flutter 踩坑记

• 如果需要做 jnifilter ，需要在 as 里设置 –target-platform=android-arm 本质上等同于 –target-platform=android-arm 新版本 flutter run 已移除此参数， 需使用：flutter build apk –target-platform android-arm

今天和同事交流，他说遇到一个问题，键盘的弹出弹回会触发 build 调用。按我理解这个应该是正常的，build 相当于 Android 的 onDraw ，随时都可能被调用。不过他给了 issue 页面我看，发现很多人遇到同样问题，并且在官方项目里 diss 官方开发的回答。不管怎样，还是发现了一个有用的东西：如何避免出现这种问题： https://stackoverflow.com/questions/52249578/how-to-deal-with-unwanted-widget-build

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缺失的必要功能！

ListView 无法跳到指定 item (只能跳到指定位移) 2017.Sep!! Provide method and/or config to programmatically scroll to ListView index

TabController 无法动态更改数据， 2018.Aug!! DefaultTabController not working with dynamic data

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有临时解决方案的

通过 URL 自外部跳转到 APP Scheme Handler 临时的解决方案：https://pub.dartlang.org/packages/uni_links

ListView 无法获取可视范围的元素 2018.July Returning index of the first visible item in ListView 解决方案：

class _VideoListState extends State<VideoList> {

  @override
  void initState() {
    super.initState();
  }

  ListView _listView;
  @override
  Widget build(BuildContext context) {
    _listView = ListView.builder(
      itemBuilder: (context,index) {
        var item = widget.list[index];
        return _getChild(item,);
      },
      itemCount: widget.list.length,
    );

    var notificationListener = NotificationListener(
      onNotification: (noti){
        if (noti is ScrollStartNotification) {
          // stop playing
        }else if(noti is ScrollEndNotification){
          // resume playing
          print("end");
          Future.microtask((){
            VideoInfo info = getMeta(0, 10);
            print("scrolling to ${info.title}");
          });
        }
      },
      child: _listView,
    );

    return notificationListener;
  }


  T getMeta<T>(double x,double y){
    var renderBox = context.findRenderObject() as RenderBox;
    var offset = renderBox.localToGlobal(Offset(x,y));

    HitTestResult result = HitTestResult();
    WidgetsBinding.instance.hitTest(result, offset);

    for(var i in result.path){
      if(i.target is RenderMetaData){
        var d = i.target as RenderMetaData;
        if(d.metaData is T) {
          return d.metaData as T;
        }
      }
    }
    return null;
  }


  Widget _getChild(VideoInfo info){
    return MetaData(
      metaData: info,
      child: VideoCard(info:info),
    );
  }
}

class VideoCard extends StatefulWidget{

  final VideoInfo info;

  const VideoCard({Key key, this.info}) : super(key: key);

  @override
  VideoCardState createState() => VideoCardState();
}

class VideoCardState extends State<VideoCard> {
  @override
  Widget build(BuildContext context) {
    return Container(child: Text("hello world ${widget.info.title}"));
  }
}


//-------------data---------------

class VideoInfo {
  final String title;
  VideoInfo(this.title);
}