matenia/edge_captcha

begin
  require 'RMagick' 
rescue Exception => e
  puts "Warning: RMagick not installed, you cannot generate captcha images on this machine"
end

require 'edge_captcha/util'

module EdgeCaptcha
  module ImageGenerator
    @@eligible_chars     = (2..9).to_a + %w(A B C D E F G H J K L M N P Q R S T U V X Y Z)
    @@default_parameters = {
      :image_width    => 240,
      :image_height   => 50,
      :captcha_length => 5,
      :file_format => 'png'
    }

    def self.generate_captcha_image(params = {})

      params.reverse_merge!(@@default_parameters)

      file_format = ['png', 'gif'].include?(params[:file_format]) ? ".#{params[:file_format]}" : '.png'

      text_img  = Magick::Image.new(params[:image_width].to_i, params[:image_height].to_i)
      black_img = Magick::Image.new(params[:image_width].to_i, params[:image_height].to_i) do 
        self.background_color = 'black'
      end

      # Generate a 5 character random string
      random_string = (1..params[:captcha_length].to_i).collect { @@eligible_chars[rand(@@eligible_chars.size)] }.join(' ')

      # Gerenate the filename based on the string where we have removed the spaces
      filename = EdgeCaptcha::Util::encrypt_string(random_string.gsub(' ', '').downcase) + file_format

      # Render the text in the image
      text_img.annotate(Magick::Draw.new, 0,0,0,0, random_string) {
        self.gravity = Magick::WestGravity
        self.font_family = 'Thonburi'
        self.font_weight = Magick::BoldWeight
        self.fill = '#666666'
        self.stroke = 'black'
        self.stroke_width = 2
        self.pointsize = 44
      }

      # Apply a little blur and fuzzing
      text_img = text_img.gaussian_blur(1.2, 1.2)
      text_img = text_img.sketch(20, 30.0, 30.0)
      text_img = text_img.wave(3, 90)

      # Now we need to get the white out
      text_mask = text_img.negate
      text_mask.matte = false

      # Add cut-out our captcha from the black image with varying tranparency
      black_img.composite!(text_mask, Magick::CenterGravity, Magick::CopyOpacityCompositeOp)

      # Write the file to disk
      puts 'Writing image file ' + filename
      black_img.write(filename) # { self.depth = 8 }

      # Collect rmagick
      GC.start
    end
  end
end