谷歌的VisionAPI示例FaceTracker Camera权限

Question

我正在尝试运行Google Vision FaceTracker，但我在CameraSourcePreview中的一行代码上有一个错误。

这是错误 - 呼叫需要用户可能拒绝的权限：代码应明确检查以查看是否可用(使用checkPermission(或明确处理潜在的SecurityException

这是功能 -

private void startIfReady() throws IOException {
    if (mStartRequested && mSurfaceAvailable) {
        mCameraSource.start(mSurfaceView.getHolder()); //Error
        //...other code
        mStartRequested = false;
    }
}

Answer 1

似乎您确实没有获得FaceTracker所需的正确权限。为了您的需求，只需将FaceTracker权限添加到以下实现和接口。

在我们的应用程序中，我们添加了一个带回调的接口，该界面为我们处理所有权限：

public interface PermissionAndPackageAvailabilityChecker {
    void checkCameraPermission(final PermissionResult callback);
    void checkFileIoPermission(final PermissionResult callback);
    interface PermissionResult {
        void hasPermission();
        void noPermission();
    }
}

实现非常简单：

public class DefaultPermissionAndPackage implements PermissionAndPackageAvailabilityChecker {
    private final Context mContext;
    @Inject
    public DefaultPermissionAndPackage(Context context) {
        mContext = context;
    }
    @Override
    public void checkCameraPermission(final PermissionResult callback) {
        int cameraPermission = checkPermission(mContext, Manifest.permission.CAMERA);
        if (checkHasPermission(cameraPermission)) {
            callback.hasPermission();
        } else {
            callback.noPermission();
        }
    }
    @Override
    public void checkFileIoPermission(PermissionResult callback) {
        // Check if we have write permission
        int permission = checkPermission(mContext, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        if (checkHasPermission(permission)) {
            callback.hasPermission();
        } else {
            callback.noPermission();
        }
    }
    private int getTargetSdk(int defaultVersion) {
        int targetSdkVersion = defaultVersion;
        try {
            PackageInfo packageInfo = mContext.getPackageManager().getPackageInfo(mContext.getPackageName(), 0);
            targetSdkVersion = packageInfo.applicationInfo.targetSdkVersion;
        } catch (PackageManager.NameNotFoundException ignored) {
            //Should not happen . . . I hope
        }
        return targetSdkVersion;
    }
    private int checkPermission(final Context context, final String permission) {
        int permissionResult = ActivityCompat.checkSelfPermission(context, permission);
        // this can probably be simplified but explains the logic around permissions nicely.
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP_MR1
                && getTargetSdk(Build.VERSION_CODES.LOLLIPOP_MR1) <= Build.VERSION_CODES.LOLLIPOP_MR1) {
            permissionResult = PermissionChecker.checkSelfPermission(context, permission);
            //Will check marshmallow here in the future
        }
        return permissionResult;
    }
    private boolean checkHasPermission(int permissionToCheck) {
        return permissionToCheck == PackageManager.PERMISSION_GRANTED;
    }
}