anchor.diff:  
     @override
     Widget build(BuildContext context) {
  +    Widget des = (eventViewModel.actionDes == null || eventViewModel.actionDes.length == 0)
  +        ? new Container()
  +        : new Container(
  +            child: new Text(eventViewModel.actionDes,
  +                style: new TextStyle(fontWeight: FontWeight.bold, fontSize: 16.0, height: 1.3, color: Colors.black)),
  +            margin: new EdgeInsets.only(top: 6.0, bottom: 2.0),
  +            alignment: Alignment.topLeft);
       return new Container(
         child: new Card(
             elevation: 5.0,
  
positive.code:                       children: <Widget>[
                          new ClipOval(
                            child: new FadeInImage.assetNetwork(
                              placeholder: "static/images/logo.png",//预览图
                              fit: BoxFit.fitWidth,
                              image: eventViewModel.actionUserPic,width: 30.0, height: 30.0,
                            ),
                          ),
                          new Padding(padding: EdgeInsets.all(10.0)),
  
negative.code:                             style: new TextStyle(fontWeight: FontWeight.bold, fontSize: 16.0, height: 1.3, color: Colors.lightBlue)),
                          margin: new EdgeInsets.only(top: 6.0, bottom: 2.0),
                          alignment: Alignment.topLeft),
                      des,
                    ],
                  ),
                ))),
  