Class: Rack::Html5

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/html5.rb

Overview

Rack::Html5 sets custom headers for each HTML5 feature the browser supports. It does this by parsing the user agent and matching the features to the browser version based on information provided on: caniuse.com/#eras=farpast,past,now&cats=HTML5&statuses=rec,pr,cr,wd,ietf&nodetails=1

The headers that are being set:

  • HTTP_X_DETECTED_BROWSER: Browser that has been DETECTED, eg.: Firefox

  • HTTP_X_DETECTED_VERSION: Version of the browser that has been DETECTED, eg.: 3.6.6

  • HTTP_X_SUPPORTS_HTML5_WYSIWYG: WYSIWYG editable elements

  • HTTP_X_SUPPORTS_HTML5_CLASSNAME: getElementsByClassName

  • HTTP_X_SUPPORTS_HTML5_ELEMENTS: Stylable HTML5 elements

  • HTTP_X_SUPPORTS_HTML5_CANVAS: Canvas (basic support)

  • HTTP_X_SUPPORTS_HTML5_MESSAGING: Cross-document messaging

  • HTTP_X_SUPPORTS_HTML5_AUDIO: Audio element

  • HTTP_X_SUPPORTS_HTML5_VIDEO: Video element

  • HTTP_X_SUPPORTS_HTML5_TEXTAPI: Text API for canvas

  • HTTP_X_SUPPORTS_HTML5_DRAGANDDROP: Drag and drop

  • HTTP_X_SUPPORTS_HTML5_OFFLINE: Offline web applications

  • HTTP_X_SUPPORTS_HTML5_SVG: Inline SVG

  • HTTP_X_SUPPORTS_HTML5_FORMS: Form features (Web Forms 2.0)

Please note:

  • If the feature is not supported, the header will not be set.

  • If a browser implements a feature only partially, the corresponding header will not be set.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Html5

Returns a new instance of Html5.



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# File 'lib/rack/html5.rb', line 28

def initialize(app)
  @app = app
  @features = []      
end

Instance Attribute Details

#browser ⇒ Object

Returns the value of attribute browser.



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# File 'lib/rack/html5.rb', line 26

def browser
  @browser
end

#env ⇒ Object

Returns the value of attribute env.



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# File 'lib/rack/html5.rb', line 26

def env
  @env
end

#features ⇒ Object

Returns the value of attribute features.



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# File 'lib/rack/html5.rb', line 26

def features
  @features
end

#user_agent ⇒ Object

Returns the value of attribute user_agent.



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# File 'lib/rack/html5.rb', line 26

def user_agent
  @user_agent
end

#version ⇒ Object

Returns the value of attribute version.



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# File 'lib/rack/html5.rb', line 26

def version
  @version
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/html5.rb', line 41

def call(env)
  @env = env      
  @user_agent = @env['HTTP_USER_AGENT']
  
  detect_browser
  detect_features
  generate_headers
  
  @app.call(@env)
end

#comparable_version(v) ⇒ Object

New features are only being shipped with major version updated. So we’ll be on the safe side using the first two parts of the version number for comparisation. eg. version 10.5.6a will be cut down to 10.5, dots will be stripped, return value would be 105



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# File 'lib/rack/html5.rb', line 81

def comparable_version(v)
  v.split(".")[0..1].join
end

#detect_browser ⇒ Object

Detects the browser and version based on the user agent



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# File 'lib/rack/html5.rb', line 53

def detect_browser     
  user_agent_matcher.each do |browser, regexp|        
    match = @user_agent.match(regexp)
    version = match.captures.first if match
    if version
      @browser = browser
      @version = version
      break
    end
  end
end

#detect_features ⇒ Object

Detects the HTML5 features the browser supports



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# File 'lib/rack/html5.rb', line 66

def detect_features
  return unless @browser && @version
  feature_mapping[browser].each do |feature, version|
     if version           
       raise "Versions are not comparable: #{version}, #{@version}" if comparable_version(version).length != comparable_version(@version).length
       if comparable_version(@version) >= comparable_version(version)
         @features << feature
       end
     end
   end
end

#feature_mapping ⇒ Object

Feature to browser version mapping according to the information provided on: caniuse.com/#eras=farpast,past,now&cats=HTML5&statuses=rec,pr,cr,wd,ietf&nodetails=1



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# File 'lib/rack/html5.rb', line 86

def feature_mapping
  {
    :firefox => {          
      :wysiwyg => "3.5",
      :classname => "3.0",
      :elements => "3.0",
      :canvas => "3.0",
      :messaging => "3.0",
      :audio => "3.5",
      :video => "3.5", 
      :textapi => "3.5",
      :draganddrop => "3.5", 
      :offline => "3.5", 
      :forms => nil,
      :svg => nil
    },
    :ie => {          
      :wysiwyg => "6.0",
      :classname => nil,
      :elements => nil,
      :canvas => nil,
      :messaging => "8.0",
      :audio => nil,
      :video => nil,
      :textapi => nil,
      :draganddrop => nil,
      :offline => nil,
      :forms => nil,
      :svg => nil
    }, 
    :opera => {
      :wysiwyg => "10.1",
      :classname => "10.1",
      :elements => "10.1",
      :canvas => "10.1",
      :messaging => "10.1",
      :audio => "10.5",
      :video => "10.5",
      :textapi => "10.5",
      :draganddrop => nil,
      :offline => "10.6",
      :forms => "10.1",
      :svg => nil          
    },         
    :chrome => {
      :wysiwyg => "3.0",
      :classname => "3.0",
      :elements => "3.0",
      :canvas => "3.0",
      :messaging => "3.0",
      :audio => "3.0",
      :video => "3.0",
      :textapi => "3.0",
      :draganddrop => "3.0",
      :offline => "4.0",
      :forms => nil,
      :svg => nil          
    }, 
    :safari => {
      :wysiwyg => "3.2",
      :classname => "3.2",
      :elements => "3.2",
      :canvas => "3.2",
      :messaging => "4.0",
      :audio => "3.2",
      :video => "3.2",
      :textapi => "4.2",
      :draganddrop => "4.0",
      :offline => "4.0",
      :forms => nil,
      :svg => nil          
    }
  }
end

#generate_headers ⇒ Object 



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# File 'lib/rack/html5.rb', line 33

def generate_headers
  @env['HTTP_X_DETECTED_VERSION'] = version
  @env['HTTP_X_DETECTED_BROWSER'] = browser.to_s
  @features.each do |feature|
    @env["HTTP_X_SUPPORTS_HTML5_#{feature.to_s.upcase}"] = "true"
  end
end

#user_agent_matcher ⇒ Object

Browser to user agent matching



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# File 'lib/rack/html5.rb', line 162

def user_agent_matcher
  regexp_version = /((\d+\.?)+)/
  { 
    :firefox => /Firefox\/#{regexp_version}/, # eg. Firefox/1.5.0.12
    :ie => /MSIE #{regexp_version}/, # eg. compatible; MSIE 7.0;
    :chrome => /Chrome\/#{regexp_version}/, # eg. Chrome/5.0.307.11 Safari/532.9
    :safari => /AppleWebKit\/.*Version\/#{regexp_version}/, # eg. AppleWebKit/531.21.8 Version/4.0.4 Safari/531.21.10              
    :opera => /Opera\/#{regexp_version}/, # eg. Opera/9.80
  }
end