有没有办法在 Flutter 中的 onPressed() 事件上切换相机？

Question

我正在尝试使用 Flutter 相机包使用相机服务是否有任何方法可以在按钮单击时切换到前后或后到前摄像头

Answer 1

Get available cameras and initialise the camera controller with one of them in the initState(). Also, store the available cameras to a class variable.

 CameraController _controller;
 List<CameraDescription> _availableCameras;

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

 // get available cameras
 Future<void> _getAvailableCameras() async{
   WidgetsFlutterBinding.ensureInitialized();
   _availableCameras = await availableCameras();
   _initCamera(_availableCameras.first);
 }

 // init camera
 Future<void> _initCamera(CameraDescription description) async{
  _controller = CameraController(description, ResolutionPreset.max, enableAudio: true);

  try{
    await _controller.initialize();
    // to notify the widgets that camera has been initialized and now camera preview can be done
    setState((){}); 
  }
  catch(e){
    print(e);
  }  
}

Just re-initialize the camera controller with a new camera description on button click.

void _toggleCameraLens() {
 // get current lens direction (front / rear)
 final lensDirection =  _controller.description.lensDirection;
 CameraDescription newDescription;
 if(lensDirection == CameraLensDirection.front){
    newDescription = _availableCameras.firstWhere((description) => description.lensDirection == CameraLensDirection.back);
 }
 else{
    newDescription = _availableCameras.firstWhere((description) => description.lensDirection == CameraLensDirection.front);
 }

  if(newDescription != null){
    _initCamera(newDescription);
  }
  else{
    print('Asked camera not available');
  }

}

Answer 2

I have 2 suggestions
1. Please use package camera_camera https://github.com/gabulsavul/camera_camera
It provide a good example and a lot functions already.
You can use this package directly or modify it.
screen of this package

2. In offical example code
   https://github.com/flutter/plugins/blob/master/packages/camera/example/lib/main.dart
   switch camera via this function
   You can use this example directly
   

   void onNewCameraSelected(CameraDescription cameraDescription) async { if (controller != null) { await controller.dispose(); } controller = CameraController( cameraDescription, ResolutionPreset.high, enableAudio: enableAudio, ); // If the controller is updated then update the UI. controller.addListener(() { if (mounted) setState(() {}); if (controller.value.hasError) { showInSnackBar('Camera error ${controller.value.errorDescription}'); } }); try { await controller.initialize(); } on CameraException catch (e) { _showCameraException(e); } if (mounted) { setState(() {}); } }

   Display a row of toggle to select the camera
   

    Widget _cameraTogglesRowWidget() { final List<Widget> toggles = <Widget>[]; if (cameras.isEmpty) { return const Text('No camera found'); } else { for (CameraDescription cameraDescription in cameras) { toggles.add( SizedBox( width: 90.0, child: RadioListTile<CameraDescription>( title: Icon(getCameraLensIcon(cameraDescription.lensDirection)), groupValue: controller?.description, value: cameraDescription, onChanged: controller != null && controller.value.isRecordingVideo ? null : onNewCameraSelected, ), ), ); } }

   

Answer 3

You can do something like this:

onTap: () {
      this.setState(() {
        /// Change the current selected camera State.
        this.selectedCamera =this.selectedCamera == 0 ? 1 : 0;
      });

      this._cameraController = CameraController(
          this._camerasAvailable[this.selectedCamera],
          ResolutionPreset.max,
      );
      /// Reinit camera.
      this.cameraInitialize = this._cameraController.initialize();
         
    }