Add crop_resize Dragonfly processor

The build in thumb processor does not support to resize the image after
it has been cropped.

In order to make it work in dragonfly 1.4 we add our own processor.

alchemy_cms.gemspec

@@ -37,7 +37,7 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency "awesome_nested_set", ["~> 3.1"]
   gem.add_runtime_dependency "cancancan", [">= 2.1", "< 4.0"]
   gem.add_runtime_dependency "coffee-rails", [">= 4.0", "< 6.0"]
-  gem.add_runtime_dependency "dragonfly", ["~> 1.0", ">= 1.0.7"]
+  gem.add_runtime_dependency "dragonfly", ["~> 1.4"]
   gem.add_runtime_dependency "dragonfly_svg", ["~> 0.0.4"]
   gem.add_runtime_dependency "gutentag", ["~> 2.2", ">= 2.2.1"]
   gem.add_runtime_dependency "handlebars_assets", ["~> 0.23"]

app/models/alchemy/picture/transformations.rb

@@ -206,12 +206,12 @@ def center_crop(dimensions, upsample)
     # Use imagemagick to custom crop an image. Uses -thumbnail for better performance when resizing.
     #
     def xy_crop_resize(dimensions, top_left, crop_dimensions, upsample)
-      crop_argument = "-crop #{dimensions_to_string(crop_dimensions)}"
+      crop_argument = dimensions_to_string(crop_dimensions)
       crop_argument += "+#{top_left[:x]}+#{top_left[:y]}"
 
-      resize_argument = "-resize #{dimensions_to_string(dimensions)}"
+      resize_argument = dimensions_to_string(dimensions)
       resize_argument += ">" unless upsample
-      image_file.convert "#{crop_argument} #{resize_argument}"
+      image_file.crop_resize(crop_argument, resize_argument)
     end
 
     # Used when centercropping.

config/initializers/dragonfly.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 require "dragonfly_svg"
+require "alchemy/dragonfly/processors/crop_resize"
 
 # Logger
 Dragonfly.logger = Rails.logger
@@ -12,3 +13,7 @@
 
 # Dragonfly 1.4.0 only allows `quality` as argument to `encode`
 Dragonfly::ImageMagick::Processors::Encode::WHITELISTED_ARGS << "flatten"
+
+Rails.application.config.after_initialize do
+  Dragonfly.app(:alchemy_pictures).add_processor(:crop_resize, Alchemy::Dragonfly::Processors::CropResize.new)
+end

lib/alchemy/dragonfly/processors/crop_resize.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "dragonfly/image_magick/commands"
+
+module Alchemy
+  module Dragonfly
+    module Processors
+      class CropResize
+        include ::Dragonfly::ParamValidators
+
+        IS_CROP_ARGUMENT = ->(args_string) {
+          args_string.match?(::Dragonfly::ImageMagick::Processors::Thumb::CROP_GEOMETRY)
+        }
+
+        IS_RESIZE_ARGUMENT = ->(args_string) {
+          args_string.match?(::Dragonfly::ImageMagick::Processors::Thumb::RESIZE_GEOMETRY)
+        }
+
+        def call(content, crop_argument, resize_argument)
+          validate!(crop_argument, &IS_CROP_ARGUMENT)
+          validate!(resize_argument, &IS_RESIZE_ARGUMENT)
+          ::Dragonfly::ImageMagick::Commands.convert(
+            content,
+            "-crop #{crop_argument} -resize #{resize_argument}"
+          )
+        end
+
+        def update_url(attrs, _args = "", opts = {})
+          format = opts["format"]
+          attrs.ext = format if format
+        end
+      end
+    end
+  end
+end

spec/libraries/dragonfly/processors/crop_resize_spec.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+require_relative "../../../support/dragonfly_test_app"
+
+RSpec.describe Alchemy::Dragonfly::Processors::CropResize do
+  let(:app) { dragonfly_test_app }
+  let(:file) { Pathname.new(File.expand_path("../../../fixtures/80x60.png", __dir__)) }
+  let(:image) { Dragonfly::Content.new(app, file) }
+  let(:processor) { described_class.new }
+
+  it "validates bad crop and resize arguments" do
+    expect {
+      processor.call(image, "h4ck", "m3")
+    }.to raise_error(Dragonfly::ParamValidators::InvalidParameter)
+  end
+
+  it "works with correct crop and resize arguments" do
+    expect {
+      processor.call(image, "4x4+0+0", "20x20>")
+    }.to_not raise_error
+  end
+end

spec/models/alchemy/picture_variant_spec.rb

@@ -70,7 +70,7 @@
         end
 
         it "crops and resizes the picture" do
-          expect(subject.steps[0].arguments).to eq(["-crop 123x44+0+0 -resize 160x120>"])
+          expect(subject.steps[0].arguments).to eq(["123x44+0+0", "160x120>"])
         end
       end
     end

spec/support/dragonfly_test_app.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+def dragonfly_test_app(name = nil)
+  app = Dragonfly::App.instance(name)
+  app.datastore = Dragonfly::MemoryDataStore.new
+  app.secret = "test secret"
+  app
+end