振荡的方面的错误

Question

你好，我试图做一个地理围栏响应，我有一堆谷歌地图网址和一个圆圈。这段代码没问题：

                                new Card(
                                  elevation: 2.0,
                                  child: new Stack(
                                    alignment: AlignmentDirectional.center,
                                    children: <Widget>[

                                      new Container(
                                        child: new Image.network(staticMapUri.toString()),
                                      ),
                                      new Container(
                                        alignment: new FractionalOffset(0.0, 0.0),
                                        decoration: new BoxDecoration(
                                          shape: BoxShape.circle,
                                          color: Colors.lightBlue.withOpacity(0.5),
                                        ),
                                        child:
                                        new AspectRatio(
                                          aspectRatio: MediaQuery.of(context).size.longestSide/GPS2,
                                          child :
                                          FractionalTranslation(
                                            translation: Offset(0.0, 0.0),
                                            child: new Container(
                                            ),
                                          ),
                                        ),
                                      ),
                                      new Container(
                                        //padding: const EdgeInsets.only(bottom:10.0),
                                        margin: new EdgeInsets.all(140.0),
                                        child : Icon(Icons.location_on, color: Colors.white, size: 25.0),
                                      ),
                                    ],
                                  ),
                                ),

但是我搜索用滑块值替换GPS2是动态的，所以这里是代码：

---

                                       new Slider(
                                        value: valperimetre,
                                        onChanged: (double e) => change(e),
                                        activeColor: Colors.lightBlue,
                                        inactiveColor :Colors.grey,
                                        divisions: 10,
                                        label: "$valperimetre""m",
                                        max : 500.0,
                                        min: 0.0,
                                      ),

---

              new Card(
                elevation: 2.0,
                child: new Stack(
                  alignment: AlignmentDirectional.center,
                  children: <Widget>[

                    new Container(
                      child: new Image.network(staticMapUri.toString()),
                    ),
                    new Container(
                      alignment: new FractionalOffset(0.0, 0.0),
                      decoration: new BoxDecoration(
                        shape: BoxShape.circle,
                        color: Colors.lightBlue.withOpacity(0.5),
                      ),
                      child:
                      new AspectRatio(
                        aspectRatio: MediaQuery.of(context).size.longestSide/valperimetre,
                        child :
                        FractionalTranslation(
                          translation: Offset(0.0, 0.0),
                          child: new Container(
                          ),
                        ),
                      ),
                    ),
                    new Container(
                      //padding: const EdgeInsets.only(bottom:10.0),
                      margin: new EdgeInsets.all(140.0),
                      child : Icon(Icons.location_on, color: Colors.white, size: 25.0),
                    ),
                  ],
                ),
              ),

但目前我有这样的错误：“如果我正常重建app：断言失败：第399行pos 15：'aspectRatio.isFinite'：不是真的。”如果我在重建应用程序之后将valperimetre替换为100.0，并且在我用valperimetre替换100.0之后，我可以将其重新加载。

Answer 1

尝试将此条件检查到代码中。

//your code here
 child:(valperimetre == 0.0 || valperimetre == null) ? 
        Container()
       :new AspectRatio(
          aspectRatio: MediaQuery.of(context).size.longestSide/valperimetre,
//your code here