Added support for the "crop" method to the vips processor.

lib/carrierwave/processing/vips.rb

@@ -78,6 +78,14 @@ def resize_to_fill(width, height, gravity='centre')
       def resize_and_pad(width, height, background=nil, gravity='centre', alpha=nil)
         process :resize_and_pad => [width, height, background, gravity, alpha]
       end
+
+      def resize_to_fit(width, height)
+        process :resize_to_fit => [width, height]
+      end
+
+      def crop(left, top, width, height)
+        process :crop => [left, top, width, height]
+      end
     end
 
     ##
@@ -208,6 +216,31 @@ def resize_and_pad(width, height, background=nil, gravity='centre', alpha=nil, c
       end
     end
 
+    ##
+    # Crop the image to the contents of a box positioned at [left] and [top], with the dimensions given
+    # by [width] and [height]. 
+    # 
+    #
+    # === Parameters
+    #
+    # [left (integer)] left edge of area to extract
+    # [top (integer)] top edge of area to extract
+    # [width (Integer)] width of area to extract
+    # [height (Integer)] height of area to extract
+    #
+    # === Yields
+    #
+    # [Vips::Image] additional manipulations to perform
+    #
+    def crop(left, top, width, height, combine_options: {})
+      width, height = resolve_dimensions(width, height)
+
+      vips! do |builder|
+        builder.crop(left, top, width, height)
+          .apply(combine_options)
+      end
+    end
+
     ##
     # Returns the width of the image in pixels.
     #

spec/processing/vips_spec.rb

@@ -188,6 +188,15 @@
     end
   end
 
+  describe '#crop' do
+    it 'extracts an area defined from the left and top positions, with the given width and height' do
+      instance.crop(70, 40, 500, 400)
+
+      expect(instance).to have_dimensions(500, 400)
+      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/jpeg/)
+    end
+  end
+
   describe "#width and #height" do
     it "returns the width and height of the image" do
       instance.resize_to_fill(200, 300)