added cropper processor

app/models/user.rb

@@ -40,8 +40,9 @@ class User < ActiveRecord::Base
 
   # validates :website, format: { with: WEBSITE_REGEX }
 
-  has_attached_file :profile_picture, styles: { medium: "256x256>", thumb: "80x80>" },
+  has_attached_file :profile_picture, styles: { large: "500x500#", medium: "256x256#", small: "80x80#" },
-                    default_url: "/images/:style/no_avatar.png", use_timestamp: false
+                    default_url: "/images/:style/no_avatar.png", use_timestamp: false,
+                    processors: [:cropper]
   validates_attachment_content_type :profile_picture, :content_type => /\Aimage\/.*\Z/
   process_in_background :profile_picture
 
@@ -155,4 +156,8 @@ class User < ActiveRecord::Base
   def report_comment(report, content)
     ModerationComment.create!(user: self, report: report, content: content)
   end
+
+  def cropping?
+    !crop_x.blank? && !crop_y.blank? && !crop_w.blank? && !crop_h.blank?
+  end
 end

lib/paperclip_processors/cropper.rb

@@ -0,0 +1,22 @@
+module Paperclip
+  class Cropper < Thumbnail
+    def transformation_command
+      if crop_command
+        x = super
+        i = x.index '-crop'
+        2.times { x.delete_at i } if i
+        x
+      else
+        super
+      end
+    end
+
+    def crop_command
+      target = @attachment.instance
+      if target.cropping?
+        ['-crop', "'#{target.crop_w.to_i}x#{target.crop_h.to_i}+#{target.crop_x.to_i}+#{target.crop_y.to_i}'"]
+      end
+    end
+  end
+end
+