如何在 Camera2 API 中启用前置摄像头？

Question

如何在 Camera2 上启用前置摄像头API.Can有人帮忙吗？我有这个 Camera2 API 代码。这只设置设备的主摄像头，我想在按钮上启用前后摄像头 click.What 是 LENS_FACING_FRONT，我是 android编程。

 private void setUpCameraOutputs(int width, int height) {
    Activity activity = getActivity();
    CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
    try {
        for (String cameraId : manager.getCameraIdList()) {
            CameraCharacteristics characteristics
                    = manager.getCameraCharacteristics(cameraId);

            // We don't use a front facing camera in this sample.
            Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
            if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
                continue;
            }

            StreamConfigurationMap map = characteristics.get(
                    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
            if (map == null) {
                continue;
            }

            // For still image captures, we use the largest available size.
            Size largest = Collections.max(
                    Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
                    new CompareSizesByArea());
            mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
                    ImageFormat.JPEG, /*maxImages*/2);
            mImageReader.setOnImageAvailableListener(
                    mOnImageAvailableListener, mBackgroundHandler);

            // Danger, W.R.! Attempting to use too large a preview size could  exceed the camera
            // bus' bandwidth limitation, resulting in gorgeous previews but the storage of
            // garbage capture data.
            mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
                    width, height, largest);

            // We fit the aspect ratio of TextureView to the size of preview we picked.
            int orientation = getResources().getConfiguration().orientation;
            if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                mTextureView.setAspectRatio(
                        mPreviewSize.getWidth(), mPreviewSize.getHeight());
            } else {
                mTextureView.setAspectRatio(
                        mPreviewSize.getHeight(), mPreviewSize.getWidth());
            }

            mCameraId = cameraId;
            return;
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    } catch (NullPointerException e) {
        // Currently an NPE is thrown when the Camera2API is used but not supported on the
        // device this code runs.
        ErrorDialog.newInstance(getString(R.string.camera_error))
                .show(getChildFragmentManager(), FRAGMENT_DIALOG);
    }
}

Answer 1

我们可以使用CameraManager来迭代系统中所有可用的摄像头，每个摄像头都有一个指定的cameraId。使用 cameraId，我们可以获取指定相机设备的属性。这些属性由 class CameraCharacteristics 表示。 "is it front or back camera"、"output resolutions supported"等可以在那里查询。

您可以获得官方示例应用程序here

This example found in Google Git repo will demo for you checking the permission before launching camera in new Marshmallow using Camera2 API

查看此 article 了解更多信息。

如何在 Camera2 API 中启用前置摄像头？

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