From 697f4a93ad386f9fb7795f0ba68f815f16ebad0f Mon Sep 17 00:00:00 2001
From: George Claghorn <george.claghorn@gmail.com>
Date: Fri, 10 Aug 2018 12:10:13 -0400
Subject: Extract transformers

---
 activestorage/app/models/active_storage/variant.rb | 10 +--
 .../app/models/active_storage/variation.rb         | 79 +++++-----------------
 2 files changed, 19 insertions(+), 70 deletions(-)

(limited to 'activestorage/app/models/active_storage')

diff --git a/activestorage/app/models/active_storage/variant.rb b/activestorage/app/models/active_storage/variant.rb
index 239df34d81..ea57fa5f78 100644
--- a/activestorage/app/models/active_storage/variant.rb
+++ b/activestorage/app/models/active_storage/variant.rb
@@ -101,14 +101,8 @@ class ActiveStorage::Variant
       end
     end
 
-    def transform(image)
-      result = variation.transform(image, format: format)
-
-      begin
-        yield result
-      ensure
-        result.close!
-      end
+    def transform(image, &block)
+      variation.transform(image, format: format, &block)
     end
 
     def upload(file)
diff --git a/activestorage/app/models/active_storage/variation.rb b/activestorage/app/models/active_storage/variation.rb
index ae1376a6cf..3adc2407e5 100644
--- a/activestorage/app/models/active_storage/variation.rb
+++ b/activestorage/app/models/active_storage/variation.rb
@@ -47,13 +47,9 @@ class ActiveStorage::Variation
   # saves the transformed image into a temporary file. If +format+ is specified
   # it will be the format of the result image, otherwise the result image
   # retains the source format.
-  def transform(file, format: nil)
+  def transform(file, format: nil, &block)
     ActiveSupport::Notifications.instrument("transform.active_storage") do
-      if processor
-        image_processing_transform(file, format)
-      else
-        mini_magick_transform(file, format)
-      end
+      transformer.transform(file, format: format, &block)
     end
   end
 
@@ -63,63 +59,22 @@ class ActiveStorage::Variation
   end
 
   private
-    # Applies image transformations using the ImageProcessing gem.
-    def image_processing_transform(file, format)
-      operations = transformations.each_with_object([]) do |(name, argument), list|
-        if name.to_s == "combine_options"
-          ActiveSupport::Deprecation.warn("The ImageProcessing ActiveStorage variant backend doesn't need :combine_options, as it already generates a single MiniMagick command. In Rails 6.1 :combine_options will not be supported anymore.")
-          list.concat argument.keep_if { |key, value| value.present? }.to_a
-        elsif argument.present?
-          list << [name, argument]
+    def transformer
+      if ActiveStorage.variant_processor
+        begin
+          require "image_processing"
+        rescue LoadError
+          ActiveSupport::Deprecation.warn <<~WARNING
+            Generating image variants will require the image_processing gem in Rails 6.1.
+            Please add `gem 'image_processing', '~> 1.2'` to your Gemfile.
+          WARNING
+
+          ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
+        else
+          ActiveStorage::Transformers::ImageProcessingTransformer.new(transformations)
         end
-      end
-
-      processor
-        .source(file)
-        .loader(page: 0)
-        .convert(format)
-        .apply(operations)
-        .call
-    end
-
-    # Applies image transformations using the MiniMagick gem.
-    def mini_magick_transform(file, format)
-      image = MiniMagick::Image.new(file.path, file)
-
-      transformations.each do |name, argument_or_subtransformations|
-        image.mogrify do |command|
-          if name.to_s == "combine_options"
-            argument_or_subtransformations.each do |subtransformation_name, subtransformation_argument|
-              pass_transform_argument(command, subtransformation_name, subtransformation_argument)
-            end
-          else
-            pass_transform_argument(command, name, argument_or_subtransformations)
-          end
-        end
-      end
-
-      image.format(format) if format
-
-      image.tempfile.tap(&:open)
-    end
-
-    # Returns the ImageProcessing processor class specified by `ActiveStorage.variant_processor`.
-    def processor
-      begin
-        require "image_processing"
-      rescue LoadError
-        ActiveSupport::Deprecation.warn("Using mini_magick gem directly is deprecated and will be removed in Rails 6.1. Please add `gem 'image_processing', '~> 1.2'` to your Gemfile.")
-        return nil
-      end
-
-      ImageProcessing.const_get(ActiveStorage.variant_processor.to_s.camelize) if ActiveStorage.variant_processor
-    end
-
-    def pass_transform_argument(command, method, argument)
-      if argument == true
-        command.public_send(method)
-      elsif argument.present?
-        command.public_send(method, argument)
+      else
+        ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
       end
     end
 end
-- 
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