Module: EasyMultipart::Helper

Defined in:
lib/easy_multipart/helper.rb

Overview

This module provides methods for generating HTML body parts that include embedded images.

Instance Method Summary collapse

Instance Method Details

#normalize_content_id(content_id) ⇒ Object

XXX We should use a method in EasyMultipart::Base so we can share code with format_content_id.



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# File 'lib/easy_multipart/helper.rb', line 62

def normalize_content_id(content_id) #:nodoc:
  "#{content_id}"
end

#related_image_tag(source, image_options = {}, related_options = {}) ⇒ Object

Returns an HTML image tag for the source. The source can be a full path or a file that exists in your public images directory. Alternatively, it can be a hash with these mandatory keys:

  • :body - An object representing the image content. Any kind of object can be used, as long as it responds to :to_s.

  • :content_id - A string that uniquely identifies the image within the current document.

Options

You can add HTML attributes using the image_options. You can pass any option accepted by image_tag.

You can pass additional options through related_options:

  • :content_type - The value to use for the Content-Type MIME header. If not provided it defaults to ‘image/png’.

  • :transfer_encoding - The value to use for the Transfer-Encoding MIME header. If not provided it defaults to ‘base64’. Unless you have special requirements, you should not provide a value for this key.

  • :content_disposition - The value to use for the Content-Disposition MIME header. If not provided it defaults to not generating a Content-Disposition header.



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# File 'lib/easy_multipart/helper.rb', line 29

def related_image_tag(source, image_options = {}, related_options = {})
  related_options.reverse_merge! :content_type => 'image/png',
                                  :transfer_encoding => 'base64'
  
  if source.is_a?(Hash)
    unless source.has_key?(:content_id)
      raise "You must specify a :content_id if you provide a :body"
    end
    
    content_id  = source[:content_id]
    source      = source[:body].to_s
  else
    if source.first != '/'
      assets_dir  = defined?(Rails.public_path) ? Rails.public_path : "public"
      source      = File.join(assets_dir, "images", source)
    end
    
    content_id  = File.basename(source)
    source      = File.read(source)
  end
  content_id = normalize_content_id(content_id)
  
  @related[content_id] = [related_options[:content_type], lambda do |image|
    image.body                = source
    image.transfer_encoding   = related_options[:transfer_encoding]
    image.content_disposition = related_options[:content_disposition] # default is none
  end]
  
  @template.tag(:img, image_options.merge(:src => "cid:#{content_id}"))
end