watermark with paperclip - ruby-on-rails

Question

according to this example (http://dimaspriyanto.com/2010/06/08/image-watermarking-with-paperclip/), I try to put a watermark on every picture I upload (for now, I restrain myself to the large one).
And guess what? It doesn't work!
So in my picture model, I have
require 'paperclip_processors/watermark'
has_attached_file :image,
:styles => {:medium => "300x300^", :thumb => "150x105^",
:large => {
:geometry => "460",
:watermark_path => ":rails_root/public/images/watermark.png"
}
},
:url => "/images/:style/:id_:style.:extension",
:path => ":rails_root/public/images/:style/:id_:style.:extension"
and in /lib/paperclip_processors/watermark.rb, I have:
module Paperclip
class Watermark < Processor
attr_accessor :current_geometry, :target_geometry, :format, :whiny, :convert_options, :watermark_path, :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]
#overlay = options[:overlay].nil? ? true : false
#current_format = File.extname(#file.path)
#basename = File.basename(#file.path, #current_format)
end
def crop?
#crop
end
def convert_options?
not #convert_options.blank?
end
def make
dst = Tempfile.new([#basename, #format].compact.join("."))
dst.binmode
if watermark_path
command = "composite"
params = "-gravity #{#position} #{watermark_path} #{fromfile} #{transformation_command} #{tofile(dst)}"
else
command = "convert"
params = "#{fromfile} #{transformation_command} #{tofile(dst)}"
end
begin
success = Paperclip.run(command, params)
rescue PaperclipCommandLineError
raise PaperclipError, "There was an error processing the watermark for #{#basename}" if #whiny
end
dst
end
def fromfile
"\"#{ File.expand_path(#file.path) }[0]\""
end
def tofile(destination)
"\"#{ File.expand_path(destination.path) }[0]\""
end
def transformation_command
scale, crop = #current_geometry.transformation_to(#target_geometry, crop?)
trans = "-resize \"#{scale}\""
trans << " -crop \"#{crop}\" +repage" if crop
trans << " #{convert_options}" if convert_options?
trans
end
end
end
The watermark is in /public/images/ and it doesn't crash in the process, I mean the pictures are uploaded, in every size but the large one is nude, without the watermark.
Any idea?

Answer 1

Here's the preprocessor that works (I use it)
https://gist.github.com/2499137
Here's sample code for you model:
has_attached_file :data,
:processors => [:watermark],
:url => "/ckeditor_assets/pictures/:id/:style_:basename.:extension",
:path => ":rails_root/public/ckeditor_assets/pictures/:id/:style_:basename.:extension",
:styles => {
:thumb => '118x100#',
:content => {
:geometry => '700>',
:watermark_path => "#{Rails.root}/public/images/watermark.png",
:position => 'SouthWest'
},
}