refactor show_image helper (#1853)

Author: nabeta

app/helpers/picture_files_helper.rb

@@ -4,15 +4,11 @@ def show_image(picture_file, options = {size: :medium})
 
     case options[:size]
     when :medium
-      if picture_file.attachment.metadata['width'].to_i >= 600
-        return image_tag picture_file.attachment.representation(resize_to_limit: [600, nil]), alt: "*", width: 600
-      end
+      image_tag picture_file.attachment.variant(resize_to_limit: [600, nil]), alt: "*", width: 600
     when :thumb
-      if picture_file.attachment.metadata['width'].to_i >= 100
-        return image_tag picture_file.attachment.representation(resize_to_limit: [100, nil]), alt: "*", width: 100
-      end
+      image_tag picture_file.attachment.variant(resize_to_limit: [100, nil]), alt: "*", width: 100
+    else
+      image_tag picture_file.attachment, alt: "*", width: picture_file.attachment.metadata['width'], height: picture_file.attachment.metadata['height']
     end
-
-    image_tag picture_file.attachment, alt: "*", width: picture_file.attachment.metadata['width'], height: picture_file.attachment.metadata['height']
   end
 end