A hacky retina file finder/reporter. Use it for all your weird retina weirdness stuff.

retina_finder.rb

class RetinaFinder
  PATH_TO_NORMAL = "app/assets/images/"
  PATH_TO_RETINA = "app/assets/images/2x/"
  IMAGE_FORMATS  = %w(png jpg gif)
  MULTIPLIER     = 4 # 2 for regular retina, 4 for retina + 2x zoom, etc.
  
  def run
    build_file_lists
    match_files
    report_missing_or_orphaned
  end
  
  private 
  
  def build_file_lists
    @normal_files = files_for_directory(PATH_TO_NORMAL).reject { |f| f.include? PATH_TO_RETINA }
    @retina_files = files_for_directory(PATH_TO_RETINA)

    @normal_files.map! { |f| f.gsub PATH_TO_NORMAL, '' }.sort!
    @retina_files.map! { |f| f.gsub PATH_TO_RETINA, '' }.sort!
  end
  
  def files_for_directory(path)
    Dir.glob(path + "**/*.{#{IMAGE_FORMATS.join(',')}}")
  end

  def match_files
    puts "\033[1mPossible incorrect retina images:\033[22m"
    (@normal_files & @retina_files).each do |f|
      d_org, d_ret = `identify #{PATH_TO_NORMAL + f} | cut -d' ' -f3`.strip.split('x'), `identify #{PATH_TO_RETINA + f} | cut -d' ' -f3`.strip.split('x')
      d_org.map! { |n| n.to_i }
      d_ret.map! { |n| n.to_i }
      if (d_org[0] * MULTIPLIER != d_ret[0]) || (d_org[1] * MULTIPLIER != d_ret[1])
        puts "\t#{f} : Dimensions for retina incorrect.\n\t\toriginal: #{d_org.join('x')}\n\t\tretina:   #{d_ret.join('x')}"
      end
    end
  end
  
  def report_missing_or_orphaned
    left = @normal_files - @retina_files
    right = @retina_files - @normal_files
    
    if left.any?
      puts "\n\033[1mThere are/is #{left.size} file(s) that don't have retina counterpart:\033[22m"
      left.each { |f| puts "\t#{f}"}
    end

    if right.any?
      puts "\n\033[1mThere are/is #{right.size} retina file(s) that don't have normal counterpart:\033[22m"
      right.each { |f| puts "\t#{f}"}
    end
  end
end