开发环境： MAC OS X 10.9.5 ruby '2.0.0' gem 'rails', '4.0.1' gem 'carrierwave', '0.10.0' gem 'mini_magick', '3.8.1'

$ convert -version
Version: ImageMagick 6.8.9-7 Q16 x86_64 2014-08-31 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2014 ImageMagick Studio LLC
Features: DPC Modules
Delegates: bzlib freetype jng jpeg ltdl lzma png xml zlib

参照 Railscasts PRO #182 cropping images revised，可以正常更新，预览截图，但提交保存之后生成的 large 和 thumb 图片，是在原图基础上生成的，不是经过截图（crop）之后生成，应该是 img.crop 不正常。google 了一天也找不到答案。

请有经验的同学帮帮忙指点一下。

class ProjectPhotoUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick
  storage :file

  def store_dir
    "uploads/project/#{model.id}"
  end

  def cache_dir
    'uploads/tmp/project-cache'
  end

  def extension_white_list
    %w(jpg jpeg gif png)
  end

  # Create different versions of your uploaded files:
  version :large do
    process resize_to_limit: [1024, -1]
  end

  version :thumb do
    process :crop
    process resize_to_fill: [200, 50]
  end

  def crop
    if model.crop_x.present?
      resize_to_limit(1024, -1)
      manipulate! do |img|
        x = model.crop_x.to_i
        y = model.crop_y.to_i
        w = model.crop_w.to_i
        h = model.crop_h.to_i
        img.crop "#{w}x#{h}+#{x}+#{y}"
      end
    end
  end

end