android - 如何正确打开camera2 api上的闪光灯？

Question

我使用标准的谷歌示例canera2api

在这里我试着坚持下去CONTROL_AE_MODE_ON_ALWAYS_FLASH

我是怎么做的，我改变了这条线

private void captureStillPicture() {
    try {
        final Activity activity = getActivity();
        if (null == activity || null == mCameraDevice) {
            return;
        }
        // This is the CaptureRequest.Builder that we use to take a picture.
        final CaptureRequest.Builder captureBuilder =
                mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
        captureBuilder.addTarget(mImageReader.getSurface());

        // Use the same AE and AF modes as the preview.
        captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);



---->>>>    ---- //            setAutoFlash(captureBuilder);

 ---->>>>   ++++    captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_ALWAYS_FLASH);




        // Orientation
        int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
        captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, getOrientation(rotation));

        CameraCaptureSession.CaptureCallback CaptureCallback
                = new CameraCaptureSession.CaptureCallback() {

            @Override
            public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                           @NonNull CaptureRequest request,
                                           @NonNull TotalCaptureResult result) {
                showToast("Saved: " + mFile);
                Log.d(TAG, mFile.toString());
                unlockFocus();
            }
        };

        mCaptureSession.stopRepeating();
        mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

那么这里

private void unlockFocus() {
    try {
        // Reset the auto-focus trigger
        mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
                CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);


---->>>> ----  //            setAutoFlash(mPreviewRequestBuilder);
---->>>> ++++        mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_ALWAYS_FLASH);



        mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
                mBackgroundHandler);
        // After this, the camera will go back to the normal state of preview.
        mState = STATE_PREVIEW;
        mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback,
                mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

和这里

mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
                new CameraCaptureSession.StateCallback() {

                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
                        // The camera is already closed
                        if (null == mCameraDevice) {
                            return;
                        }

                        // When the session is ready, we start displaying the preview.
                        mCaptureSession = cameraCaptureSession;
                        try {
                            // Auto focus should be continuous for camera preview.
                            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                                    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
                            // Flash is automatically enabled when necessary.


---->>>> ----  //                                setAutoFlash(mPreviewRequestBuilder);
                             ---->>>> ++++  mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_ALWAYS_FLASH);



                            // Finally, we start displaying the camera preview.
                            mPreviewRequest = mPreviewRequestBuilder.build();
                            mCaptureSession.setRepeatingRequest(mPreviewRequest,
                                    mCaptureCallback, mBackgroundHandler);
                        } catch (CameraAccessException e) {
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onConfigureFailed(
                            @NonNull CameraCaptureSession cameraCaptureSession) {
                        showToast("Failed");
                    }
                }, null
        );

如果我使用这种配置启动应用程序，它每次都可以完美运行并且每次都闪现，但是如果我启动这个应用程序，Samsung S6我会在闪现后立即预览堆栈。

奇怪的是为什么有些设备工作得很好，而另一个得到问题......

但是我已经尝试修复它，以便我想出下一步，如果我在captureStillPicture()方法中只更改一个参数，就在这里

private void captureStillPicture() {
    try {
        final Activity activity = getActivity();
        if (null == activity || null == mCameraDevice) {
            return;
        }
        // This is the CaptureRequest.Builder that we use to take a picture.
        final CaptureRequest.Builder captureBuilder =
                mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
        captureBuilder.addTarget(mImageReader.getSurface());

        // Use the same AE and AF modes as the preview.
        captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);



---->>>> ---- //            setAutoFlash(captureBuilder);
---->>>> ---- //            captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_ALWAYS_FLASH);
---->>>> ++++        captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_AUTO_FLASH);

        // Orientation
        int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
        captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, getOrientation(rotation));

        CameraCaptureSession.CaptureCallback CaptureCallback
                = new CameraCaptureSession.CaptureCallback() {

            @Override
            public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                           @NonNull CaptureRequest request,
                                           @NonNull TotalCaptureResult result) {
                showToast("Saved: " + mFile);
                Log.d(TAG, mFile.toString());
                unlockFocus();
            }
        };

        mCaptureSession.stopRepeating();
        mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

我已更改CONTROL_AE_MODE_ON_ALWAYS_FLASH为CONTROL_AE_MODE_ON_AUTO_FLASH，现在此配置可以Samsung S6完美运行，但它停止与其他设备一起使用...

最后我有两种不同的配置，如果我应用一个，一些设备支持它并且工作完美，但另一种设备不......反之亦然......

我究竟做错了什么？