Class: Juicer::ImageEmbed

Inherits:
Object
  • Object
show all
Includes:
Chainable
Defined in:
lib/juicer/image_embed.rb

Overview

The ImageEmbed is a tool that can parse a CSS file and substitute all referenced URLs by a data uri

Only local resources will be processed this way, external resources referenced by absolute urls will be left alone

Constant Summary collapse

SIZE_LIMIT =

The maximum supported limit for modern browsers, See the Readme.rdoc for details

32768

Instance Method Summary collapse

Methods included from Chainable

included, #next_in_chain, #next_in_chain=

Constructor Details

#initialize(options = {}) ⇒ ImageEmbed

Returns a new instance of ImageEmbed.



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# File 'lib/juicer/image_embed.rb', line 28

def initialize(options = {})
  @document_root = options[:document_root]
  @document_root.sub!(%r{/?$}, "") if @document_root # Remove trailing slash
  @type = options[:type] || :none
  @contents = nil
  @hosts = options[:hosts]
  @path_resolver = Juicer::Asset::PathResolver.new(:document_root => options[:document_root],
                                                   :hosts => options[:hosts])
end

Instance Method Details

#embed_data_uri(path) ⇒ Object 



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# File 'lib/juicer/image_embed.rb', line 86

def embed_data_uri( path )
  new_path = path
  
  supported_file_matches = path.match( /(?:\.)(png|gif|jpg|jpeg)(?:\?embed=true)$/i )
  filetype = supported_file_matches[1] if supported_file_matches
  
  if ( filetype )        
    filename = path.gsub('?embed=true','')      
    
    # check if file exists, throw an error if it doesn't exist
    if File.exist?( filename )
      
      # read contents of file into memory              
      content = File.read( filename )
      content_type = "image/#{filetype}"
      
      # encode the url
      new_path = Datafy::make_data_uri( content, content_type )
    else
      puts "Unable to locate file #{filename} on local file system, skipping image embedding"
    end
  end
  return new_path
end

#save(file, output = nil) ⇒ Object

Update file. If no output is provided, the input file is overwritten



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# File 'lib/juicer/image_embed.rb', line 41

def save(file, output = nil)
  return unless @type == :data_uri

  output_file = output || file
  @contents = File.read(file)
  used = []

  @path_resolver = Juicer::Asset::PathResolver.new(:document_root => @document_root,
                                                   :hosts => @hosts,
                                                   :base => File.dirname(file))

  assets = urls(file)

  # TODO: Remove "?embed=true" from duplicate urls
  duplicates = duplicate_urls(assets)

  if duplicates.length > 0
    Juicer::LOGGER.warn("Duplicate image urls detected, these images will not be embedded: #{duplicates.collect { |v| v.gsub('?embed=true', '') }.inspect}") 
  end

  assets.each do |asset|
    begin
      next if used.include?(asset) || duplicates.include?(asset.path)
      used << asset
      
      # make sure we do not exceed SIZE_LIMIT
      new_path = embed_data_uri(asset.filename)

      if new_path.length < SIZE_LIMIT
        # replace the url in the css file with the data uri
        @contents.gsub!(asset.path, embed_data_uri(asset.filename)) if asset.filename.match( /\?embed=true$/ )
      else
        Juicer::LOGGER.warn("The final data uri for the image located at #{asset.path.gsub('?embed=true', '')} exceeds #{SIZE_LIMIT} and will not be embedded to maintain compatability.") 
      end
    rescue Errno::ENOENT
      puts "Unable to locate file #{asset.path}, skipping image embedding"
    end
  end

  File.open(output || file, "w") { |f| f.puts @contents }
  @contents = nil
end

#size_limit ⇒ Object

Returns the size limit



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# File 'lib/juicer/image_embed.rb', line 24

def size_limit
  SIZE_LIMIT
end

#urls(file) ⇒ Object

Returns all referenced URLs in file.



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# File 'lib/juicer/image_embed.rb', line 114

def urls(file)
  @contents = File.read(file) unless @contents

  @contents.scan(/url\([\s"']*([^\)"'\s]*)[\s"']*\)/m).collect do |match|
    @path_resolver.resolve(match.first)
  end
end