thumbs_with_joint.rb

class Asset

  include MongoMapper::Document
  plugin Joint

  # Next time use '#' hash mark to crop images. i.e. #200x250
  Thumbs = { :detail => "440x300>", :medium => "220x150>", :little => "100x60>", :highlights => 'crop-200x250' }

  attachment :file

  key :name, String
  key :txp_id, Integer
  timestamps!
  
  many :thumbnails,         :foreign_key => :asset_id, :dependent => :destroy
  many :primary_image_for,  :foreign_key => :primary_image_id, :class_name => "Content"

  validates_presence_of :file_size
  
  before_validation :assign_asset_name  
  after_save :make_thumbs, :if => :make_thumbs?

  def assign_asset_name
    self.name = self.file_name if self.name.blank?
  end

  def make_thumbs?
    is_image?
  end

  def is_image?
    self.file_type.scan(/image/).size > 0
  end

  # Please ignore the cropping code, need to rewrite that. 
  def make_thumbs
    original = Magick::Image.from_blob(Asset.find(self.id).file.read).first
    self.thumbnails = []
    Thumbs.each do |key, value|
      new_image = original.clone
      if value =~ /crop-/
        values = value.scan /(\d+)x(\d+)/
        new_image.crop!(Magick::CenterGravity, values.first[0].to_i, values.first[1].to_i )
      else
        new_image.change_geometry(value) {|x,y,image| image.resize!(x,y) }
      end
      path = File.join(Rails.root, 'tmp', "#{key}-#{self.file_name}" )
      ff = File.open( path , 'w+')
      ff.write(new_image.to_blob)
      self.thumbnails << Thumbnail.new(:format => key.to_s, :file => ff )
      FileUtils.rm path
    end
  end

end