" />
  83     #   stylesheet_link_tag("application")
  84     #   # => <link href="http://assets.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />
  85     #
  86     # Alternatively you may ask for a second parameter +request+. That one is
  87     # particularly useful for serving assets from an SSL-protected page. The
  88     # example proc below disables asset hosting for HTTPS connections, while
  89     # still sending assets for plain HTTP requests from asset hosts. If you don't
  90     # have SSL certificates for each of the asset hosts this technique allows you
  91     # to avoid warnings in the client about mixed media.
  92     #
  93     #   ActionController::Base.asset_host = Proc.new { |source, request|
  94     #     if request.ssl?
  95     #       "#{request.protocol}#{request.host_with_port}"
  96     #     else
  97     #       "#{request.protocol}assets.example.com"
  98     #     end
  99     #   }
 100     #
 101     # You can also implement a custom asset host object that responds to +call+
 102     # and takes either one or two parameters just like the proc.
 103     #
 104     #   config.action_controller.asset_host = AssetHostingWithMinimumSsl.new(
 105     #     "http://asset%d.example.com", "https://asset1.example.com"
 106     #   )
 107     #
 108     # === Using asset timestamps
 109     #
 110     # By default, Rails appends asset's timestamps to all asset paths. This allows
 111     # you to set a cache-expiration date for the asset far into the future, but
 112     # still be able to instantly invalidate it by simply updating the file (and
 113     # hence updating the timestamp, which then updates the URL as the timestamp
 114     # is part of that, which in turn busts the cache).
 115     #
 116     # It's the responsibility of the web server you use to set the far-future
 117     # expiration date on cache assets that you need to take advantage of this
 118     # feature. Here's an example for Apache:
 119     #
 120     #   # Asset Expiration
 121     #   ExpiresActive On
 122     #   <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$">
 123     #     ExpiresDefault "access plus 1 year"
 124     #   </FilesMatch>
 125     #
 126     # Also note that in order for this to work, all your application servers must
 127     # return the same timestamps. This means that they must have their clocks
 128     # synchronized. If one of them drifts out of sync, you'll see different
 129     # timestamps at random and the cache won't work. In that case the browser
 130     # will request the same assets over and over again even thought they didn't
 131     # change. You can use something like Live HTTP Headers for Firefox to verify
 132     # that the cache is indeed working.
 133     module AssetTagHelper
 134       ASSETS_DIR      = defined?(Rails.public_path) ? Rails.public_path : "public"
 135       JAVASCRIPTS_DIR = "#{ASSETS_DIR}/javascripts"
 136       STYLESHEETS_DIR = "#{ASSETS_DIR}/stylesheets"
 137       JAVASCRIPT_DEFAULT_SOURCES = ['prototype', 'effects', 'dragdrop', 'controls'].freeze unless const_defined?(:JAVASCRIPT_DEFAULT_SOURCES)
 138
 139       # Returns a link tag that browsers and news readers can use to auto-detect
 140       # an RSS or ATOM feed. The +type+ can either be <tt>:rss</tt> (default) or
 141       # <tt>:atom</tt>. Control the link options in url_for format using the
 142       # +url_options+. You can modify the LINK tag itself in +tag_options+.
 143       #
 144       # ==== Options
 145       # * <tt>:rel</tt>  - Specify the relation of this link, defaults to "alternate"
 146       # * <tt>:type</tt>  - Override the auto-generated mime type
 147       # * <tt>:title</tt>  - Specify the title of the link, defaults to the +type+
 148       #
 149       # ==== Examples
 150       #  auto_discovery_link_tag # =>
 151       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/action" />
 152       #  auto_discovery_link_tag(:atom) # =>
 153       #     <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.currenthost.com/controller/action" />
 154       #  auto_discovery_link_tag(:rss, {:action => "feed"}) # =>
 155       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/feed" />
 156       #  auto_discovery_link_tag(:rss, {:action => "feed"}, {:title => "My RSS"}) # =>
 157       #     <link rel="alternate" type="application/rss+xml" title="My RSS" href="http://www.currenthost.com/controller/feed" />
 158       #  auto_discovery_link_tag(:rss, {:controller => "news", :action => "feed"}) # =>
 159       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/news/feed" />
 160       #  auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {:title => "Example RSS"}) # =>
 161       #     <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed" />
 162       def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
 163         tag(
 164           "link",
 165           "rel"   => tag_options[:rel] || "alternate",
 166           "type"  => tag_options[:type] || Mime::Type.lookup_by_extension(type.to_s).to_s,
 167           "title" => tag_options[:title] || type.to_s.upcase,
 168           "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(:only_path => false)) : url_options
 169         )
 170       end
 171
 172       # Computes the path to a javascript asset in the public javascripts directory.
 173       # If the +source+ filename has no extension, .js will be appended.
 174       # Full paths from the document root will be passed through.
 175       # Used internally by javascript_include_tag to build the script path.
 176       #
 177       # ==== Examples
 178       #   javascript_path "xmlhr" # => /javascripts/xmlhr.js
 179       #   javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
 180       #   javascript_path "/dir/xmlhr" # => /dir/xmlhr.js
 181       #   javascript_path "http://www.railsapplication.com/js/xmlhr" # => http://www.railsapplication.com/js/xmlhr.js
 182       #   javascript_path "http://www.railsapplication.com/js/xmlhr.js" # => http://www.railsapplication.com/js/xmlhr.js
 183       def javascript_path(source)
 184         compute_public_path(source, 'javascripts', 'js')
 185       end
 186       alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with a javascript_path named route
 187
 188       # Returns an html script tag for each of the +sources+ provided. You
 189       # can pass in the filename (.js extension is optional) of javascript files
 190       # that exist in your public/javascripts directory for inclusion into the
 191       # current page or you can pass the full path relative to your document
 192       # root. To include the Prototype and Scriptaculous javascript libraries in
 193       # your application, pass <tt>:defaults</tt> as the source. When using
 194       # <tt>:defaults</tt>, if an application.js file exists in your public
 195       # javascripts directory, it will be included as well. You can modify the
 196       # html attributes of the script tag by passing a hash as the last argument.
 197       #
 198       # ==== Examples
 199       #   javascript_include_tag "xmlhr" # =>
 200       #     <script type="text/javascript" src="/javascripts/xmlhr.js"></script>
 201       #
 202       #   javascript_include_tag "xmlhr.js" # =>
 203       #     <script type="text/javascript" src="/javascripts/xmlhr.js"></script>
 204       #
 205       #   javascript_include_tag "common.javascript", "/elsewhere/cools" # =>
 206       #     <script type="text/javascript" src="/javascripts/common.javascript"></script>
 207       #     <script type="text/javascript" src="/elsewhere/cools.js"></script>
 208       #
 209       #   javascript_include_tag "http://www.railsapplication.com/xmlhr" # =>
 210       #     <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>
 211       #
 212       #   javascript_include_tag "http://www.railsapplication.com/xmlhr.js" # =>
 213       #     <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>
 214       #
 215       #   javascript_include_tag :defaults # =>
 216       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 217       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 218       #     ...
 219       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 220       #
 221       # * = The application.js file is only referenced if it exists
 222       #
 223       # Though it's not really recommended practice, if you need to extend the default JavaScript set for any reason
 224       # (e.g., you're going to be using a certain .js file in every action), then take a look at the register_javascript_include_default method.
 225       #
 226       # You can also include all javascripts in the javascripts directory using <tt>:all</tt> as the source:
 227       #
 228       #   javascript_include_tag :all # =>
 229       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 230       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 231       #     ...
 232       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 233       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 234       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 235       #
 236       # Note that the default javascript files will be included first. So Prototype and Scriptaculous are available to
 237       # all subsequently included files.
 238       #
 239       # If you want Rails to search in all the subdirectories under javascripts, you should explicitly set <tt>:recursive</tt>:
 240       #
 241       #   javascript_include_tag :all, :recursive => true
 242       #
 243       # == Caching multiple javascripts into one
 244       #
 245       # You can also cache multiple javascripts into one file, which requires less HTTP connections to download and can better be
 246       # compressed by gzip (leading to faster transfers). Caching will only happen if ActionController::Base.perform_caching
 247       # is set to <tt>true</tt> (which is the case by default for the Rails production environment, but not for the development
 248       # environment).
 249       #
 250       # ==== Examples
 251       #   javascript_include_tag :all, :cache => true # when ActionController::Base.perform_caching is false =>
 252       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 253       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 254       #     ...
 255       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 256       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 257       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 258       #
 259       #   javascript_include_tag :all, :cache => true # when ActionController::Base.perform_caching is true =>
 260       #     <script type="text/javascript" src="/javascripts/all.js"></script>
 261       #
 262       #   javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when ActionController::Base.perform_caching is false =>
 263       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 264       #     <script type="text/javascript" src="/javascripts/cart.js"></script>
 265       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 266       #
 267       #   javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when ActionController::Base.perform_caching is true =>
 268       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 269       #
 270       # The <tt>:recursive</tt> option is also available for caching:
 271       #
 272       #   javascript_include_tag :all, :cache => true, :recursive => true
 273       def javascript_include_tag(*sources)
 274         options = sources.extract_options!.stringify_keys
 275         cache   = options.delete("cache")
 276         recursive = options.delete("recursive")
 277
 278         if ActionController::Base.perform_caching && cache
 279           joined_javascript_name = (cache == true ? "all" : cache) + ".js"
 280           joined_javascript_path = File.join(JAVASCRIPTS_DIR, joined_javascript_name)
 281
 282           write_asset_file_contents(joined_javascript_path, compute_javascript_paths(sources, recursive)) unless File.exists?(joined_javascript_path)
 283           javascript_src_tag(joined_javascript_name, options)
 284         else
 285           expand_javascript_sources(sources, recursive).collect { |source| javascript_src_tag(source, options) }.join("\n")
 286         end
 287       end
 288
 289       @@javascript_expansions = { :defaults => JAVASCRIPT_DEFAULT_SOURCES.dup }
 290
 291       # Register one or more javascript files to be included when <tt>symbol</tt>
 292       # is passed to <tt>javascript_include_tag</tt>. This method is typically intended
 293       # to be called from plugin initialization to register javascript files
 294       # that the plugin installed in <tt>public/javascripts</tt>.
 295       #
 296       #   ActionView::Helpers::AssetTagHelper.register_javascript_expansion :monkey => ["head", "body", "tail"]
 297       #
 298       #   javascript_include_tag :monkey # =>
 299       #     <script type="text/javascript" src="/javascripts/head.js"></script>
 300       #     <script type="text/javascript" src="/javascripts/body.js"></script>
 301       #     <script type="text/javascript" src="/javascripts/tail.js"></script>
 302       def self.register_javascript_expansion(expansions)
 303         @@javascript_expansions.merge!(expansions)
 304       end
 305
 306       @@stylesheet_expansions = {}
 307
 308       # Register one or more stylesheet files to be included when <tt>symbol</tt>
 309       # is passed to <tt>stylesheet_link_tag</tt>. This method is typically intended
 310       # to be called from plugin initialization to register stylesheet files
 311       # that the plugin installed in <tt>public/stylesheets</tt>.
 312       #
 313       #   ActionView::Helpers::AssetTagHelper.register_stylesheet_expansion :monkey => ["head", "body", "tail"]
 314       #
 315       #   stylesheet_link_tag :monkey # =>
 316       #     <link href="/stylesheets/head.css"  media="screen" rel="stylesheet" type="text/css" />
 317       #     <link href="/stylesheets/body.css"  media="screen" rel="stylesheet" type="text/css" />
 318       #     <link href="/stylesheets/tail.css"  media="screen" rel="stylesheet" type="text/css" />
 319       def self.register_stylesheet_expansion(expansions)
 320         @@stylesheet_expansions.merge!(expansions)
 321       end
 322
 323       # Register one or more additional JavaScript files to be included when
 324       # <tt>javascript_include_tag :defaults</tt> is called. This method is
 325       # typically intended to be called from plugin initialization to register additional
 326       # .js files that the plugin installed in <tt>public/javascripts</tt>.
 327       def self.register_javascript_include_default(*sources)
 328         @@javascript_expansions[:defaults].concat(sources)
 329       end
 330
 331       def self.reset_javascript_include_default #:nodoc:
 332         @@javascript_expansions[:defaults] = JAVASCRIPT_DEFAULT_SOURCES.dup
 333       end
 334
 335       # Computes the path to a stylesheet asset in the public stylesheets directory.
 336       # If the +source+ filename has no extension, <tt>.css</tt> will be appended.
 337       # Full paths from the document root will be passed through.
 338       # Used internally by +stylesheet_link_tag+ to build the stylesheet path.
 339       #
 340       # ==== Examples
 341       #   stylesheet_path "style" # => /stylesheets/style.css
 342       #   stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
 343       #   stylesheet_path "/dir/style.css" # => /dir/style.css
 344       #   stylesheet_path "http://www.railsapplication.com/css/style" # => http://www.railsapplication.com/css/style.css
 345       #   stylesheet_path "http://www.railsapplication.com/css/style.js" # => http://www.railsapplication.com/css/style.css
 346       def stylesheet_path(source)
 347         compute_public_path(source, 'stylesheets', 'css')
 348       end
 349       alias_method :path_to_stylesheet, :stylesheet_path # aliased to avoid conflicts with a stylesheet_path named route
 350
 351       # Returns a stylesheet link tag for the sources specified as arguments. If
 352       # you don't specify an extension, <tt>.css</tt> will be appended automatically.
 353       # You can modify the link attributes by passing a hash as the last argument.
 354       #
 355       # ==== Examples
 356       #   stylesheet_link_tag "style" # =>
 357       #     <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />
 358       #
 359       #   stylesheet_link_tag "style.css" # =>
 360       #     <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />
 361       #
 362       #   stylesheet_link_tag "http://www.railsapplication.com/style.css" # =>
 363       #     <link href="http://www.railsapplication.com/style.css" media="screen" rel="stylesheet" type="text/css" />
 364       #
 365       #   stylesheet_link_tag "style", :media => "all" # =>
 366       #     <link href="/stylesheets/style.css" media="all" rel="stylesheet" type="text/css" />
 367       #
 368       #   stylesheet_link_tag "style", :media => "print" # =>
 369       #     <link href="/stylesheets/style.css" media="print" rel="stylesheet" type="text/css" />
 370       #
 371       #   stylesheet_link_tag "random.styles", "/css/stylish" # =>
 372       #     <link href="/stylesheets/random.styles" media="screen" rel="stylesheet" type="text/css" />
 373       #     <link href="/css/stylish.css" media="screen" rel="stylesheet" type="text/css" />
 374       #
 375       # You can also include all styles in the stylesheets directory using <tt>:all</tt> as the source:
 376       #
 377       #   stylesheet_link_tag :all # =>
 378       #     <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
 379       #     <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
 380       #     <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />
 381       #
 382       # If you want Rails to search in all the subdirectories under stylesheets, you should explicitly set <tt>:recursive</tt>:
 383       #
 384       #   stylesheet_link_tag :all, :recursive => true
 385       #
 386       # == Caching multiple stylesheets into one
 387       #
 388       # You can also cache multiple stylesheets into one file, which requires less HTTP connections and can better be
 389       # compressed by gzip (leading to faster transfers). Caching will only happen if ActionController::Base.perform_caching
 390       # is set to true (which is the case by default for the Rails production environment, but not for the development
 391       # environment). Examples:
 392       #
 393       # ==== Examples
 394       #   stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is false =>
 395       #     <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
 396       #     <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
 397       #     <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />
 398       #
 399       #   stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is true =>
 400       #     <link href="/stylesheets/all.css"  media="screen" rel="stylesheet" type="text/css" />
 401       #
 402       #   stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when ActionController::Base.perform_caching is false =>
 403       #     <link href="/stylesheets/shop.css"  media="screen" rel="stylesheet" type="text/css" />
 404       #     <link href="/stylesheets/cart.css"  media="screen" rel="stylesheet" type="text/css" />
 405       #     <link href="/stylesheets/checkout.css" media="screen" rel="stylesheet" type="text/css" />
 406       #
 407       #   stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when ActionController::Base.perform_caching is true =>
 408       #     <link href="/stylesheets/payment.css"  media="screen" rel="stylesheet" type="text/css" />
 409       #
 410       # The <tt>:recursive</tt> option is also available for caching:
 411       #
 412       #   stylesheet_link_tag :all, :cache => true, :recursive => true
 413       def stylesheet_link_tag(*sources)
 414         options = sources.extract_options!.stringify_keys
 415         cache   = options.delete("cache")
 416         recursive = options.delete("recursive")
 417
 418         if ActionController::Base.perform_caching && cache
 419           joined_stylesheet_name = (cache == true ? "all" : cache) + ".css"
 420           joined_stylesheet_path = File.join(STYLESHEETS_DIR, joined_stylesheet_name)
 421
 422           write_asset_file_contents(joined_stylesheet_path, compute_stylesheet_paths(sources, recursive)) unless File.exists?(joined_stylesheet_path)
 423           stylesheet_tag(joined_stylesheet_name, options)
 424         else
 425           expand_stylesheet_sources(sources, recursive).collect { |source| stylesheet_tag(source, options) }.join("\n")
 426         end
 427       end
 428
 429       # Computes the path to an image asset in the public images directory.
 430       # Full paths from the document root will be passed through.
 431       # Used internally by +image_tag+ to build the image path.
 432       #
 433       # ==== Examples
 434       #   image_path("edit")                                         # => /images/edit
 435       #   image_path("edit.png")                                     # => /images/edit.png
 436       #   image_path("icons/edit.png")                               # => /images/icons/edit.png
 437       #   image_path("/icons/edit.png")                              # => /icons/edit.png
 438       #   image_path("http://www.railsapplication.com/img/edit.png") # => http://www.railsapplication.com/img/edit.png
 439       def image_path(source)
 440         compute_public_path(source, 'images')
 441       end
 442       alias_method :path_to_image, :image_path # aliased to avoid conflicts with an image_path named route
 443
 444       # Returns an html image tag for the +source+. The +source+ can be a full
 445       # path or a file that exists in your public images directory.
 446       #
 447       # ==== Options
 448       # You can add HTML attributes using the +options+. The +options+ supports
 449       # three additional keys for convenience and conformance:
 450       #
 451       # * <tt>:alt</tt>  - If no alt text is given, the file name part of the
 452       #   +source+ is used (capitalized and without the extension)
 453       # * <tt>:size</tt> - Supplied as "{Width}x{Height}", so "30x45" becomes
 454       #   width="30" and height="45". <tt>:size</tt> will be ignored if the
 455       #   value is not in the correct format.
 456       # * <tt>:mouseover</tt> - Set an alternate image to be used when the onmouseover
 457       #   event is fired, and sets the original image to be replaced onmouseout.
 458       #   This can be used to implement an easy image toggle that fires on onmouseover.
 459       #
 460       # ==== Examples
 461       #  image_tag("icon")  # =>
 462       #    <img src="/images/icon" alt="Icon" />
 463       #  image_tag("icon.png")  # =>
 464       #    <img src="/images/icon.png" alt="Icon" />
 465       #  image_tag("icon.png", :size => "16x10", :alt => "Edit Entry")  # =>
 466       #    <img src="/images/icon.png" width="16" height="10" alt="Edit Entry" />
 467       #  image_tag("/icons/icon.gif", :size => "16x16")  # =>
 468       #    <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />
 469       #  image_tag("/icons/icon.gif", :height => '32', :width => '32') # =>
 470       #    <img alt="Icon" height="32" src="/icons/icon.gif" width="32" />
 471       #  image_tag("/icons/icon.gif", :class => "menu_icon") # =>
 472       #    <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
 473       #  image_tag("mouse.png", :mouseover => "/images/mouse_over.png") # =>
 474       #    <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
 475       #  image_tag("mouse.png", :mouseover => image_path("mouse_over.png")) # =>
 476       #    <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
 477       def image_tag(source, options = {})
 478         options.symbolize_keys!
 479
 480         options[:src] = path_to_image(source)
 481         options[:alt] ||= File.basename(options[:src], '.*').split('.').first.to_s.capitalize
 482
 483         if size = options.delete(:size)
 484           options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
 485         end
 486
 487         if mouseover = options.delete(:mouseover)
 488           options[:onmouseover] = "this.src='#{image_path(mouseover)}'"
 489           options[:onmouseout]  = "this.src='#{image_path(options[:src])}'"
 490         end
 491
 492         tag("img", options)
 493       end
 494
 495       def self.cache_asset_timestamps
 496         @@cache_asset_timestamps
 497       end
 498
 499       # You can enable or disable the asset tag timestamps cache.
 500       # With the cache enabled, the asset tag helper methods will make fewer
 501       # expense file system calls. However this prevents you from modifying
 502       # any asset files while the server is running.
 503       #
 504       #   ActionView::Helpers::AssetTagHelper.cache_asset_timestamps = false
 505       def self.cache_asset_timestamps=(value)
 506         @@cache_asset_timestamps = value
 507       end
 508
 509       @@cache_asset_timestamps = true
 510
 511       private
 512         # Add the the extension +ext+ if not present. Return full URLs otherwise untouched.
 513         # Prefix with <tt>/dir/</tt> if lacking a leading +/+. Account for relative URL
 514         # roots. Rewrite the asset path for cache-busting asset ids. Include
 515         # asset host, if configured, with the correct request protocol.
 516         def compute_public_path(source, dir, ext = nil, include_host = true)
 517           has_request = @controller.respond_to?(:request)
 518
 519           source_ext = File.extname(source)[1..-1]
 520           if ext && (source_ext.blank? || (ext != source_ext && File.exist?(File.join(ASSETS_DIR, dir, "#{source}.#{ext}"))))
 521             source += ".#{ext}"
 522           end
 523
 524           unless source =~ %r{^[-a-z]+://}
 525             source = "/#{dir}/#{source}" unless source[0] == ?/
 526
 527             source = rewrite_asset_path(source)
 528
 529             if has_request && include_host
 530               unless source =~ %r{^#{ActionController::Base.relative_url_root}/}
 531                 source = "#{ActionController::Base.relative_url_root}#{source}"
 532               end
 533             end
 534           end
 535
 536           if include_host && source !~ %r{^[-a-z]+://}
 537             host = compute_asset_host(source)
 538
 539             if has_request && !host.blank? && host !~ %r{^[-a-z]+://}
 540               host = "#{@controller.request.protocol}#{host}"
 541             end
 542
 543             "#{host}#{source}"
 544           else
 545             source
 546           end
 547         end
 548
 549         # Pick an asset host for this source. Returns +nil+ if no host is set,
 550         # the host if no wildcard is set, the host interpolated with the
 551         # numbers 0-3 if it contains <tt>%d</tt> (the number is the source hash mod 4),
 552         # or the value returned from invoking the proc if it's a proc or the value from
 553         # invoking call if it's an object responding to call.
 554         def compute_asset_host(source)
 555           if host = ActionController::Base.asset_host
 556             if host.is_a?(Proc) || host.respond_to?(:call)
 557               case host.is_a?(Proc) ? host.arity : host.method(:call).arity
 558               when 2
 559                 request = @controller.respond_to?(:request) && @controller.request
 560                 host.call(source, request)
 561               else
 562                 host.call(source)
 563               end
 564             else
 565               (host =~ /%d/) ? host % (source.hash % 4) : host
 566             end
 567           end
 568         end
 569
 570         @@asset_timestamps_cache = {}
 571         @@asset_timestamps_cache_guard = Mutex.new
 572
 573         # Use the RAILS_ASSET_ID environment variable or the source's
 574         # modification time as its cache-busting asset id.
 575         def rails_asset_id(source)
 576           if asset_id = ENV["RAILS_ASSET_ID"]
 577             asset_id
 578           else
 579             if @@cache_asset_timestamps && (asset_id = @@asset_timestamps_cache[source])
 580               asset_id
 581             else
 582               path = File.join(ASSETS_DIR, source)
 583               asset_id = File.exist?(path) ? File.mtime(path).to_i.to_s : ''
 584
 585               if @@cache_asset_timestamps
 586                 @@asset_timestamps_cache_guard.synchronize do
 587                   @@asset_timestamps_cache[source] = asset_id
 588                 end
 589               end
 590
 591               asset_id
 592             end
 593           end
 594         end
 595
 596         # Break out the asset path rewrite in case plugins wish to put the asset id
 597         # someplace other than the query string.
 598         def rewrite_asset_path(source)
 599           asset_id = rails_asset_id(source)
 600           if asset_id.blank?
 601             source
 602           else
 603             source + "?#{asset_id}"
 604           end
 605         end
 606
 607         def javascript_src_tag(source, options)
 608           content_tag("script", "", { "type" => Mime::JS, "src" => path_to_javascript(source) }.merge(options))
 609         end
 610
 611         def stylesheet_tag(source, options)
 612           tag("link", { "rel" => "stylesheet", "type" => Mime::CSS, "media" => "screen", "href" => html_escape(path_to_stylesheet(source)) }.merge(options), false, false)
 613         end
 614
 615         def compute_javascript_paths(*args)
 616           expand_javascript_sources(*args).collect { |source| compute_public_path(source, 'javascripts', 'js', false) }
 617         end
 618
 619         def compute_stylesheet_paths(*args)
 620           expand_stylesheet_sources(*args).collect { |source| compute_public_path(source, 'stylesheets', 'css', false) }
 621         end
 622
 623         def expand_javascript_sources(sources, recursive = false)
 624           if sources.include?(:all)
 625             all_javascript_files = collect_asset_files(JAVASCRIPTS_DIR, ('**' if recursive), '*.js')
 626             ((determine_source(:defaults, @@javascript_expansions).dup & all_javascript_files) + all_javascript_files).uniq
 627           else
 628             expanded_sources = sources.collect do |source|
 629               determine_source(source, @@javascript_expansions)
 630             end.flatten
 631             expanded_sources << "application" if sources.include?(:defaults) && File.exist?(File.join(JAVASCRIPTS_DIR, "application.js"))
 632             expanded_sources
 633           end
 634         end
 635
 636         def expand_stylesheet_sources(sources, recursive)
 637           if sources.first == :all
 638             collect_asset_files(STYLESHEETS_DIR, ('**' if recursive), '*.css')
 639           else
 640             sources.collect do |source|
 641               determine_source(source, @@stylesheet_expansions)
 642             end.flatten
 643           end
 644         end
 645
 646         def determine_source(source, collection)
 647           case source
 648           when Symbol
 649             collection[source] || raise(ArgumentError, "No expansion found for #{source.inspect}")
 650           else
 651             source
 652           end
 653         end
 654
 655         def join_asset_file_contents(paths)
 656           paths.collect { |path| File.read(asset_file_path(path)) }.join("\n\n")
 657         end
 658
 659         def write_asset_file_contents(joined_asset_path, asset_paths)
 660           FileUtils.mkdir_p(File.dirname(joined_asset_path))
 661           File.open(joined_asset_path, "w+") { |cache| cache.write(join_asset_file_contents(asset_paths)) }
 662
 663           # Set mtime to the latest of the combined files to allow for
 664           # consistent ETag without a shared filesystem.
 665           mt = asset_paths.map { |p| File.mtime(asset_file_path(p)) }.max
 666           File.utime(mt, mt, joined_asset_path)
 667         end
 668
 669         def asset_file_path(path)
 670           File.join(ASSETS_DIR, path.split('?').first)
 671         end
 672
 673         def collect_asset_files(*path)
 674           dir = path.first
 675
 676           Dir[File.join(*path.compact)].collect do |file|
 677             file[-(file.size - dir.size - 1)..-1].sub(/\.\w+$/, '')
 678           end.sort
 679         end
 680     end
 681   end
 682 end