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 unless @dimensions
      begin
        Integer(@dimensions[style.to_s]['width'])
      rescue
        # Integer() throws an exception if it can't do it,
        # we'll eat the exception incase any of our items don't have dimensions saved
        return nil
      end
    end

    def height style = :original
      @dimensions = dimensions unless @dimensions
      begin
        Integer(@dimensions[style.to_s]['height'])
      rescue
        # Integer() throws an exception if it can't do it,
        # we'll eat the exception incase any of our items don't have dimensions saved
        return nil
      end
    end

    def dimensions
      unless @dimensions
        dim = instance_read(:dimensions)
        @dimensions = JSON.parse(dim) unless dim.nil?
      end
      @dimensions
    end
  end

end

module Paperclip::Dimensions

  def save_image_dimensions
    attachments = []
    self.attributes.each do |attr|
      attr_name = nil
      attr_match = attr[0].match(/(.*)_file_name/)
      attr_name = attr_match[1] unless attr_match.nil?

      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
      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