code: function(config) {
              var cb = config.callback;
  
              config.callback = function(dataUrl) {
                  Kinetic.Util._getImage(dataUrl, function(img) {
                      cb(img);
                  });
              };
              this.toDataURL(config);
          }
docs: converts stage into an image.
  @method
  @memberof Kinetic.Stage.prototype
  @param {Object} config
  @param {Function} config.callback function executed when the composite has completed
  @param {String} [config.mimeType] can be "image/png" or "image/jpeg".
  "image/png" is the default
  @param {Number} [config.x] x position of canvas section
  @param {Number} [config.y] y position of canvas section
  @param {Number} [config.width] width of canvas section
  @param {Number} [config.height] height of canvas section
  @param {Number} [config.quality] jpeg quality.  If using an "image/jpeg" mimeType,
  you can specify the quality from 0 to 1, where 0 is very poor quality and 1
  is very high quality