Paperclip initializer to provide dimensions data for the original attachment

paperclip_initializer.rb

# width & height attributes for the original image only
# since style dimensions are already known
#
# Migration to add width & height attribtues for the original attachment
#
#     add_column :<model>, :<attachment>_file_width, :integer
#     add_column :<model>, :<attachment>_file_height, :integer
#
#
#     class Document < ActiveRecord::Base
#       # paperclip
#       #
#       has_attached_file :file, :styles => { :medium => "300x300>" }
#
#       before_save :save_dimensions
#
#       def save_dimensions
#         # file.dirty? helps the app from hanging when updating with no new file
#         if file.dirty? && file.image?
#           geom = Paperclip::Geometry.from_file(file.queued_for_write[:original])
#           file.width  = geom.width
#           file.height = geom.height
#         end
#       end
#     end
#
#
#     doc = Document.create :file => <an image>
#     doc.file.width  #=> returns a number
#     doc.file.height #=> returns a number
#
# TODOs
# * Real-time geometry if the width & height are not originally set
# * Push `save_dimensions` callback into Paperclip so we don't have to set it all the time
#     * allow `is_image?` to work off of provided content_types
# * Clear `:file_width` & `:file_height` attributes when an attachment has no dimensions or is cleared

module Paperclip
  class Attachment
    def width
      instance_read(:file_width)
    end

    def height
      instance_read(:file_height)
    end

    def width=(val)
      instance_write(:file_width, val)
    end

    def height=(val)
      instance_write(:file_height, val)
    end

    def is_image?
      content_type =~ %r{^(image|(x-)?application)/(png|pjpeg|jpeg|jpg|png|gif)$}
    end
  end
end