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我的 rails 应用程序中安装了carrierwave。但是，当用户上传多页 pdf 时，我只希望应用程序获取文档中的第一页并将其转换为 jpeg。这可能吗，用什么命令？

这是我的上传者。

# encoding: utf-8

class ImageUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
  include CarrierWave::RMagick
  include CarrierWave::MimeTypes
  # include CarrierWave::MiniMagick

  # Include the Sprockets helpers for Rails 3.1+ asset pipeline compatibility:
  include Sprockets::Helpers::RailsHelper
  include Sprockets::Helpers::IsolatedHelper

  # Choose what kind of storage to use for this uploader:
  storage :file
  # storage :fog

  # 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
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end
  # Create different versions of your uploaded files:
  version :thumb do
    process :resize_to_fill => [150, 210]
    process :convert => :jpg

    def full_filename (for_file = model.source.file)
      super.chomp(File.extname(super)) + '.jpg'
    end
  end

  version :thumb_big do
    process :resize_to_fill => [320, 440]
    process :convert => :jpg

    def full_filename (for_file = model.source.file)
      super.chomp(File.extname(super)) + '.jpg'
    end
  end

  version :normal do
    process :resize_to_fill => [450, 630]
    process :convert => :jpg

    def full_filename (for_file = model.source.file)
      super.chomp(File.extname(super)) + '.jpg'
    end
  end

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  # 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
4

1 回答 1

10

我认为这对你有用：

阅读更多

def cover 
    manipulate! do |frame, index|
      frame if index.zero?
    end
  end   


version :thumb do
    process :cover
    process :resize_to_fill => [150, 210]
    process :convert => :jpg

    def full_filename (for_file = model.source.file)
      super.chomp(File.extname(super)) + '.jpg'
    end
  end

version :thumb_big do
   process :cover
   process :resize_to_fill => [320, 440]
   process :convert => :jpg

   def full_filename (for_file = model.source.file)
     super.chomp(File.extname(super)) + '.jpg'
   end
end

version :normal do
   process :cover
   process :resize_to_fill => [450, 630]
   process :convert => :jpg

   def full_filename (for_file = model.source.file)
     super.chomp(File.extname(super)) + '.jpg'
   end
end
于 2013-05-27T11:53:56.853 回答