我一直在尝试给我的图片添加水印,按照使用paperclip添加水印中列出的答案进行操作:
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
以及模型代码:
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
我尝试将这个更新以与Rails 4 兼容(将attr_accessor移动到模型中的params),但是我收到了以下错误:
uninitialized constant Paperclip::Watermark::PaperclipError
有什么技巧可以在Rails 4应用中实现水印?
更新:我能够通过Graeme下面的建议解决未初始化常量错误:
raise PaperclipError, "There was an error processing the watermark for #{@basename}" if @whiny
to:
raise Paperclip::Error.new("There was an error processing the watermark for #{@basename}") if @whiny
为了使上传过程顺利进行,我还需要从模型中删除以下内容:
:url => "/images/:style/:id_:style.:extension",
:path => ":rails_root/app/assets/images/:style/:id_:style.:extension"
在用户上传图片时,我不理解:url和:path的用途是什么?
问题是,即使现在图像已经被上传,水印也没有显示出来。你有什么想法吗?
更新2: 为了正确显示水印,我不得不更改模型:
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
重要的一点是移除: content =>。唯一剩下的问题是水印会放大以适应整个图像的宽度。有没有建议如何停止水印缩放?