Question

我是一名新开发人员，刚刚开始使用flutter。我正在尝试制作相机应用，并且遵循了本教程：

https://www.youtube.com/watch?v=_nS00ZKnINQ

我收到一个错误：Instance member 'takePicture' can't be accessed using static access.

您可以在此代码块中查看整个文件。请不要犹豫，询问您是否需要整个项目目录。

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';

class CameraScreen extends StatefulWidget {
  @override
  _CameraScreenState createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> {
  CameraController cameraController;
  List cameras;
  int selectedCameraIndex;
  String imgPath;

  Future _initCameraController(CameraDescription cameraDescription) async {
    if (cameraController != null) {
      await cameraController.dispose();
    }

    cameraController =
        CameraController(cameraDescription, ResolutionPreset.high);
    cameraController.addListener(() {
      if (mounted) {
        setState(() {});
      }
    });

    if (cameraController.value.hasError) {
      print('!!!Camera error!!! ${cameraController.value.errorDescription}');
    }

    try {
      await cameraController.initialize();
    } on CameraException catch (e) {
      _showCameraException(e);
    }

    if (mounted) {
      setState(() {});
    }
  }

  /// Display Camera Preview

  Widget _cameraPreviewWidget() {
    if (cameraController == null || cameraController.value.isInitialized) {
      return const Text(
        'Loading...',
        style: TextStyle(
          color: Colors.white,
          fontSize: 20.0,
          fontWeight: FontWeight.w900,
        ),
      );
    }

    return AspectRatio(
      aspectRatio: cameraController.value.aspectRatio,
      child: CameraPreview(cameraController),
    );
  }

  /// Display control bar with buttons to take picture

  Widget _cameraControlWidget(context) {
    return Expanded(
        child: Align(
      alignment: Alignment.center,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
          FloatingActionButton(
              child: Icon(
                Icons.camera,
                color: Colors.black,
              ),
              backgroundColor: Colors.white,
              onPressed: () {
                _onCapturePressed(context);
              })
        ],
      ),
    ));
  }

  /// Display a row of toggles to select the camera
  Widget _cameraToggleRowWidget() {
    if (cameras == null || cameras.isEmpty) {
      return Spacer();
    }

    CameraDescription selectedCamera = cameras[selectedCameraIndex];
    CameraLensDirection lensDirection = selectedCamera.lensDirection;

    return Expanded(
        child: Align(
      alignment: Alignment.centerLeft,
      child: FlatButton.icon(
          onPressed: _onSwitchCamera,
          icon: Icon(
            _getCameraLensIcon(lensDirection),
            color: Colors.white,
            size: 24,
          ),
          label: Text(
            '${lensDirection.toString().substring(lensDirection.toString().indexOf('.') + 1).toUpperCase()}',
            style: TextStyle(
              color: Colors.white,
              fontWeight: FontWeight.w500,
            ),
          )),
    ));
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return null;
  }

  void _onSwitchCamera() {
    selectedCameraIndex =
        selectedCameraIndex < cameras.length - 1 ? selectedCameraIndex + 1 : 0;

    CameraDescription selectedCamera = cameras[selectedCameraIndex];

    _initCameraController(selectedCamera);
  }

  IconData _getCameraLensIcon(CameraLensDirection lensDirection) {
    switch (lensDirection) {
      case CameraLensDirection.back:
        return CupertinoIcons.switch_camera;
      case CameraLensDirection.front:
        return CupertinoIcons.switch_camera_solid;
      case CameraLensDirection.external:
        return CupertinoIcons.photo_camera;
      default:
        return Icons.device_unknown;
    }
  }
}

void _onCapturePressed(context) async {
  try {
    final path =
        join((await getTemporaryDirectory()).path, '${DateTime.now()}.png)');

    await CameraController.takePicture(path);
  } catch (e) {
    _showCameraException(e);
  }
}

void _showCameraException(CameraException e) {
  String errorText = 'Error: ${e.code} \n Error Message: ${e.description}';
  print(errorText);
}

我正在Windows 10上的Flutter中使用VS Code

Answer 1

不要将 <TextInput placeholder={"A Variable"} onChangeText={(text) => this.setState({a: text}) } value={this.state.a} /> 作为静态方法调用。您必须使用初始化的控制器：

takePicture

要访问它，请将您的方法 cameraController.takePicture(path); 移动到您的类主体中。可以在 here 中找到您教程中的工作代码。

Flutter错误：无法使用静态访问权限访问实例成员“ takePicture”

1 个答案: