fully externalize exporter; untested

Gemfile

@@ -37,6 +37,8 @@ group :dependencies do
   gem "autoprefixer-rails"
   gem "uglifier"
 
+  # switch to main version once ready:
+  gem "mapknitter-exporter", git: 'https://github.com/publiclab/mapknitter-exporter', glob: '*.gemspec'
 end
 
 group :test do

Gemfile.lock

@@ -1,3 +1,10 @@
+GIT
+  remote: https://github.com/publiclab/mapknitter-exporter
+  revision: e46886898d0c5b36863ce5a066b85c4c4a5cd0da
+  glob: *.gemspec
+  specs:
+    mapknitter-exporter (0.0.1)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -195,6 +202,7 @@ DEPENDENCIES
   geokit-rails (= 1.1.4)
   image_science (= 1.2.6)
   jshintrb
+  mapknitter-exporter!
   mysql2 (< 0.4)
   oa-openid (= 0.3.2)
   open_id_authentication
@@ -220,4 +228,4 @@ RUBY VERSION
    ruby 2.4.6p354
 
 BUNDLED WITH
-   1.17.1
+   1.17.3

app/models/map.rb

@@ -210,13 +210,12 @@ def run_export(user, resolution)
         :map_id => id
       })
     end
-    Exporter.run_export(user,
+    MapKnitterExporter.run_export(
+      user.id,
       resolution,
       self.export,
-      self.id,
       self.slug,
       Rails.root.to_s,
-      self.average_scale,
       self.placed_warpables,
       key)
   end

app/models/warpable.rb

@@ -1,3 +1,5 @@
+require "mapknitterExporter"
+
 class Warpable < ActiveRecord::Base
 
   attr_accessible :image
@@ -141,9 +143,8 @@ def url=(uri)
     self.uploaded_data = io
   end
 
-  # TODO: simplify/reduce # of parameters needed here:
   def generate_perspectival_distort(pxperm, path)
-    Exporter.generate_perspectival_distort(pxperm, path, nodes_array, id, image_file_name, image, height, width)
+    MapKnitterExporter.generate_perspectival_distort(pxperm, path, nodes_array, image_file_name, image.url(:original), height, width, Rails.root)
   end
 
   def user_id