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     # === Using asset hosts
  12     # By default, Rails links to these assets on the current host in the public
  13     # folder, but you can direct Rails to link to assets from a dedicated assets server by
  14     # setting ActionController::Base.asset_host in your <tt>config/environment.rb</tt>.  For example,
  15     # let's say your asset host is <tt>assets.example.com</tt>.
  16     #
  17     #   ActionController::Base.asset_host = "assets.example.com"
  18     #   image_tag("rails.png")
  19     #     => <img src="http://assets.example.com/images/rails.png" alt="Rails" />
  20     #   stylesheet_link_tag("application")
  21     #     => <link href="http://assets.example.com/stylesheets/application.css" media="screen" rel="stylesheet" type="text/css" />
  22     #
  23     # This is useful since browsers typically open at most two connections to a single host,
  24     # which means your assets often wait in single file for their turn to load.  You can
  25     # alleviate this by using a <tt>%d</tt> wildcard in <tt>asset_host</tt> (for example, "assets%d.example.com")
  26     # to automatically distribute asset requests among four hosts (e.g., "assets0.example.com" through "assets3.example.com")
  27     # so browsers will open eight connections rather than two.
  28     #
  29     #   image_tag("rails.png")
  30     #     => <img src="http://assets0.example.com/images/rails.png" alt="Rails" />
  31     #   stylesheet_link_tag("application")
  32     #     => <link href="http://assets3.example.com/stylesheets/application.css" media="screen" rel="stylesheet" type="text/css" />
  33     #
  34     # To do this, you can either setup 4 actual hosts, or you can use wildcard DNS to CNAME
  35     # the wildcard to a single asset host.  You can read more about setting up your DNS CNAME records from
  36     # your ISP.
  37     #
  38     # Note: This is purely a browser performance optimization and is not meant
  39     # for server load balancing. See http://www.die.net/musings/page_load_time/
  40     # for background.
  41     #
  42     # Alternatively, you can exert more control over the asset host by setting <tt>asset_host</tt> to a proc
  43     # that takes a single source argument. This is useful if you are unable to setup 4 actual hosts or have
  44     # fewer/more than 4 hosts. The example proc below generates http://assets1.example.com and
  45     # http://assets2.example.com randomly.
  46     #
  47     #   ActionController::Base.asset_host = Proc.new { |source| "http://assets#{rand(2) + 1}.example.com" }
  48     #   image_tag("rails.png")
  49     #     => <img src="http://assets2.example.com/images/rails.png" alt="Rails" />
  50     #   stylesheet_link_tag("application")
  51     #     => <link href="http://assets1.example.com/stylesheets/application.css" media="screen" rel="stylesheet" type="text/css" />
  52     #
  53     # The proc takes a <tt>source</tt> parameter (which is the path of the source asset) and an optional
  54     # <tt>request</tt> parameter (which is an entire instance of an <tt>ActionController::AbstractRequest</tt>
  55     # subclass). This can be used to generate a particular asset host depending on the asset path and the particular
  56     # request.
  57     #
  58     #    ActionController::Base.asset_host = Proc.new { |source|
  59     #      if source.starts_with?('/images')
  60     #        "http://images.example.com"
  61     #      else
  62     #        "http://assets.example.com"
  63     #      end
  64     #    }
  65     #   image_tag("rails.png")
  66     #     => <img src="http://images.example.com/images/rails.png" alt="Rails" />
  67     #   stylesheet_link_tag("application")
  68     #     => <link href="http://assets.example.com/stylesheets/application.css" media="screen" rel="stylesheet" type="text/css" />
  69     #
  70     # The optional <tt>request</tt> parameter to the proc is useful in particular for serving assets from an
  71     # SSL-protected page. The example proc below disables asset hosting for HTTPS connections, while still sending
  72     # assets for plain HTTP requests from asset hosts. This is useful for avoiding mixed media warnings when serving
  73     # non-HTTP assets from HTTPS web pages when you don't have an SSL certificate for each of the asset hosts.
  74     #
  75     #   ActionController::Base.asset_host = Proc.new { |source, request|
  76     #     if request.ssl?
  77     #       "#{request.protocol}#{request.host_with_port}"
  78     #     else
  79     #       "#{request.protocol}assets.example.com"
  80     #     end
  81     #   }
  82     #
  83     # === Using asset timestamps
  84     #
  85     # By default, Rails will append all asset paths with that asset's timestamp. This allows you to set a cache-expiration date for the
  86     # asset far into the future, but still be able to instantly invalidate it by simply updating the file (and hence updating the timestamp,
  87     # which then updates the URL as the timestamp is part of that, which in turn busts the cache).
  88     #
  89     # It's the responsibility of the web server you use to set the far-future expiration date on cache assets that you need to take
  90     # advantage of this feature. Here's an example for Apache:
  91     #
  92     # # Asset Expiration
  93     # ExpiresActive On
  94     # <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$">
  95     #   ExpiresDefault "access plus 1 year"
  96     # </FilesMatch>
  97     #
  98     # Also note that in order for this to work, all your application servers must return the same timestamps. This means that they must
  99     # have their clocks synchronized. If one of them drift out of sync, you'll see different timestamps at random and the cache won't
 100     # work. Which means that the browser will request the same assets over and over again even thought they didn't change. You can use
 101     # something like Live HTTP Headers for Firefox to verify that the cache is indeed working (and that the assets are not being
 102     # requested over and over).
 103     module AssetTagHelper
 104       ASSETS_DIR      = defined?(Rails.public_path) ? Rails.public_path : "public"
 105       JAVASCRIPTS_DIR = "#{ASSETS_DIR}/javascripts"
 106       STYLESHEETS_DIR = "#{ASSETS_DIR}/stylesheets"
 107       JAVASCRIPT_DEFAULT_SOURCES = ['prototype', 'effects', 'dragdrop', 'controls'].freeze unless const_defined?(:JAVASCRIPT_DEFAULT_SOURCES)
 108
 109       # Returns a link tag that browsers and news readers can use to auto-detect
 110       # an RSS or ATOM feed. The +type+ can either be <tt>:rss</tt> (default) or
 111       # <tt>:atom</tt>. Control the link options in url_for format using the
 112       # +url_options+. You can modify the LINK tag itself in +tag_options+.
 113       #
 114       # ==== Options:
 115       # * <tt>:rel</tt>  - Specify the relation of this link, defaults to "alternate"
 116       # * <tt>:type</tt>  - Override the auto-generated mime type
 117       # * <tt>:title</tt>  - Specify the title of the link, defaults to the +type+
 118       #
 119       # ==== Examples
 120       #  auto_discovery_link_tag # =>
 121       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/action" />
 122       #  auto_discovery_link_tag(:atom) # =>
 123       #     <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.currenthost.com/controller/action" />
 124       #  auto_discovery_link_tag(:rss, {:action => "feed"}) # =>
 125       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/feed" />
 126       #  auto_discovery_link_tag(:rss, {:action => "feed"}, {:title => "My RSS"}) # =>
 127       #     <link rel="alternate" type="application/rss+xml" title="My RSS" href="http://www.currenthost.com/controller/feed" />
 128       #  auto_discovery_link_tag(:rss, {:controller => "news", :action => "feed"}) # =>
 129       #     <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/news/feed" />
 130       #  auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {:title => "Example RSS"}) # =>
 131       #     <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed" />
 132       def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
 133         tag(
 134           "link",
 135           "rel"   => tag_options[:rel] || "alternate",
 136           "type"  => tag_options[:type] || Mime::Type.lookup_by_extension(type.to_s).to_s,
 137           "title" => tag_options[:title] || type.to_s.upcase,
 138           "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(:only_path => false)) : url_options
 139         )
 140       end
 141
 142       # Computes the path to a javascript asset in the public javascripts directory.
 143       # If the +source+ filename has no extension, .js will be appended.
 144       # Full paths from the document root will be passed through.
 145       # Used internally by javascript_include_tag to build the script path.
 146       #
 147       # ==== Examples
 148       #   javascript_path "xmlhr" # => /javascripts/xmlhr.js
 149       #   javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
 150       #   javascript_path "/dir/xmlhr" # => /dir/xmlhr.js
 151       #   javascript_path "http://www.railsapplication.com/js/xmlhr" # => http://www.railsapplication.com/js/xmlhr.js
 152       #   javascript_path "http://www.railsapplication.com/js/xmlhr.js" # => http://www.railsapplication.com/js/xmlhr.js
 153       def javascript_path(source)
 154         JavaScriptTag.new(self, @controller, source).public_path
 155       end
 156       alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with a javascript_path named route
 157
 158       # Returns an html script tag for each of the +sources+ provided. You
 159       # can pass in the filename (.js extension is optional) of javascript files
 160       # that exist in your public/javascripts directory for inclusion into the
 161       # current page or you can pass the full path relative to your document
 162       # root. To include the Prototype and Scriptaculous javascript libraries in
 163       # your application, pass <tt>:defaults</tt> as the source. When using
 164       # <tt>:defaults</tt>, if an application.js file exists in your public
 165       # javascripts directory, it will be included as well. You can modify the
 166       # html attributes of the script tag by passing a hash as the last argument.
 167       #
 168       # ==== Examples
 169       #   javascript_include_tag "xmlhr" # =>
 170       #     <script type="text/javascript" src="/javascripts/xmlhr.js"></script>
 171       #
 172       #   javascript_include_tag "xmlhr.js" # =>
 173       #     <script type="text/javascript" src="/javascripts/xmlhr.js"></script>
 174       #
 175       #   javascript_include_tag "common.javascript", "/elsewhere/cools" # =>
 176       #     <script type="text/javascript" src="/javascripts/common.javascript"></script>
 177       #     <script type="text/javascript" src="/elsewhere/cools.js"></script>
 178       #
 179       #   javascript_include_tag "http://www.railsapplication.com/xmlhr" # =>
 180       #     <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>
 181       #
 182       #   javascript_include_tag "http://www.railsapplication.com/xmlhr.js" # =>
 183       #     <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>
 184       #
 185       #   javascript_include_tag :defaults # =>
 186       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 187       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 188       #     ...
 189       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 190       #
 191       # * = The application.js file is only referenced if it exists
 192       #
 193       # Though it's not really recommended practice, if you need to extend the default JavaScript set for any reason
 194       # (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.
 195       #
 196       # You can also include all javascripts in the javascripts directory using <tt>:all</tt> as the source:
 197       #
 198       #   javascript_include_tag :all # =>
 199       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 200       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 201       #     ...
 202       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 203       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 204       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 205       #
 206       # Note that the default javascript files will be included first. So Prototype and Scriptaculous are available to
 207       # all subsequently included files.
 208       #
 209       # If you want Rails to search in all the subdirectories under javascripts, you should explicitly set <tt>:recursive</tt>:
 210       #
 211       #   javascript_include_tag :all, :recursive => true
 212       #
 213       # == Caching multiple javascripts into one
 214       #
 215       # You can also cache multiple javascripts into one file, which requires less HTTP connections to download and can better be
 216       # compressed by gzip (leading to faster transfers). Caching will only happen if ActionController::Base.perform_caching
 217       # is set to <tt>true</tt> (which is the case by default for the Rails production environment, but not for the development
 218       # environment).
 219       #
 220       # ==== Examples
 221       #   javascript_include_tag :all, :cache => true # when ActionController::Base.perform_caching is false =>
 222       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 223       #     <script type="text/javascript" src="/javascripts/effects.js"></script>
 224       #     ...
 225       #     <script type="text/javascript" src="/javascripts/application.js"></script>
 226       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 227       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 228       #
 229       #   javascript_include_tag :all, :cache => true # when ActionController::Base.perform_caching is true =>
 230       #     <script type="text/javascript" src="/javascripts/all.js"></script>
 231       #
 232       #   javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when ActionController::Base.perform_caching is false =>
 233       #     <script type="text/javascript" src="/javascripts/prototype.js"></script>
 234       #     <script type="text/javascript" src="/javascripts/cart.js"></script>
 235       #     <script type="text/javascript" src="/javascripts/checkout.js"></script>
 236       #
 237       #   javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when ActionController::Base.perform_caching is true =>
 238       #     <script type="text/javascript" src="/javascripts/shop.js"></script>
 239       #
 240       # The <tt>:recursive</tt> option is also available for caching:
 241       #
 242       #   javascript_include_tag :all, :cache => true, :recursive => true
 243       def javascript_include_tag(*sources)
 244         options = sources.extract_options!.stringify_keys
 245         cache   = options.delete("cache")
 246         recursive = options.delete("recursive")
 247
 248         if ActionController::Base.perform_caching && cache
 249           joined_javascript_name = (cache == true ? "all" : cache) + ".js"
 250           joined_javascript_path = File.join(JAVASCRIPTS_DIR, joined_javascript_name)
 251
 252           unless File.exists?(joined_javascript_path)
 253             JavaScriptSources.create(self, @controller, sources, recursive).write_asset_file_contents(joined_javascript_path)
 254           end
 255           javascript_src_tag(joined_javascript_name, options)
 256         else
 257           JavaScriptSources.create(self, @controller, sources, recursive).expand_sources.collect { |source|
 258             javascript_src_tag(source, options)
 259           }.join("\n")
 260         end
 261       end
 262
 263       # Register one or more javascript files to be included when <tt>symbol</tt>
 264       # is passed to <tt>javascript_include_tag</tt>. This method is typically intended
 265       # to be called from plugin initialization to register javascript files
 266       # that the plugin installed in <tt>public/javascripts</tt>.
 267       #
 268       #   ActionView::Helpers::AssetTagHelper.register_javascript_expansion :monkey => ["head", "body", "tail"]
 269       #
 270       #   javascript_include_tag :monkey # =>
 271       #     <script type="text/javascript" src="/javascripts/head.js"></script>
 272       #     <script type="text/javascript" src="/javascripts/body.js"></script>
 273       #     <script type="text/javascript" src="/javascripts/tail.js"></script>
 274       def self.register_javascript_expansion(expansions)
 275         JavaScriptSources.expansions.merge!(expansions)
 276       end
 277
 278       # Register one or more stylesheet files to be included when <tt>symbol</tt>
 279       # is passed to <tt>stylesheet_link_tag</tt>. This method is typically intended
 280       # to be called from plugin initialization to register stylesheet files
 281       # that the plugin installed in <tt>public/stylesheets</tt>.
 282       #
 283       #   ActionView::Helpers::AssetTagHelper.register_stylesheet_expansion :monkey => ["head", "body", "tail"]
 284       #
 285       #   stylesheet_link_tag :monkey # =>
 286       #     <link href="/stylesheets/head.css"  media="screen" rel="stylesheet" type="text/css" />
 287       #     <link href="/stylesheets/body.css"  media="screen" rel="stylesheet" type="text/css" />
 288       #     <link href="/stylesheets/tail.css"  media="screen" rel="stylesheet" type="text/css" />
 289       def self.register_stylesheet_expansion(expansions)
 290         StylesheetSources.expansions.merge!(expansions)
 291       end
 292
 293       # Register one or more additional JavaScript files to be included when
 294       # <tt>javascript_include_tag :defaults</tt> is called. This method is
 295       # typically intended to be called from plugin initialization to register additional
 296       # .js files that the plugin installed in <tt>public/javascripts</tt>.
 297       def self.register_javascript_include_default(*sources)
 298         JavaScriptSources.expansions[:defaults].concat(sources)
 299       end
 300
 301       def self.reset_javascript_include_default #:nodoc:
 302         JavaScriptSources.expansions[:defaults] = JAVASCRIPT_DEFAULT_SOURCES.dup
 303       end
 304
 305       # Computes the path to a stylesheet asset in the public stylesheets directory.
 306       # If the +source+ filename has no extension, <tt>.css</tt> will be appended.
 307       # Full paths from the document root will be passed through.
 308       # Used internally by +stylesheet_link_tag+ to build the stylesheet path.
 309       #
 310       # ==== Examples
 311       #   stylesheet_path "style" # => /stylesheets/style.css
 312       #   stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
 313       #   stylesheet_path "/dir/style.css" # => /dir/style.css
 314       #   stylesheet_path "http://www.railsapplication.com/css/style" # => http://www.railsapplication.com/css/style.css
 315       #   stylesheet_path "http://www.railsapplication.com/css/style.js" # => http://www.railsapplication.com/css/style.css
 316       def stylesheet_path(source)
 317         StylesheetTag.new(self, @controller, source).public_path
 318       end
 319       alias_method :path_to_stylesheet, :stylesheet_path # aliased to avoid conflicts with a stylesheet_path named route
 320
 321       # Returns a stylesheet link tag for the sources specified as arguments. If
 322       # you don't specify an extension, <tt>.css</tt> will be appended automatically.
 323       # You can modify the link attributes by passing a hash as the last argument.
 324       #
 325       # ==== Examples
 326       #   stylesheet_link_tag "style" # =>
 327       #     <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />
 328       #
 329       #   stylesheet_link_tag "style.css" # =>
 330       #     <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />
 331       #
 332       #   stylesheet_link_tag "http://www.railsapplication.com/style.css" # =>
 333       #     <link href="http://www.railsapplication.com/style.css" media="screen" rel="stylesheet" type="text/css" />
 334       #
 335       #   stylesheet_link_tag "style", :media => "all" # =>
 336       #     <link href="/stylesheets/style.css" media="all" rel="stylesheet" type="text/css" />
 337       #
 338       #   stylesheet_link_tag "style", :media => "print" # =>
 339       #     <link href="/stylesheets/style.css" media="print" rel="stylesheet" type="text/css" />
 340       #
 341       #   stylesheet_link_tag "random.styles", "/css/stylish" # =>
 342       #     <link href="/stylesheets/random.styles" media="screen" rel="stylesheet" type="text/css" />
 343       #     <link href="/css/stylish.css" media="screen" rel="stylesheet" type="text/css" />
 344       #
 345       # You can also include all styles in the stylesheets directory using <tt>:all</tt> as the source:
 346       #
 347       #   stylesheet_link_tag :all # =>
 348       #     <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
 349       #     <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
 350       #     <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />
 351       #
 352       # If you want Rails to search in all the subdirectories under stylesheets, you should explicitly set <tt>:recursive</tt>:
 353       #
 354       #   stylesheet_link_tag :all, :recursive => true
 355       #
 356       # == Caching multiple stylesheets into one
 357       #
 358       # You can also cache multiple stylesheets into one file, which requires less HTTP connections and can better be
 359       # compressed by gzip (leading to faster transfers). Caching will only happen if ActionController::Base.perform_caching
 360       # is set to true (which is the case by default for the Rails production environment, but not for the development
 361       # environment). Examples:
 362       #
 363       # ==== Examples
 364       #   stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is false =>
 365       #     <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
 366       #     <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
 367       #     <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />
 368       #
 369       #   stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is true =>
 370       #     <link href="/stylesheets/all.css"  media="screen" rel="stylesheet" type="text/css" />
 371       #
 372       #   stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when ActionController::Base.perform_caching is false =>
 373       #     <link href="/stylesheets/shop.css"  media="screen" rel="stylesheet" type="text/css" />
 374       #     <link href="/stylesheets/cart.css"  media="screen" rel="stylesheet" type="text/css" />
 375       #     <link href="/stylesheets/checkout.css" media="screen" rel="stylesheet" type="text/css" />
 376       #
 377       #   stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when ActionController::Base.perform_caching is true =>
 378       #     <link href="/stylesheets/payment.css"  media="screen" rel="stylesheet" type="text/css" />
 379       #
 380       # The <tt>:recursive</tt> option is also available for caching:
 381       #
 382       #   stylesheet_link_tag :all, :cache => true, :recursive => true
 383       def stylesheet_link_tag(*sources)
 384         options = sources.extract_options!.stringify_keys
 385         cache   = options.delete("cache")
 386         recursive = options.delete("recursive")
 387
 388         if ActionController::Base.perform_caching && cache
 389           joined_stylesheet_name = (cache == true ? "all" : cache) + ".css"
 390           joined_stylesheet_path = File.join(STYLESHEETS_DIR, joined_stylesheet_name)
 391
 392           unless File.exists?(joined_stylesheet_path)
 393             StylesheetSources.create(self, @controller, sources, recursive).write_asset_file_contents(joined_stylesheet_path)
 394           end
 395           stylesheet_tag(joined_stylesheet_name, options)
 396         else
 397           StylesheetSources.create(self, @controller, sources, recursive).expand_sources.collect { |source|
 398             stylesheet_tag(source, options)
 399           }.join("\n")
 400         end
 401       end
 402
 403       # Computes the path to an image asset in the public images directory.
 404       # Full paths from the document root will be passed through.
 405       # Used internally by +image_tag+ to build the image path.
 406       #
 407       # ==== Examples
 408       #   image_path("edit")                                         # => /images/edit
 409       #   image_path("edit.png")                                     # => /images/edit.png
 410       #   image_path("icons/edit.png")                               # => /images/icons/edit.png
 411       #   image_path("/icons/edit.png")                              # => /icons/edit.png
 412       #   image_path("http://www.railsapplication.com/img/edit.png") # => http://www.railsapplication.com/img/edit.png
 413       def image_path(source)
 414         ImageTag.new(self, @controller, source).public_path
 415       end
 416       alias_method :path_to_image, :image_path # aliased to avoid conflicts with an image_path named route
 417
 418       # Returns an html image tag for the +source+. The +source+ can be a full
 419       # path or a file that exists in your public images directory.
 420       #
 421       # ==== Options
 422       # You can add HTML attributes using the +options+. The +options+ supports
 423       # three additional keys for convenience and conformance:
 424       #
 425       # * <tt>:alt</tt>  - If no alt text is given, the file name part of the
 426       #   +source+ is used (capitalized and without the extension)
 427       # * <tt>:size</tt> - Supplied as "{Width}x{Height}", so "30x45" becomes
 428       #   width="30" and height="45". <tt>:size</tt> will be ignored if the
 429       #   value is not in the correct format.
 430       # * <tt>:mouseover</tt> - Set an alternate image to be used when the onmouseover
 431       #   event is fired, and sets the original image to be replaced onmouseout.
 432       #   This can be used to implement an easy image toggle that fires on onmouseover.
 433       #
 434       # ==== Examples
 435       #  image_tag("icon")  # =>
 436       #    <img src="/images/icon" alt="Icon" />
 437       #  image_tag("icon.png")  # =>
 438       #    <img src="/images/icon.png" alt="Icon" />
 439       #  image_tag("icon.png", :size => "16x10", :alt => "Edit Entry")  # =>
 440       #    <img src="/images/icon.png" width="16" height="10" alt="Edit Entry" />
 441       #  image_tag("/icons/icon.gif", :size => "16x16")  # =>
 442       #    <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />
 443       #  image_tag("/icons/icon.gif", :height => '32', :width => '32') # =>
 444       #    <img alt="Icon" height="32" src="/icons/icon.gif" width="32" />
 445       #  image_tag("/icons/icon.gif", :class => "menu_icon") # =>
 446       #    <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
 447       #  image_tag("mouse.png", :mouseover => "/images/mouse_over.png") # =>
 448       #    <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
 449       #  image_tag("mouse.png", :mouseover => image_path("mouse_over.png")) # =>
 450       #    <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
 451       def image_tag(source, options = {})
 452         options.symbolize_keys!
 453
 454         options[:src] = path_to_image(source)
 455         options[:alt] ||= File.basename(options[:src], '.*').split('.').first.to_s.capitalize
 456
 457         if size = options.delete(:size)
 458           options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
 459         end
 460
 461         if mouseover = options.delete(:mouseover)
 462           options[:onmouseover] = "this.src='#{image_path(mouseover)}'"
 463           options[:onmouseout]  = "this.src='#{image_path(options[:src])}'"
 464         end
 465
 466         tag("img", options)
 467       end
 468
 469       private
 470         def javascript_src_tag(source, options)
 471           content_tag("script", "", { "type" => Mime::JS, "src" => path_to_javascript(source) }.merge(options))
 472         end
 473
 474         def stylesheet_tag(source, options)
 475           tag("link", { "rel" => "stylesheet", "type" => Mime::CSS, "media" => "screen", "href" => html_escape(path_to_stylesheet(source)) }.merge(options), false, false)
 476         end
 477
 478         module ImageAsset
 479           DIRECTORY = 'images'.freeze
 480
 481           def directory
 482             DIRECTORY
 483           end
 484
 485           def extension
 486             nil
 487           end
 488         end
 489
 490         module JavaScriptAsset
 491           DIRECTORY = 'javascripts'.freeze
 492           EXTENSION = 'js'.freeze
 493
 494           def public_directory
 495             JAVASCRIPTS_DIR
 496           end
 497
 498           def directory
 499             DIRECTORY
 500           end
 501
 502           def extension
 503             EXTENSION
 504           end
 505         end
 506
 507         module StylesheetAsset
 508           DIRECTORY = 'stylesheets'.freeze
 509           EXTENSION = 'css'.freeze
 510
 511           def public_directory
 512             STYLESHEETS_DIR
 513           end
 514
 515           def directory
 516             DIRECTORY
 517           end
 518
 519           def extension
 520             EXTENSION
 521           end
 522         end
 523
 524         class AssetTag
 525           extend ActiveSupport::Memoizable
 526
 527           Cache = {}
 528           CacheGuard = Mutex.new
 529
 530           ProtocolRegexp = %r{^[-a-z]+://}.freeze
 531
 532           def initialize(template, controller, source, include_host = true)
 533             # NOTE: The template arg is temporarily needed for a legacy plugin
 534             # hook that is expected to call rewrite_asset_path on the
 535             # template. This should eventually be removed.
 536             @template = template
 537             @controller = controller
 538             @source = source
 539             @include_host = include_host
 540             @cache_key = if controller.respond_to?(:request)
 541               [self.class.name,controller.request.protocol,
 542                ActionController::Base.asset_host,
 543                ActionController::Base.relative_url_root,
 544                source, include_host]
 545             else
 546               [self.class.name,ActionController::Base.asset_host, source, include_host]
 547             end
 548           end
 549
 550           def public_path
 551             compute_public_path(@source)
 552           end
 553           memoize :public_path
 554
 555           def asset_file_path
 556             File.join(ASSETS_DIR, public_path.split('?').first)
 557           end
 558           memoize :asset_file_path
 559
 560           def contents
 561             File.read(asset_file_path)
 562           end
 563
 564           def mtime
 565             File.mtime(asset_file_path)
 566           end
 567
 568           private
 569             def request
 570               @controller.request
 571             end
 572
 573             def request?
 574               @controller.respond_to?(:request)
 575             end
 576
 577             # Add the the extension +ext+ if not present. Return full URLs otherwise untouched.
 578             # Prefix with <tt>/dir/</tt> if lacking a leading +/+. Account for relative URL
 579             # roots. Rewrite the asset path for cache-busting asset ids. Include
 580             # asset host, if configured, with the correct request protocol.
 581             def compute_public_path(source)
 582               if source =~ ProtocolRegexp
 583                 source += ".#{extension}" if missing_extension?(source)
 584                 source = prepend_asset_host(source)
 585                 source
 586               else
 587                 CacheGuard.synchronize do
 588                   Cache[@cache_key] ||= begin
 589                     source += ".#{extension}" if missing_extension?(source) || file_exists_with_extension?(source)
 590                     source = "/#{directory}/#{source}" unless source[0] == ?/
 591                     source = rewrite_asset_path(source)
 592                     source = prepend_relative_url_root(source)
 593                     source = prepend_asset_host(source)
 594                     source
 595                   end
 596                 end
 597               end
 598             end
 599
 600             def missing_extension?(source)
 601               extension && File.extname(source).blank?
 602             end
 603
 604             def file_exists_with_extension?(source)
 605               extension && File.exist?(File.join(ASSETS_DIR, directory, "#{source}.#{extension}"))
 606             end
 607
 608             def prepend_relative_url_root(source)
 609               relative_url_root = ActionController::Base.relative_url_root
 610               if request? && @include_host && source !~ %r{^#{relative_url_root}/}
 611                 "#{relative_url_root}#{source}"
 612               else
 613                 source
 614               end
 615             end
 616
 617             def prepend_asset_host(source)
 618               if @include_host && source !~ ProtocolRegexp
 619                 host = compute_asset_host(source)
 620                 if request? && !host.blank? && host !~ ProtocolRegexp
 621                   host = "#{request.protocol}#{host}"
 622                 end
 623                 "#{host}#{source}"
 624               else
 625                 source
 626               end
 627             end
 628
 629             # Pick an asset host for this source. Returns +nil+ if no host is set,
 630             # the host if no wildcard is set, the host interpolated with the
 631             # numbers 0-3 if it contains <tt>%d</tt> (the number is the source hash mod 4),
 632             # or the value returned from invoking the proc if it's a proc.
 633             def compute_asset_host(source)
 634               if host = ActionController::Base.asset_host
 635                 if host.is_a?(Proc)
 636                   case host.arity
 637                   when 2
 638                     host.call(source, request)
 639                   else
 640                     host.call(source)
 641                   end
 642                 else
 643                   (host =~ /%d/) ? host % (source.hash % 4) : host
 644                 end
 645               end
 646             end
 647
 648             # Use the RAILS_ASSET_ID environment variable or the source's
 649             # modification time as its cache-busting asset id.
 650             def rails_asset_id(source)
 651               if asset_id = ENV["RAILS_ASSET_ID"]
 652                 asset_id
 653               else
 654                 path = File.join(ASSETS_DIR, source)
 655
 656                 if File.exist?(path)
 657                   File.mtime(path).to_i.to_s
 658                 else
 659                   ''
 660                 end
 661               end
 662             end
 663
 664             # Break out the asset path rewrite in case plugins wish to put the asset id
 665             # someplace other than the query string.
 666             def rewrite_asset_path(source)
 667               if @template.respond_to?(:rewrite_asset_path)
 668                 # DEPRECATE: This way to override rewrite_asset_path
 669                 @template.send(:rewrite_asset_path, source)
 670               else
 671                 asset_id = rails_asset_id(source)
 672                 if asset_id.blank?
 673                   source
 674                 else
 675                   "#{source}?#{asset_id}"
 676                 end
 677               end
 678             end
 679         end
 680
 681         class ImageTag < AssetTag
 682           include ImageAsset
 683         end
 684
 685         class JavaScriptTag < AssetTag
 686           include JavaScriptAsset
 687         end
 688
 689         class StylesheetTag < AssetTag
 690           include StylesheetAsset
 691         end
 692
 693         class AssetCollection
 694           extend ActiveSupport::Memoizable
 695
 696           Cache = {}
 697           CacheGuard = Mutex.new
 698
 699           def self.create(template, controller, sources, recursive)
 700             CacheGuard.synchronize do
 701               key = [self, sources, recursive]
 702               Cache[key] ||= new(template, controller, sources, recursive).freeze
 703             end
 704           end
 705
 706           def initialize(template, controller, sources, recursive)
 707             # NOTE: The template arg is temporarily needed for a legacy plugin
 708             # hook. See NOTE under AssetTag#initialize for more details
 709             @template = template
 710             @controller = controller
 711             @sources = sources
 712             @recursive = recursive
 713           end
 714
 715           def write_asset_file_contents(joined_asset_path)
 716             FileUtils.mkdir_p(File.dirname(joined_asset_path))
 717             File.open(joined_asset_path, "w+") { |cache| cache.write(joined_contents) }
 718             mt = latest_mtime
 719             File.utime(mt, mt, joined_asset_path)
 720           end
 721
 722           private
 723             def determine_source(source, collection)
 724               case source
 725               when Symbol
 726                 collection[source] || raise(ArgumentError, "No expansion found for #{source.inspect}")
 727               else
 728                 source
 729               end
 730             end
 731
 732             def validate_sources!
 733               @sources.collect { |source| determine_source(source, self.class.expansions) }.flatten
 734             end
 735
 736             def all_asset_files
 737               path = [public_directory, ('**' if @recursive), "*.#{extension}"].compact
 738               Dir[File.join(*path)].collect { |file|
 739                 file[-(file.size - public_directory.size - 1)..-1].sub(/\.\w+$/, '')
 740               }.sort
 741             end
 742
 743             def tag_sources
 744               expand_sources.collect { |source| tag_class.new(@template, @controller, source, false) }
 745             end
 746
 747             def joined_contents
 748               tag_sources.collect { |source| source.contents }.join("\n\n")
 749             end
 750
 751             # Set mtime to the latest of the combined files to allow for
 752             # consistent ETag without a shared filesystem.
 753             def latest_mtime
 754               tag_sources.map { |source| source.mtime }.max
 755             end
 756         end
 757
 758         class JavaScriptSources < AssetCollection
 759           include JavaScriptAsset
 760
 761           EXPANSIONS = { :defaults => JAVASCRIPT_DEFAULT_SOURCES.dup }
 762
 763           def self.expansions
 764             EXPANSIONS
 765           end
 766
 767           APPLICATION_JS = "application".freeze
 768           APPLICATION_FILE = "application.js".freeze
 769
 770           def expand_sources
 771             if @sources.include?(:all)
 772               assets = all_asset_files
 773               ((defaults.dup & assets) + assets).uniq!
 774             else
 775               expanded_sources = validate_sources!
 776               expanded_sources << APPLICATION_JS if include_application?
 777               expanded_sources
 778             end
 779           end
 780           memoize :expand_sources
 781
 782           private
 783             def tag_class
 784               JavaScriptTag
 785             end
 786
 787             def defaults
 788               determine_source(:defaults, self.class.expansions)
 789             end
 790
 791             def include_application?
 792               @sources.include?(:defaults) && File.exist?(File.join(JAVASCRIPTS_DIR, APPLICATION_FILE))
 793             end
 794         end
 795
 796         class StylesheetSources < AssetCollection
 797           include StylesheetAsset
 798
 799           EXPANSIONS = {}
 800
 801           def self.expansions
 802             EXPANSIONS
 803           end
 804
 805           def expand_sources
 806             @sources.first == :all ? all_asset_files : validate_sources!
 807           end
 808           memoize :expand_sources
 809
 810           private
 811             def tag_class
 812               StylesheetTag
 813             end
 814         end
 815     end
 816   end
 817 end