ruby on rails - paperclip imagemagick convert to grayscale and crop to fit 144x144# -

client.rb

  has_attached_file :avatar,   :path => ":rails_root/public/system/:attachment/:id/:style/:filename",   :url => "/system/:attachment/:id/:style/:filename",   :styles => {:thumb => "144x144#", :grayscale => { :processors => [:grayscale] }} 

the thumb version version works great, image cropped required size, grayscale converts image grayscale, image not being cropped, here grayscale generator found on stackoverflow:

lib/grayscale.rb

module paperclip   # handles grayscale conversion of images uploaded.   class grayscale < processor      def initialize file, options = {}, attachment = nil       super       @format = file.extname(@file.path)       @basename = file.basename(@file.path, @format)     end       def make        src = @file        dst = tempfile.new([@basename, @format])        dst.binmode         begin          parameters = []          parameters << ":source"          parameters << "-colorspace gray"          parameters << ":dest"           parameters = parameters.flatten.compact.join(" ").strip.squeeze(" ")           success = paperclip.run("convert", parameters, :source => "#{file.expand_path(src.path)}[0]", :dest => file.expand_path(dst.path))        rescue paperclipcommandlineerror => e          raise papercliperror, "there error during grayscale conversion #{@basename}" if @whiny        end         dst      end   end end 

to convert image grayscale params being sent imagemagick in array, question - params have send imagemagick "144x144#" in paperclip.

i tried follow logs see "144x144#" looks in logs, looking this: -crop '144x144+30+0', tried use in generator , send params like:

 parameters = []  parameters << ":source"  parameters << "-crop '144x144+30+0'"  parameters << "-colorspace gray"  parameters << ":dest" 

and looked worked if used same image uploaded before, if upload 1 image cropped wrong. came conclusion param: -crop '144x144+30+0' generated paperclip specific image size, , different size different params sent fit 144px.

how crop image in generator fit equivalent of 144x144# paperclip or params need send imagemagick achieve this. thank you.

i decided go other way, i'll use cropped file has desired size , use imagemagick convert 1 grayscale , save right folder after model saved. grayscale processor can removed used system command work imagemagick.

p.s. there might downsides of answer, couldn't find any.

client.rb

  has_attached_file :avatar,   :path => ":rails_root/public/system/:attachment/:id/:style/:filename",   :url => "/system/:attachment/:id/:style/:filename",   :styles => {:thumb => "144x144#", :grayscale => "144x144#"}    after_save :convert_grayscale    def convert_grayscale     system "convert public/system/avatars/#{self.id}/thumb/#{self.avatar.original_filename} -fx '(r+g+b)/3' public/system/avatars/#{self.id}/grayscale/#{self.avatar.original_filename}"   end 

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