Extract common image processing into a module

lib/jekyll/responsive_image.rb

@@ -7,6 +7,7 @@ require 'rmagick'
 require 'jekyll/responsive_image/version'
 require 'jekyll/responsive_image/defaults'
 require 'jekyll/responsive_image/utils'
+require 'jekyll/responsive_image/image_processor'
 require 'jekyll/responsive_image/resize_handler'
 require 'jekyll/responsive_image/tag'
 require 'jekyll/responsive_image/block'

lib/jekyll/responsive_image/block.rb

@@ -1,8 +1,6 @@
 module Jekyll
   class ResponsiveImage
     class Block < Liquid::Block
-      include ResponsiveImage::Utils
-
       def render(context)
         config = ResponsiveImage.defaults.dup
         config.merge!(context.registers[:site].config['responsive_image'])
@@ -10,10 +8,9 @@ module Jekyll
         attributes = YAML.load(super)
         image_template = attributes['template'] || config['template']
 
-        resize_handler = ResizeHandler.new
-        img = Magick::Image::read(attributes['path']).first
-        attributes['original'] = image_hash(attributes['path'], img.columns, img.rows)
-        attributes['resized'] = resize_handler.resize_image(img, config)
+        image = ImageProcessor.process(attributes['path'], config)
+        attributes['original'] = image[:original]
+        attributes['resized'] = image[:resized]
 
         partial = File.read(image_template)
         template = Liquid::Template.parse(partial)

lib/jekyll/responsive_image/image_processor.rb

@@ -0,0 +1,23 @@
+module Jekyll
+  class ResponsiveImage
+    class ImageProcessor
+      include ResponsiveImage::Utils
+
+      def process(image_path, config)
+        raise SyntaxError.new('Invalid image path specified') unless File.exists?(image_path)
+
+        resize_handler = ResizeHandler.new
+        img = Magick::Image::read(image_path).first
+
+        {
+          original: image_hash(image_path, img.columns, img.rows),
+          resized: resize_handler.resize_image(img, config),
+        }
+      end
+
+      def self.process(image_path, config)
+        self.new.process(image_path, config)
+      end
+    end
+  end
+end

lib/jekyll/responsive_image/tag.rb

@@ -1,8 +1,6 @@
 module Jekyll
   class ResponsiveImage
     class Tag < Liquid::Tag
-      include ResponsiveImage::Utils
-
       def initialize(tag_name, markup, tokens)
         super
 
@@ -18,10 +16,9 @@ module Jekyll
         config = ResponsiveImage.defaults.dup
         config.merge!(context.registers[:site].config['responsive_image'])
 
-        resize_handler = ResizeHandler.new
-        img = Magick::Image::read(@attributes['path']).first
-        @attributes['original'] = image_hash(@attributes['path'], img.columns, img.rows)
-        @attributes['resized'] = resize_handler.resize_image(img, config)
+        image = ImageProcessor.process(@attributes['path'], config)
+        @attributes['original'] = image[:original]
+        @attributes['resized'] = image[:resized]
 
         image_template = @attributes['template'] || config['template']