Move lib/danbooru, lib/danbooru_image_resizer to app/logical.

app/logical/danbooru_image_resizer.rb

@@ -0,0 +1,51 @@
+module DanbooruImageResizer
+  def resize(read_path, write_path, width, height, resize_quality = 90)
+    image = Magick::Image.read(read_path).first
+    geometry = "#{width}x>"
+
+    if width == Danbooru.config.small_image_width
+      # wider than it is tall
+      geometry = "#{Danbooru.config.small_image_width}x#{Danbooru.config.small_image_width}>"
+    end
+
+    image.change_geometry(geometry) do |new_width, new_height, img|
+      img.resize!(new_width, new_height)
+      width = new_width
+      height = new_height
+    end
+
+    image = flatten(image, width, height)
+    image.strip!
+
+    image.write(write_path) do
+      self.quality = resize_quality
+      # setting PlaneInterlace enables progressive encoding for JPEGs
+      self.interlace = Magick::PlaneInterlace
+    end
+
+    image.destroy!
+    FileUtils.chmod(0664, write_path)
+  end
+
+  def flatten(image, width, height)
+    if image.alpha?
+      # since jpeg can't represent transparency, we need to create an image list,
+      # put a white image on the bottom, then flatten it.
+
+      list = Magick::ImageList.new
+      list.new_image(width, height) do
+        self.background_color = "#FFFFFF"
+      end
+      list << image
+      flattened_image = list.flatten_images
+      list.each do |image|
+        image.destroy!
+      end
+      return flattened_image
+    else
+      return image
+    end
+  end
+
+  module_function :resize, :flatten
+end