makeShapeComposite function for Kineticjs

myns.makeShapeComposite.js

/**
* makeShapeComposite function on a gloabl namespace - see var namespace
*
* ns.kineticSupport.makeShapeComposite(shape, operation);
* @param Kinetic.Shape (family)
* @param Sting - valid globalCompositeOperation name
* @return the supplied shape after globalCompositeOperation set
*/
(function(){
    var namespace = 'myns',
        ns = window[namespace] = (window[namespace] || {});
    
    ns.kineticSupport || (ns.kineticSupport={});
    
    ns.kineticSupport.makeShapeComposite = function(shape, operation) {
        shape.attrs._drawFunc = shape.attrs.drawFunc;
        shape.attrs.drawFunc = function (kineticShape) {
            kineticShape.context.save();
            kineticShape.context.globalCompositeOperation = operation;
            this.attrs._drawFunc.call(this, kineticShape);
            kineticShape.context.restore();
        };
        return shape;
    };
}());