anchor.diff:  }
   
   class _RTCVideoViewState extends State<RTCVideoView> {
  -  double _aspectRatio;
  -
  -  @override
  -  void initState() {
  -    super.initState();
  -    _setCallbacks();
  -    _aspectRatio = widget._renderer.aspectRatio;
  -  }
  -
  -  @override
  -  void dispose() {
  -    super.dispose();
  -    widget._renderer.onStateChanged = null;
  -  }
  -
  -  void _setCallbacks() {
  -    widget._renderer.onStateChanged = () {
  -      setState(() {
  -        _aspectRatio = widget._renderer.aspectRatio;
  -      });
  -    };
  -  }
  -
     Widget _buildVideoView(BoxConstraints constraints) {
       return Container(
           width: constraints.maxWidth,
  
positive.code:     final Map<dynamic, dynamic> map = event;
      switch (map['event']) {
        case 'didTextureChangeRotation':
          _rotation = map['rotation'];
          break;
        case 'didTextureChangeVideoSize':
          _width = 0.0 + map['width'];
          _height = 0.0 + map['height'];
          break;
        case 'didFirstFrameRendered':
          break;
      }
      if (this.onStateChanged != null) {
        this.onStateChanged();
      }
    }
  
  
negative.code:         child: FittedBox(
              fit: widget.objectFit == RTCVideoViewObjectFit.RTCVideoViewObjectFitContain ? BoxFit.contain : BoxFit.cover,
              child: Center(
                child: ValueListenableBuilder<RTCVideoValue>(
                    valueListenable: widget._renderer,
                    builder: (BuildContext context, RTCVideoValue value, Widget child) {
                      return SizedBox(
                        width: constraints.maxHeight * value.aspectRatio,
                        height: constraints.maxHeight,
                        child: child,
                      );
                    },
                    child: Transform(
                        transform: Matrix4.identity()
                          ..rotateY(widget.mirror ? -pi : 0.0),
                        alignment: FractionalOffset.center,
                        child: Texture(textureId: widget._renderer._textureId))),
              )));
    }
  
    @override
  