ruby-on-rails – 使用回形针,导轨4的水印图像

我一直在尝试按照 watermark with paperclip中列出的答案为我的图像添加水印：

Watermark.rb：

module Paperclip
  class Watermark < Processor
    # Handles watermarking of images that are uploaded.
    attr_accessor :current_geometry, :target_geometry, :format, :whiny, :convert_options, :watermark_path, :watermark_offset, :overlay, :position

    def initialize file, options = {}, attachment = nil
      super
      geometry = options[:geometry]
      @file = file
      @crop = geometry[-1,1] == '#'
      @target_geometry = Geometry.parse geometry
      @current_geometry = Geometry.from_file @file
      @convert_options = options[:convert_options]
      @whiny = options[:whiny].nil? ? true : options[:whiny]
      @format = options[:format]
      @watermark_path = options[:watermark_path]
      @position = options[:position].nil? ? "SouthEast" : options[:position]
      @watermark_offset = options[:watermark_offset]
      @overlay = options[:overlay].nil? ? true : false
      @current_format = File.extname(@file.path)
      @basename = File.basename(@file.path, @current_format)
    end

    # TODO: extend watermark

    # Returns true if the +target_geometry+ is meant to crop.
    def crop?
      @crop
    end

    # Returns true if the image is meant to make use of additional convert options.
    def convert_options?
      not @convert_options.blank?
    end

    # Performs the conversion of the +file+ into a watermark. Returns the Tempfile
    # that contains the new image.
    def make
      dst = Tempfile.new([@basename, @format].compact.join("."))
      dst.binmode

      if watermark_path
        command = "composite"
        params = %W[-gravity #{@position}]
        params += %W[-geometry '#{@watermark_offset}'] if @watermark_offset
        params += %W['#{watermark_path}' '#{fromfile}']
        params += transformation_command
        params << "'#{tofile(dst)}'"
      else
        command = "convert"
        params = ["'#{fromfile}'"]
        params += transformation_command
        params << "'#{tofile(dst)}'"
      end

      begin
        Paperclip.run(command, params.join(' '))
      rescue ArgumentError, Cocaine::CommandLineError
        raise PaperclipError, "There was an error processing the watermark for #{@basename}" if @whiny
      end

      dst
    end

    def fromfile
      File.expand_path(@file.path)
    end

    def tofile(destination)
      File.expand_path(destination.path)
    end

    def transformation_command
      scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
      trans = %W[-resize '#{scale}']
      trans += %W[-crop '#{crop}' +repage] if crop
      trans << convert_options if convert_options?
      trans
    end
  end
end

和型号代码：

has_attached_file :image, 
                  :processors => [:watermark], 
                  :styles => { 
                    :large => "640x480", 
                    :thumb => "100x100",
                    :medium => "300x300",
                        :content => {
                            :geometry => '150x153',
                            :watermark_path => Rails.root.join('app/assets/images/watermark.jpg'),
                            :position => 'SouthWest'
                        },
                  },
                  dependent: :allow_destroy

我试图更新它以使用Rails 4(将attr_accessor移动到模型中的params),但我收到错误：

uninitialized constant Paperclip::Watermark::PaperclipError

有关如何在rails 4 app中实现水印的任何提示？

更新：我能够通过以下更改Graeme的建议来解决未初始化的常量错误：

raise PaperclipError, "There was an error processing the watermark for #{@basename}" if @whiny

至：

raise Paperclip::Error.new("There was an error processing the watermark for #{@basename}") if @whiny

我还必须从模型中删除以下内容才能进行上传处理：

:url => "/images/:style/:id_:style.:extension", 
:path => ":rails_root/app/assets/images/:style/:id_:style.:extension"

我不明白目的是什么：url和：path在这种情况下,当用户上传图片时？

问题是,即使现在上传了图像,也没有显示水印.思考？

更新2：
为了正确显示水印,我不得不将模型更改为：

has_attached_file :image, 
  :processors => [:watermark], 
  :url => "/system/:class/:attachment/:id_partition/:style/:filename",
  :path => ":rails_root/public/system/:class/:attachment/:id_partition/:style/:filename",
  :styles => { 
    :large => "640x480", 
    :thumb => "100x100",
    :medium => { 
            :processors => [:watermark],
            :geometry => '300x300',
            :watermark_path => Rails.root.join('app/assets/images/icon.gif'),
            :position => 'SouthWest'
        },
  },
  dependent: :allow_destroy

关键是删除：content => .唯一剩下的问题是水印正在按比例放大以适应图像的整个宽度.有关如何停止水印缩放的任何建议？

水印被拉伸的问题是Imagemagick命令,它将两个图像组合在一起,然后调整结果的大小.

有效地运行命令将是(为了清楚起见,我缩写了实际的文件名)：

composite -gravity SouthWest icon.gif uploaded_image.gif -resize 300x300 output_image.gif

如您所见,图像已连接,然后调整大小.

我相信你需要的命令是：

convert uploaded_image.gif -resize 300x300 icon.gif -gravity SouthWest -composite output_image.gif

即调整上传图像的大小,然后添加水印.

我已经使用复合测试了这个并在命令行进行转换,它完成了我认为你正在寻找的东西.

要在代码中实现它,您需要更改make方法中的watermark_path语句：

def make

  dst = Tempfile.new([@basename, @format].compact.join("."))
  dst.binmode

  if watermark_path
    # -- original code --
    # command = "composite"
    # params = %W[-gravity #{@position}]
    # params += %W[-geometry '#{@watermark_offset}'] if @watermark_offset
    # params += %W['#{watermark_path}' '#{fromfile}']
    # params += transformation_command
    # params << "'#{tofile(dst)}'"

    # -- new code --
    command = "convert"
    params  = %W['#{fromfile}']
    params += transformation_command
    params += %W['#{watermark_path}' -gravity #{@position} -composite]
    params << "'#{tofile(dst)}'"
  else
    command = "convert"
    params = ["'#{fromfile}'"]
    params += transformation_command
    params << "'#{tofile(dst)}'"
  end

  begin
    Paperclip.run(command, params.join(' '))
  rescue ArgumentError, Cocaine::CommandLineError
    raise PaperclipError, "There was an error processing the watermark for #{@basename}" if @whiny
  end

  dst
end

免责声明：我实际上没有对此进行测试,请原谅任何错误.