Paperclip watermarking processor

watermark.rb

module Paperclip
  class Watermark < Processor
    # Handles watermarking of images that are uploaded.
    attr_accessor :current_geometry, :target_geometry, :format, :whiny, :convert_options, :watermark_path, :watermark_offset, :overlay, :position

    def initialize file, options = {}, attachment = nil
       super
       geometry          = options[:geometry]
       @file             = file
       @crop             = geometry[-1,1] == '#'
       @target_geometry  = Geometry.parse geometry
       @current_geometry = Geometry.from_file @file
       @convert_options  = options[:convert_options]
       @whiny            = options[:whiny].nil? ? true : options[:whiny]
       @format           = options[:format]
       @watermark_path   = options[:watermark_path]
       @position         = options[:position].nil? ? "SouthEast" : options[:position]
       @watermark_offset = options[:watermark_offset]
       @overlay          = options[:overlay].nil? ? true : false
       @current_format   = File.extname(@file.path)
       @basename         = File.basename(@file.path, @current_format)
     end

     # TODO: extend watermark

     # Returns true if the +target_geometry+ is meant to crop.
      def crop?
        @crop
      end

      # Returns true if the image is meant to make use of additional convert options.
      def convert_options?
        not @convert_options.blank?
      end

      # Performs the conversion of the +file+ into a watermark. Returns the Tempfile
      # that contains the new image.
      def make
        dst = Tempfile.new([@basename, @format].compact.join("."))
        dst.binmode

        if watermark_path
          command = "composite"
          params = %W[-gravity #{@position}]
          params += %W[-geometry '#{@watermark_offset}'] if @watermark_offset
          params += %W['#{watermark_path}' '#{fromfile}']
          params += transformation_command
          params << "'#{tofile(dst)}'"
        else
          command = "convert"
          params = ["'#{fromfile}'"]
          params += transformation_command
          params << "'#{tofile(dst)}'"
        end

        begin
          Paperclip.run(command, params.join(' '))
        rescue ArgumentError, Cocaine::CommandLineError
          raise PaperclipError, "There was an error processing the watermark for #{@basename}" if @whiny
        end

        dst
      end

      def fromfile
        File.expand_path(@file.path)
      end

      def tofile(destination)
        File.expand_path(destination.path)
      end

      def transformation_command
        scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
        trans = %W[-resize '#{scale}']
        trans += %W[-crop '#{crop}' +repage] if crop
        trans << convert_options if convert_options?
        trans
      end
  end
end