paperclip_initializer.rb

# Para salvar a altura e largura das imagens enviadas pelo plugin paperclip, utilize o callback abaixo
# 
# class Document < ActiveRecord::Base
#   
#   has_attached_file :document, :styles => { :medium => "300x300>" }
#   
#   before_save :save_dimensions
#   
#   def save_dimensions
#     if document.image?
#       self.width = document.width
#       self.height = document.height
#     end
#   end
#   
# end
 
module Paperclip
  class Attachment
    def get_and_cache_dimensions(style = default_style)
      @_dimensions ||= {}
      @_dimensions[style] ||= Paperclip::Geometry.from_file(to_file(style))
    end

    def width(style = default_style)
      get_and_cache_dimensions(style)
      @_dimensions[style].width
    end
 
    def height(style = default_style)
      get_and_cache_dimensions(style)
      @_dimensions[style].height
    end
    
    def image?(style = default_style)
      to_file(style).image?
    end
  end
  
  module Upfile
    def image?
      ["image/jpeg", "image/tiff", "image/png", "image/gif", "image/bmp"].include?(content_type)
    end
  end
end