问相机预览以4:3的纵横比水平拉伸

EN

class CameraScreenGithub extends StatefulWidget {
  const CameraScreenGithub({Key? key}) : super(key: key);

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

class _CameraScreenGithubState extends State<CameraScreenGithub> {
  CameraController? _cameraController;
  Future<void>? _initializeControllerFuture;
  List<CameraDescription> _cameraDescription = [];

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

  Future<void> _initializeCamera() async {
    _cameraDescription.addAll(await availableCameras());
    _setCamera(_cameraDescription[0]);
  }

  _setCamera(CameraDescription description) {
    _cameraController = CameraController(description, ResolutionPreset.high);
    _initializeControllerFuture = _cameraController?.initialize();
    if (mounted) setState(() {});
  }

  @override
  void dispose() {
    _cameraController?.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: Stack(
                children: [
                  Center(
                    child: _cameraPreview(),
                  ),
                  Positioned(
                    top: 20,
                    left: 20,
                    right: 20,
                    child: _aspectRatioButton(),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _cameraPreview() => ClipRRect(
        borderRadius: BorderRadius.circular(16),
        child: FutureBuilder<void>(
          future: _initializeControllerFuture,
          builder: (context, snapshot) {
            if (snapshot.connectionState == ConnectionState.done) {
              return CameraPreview(_cameraController!);
            }
            return Container();
          },
        ),
      );

  Widget _aspectRatioButton() => IconButton(
        icon: Icon(
          Icons.aspect_ratio,
          color: Colors.white,
        ),
        onPressed: () {
          _cameraController?.value =
              _cameraController!.value.copyWith(previewSize: Size(320, 240));
          setState(() {});
        },
      );
}