anchor.diff:  }
   
   class RTCVideoView extends StatefulWidget {
  -  final RTCVideoRenderer renderer;
  +  RTCVideoRenderer renderer;
     RTCVideoView(this.renderer);
     @override
     _RTCVideoViewState createState() => new _RTCVideoViewState(renderer);
   }
   
   class _RTCVideoViewState extends State<RTCVideoView> {
  -  final RTCVideoRenderer renderer;
  -  var aspectRatio = 1.0;
  +  RTCVideoRenderer renderer;
  +  double _aspectRatio;
   
     _RTCVideoViewState(this.renderer);
   
  
positive.code:   int _rotation = 0;
    double _width = 0.0, _height = 0.0;
    bool _mirror;
    MediaStream _srcObject;
    RTCVideoViewObjectFit _objectFit =
        RTCVideoViewObjectFit.RTCVideoViewObjectFitContain;
    StreamSubscription<dynamic> _eventSubscription;
    VideoSizeChangeCallback onVideoSizeChanged;
    VideoRotationChangeCallback onVideoRotationChanged;
    dynamic onFirstFrameRendered;
  
    initialize() async {
      final Map<dynamic, dynamic> response =
  
negative.code:     switch (map['event']) {
        case 'didTextureChangeRotation':
          _rotation = map['rotation'];
          _updateAspectRatio();
          break;
        case 'didTextureChangeVideoSize':
          _width = 0.0 + map['width'];
          _height = 0.0 + map['height'];
          _updateAspectRatio();
          break;
        case 'didFirstFrameRendered':
          _updateAspectRatio();
          break;
      }
    }
  
    void _updateAspectRatio() {
      double aspectRatio = _aspectRatio;
      double textureWidth = 0.0,
          textureHeight = 0.0;
      if (_rotation == 90 || _rotation == 270) {
        textureWidth = min(_width, _height);
        textureHeight = max(_width, _height);
        if (_height != 0.0) {
          aspectRatio = _width / _height;
        }
      } else {
        textureWidth = max(_width, _height);
        textureHeight = min(_width, _height);
        if (_height != 0.0) {
          aspectRatio = _width / _height;
        }
      }
      if(this.onAspectRatioChanged != null && _aspectRatio != aspectRatio){
        this.onAspectRatioChanged(aspectRatio);
      }
      _aspectRatio = aspectRatio;
    }
  
    void errorListener(Object obj) {
  