width and height methods for image processing

lib/carrierwave/processing/mini_magick.rb

@@ -235,6 +235,43 @@ def resize_and_pad(width, height, background=:transparent, gravity='Center')
       end
     end
 
+    ##
+    # Return the mini magic instance of the image
+    #
+    # === Returns
+    #
+    # #<MiniMagick::Image>
+    #
+    def mini_magic_image
+      if url
+        ::MiniMagick::Image.open(url)
+      else
+        ::MiniMagick::Image.open(current_path)
+      end
+    end
+
+    ##
+    # Gives the width of the image, useful for model validation
+    #
+    # === Returns
+    #
+    # [Integer] the image's width in pixels
+    #
+    def width
+      mini_magic_image[:width]
+    end
+
+    ##
+    # Gives the height of the image, useful for model validation
+    #
+    # === Returns
+    #
+    # [Integer] the image's height in pixels
+    #
+    def height
+      mini_magic_image[:height]
+    end
+
     ##
     # Manipulate the image with MiniMagick. This method will load up an image
     # and then pass each of its frames to the supplied block. It will then

spec/processing/mini_magick_spec.rb

@@ -12,6 +12,7 @@
     FileUtils.cp(file_path('landscape.jpg'), file_path('landscape_copy.jpg'))
     @instance.stub(:current_path).and_return(file_path('landscape_copy.jpg'))
     @instance.stub(:cached?).and_return true
+    @instance.stub(:url).and_return nil
   end
 
   after do
@@ -160,4 +161,13 @@
       end
     end
   end
+
+  describe "return_width_and_height" do
+    it "should return the width and height of the image" do
+      @instance.resize_to_fill(200, 300)
+      @instance.width.should == 200
+      @instance.height.should == 300
+    end
+  end
+
 end