Add :read option to manipulate!

lib/carrierwave/processing/rmagick.rb

@@ -277,7 +277,9 @@ def resize_and_pad(width, height, background=:transparent, gravity=::Magick::Cen
     #
     def manipulate!(options={}, &block)
       cache_stored_file! if !cached?
-      image = ::Magick::Image.read(current_path)
+
+      read_block = create_info_block(options[:read])
+      image = ::Magick::Image.read(current_path, &read_block)
 
       frames = if image.size > 1
         list = ::Magick::ImageList.new
@@ -296,7 +298,7 @@ def manipulate!(options={}, &block)
         frame
       end
 
-      write_block = create_write_block(options[:write])
+      write_block = create_info_block(options[:write])
       if options[:format]
         frames.write("#{options[:format]}:#{current_path}", &write_block)
       else
@@ -309,9 +311,9 @@ def manipulate!(options={}, &block)
 
   private
 
-    def create_write_block(write_options)
-      return nil unless write_options
-      assignments = write_options.map { |k, v| "self.#{k} = #{v}" }
+    def create_info_block(options)
+      return nil unless options
+      assignments = options.map { |k, v| "self.#{k} = #{v}" }
       code = "lambda { |img| " + assignments.join(";") + "}"
       eval code
     end

spec/processing/rmagick_spec.rb

@@ -80,13 +80,20 @@
       ::Magick::Image::Info.any_instance.should_receive(:quality=).with(50)
       ::Magick::Image::Info.any_instance.should_receive(:depth=).with(8)
 
-      @instance.manipulate! do |img, index, options|
-        options[:write] = {
+      @instance.manipulate! :write => {
           :quality => 50,
           :depth => 8
         }
-        img
-      end
+    end
+
+    it 'should support passing read options to RMagick' do
+      ::Magick::Image::Info.any_instance.should_receive(:density=).with(10)
+      ::Magick::Image::Info.any_instance.should_receive(:size=).with("200x200")
+
+      @instance.manipulate! :read => {
+          :density => 10,
+          :size => %{"200x200"}
+        }
     end
   end