code: function(value) {
                  var tmpValue = Utils.extend({}, value), keys = "rgba";
                  Utils.each(keys.split(""), function(key) {
                      if (!tmpValue.hasOwnProperty(key)) {
                          return;
                      }
                      //上溢出
                      tmpValue[key] = Math.min(Color._MAX_VALUE[key], tmpValue[key]);
                      //下溢出
                      tmpValue[key] = Math.max(Color._MIN_VALUE[key], tmpValue[key]);
                  });
                  return tmpValue;
              }
docs: 溢出控制