flutter - 用前置摄像头录视频抖动屏幕变暗变窄

用前置摄像头录视频时屏幕变暗变窄我试了很多都没有办法解决

视频录制是全屏的，脸变得很窄很黑。我试过给出分辨率也很高但是后置摄像头工作正常

我正在使用相机插件，即:相机:^0.5.2+1

但后置摄像头工作正常

import 'dart:async';
import 'dart:io';

import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:video_player/video_player.dart';

class CameraExampleHome extends StatefulWidget {
  @override
  _CameraExampleHomeState createState() {
    return _CameraExampleHomeState();
  }
}

/// Returns a suitable camera icon for [direction].
IconData getCameraLensIcon(CameraLensDirection direction) {
  switch (direction) {
    case CameraLensDirection.back:
      return Icons.camera_rear;
    case CameraLensDirection.front:
      return Icons.camera_front;
    case CameraLensDirection.external:
      return Icons.camera;
  }
  throw ArgumentError('Unknown lens direction');
}

void logError(String code, String message) =>
    print('Error: $code\nError Message: $message');

class _CameraExampleHomeState extends State<CameraExampleHome>
    with WidgetsBindingObserver {
  CameraController controller;
  String imagePath;
  String videoPath;
  VideoPlayerController videoController;
  VoidCallback videoPlayerListener;
  bool enableAudio = true;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.inactive) {
      controller?.dispose();
    } else if (state == AppLifecycleState.resumed) {
      if (controller != null) {
        onNewCameraSelected(controller.description);
      }
    }
  }

  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: const Text('Camera example'),
      ),
      body: Column(
        children: <Widget>[
          Expanded(
            child: Container(
              child: Padding(
                padding: const EdgeInsets.all(1.0),
                child: Center(
                  child: _cameraPreviewWidget(),
                ),
              ),
              decoration: BoxDecoration(
                color: Colors.black,
                border: Border.all(
                  color: controller != null && controller.value.isRecordingVideo
                      ? Colors.redAccent
                      : Colors.grey,
                  width: 3.0,
                ),
              ),
            ),
          ),
          _captureControlRowWidget(),
          _toggleAudioWidget(),
          Padding(
            padding: const EdgeInsets.all(5.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                _cameraTogglesRowWidget(),
                _thumbnailWidget(),
              ],
            ),
          ),
        ],
      ),
    );
  }

  /// Display the preview from the camera (or a message if the preview is not available).
  Widget _cameraPreviewWidget() {
    if (controller == null || !controller.value.isInitialized) {
      return const Text(
        'Tap a camera',
        style: TextStyle(
          color: Colors.white,
          fontSize: 24.0,
          fontWeight: FontWeight.w900,
        ),
      );
    } else {
      return AspectRatio(
        aspectRatio: controller.value.aspectRatio,
        child: CameraPreview(controller),
      );
    }
  }

  /// Toggle recording audio
  Widget _toggleAudioWidget() {
    return Padding(
      padding: const EdgeInsets.only(left: 25),
      child: Row(
        children: <Widget>[
          const Text('Enable Audio:'),
          Switch(
            value: enableAudio,
            onChanged: (bool value) {
              enableAudio = value;
              if (controller != null) {
                onNewCameraSelected(controller.description);
              }
            },
          ),
        ],
      ),
    );
  }

  /// Display the thumbnail of the captured image or video.
  Widget _thumbnailWidget() {
    return Expanded(
      child: Align(
        alignment: Alignment.centerRight,
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            videoController == null && imagePath == null
                ? Container()
                : SizedBox(
                    child: (videoController == null)
                        ? Image.file(File(imagePath))
                        : Container(
                            child: Center(
                              child: AspectRatio(
                                  aspectRatio:
                                      videoController.value.size != null
                                          ? videoController.value.aspectRatio
                                          : 1.0,
                                  child: VideoPlayer(videoController)),
                            ),
                            decoration: BoxDecoration(
                                border: Border.all(color: Colors.pink)),
                          ),
                    width: 64.0,
                    height: 64.0,
                  ),
          ],
        ),
      ),
    );
  }

  /// Display the control bar with buttons to take pictures and record videos.
  Widget _captureControlRowWidget() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      mainAxisSize: MainAxisSize.max,
      children: <Widget>[
        IconButton(
          icon: const Icon(Icons.camera_alt),
          color: Colors.blue,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  !controller.value.isRecordingVideo
              ? onTakePictureButtonPressed
              : null,
        ),
        IconButton(
          icon: const Icon(Icons.videocam),
          color: Colors.blue,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  !controller.value.isRecordingVideo
              ? onVideoRecordButtonPressed
              : null,
        ),
        IconButton(
          icon: const Icon(Icons.stop),
          color: Colors.red,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  controller.value.isRecordingVideo
              ? onStopButtonPressed
              : null,
        )
      ],
    );
  }

  /// Display a row of toggle to select the camera (or a message if no camera is available).
  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,
            ),
          ),
        );
      }
    }

    return Row(children: toggles);
  }

  String timestamp() => DateTime.now().millisecondsSinceEpoch.toString();

  void showInSnackBar(String message) {
    _scaffoldKey.currentState.showSnackBar(SnackBar(content: Text(message)));
  }

  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(() {});
    }
  }

  void onTakePictureButtonPressed() {
    takePicture().then((String filePath) {
      if (mounted) {
        setState(() {
          imagePath = filePath;
          videoController?.dispose();
          videoController = null;
        });
        if (filePath != null) showInSnackBar('Picture saved to $filePath');
      }
    });
  }

  void onVideoRecordButtonPressed() {
    startVideoRecording().then((String filePath) {
      if (mounted) setState(() {});
      if (filePath != null) showInSnackBar('Saving video to $filePath');
    });
  }

  void onStopButtonPressed() {
    stopVideoRecording().then((_) {
      if (mounted) setState(() {});
      showInSnackBar('Video recorded to: $videoPath');
    });
  }

  Future<String> startVideoRecording() async {
    if (!controller.value.isInitialized) {
      showInSnackBar('Error: select a camera first.');
      return null;
    }

    final Directory extDir = await getApplicationDocumentsDirectory();
    final String dirPath = '${extDir.path}/Movies/flutter_test';
    await Directory(dirPath).create(recursive: true);
    final String filePath = '$dirPath/${timestamp()}.mp4';

    if (controller.value.isRecordingVideo) {
      // A recording is already started, do nothing.
      return null;
    }

    try {
      videoPath = filePath;
      await controller.startVideoRecording(filePath);
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }
    return filePath;
  }

  Future<void> stopVideoRecording() async {
    if (!controller.value.isRecordingVideo) {
      return null;
    }

    try {
      await controller.stopVideoRecording();
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }

    await _startVideoPlayer();
  }

  Future<void> _startVideoPlayer() async {
    final VideoPlayerController vcontroller =
        VideoPlayerController.file(File(videoPath));
    videoPlayerListener = () {
      if (videoController != null && videoController.value.size != null) {
        // Refreshing the state to update video player with the correct ratio.
        if (mounted) setState(() {});
        videoController.removeListener(videoPlayerListener);
      }
    };
    vcontroller.addListener(videoPlayerListener);
    await vcontroller.setLooping(true);
    await vcontroller.initialize();
    await videoController?.dispose();
    if (mounted) {
      setState(() {
        imagePath = null;
        videoController = vcontroller;
      });
    }
    await vcontroller.play();
  }

  Future<String> takePicture() async {
    if (!controller.value.isInitialized) {
      showInSnackBar('Error: select a camera first.');
      return null;
    }
    final Directory extDir = await getApplicationDocumentsDirectory();
    final String dirPath = '${extDir.path}/Pictures/flutter_test';
    await Directory(dirPath).create(recursive: true);
    final String filePath = '$dirPath/${timestamp()}.jpg';

    if (controller.value.isTakingPicture) {
      // A capture is already pending, do nothing.
      return null;
    }

    try {
      await controller.takePicture(filePath);
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }
    return filePath;
  }

  void _showCameraException(CameraException e) {
    logError(e.code, e.description);
    showInSnackBar('Error: ${e.code}\n${e.description}');
  }
}

class CameraApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: CameraExampleHome(),
    );
  }
}

List<CameraDescription> cameras;

Future<void> main() async {
  // Fetch the available cameras before initializing the app.
  try {
    cameras = await availableCameras();
  } on CameraException catch (e) {
    logError(e.code, e.description);
  }
  runApp(CameraApp());
}

最佳答案

我已经在 Nexus 6 模拟器中尝试了您的示例，输出如下:

看来前后摄像头都被拉长了。我找到了 this issue in GitHub你遇到了同样的问题。您可以尝试其他示例。此外，我还看到相机插件背后的团队 is working for a refactor在所述插件上。

我玩过你的代码并实现了我找到的解决方案 here .这可能是一些补救措施，但可能有更好的解决方案。

来自部分:

   Widget _cameraPreviewWidget() {
    if (controller == null || !controller.value.isInitialized) {
      return const Text(
        'Tap a camera',
        style: TextStyle(
          color: Colors.white,
          fontSize: 24.0,
          fontWeight: FontWeight.w900,
        ),
      );
    } else {
      return AspectRatio(
        aspectRatio: controller.value.aspectRatio,
        child: CameraPreview(controller),
      );
    }
  }

我已从引用的 SO post 中应用此修复程序:

Widget cameraWidget(context) {
    var camera = _cameraController.value;
    // fetch screen size
    final size = MediaQuery.of(context).size;
       
    // calculate scale depending on screen and camera ratios
    // this is actually size.aspectRatio / (1 / camera.aspectRatio)
    // because camera preview size is received as landscape
    // but we're calculating for portrait orientation
    var scale = size.aspectRatio * camera.aspectRatio;

    // to prevent scaling down, invert the value
    if (scale < 1) scale = 1 / scale;

    return Transform.scale(
      scale: scale,
      child: Center(
        child: CameraPreview(_cameraController),
      ),
  );
}

因为我使用的是当前版本的 camera 0.8.0 ，我已经考虑了高于 0.7.0 版本的给定解决方案。

这里是示例代码:

import 'dart:async';
import 'dart:io';

import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:video_player/video_player.dart';

class CameraExampleHome extends StatefulWidget {
  @override
  _CameraExampleHomeState createState() {
    return _CameraExampleHomeState();
  }
}

/// Returns a suitable camera icon for [direction].
IconData getCameraLensIcon(CameraLensDirection direction) {
  switch (direction) {
    case CameraLensDirection.back:
      return Icons.camera_rear;
    case CameraLensDirection.front:
      return Icons.camera_front;
    case CameraLensDirection.external:
      return Icons.camera;
  }
  throw ArgumentError('Unknown lens direction');
}

void logError(String code, String message) =>
    print('Error: $code\nError Message: $message');

class _CameraExampleHomeState extends State<CameraExampleHome>
    with WidgetsBindingObserver {
  CameraController controller;
  String imagePath;
  String videoPath;
  VideoPlayerController videoController;
  VoidCallback videoPlayerListener;
  bool enableAudio = true;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.inactive) {
      controller?.dispose();
    } else if (state == AppLifecycleState.resumed) {
      if (controller != null) {
        onNewCameraSelected(controller.description);
      }
    }
  }

  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: const Text('Camera example'),
      ),
      body: Column(
        children: <Widget>[
          Expanded(
            child: Container(
              child: Padding(
                padding: const EdgeInsets.all(1.0),
                child: Center(
                  child: _cameraPreviewWidget(),
                ),
              ),
              decoration: BoxDecoration(
                color: Colors.black,
                border: Border.all(
                  color: controller != null && controller.value.isRecordingVideo
                      ? Colors.redAccent
                      : Colors.grey,
                  width: 3.0,
                ),
              ),
            ),
          ),
          _captureControlRowWidget(),
          _toggleAudioWidget(),
          Padding(
            padding: const EdgeInsets.all(5.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                _cameraTogglesRowWidget(),
                _thumbnailWidget(),
              ],
            ),
          ),
        ],
      ),
    );
  }

  /// Display the preview from the camera (or a message if the preview is not available).
  Widget _cameraPreviewWidget() {
    var camera = controller.value;
    final size = MediaQuery.of(context).size;
    var scale = size.aspectRatio * camera.aspectRatio;
    if (scale < 1) scale = 1 / scale;
    if (controller == null || !controller.value.isInitialized) {
      return const Text(
        'Tap a camera',
        style: TextStyle(
          color: Colors.white,
          fontSize: 24.0,
          fontWeight: FontWeight.w900,
        ),
      );
    } else {
      return Transform.scale(
        scale: scale,
        child: Center(
          child: CameraPreview(controller),
        ),
      );
    }
  }

  /// Toggle recording audio
  Widget _toggleAudioWidget() {
    return Padding(
      padding: const EdgeInsets.only(left: 25),
      child: Row(
        children: <Widget>[
          const Text('Enable Audio:'),
          Switch(
            value: enableAudio,
            onChanged: (bool value) {
              enableAudio = value;
              if (controller != null) {
                onNewCameraSelected(controller.description);
              }
            },
          ),
        ],
      ),
    );
  }

  /// Display the thumbnail of the captured image or video.
  Widget _thumbnailWidget() {
    return Expanded(
      child: Align(
        alignment: Alignment.centerRight,
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            videoController == null && imagePath == null
                ? Container()
                : SizedBox(
                    child: (videoController == null)
                        ? Image.file(File(imagePath))
                        : Container(
                            child: Center(
                              child: AspectRatio(
                                  aspectRatio:
                                      videoController.value.size != null
                                          ? videoController.value.aspectRatio
                                          : 1.0,
                                  child: VideoPlayer(videoController)),
                            ),
                            decoration: BoxDecoration(
                                border: Border.all(color: Colors.pink)),
                          ),
                    width: 64.0,
                    height: 64.0,
                  ),
          ],
        ),
      ),
    );
  }

  /// Display the control bar with buttons to take pictures and record videos.
  Widget _captureControlRowWidget() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      mainAxisSize: MainAxisSize.max,
      children: <Widget>[
        IconButton(
          icon: const Icon(Icons.camera_alt),
          color: Colors.blue,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  !controller.value.isRecordingVideo
              ? onTakePictureButtonPressed
              : null,
        ),
        IconButton(
          icon: const Icon(Icons.videocam),
          color: Colors.blue,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  !controller.value.isRecordingVideo
              ? onVideoRecordButtonPressed
              : null,
        ),
        IconButton(
          icon: const Icon(Icons.stop),
          color: Colors.red,
          onPressed: controller != null &&
                  controller.value.isInitialized &&
                  controller.value.isRecordingVideo
              ? onStopButtonPressed
              : null,
        )
      ],
    );
  }

  /// Display a row of toggle to select the camera (or a message if no camera is available).
  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,
            ),
          ),
        );
      }
    }

    return Row(children: toggles);
  }

  String timestamp() => DateTime.now().millisecondsSinceEpoch.toString();

  void showInSnackBar(String message) {
    _scaffoldKey.currentState.showSnackBar(SnackBar(content: Text(message)));
  }

  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(() {});
    }
  }

  void onTakePictureButtonPressed() {
    takePicture().then((String filePath) {
      if (mounted) {
        setState(() {
          imagePath = filePath;
          videoController?.dispose();
          videoController = null;
        });
        if (filePath != null) showInSnackBar('Picture saved to $filePath');
      }
    });
  }

  void onVideoRecordButtonPressed() {
    startVideoRecording().then((String filePath) {
      if (mounted) setState(() {});
      if (filePath != null) showInSnackBar('Saving video to $filePath');
    });
  }

  void onStopButtonPressed() {
    stopVideoRecording().then((_) {
      if (mounted) setState(() {});
      showInSnackBar('Video recorded to: $videoPath');
    });
  }

  Future<String> startVideoRecording() async {
    if (!controller.value.isInitialized) {
      showInSnackBar('Error: select a camera first.');
      return null;
    }

    final Directory extDir = await getApplicationDocumentsDirectory();
    final String dirPath = '${extDir.path}/Movies/flutter_test';
    await Directory(dirPath).create(recursive: true);
    final String filePath = '$dirPath/${timestamp()}.mp4';

    if (controller.value.isRecordingVideo) {
      // A recording is already started, do nothing.
      return null;
    }

    try {
      videoPath = filePath;
      await controller.startVideoRecording();
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }
    return filePath;
  }

  Future<void> stopVideoRecording() async {
    if (!controller.value.isRecordingVideo) {
      return null;
    }

    try {
      await controller.stopVideoRecording();
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }

    await _startVideoPlayer();
  }

  Future<void> _startVideoPlayer() async {
    final VideoPlayerController vcontroller =
        VideoPlayerController.file(File(videoPath));
    videoPlayerListener = () {
      if (videoController != null && videoController.value.size != null) {
        // Refreshing the state to update video player with the correct ratio.
        if (mounted) setState(() {});
        videoController.removeListener(videoPlayerListener);
      }
    };
    vcontroller.addListener(videoPlayerListener);
    await vcontroller.setLooping(true);
    await vcontroller.initialize();
    await videoController?.dispose();
    if (mounted) {
      setState(() {
        imagePath = null;
        videoController = vcontroller;
      });
    }
    await vcontroller.play();
  }

  Future<String> takePicture() async {
    if (!controller.value.isInitialized) {
      showInSnackBar('Error: select a camera first.');
      return null;
    }
    final Directory extDir = await getApplicationDocumentsDirectory();
    final String dirPath = '${extDir.path}/Pictures/flutter_test';
    await Directory(dirPath).create(recursive: true);
    final String filePath = '$dirPath/${timestamp()}.jpg';

    if (controller.value.isTakingPicture) {
      // A capture is already pending, do nothing.
      return null;
    }

    try {
      await controller.takePicture();
    } on CameraException catch (e) {
      _showCameraException(e);
      return null;
    }
    return filePath;
  }

  void _showCameraException(CameraException e) {
    logError(e.code, e.description);
    showInSnackBar('Error: ${e.code}\n${e.description}');
  }
}

class CameraApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: CameraExampleHome(),
    );
  }
}

List<CameraDescription> cameras;

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // Fetch the available cameras before initializing the app.
  try {
    cameras = await availableCameras();
  } on CameraException catch (e) {
    logError(e.code, e.description);
  }
  runApp(CameraApp());
}

实际输出:

我对你的代码做了一些调整，对比前后的相机预览，似乎它可以适用于你当前的场景。考虑到相机 aspectRatio 的计算，您只需要进行一些调整。

您还可以更新您的帖子并添加一些示例输出，以便我们检查此解决方案是否适合。

除了上述解决方案外，还有更灵活的解决方案，因为许多设备的分辨率和尺寸可能会有所不同。特别是当您尝试为 Android 和 iOS 构建时。

选择您要使用的宽高比。
找到最接近该比率的分辨率。
在 Expanded 中显示预览包裹在 Column 中的小部件小部件。

但是，如果相机插件仅提供 CameraPreview 小部件，这可能会更加困难。您可以通过从 Controller.buildPreview() 方法中提取 cameraId 创建您自己的 Texture 小部件来解决这个问题。

它可能类似于下面的代码。然而，我注意到相机插件仍然有只提供 4/5 分辨率的限制。因此，最接近 desiredRatio 的分辨率最终可能会变得非常低质量。

class CameraApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyCameraHome(),
    );
  }
}

class MyCameraHome extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MyCameraHomeState();
  }
}

class MyCameraHomeState extends State<MyCameraHome> {
  static final double _desiredAspectRatio = 1.78;

  late final CameraController _controller;
  Widget _previewWidget = Container();

  @override
  void initState() {
    super.initState();
    print(_closestResolutionPreset());
    _controller = CameraController(cameras[0], _closestResolutionPreset());
    _controller.initialize().then((_) {
      if (!mounted) {
        return;
      }
      _buildPreviewWidget();
    });
  }

  ResolutionPreset _closestResolutionPreset() {
    final Map<ResolutionPreset, double> ratios = <ResolutionPreset, double>{
      ResolutionPreset.low: defaultTargetPlatform == TargetPlatform.android
          ? 320 / 240
          : 352 / 288,
      ResolutionPreset.medium: defaultTargetPlatform == TargetPlatform.android
          ? 720 / 480
          : 640 / 480,
      ResolutionPreset.high: 1280 / 720,
      ResolutionPreset.veryHigh: 1920 / 1080,
    };

    double smallestDifference = 1000;
    late ResolutionPreset resultPreset;

    for (MapEntry<ResolutionPreset, double> ratio in ratios.entries) {
      final double newDifference = (ratio.value - _desiredAspectRatio).abs();
      if (newDifference < smallestDifference) {
        resultPreset = ratio.key;
        smallestDifference = newDifference;
      }
    }

    return resultPreset;
  }

  void _buildPreviewWidget() {
    Widget previewWidget = _controller.buildPreview();
    setState(() => _previewWidget = previewWidget);
  }

  Widget _buildPictureButton() {
    return InkResponse(
      onTap: () {
        //_takePicture();
        //_recordAVideo();
      },
      child: Container(
        width: 65,
        height: 65,
        decoration: BoxDecoration(
            color: Colors.white,
            shape: BoxShape.circle,
            border: Border.all(color: Colors.grey, width: 2)),
        child: const Icon(
          Icons.camera,
          color: Colors.grey,
          size: 60,
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          Expanded(
            child: Container(
              decoration: const BoxDecoration(color: Colors.black),
              child: _previewWidget,
            ),
          ),
          Container(
            decoration: const BoxDecoration(color: Colors.black),
            padding: const EdgeInsets.only(
              bottom: 30,
              left: 10,
              right: 10,
              top: 15,
            ),
            child: Stack(
              children: <Widget>[
                Container(
                  margin: const EdgeInsets.only(top: 10),
                  alignment: Alignment.centerLeft,
                  child: IconButton(
                      icon: const Icon(
                        Icons.switch_camera,
                        color: Colors.white,
                        size: 32,
                      ),
                      onPressed: () {} //_toggleLensDirection,
                      ),
                ),
                Container(
                  alignment: Alignment.center,
                  child: _buildPictureButton(),
                )
              ],
            ),
          ),
        ],
      ),
    );
  }
}

List<CameraDescription> cameras = [];

Future<void> main() async {
  // Fetch the available cameras before initializing the app.
  try {
    WidgetsFlutterBinding.ensureInitialized();
    cameras = await availableCameras();
  } on CameraException catch (e) {
    logError(e.code, e.description);
  }
  runApp(CameraApp());
}

https://stackoverflow.com/questions/56423364/

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