gistfile1.rb

require 'image_science'

class Thumb

  class << self

    # if a :thumb_dir is provided then the thumb
    # will be saved in the sub directory provided
    # with the same name as the original otherwise
    # it will be saved with "_th" after the name

    def resize(path, size, options = {})
      options[:thumb_dir] ||= ""

      ImageScience.with_image path do |img|
        img.cropped_thumbnail(size) do |thumb|
          name = name_thumb(path, options[:thumb_dir])
          File.delete(name) if File.exist?(name)
          thumb.save(name)
        end
      end
    end

    def resize_all(dir_path, size, options = {})
      options[:thumb_dir] ||= ""

      Dir.foreach(dir_path) do |file|
        img_types = /\.(jpg|jpeg|png|gif)$/
        next unless file.match(img_types)
        next if file.match(/_th#{img_types}/ )
        dir_path += "/" unless dir_path[-1] == "/"
        resize((dir_path + file), size, options)
      end
    end

    private
    
    def name_thumb(path, thumb_dir)
      parts = path.split("/")

      if thumb_dir.empty?
        extension = /\.\w+$/
        name = parts.pop.gsub(extension, "") + "_th" + path.match(extension)[0]
      else
        name = parts.pop
        dir = parts.join("/") + "/" + thumb_dir
        Dir.mkdir(dir) if !Dir.exist?(dir)
        name = thumb_dir + "/" + name
      end
      parts.push("/").push(name).join("/")
    end
  end

end