add invert filter

scripts/modules/filter.invert.js

@@ -0,0 +1,11 @@
+Filter.prototype.filter_invert = function(pixels = this.pixels(),p = null)
+{
+  var d = pixels.data;
+  for (var i=0; i<d.length; i+=4) {
+      for (var j=0; j<3; j++) {
+          d[i+j] = 255 - d[i+j];
+      }
+  }
+	ronin.canvas.clear();
+	ronin.canvas.context().putImageData(pixels, 0, 0, 0, 0, pixels.width, pixels.height);
+}

scripts/modules/filter.js

@@ -19,6 +19,9 @@ function Filter(element)
       case "chromatic":
         this.filter_chromatic(this.pixels(),p);
         break;
+      case "invert":
+        this.filter_invert(this.pixels(),p);
+        break;
     }
   }