flutter相机预览

这解决了问题，但是也可能有更好的解决方案。（感谢@ user1462442从上面的评论。）

@overrideWidget build(BuildContext context) { if (!_isReady) return new Container(); if (!controller.value.initialized) return new Container(); return new Scaffold(   body: new Container(     child: new AspectRatio(       aspectRatio: controller.value.aspectRatio,       child: new CameraPreview(controller),     ),   ),   floatingActionButton: new FloatingActionButton(     onPressed: _isReady ? capture : null,     child: const Icon(       Icons.camera,       color: Colors.white,     ),   ),   floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat, );}