Gab Social. All are welcome.

lib/paperclip/lazy_thumbnail.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module Paperclip
+  class LazyThumbnail < Paperclip::Thumbnail
+    def make
+      return File.open(@file.path) unless needs_convert?
+
+      if options[:geometry]
+        min_side = [@current_geometry.width, @current_geometry.height].min.to_i
+        options[:geometry] = "#{min_side}x#{min_side}#" if @target_geometry.square? && min_side < @target_geometry.width
+      elsif options[:pixels]
+        width  = Math.sqrt(options[:pixels] * (@current_geometry.width.to_f / @current_geometry.height.to_f)).round.to_i
+        height = Math.sqrt(options[:pixels] * (@current_geometry.height.to_f / @current_geometry.width.to_f)).round.to_i
+        options[:geometry] = "#{width}x#{height}>"
+      end
+
+      Paperclip::Thumbnail.make(file, options, attachment)
+    end
+
+    private
+
+    def needs_convert?
+      needs_different_geometry? || needs_different_format? || needs_metadata_stripping?
+    end
+
+    def needs_different_geometry?
+      (options[:geometry] && @current_geometry.width != @target_geometry.width && @current_geometry.height != @target_geometry.height) ||
+        (options[:pixels] && @current_geometry.width * @current_geometry.height > options[:pixels])
+    end
+
+    def needs_different_format?
+      @format.present? && @current_format != @format
+    end
+
+    def needs_metadata_stripping?
+      @attachment.instance.respond_to?(:local?) && @attachment.instance.local?
+    end
+  end
+end