thubmnail_with_dimensions.rb

# Filename: RAILS_ROOT/config/initializers/paperclip_thumbnail_with_dimensions.rb
# Required Configuration in the model
#
#   include Paperclip::Dimensions
#
#   has_attached_file :image,
#    :styles => {
#      :thumbnail => {
#        :geometry => "100x100>",
#        :format => :png
#      },
#      :some_other_style => {
#        :geometry => "640x480>"
#      }
#    }
#
#   after_post_process :save_image_dimensions
#
# To get a dimension in a view just do:
# <%= @object.image.width(:thumbnail) %> # Gives the width of the thumbnail
# <%= @object.image.height(:thumbnail) %> # Gives the height of the thumbnail
# <%= @object.image.width %> # Gives the width of the original
# <%= @object.image.dimensions %> Will return the dimensions hash


module Paperclip
  class Attachment
    def width style = :original
      @dimensions ||= dimensions
      Integer(@dimensions[style.to_s]['width']) rescue nil
    end

    def height style = :original
      @dimensions ||= dimensions
      Integer(@dimensions[style.to_s]['height']) rescue nil
    end

    def dimensions
      @dimensions ||= JSON.parse(dim) if dim = instance_read(:dimensions)
    end
  end
end

module Paperclip::Dimensions
  def save_image_dimensions
    attachments = []
    self.attributes.each do |attr|
      attr_match = attr[0].match(/(.*)_file_name/)
      attr_name = attr_match[1] if attr_match

      if attr_match && self.respond_to?(attr_name)
        potential = self.send attr_name
        attachments << potential if potential.instance_of? Paperclip::Attachment
      end
    end

#    Event may be fired once per attachment, but I'm not sure how to distinguish
    attachments.each do |attachment|
      dimensions = attachment.dimensions || {} # make sure he have a hash

      attachment.styles.each do |style_prop|
        style = style_prop[0]

        dimensions[style] = Paperclip::Geometry.from_file(attachment.queued_for_write[style])
      end

#     once for the original
      dimensions[:original] = Paperclip::Geometry.from_file(attachment.queued_for_write[:original])

      attachment.instance_write(:dimensions, dimensions.to_json)
    end
  end
end