BikeBikeBike/app/uploaders/poster_uploader.rb

# encoding: utf-8
require 'carrierwave/processing/mini_magick'

class PosterUploader < CarrierWave::Uploader::Base

  include CarrierWave::ImageOptimizer
  include CarrierWave::MiniMagick

  storage :file
  process :optimize

  @@sizes = {
    :thumb   => [120,  120],
    :icon    => [48,   48],
    :preview => [512,  512],
    :full    => [1024, 1024]
  }

  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  version :thumb do
    process :resize_to_fill => @@sizes[:thumb]
  end

  version :icon do
    process :resize_to_fill => @@sizes[:icon]
  end

  version :preview do
    process :resize_to_fit => @@sizes[:preview]
  end

  version :full do
    process :resize_to_fit => @@sizes[:full]
  end

  def image
    @image ||= MiniMagick::Image.open(file.path)
  end

  def is_landscape?
    image['width'] > image['height']
  end

  def manipulate!
    cache_stored_file! if !cached?
    image = ::MiniMagick::Image.open(current_path)

    begin
      image.format(@format.to_s.downcase) if @format
      image = yield(image)
      image.write(current_path)
      begin
        image.run_command("identify", current_path)
      rescue
        image.run_command("identify", '"' + current_path + '"')
      end
    ensure
      image.destroy!
    end
  rescue ::MiniMagick::Error, ::MiniMagick::Invalid => e
    default = I18n.translate(:"errors.messages.mini_magick_processing_error", :e => e, :locale => :en)
    message = I18n.translate(:"errors.messages.mini_magick_processing_error", :e => e, :default => default)
    raise CarrierWave::ProcessingError, message
  end

end