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This is another question in pursuit of an answer to this question.

In my watermark processor if I set the watermark image's path to a static watermark image, everything works just fine.

I have three models: Watermark, Gallery, and Photo. Watermark has_many :galleries. Gallery belongs_to :watermark and has_many :photos. Photo belongs_to :gallery and mount_uploader :image, PhotoUploader.

Here's what I'd like to do in photo_uploader.rb:

  version :large do
    process :watermark
    process :resize_to_limit => [600, 600]
  end

  def watermark
    manipulate! do |img|
      watermark = Magick::Image.read(model.gallery.watermark.image_url).first
      img = img.composite(watermark, Magick::CenterGravity, Magick::OverCompositeOp)
    end
  end

While using model methods/attributes works fine in the store_dir method, it doesn't work in the watermark processor. How can I pass the model.gallery.watermark.image_url argument to the watermark processor?

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1 回答 1

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问题是，当图像安装在模型上时，watemark def 中的变量，在上传器类中，不可用。就是这样做的。我正在使用 mongoid 来处理 mongoDB。我在模型中设置了一个参数，它将保存我想要的值，例如。the_current_model.gallery.watermark.image_url 的值。此参数将是 user_image。

class Asset
  include Mongoid::Document
  mount_uploader :image, AssetUploader

  field :user_image

  attr_accessible :user_image

  after_save :mark_it

  private
  def mark_it
    image.recreate_versions! if user_image.present?
  end

end

解决这个问题的关键是在将数据保存在数据库中之后重新创建图像（正如您在调用 mark_it def 的模型上看到的那样），并且允许将参数 user_image 用于您的上传器类。

class AssetUploader < CarrierWave::Uploader::Base

  include CarrierWave::RMagick

  storage :file
  # storage :fog

  after :cache, :unlink_original_cache

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  process :resize_to_fit => [800, 800]
  process :quality => 80

  version :thumb do
    process :resize_to_fit => [200, 200]
  end

  version :large do
    process :watermark
  end

  def watermark
    if model.user_name.present?
      manipulate! do |img|
        text = Magick::Draw.new 
        text.gravity = Magick::CenterGravity
        text.fill = 'white'    
        text.pointsize = 40 
        text.stroke = 'none' 
        text.annotate(img, 0, 0, 0, 0, "#{model.user_name}") 
        img
      end
    end
  end

  def unlink_original(file)
    File.delete path if version_name.blank?
  end

  def unlink_original_cache(file)
    File.delete if version_name.blank?
  end

  def extension_white_list
    %w(jpg jpeg gif png)
  end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end

现在关键在这里：

def watermark
        if model.user_name.present?
          manipulate! do |img|
            text = Magick::Draw.new 
            text.gravity = Magick::CenterGravity
            text.fill = 'white'    
            text.pointsize = 40 
            text.stroke = 'none' 
            text.annotate(img, 0, 0, 0, 0, "#{model.user_name}") 
            img
          end
        end
      end

如果设置了模型上的 user_name 参数（在数据库上创建），则方法 watermark 仅创建带有水印的图像。因此，当数据保存在数据库上时，此参数可供您的上传程序类根据需要使用。

我就是这么做的，而且效果很好！我希望它可以帮助！

于 2012-03-13T13:24:14.300 回答